Public Abstract

DE-SC0025253: Synthesis of existing tropical root data: How do natural, episodic disturbances alter tropical forest carbon cycles via changes in belowground dynamics?

Award Status: Active

Institution: Regents of the University of Minnesota, Minneapolis, MN
UEI: KABJZBBJ4B54
DUNS: 555917996

Most Recent Award Date: 09/04/2024
Number of Support Periods: 1
PM: Stover, Daniel

Current Budget Period: 09/01/2024 - 08/31/2026
Current Project Period: 09/01/2024 - 08/31/2026
PI: Powers, Jennifer

Supplement Budget Period: N/A

Public Abstract

Synthesis of existing tropical root data: How do natural, episodic disturbances alter tropical forest carbon cycles via changes in belowground dynamics? Jennifer Powers, University of Minnesota (Principal Investigator) Daniela Cusack, Colorado State University (Co-Investigator) Kelly Andersen, Colorado State University (Collaborator) Jennifer Holm, Lawrence Berkeley National Lab (Collaborator) Daniela Yaffar, Oak Ridge National Lab (Collaborator) Laynara Lugli, Technical University of Munich, (Collaborator) Amanda Cordeiro, Colorado State University (Collaborator) Disturbance is a key feature of the natural history of all ecosystems, and those in tropical latitudes are no exception. Tropical ecosystems have experienced disturbances such as wildfires, droughts, flooding, and cyclones (also known as hurricanes) for millennia, and many species are adapted to these disturbance regimes. However, tropical ecosystems are currently experiencing diverse and more extreme changes in abiotic conditions and disturbance events, with an intensification observed in recent years. While many studies have focused on understanding how aboveground properties of ecosystems such as plant biomass, plant species composition, and/or functional characteristics or traits of species respond to different disturbance regimes, our understanding of the consequences of natural, episodic disturbances on belowground processes and properties has lagged behind our understanding of aboveground processes. Plant roots fulfill multiple ecological roles: they anchor plants in the soil, facilitate water and nutrient uptake, host symbiotic relationships with mycorrhizal fungi, in some plant species host nitrogen fixing bacteria, and act as a direct conduit of organic carbon to the soil via rhizodeposition and root death, which has important implications for soil carbon storage and dynamics. Roots respond to ecosystem disturbance events such as those described above, which may alter their ecological function. Thus, roots directly mediate ecosystem feedbacks to climate change via shifts in water, nutrient, and carbon cycles after episodic disturbance, both directly and through linkages to aboveground and other soil responses. We estimate that there are now sufficient data to understand how tropical root stocks, traits, and dynamics respond to disturbances across the large gradients in soil fertility and mean annual precipitation that characterize tropical ecosystems. Unfortunately, these data have not yet been collated and synthesized. Thus, our main objective is to synthesize existing data from published studies to determine how a range of episodic disturbances in tropical forests affect belowground dynamics and develop a new mechanistic understanding of feedbacks between disturbances and the carbon cycle. Our database will be compatible with and freely available to the public through the DOE-supported FRED (Fine-Root Ecology Database) and will help resolve uncertainties in how root dynamics are modeled in response to disturbances. We will complete this project using best practices for literature review and synthesis that we developed through our inclusive and successful TropiRoots Collaborative Network. First, we will renew our literature search to add to the 700+ papers that we have already identified. A postdoc will lead a team of undergraduate student researchers to select and extract data from the papers with disturbances. In our data extraction, we will include all root data and ancillary data such as spatial coordinates, climate, and soil characteristics, as well as any information on plant species composition and functional traits, biodiversity, and aboveground variables such as basal area and carbon stocks. Second, we will use this dataset to address three core hypotheses: H1) rainfall regimes and soil properties such as phosphorus availability modify root responses to disturbance, H2) the duration and type of disturbance agent determine the extent of root responses, with disturbances such as flooding and cyclones having larger effects on root systems than fire, drought, heat waves, or nitrogen deposition, and H3) the diversity of plant species and their traits mediate the community-level effects of changes in roots on ecosystem carbon stocks and fluxes such that higher diversity ecosystems are more buffered against changes in root characteristics following disturbance in comparison to lower diversity ecosystems. We will use a structural equation modelling approach to evaluate the mechanistic relationships between root responses and disturbances, and which environmental factors moderate those relationships. Next, we will use the database to train and validate the DOE-supported FATES (Functionally Assembled Terrestrial Ecosystem Simulator) model to improve how roots are represented for tropical ecosystems. Last, our dataset will be uploaded and freely available via FRED, DataDryad, and ESS-DIVE, allowing for future analysis and use by the global community. Thus, our project advances conceptual and dynamic vegetation models and data availability to develop a novel understanding of root responses to disturbances in tropical ecosystems.

