My current research focuses on the search for general theory that predicts patterns in species distributions and the application of this theory to the practice of conservation biology. I also have a recent interest in the conservation and ecology of North American bats and a long-standing background in “footprint” accounting.
Universal Patterns in Species Distribution and Abundance
Ecology has been defined as the study of the distribution and abundance of organisms, and the interactions that determine these (Krebs 1972). Much effort has been devoted to determining which of the many hundreds or thousands of possible mechanisms (abiotic, intraspecific, interspecific, evolutionary, etc.) are most important in determining patterns of diversity for a particular species, at a particular spatial or temporal scale.
Despite the enormous variety of organisms, ecosystems, and possible interactions, some striking universality in patterns of distribution and abundance emerge repeatedly. For example, species-area relationships are approximately power laws, species-abundance distributions are often approximately logseries or lognormal, patterns of distance decay are monotonically decreasing, and dispersal distributions often have fat tails.
I am very interested in determining the conditions under which these “universal” patterns arise and exploring what sets of mechanisms, that are common across species and ecosystems, could explain their prevalence. If better characterized, these patterns could represent effective null models for exploring the importance of individual ecological processes (Fox 2011) and form the basis for the broad scale practice of conservation.
I am currently exploring several projects, including:
- Examining scale-collapse behavior in the degree of spatial aggregation exhibited by species of different abundances at different spatial scales
- Developing a general framework for constructing simulated landscapes that reflect any arbitrary pattern of spatial aggregation across scales
- Connecting major macroecological patterns to simple stochastic process models reflecting birth, death, immigration, and emigration
- Leading an effort to develop an open-source Python package called ‘macroeco’ that will enable rapid testing of spatial ecological theory against data
Allometry-Based Metapopulation Models for Reserve Network Design
Perhaps one of the best established examples of universality in ecology is the prevalence of allometric scaling relationships that relate an organism’s body size to various life history characteristics, such as maximum reproductive rate, population density, dispersal distance, and many others. These empirical relationships allow for a specific form of universality – within a defined taxonomic group (such as terrestrial mammals), life history traits are not free to vary independently, but rather come in “packages” (for example, large body size, slow reproduction, low population density, and large dispersal distances).
As part of my dissertation research, I took advantage of these allometric patterns to examine differences in optimal reserve network designs for generic mammals of different body sizes. This analysis found that in patchy landscapes where species exhibit metapopulation dynamics, the relationship between a species’ maximum dispersal distance and the scale of inter-patch distances determines which species may have lower extinction risk in a clustered reserve network (versus a network consisting simply of the largest available patches).
As an additional extension of this approach, I have begun work to apply these allometric metapopulation models to the problem of selecting the most important corridors to maintain between patches in an existing network of protected areas.
Conservation of North American bats
As part of my dissertation research, I conducted several field projects related to the ecology and conservation of California bat communities.
In the summers of 2010 and 2011, I conducted the first community-wide surveys of road avoidance behavior in North American bats, finding that bats, like most terrestrial mammals and birds, show reduced activity levels in roadside habitat. I have also conducted surveys of bat populations in vineyards in Napa and Sonoma county, examining what local and landscape features determine patterns of bat foraging in these agricultural landscapes.
Although the responsibility for environmental impacts is often assigned to the individual or entity who directly causes those impacts (such as a logging company operating in Brazil), the practice of “footprint” accounting instead attempts to allocate responsibility for these impacts to the upstream consumers (such as individuals purchasing wood furniture in the United States) who, through their economic behavior, ultimately drive the downstream impact.
As part of my dissertation, I led an interdisciplinary team in creating the first “wildlife footprint”, an analysis that allocates responsibility for the loss of global bird and mammal populations to the upstream consumers who cause these losses.
In addition to this work, I have recently contributed to a Nitrogen Footprint analysis and online calculator with a group based at the University of Virginia. I have also been active for many years in Ecological Footprint accounting – as the former Manager of the Research and Standards Department at Global Footprint Network, I developed the calculation system behind the National Footprint Accounts, a dataset featured prominently by the World Wide Fund for Nature and used by hundreds of organizations worldwide.