Effects of litter biomass and soil stoichiometry on leaf litter amphibian and reptile density, biomass, and community structure in tropical wet forests

Authors

Alondra Medina Charriez, James Madison UniversityFollow

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.

Date of Graduation

5-11-2023

Semester of Graduation

Spring

Degree Name

Master of Science (MS)

Department

Department of Biology

Second Advisor

Heather P. Griscom

Third Advisor

Karen Barnard Kubow

Abstract

Understanding the mechanisms behind patterns of diversity and abundance is a major goal of ecology. Research on nutrient stoichiometry has revolutionized the way ecologists understand the patchy distribution of mega-diverse invertebrate taxa that live at the soil surface and leaf litter in tropical wet forests. In this study, I studied the importance of soil nutrient concentrations and stoichiometry, habitat structure, and invertebrate biomass for patterns of amphibian and reptile density, biomass and community structure in two lowland wet tropical forests. I used data from study sites in Los Amigos Biological Station in Peru and two sampling occasions at La Selva Biological Station in Costa Rica. I used standardized leaf litter surveys to measure amphibian and reptile abundance and biomass. I also measured leaf litter mass and depth, invertebrate biomass, soil nutrients and soil stoichiometry. I found that relatively nutrient-rich (Floodplain forests in Peru and Alluvial soils in Costa Rica) and relatively nutrient-poor (Terra Firme forests in Peru and Residual soils in Costa Rica) soils significantly differed in community assemblage of amphibians and reptiles in Peru (R = 0.250, p = 0.001) and Costa Rica in 2010 (R = 0.057, p = 0.004), but not Costa Rica in 2022 (R = 0.018, p = 0.138). A principal components analysis showed that soil nutrient variability across all sites was explained by soil P, C:P, Ca and pH. Structural equation modeling showed that soil P positively influences amphibian and reptile density in Peru and leaf litter mass and invertebrate biomass in Costa Rica. The results of my study helped elucidate the role of soil nutrients and stoichiometry and how bottom-up effects triggered by the availability of nutrients can directly or indirectly influence community composition of higher-level consumers in tropical leaf litter.