I am interested in patterns of biodiversity and mechanisms responsible for those patterns at the population, community and landscape scale.  My career research plans are to investigate the causes and consequences of land use and land management on biodiversity.

Trophic Structure and Community Assembly: mangrove island food-webs

Community Assembly and Trophic Structure to detect mechanisms responsible for complex community structure and effects

Trophic structure patterns, such as constant connectance, are systematically observed in natural systems but lack mechanistic explanations. By examining the role of trophic breadth during community assembly, I found a relationship between colonization success and trophic breadth that helps explain food-web patterns and corroborates assertions that community assembly is influenced by species trophic breadth. By generalizing the idea of sequential dependency (Holt et al. 1999), or the dependency on prey colonizing beforehand, we detected colonization patterns by trophic breadth that influenced food-web structure. (Piechnik, Lawler, Martinez. 2008. Oikos 117: 665-674)

reprint

Sequential Colonization by Trophic Levels and transient effects of habitat size and quality

Species diversity and trophic structure can be influenced by colonist arrival order and by habitat area and productivity. For my dissertation research, I used a field experiment to test for sequential dependency by trophic levels in a aphid food-web module during community assembly in plots manipulated for area and productivity. Specialists demonstrated sequential colonization from lowest to highest trophic level, however, effects of area and productivity on trophic levels were transient across sample dates. Specialists, though more constrained in their prey options, colonized well before the facultative and obligate generalist predators. (Piechnik. 2013. Acta Oecologica 47: 85 - 94) 

reprint

Size and productivity effects on community diversity during a natural colonization experiment.

Food chain length is limited by the amount of energy available within a system, and by the inefficient energy transfer between trophic levels. That is, the amount of energy transferred diminishes at each link in the food chain. But larger habitat areas with greater rates of productivity should provide more foraging area and have more energy, potentially supporting more links in the food chain (Productive Space Hypothesis – Schoener 1989). I examined the community responses of colonists on “terrestrial islands” that were manipulated for area and productivity. Similar to other studies, I found that the influence of area was greater than productivity on community-level properties. Large plots had greater predator-prey ratios, but overall abundance was greater on small plots. (Piechnik 2007. Dissertation. University of California, Davis)

abstract

Land-use and Land Management: placing best management practices to protect streams

Nonpoint source pollution from pastureland and other agriculture land is a major cause of water quality degradation in streams and lakes. Placing Best Management Practices (BMPs) can be improved by applying GIS-based methods that determine the stream bank entry point, the length of flow-path from source to stream, and upslope contributing areas. Our study examined how DEM resolution influenced these hydrologic attributes with the purpose to improve BMP placement by managers and planners. (Piechnik, Goslee, Veith, Bishop, Brooks. 2012. Landscape Ecology 27: 617 - 619)

reprint: Landscape Ecology

reprint: USDA Fact Sheet

Land-use and Land Management

Biodiversity responses and the study of management practices

The Gettysburg National Military Park (GNMP) underwent restoration efforts to restore open vistas of the 1863 battle landscapes by removing wooded areas. A monitoring plan was designed from an ecological analysis of the extensive inventory of park arthropods (>26,000 individuals). Responses to environmental gradients, habitat type, and land use within the GNMP were used to to establish a biodiversity monitoring plan to study species that are at-risk such as trophic and habitat specialists, pollinators, as well as potential pest, invasive, and exotic species.

NPS Summary