@article{KathBoitGuilletal.2018,
  author    = {Kath, Nadja J. and Boit, Alice and Guill, Christian and Gaedke, Ursula},
  title     = {Accounting for activity respiration results in realistic trophic transfer efficiencies in allometric trophic network (ATN) models},
  series = {Theoretical ecology},
  volume    = {11},
  journal   = {Theoretical ecology},
  number    = {4},
  publisher = {Springer},
  address   = {Heidelberg},
  issn      = {1874-1738},
  doi       = {10.1007/s12080-018-0378-z},
  pages     = {453 -- 463},
  year      = {2018},
  abstract  = {Allometric trophic network (ATN) models offer high flexibility and scalability while minimizing the number of parameters and have been successfully applied to investigate complex food web dynamics and their influence on food web diversity and stability. However, the realism of ATN model energetics has never been assessed in detail, despite their critical influence on dynamic biomass and production patterns. Here, we compare the energetics of the currently established original ATN model, considering only biomass-dependent basal respiration, to an extended ATN model version, considering both basal and assimilation-dependent activity respiration. The latter is crucial in particular for unicellular and invertebrate organisms which dominate the metabolism of pelagic and soil food webs. Based on metabolic scaling laws, we show that the extended ATN version reflects the energy transfer through a chain of four trophic levels of unicellular and invertebrate organisms more realistically than the original ATN version. Depending on the strength of top-down control, the original ATN model yields trophic transfer efficiencies up to 71\% at either the third or the fourth trophic level, which considerably exceeds any realistic values. In contrast, the extended ATN version yields realistic trophic transfer efficiencies 30\% at all trophic levels, in accordance with both physiological considerations and empirical evidence from pelagic systems. Our results imply that accounting for activity respiration is essential for consistently implementing the metabolic theory of ecology in ATN models and for improving their quantitative predictions, which makes them more powerful tools for investigating the dynamics of complex natural communities.},
  language  = {en}
}
@article{AlonzoBookhagenMcFaddenetal.2015,
  author    = {Alonzo, Michael and Bookhagen, Bodo and McFadden, Joseph P. and Sun, Alex and Roberts, Dar A.},
  title     = {Mapping urban forest leaf area index with airborne lidar using penetration metrics and allometry},
  series = {Remote sensing of environment : an interdisciplinary journal},
  volume    = {162},
  journal   = {Remote sensing of environment : an interdisciplinary journal},
  publisher = {Elsevier},
  address   = {New York},
  issn      = {0034-4257},
  doi       = {10.1016/j.rse.2015.02.025},
  pages     = {141 -- 153},
  year      = {2015},
  abstract  = {In urban areas, leaf area index (LAI) is a key ecosystem structural attribute with implications for energy and water balance, gas exchange, and anthropogenic energy use. In this study, we estimated LAI spatially using airborne lidar in downtown Santa Barbara, California, USA. We implemented two different modeling approaches. First, we directly estimated effective LAI (LAIe) using scan angle- and clump-corrected lidar laser penetration metrics (LPM). Second, we adapted existing allometric equations to estimate crown structural metrics including tree height and crown base height using lidar. The latter approach allowed for LAI estimates at the individual tree-crown scale. The LPM method, at both high and decimated point densities, resulted in good linear agreement with estimates from ground-based hemispherical photography (r(2) = 0.82, y = 0.99x) using a model that assumed a spherical leaf angle distribution. Within individual tree crown segments, the lidar estimates of crown structure closely paralleled field measurements (e.g., r(2) = 0.87 for crown length). LAI estimates based on the lidar crown measurements corresponded well with estimates from field measurements (r(2) = 0.84, y = 0.97x + 0.10). Consistency of the LPM and allometric lidar methods was also strong at 71 validation plots (r(2) = 0.88) and at 450 additional sample locations across the entire study area (r(2) = 0.72). This level of correspondence exceeded that of the canopy hemispherical photography and allometric, ground-based estimates (r(2) = 0.53). The first-order alignment of these two disparate methods may indicate that the error bounds for mapping LAI in cities are small enough to pursue large scale, spatially explicit estimation. (C) 2015 Elsevier Inc All rights reserved.},
  language  = {en}
}
@article{BinzerBroseCurtsdotteretal.2011,
  author    = {Binzer, Amrei and Brose, Ulrich and Curtsdotter, Alva and Ekloef, Anna and Rall, Bjoern C. and Riede, Jens O. and de Castro, Francisco},
  title     = {The susceptibility of species to extinctions in model communities},