Synthesis of existing tropical root data: How do natural, episodic disturbances alter tropical forest carbon cycles via changes in belowground dynamics?

Jennifer Powers, University of Minnesota (Principal Investigator)
Daniela Cusack, Colorado State University (Co-Investigator)
Kelly Andersen, Colorado State University (Collaborator)
Jennifer Holm, Lawrence Berkeley National Lab (Collaborator)
Daniela Yaffar, Oak Ridge National Lab (Collaborator)
Laynara Lugli, Technical University of Munich, (Collaborator)
Amanda Cordeiro, Colorado State University (Collaborator)

Disturbance is a key feature of the natural history of all ecosystems, and those in tropical latitudes are no exception. Tropical ecosystems have experienced disturbances such as wildfires, droughts, flooding, and cyclones (also known as hurricanes) for millennia, and many species are adapted to these disturbance regimes. However, tropical ecosystems are currently experiencing diverse and more extreme changes in abiotic conditions and disturbance events, with an intensification observed in recent years. While many studies have focused on understanding how aboveground properties of ecosystems such as plant biomass, plant species composition, and/or functional characteristics or traits of species respond to different disturbance regimes, our understanding of the consequences of natural, episodic disturbances on belowground processes and properties has lagged behind our understanding of aboveground processes.

Plant roots fulfill multiple ecological roles: they anchor plants in the soil, facilitate water and nutrient uptake, host symbiotic relationships with mycorrhizal fungi, in some plant species host nitrogen fixing bacteria, and act as a direct conduit of organic carbon to the soil via rhizodeposition and root death, which has important implications for soil carbon storage and dynamics. Roots respond to ecosystem disturbance events such as those described above, which may alter their ecological function. Thus, roots directly mediate ecosystem feedbacks to climate change via shifts in water, nutrient, and carbon cycles after episodic disturbance, both directly and through linkages to aboveground and other soil responses. We estimate that there are now sufficient data to understand how tropical root stocks, traits, and dynamics respond to disturbances across the large gradients in soil fertility and mean annual precipitation that characterize tropical ecosystems. Unfortunately, these data have not yet been collated and synthesized. Thus, our main objective is to synthesize existing data from published studies to determine how a range of episodic disturbances in tropical forests affect belowground dynamics and develop a new mechanistic understanding of feedbacks between disturbances and the carbon cycle. Our database will be compatible with and freely available to the public through the DOE-supported FRED (Fine-Root Ecology Database) and will help resolve uncertainties in how root dynamics are modeled in response to disturbances.

We will complete this project using best practices for literature review and synthesis that we developed through our inclusive and successful TropiRoots Collaborative Network. First, we will renew our literature search to add to the 700+ papers that we have already identified. A postdoc will lead a team of undergraduate student researchers to select and extract data from the papers with disturbances. In our data extraction, we will include all root data and ancillary data such as spatial coordinates, climate, and soil characteristics, as well as any information on plant species composition and functional traits, biodiversity, and aboveground variables such as basal area and carbon stocks. Second, we will use this dataset to address three core hypotheses: H1) rainfall regimes and soil properties such as phosphorus availability modify root responses to disturbance, H2) the duration and type of disturbance agent determine the extent of root responses, with disturbances such as flooding and cyclones having larger effects on root systems than fire, drought, heat waves, or nitrogen deposition, and H3) the diversity of plant species and their traits mediate the community-level effects of changes in roots on ecosystem carbon stocks and fluxes such that higher diversity ecosystems are more buffered against changes in root characteristics following disturbance in comparison to lower diversity ecosystems. We will use a structural equation modelling approach to evaluate the mechanistic relationships between root responses and disturbances, and which environmental factors moderate those relationships. Next, we will use the database to train and validate the DOE-supported FATES (Functionally Assembled Terrestrial Ecosystem Simulator) model to improve how roots are represented for tropical ecosystems. Last, our dataset will be uploaded and freely available via FRED, DataDryad, and ESS-DIVE, allowing for future analysis and use by the global community. Thus, our project advances conceptual and dynamic vegetation models and data availability to develop a novel understanding of root responses to disturbances in tropical ecosystems.