A5058380191- Soil Carbon and Nitrogen Dynamics
- Peatlands and Wetlands Ecology
- Soil and Water Nutrient Dynamics
- Atmospheric and Environmental Gas Dynamics
- Ecology and Vegetation Dynamics Studies
- Microbial Community Ecology and Physiology
- Plant Water Relations and Carbon Dynamics
- Forest ecology and management
- Soil and Unsaturated Flow
- Coastal wetland ecosystem dynamics
- Fire effects on ecosystems
- Rangeland and Wildlife Management
- Soil erosion and sediment transport
- Iron oxide chemistry and applications
- Groundwater and Isotope Geochemistry
- Conservation, Biodiversity, and Resource Management
- Methane Hydrates and Related Phenomena
- Soil Geostatistics and Mapping
- Mine drainage and remediation techniques
- Geology and Paleoclimatology Research
- Plant responses to elevated CO2
- Wastewater Treatment and Nitrogen Removal
- CO2 Sequestration and Geologic Interactions
- Hydrocarbon exploration and reservoir analysis
- Forest Management and Policy
University of California, Berkeley
2016-2025
Berkeley College
2021
Boston University
1999-2020
San Diego State University
2020
Macalester College
2020
University of New Hampshire
2020
Louisiana Department of Natural Resources
2020
Los Alamos National Laboratory
2020
Universität Hamburg
2020
Oak Ridge National Laboratory
2020
Litter decomposition provides the primary source of mineral nitrogen (N) for biological activity in most terrestrial ecosystems. A 10-year experiment 21 sites from seven biomes found that net N release leaf litter is dominantly driven by initial tissue concentration and mass remaining regardless climate, edaphic conditions, or biota. Arid grasslands exposed to high ultraviolet radiation were an exception, where was insensitive N. Roots released linearly with exhibited little immobilization....
Assistant professor in the Department of Biology at Western Washington University, Bellingham, 98225-9160 10: Professor Laboratoire d'Ecologie de Sols Tropicaux, ORSTOM/Universite Paris VI, 32 Avenue Henri Varagnat, 93143 Bondy, France 11: Senior scientist Centre for Terrestrial Ecology, Netherlands Institute 6666 ZG Heteren, Utrecht, 12: Environmental Studies, University 13: Soil Biology, Academy Sciences Czech Republic, Na sadkach 7, 370 05 Ceske Budejovice, Republic 14: Science,...
Abstract Approximately half of the tropical biome is in some stage recovery from past human disturbance, most which secondary forests growing on abandoned agricultural lands and pastures. Reforestation these lands, both natural managed, has been proposed as a means to help offset increasing carbon emissions atmosphere. In this paper we discuss potential serve sinks for atmospheric dioxide aboveground biomass soils. A review literature data shows that increases at rate 6.2 Mg ha − 1 yr during...
Abstract As atmospheric CO 2 increases, ecosystem carbon sequestration will largely depend on how global changes in climate alter the balance between net primary production and decomposition. The response of to climatic change has been examined using well‐validated mechanistic models, but same is not true for decomposition, a source . We used Long‐term Intersite Decomposition Experiment Team (LIDET) dataset model‐selection techniques choose parameterize model that describes patterns litter...
Tropical secondary forests recover quickly (decades) in tree species richness but slowly (centuries) composition.
Microbial communities and their associated enzyme activities affect the amount chemical quality of carbon (C) in soils. Increasing nitrogen (N) deposition, particularly N-rich tropical forests, is likely to change composition behavior microbial feed back on ecosystem structure function. This study presents a novel assessment mechanistic links between responses N deposition shifts soil organic matter (SOM) quantity. We used phospholipid fatty acid (PLFA) analysis assays soils assess community...
Rapidly fluctuating environmental conditions can significantly stress organisms, particularly when fluctuations cross thresholds of normal physiological tolerance. Redox potential are common in humid tropical soils, and microbial community acclimation or avoidance strategies for survival will turn shape diversity biogeochemistry. To assess the extent to which indigenous bacterial archaeal communities adapted changing redox potential, soils were incubated under static anoxic, oxic conditions,...
Abstract Decomposition is a critical process in global carbon cycling. During decomposition, leaf and fine root litter may undergo later, relatively slow phase; past long‐term experiments indicate this phase occurs, but whether it general phenomenon has not been examined. Data from Long‐term Intersite Experiment Team, representing 27 sites nine types (for total of 234 cases) was used to test the frequency decomposition. Litter mass remaining after up 10 years decomposition fit models that...
Abstract Humid tropical forests have the fastest rates of organic matter decomposition globally, which often coincide with fluctuating oxygen ( O 2 ) availability in surface soils. Microbial iron (Fe) reduction generates reduced [Fe(II)] under anaerobic conditions, oxidizes to Fe(III) subsequent aerobic conditions. We demonstrate that Fe (II) oxidation stimulates via two mechanisms: (i) oxidation, likely driven by reactive species; and (ii) increased dissolved carbon (DOC) availability,...
Soil profiles are rarely homogeneous. Resource availability and microbial abundances typically decrease with soil depth, but microbes found in deeper horizons still important components of terrestrial ecosystems. By studying 20 across the United States, we documented consistent changes bacterial archaeal communities depth. Deeper soils harbored distinct from those more commonly studied surface horizons. Most notably, that candidate phylum Dormibacteraeota (formerly AD3) was often dominant...
The internal transformations of nitrogen in terrestrial ecosystems exert strong controls over availability to net primary productivity, nitrate leaching into groundwater, and emissions nitrogen-based greenhouse gas. Here we report a reductive pathway for cycling upland tropical forest soils that decreases the amount susceptible denitrification, thus conserving ecosystem. Using 15N tracers measured rates dissimilatory reduction ammonium (DNRA) humid averaging ∼0.6 μg·g−1·d−1. Rates DNRA were...
Abstract Our research takes advantage of a historical trend in natural reforestation abandoned tropical pastures to examine changes soil carbon (C) during 80 years secondary forest regrowth. We combined chronosequence approach with differences the abundance 13 C between C3 (forest) and C4 (pasture) plants estimate turnover times bulk density fractions. Overall, gains were compensated for by loss residual pasture‐derived C, resulting no net change stocks down 1 m depth over chronosequence....
Abstract Litter decomposition represents one of the largest annual fluxes carbon (C) from terrestrial ecosystems, particularly for tropical forests, which are generally characterized by high net primary productivity and litter turnover. We used data Long‐Term Intersite Decomposition Experiment (LIDET) to (1) determine relative importance climate quality as predictors rates, (2) compare patterns in root leaf decomposition, (3) identify controls on nitrogen (N) release during decay, (4) LIDET...
Abstract Fine root dynamics have the potential to contribute significantly ecosystem‐scale biogeochemical cycling, including production and emission of greenhouse gases. This is particularly true in tropical forests which are often characterized as having large fine biomass rapid rates decomposition. We examined patterns on two soil types a lowland moist Amazonian forest, determined effect decay C N trace gas fluxes. Root averaged 229 (±35) 153 (±27) g m −2 yr −1 for years 1 2 study,...
Abstract Global climate models predict significant changes to the rainfall regimes of grassland biome, where C cycling is particularly sensitive amount and timing precipitation. We explored effects both natural interannual variability experimental additions on net storage loss in annual grasslands. Soil respiration primary productivity (NPP) were measured treatment control plots over four growing seasons (water years, or WYs) that varied wet‐season length quantity rainfall. In plots, we...