text:
@article{Anderegg2016,
abstract = {Drought- and heat-driven tree mortality, along with associated insect outbreaks, have been observed globally in recent decades and are expected to increase in future climates. Despite its potential to profoundly alter ecosystem carbon and water cycles, how tree mortality scales up to ecosystem functions and fluxes is uncertain. We describe a framework for this scaling where the effects of mortality are a function of the mortality attributes, such as spatial clustering and functional role of the trees killed, and ecosystem properties, such as productivity and diversity. We draw upon remote-sensing data and ecosystem flux data to illustrate this framework and place climate-driven tree mortality in the context of other major disturbances. We find that emerging evidence suggests that climate-driven tree mortality impacts may be relatively small and recovery times are remarkably fast ({\~{}}4 years for net ecosystem production). We review the key processes in ecosystem models necessary to simulate the effects of mortality on ecosystem fluxes and highlight key research gaps in modeling. Overall, our results highlight the key axes of variation needed for better monitoring and modeling of the impacts of tree mortality and provide a foundation for including climate-driven tree mortality in a disturbance framework.},
author = {Anderegg, William R.L. and Martinez-Vilalta, Jordi and Cailleret, Maxime and Camarero, Jesus Julio and Ewers, Brent E. and Galbraith, David and Gessler, Arthur and Grote, R{\"{u}}diger and ying Huang, Cho and Levick, Shaun R. and Powell, Thomas L. and Rowland, Lucy and S{\'{a}}nchez-Salguero, Ra{\'{u}}l and Trotsiuk, Volodymyr},
doi = {10.1007/s10021-016-9982-1},
issn = {14350629},
journal = {Ecosystems},
keywords = {biodiversity,carbon and water fluxes,disturbance,productivity,recovery,resilience},
number = {6},
pages = {1133--1147},
title = {{When a Tree Dies in the Forest: Scaling Climate-Driven Tree Mortality to Ecosystem Water and Carbon Fluxes}},
volume = {19},
year = {2016}
}
@article{Asner2009,
abstract = {African savannas are undergoing management intensification, and decision makers are increasingly challenged to balance the needs of large herbivore populations with the maintenance of vegetation and ecosystem diversity. Ensuring the sustainability of Africa's natural protected areas requires information on the efficacy of management decisions at large spatial scales, but often neither experimental treatments nor large-scale responses are available for analysis. Using a new airborne remote sensing system, we mapped the three-dimensional (3-D) structure of vegetation at a spatial resolution of 56 cm throughout 1640 ha of savanna after 6-, 22-, 35-, and 41-year exclusions of herbivores, as well as in unprotected areas, across Kruger National Park in South Africa. Areas in which herbivores were excluded over the short term (6 years) contained 38{\%}-80{\%} less bare ground compared with those that were exposed to mammalian herbivory. In the longer-term ({\textgreater} 22 years), the 3-D structure of woody vegetation differed significantly between protected and accessible landscapes, with up to 11-fold greater woody canopy cover in the areas without herbivores. Our maps revealed 2 scales of ecosystem response to herbivore consumption, one broadly mediated by geologic substrate and the other mediated by hillslope-scale variation in soil nutrient availability and moisture conditions. Our results are the first to quantitatively illustrate the extent to which herbivores can affect the 3-D structural diversity of vegetation across large savanna landscapes.},
author = {Asner, G. P. and Levick, S. R. and Kennedy-Bowdoin, T. and Knapp, D. E. and Emerson, R. and Jacobson, J. and Colgan, M. S. and Martin, R. E.},
doi = {10.1073/pnas.0810637106},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
keywords = {Ecological sustainability,Ecosystem heterogeneity,Kruger national park,Park management,Protected areas,South africa,Vegetation structure},
number = {12},
pages = {4947--4952},
title = {{Large-scale impacts of herbivores on the structural diversity of African savannas}},
volume = {106},
year = {2009}
}
@article{Asner2015,
abstract = {Sable antelope, Hippotragus niger, populations have declined substantially in Kruger National Park, South Africa despite large-area protection from land use and poaching. Since Africa's large mammal populations are restricted to protected areas, understanding how to manage parks for biological diversity is critically important to the sustainability of faunal populations into the future. To better understand the drivers of sable decline, we analyzed landscapes where herds persist in the Pretoriuskop region of Kruger - identified by GPS collar telemetry data from eight individuals in five herds remaining in this area, and compared them to landscapes where sable herds have recently disappeared. We mapped these landscapes with satellite-based spectral data on vegetation greenness and fire frequency and Carnegie Airborne Observatory LiDAR (Light Detection and Ranging) data on 3-D vegetation structure. Within their home ranges, sable herds consistently selected areas with high fire frequency, high tree cover and low shrub cover. However, there were no consistent differences in habitat features between the home ranges of current sable herds and areas formerly supporting herds. Locally deteriorating habitat conditions were therefore not responsible for the decline in sables in this region of the park. Our study also illustrates how multi-sensor, 3-D mapping of ecosystems provides a means to assess causes and consequences of changing animal habitats over time.},
author = {Asner, G. P. and Owen-Smith, N. and Loarie, S. R. and Davies, A. B. and {Le Roux}, E. and Levick, S. R.},
doi = {10.1111/jzo.12269},
issn = {14697998},
journal = {Journal of Zoology},
keywords = {Animal movement,Carnegie Airborne Observatory,Habitat use,Kruger National Park,LiDAR,Savanna ecology,Vegetation structure},
number = {3},
pages = {225--234},
title = {{Habitat differences do not explain population declines of sable antelope in an African savanna}},
volume = {297},
year = {2015}
}
@article{Asner2012,
abstract = {Herbivores cause treefalls in African savannas, but rates are unknown at large scales required to forecast changes in biodiversity and ecosystem processes. We combined landscape-scale herbivore exclosures with repeat airborne Light Detection and Ranging of 58 429 trees in Kruger National Park, South Africa, to assess sources of savanna treefall across nested gradients of climate, topography, and soil fertility. Elephants were revealed as the primary agent of treefall across widely varying savanna conditions, and a large-scale 'elephant trap' predominantly removes maturing savanna trees in the 5-9 m height range. Treefall rates averaged 6 times higher in areas accessible to elephants, but proportionally more treefall occurred on high-nutrient basalts and in lowland catena areas. These patterns were superimposed on a climate-mediated regime of increasing treefall with precipitation in the absence of herbivores. These landscape-scale patterns reveal environmental controls underpinning herbivore-mediated tree turnover, highlighting the need for context-dependent science and management.},
author = {Asner, Gregory P. and Levick, Shaun R.},
doi = {10.1111/j.1461-0248.2012.01842.x},
issn = {1461023X},
journal = {Ecology Letters},
keywords = {Carnegie Airborne Observatory,Elephant trap,Herbivory,Kruger National Park,LiDAR,Mega-herbivore,South Africa,Tree turnover,Treefall dynamics},
number = {11},
pages = {1211--1217},
title = {{Landscape-scale effects of herbivores on treefall in African savannas}},
volume = {15},
year = {2012}
}
@article{asner2011remote,
author = {Asner, Gregory P. and Levick, Shaun R. and Smit, Izak P.J.},
doi = {10.1201/b10275},
isbn = {9781439804711},
journal = {Ecosystem Function in Savannas: Measurement and Modeling at Landscape to Global Scales},
pages = {195--217},
title = {{Remote sensing of fractional cover and biochemistry in Savannas}},
year = {2010}
}
@article{Asner2016,
abstract = {Natural protected areas are critically important in the effort to prevent large-scale megafaunal extinctions caused by hunt- ing and habitat degradation. Yet such protection can lead to rapid increases in megafauna populations. Understanding ecosystem-scale responses of vegetation to changing megafaunal populations, such as the case of the African elephant Loxodonta africana in savannas, requires large-scale, high-resolution monitoring over time. From 2008 to 2014, we repeat- edly surveyed the fate of more than 10.4 million woody plant canopies throughout the Kruger National Park, South Africa using airborne Light Detection and Ranging (LiDAR), to determine the relative importance of multiple environmental, biotic and management factors affecting treefall rates and patterns. We report a mean biennial treefall rate of 8 trees or 12{\%} ha?1, but with heterogeneous patterns of loss in both space and time. Throughout Kruger, the influence of elephant density on treefall was matched only by spatial variation in soils and elevation, and all three factors co-dominated park- wide treefall patterns. Elephant density was up to two times more influential than fire frequency in determining treefall rates, and this pattern was most pronounced for taller trees (?2 m in height). Our results suggest that confining mega- fauna populations to protected areas, or reintroducing them into former or new habitat, can greatly alter the structure and functioning of the host ecosystem. Conservation strategies will need to accommodate and manage these massive ecological changes in the effort to save megafauna from extinction, without compromising system functionality.},
author = {Asner, Gregory P. and Vaughn, Nicholas and Smit, Izak P.J. and Levick, Shaun},
doi = {10.1111/ecog.01640},
isbn = {1600-0587},
issn = {16000587},
journal = {Ecography},
number = {2},
pages = {240--252},
title = {{Ecosystem-scale effects of megafauna in African savannas}},
volume = {39},
year = {2016}
}
@article{Baldeck2014,
abstract = {Information on landscape-scale patterns in species distributions and community types is vital for ecological science and effective conservation assessment and planning. However, detailed maps of plant community structure at landscape scales seldom exist due to the inability of field-based inventories to map a sufficient number of individuals over large areas. The Carnegie Airborne Observatory (CAO) collected hyperspectral and lidar data over Kruger National Park, South Africa, and these data were used to remotely identify {\textgreater}500 000 tree and shrub crowns over a 144-km2 landscape using stacked support vector machines. Maps of community compositional variation were produced by ordination and clustering, and the importance of hillslope-scale topo-edaphic variation in shaping community structure was evaluated with redundancy analysis. This remote species identification approach revealed spatially complex patterns in woody plant communities throughout the landscape that could not be directly observed using field-based methods alone. We estimated that topo-edaphic variables representing catenal sequences explained 21{\%} of species compositional variation, while we also uncovered important community patterns that were unrelated to catenas, indicating a large role for other soil-related factors in shaping the savanna community. Our results demonstrate the ability of airborne species identification techniques to map biodiversity for the evaluation of ecological controls on community composition over large landscapes. {\textcopyright} 2014 by the Ecological Society of America.},
author = {Baldeck, C. A. and Colgan, M. S. and F{\'{e}}ret, J. B. and Levick, S. R. and Martin, R. E. and Asner, G. P.},
doi = {10.1890/13-0307.1},
issn = {10510761},
journal = {Ecological Applications},
keywords = {Biodiversity,Carnegie Airborne Observatory,Catena,Community,Imaging spectroscopy,Kruger National Park,Lidar,Remote sensing,Savanna,South Africa,Support vector machine},
number = {1},
pages = {84--93},
title = {{Landscape-scale variation in plant community composition of an African savanna from airborne species mapping}},
volume = {24},
year = {2014}
}
@article{beavan2012ground,
author = {Beavan, J and Levick, S R and Lee, J and Jones, K},
journal = {GNS science consultancy report},
pages = {44},
title = {{Ground displacements and dilatational strains caused by $\backslash$tthe 2010-2011 Canterbury earthquakes}},
url = {papers2://publication/uuid/61A4AC32-9759-44A8-AE94-B99C6D38661C},
volume = {Consultanc},
year = {2012}
}
@article{beetham2011assessment,
author = {Beetham, R D and Begg, J G and Barker, P and Levick, S R and Beetham, J},
journal = {New Zealand: GNS Science consultancy report},
number = {July},
pages = {90},
title = {{Assessment of liquefaction and related ground failure hazards in Palmerston North, New Zealand}},
url = {papers2://publication/uuid/9E4BB49B-F91A-4892-883D-3244FA4B37C4},
volume = {108},
year = {2011}
}
@article{brandoprolonged,
author = {Brando, Paulo M. and Silv{\'{e}}rio, Divino and Maracahipes-Santos, Leonardo and Oliveira-Santos, Claudinei and Levick, Shaun R. and Coe, Michael T. and Migliavacca, Mirco and Balch, Jennifer K. and Macedo, Marcia N. and Nepstad, Daniel C. and Maracahipes, Leandro and Davidson, Eric and Asner, Gregory and Kolle, Olaf and Trumbore, Susan},
doi = {10.1111/gcb.14659},
issn = {13541013},
journal = {Global Change Biology},