  series = {Basic and applied ecology : Journal of the Gesellschaft f{\"u}r {\"O}kologie},
  volume    = {12},
  journal   = {Basic and applied ecology : Journal of the Gesellschaft f{\"u}r {\"O}kologie},
  number    = {7},
  publisher = {Elsevier},
  address   = {Jena},
  issn      = {1439-1791},
  doi       = {10.1016/j.baae.2011.09.002},
  pages     = {590 -- 599},
  year      = {2011},
  abstract  = {Despite the fact that the loss of a species from a community has the potential to cause a dramatic decline in biodiversity, for example through cascades of secondary extinctions, little is known about the factors contributing to the extinction risk of any particular species. Here we expand earlier modeling approaches using a dynamic food-web model that accounts for bottom-up as well as top-down effects. We investigate what factors influence a species' extinction risk and time to extinction of the non-persistent species. We identified three basic properties that affect a species' risk of extinction. The highest extinction risk is born by species with (1) low energy input (e.g. high trophic level), (2) susceptibility to the loss of energy pathways (e.g. specialists with few prey species) and (3) dynamic instability (e.g. low Hill exponent and reliance on homogeneous energy channels when feeding on similarly sized prey). Interestingly, and different from field studies, we found that the trophic level and not the body mass of a species influences its extinction risk. On the other hand, body mass is the single most important factor determining the time to extinction of a species, resulting in small species dying first. This suggests that in the field the trophic level might have more influence on the extinction risk than presently recognized.},
  language  = {en}
}
@article{BuchmannSchurrNathanetal.2013,
  author    = {Buchmann, Carsten M. and Schurr, Frank Martin and Nathan, Ran and Jeltsch, Florian},
  title     = {Habitat loss and fragmentation affecting mammal and bird communities-The role of interspecific competition and individual space use},
  series = {Ecological informatics : an international journal on ecoinformatics and computational ecolog},
  volume    = {14},
  journal   = {Ecological informatics : an international journal on ecoinformatics and computational ecolog},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1574-9541},
  doi       = {10.1016/j.ecoinf.2012.11.015},
  pages     = {90 -- 98},
  year      = {2013},
  abstract  = {Fragmentation and loss of habitat are major threats to animal communities and are therefore important to conservation. Due to the complexity of the interplay of spatial effects and community processes, our mechanistic understanding of how communities respond to such landscape changes is still poor. Modelling studies have mostly focused on elucidating the principles of community response to fragmentation and habitat loss at relatively large spatial and temporal scales relevant to metacommunity dynamics. Yet, it has been shown that also small scale processes, like foraging behaviour, space use by individuals and local resource competition are also important factors. However, most studies that consider these smaller scales are designed for single species and are characterized by high model complexity. Hence, they are not easily applicable to ecological communities of interacting individuals. To fill this gap, we apply an allometric model of individual home range formation to investigate the effects of habitat loss and fragmentation on mammal and bird communities, and, in this context, to investigate the role of interspecific competition and individual space use. Results show a similar response of both taxa to habitat loss. Community composition is shifted towards higher frequency of relatively small animals. The exponent and the 95\%-quantile of the individual size distribution (ISD, described as a power law distribution) of the emerging communities show threshold behaviour with decreasing habitat area. Fragmentation per se has a similar and strong effect on mammals, but not on birds. The ISDs of bird communities were insensitive to fragmentation at the small scales considered here. These patterns can be explained by competitive release taking place in interacting animal communities, with the exception of bird's buffering response to fragmentation, presumably by adjusting the size of their home ranges. These results reflect consequences of higher mobility of birds compared to mammals of the same size and the importance of considering competitive interaction, particularly for mammal communities, in response to landscape fragmentation. Our allometric approach enables scaling up from individual physiology and foraging behaviour to terrestrial communities, and disentangling the role of individual space use and interspecific competition in controlling the response of mammal and bird communities to landscape changes.},
  language  = {en}
}