ORCID Profile
0000-0002-8525-8697
Current Organisation
University of Maryland Center for Environmental Science
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Ecosystem Function | Ecological Applications | Terrestrial Ecology | Ecological Impacts of Climate Change | Ecological Physiology | Global Change Biology
ANZSRC Socio-Economic Objective (SEO)
Sparseland, Permanent Grassland and Arid Zone Soils | Climate Change Mitigation Strategies | Management of Greenhouse Gas Emissions from Plant Production | Native and Residual Pastures | Native Forests |
Related Links
Publications
Magnitude and Uncertainty of Nitrous Oxide Emissions From North America Based on Bottom‐Up and Top‐Down Approaches: Informing Future Research and National Inventories
Publisher: American Geophysical Union (AGU)
Date: 29-11-2021
DOI: 10.1029/2021GL095264
Abstract: We synthesized N 2 O emissions over North America using 17 bottom‐up (BU) estimates from 1980–2016 and five top‐down (TD) estimates from 1998 to 2016. The BU‐based total emission shows a slight increase owing to U.S. agriculture, while no consistent trend is shown in TD estimates. During 2007–2016, North American N 2 O emissions are estimated at 1.7 (1.0–3.0) Tg N yr −1 (BU) and 1.3 (0.9–1.5) Tg N yr −1 (TD). Anthropogenic emissions were twice as large as natural fluxes from soil and water. Direct agricultural and industrial activities accounted for 68% of total anthropogenic emissions, 71% of which was contributed by the U.S. Our estimates of U.S. agricultural emissions are comparable to the EPA greenhouse gas (GHG) inventory, which includes estimates from IPCC tier 1 (emission factor) and tier 3 (process‐based modeling) approaches. Conversely, our estimated agricultural emissions for Canada and Mexico are twice as large as the respective national GHG inventories.
Using model‐data fusion to interpret past trends, and quantify uncertainties in future projections, of terrestrial ecosystem carbon cycling
Publisher: Wiley
Date: 18-04-2012
AGU Advances Goes Online
Publisher: American Geophysical Union (AGU)
Date: 19-11-2019
DOI: 10.1029/2019AV000105
The Effects of Atmospheric Nitrogen Deposition on Terrestrial and Freshwater Biodiversity
Publisher: Springer Netherlands
Date: 2014
Thank You to Our 2020 Peer Reviewers
Publisher: American Geophysical Union (AGU)
Date: 03-2021
DOI: 10.1029/2021AV000426
Abstract: The editors thank the 2020 peer reviewers
Contribution of soil respiration in tropical, temperate, and boreal forests to the18O enrichment of atmospheric O2
Publisher: American Geophysical Union (AGU)
Date: 09-2003
DOI: 10.1029/2003GB002056
Prolonged tropical forest degradation due to compounding disturbances: Implications for CO2 and H2O fluxes
Publisher: Wiley
Date: 25-06-2019
DOI: 10.1111/GCB.14659
Abstract: Drought, fire, and windstorms can interact to degrade tropical forests and the ecosystem services they provide, but how these forests recover after catastrophic disturbance events remains relatively unknown. Here, we analyze multi‐year measurements of vegetation dynamics and function (fluxes of CO 2 and H 2 O) in forests recovering from 7 years of controlled burns, followed by wind disturbance. Located in southeast Amazonia, the experimental forest consists of three 50‐ha plots burned annually, triennially, or not at all from 2004 to 2010. During the subsequent 6‐year recovery period, postfire tree survivorship and biomass sharply declined, with aboveground C stocks decreasing by 70%–94% along forest edges (0–200 m into the forest) and 36%–40% in the forest interior. Vegetation regrowth in the forest understory triggered partial canopy closure (70%–80%) from 2010 to 2015. The composition and spatial distribution of grasses invading degraded forest evolved rapidly, likely because of the delayed mortality. Four years after the experimental fires ended (2014), the burned plots assimilated 36% less carbon than the Control, but net CO 2 exchange and evapotranspiration (ET) had fully recovered 7 years after the experimental fires ended (2017). Carbon uptake recovery occurred largely in response to increased light‐use efficiency and reduced postfire respiration, whereas increased water use associated with postfire growth of new recruits and remaining trees explained the recovery in ET. Although the effects of interacting disturbances (e.g., fires, forest fragmentation, and blowdown events) on mortality and biomass persist over many years, the rapid recovery of carbon and water fluxes can help stabilize local climate.
