Effects Of Patch Size And Matrix Type On Bird Assemblages Within Central Florida Cypress Domes

The numerous studies on the effects of patch size on bird assemblages have produced varied results. I studied the effects of patch size and surrounding matrix on bird assemblages within central Florida cypress domes. My null hypothesis was that bird assemblages within cypress domes are unaffected by dome size or development in the matrix around the dome. My alternative hypothesis was that differences in bird assemblages are correlated with size and the degree of development within the matrix. I classified a pool of over a thousand domes according to three size categories and four matrix types. Three representatives for each combination of size and matrix were spot mapped for birds from May through August 2005. I examined the relationship of species richness and bird guilds to patch size and surrounding matrix. I also measured a series of potential covariates for each dome to account for variation among the three size-matrix representatives for each combination. Richness and abundance counts were divided by the number of listening points to standardize the data by effort. I found that the standardized species richness of bird assemblages significantly increased with the patch size of cypress domes; however, matrix and the interaction effect of size and matrix on overall standardized species richness were not significant. Significant covariates included percent of the buffer undeveloped, percent herbaceous cover, and the number of listening points per unit area. A linear regression tested for significant effects of log area and matrix on standardized species richness. Matrix was not significant, but log area did have a significant effect on standardized species richness. The MANOVA tests for guild richness data indicated no significant effects of dome size, matrix, or their interaction effect on diet, foraging, or location guilds. There were no significant main or interaction effects on any individual guilds in the ANOVA output. Individual backward linear regressions done on each guild indicated that matrix did not have significant effects on any guild, but log area had significant effects on ground foragers, lower-canopy foragers, omnivores, herbivores, and edge species. I then investigated the effects of size and matrix on standardized guild abundance. Dome size and matrix significantly effected diet guild abundance, but the size-matrix interaction did not. Dome size significantly affected insectivores, omnivores, and carnivores. Matrix had a significant effect on omnivores, herbivores, and carnivores. The size and matrix interaction had a significant effect on carnivores. Dome size and matrix significantly affected foraging guild abundance, but the size-matrix interaction did not. Dome size significantly affected ground, lower- and upper-canopy foragers. Matrix had a significant effect on ground, water, and upper-canopy foragers. The size and matrix interaction was not significant for any foraging guild. Dome size and matrix significantly effected location guild abundance, but the size-matrix interaction did not. Dome size significantly affected edge and interior species. Matrix had a significant effect on edge and interior species. The size and matrix interaction was not significant for any location guild. The relationship between species richness and habitat area is well-documented, and the results of this study were consistent with the expectation of higher species richness in larger areas. If maintaining high species richness is the sole goal of conservationists, then large habitat fragments would be preferable regardless of surrounding matrix. Nevertheless, species richness alone is not informative of the potential effects of patch size and matrix on the composition of an avian assemblage. Guild analysis gives insight into community structure and should be considered in addition to simple measures of species richness. Patch size and matrix type significantly affected a number of guilds, and several factors could contribute to the observed differences in guilds across patch size categories and matrix types. Different habitats are available to birds in domes of each size class and matrix type. The potential for diverse foraging opportunities increases as domes increase in size and change in relation to their surrounding matrix. A more detailed analysis is needed to determine how differences in vegetation of domes and surrounding matrix affect guilds, members of which may use habitats both within domes and the matrix. Cypress domes in the central Florida area face severe alteration or destruction due to rapid development. Long-term research that focuses on domes before and after development is needed to understand how changes in the matrix or size of the domes affect all resident flora and fauna. A variety of taxa and biogeochemical processes should be researched. Domes are naturally highly variable in size, shape, and structure, and development changes all of these characteristics. Conservation biologists and managers urgently need to determine how development affects cypress domes and what can be done to maintain their characteristic biodiversity