RUI: Biogeographical Impacts of Recent Bark Beetle Epidemics on Cavity-Nesting Birds in Arizona.

Carthage College, Kenosha WI

Investigators

Abstract

Biogeography unites the spatial approach of geography with the functional approach of ecology, viewing the origins and consequences of spatial patterns on ecological processes. Biogeographers investigate relationships between ecological patterns (spatial and temporal) and processes, such as disturbances and species distributions. This research project will explore the causes and consequences of human activity on relationships between wildlife and their habitat requirements across a range of scales. Specifically, this study will determine effects of recent bark beetle outbreaks on cavity nesting birds in northern Arizona. The objectives of this project are to: (1) describe spatial patterns, density, decay rates, and dynamics of bark beetle-killed snags (standing dead trees) in ponderosa pine forests of the American Southwest; (2) predict the probability of snag use by cavity nesters based on these snag characteristics comparing snags killed in bark beetle outbreaks vs. individual mortality; and (3) develop a database of bark beetle-killed snags to add to our fire-killed snag dynamics model in order to test ecological hypotheses and provide guidelines for forest managers. This research will advance biogeographical theories through modeling bird spatial patterns across a range of disturbance scales, from individual killed snags to landscape-scale mortality. This project will strengthen the research environment at an undergraduate liberal arts college through enhancing the infrastructure of the undergraduate labs and promoting the integration of research and undergraduate education. The study area will include unburned southwestern ponderosa pine forest that recently experienced bark beetle outbreaks paired with unburned areas without bark beetle outbreak. Wildlife data collected will include the number of excavated cavities, the number of natural cavities, evidence of foraging, and direct wildlife observations. Tree data collected will include increment core samples, mapped locations, species, diameter, height, top condition, snag condition, bark cover, cavities, dead limbs, lean, basal area, and decay class. The project will assess spatial structure and patterns and assist in evaluating effects of disturbances on landscapes. In addition, quantifying structural patterns will help to evaluate how these landscapes affect abundance and distribution of birds at present and into the future through habitat modeling. Direct applications of this biogeographic research include forest management decisions such as the number of snags and spatial pattern of the snags to retain in salvage logging and restoration efforts in southwestern ponderosa pine forests. Determining the transition rate from snag to fallen log is important for predicting availability of wildlife habitat. Knowing which trees or snags will remain standing longest and are most used by cavity nesters will provide guidance in determining how many live tree replacements are needed and in developing future snag management plans.