title = {{Prolonged tropical forest degradation due to compounding disturbances: Implications for CO2 and H2O fluxes}},
url = {http://doi.wiley.com/10.1111/gcb.14659},
year = {2019}
}
@article{Chadwick2013,
abstract = {The spacing of hills and valleys reflects the competition between disturbance-driven (or diffusive) transport on hillslopes and concentrative (or advective) transport in valleys, although the underlying lithologic, tectonic, and climatic controls have not been untangled. Here, we measure geochemical and geomorphic properties of catchments in Kruger National Park, South Africa, where granitic lithology and erosion rates are invariant, enabling us to evaluate how varying mean annual precipitation (MAP = 470 mm, 550 mm, and 730 mm) impacts hill-valley spacing or landscape dissection. Catchment-averaged erosion rates, based on 10Be concentrations in river sands, are low (3–6 m/m.y.) and vary minimally across the three sites. Our lidar-derived slope-area analyses reveal that hillslopes in the dry site are gentle (3{\%}) and short, such that the terrain is low relief and appears highly dissected. With increasing rainfall, hillslopes lengthen and increase in gradient (6{\%}–8{\%}), resulting in less-dissected, higher-relief catchments. The chemical depletion fraction of hilltop regoliths increases with rainfall, from 0.3 to 0.7, reflecting a climate-driven increase in chemical relative to physical erosion. Soil catenas also vary systematically with climate as we observe relatively uniform soil properties in the dry site that contrast with leached sandy crests and upper slopes coupled with downslope clay accumulation zones in the intermediate and wet sites. The geomorphic texture of this slow-eroding, granitic landscape appears to be set by climate-driven feedbacks among chemical weathering, regolith fabric differentiation, hydrological routing, and sediment transport that enhance the vigor of hillslope sediment transport relative to valley-forming processes for wetter climates.},
author = {Chadwick, Oliver A. and Roering, Josh J. and Heimsath, Arjun M. and Levick, Shaun R. and Asner, Gregory P. and Khomo, Lesego},
doi = {10.1130/G34721.1},
issn = {00917613},
journal = {Geology},
number = {11},
pages = {1171--1174},
title = {{Shaping post-orogenic landscapes by climate and chemical weathering}},
volume = {41},
year = {2013}
}
@article{Cobb2017,
abstract = {Broad-scale forest die-off associated with drought and heat has now been reported from every forested continent, posing a global-scale challenge to forest management. Climate-driven die-off is frequently compounded with other drivers of tree mortality, such as altered land use, wildfire, and invasive species, making forest management increasingly complex. Facing similar challenges, rangeland managers have widely adopted the approach of developing conceptual models that identify key ecosystem states and major types of transitions between those states, known as "state-and-transition models" (S{\&}T models). Using expert opinion and available research, the development of such conceptual S{\&}T models has proven useful in anticipating ecosystem changes and identifying management actions to undertake or to avoid. In cases where detailed data are available, S{\&}T models can be developed into probabilistic predictions, but even where data are insufficient to predict transition probabilities, conceptual S{\&}T models can provide valuable insights for managing a given ecosystem and for comparing and contrasting different ecosystem dynamics. We assembled a synthesis of 14 forest die-off case studies from around the globe, each with sufficient information to infer impacts on forest dynamics and to inform management options following a forest die-off event. For each, we developed a conceptual S{\&}T model to identify alternative ecosystem states, pathways of ecosystem change, and points where management interventions have been, or may be, successful in arresting or reversing undesirable changes. We found that our diverse set of mortality case studies fit into three broad classes of ecosystem trajectories: (1) single-state transition shifts, (2) ecological cascading responses and feedbacks, and (3) complex dynamics where multiple interactions, mortality drivers, and impacts create a range of possible state transition responses. We integrate monitoring and management goals in a framework aimed to facilitate development of conceptual S{\&}T models for other forest die-off events. Our results highlight that although forest die-off events across the globe encompass many different underlying drivers and pathways of ecosystem change, there are commonalities in opportunities for successful management intervention.},
author = {Cobb, Richard C. and Ruthrof, Katinka X. and Breshears, David D. and Lloret, Francisco and Aakala, Tuomas and Adams, Henry D. and Anderegg, William R. and Ewers, Brent E. and Galiano, Luc Ia and Grcunzweig, Jose M. and Hartmann, Henrik and Huang, Cho Ying and Klein, Tamir and Kunert, Norbert and Kitzberger, Thomas and Landhcausser, Simon M. and Levick, Shaun and Preisler, Yakir and Suarez, Maria L. and Trotsiuk, Volodymyr and Zeppel, Melanie J.B.},
doi = {10.1002/ecs2.2034},
issn = {21508925},
journal = {Ecosphere},
keywords = {Climate Change,Conceptual State-And-Transition Models,Drought,Fire,Forest Management,Pests And Pathogens,Tree Die-Off},
number = {12},
title = {{Ecosystem dynamics and management after forest Die-Off: A global synthesis with conceptual state-and-transition models}},
volume = {8},
year = {2017}
}
@article{Colgan2012,
abstract = {The distribution of woody biomass in savannas reflects spatial patterns fundamental to ecosystem processes, such as water flow, competition, and herbivory, and is a key contributor to savanna ecosystem services, such as fuelwood supply. While total precipitation sets an upper bound on savanna woody biomass, the extent to which substrate and terrain constrain trees and shrubs below this maximum remains poorly understood, often occluded by local-scale disturbances such as fire and trampling. Here we investigate the role of hillslope topography and soil properties in controlling woody plant aboveground biomass (AGB) in Kruger National Park, South Africa. Large-area sampling with airborne Light Detection and Ranging (LiDAR) provided a means to average across local-scale disturbances, revealing an unexpectedly linear relationship between AGB and hillslope-position on basalts, where biomass levels were lowest on crests, and linearly increased toward streams (R2 = 0.91). The observed pattern was different on granite substrates, where AGB exhibited a strongly non-linear relationship with hillslope position: AGB was high on crests, decreased midslope, and then increased near stream channels (R2 = 0.87). Overall, we observed 5-to-8-fold lower AGB on clayey, basalt-derived soil than on granites, and we suggest this is due to herbivore-fire interactions rather than lower hydraulic conductivity or clay shrinkage/swelling, as previously hypothesized. By mapping AGB within and outside fire and herbivore exclosures, we found that basalt-derived soils support tenfold higher AGB in the absence of fire and herbivory, suggesting high clay content alone is not a proximal limitation on AGB. Understanding how fire and herbivory contribute to AGB heterogeneity is critical to predicting future savanna carbon storage under a changing climate.},
author = {Colgan, M. S. and Asner, G. P. and Levick, S. R. and Martin, R. E. and Chadwick, O. A.},
doi = {10.5194/bg-9-1809-2012},
issn = {17264170},
journal = {Biogeosciences},
number = {5},
pages = {1809--1821},
title = {{Topo-edaphic controls over woody plant biomass in South African savannas}},
volume = {9},
year = {2012}
}
@article{Davies2014a,
abstract = {Termite mounds contribute to the spatial heterogeneity of ecological processes in many savannas, but the underlying patterns and determinants of mound distributions remain poorly understood. Using the Carnegie Airborne Observatory (CAO), we mapped the distribution of termite mounds across a rainfall gradient within a river catchment (similar to 27 000 ha) of the Kruger National Park, South Africa. We assessed how different factors were associated with the distribution and height of termite mounds at three spatial scales: the entire catchment, among three broad vegetation types, and on individual hillslope crests. Abiotic factors such as the underlying geology and mean annual precipitation shaped mound densities at broad scales, while local hillslope morphology strongly influenced mound distribution at finer scales, emphasising the importance of spatial scale when assessing mound densities. Fire return period had no apparent association with mound densities or height. Mound density averaged 0.46 mounds ha(-1), and exhibited a clustered pattern throughout the landscape, occurring at relatively high densities (up to 2 mounds ha(-1)) on crests, which are nutrient-poor elements of the landscape. Mounds exhibited significant over-dispersion (even spacing) at scales below 60 m so that evenly spaced aggregations of termite mounds are embedded within a landscape of varying mound densities. The tallest mounds were found in dry savanna (500 mm yr(-1)) and were positively correlated with mound density, suggesting that dry granitic savannas are ideal habitat for mound-building termites. Mound activity status also varied significantly across the rainfall gradient, with a higher proportion of active (live) mounds in the drier sites. The differential spacing of mounds across landscapes provides essential nutrient hotspots in crest locations, potentially sustaining species that would otherwise not persist. The contribution to biodiversity and ecosystem functioning that mounds provide is not uniform throughout landscapes, but varies considerably with spatial scale and context.},
author = {Davies, Andrew B. and Levick, Shaun R. and Asner, Gregory P. and Robertson, Mark P. and van Rensburg, Berndt J. and Parr, Catherine L.},
doi = {10.1111/ecog.00532},
issn = {16000587},
journal = {Ecography},
number = {9},
pages = {852--862},
title = {{Spatial variability and abiotic determinants of termite mounds throughout a savanna catchment}},
volume = {37},
year = {2014}
}
@article{Davies2016a,
abstract = {Herbivores do not forage uniformly across landscapes, but select for patches of higher nutrition and lower predation risk. Macrotermes mounds contain higher concentrations of soil nutrients and support grasses of higher nutritional value than the surrounding savanna matrix, attracting mammalian grazers that preferentially forage on termite mound vegetation. However, little is known about the spatial extent of such termite influence on grazing patterns and how it might differ in time and space. We measured grazing intensity in three African savanna types differing in rainfall and foliar nutrients and predicted that the functional importance of mounds for grazing herbivores would increase as the difference in foliar nutrient levels between mound and savanna matrix grasses increases and the mounds become more attractive. We expected this to occur in nutrient-poor areas and during the dry season when savanna matrix grass nutrient levels are lower. Tuft use and grass N and P content were measured along transects away from termite mounds, enabling calculation of the spatial extent of termite influence on mammalian grazing. Using termite mound densities estimated from airborne light detection and ranging (LiDAR), we further upscaled field-based results to determine the percentage of the landscape influenced by termite activity. Grasses in close proximity to termite mounds were preferentially grazed at all sites and in both seasons, but the strength of mound influence varied between savanna types and seasons. In the wet season, mounds had a relatively larger effect on grazers at the landscape scale in the nutrient- poor, wetter savanna, whereas in the dry season the pattern was reversed with more of the landscape influenced at the nutrient-rich, driest site. Our results reveal that termite mounds enhance the value of savanna landscapes for herbivores, but that their functional importance varies across savanna types and seasons.},
author = {Davies, Andrew B. and Levick, Shaun R. and Robertson, Mark P. and van Rensburg, Berndt J. and Asner, Gregory P. and Parr, Catherine L.},
doi = {10.1111/oik.02742},
issn = {16000706},
journal = {Oikos},
number = {5},
pages = {726--734},
title = {{Termite mounds differ in their importance for herbivores across savanna types, seasons and spatial scales}},
volume = {125},
year = {2016}
}
@article{davies2014variable,
