COS 10-1
Avian species and functional diversity in agricultural landscapes: landscape heterogeneity matters

Monday, August 11, 2014: 1:30 PM
Regency Blrm E, Hyatt Regency Hotel
Myung-bok Lee, Department of Wildlife, Fisheries, and Aquaculture, Mississippi State University, Mississippi State, MS
James Martin, Department of Wildlife, Fisheries, and Aquaculture, Mississippi State University, Mississippi State, MS

The positive relationship between species diversity and habitat heterogeneity is widely accepted in avian studies. However, the relationship is primarily based on taxonomic diversity (richness or Shannon index). Other facets of diversity such as functional diversity that is interrelated with ecosystem functioning are rarely explored. We investigated the avian diversity-landscape heterogeneity relationship in agricultural landscapes by considering functional diversity, richness, and individual species responses. We also assessed the effects of agricultural fields managed for declining early-successional species (State Acres For wildlife Enhancement, CP38) on avian diversity. We used breeding bird data collected at CP38 fields in Mississippi during 2010-2012. We focused on 4 common functional diversity indices: dendrogram-based functional diversity (FDw), functional evenness (FEve), divergence (FDiv), and dispersion (FDis). We used a Shannon’s landscape diversity index as an indicator of landscape heterogeneity and two principal components (heterogeneity, increasing landscape heterogeneity from agricultural lands to non-agricultural lands and CP38, increasing amount of CP38 fields) as environmental variables. The relationship between diversity indices and those variables was modeled using a simultaneous autoregressive model to account for spatial autocorrelation. We adopted a hierarchical multi-species dynamic occupancy model with an autocovariate to examine species richness and individual species responses to environmental variables.


We found significant positive effects of heterogeneity on FDw and FDiv and negative effects of CP38 on FDvi and FDis, but no effects of either of the variables on FEve. In other words, with increasing landscape heterogeneity, a bird community consisted of more functionally unique species and the most abundant species occur at the edges of the functional trait range. Increasing CP38 led to a bird community composing more functionally similar and abundant species. Richness also showed the similar pattern: the mean estimate of the community-level hyper-parameter for heterogeneity was positive, while the mean estimate of CP38 was negative. At individual species level, only 1 species showed a significantly negative response to heterogeneity. Only 2 species responded positively to CP38 and most species negatively associated with CP38 were non-early successional species. Our results suggest that landscape heterogeneity—landscape diversity of non-agricultural natural habitats—could  be an important factor to promote avian diversity (functional diversity and taxonomic diversity) in agricultural landscapes. Our results also suggest that although CP38 provides some benefits for several species, the effectiveness of CP38 to conserve avian diversity and even declining early-successional species could be limited without the consideration of landscape heterogeneity.