Variation in soil nutrients shape tropical dry forest structure, function, and recovery
Abstract
Tropical dry forests (TDF) are complex, functionally diverse ecosystems that exist across a wide range of environmental gradients. TDFs are also threatened by extensive land-use change and often exist as recovering secondary forests. This combination of environmental stressors imposed by climate and land use change disturbances results in a high potential for multiple resource constraints on forest growth, including water, nitrogen (N), and phosphorus (P) limitation. Here we ask: How do resource constraints impact TDF ecosystem structure, function, composition, and successional recovery?
We use a version of the Ecosystem Demography (ED2) model that is parameterized for TDFs and incorporates multiple resource constraints (carbon, N, P, and water). We simulate eighteen 0.1-hectare inventory plots in Guanacaste, Costa Rica. These plots span a large nutrient gradient and vary greatly in vegetation composition. After running a 10-year baseline simulation initialized with observed stand structure, soil properties, and meteorology, we then ran "swap" simulations where we swapped one component while keeping the other components the same, such as swapping the soil nutrients of the nutrient rich and poor sites. We also simulated increased drought conditions and are expanding our modeling analyses to a broader climatic and geographic range with TDFs sites in Yucatan, Mexico. Across our nutrient gradient of Costa Rican sites, we found plots with higher soil nitrogen and phosphorous showed greater biomass accumulation in the baseline simulations. Nitrogen in particular was important to forest recovery, affecting biomass accumulation and ecosystem functioning such as litter recycling. Although the coefficient of variation in soil phosphorous was three times the coefficient of variation of soil N, the impact of P on biomass was smaller but it shaped the demographic structure. Our Costa Rican "swap" simulations indicated that the nutrient context was more important in explaining site differences in biomass accumulation than either site meteorology or initial vegetation. We also found decreased biomass accumulation with increasing drought. Our results demonstrate a strong link between soil nutrients and TDF structure and function and have important implications for recovering TDFs in an era of changing climate.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B52C..03T
- Keywords:
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- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCESDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCESDE: 0468 Natural hazards;
- BIOGEOSCIENCES