Applicability of functional groups as indicators of resilience and redundancy in the San Pedro Watershed, Arizona

Abstract

Resilience and redundancy are important for long-term conservation since both can indicate the condition and integrity of ecosystems. The goal of this research was to define, develop and demonstrate methods to measure resilience and redundancy in a spatially explicit manner in the San Pedro Watershed, Arizona. Species were categorized to one of several functional groups based on body mass and diet. We calculated metrics of resilience and redundancy for each functional group. Functional groups with smaller-bodied animals had more species than groups with larger-bodied animals suggesting increased resiliency and redundancy for those small-bodied groups. Small-bodied groups were the only body mass groups to include species representing all diet categories (i.e., carnivores, herbivores, omnivores, insectivores, granivores, nectarivores, and piscivores). The insectivore functional group was highly redundant; 154 of 283 (54%) bird species and 23 of 85 (27%) mammal species were insectivores. Carnivorous bird species (37 of 283; 13%) and omnivorous mammal species (23 of 85; 27%) also showed high redundancy relative to other dietary functional groups. Spatial analysis identified the northern portion of the watershed with low mean redundancy for most functional groups across both birds and mammals. Results highlight the importance of large carnivores and small mammals within ecosystems. Results also highlight current ecosystem services provided by insectivorous and nectarivorous species in the American Southwest. This process can be used to measure resilience and redundancy in a spatially explicit manner providing managers information for conservation in the face of climate change when using limited dollars to plan for future changes.

Keywords

• functional groups| resilience| redundancy| conservation| vertebrates| San Pedro Watershed