abstract = {Questions: Termite mounds of the genus Macrotermes are prominent features in African savannas, forming nutrient hotspots that support greater plant diversity, which is of higher nutritional value than the surrounding savanna matrix. However, little is known about grass communities on and around mounds or how the functional importance of mounds varies across sites. As mean annual rainfall increases, savannas in southern Africa become increasingly dystrophic through increased denitrification (including pyrodenitrification) and the leaching of soil nutrients. The functional importance of mounds is concomitantly expected to increase as the difference in foliar nutrient levels between mounds and the savanna matrix increases. We tested this prediction on grass communities across a rainfall gradient to: (i) determine the degree to which grass assemblages differ between termite mounds and the savanna matrix; (ii) determine the spatial extent to which mounds influence grass communities; and (iii) investigate whether these patterns differ across savanna types. Location: Kruger National Park, South Africa. Methods: Grass communities were surveyed at three savanna sites differing in mean annual rainfall (550-750mm center dot yr(-1)). Grass diversity and tissue nitrogen concentrations were measured on and off termite mounds and along transects away from mounds in order to calculate the spatial influence of termite mounds on savanna grass communities. Using termite mound densities estimated from airborne LiDAR, we up-scaled field-based results to determine the percentage of the landscape influenced by Macrotermes termite activity. Results: Although species richness of grasses was lower on mounds than in the savanna matrix, the assemblage composition varied significantly, with higher nutrient concentrations in grasses located on mounds. This pattern became more distinct with increasing rainfall. The spatial extent of these nutrient-rich grasses also differed across the rainfall gradient, with a larger sphere of influence around mounds in wetter areas. Mounds distinctly altered grass communities over ca. 2{\%} of the entire landscape. Conclusions: Our results show that Macrotermes mounds are important components of savanna heterogeneity, and reveal that the functional importance of mounds increases with increasing rainfall.},
author = {Davies, Andrew B. and Robertson, Mark P. and Levick, Shaun R. and Asner, Gregory P. and van Rensburg, Berndt J. and Parr, Catherine L.},
doi = {10.1111/jvs.12200},
issn = {16541103},
journal = {Journal of Vegetation Science},
keywords = {LiDAR,Macrotermes,Nutrients,Spatial heterogeneity,Species richness},
number = {6},
pages = {1405--1416},
title = {{Variable effects of termite mounds on African savanna grass communities across a rainfall gradient}},
volume = {25},
year = {2014}
}
@article{Davies2016,
abstract = {African savannas are highly seasonal with a diverse array of both mammalian and invertebrate herbivores, yet herbivory studies have focused almost exclusively on mammals. We conducted a two-year exclosure experiment in South Africa's Kruger National Park to measure the relative impact of these two groups of herbivores on grass removal at both highly productive patches (termite mounds) and in the less productive savanna matrix. Invertebrate and mammalian herbivory was greater on termite mounds, but the relative importance of each group changed over time. Mammalian offtake was higher than invertebrates in the dry season, but can be eclipsed by invertebrates during the wet season when this group is more active. Our results demonstrate that invertebrates play a substantial role in savanna herbivory and should not be disregarded in attempts to understand the impacts of herbivory on ecosystems. This article is protected by copyright. All rights reserved.},
author = {Davies, Andrew B. and {Van Rensburg}, Berndt J. and Robertson, Mark P. and Levick, Shaun R. and Asner, Gregory P. and Parr, Catherine L.},
doi = {10.1890/15-1905.1},
issn = {00129658},
journal = {Ecology},
keywords = {Exclosure experiments,Grasshoppers,Insect herbivory,Kruger national park,Macrotermes,Nutrients},
number = {6},
pages = {1618--1624},
title = {{Seasonal variation in the relative dominance of herbivore guilds in an African savanna}},
volume = {97},
year = {2016}
}
@article{Ehrle2017,
abstract = {The yellow-meadow ant (Lasius flavus) is a common mound-building species of central European grasslands. Lasius flavus activity has been shown to change the amounts of plant nutrients in their mound soil substrate. It is unknown how the maturity of such mounds influences nutrient status and affects plant growth. We quantified bulk soil and extractable nutrient contents of three mound development stages (young, middle-aged and fully-developed) in comparison to the surrounding soil (control), and in a bioassay using species of three plant functional types (grass, non nitrogen (N)-fixing forb, N-fixing forb) linked these to plant growth and chemistry. Our results showed that development stage was an important predictor of a mound's nutritional status. Lasius flavus activity results in decreases in bulk soil organic carbon, total nitrogen, sulfur, extractable manganese and zinc, and increases in bulk soil clay, pH, base cations, iron, phosphorous, boron, extractable calcium and potassium. The relative amounts of accumulated biomass, the proportion allocated to shoots or roots, and the N content of these tissues all differed among plant species. The N-fixing forb gained the highest total biomass and had the greatest allocation to shoots on soils of fully-developed mounds. The grass responded to all mound development stages with increased root biomass, whereas no effect was detected for the non N-fixing forb. The root N contents of the grass and the non N-fixing forb decreased with mound development stage. The findings highlight the importance of established L. flavus mounds as discrete micro-habitats in grassland ecosystems adding to biogeochemical heterogeneity.},
author = {Ehrle, Antje and Andersen, Alan N. and Levick, Shaun R. and Schumacher, Jens and Trumbore, Susan E. and Michalzik, Beate},
doi = {10.1016/j.ejsobi.2017.06.006},
issn = {11645563},
journal = {European Journal of Soil Biology},
keywords = {Bioassay,Cold water extracts,Micro habitats,Nutrient contents,Plant biomass},
pages = {83--93},
title = {{Yellow-meadow ant (Lasius flavus) mound development determines soil properties and growth responses of different plant functional types}},
volume = {81},
year = {2017}
}
@article{Goldbergs2018,
abstract = {Understanding the role that the vast north Australian savannas play in the continental carbon cycle requires reliable quantification of their carbon stock at landscape and regional scales. LiDAR remote sensing has proven efficient and accurate for the fine-scale estimation of above-ground tree biomass (AGB) and carbon stocks in many ecosystems, but tropical savanna remain under studied. We utilized a two-phase LiDAR analysis procedure which integrates both individual tree detection (ITC) and area-based approaches (ABA) to better understand how the uncertainty of biomass estimation varies with scale. We used estimations from individual tree LiDAR measurements as training/reference data, and then applied these data to develop allometric equations related to LIDAR metrics. We found that LiDAR individual tree heights were strongly correlated with field-estimated AGB (R2 = 0.754, RMSE = 90 kg), and that 63{\%} of individual trees crowns (ITC) could be accurately delineated with a canopy maxima approach. Area-based biomass estimation (ABA), which incorporated errors from the ITC steps, identified the quadratic mean of canopy height (QMCH) as the best single independent variable for different plot sample sizes (e.g. for 4 ha plots: R2 = 0.86, RMSE = 3.4 Mg ha− 1; and 1 ha plots: R2 = 0.83, RMSE = 4.0 Mg ha− 1). Our results show how ITC and ABA approached can be integrated to understand how biomass uncertainty varies with scale across broad landscapes. Understanding these scaling relationships is critical for operationalizing regional savanna inventories, monitoring and mapping.},
author = {Goldbergs, Grigorijs and Levick, Shaun R. and Lawes, Michael and Edwards, Andrew},
doi = {10.1016/j.rse.2017.11.010},
issn = {00344257},
journal = {Remote Sensing of Environment},
keywords = {Biomass,Carbon,LiDAR,Savanna,Tropics},
pages = {141--150},
title = {{Hierarchical integration of individual tree and area-based approaches for savanna biomass uncertainty estimation from airborne LiDAR}},
volume = {205},
year = {2018}
}
@article{Goldbergs2019,
abstract = {Obtaining reliable measures of tree canopy height across large areas is a central element of forest inventory and carbon accounting. Recent years have seen an increased emphasis on the use of active sensors like Radar and airborne LiDAR (light detection and scanning) systems to estimate various 3D characteristics of canopy and crown structure that can be used as predictors of biomass. However, airborne LiDAR data are expensive to acquire, and not often readily available across large remote landscapes. In this study, we evaluated the potential of stereo imagery from commercially available Very High Resolution (VHR) satellites as an alternative for estimating canopy height variables in Australian tropical savannas, using a semi-global dense matching (SGM) image-based technique. We assessed and compared the completeness and vertical accuracy of extracted canopy height models (CHMs) from GeoEye 1 and WorldView 1 VHR satellite stereo pairs and summarised the factors influencing image matching effectiveness and quality. Our results showed that stereo dense matching using the SGM technique severely underestimates tree presence and canopy height. The highest tree detection rates were achieved by using the near-infrared (NIR) band of GE1 (8–9{\%}). WV1-GE1 cross-satellite (mixed) models did not improve the quality of extracted canopy heights. We consider these poor detection rates and height retrievals to result from: i) the clumping crown structure of the dominant Eucalyptus spp.; ii) their vertically oriented leaves (affecting the bidirectional reflectance distribution function); iii) image band radiometry and iv) wind induced crown movement affecting stereo-pair point matching. Our detailed analyses suggest that current commercially available VHR satellite data (0.5 m resolution) are not well suited to estimating canopy height variables, and therefore above ground biomass (AGB), in Eucalyptus dominated north Australian tropical savanna woodlands.},
author = {Goldbergs, Grigorijs and Maier, Stefan W. and Levick, Shaun R. and Edwards, Andrew},
doi = {10.1016/j.jag.2018.10.021},
issn = {1872826X},
journal = {International Journal of Applied Earth Observation and Geoinformation},
keywords = {Canopy height,Satellite,Savanna,Stereo},
pages = {83--95},
title = {{Limitations of high resolution satellite stereo imagery for estimating canopy height in Australian tropical savannas}},
volume = {75},
year = {2019}
}
@article{Goldbergs2018a,
abstract = {The reliability of airborne light detection and ranging (LiDAR) for delineating individual trees and estimating aboveground biomass (AGB) has been proven in a diverse range of ecosystems, but can be difficult and costly to commission. Point clouds derived from structure from motion (SfM) matching techniques obtained from unmanned aerial systems (UAS) could be a feasible low-cost alternative to airborne LiDAR scanning for canopy parameter retrieval. This study assesses the extent to which SfM three-dimensional (3D) point clouds-obtained from a light-weight mini-UAS quadcopter with an inexpensive consumer action GoPro camera-can efficiently and effectively detect individual trees, measure tree heights, and provide AGB estimates in Australian tropical savannas. Two well-established canopy maxima and watershed segmentation tree detection algorithms were tested on canopy height models (CHM) derived from SfM imagery. The influence of CHM spatial resolution on tree detection accuracy was analysed, and the results were validated against existing high-resolution airborne LiDAR data. We found that the canopy maxima and watershed segmentation routines produced similar tree detection rates ({\~{}}70{\%}) for dominant and co-dominant trees, but yielded low detection rates ( {\textless} 35{\%}) for suppressed and small trees due to poor representativeness in point clouds and overstory occlusion. Although airborne LiDAR provides higher tree detection rates and more accurate estimates of tree heights, we found SfM image matching to be an adequate low-cost alternative for the detection of dominant and co-dominant tree stands.},
author = {Goldbergs, Grigorijs and Maier, Stefan W. and Levick, Shaun R. and Edwards, Andrew},
doi = {10.3390/rs10020161},
issn = {20724292},
journal = {Remote Sensing},
keywords = {Biomass,Canopy height,Low-cost UAS,Segmentation,Single tree detection,Structure frommotion},
number = {2},
title = {{Efficiency of individual tree detection approaches based on light-weight and low-cost UAS imagery in Australian Savannas}},
volume = {10},
year = {2018}
}
@article{Gossner2016,
abstract = {Modification of natural ecosystems has threatened biodiversity worldwide, with forests suffering especially. Strategies aimed at mitigating such loss in forests often include enrichment of deadwood, a critical resource for many decomposer species. However, it remains unclear how deadwood can best be enriched to most effectively promote the diversity of saproxylic species. In this study, we investigated saproxylic beetle diversity in experimentally exposed deadwood logs of 13 different tree species across 30 forests in three regions of Germany. We tested whether gamma-diversity differs between tree species and whether the alpha-diversity within an individual log depended on whether logs were placed in unmanaged beech forests, managed beech forests, or managed conifer forests. We found significant differences in gamma- and alpha-diversity of saproxylic beetles among tree species, but the ranking of tree species differed between regions, suggesting differences in regional beetle species pools. Randomization tests aiming to identify how many and which deadwood logs would need to be exposed to best conserve saproxylic beetle diversity, showed that the overall diversity of beetles increased with the number of tree species exposed, due to turnover of beetle species between tree species. However, some species (e.g. Carpinus) and species combinations (e.g. Carpinus-Picea) reached exceptionally high beetle diversity. Alpha-diversity was higher in conifer than in beech forests, but did not differ between managed and unmanaged beech forests. Canopy cover above logs and average stand temperature strongly influenced alpha-diversity, suggesting that environmental conditions that may be affected by management act as habitat filters for species assemblages. We conclude that deadwood enrichment strategies would be most effective when combining particular tree species that support highest diversity.},
