LNG 1-6
Effects of soil quality and stand age on acoustically active fauna and terrestrial mammals in a regenerating tropical dry forest system

Tuesday, August 11, 2015: 2:05 PM
311, Baltimore Convention Center
Timothy L. H. Treuer, Ecology and Evolutionary Biology, Princeton University, Princeton, NJ
Justin Becknell, Institute at Brown for Environment & Society, Brown University, Providence, RI
Andrew P. Dobson, Ecology & Evolutionary Biology, Princeton University, Princeton, NJ
Jennifer S. Powers, Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN
David S. Wilcove, Ecology and Evolutionary Biology, Princeton University, Princeton, NJ

Large-scale ecological restoration has been shown to be a powerful method of preserving biodiversity in highly fragmented tropical dry forest landscapes, with perhaps no example more striking than the Área de Conservación Guanacaste (ACG) in Costa Rica and its 40,000+ ha of former cattle pasture in various states of recovery to mature dry forest.  However, understanding the optimal allocation of conservation resources to habitat restoration in Mesoamerican dry forest requires a more nuanced understanding of the drivers of community composition in regenerating habitat than currently exists for the ACG or elsewhere.  Among the factors that have been identified as modulating floral composition of regenerating tropical forest (including the ACG) is edaphic variation.  We investigated how edaphic variation interacts with stand age to affect the structure and composition of three faunal assemblages by surveying two chronosequences of forest plots on nutrient-poor and nutrient-rich soils in the ACG.  We asked the following specific questions: (1) Do bird, bat, and terrestrial mammal assemblages diverge in composition between regenerating forest on nutrient-rich and poor soils, and if so is the divergence greater in younger or older forest stands? (2) Do abundance and diversity of these assemblages increase with stand age?


Plots were surveyed with passive acoustic recorders (SongMeter 2), two ultrasonic recording units (Pettersson D500 and SongMeter 3), and infrared flash motion-triggered camera traps (Bushnell HD Hybrid Trail Cam) between June and August 2014 and January and February 2015.  Over 5,000 hours of audio were recorded and 2,000 animal images captured over 1000 trap*days.  Ordination techniques and clustering analysis revealed significant differences in community composition in all three assemblages (bat identifications were made at the level of ‘sono-species’ based on echolocation call morphologies) between soil types, with older growth plots less dissimilar than younger, however less than 50% of the variation in species composition were explained by the first two principal components, and species accumulation curves and numerous singletons for both individual plots and for each soil type indicate sampling saturation has not been achieved for any faunal group.  Species richness (observed and Chao-estimated) and Shannon-indices of all three assemblages was significantly higher in plots on nutrient rich soil, and a positive correlation was found between both measures of diversity and stand age for birds and bats, but not terrestrial mammals.  This study highlights the potential of acoustic survey methods for rapid and non-invasive for biodiversity appraisal.