Concurrent Measurements of Soil and Ecosystem Respiration in a Mature Eucalypt Woodland: Advantages, Lessons, and Questions
Publisher: American Geophysical Union (AGU)
Date: 03-2021
DOI: 10.1029/2020JG006221
Abstract: Understanding seasonal and diurnal dynamics of ecosystem respiration (R eco ) in forests is challenging, because R eco can only be measured directly during night‐time by eddy‐covariance flux towers. R eco is the sum of soil respiration (R soil ) and above‐ground respiration (in theory, R AG = R eco − R soil ). R soil can be measured day and night and can provide a check of consistency on R eco , as the difference in magnitude and time dynamic between R eco and R soil should be explained by R AG . We assessed the temporal patterns and climatic drivers of R soil and R eco in a mature eucalypt woodland, using continuous measurements (only at night for R eco ) at half‐hourly resolution over 4 years (2014–2017). Our data showed large seasonal and diurnal (overnight) variation of R eco , while R soil had a low diurnal litude and their difference (R eco − R soil, or R AG ) had a low seasonal litude. This result implies at first glance that seasonal variation of R eco was mainly influenced by R soil while its diurnal variation was mainly influenced by R AG . However, our analysis suggests that the night‐time R eco decline cannot realistically be explained by a decline of R AG . Chamber measurements of autotrophic components at half‐hourly time resolution are needed to quantify how much of the R eco decline overnight is due to declines in leaf or stem respiration, and how much is due to missing storage or advection, which may create a systematic bias in R eco measurements. Our findings emphasize the need for reconciling bottom‐up (via components measured with chambers) and direct estimates of R eco (via eddy‐covariance method).
Modeling Denitrification: Can We Report What We Don't Know?
Publisher: American Geophysical Union (AGU)
Date: 29-10-2023
DOI: 10.1029/2023AV000990
Global soil nitrous oxide emissions since the preindustrial era estimated by an ensemble of terrestrial biosphere models: Magnitude, attribution, and uncertainty.
Publisher: Wiley
Date: 17-12-2019
DOI: 10.1111/GCB.14514
Abstract: Our understanding and quantification of global soil nitrous oxide (N
Global mapping of crop-specific emission factors highlights hotspots of nitrous oxide mitigation
Publisher: Springer Science and Business Media LLC
Date: 21-10-2021
Thank You to Our 2022 Peer Reviewers
Publisher: American Geophysical Union (AGU)
Date: 06-2023
DOI: 10.1029/2023AV000974
Abstract: The editorial board of AGU Advances thanks the in iduals who reviewed for the journal in 2022.
Thank You to Our 2019 Reviewers
Publisher: American Geophysical Union (AGU)
Date: 20-04-2020
DOI: 10.1029/2020AV000181
Magnitude and uncertainty of nitrous oxide emissions from North America based on bottom-up and top-down approaches: Informing future research and national inventories
Publisher: Wiley
Date: 02-08-2021
Toward more realistic projections of soil carbon dynamics by Earth system models
Publisher: American Geophysical Union (AGU)
Date: 2016
DOI: 10.1002/2015GB005239
Coordinated approaches to quantify long‐term ecosystem dynamics in response to global change
Publisher: Wiley
Date: 04-01-2011
Global Nitrous Oxide Budget 1980–2020
Publisher: Copernicus GmbH
Date: 17-07-2023
Thank You to Our 2021 Peer Reviewers
Publisher: American Geophysical Union (AGU)
Date: 04-2022
DOI: 10.1029/2022AV000716
Abstract: The editorial board of AGU Advances thanks the in iduals who reviewed for the journal in 2021.