author = {Gossner, Martin M. and Wende, Beate and Levick, Shaun and Schall, Peter and Floren, Andreas and Linsenmair, Karl Eduard and Steffan-Dewenter, Ingolf and Schulze, Ernst Detlef and Weisser, Wolfgang W.},
doi = {10.1016/j.biocon.2016.06.032},
issn = {00063207},
journal = {Biological Conservation},
keywords = {Coleoptera,Decomposition,Environmental filter,Experiment,Host specificity,LiDAR},
pages = {92--102},
title = {{Deadwood enrichment in European forests – Which tree species should be used to promote saproxylic beetle diversity?}},
volume = {201},
year = {2016}
}
@misc{Joyce2014,
abstract = {Geological hazards and their effects are often geographically widespread. Consequently, their effective mapping and monitoring is best conducted using satellite and airborne imaging platforms to obtain broad scale, synoptic coverage. With a multitude of hazards and effects, potential data types, and processing techniques, it can be challenging to determine the best approach for mapping and monitoring. It is therefore critical to understand the spatial and temporal effects of any particular hazard on the environment before selecting the most appropriate data type/s and processing techniques to apply. This review is designed to assist the decision-making and selection process when embarking on a hazard mapping or monitoring exercise. It focuses on the application of optical, LiDAR, and synthetic aperture RADAR technologies for the assessment of pre-event risk and post-event damage. Geological hazards of global interest summarized here are landslides and erosion; seismic and tectonic hazards; ground subsidence; and flooding and tsunami. {\textcopyright} 2014 Springer Science+Business Media Dordrecht.},
author = {Joyce, K. E. and Samsonov, S. V. and Levick, S. R. and Engelbrecht, J. and Belliss, S.},
booktitle = {Natural Hazards},
doi = {10.1007/s11069-014-1122-7},
issn = {0921030X},
keywords = {Data acquisition,Geohazards,Image processing,Remote sensing},
number = {2},
pages = {137--163},
title = {{Mapping and monitoring geological hazards using optical, LiDAR, and synthetic aperture RADAR image data}},
volume = {73},
year = {2014}
}
@article{Kroger2009,
abstract = {Landscapes commonly comprise of mosaics, patches and boundaries. Riparian boundaries are complex to delineate and characterize, with a multitude of variables available for delineation. Multiple methods exist for boundary delineation such as two-dimensional wombling, constrained classification techniques and discontinuity detection. One method that has proven to be reliable in boundary delineation with one-dimensional transect data is the moving split window (MSW) analysis. This study demonstrates the efficacy of MSW to delineate grass species turnover and environmental boundaries across two geologically dissimilar riparian zones in the Kruger National Park, South Africa. There are few studies that have delineated riparian boundaries of Kruger National Park, and none that have used the MSW analysis. MSW detects significant changes in dissimilarity indices of variables along gradients. Significant shifts in dissimilarity designate boundaries at various spatial scales dictated by window sizes. Significant boundaries emerge by altering window sizes, increasing quadrat width and removing infrequent herbaceous species. By utilizing these three methods, MSW background variance was reduced and riparian and wetland/upland boundaries were sharper and more easily defined. {\textcopyright} 2009 Elsevier Masson SAS. All rights reserved.},
author = {Kr{\"{o}}ger, Robert and Khomo, Lesego M. and Levick, Shaun and Rogers, Kevin H.},
doi = {10.1016/j.actao.2009.05.007},
issn = {1146609X},
journal = {Acta Oecologica},
keywords = {Boundary,Delineation,Kruger National Park,Vegetation},
number = {5},
pages = {573--580},
title = {{Moving window analysis and riparian boundary delineation on the Northern Plains of Kruger National Park, South Africa}},
volume = {35},
year = {2009}
}
@article{draguct2010esp,
author = {L, Drăguţ and D, Tiede and R, Levick S.},
journal = {International Journal of Geographical Information Science},
number = {6},
pages = {859},
publisher = {Taylor {\&} Francis},
title = {{ESP: A Tool to Estimate Scale Parameter for Multiresolution Image Segmentation of Remotely Sensed Data.”}},
volume = {24},
year = {2010}
}
@article{Levick2006,
abstract = {Savannas are heterogeneous systems characterized by the coexistence of grasses and woody trees. Riparian zones are dynamic parts of savanna landscapes with structurally diverse woody vegetation. Growing recognition of the importance of the structural component of biodiversity has highlighted the need to understand the spatial distribution and temporal dynamics of woody structural diversity. Most studies of temporal change in savannas have employed the use of satellite imagery or black and white aerial photography. These techniques are useful for examining changes in woody cover over time, but cannot portray the threedimensional structure of vegetation. Advances in {\{}LiDAR{\}} technology have enabled three-dimensional information of vegetation to be obtained remotely over large areas. Whilst the use of {\{}LiDAR{\}} has gained considerable momentum in forested areas there has been limited application to savanna systems. We explore the applicability of {\{}LiDAR{\}} and object-based image analysis to the monitoring of woody structural diversity in a savanna system. {\{}LiDAR{\}} and colour aerial photography were acquired for the riparian and adjacent upland zones of four main rivers of the Shingwedzi Catchment - Kruger Park, South Africa. The resulting imagery, ground elevation and tree canopy elevation data covered an area of 635km2. The tree canopy surface and colour imagery were segmented at two scales with object-based image analysis algorithms {\{}(eCognition{\}} v4.0) to construct a patch hierarchy. A classification hierarchy was constructed with fuzzy logic membership rules derived from field data. Height, elevation and spectral data were used to distinguish different vegetation types from bare ground. Results suggest that {\{}LiDAR{\}} can reliably return vegetation height and crown diameter data in savanna systems. The inclusion of object-based image analysis is an important step in fusing height data with colour imagery and generating multi-scale outputs. This approach provides a means for monitoring spatio-temporal changes in savanna woody vegetation structure at multiple scales.},
author = {Levick, S. R. and Rogers, K. H.},
journal = {International Archives for the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol. 34, Part XXX},
keywords = {biodiversity,conservation,ecognition,heterogeneity,lidar,monitoring,savanna,structure},
pages = {6},
title = {{LiDAR and object-based image analysis as tools for monitoring the structural diversity of savanna vegetation}},
year = {2006}
}
@incollection{Levick2008,
abstract = {Savannas are heterogeneous systems characterized by the coexistence of grasses and woody trees. Growing recognition of the importance of the structural component of biodiversity has highlighted the need to understand the spatial distribution and temporal dynamics of woody plant structural diversity. Advances in LiDAR technology have enabled three dimensional information of vegetation to be obtained remotely over large areas. Whilst the use of LiDAR has gained considerable momentum in forested areas there has been limited application to savanna systems. We explore the applicability of LiDAR and object-based image analysis to the monitoring of woody structural diversity in a savanna system. We demonstrate how an object-based approach to image analysis significantly improves the accuracy of woody layer classification form in a heterogeneous landscape. Furthermore we illustrate how standard approaches to LiDAR derived canopy models suffer from interpolation artifacts in savannas, due to the heterogeneity of the woody layer. By integrating LiDAR with high resolution aerial photography, through object-based analysis, these artifacts can be removed to produce a robust canopy model. The object-based integration of LiDAR with aerial imagery holds immense potential for structural diversity monitoring in savannas.},
author = {Levick, S.R. and Rogers, K.H.},
booktitle = {Object-Based Image Analysis},
doi = {10.1007/978-3-540-77058-9_26},
pages = {477--491},
title = {{Structural biodiversity monitoring in savanna ecosystems: Integrating LiDAR and high resolution imagery through object-based image analysis}},
year = {2008}
}
@article{Levick2013,
abstract = {Loss of large trees in savanna parks is of biodiversity conservation concern as trees contribute substantially to system biomass, heterogeneity and ecological functioning. Using airborne light detection and ranging (LiDAR), we monitored 119,775 individual trees in two floristically distinct savanna river catchments (2400ha) over a 2-year period in the Kruger National Park, South Africa. Tree height was unchanged in 77{\%} of monitored trees, but 5{\%} increased and 18{\%} decreased in height by 1m or more. We identified 12,703 trees (10.6{\%}) that were completely toppled during the study period. The average rate of treefall was 2.6 trees ha-1yr-1, and was higher in a river catchment dominated by Acacia species (3.8 trees ha-1yr-1) than in another comprised primarily of Combretum species (2.1 trees ha-1yr-1). The majority of observed treefalls were in the 4-6m height classes where proportions of treefall reached 20{\%}. Spatial patterns of treefall were significantly clustered across the landscapes, with proportional rates of loss exceeding 30{\%} in some hillslope patches. These high rates of tree loss present a challenge to biodiversity conservation and management, as tall tree populations may struggle to persist if these rates are maintained over longer time scales. Field-based measures of species-specific population dynamics need to be coupled with large-scale airborne measurements to provide conservation managers with an integrated view upon which to base decision-making. {\textcopyright} 2012 Elsevier Ltd.},
author = {Levick, Shaun R. and Asner, Gregory P.},
doi = {10.1016/j.biocon.2012.07.009},
issn = {00063207},
journal = {Biological Conservation},
keywords = {Biodiversity,Dynamics,Elephant,Kruger National Park,LiDAR,South Africa,Spatial,Treefall},
pages = {121--127},
title = {{The rate and spatial pattern of treefall in a savanna landscape}},
volume = {157},
year = {2013}
}
@article{Levick2010,
abstract = {Global vegetation models predict the spread of woody vegetation in African savannas and grasslands under future climate scenarios, but they operate too broadly to consider hillslope-scale variations in tree-grass distribution. Topographically linked hydrology-soil-vegetation sequences, or catenas, underpin a variety of ecological processes in savannas, including responses to climate change. In this study, we explore the three-dimensional structure of hillslopes and vegetation, using high-resolution airborne LiDAR (Light Detection And Ranging), to understand the long-term effects of mean annual precipitation (MAP) on catena pattern. Our results reveal that the presence and position of hillslope hydrological boundaries, or seeplines, vary as a function of MAP through its long-term influence on clay redistribution. We suggest that changes in climate will differentially alter the structure of savannas through hydrological changes to the seasonally saturated grasslands downslope of seeplines. The mechanisms underlying future woody encroachment are not simply physiological responses to elevated temperatures and CO(2) levels but also involve hydrogeomorphological processes at the hillslope scale.},
author = {Levick, Shaun R. and Asner, Gregory P. and Chadwick, Oliver A. and Khomo, Lesego M. and Rogers, Kevin H. and Hartshorn, Anthony S. and Kennedy-Bowdoin, Ty and Knapp, David E.},
doi = {10.1038/ncomms1066},
issn = {20411723},
journal = {Nature Communications},
number = {6},
pages = {1--7},
title = {{Regional insight into savanna hydrogeomorphology from termite mounds}},
volume = {1},
year = {2010}
}
@article{Levick2009,
