Nutrient Budgets Across Pantropical Environmental and Disturbance Gradients
Barbara Bomfim1* (firstname.lastname@example.org), Bruno Gimenez2, Sarah Camelo3, Luciane Carvalho3, Alicia Monteiro3, Anthony Walker4, Ryan Knox1, Adriano Lima3, Niro Higuchi3, Lara Kueppers1, Yadvinder Malhi5, Jeffrey Chambers1
1Lawrence Berkeley National Laboratory, Berkeley, CA; 2University of California–Berkeley, CA; 3National Institute of Amazonian Research, Manaus, Brazil; 4Oak Ridge National Laboratory, Oak Ridge, TN; 5Oxford University, Oxford, UK
As nutrient resource availability can moderate tropical forest demography, function, and recovery trajectories following disturbances and environmental changes, the carbon, nitrogen, and phosphorous nutrient-enabled FATES model (FATES-CNP) under development by NGEE-Tropics will provide a more accurate representation of nutrient controls on demographic rates and structure, and of carbon and water cycling in tropical forests. FATES-CNP will improve predictions of how primary nutrients (e.g., nitrogen and phosphorus) constrain tropical forest responses to disturbances and environmental changes throughout the 21st century. To predict how nutrient budgets and the relationships between ecosystem nutrient budgets and net primary productivity vary across pantropical environmental and disturbance gradients, researchers integrate observational and experimental plot-level data from forest sites, including those from the Global Ecosystem Monitoring network, at various successional stages spanning nutrient, climate, and disturbance gradients into the calibration and validation of FATES-CNP. Simultaneously considered were changes in carbon and nutrient budgets, disturbance regimes, and plant functional diversity within the surveyed tropical forests. Work is ongoing at the Manaus ZF-2 research station to quantify: (1) carbon and nutrient stocks in the leaf and wood pools of generalist and specialist species and their surrounding soil pools in habitats spanning a soil texture and nutrient gradient; (2) the temporal dynamics of leaf litter production, nutrient retranslocation, and phenology in pioneer and non-pioneer species varying in wood density; and (3) throughfall and precipitation nutrient inputs in forests affected and unaffected by logging. Preliminary results indicate that nutrient generalist and specialist species occur in plateau and valley soils showing a wide range in sand, clay, total carbon and nitrogen, and available phosphorus concentrations. Across all species, wood carbon and nitrogen concentrations varied from 42.4 to 66.7% and 0.16 to 0.51%, respectively. Phosphorus varied from 0.03 to 0.15 g/kg with a two-fold difference in mean wood phosphorus but no difference in mean wood carbon and nitrogen between valley and plateau species. Future work will quantify the relationship between net primary productivity, nutrient uptake, and resorption across nine old growth and logged lowland wet tropical forests in Sabah, Malaysian Borneo. This pantropical data synthesis will elucidate how nutrient use traits relate to plant functional composition and community dynamics across pantropical sites and gradients, emergent signals of disturbances in nutrient budgets, and how nutrient budgets modulate recovery trajectories following disturbances and drought stress.