COSORE: A community database for continuous soil respiration and other soil‐atmosphere greenhouse gas flux data
Publisher: Wiley
Date: 07-10-2020
DOI: 10.1111/GCB.15353
Supplementary material to Global Nitrous Oxide Budget 1980–2020
Publisher: Copernicus GmbH
Date: 09-10-2023
Quantification of global and national nitrogen budgets for crop production
Publisher: Springer Science and Business Media LLC
Date: 15-07-2021
A comprehensive quantification of global nitrous oxide sources and sinks.
Publisher: Springer Science and Business Media LLC
Date: 07-10-2020
DOI: 10.1038/S41586-020-2780-0
Abstract: Nitrous oxide (N
Carbon budget of the Harvard Forest Long‐Term Ecological Research site: pattern, process, and response to global change
Publisher: Wiley
Date: 19-10-2020
DOI: 10.1002/ECM.1423
Merging a mechanistic enzymatic model of soil heterotrophic respiration into an ecosystem model in two AmeriFlux sites of northeastern USA
Publisher: Elsevier BV
Date: 04-2018
Rate my data: quantifying the value of ecological data for the development of models of the terrestrial carbon cycle
Publisher: Wiley
Date: 2013
DOI: 10.1890/12-0747.1
Abstract: Primarily driven by concern about rising levels of atmospheric CO2, ecologists and earth system scientists are collecting vast amounts of data related to the carbon cycle. These measurements are generally time consuming and expensive to make, and, unfortunately, we live in an era where research funding is increasingly hard to come by. Thus, important questions are: "Which data streams provide the most valuable information?" and "How much data do we need?" These questions are relevant not only for model developers, who need observational data to improve, constrain, and test their models, but also for experimentalists and those designing ecological observation networks. Here we address these questions using a model-data fusion approach. We constrain a process-oriented, forest ecosystem C cycle model with 17 different data streams from the Harvard Forest (Massachusetts, USA). We iteratively rank each data source according to its contribution to reducing model uncertainty. Results show the importance of some measurements commonly unavailable to carbon-cycle modelers, such as estimates of turnover times from different carbon pools. Surprisingly, many data sources are relatively redundant in the presence of others and do not lead to a significant improvement in model performance. A few select data sources lead to the largest reduction in parameter-based model uncertainty. Projections of future carbon cycling were poorly constrained when only hourly net-ecosystem-exchange measurements were used to inform the model. They were well constrained, however, with only 5 of the 17 data streams, even though many in idual parameters are not constrained. The approach taken here should stimulate further cooperation between modelers and measurement teams and may be useful in the context of setting research priorities and allocating research funds.
Nitrogen and phosphorus additions negatively affect tree species diversity in tropical forest regrowth trajectories
Publisher: Wiley
Date: 07-2010
DOI: 10.1890/09-0636.1
Abstract: Nutrient enrichment is increasingly affecting many tropical ecosystems, but there is no information on how this affects tree bio ersity. To examine dynamics in vegetation structure and tree species biomass and ersity, we annually remeasured tree species before and for six years after repeated additions of nitrogen (N) and phosphorus (P) in permanent plots of abandoned pasture in Amazonia. Nitrogen and, to a lesser extent, phosphorus addition shifted growth among woody species. Nitrogen stimulated growth of two common pioneer tree species and one common tree species adaptable to both high- and low-light environments, while P stimulated growth only of the dominant pioneer tree Rollinia exsucca (Annonaceae). Overall, N or P addition reduced tree assemblage evenness and delayed tree species accrual over time, likely due to competitive monopolization of other resources by the few tree species responding to nutrient enrichment with enhanced establishment and/or growth rates. Absolute tree growth rates were elevated for two years after nutrient addition. However, nutrient-induced shifts in relative tree species growth and reduced assemblage evenness persisted for more than three years after nutrient addition, favoring two nutrient-responsive pioneers and one early-secondary tree species. Surprisingly, N + P effects on tree biomass and species ersity were consistently weaker than N-only and P-only effects, because grass biomass increased dramatically in response to N + P addition. The resulting intensified competition probably prevented an expected positive N + P synergy in the tree assemblage. Thus, N or P enrichment may favor unknown tree functional response types, reduce the ersity of coexisting species, and delay species accrual during structurally and functionally complex tropical rainforest secondary succession.