abstract = {The relative importance of fire and herbivory on vegetation structure has been the subject of much debate in savanna ecology. Fire regime and herbivore numbers are two key variables that managers of protected areas can manipulate to meet their conservation objectives. We deployed a new airborne remote sensing system (Carnegie Airborne Observatory) to the Kruger National Park (KNP), South Africa, to map a unique herbivore/fire exclusion experiment on basaltic soils. We collected high resolution (56 cm) three-dimensional (3-D) vegetation structural data over areas that have been protected from herbivores (34 yr) and/or fire (7 yr), as well as those exposed to both disturbance agents. Canopy height distribution, as well as the distribution of foliage within the vertical canopy profile, differed significantly between all treatments and between each treatment and the control area (Kolmogorov-Smirnov, p {\textless} 0.001). Herbivory exerted a greater influence on vegetation 3-D structure and heterogeneity than did fire. At the broad scale, total percentage woody cover was 36 times greater in areas protected from herbivores, compared to the control area. At a finer scale, areas protected from herbivores contained 5 times more tall tree canopy ({\textgreater}9 m) and up to 66 times more small tree canopy (3-6 m). Fire restricted growth of vegetation in the 0-3 m height range, both in the absence and presence of herbivores. Our findings highlight the active role that conservation managers can play in modifying vegetation structure and heterogeneity through herbivore and fire management, as well as the value of 3-D remote sensing for the assessment of conservation management outcomes. {\textcopyright} 2009 Elsevier Ltd. All rights reserved.},
author = {Levick, Shaun R. and Asner, Gregory P. and Kennedy-Bowdoin, Ty and Knapp, David E.},
doi = {10.1016/j.biocon.2009.03.004},
file = {::},
isbn = {0006-3207},
issn = {00063207},
journal = {Biological Conservation},
keywords = {Carnegie airborne observatory,Conservation,Heterogeneity,LiDAR,Management,Thresholds of potential concern},
number = {8},
pages = {1693--1700},
title = {{The relative influence of fire and herbivory on savanna three-dimensional vegetation structure}},
url = {http://www.sciencedirect.com/science/article/pii/S0006320709001232},
volume = {142},
year = {2009}
}
@article{Levick2010a,
abstract = {Termite mounds form islands of fertility in savanna landscapes and create foraging hotspots for herbivores, but the magnitude and spatial extent of these influences is unknown. We mapped terrain, termite mound and woody vegetation three-dimensional (3-D) structure at 56cm resolution across a large-scale (254ha), long-term (34 years) herbivore exclusion experiment in the Kruger National Park, with the Carnegie Airborne Observatory (CAO). We compared vegetation 3-D structure in areas protected from herbivores with those accessible to herbivores, both on termite mounds and in the landscape matrix between termite mounds. Termite mound density was 1.1ha -1 across the study area and mound size did not differ between protected and accessible areas. Woody vegetation canopy cover was ∼100{\%} greater on protected than accessible mounds, but was only ∼20{\%} greater in the protected inter-mound matrix when compared to the accessible matrix. Woody canopy height class distributions differed significantly between protected and accessible areas, with the tallest vegetation ({\textgreater}10m) occurring on protected termite mounds. The impacts of herbivore browsing were evident at distances of up to 20m from termite mound centres. Spatial analysis of mound distribution revealed that the sphere of termite mound influence constitutes ∼20{\%} of the total landscape. Termite influences on herbivore browsing operate at scales much larger than the spatial extent of their mound building activities. {\textcopyright} 2010 Elsevier Ltd.},
author = {Levick, Shaun R. and Asner, Gregory P. and Kennedy-Bowdoin, Ty and Knapp, David E.},
doi = {10.1016/j.biocon.2010.06.012},
issn = {00063207},
journal = {Biological Conservation},
keywords = {Foraging,Herbivory,LiDAR,Savanna,Scale,Termite},
number = {11},
pages = {2462--2467},
title = {{The spatial extent of termite influences on herbivore browsing in an African savanna}},
volume = {143},
year = {2010}
}
@article{Levick2012,
abstract = {Understanding the causes and consequences of animal movements is of fundamental biological interest because any alteration in movement can have direct and indirect effects on ecosystem structure and function. It is also crucial for assisting spatial wildlife management under variable environmental change scenarios. Recent research has highlighted the need of quantifying individual variability in movement behavior and how it is generated by interactions between individual requirements and environmental conditions, to understand the emergence of population-level patterns. Using a multi-annual movement data set of 213 individual moose {\{}Alces alces ) across a latitudinal gradient (from 56° to 67° N) that spans over 1100 km of varying environmental conditions, we analyze the differences in individual and population-level movements. We tested the effect of climate, risk, and human presence in the landscape on moose movements. The variation in these factors explained the existence of multiple movements (migration, nomadism, dispersal, sedentary) among individuals and seven populations. Population differences primarily were related to latitudinal variation in snow depth and road density. Individuals showed both fixed and flexible behaviors across years, and were less likely to migrate with age in interaction with snow and roads. For the predominant movement strategy, migration, the distance, timing, and duration at all latitudes varied between years. Males traveled longer distances and began migrating later in spring than females. Our study provides strong quantitative evidence for the dynamics of animal movements in response to changes in environmental conditions along with varying risk from human influence across the landscape. For moose, given its wide distributional range, changes in the distribution and migratory behavior are expected under future warming scenario}},
author = {Levick, Shaun R. and Asner, Gregory P. and Smit, Izak P.J.},
doi = {10.1890/12-0178.1},
issn = {10510761},
journal = {Ecological Applications},
keywords = {Catena,Fire frequency,Heterogeneity,Kruger National Park,Landscape,LiDAR,Management,Savanna structure,South Africa,Topography},
number = {8},
pages = {2110--2121},
title = {{Spatial patterns in the effects of fire on savanna vegetation three-dimensional structure}},
volume = {22},
year = {2012}
}
@article{Levick2015a,
abstract = {Fire is a key determinant of woody vegetation structure in savanna ecosystems, acting both independently and synergistically through interactions with herbivores. Fire influences biodiversity and ecological functioning, but quantifying its effects on woody structure is challenging at both species and community scales. Deeper insight into fire effects, and fire–herbivore interactions, can be gained through the examination of species-specific demographic and dynamic changes occurring across areas with different fire regimes in the presence of large herbivores. We used the Carnegie Airborne Observatory (an integrated LiDAR and imaging spectroscopy system) to map woody tree structure, species and dynamics over a four-year interval across two adjacent savanna landscapes with contrasting fire histories in Kruger National Park, South Africa. A history of higher fire frequency was associated with reduced woody canopy cover (17{\%} vs. 23{\%}) and an increased overall rate of treefall (27{\%} vs. 18{\%}). The landscape with a history of higher fire frequency displayed a shift in woody canopy height distribution from a unimodal curve to a bimodal pattern at the community scale, with large reductions in height classes {\textless}7 m. Differences in tree height distributions and treefall rates across sites were underpinned by species-specific responses to fire frequency. Acacia nigrescens displayed the highest rates of treefall, most likely related to elephant activity, with losses exceeding 40{\%} in the 6- to 9-m height classes. Synthesis. Our findings indicate that fire history imparts demographic legacies not only on vegetation structure, but also on current vegetation dynamics. Current treefall rates of certain tree species are exacerbated by a history of higher fire frequency. Species-specific and context-conscious investigations are critical for elucidating the driving mechanisms underlying broader community patterns.},
author = {Levick, Shaun R. and Baldeck, Claire A. and Asner, Gregory P.},
doi = {10.1111/1365-2435.12306},
issn = {13652435},
journal = {Functional Ecology},
keywords = {Acacia,Biodiversity conservation,Elephant herbivory,Fire management,Kruger,LiDAR,Savanna structure,Treefall},
number = {1},
pages = {131--139},
title = {{Demographic legacies of fire history in an African savanna}},
volume = {29},
year = {2015}
}
@article{Levick2016,
abstract = {Background: Monitoring and managing carbon stocks in forested ecosystems requires accurate and repeatable quantification of the spatial distribution of wood volume at landscape to regional scales. Grid-based forest inventory networks have provided valuable records of forest structure and dynamics at individual plot scales, but in isolation they may not represent the carbon dynamics of heterogeneous landscapes encompassing diverse land-management strategies and site conditions. Airborne LiDAR has greatly enhanced forest structural characterisation and, in conjunction with field-based inventories, it provides avenues for monitoring carbon over broader spatial scales. Here we aim to enhance the integration of airborne LiDAR surveying with field-based inventories by exploring the effect of inventory plot size and number on the relationship between field-estimated and LiDAR-predicted wood volume in deciduous broad-leafed forest in central Germany. Results: Estimation of wood volume from airborne LiDAR was most robust (R2= 0.92, RMSE = 50.57 m3ha-1{\~{}}14.13 Mg C ha-1) when trained and tested with 1 ha experimental plot data (n = 50). Predictions based on a more extensive (n = 1100) plot network with considerably smaller (0.05 ha) plots were inferior (R2= 0.68, RMSE = 101.01 {\~{}}28.09 Mg C ha-1). Differences between the 1 and 0.05 ha volume models from LiDAR were negligible however at the scale of individual land-management units. Sample size permutation tests showed that increasing the number of inventory plots above 350 for the 0.05 ha plots returned no improvement in R2and RMSE variability of the LiDAR-predicted wood volume model. Conclusions: Our results from this study confirm the utility of LiDAR for estimating wood volume in deciduous broad-leafed forest, but highlight the challenges associated with field plot size and number in establishing robust relationships between airborne LiDAR and field derived wood volume. We are moving into a forest management era where field-inventory and airborne LiDAR are inextricably linked, and we encourage field inventory campaigns to strive for increased plot size and give greater attention to precise stem geolocation for better integration with remote sensing strategies.},
author = {Levick, Shaun R. and Hessenm{\"{o}}ller, Dominik and Schulze, E. Detlef},
doi = {10.1186/s13021-016-0048-7},
issn = {17500680},
journal = {Carbon Balance and Management},
keywords = {Broad-leafed,Carbon,Forest,Inventory,LiDAR,Temperate,Wood volume},
number = {1},
title = {{Scaling wood volume estimates from inventory plots to landscapes with airborne LiDAR in temperate deciduous forest}},
volume = {11},
year = {2016}
}
@article{Levick2019,
abstract = {Fire regimes across the globe have been altered through changes in land-use, land management and climate conditions. Understanding how these modified fire regimes impact vegetation structure and dynamics is essential for informed biodiversity conservation and carbon management in savanna ecosystems. We used a long-term fire experiment at the Territory Wildlife Park (TWP), northern Australia, to investigate the consequences of altered fire regimes for habitat structure and aboveground carbon storage. We mapped vegetation three-dimensional (3D) structure in high spatial resolution with airborne LiDAR, across 18 replicated 1ha plots of varying fire frequency and season treatments. We used LiDAR-derived canopy height and cover metrics to extrapolate field-based measures of woody biomass to the full extent of the experimental site (R2=0.82, RMSE=7.35tCha{\&}minus;1), and analysed differences in aboveground carbon storage and 3D structure among treatments. Woody canopy cover and biomass were highest in the absence of fire (76{\%} and 39.8tCha{\&}minus;1) and lowest in plots burnt late in the dry season on a biennial basis (42{\%} and 18.2tCha{\&}minus;1). Woody canopy vertical profiles differed among all six fire treatments, with greatest divergence in height classes 5m. Our results highlight the large extent to which fire management can shape 3D structural patterns in savanna landscapes, even over time frames as short as a decade. The structural profile changes shown here, and the quantification of carbon reduction under late dry season burning, have important implications for faunal habitat conservation and carbon sequestration/emission reduction initiatives in the region.},
author = {Levick, Shaun R. and Richards, Anna E. and Cook, Garry D. and Schatz, Jon and Guderle, Marcus and Williams, Richard J. and Subedi, Parash and Trumbore, Susan E. and Andersen, Alan N.},
doi = {10.5194/bg-16-1493-2019},
issn = {17264189},
journal = {Biogeosciences},
number = {7},
pages = {1493--1503},
title = {{Rapid response of habitat structure and above-ground carbon storage to altered fire regimes in tropical savanna}},
volume = {16},
year = {2019}
}
@article{Levick2011,
author = {Levick, Shaun R. and Rogers, Kevin H.},
doi = {10.1007/s10980-011-9578-2},
issn = {09212973},
journal = {Landscape Ecology},
keywords = {Context-dependency,Dynamics,Heterogeneity,Kruger National Park,LiDAR,Non-stationarity,Pattern-process,Savanna,Scale,South Africa,Spatial},
number = {4},
pages = {515--528},
