Arthur R. Marshall, Jr., Ecological Sciences Laboratory

   My core personal research focuses on theoretical and conceptual issues at the population and community levels of ecological organization, and on the task of linking ecology with evolutionary biology. In addition to basic research, I am interested in bringing modern ecological theory to bear on significant applied problems, particularly in conservation biology. I have also carried out large-scale experiments on habitat fragmentation. My students include both theoreticians and empirical, experimental ecologists. I have historically collaborated with many faculty at a wide range of institutions, both inside and outside the USA. Web page with links to publications and research interests.

    My background and interests are at the intersection of statistical methodology and environmental and ecological research. My current interests include development and application of statistical methods for spatial modeling of community structure and species abundances; accounting for uncertainty and sampling error in models of population dynamics; analyses when data are zero-inflated; developing sampling designs and estimators for rare and elusive species; linear and non-linear mixed models; hierarchical modeling; and sampling strategies for spatial data analysis. I collaborate and consult with scientists across many disciplines, including agriculture and natural resources, zoology, ecology, human nutrition, fisheries, and wildlife conservation. Curriculum vitae.

 I have spent my career on Chesapeake Bay creating quantitative methods to analyze networks of trophic transfers. I have developed methods that quantify indirect effects, trophic hierarchies, domains of recycling and whole system indexes of ecosystem organization and flexibility. In the process, I have reached the conclusion that the dynamics of ecosystems are hardly mechanical, but rather dual and dialectic-like. Consequently, I have proposed a perspective on nature that is predicated on processes rather than on objects and laws. My current interest is in promulgating the necessity of indeterminacy for ecosystem sustainability. In economic terms, the implication is that parallel, alternative currencies are likely required to impart sustainability to local and national economies. More than anyone ever wanted to know about me can be found at http://www.cbl.umces.edu/~ulan.

    I have worked at the Ecological Sciences Laboratory doing research on theoretical population biology since 2001. Publications are available through the link below, and include research on adaptation in source-sink systems (Holt et al. 2003, 2004a, 2004b, 2005; Holt and Barfield 2008, 2009b), infectious disease ecology (Orive et al. 2005; Holt and Barfield 2006; Wayne et al. 2011), effects of temporal variation on populations (Holt and Barfield 2003; Holt et al. 2003, 2004b; Roy et al. 2005), evolution (Knight et al. 2008; Barfield et al. 2011), species ranges (Holt et al. in 2011; Holt and Barfield 2011; Filin et al. 2008) and arctic lake ecology (O'Brien et al. 2004, 2005).  Web page with links to publications.

    I am interested in community ecology and more specifically in species niches and the role of resource and habitat availability in generating ecological patterns and processes.  My research investigates habitat use by the community of ungulate herbivores in the Serengeti-Mara, a protected area in East Africa.  The study examines how the habitats used by each species varies seasonally and over time and also investigates if habitat use can be understood from a community perspective by considering species traits such as body size.  I am also interested in the effects of human activity on community and ecosystem functioning, sustainable management of natural resources, and conservation.