Acceleration of global N2O emissions seen from two decades of atmospheric inversion
Publisher: Springer Science and Business Media LLC
Date: 18-11-2019
Confronting Racism to Advance Our Science
Publisher: American Geophysical Union (AGU)
Date: 03-2021
DOI: 10.1029/2020AV000296
Abstract: As in iduals serving on the AGU Advances editorial board, we condemn racism, affirm that Black Lives Matter, and recognize that inequality is built into the systems that have allowed us to prosper. We aim to persistently foster discussion about racism, inequity, and the need to make our community more erse and inclusive. This will help AGU Advances do a better job in publishing important science that inclusively reflects the ideas and contributions of all in our community.
Biogeochemical recuperation of lowland tropical forest during succession
Publisher: Wiley
Date: 22-03-2019
DOI: 10.1002/ECY.2641
Abstract: High rates of land conversion and land use change have vastly increased the proportion of secondary forest in the lowland tropics relative to mature forest. As secondary forests recover following abandonment, nitrogen (N) and phosphorus (P) must be present in sufficient quantities to sustain high rates of net primary production and to replenish the nutrients lost during land use prior to secondary forest establishment. Biogeochemical theory and results from in idual studies suggest that N can recuperate during secondary forest recovery, especially relative to P. Here, we synthesized 23 metrics of N and P in soil and plants from 45 secondary forest chronosequences located in the wet tropics to empirically explore (1) whether there is a consistent change in nutrients and nutrient cycling processes during secondary succession in the biome (2) which metrics of N and P in soil and plants recuperate most consistently (3) if the recuperation of nutrients during succession approaches similar nutrient concentrations and fluxes as those in mature forest in ~100 yr following the initiation of succession and (4) whether site characteristics, including disturbance history, climate, and soil order are significantly related to nutrient recuperation. During secondary forest succession, nine metrics of N and/or P cycling changed consistently and substantially. In most sites, N concentrations and fluxes in both plants and soil increased during secondary succession, and total P concentrations increased in surface soil. Changes in nutrient concentrations and nutrient cycling processes during secondary succession were similar whether mature forest was included or excluded from the analysis, indicating that nutrient recuperation in secondary forest leads to biogeochemical conditions that are similar to those of mature forest. Further, of the N and P metrics that recuperated, only soil total P and foliar δ 15 N were strongly influenced by site characteristics like climate, soils, or disturbance history. Predictable nutrient recuperation across a erse and productive ecosystem may support future forest growth and could provide a means to quantify successful restoration of ecosystem function in secondary tropical forest beyond biomass or species composition.
Nitrogen Deposition Effects on Ecosystem Services and Interactions with other Pollutants and Climate Change
Publisher: Springer Netherlands
Date: 2014
Explicitly representing soil microbial processes in Earth system models
Publisher: American Geophysical Union (AGU)
Date: 10-2015
DOI: 10.1002/2015GB005188
Related Organisations
University Of Maryland Center For Environmental Science
Location: United States of America
Related Funding Activities
Discovery Projects - Grant ID: DP170102766
Start Date: 06-2017
End Date: 06-2022
Amount: $405,500.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP220102039
Start Date: 12-2022
End Date: 11-2025
Amount: $499,786.00
Funder: Australian Research Council
View Funded Activity