title = {{Context-dependent vegetation dynamics in an African savanna}},
volume = {26},
year = {2011}
}
@article{Levick2015,
abstract = {The spread of an alien invasive grass (gamba grass—Andropogon gayanus) in the tropical savannas of Northern Australia is a major threat to habitat quality and biodiversity in the region, primarily through its influence on fire intensity. Effective control and eradication of this invader requires better insight into its spatial distribution and rate of spread to inform management actions. We used full-waveform airborne LiDAR to map areas of known A. gayanus invasion in the Batchelor region of the Northern Territory, Australia. Our stratified sampling campaign included wooded savanna areas with differing degrees of A. gayanus invasion and adjacent areas of native grass and woody tree mixtures. We used height and spatial contiguity based metrics to classify returns from A. gayanus and developed spatial representations of A. gayanus occurrence (1 m resolution) and canopy cover (10 m resolution). The cover classification proved robust against two independent field-based investigations at 500 m2 (R2 = 0.87, RMSE = 12.53) and 100 m2 (R2 = 0.79, RMSE = 14.13) scale. Our mapping results provide a solid benchmark for evaluating the rate and pattern of A. gayanus spread from future LiDAR campaigns. In addition, this high-resolution mapping can be used to inform satellite image analysis for the evaluation of A. gayanus invasion over broader regional scales. Our research highlights the huge potential that airborne LiDAR holds for facilitating the monitoring and management of savanna habitat condition.},
author = {Levick, Shaun R. and Setterfield, Samantha A. and Rossiter-Rachor, Natalie A. and Hutley, Lindsay B. and McMaster, Damien and Hacker, Jorg M.},
doi = {10.3390/rs70505117},
issn = {20724292},
journal = {Remote Sensing},
keywords = {Alien plant,Gamba grass,Invasion,LiDAR,Weed mapping},
number = {5},
pages = {5117--5132},
title = {{Monitoring the distribution and dynamics of an invasive grass in tropical savanna using airborne LiDAR}},
volume = {7},
year = {2015}
}
@Thesis{levick2008scaled,
author = {Levick, Shaun Robert},
booktitle = {PhD Thesis},
institution = {University of teh Witwatersrand},
title = {{A scaled , contextual perspective of woody structure and dynamics across a savanna riparian landscape}},
year = {2008}
}
@article{Levick2008a,
abstract = {The impact of browsers on the structure of woody vegetation has been well documented in savanna landscapes but the spatial distribution of these impacts is poorly understood. Savannas are structurally heterogeneous and the effects of browsers are unlikely to be evenly distributed across them. A mammalian exclosure in northern Kruger Park, South Africa, was used to explore the impacts of 15 years of browser exclusion on woody vegetation across a wetland/upland boundary. Woody patches inside the exclosure were taller than those outside of the exclosure and differential patch and species specific responses were observed within and without the exclosure. A boundary between upland and wetland patch types showed the greatest response to browser exclusion in terms of woody species composition, height and stem diameter. Browser impacts are not distributed evenly across the landscape, but are focused on certain patch and species types. Browsers have the potential to markedly alter system heterogeneity. Landscape heterogeneity is an integral component of biodiversity, but is often not explicitly dealt with in protected area management. Typically monitoring of vegetation change in conservation areas occurs at broad scales and would not detect the change in either the patch type or species specific responses identified in this study. We recommend that protected area managers adopt a multi-scaled, spatially explicit approach to monitoring change in the landscape. Boundaries between patch types provide valuable indicators of browser mediated changes. {\textcopyright} 2007 Elsevier Ltd. All rights reserved.},
author = {Levick, Shaun and Rogers, Kevin},
doi = {10.1016/j.biocon.2007.11.001},
issn = {00063207},
journal = {Biological Conservation},
keywords = {Boundary,Elephant,Monitoring,Savanna,Scale,Spatial},
number = {2},
pages = {489--498},
title = {{Patch and species specific responses of savanna woody vegetation to browser exclusion}},
volume = {141},
year = {2008}
}
@article{Ratcliffe2015,
abstract = {European beech forest with a variable admixture is one of the most important forest types in Central Europe. Growing evidence has demonstrated the positive effect of increased biodiversity on vital forest ecosystem functions and services such as productivity and nutrient cycling. Both complementarity in resource use and species identity are known to influence tree productivity but they have received relatively little attention in observational studies. Using a large dataset of repeat inventory trees in a near-natural deciduous forest in Central Germany we test whether tree diversity enhances tree productivity at the tree and the stand level, whilst accounting for tree size, tree vitality, local topography and the potentially confounding effects of spatial autocorrelation and negative growth estimates. Beech and hornbeam individual tree growth was sensitive to their neighbourhood diversity and composition whilst ash trees were only sensitive to the neighbourhood tree density. Neighbourhood complementarity effects were driven by differences in species' competitive strengths, whilst at the stand level productivity gains were primarily attributable to the density of ash and diversity effects were less prominent. We conclude that small-scale admixture with patches of different species promotes tree growth in European beech forest; congruent with current management plans for beech and hardwood forests.},
author = {Ratcliffe, Sophia and Holzwarth, Fr{\'{e}}d{\'{e}}ric and Nadrowski, Karin and Levick, Shaun and Wirth, Christian},
doi = {10.1016/j.foreco.2014.09.032},
issn = {03781127},
journal = {Forest Ecology and Management},
keywords = {Basal area increment,Competition index,Diversity-productivity,Neighbourhood diversity},
pages = {225--234},
title = {{Tree neighbourhood matters - tree species composition drives diversity-productivity patterns in a near-natural beech forest}},
volume = {335},
year = {2015}
}
@article{Rughoft2016,
abstract = {Savannas cover at least 13{\%} of the global terrestrial surface and are often nutrient limited, especially by nitrogen. To gain a better understanding of their microbial diversity and the microbial nitrogen cycling in savanna soils, soil samples were collected along a granitic and a basaltic catena in Kruger National Park (South Africa) to characterize their bacterial and archaeal composition and the genetic potential for nitrification. Although the basaltic soils were on average 5 times more nutrient rich than the granitic soils, all investigated savanna soil samples showed typically low nutrient availabilities, i.e., up to 38 times lower soil N or C contents than temperate grasslands. Illumina MiSeq amplicon sequencing revealed a unique soil bacterial community dominated by Actinobacteria (20-66{\%}), Chloroflexi (9-29{\%}), and Firmicutes (7-42{\%}) and an increase in the relative abundance of Actinobacteria with increasing soil nutrient content. The archaeal community reached up to 14{\%} of the total soil microbial community and was dominated by the thaumarchaeal Soil Crenarchaeotic Group (43-99.8{\%}), with a high fraction of sequences related to the ammonia-oxidizing genus Nitrosopshaera sp. Quantitative PCR targeting amoA genes encoding the alpha subunit of ammonia monooxygenase also revealed a high genetic potential for ammonia oxidation dominated by archaea ({\~{}}5 × 107 archaeal amoA gene copies g-1 soil vs. mostly {\textless} 7 × 104 bacterial amoA gene copies g-1 soil). Abundances of archaeal 16S rRNA and amoA genes were positively correlated with soil nitrate, N and C contents. Nitrospira sp. was detected as the most abundant group of nitrite oxidizing bacteria. The specific geochemical conditions and particle transport dynamics at the granitic catena were found to affect soil microbial communities through clay and nutrient relocation along the hill slope, causing a shift to different, less diverse bacterial and archaeal communities at the footslope. Overall, our results suggest a strong effect of the savanna soils' nutrient scarcity on all microbial communities, resulting in a distinct community structure that differs markedly from nutrient-rich, temperate grasslands, along with a high relevance of archaeal ammonia oxidation in savanna soils.},
author = {Rugh{\"{o}}ft, Saskia and Herrmann, Martina and Lazar, Cassandre S. and Cesarz, Simone and Levick, Shaun R. and Trumbore, Susan E. and K{\"{u}}sel, Kirsten},
doi = {10.3389/fmicb.2016.01638},
issn = {1664302X},
journal = {Frontiers in Microbiology},
keywords = {Ammonia-oxidizing archaea,Ammonia-oxidizing bacteria,AmoA,Basaltic bedrock,Granitic bedrock,Savanna soils},
number = {OCT},
title = {{Community composition and abundance of bacterial, archaeal and nitrifying populations in savanna soils on contrasting bedrock material in Kruger National Park, South Africa}},
volume = {7},
year = {2016}
}
@article{schulze2016seltene,
author = {Schulze, E.-D. and Boch, S and M{\"{u}}ller, J and Levick, S R and Schumacher, J},
journal = {AFZ/Der Wald},
pages = {35--38},
publisher = {Deutscher Landwirtschaftsverlag},
title = {{Seltene und gef{\"{a}}hrdete Pflanzen wachsen im Laubwald {\"{u}}berall}},
volume = {13},
year = {2016}
}
@article{Schwabe2015,
abstract = {Translocations and reintroductions are key elements for the population management of the critically endangered black rhino (Diceros bicornis, Linnaeus, 1758). In this study, we investigated the postrelease behaviour and habitat preferences of a black rhino starter group (n = 4) on the individual level. The animals were reintroduced to a fenced game reserve (87 km2) in North-Central Namibia 1 year prior to our study. We used camera traps and very high frequency (VHF) radiotelemetry to examine the animals' temporal and spatial behaviour over a period of 4 months at transition between wet and dry seasons. Our results underline a peak in drinking activity and waterhole visits occurring between 7 p.m. and 8 p.m. We found a shift in intensity in drinking activity during the period of the study. Satellite-based woody cover estimations only suggest positive correlations between the density of woody cover and favoured black rhino habitat types. Although the area seems suitable to facilitate breeding success of this starter group, it does not support a self-sustaining population. However, black rhinos were already successfully reintroduced to several additional fenced reserves in this region. The selective opening of fences in the future could help to enable genetic exchange between currently isolated groups of rhinos.},
author = {Schwabe, Fabian and G{\"{o}}ttert, Thomas and Starik, Nicole and Levick, Shaun R. and Zeller, Ulrich},
doi = {10.1111/aje.12245},
issn = {13652028},
journal = {African Journal of Ecology},
keywords = {Black rhino,Camera traps,Land use,Reintroduction},
number = {4},
pages = {531--539},
title = {{A study on the postrelease behaviour and habitat preferences of black rhinos (Diceros bicornis) reintroduced into a fenced reserve in Namibia}},
volume = {53},
year = {2015}
}
@article{silverio2019fire,
abstract = {Widespread degradation of tropical forests is caused by a variety of disturbances that interact in ways that are not well understood. To explore potential synergies between edge effects, fire and windstorm damage as causes of Amazonian forest degradation, we quantified vegetation responses to a 30-min, high-intensity windstorm that in 2012, swept through a large-scale fire experiment that borders an agricultural field. Our pre- and postwindstorm measurements include tree mortality rates and modes of death, above-ground biomass, and airborne LiDAR-based estimates of tree heights and canopy disturbance (i.e., number and size of gaps). The experimental area in the southeastern Amazonia includes three 50-ha plots established in 2004 that were unburned (Control), burned annually (B1yr), or burned at 3-year intervals (B3yr). The windstorm caused greater damage to trees ({\textgreater}10 cm DBH) in the burned plots (B1yr: 13 ± 9{\%} of 785 trees; B3yr: 17 ± 13{\%} of 433) than in the Control plot (8 ± 4{\%} of 2,300; ± CI). It substantially reduced vegetation height by 14{\%} in B1yr, 20{\%} in B3yr and 12{\%} in the Control plots, while it reduced above-ground biomass by 18{\%} of 77.7 Mg/ha (B1yr), 31{\%} of 56.6 (B3yr), and 15{\%} of 120 (Control). Tree damage was greatest near the agricultural field edge in all three plots, especially among large trees and in B3yr. Trunk snapping (70{\%}) and uprooting (20{\%}) were the most common modes of tree damage and mortality, with the height of trunk failure on the burned plots often corresponding with the height of historical fire scars. Of the windstorm-damaged trees, 80{\%} (B1yr), 90{\%} (B3yr), and 57{\%} (Control) were dead 4 years later. Trees that had crown damage experienced the least mortality (22{\%}–60{\%}), followed by those that were snapped (55{\%}–94{\%}) and uprooted (88{\%}–94{\%}). Synthesis. We demonstrate the synergistic effects of three kinds of disturbances on a tropical forest. Our results show that the effects of windstorms are exacerbated by prior degradation by fire and fragmentation. We highlight that understorey fires can produce long-lasting effects on tropical forests not only by directly killing trees but also by increasing tree vulnerability to wind damage due to fire scars and a more open canopy.},
