@article{BuchmannSchurrNathanetal.2011, author = {Buchmann, Carsten M. and Schurr, Frank Martin and Nathan, Ran and Jeltsch, Florian}, title = {An allometric model of home range formation explains the structuring of animal communities exploiting heterogeneous resources}, series = {Oikos}, volume = {120}, journal = {Oikos}, number = {1}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0030-1299}, doi = {10.1111/j.1600-0706.2010.18556.x}, pages = {106 -- 118}, year = {2011}, abstract = {Understanding and predicting the composition and spatial structure of communities is a central challenge in ecology. An important structural property of animal communities is the distribution of individual home ranges. Home range formation is controlled by resource heterogeneity, the physiology and behaviour of individual animals, and their intra- and interspecific interactions. However, a quantitative mechanistic understanding of how home range formation influences community composition is still lacking. To explore the link between home range formation and community composition in heterogeneous landscapes we combine allometric relationships for physiological properties with an algorithm that selects optimal home ranges given locomotion costs, resource depletion and competition in a spatially-explicit individual-based modelling framework. From a spatial distribution of resources and an input distribution of animal body mass, our model predicts the size and location of individual home ranges as well as the individual size distribution (ISD) in an animal community. For a broad range of body mass input distributions, including empirical body mass distributions of North American and Australian mammals, our model predictions agree with independent data on the body mass scaling of home range size and individual abundance in terrestrial mammals. Model predictions are also robust against variation in habitat productivity and landscape heterogeneity. The combination of allometric relationships for locomotion costs and resource needs with resource competition in an optimal foraging framework enables us to scale from individual properties to the structure of animal communities in heterogeneous landscapes. The proposed spatially-explicit modelling concept not only allows for detailed investigation of landscape effects on animal communities, but also provides novel insights into the mechanisms by which resource competition in space shapes animal communities.}, language = {en} } @article{BuchmannSchurrNathanetal.2012, author = {Buchmann, Carsten M. and Schurr, Frank Martin and Nathan, Ran and Jeltsch, Florian}, title = {Movement upscaled - the importance of individual foraging movement for community response to habitat loss}, series = {Ecography : pattern and diversity in ecology ; research papers forum}, volume = {35}, journal = {Ecography : pattern and diversity in ecology ; research papers forum}, number = {5}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0906-7590}, doi = {10.1111/j.1600-0587.2011.06924.x}, pages = {436 -- 445}, year = {2012}, abstract = {Habitat loss poses a severe threat to biodiversity. While many studies yield valuable information on how specific species cope with such environmental modification, the mechanistic understanding of how interacting species or whole communities are affected by habitat loss is still poor. Individual movement plays a crucial role for the space use characteristics of species, since it determines how individuals perceive and use their heterogeneous environment. At the community level, it is therefore essential to include individual movement and how it is influenced by resource sharing into the investigation of consequences of habitat loss. To elucidate the effects of foraging movement on communities in face of habitat loss, we here apply a recently published spatially-explicit and individual-based model of home range formation. This approach allows predicting the individual size distribution (ISD) of mammal communities in simulation landscapes that vary in the amount of suitable habitat. We apply three fundamentally different foraging movement approaches (central place forager (CPF), patrolling forager (PF) and body mass dependent nomadic forager (BNF)). Results show that the efficiency of the different foraging strategies depends on body mass, which again affects community structure in face of habitat loss. CPF is only efficient for small animals, and therefore yields steep ISD exponents on which habitat loss has little effect (due to a movement limitation of body mass). PF and particularly BNF are more efficient for larger animals, resulting in less steep ISDs with higher mass maxima, both showing a threshold behaviour with regard to loss of suitable habitat. These findings represent a new way of explaining observed extinction thresholds, and therefore indicate the importance of individual space use characterized by physiology and behaviour, i.e. foraging movement, for communities and their response to habitat loss. Findings also indicate the necessity to incorporate the crucial role of movement into future conservation efforts of terrestrial communities.}, 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} }