author = {Silv{\'{e}}rio, Divino V. and Brando, Paulo M. and Bustamante, Mercedes M.C. and Putz, Francis E. and Marra, Daniel Magnabosco and Levick, Shaun R. and Trumbore, Susan E.},
doi = {10.1111/1365-2745.13076},
issn = {13652745},
journal = {Journal of Ecology},
keywords = {Amazonia,biomass loss,fire scar,forest degradation,forest dynamics,tree mortality,windstorms},
number = {2},
pages = {656--667},
title = {{Fire, fragmentation, and windstorms: A recipe for tropical forest degradation}},
volume = {107},
year = {2019}
}
@article{Singh2018,
abstract = {Fire plays an intrinsic role in shaping the biophysical attributes of savanna ecosystems. Savanna fires limit vegetation biomass below their climatically determined potential, but the magnitude of this effect and how it varies across heterogeneous landscapes are poorly understood. In this study, we explore woody tree structure and canopy characteristics across a fire manipulation experiment that has been maintained for 63 yr in South Africa's Kruger National Park. Our study design assessed three late dry-season fire regimes (biennial, triennial, and unburnt) across a precipitation gradient (737–496 mm/yr) spanning four different landscapes with a mixture of sandy and clay soils. We used terrestrial laser scanning (TLS) to quantify tree height, canopy cover, and aboveground carbon storage across the experimental treatments. Vegetation physiognomy was influenced by the interaction between landscape and fire frequency. In the absence of fire, woody height, cover, and biomass increased with increasing rainfall. The presence of fire acted to reduce structure and biomass as expected, but the magnitude of this effect increased with increasing rainfall. We found minimal difference between the effects of biennial or triennial burning—except at the wettest site where the triennial fire plots had half the biomass of those burnt biennially. The rainfall dependent fire–vegetation relationships shown here provide empirical quantification of top-down constraint by fire and highlight the challenges of predicting responses to disturbances in these inherently heterogeneous ecosystems. Robust quantification of 3D structure and dynamics through TLS will be useful for constraining carbon stock models and predicting trajectories of change under future climate and land-use conditions.},
author = {Singh, Jenia and Levick, Shaun R. and Guderle, Marcus and Schmullius, Christiane and Trumbore, Susan E.},
doi = {10.1002/ecs2.2514},
issn = {21508925},
journal = {Ecosphere},
keywords = {Kruger National Park,fire frequency,savanna,terrestrial laser scanning,vegetation structure},
number = {12},
title = {{Variability in fire-induced change to vegetation physiognomy and biomass in semi-arid savanna}},
volume = {9},
year = {2018}
}
@article{Thurner2014,
abstract = {Aim: To infer a forest carbon density map at 0.01° resolution from a radar remote sensing product for the estimation of carbon stocks in Northern Hemisphere boreal and temperate forests. Location The study area extends from 30° N to 80° N, covering three forest biomes – temperate broadleaf and mixed forests (TBMF), temperate conifer forests (TCF) and boreal forests (BFT) – over three continents (North America, Europe and Asia). Methods This study is based on a recently available growing stock volume (GSV) product retrieved from synthetic aperture radar data. Forest biomass and spatially explicit uncertainty estimates were derived from the GSV using existing databases of wood density and allometric relationships between biomass compartments (stem, branches, roots, foliage). We tested the resultant map against inventory-based biomass data from Russia, Europe and the USA prior to making intercontinent and interbiome carbon stock comparisons. Results Our derived carbon density map agrees well with inventory data at regional scales (r2 = 0.70–0.90). While 40.7 ± 15.7 petagram of carbon (Pg C) are stored in BFT, TBMF and TCF contain 24.5 ± 9.4 Pg C and 14.5 ± 4.8 Pg C, respectively. In terms of carbon density, we found 6.21 ± 2.07 kg C m−2 retained in TCF and 5.80 ± 2.21 kg C m−2 in TBMF, whereas BFT have a mean carbon density of 4.00 ± 1.54 kg C m−2. Indications of a higher carbon density in Europe compared with the other continents across each of the three biomes could not be proved to be significant. Main conclusions The presented carbon density and corresponding uncertainty map give an insight into the spatial patterns of biomass and stand as a new benchmark to improve carbon cycle models and carbon monitoring systems. In total, we found 79.8 ± 29.9 Pg C stored in northern boreal and temperate forests, with Asian BFT accounting for 22.1 ± 8.3 Pg C.},
author = {Thurner, Martin and Beer, Christian and Santoro, Maurizio and Carvalhais, Nuno and Wutzler, Thomas and Schepaschenko, Dmitry and Shvidenko, Anatoly and Kompter, Elisabeth and Ahrens, Bernhard and Levick, Shaun R. and Schmullius, Christiane},
doi = {10.1111/geb.12125},
issn = {1466822X},
journal = {Global Ecology and Biogeography},
keywords = {Boreal forest,Carbon density map,Carbon monitoring,Forest biomass,Forest carbon stocks,Global carbon cycle,Growing stock volume,SAR remote sensing,Temperate forest},
number = {3},
pages = {297--310},
title = {{Carbon stock and density of northern boreal and temperate forests}},
volume = {23},
year = {2014}
}
@article{Urbazaev2015,
abstract = {Woody vegetation cover affects several ecosystem processes including carbon and water cycling, energy fluxes, and fire regimes. In order to understand the dynamics of savanna ecosystems, information on the spatial distribution of woody vegetation over large areas is needed. In this study we sought to assess multi-temporal ALOS PALSAR L-band backscatter to map woody cover in southern African savannas. The SAR data were acquired from the JAXA archive, covering various modes and seasons between 2007 and 2010. We used high resolution airborne LiDAR data as reference data to interpret SAR parameters (including backscatter intensities and polarimetric decomposition components), to develop SAR-based models as well as to validate SAR-based woody cover maps. The LiDAR survey was carried out in April 2008 with the Carnegie Airborne Observatory (CAO, http://cao.ciw.edu). The highest correlations to the reference data were obtained from SAR backscatters of the dry season, followed by the wet season, and the end of the wet season. The volume components from polarimetric decompositions (Freeman-Durden, Van Zyl) were calculated for the end of wet season, and showed similar correlations to the LiDAR data, when compared to cross-polarized backscatters (HV). We observed increased correlation between the SAR and LiDAR datasets with an increase in the spatial scale at which datasets were integrated, with an optimum value at 50m. We modeled woody cover using three scenarios: (1) a single date scenario (i.e., woody cover map based on a single SAR image), (2) a multi-seasonal scenario (i.e., woody cover map based on SAR images from the same year and different seasons, based on key phonological difference), and (3) a multi-annual scenario (i.e., woody cover map based on SAR data from different years). Predicted SAR-based woody cover map based on Fine Beam Dual Polarization dry season SAR backscatters of all years yielded the best performance with an R{\textless}sup{\textgreater}2{\textless}/sup{\textgreater} of 0.71 and RMSE of 7.88{\%}. However, single dry season SAR backscatter achieved only a slightly lower accuracy (R{\textless}sup{\textgreater}2{\textless}/sup{\textgreater}=0.66, RMSE=8.45{\%}) as multi-annual SAR data, suggesting that a single SAR scene from the dry season can also be used for woody cover mapping. Moreover, we investigated the impact of the number of samples on the model prediction performance and showed the benefits of a larger spatially explicit LiDAR dataset compared to much smaller number of samples as they can be collected in the field. Collectively, our results demonstrate that L-band backscatter shows promising sensitivity for the purposes of mapping woody cover in southern African savannas, particularly during the dry season leaf-off conditions.},
author = {Urbazaev, Mikhail and Thiel, Christian and Mathieu, Renaud and Naidoo, Laven and Levick, Shaun R. and Smit, Izak P.J. and Asner, Gregory P. and Schmullius, Christiane},
doi = {10.1016/j.rse.2015.06.013},
issn = {00344257},
journal = {Remote Sensing of Environment},
keywords = {ALOS PALSAR,Backscatter,Carnegie Airborne Observatory,L-band,LiDAR,Savanna,Seasonality,Woody cover},
pages = {138--153},
title = {{Assessment of the mapping of fractional woody cover in southern African savannas using multi-temporal and polarimetric ALOS PALSAR L-band images}},
volume = {166},
year = {2015}
}
@article{o2017synthesis,
abstract = {Forest dieback caused by drought-induced tree mortality has been observed world-wide. Forecasting which trees in which locations are vulnerable to drought-induced mortality is important to predict the consequences of drought on forest structure, biodiversity and ecosystem function. In this paper, our central aim was to compile a synthesis of tree traits and associated abiotic variables that can be used to predict drought-induced mortality. We reviewed the literature that specifically links drought mortality to functional traits and site conditions (i.e. edaphic variables and biotic conditions), targeting studies that show clear use of tree traits in drought analysis. We separated the review into five climatic zones to determine global vs. regionally restricted relationships between traits and mortality. Our synthesis identifies a number of traits that have clear relationships with drought-induced mortality (e.g. wood density at the species level and tree size and growth at the individual level). However, the lack of direct relationships between most traits and drought-induced mortality highlights areas where future research should focus to broaden our understanding. Synthesis and applications. Our synthesis highlights established relationships between traits and drought-induced mortality, presents knowledge gaps for future research focus and suggests monitoring and research avenues for improving our understanding of drought-induced mortality. It is intended to assist ecologists and natural resource managers choose appropriate and measurable parameters for predicting local and regional scale tree mortality risk in different climatic zones within constraints of time and funding availability.},
author = {O'Brien, Michael J. and Engelbrecht, Bettina M.J. and Joswig, Julia and Pereyra, Gabriela and Schuldt, Bernhard and Jansen, Steven and Kattge, Jens and Landh{\"{a}}usser, Simon M. and Levick, Shaun R. and Preisler, Yakir and V{\"{a}}{\"{a}}n{\"{a}}nen, P{\"{a}}ivi and Macinnis-Ng, Cate},
doi = {10.1111/1365-2664.12874},
issn = {13652664},
journal = {Journal of Applied Ecology},
keywords = {climate change,drought-induced mortality,forest dieback,forested climatic zones,plant functional traits,plant–climate interactions,research gaps,water deficit},
number = {6},
pages = {1669--1686},
title = {{A synthesis of tree functional traits related to drought-induced mortality in forests across climatic zones}},
volume = {54},
year = {2017}
}
@article{villamor2011greendale,
author = {{Villamor, P.; Barrell, D.; Litchfield, N.; Van Dissen}, R.; Hornblow and {S. and Levick}, S.},
journal = {GNS Science Consultancy Report},
pages = {1--54},
title = {{Greendale Fault investigation of surface rupture characteristics for fault avoidance zonation, GNS Science Consultancy Report 2011-121}},
url = {http://ecan.govt.nz/publications/Reports/fault-final-report-greendale.pdf},
volume = {121},
year = {2011}
}
@article{Villamor2012,
abstract = {Rupture of the Greendale Fault during the 4 September 2010, M w7.1 Darfield (Canterbury) earthquake produced a zone of ground-surface rupture that severely damaged several houses, buildings and lifelines. Immediately after the earthquake, surface rupture features were mapped in the field and from digital terrain models developed from airborne Light Detection and Ranging (lidar) data. To enable rebuild decisions to be made and for future land use planning, a fault avoidance zone was defined for the Greendale Fault following the Ministry for the Environment guidelines on 'Planning for the Development of Land on or Close to Active Faults'. We present here the most detailed map to date of the fault trace and describe how this was used to define and characterise the fault avoidance zone for land use planning purposes. {\textcopyright} 2012 The Royal Society of New Zealand.},
author = {Villamor, P. and Litchfield, N. and Barrell, D. and {Van Dissen}, R. and Hornblow, S. and Quigley, M. and Levick, S. and Ries, W. and Duffy, B. and Begg, J. and Townsend, D. and Stahl, T. and Bilderback, E. and Noble, D. and Furlong, K. and Grant, H.},
doi = {10.1080/00288306.2012.680473},
issn = {00288306},
journal = {New Zealand Journal of Geology and Geophysics},
keywords = {Active Fault,Canterbury earthquake sequence,Darfield earthquake,Fault avoidance zone,Land use planning,Strike-slip fault,Surface fault rupture map},
number = {3},
pages = {223--230},
title = {{Map of the 2010 Greendale Fault surface rupture, Canterbury, New Zealand: Application to land use planning}},
volume = {55},
year = {2012}
}

repository: geospatialeco/SpatialDataScience

repo_name: geospatialeco/SpatialDataScience


text:
SUMMARY = "Free and Open On-Chip Debugging, In-System Programming and Boundary-Scan Testing"
LICENSE = "GPL-2.0-only"
LIC_FILES_CHKSUM = "file://COPYING;md5=599d2d1ee7fc84c0467b3d19801db870"
DEPENDS = "libusb-compat libftdi"
RDEPENDS:${PN} = "libusb1"

SRC_URI = " \
    git://repo.or.cz/openocd.git;protocol=http;name=openocd;branch=master \
    git://repo.or.cz/r/git2cl.git;protocol=http;destsuffix=tools/git2cl;name=git2cl;branch=master \
    git://github.com/msteveb/jimtcl.git;protocol=http;destsuffix=git/jimtcl;name=jimtcl;branch=master \
    git://repo.or.cz/r/libjaylink.git;protocol=http;destsuffix=git/src/jtag/drivers/libjaylink;name=libjaylink;branch=master \
"

SRCREV_FORMAT = "openocd"
SRCREV_openocd = "91bd4313444c5a949ce49d88ab487608df7d6c37"
SRCREV_git2cl = "8373c9f74993e218a08819cbcdbab3f3564bbeba"
SRCREV_jimtcl = "fcbb4499a6b46ef69e7a95da53e30796e20817f0"
SRCREV_libjaylink = "9aa7a5957c07bb6e862fc1a6d3153d109c7407e4"

PV = "0.12+gitr${SRCPV}"
S = "${WORKDIR}/git"

inherit pkgconfig autotools-brokensep gettext

BBCLASSEXTEND += "native nativesdk"

EXTRA_OECONF = "--enable-ftdi --enable-jtag_vpi --enable-buspirate --disable-doxygen-html --disable-werror"

do_configure() {
    ./bootstrap nosubmodule
    install -m 0755 ${STAGING_DATADIR_NATIVE}/gnu-config/config.guess ${S}/jimtcl/autosetup
    install -m 0755 ${STAGING_DATADIR_NATIVE}/gnu-config/config.sub ${S}/jimtcl/autosetup
    oe_runconf ${EXTRA_OECONF}
}

do_install() {
    oe_runmake DESTDIR=${D} install
    if [ -e "${D}${infodir}" ]; then
      rm -Rf ${D}${infodir}
    fi
    if [ -e "${D}${mandir}" ]; then
      rm -Rf ${D}${mandir}
    fi
    if [ -e "${D}${bindir}/.debug" ]; then
      rm -Rf ${D}${bindir}/.debug
    fi
}

FILES:${PN} = " \
  ${datadir}/openocd/* \
  ${bindir}/openocd \
  "

PACKAGECONFIG[sysfsgpio] = "--enable-sysfsgpio,--disable-sysfsgpio"
PACKAGECONFIG[remote-bitbang] = "--enable-remote-bitbang,--disable-remote-bitbang"
PACKAGECONFIG ??= "sysfsgpio remote-bitbang"

# Can't be built with ccache
CCACHE_DISABLE = "1"

license: MIT

repository: openembedded/meta-openembedded

license_type: permissive

repo_name: openembedded/meta-openembedded

branch_name: refs/heads/master

gha_license_id: MIT

gha_language: BitBake

extension: bb


text:
LICENSE = "GPLv2"
HOMEPAGE = "http://www.gpleda.org/"
FILES_${PN} += "${datadir}/gEDA"
PR = "r1"

DEPENDS = "gtk+ libgeda"

SRC_URI = "http://geda.seul.org/release/v1.4/${PV}/${P}.tar.gz"

inherit autotools pkgconfig

SRC_URI[md5sum] = "e93f0c9747a66ce229702418b49e128f"
SRC_URI[sha256sum] = "97c2dec953e21bfa2633077d084fc0b9aff0c79030f96680ebdef9f97e294cc7"

repository: overo/overo-oe-natty

repo_name: overo/overo-oe-natty

branch_name: HEAD


text:
inherit esw_examples features_check

REQUIRED_MACHINE_FEATURES = "mbox"

ESW_COMPONENT_SRC = "/XilinxProcessorIPLib/drivers/mbox/examples/"

repository: Xilinx/meta-xilinx

repo_name: Xilinx/meta-xilinx

gha_language: C


text:
require ${PN}.inc

SRC_URI = "http://sources.openembedded.org/opie-1.2.5-split_core_settings_light-and-power.tar.bz2;name=split_core_settings_light-and-power \
           http://sources.openembedded.org/opie-1.2.5-split_pics.tar.bz2;name=split_pics \
           http://sources.openembedded.org/opie-1.2.5-split_apps.tar.bz2;name=split_apps"
SRC_URI[split_core_settings_light-and-power.md5sum] = "015b4d171bf91894d8b1fa6679979eee"
SRC_URI[split_core_settings_light-and-power.sha256sum] = "d493018c5b5db81c29585965371402f2d1def7cd7fdcd0bd7a9ccac6ac68d373"
SRC_URI[split_pics.md5sum] = "e9b68749d67295f7080a23e39b17335e"
SRC_URI[split_pics.sha256sum] = "0a7aab6d0bce04d6a9c257d768d8a1a481d38ba527d6e6e50723973789954b4a"
SRC_URI[split_apps.md5sum] = "c765d13427e4dc8ee396e4dfed2dbe73"
SRC_URI[split_apps.sha256sum] = "0fea454d8d286f7febc7449e4a06f73e941e8b22e9bab904a32e57f35479862a"