Brent E. Ewers - US grants

0405381
Ewers

It is clear from recent reports by the water and carbon groups associated with the United States Global Change Research Program that accurate predictions of canopy stomatal conductance in forested systems are critical for the understanding of land surface - atmosphere fluxes and how they are affected by climate and land use changes. Indeed, land use changes are producing more fragmented landscapes and these are not readily represented in current land surface models. Current forest flux models were developed under the paradigm of research in which uniform forest stands are identified, flux measurements are made in the centers of these stands, and then what is learned here is extrapolated to the entire stand and beyond. This approach is neither necessary nor justified given the spatial complexity of vegetative communities. This project
seeks to develop a conceptual model of forest transpiration that embraces the inherent spatial variability of stomatal control while retaining a tractable measure of generalizability that is the hallmark of empirical models of stomatal conductance. Our conceptual model is based on the idea that canopy stomatal conductance is regulated primarily by water potential when water fluxes are high and of significant hydrologic import. We propose that species plasticity in canopy stomatal conductance, which determines its spatial variability and challenge for quantifying, follows a linear relationship that is keyed off of an easily quantifiable reference conductance
0405381
Ewers

It is clear from recent reports by the water and carbon groups associated with the United States Global Change Research Program that accurate predictions of canopy stomatal conductance in forested systems are critical for the understanding of land surface - atmosphere fluxes and how they are affected by climate and land use changes. Indeed, land use changes are producing more fragmented landscapes and these are not readily represented in current land surface models. Current forest flux models were developed under the paradigm of research in which uniform forest stands are identified, flux measurements are made in the centers of these stands, and then what is learned here is extrapolated to the entire stand and beyond. This approach is neither necessary nor justified given the spatial complexity of vegetative communities. This project
seeks to develop a conceptual model of forest transpiration that embraces the inherent spatial variability of stomatal control while retaining a tractable measure of generalizability that is the hallmark of empirical models of stomatal conductance. Our conceptual model is based on the idea that canopy stomatal conductance is regulated primarily by water potential when water fluxes are high and of significant hydrologic import. We propose that species plasticity in canopy stomatal conductance, which determines its spatial variability and challenge for quantifying, follows a linear relationship that is keyed off of an easily quantifiable reference conductance

As the world's second largest terrestrial biome, the boreal forest plays a crucial role in the global water cycle. The goal of this project is to quantify and understand biological atmospheric losses of water from boreal forests recovering from natural wildfire disturbances. Biological control occurs because plants regulate the amount of water lost while photosynthesizing. Current models of evaporated water into the atmosphere from boreal forests are to simplistic because of a lack of data separating water lost from trees versus mosses, of which the former has markedly different controls than the latter over water loss.

This project will enable the scientific and land management communities to assess how much complexity is required to adequately predict water losses from boreal forests that are experiencing and may continue to experience increased wildfire frequency. The project will serve as an ideal training ground for future scientists and land managers who work on systems that may modify the vegetation and thus water cycle by training post-docs, graduate and undergraduate students. The project will continue current efforts by the project leaders to integrate science and education through ties with local native peoples, high schools and community colleges.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

Quantifying the Effects of Large-Scale Vegetation Change on Coupled Water, Carbon and Nutrient Cycles: Beetle Kill in Western Montane Forest
We are quantifying how rapid, extensive changes in forest structure and composition associated with Mountain Pine Beetle (MPB) infestation of western montane forests affect the coupling of water, carbon, and nitrogen cycles. MPB infestation and associated fungal pathogens radically change ecosystem structure by killing host trees, altering surface energy and water partitioning, reducing carbon uptake, and putting organic matter into soil on short and long time scales. The widespread extent of this disturbance presents a major challenge for governments and resource managers who must respond to the changes, yet lack a predictive understanding of how these systems will respond to the disturbance over various temporal and spatial scales. This disturbance allows us to test emerging theories of direct and indirect effects of vegetation change on coupled biogeochemical cycles following a disturbance that initially changes only the amount of living biomass while leaving soil hydrologic and chemical characteristics unchanged. By working at sites with different levels of MPB impact, we are evaluating how the dramatic loss of tree function both directly (i.e. transpiration and carbon fixation) and indirectly (i.e. snow capture, redistribution, and surface energy balance) affects water, carbon and nitrogen cycling.

Our work is organized around two, broad questions that require both an interdisciplinary approach and close integration of observation and modeling. How do changes in vegetation structure associated with MPB alter the partitioning of energy and water? And How do these changes in energy and water availability affect local to regional scale biogeochemical cycles? We have assembled a diverse team of biogeochemists, ecologists, hydrologists, and atmospheric scientists to address these questions using measurements, modeling tools, and conceptual approaches from each discipline. Our approach includes intensive, coordinated hydrological, biogeochemical, and ecological observations designed to quantify the internal coupling of water, carbon, and nutrient cycling, as well as how these processes are expressed in both land surface-atmosphere exchanges and catchment solute export. These observations are closely integrated with two process models, one from the landsurface community and one from the catchment community, to evaluate our current understanding of how vegetation change alters coupled cycles. To extend our work beyond the relatively short time-scale of our observations, we coordinate with several ongoing projects, including the Boulder Creek CZO and the Niwot Ridge LTER.

By quantifying both the biological and physical controls that forest vegetation has on water and biogeochemical cycles, our project will both improve our basic understand of the coupling between water, energy, carbon, and nitrogen. Through coordination with land surface and catchment modeling communities we will incorporate this knowledge into the broader community. Our educational activities build on successful efforts at all institutions, while coordination with land and water resource managers will ensure our knowledge is transferred to the applied science community.

This Research Infrastructure Improvement (RII) Track-1 award establishes the Wyoming Center for Environmental Hydrology and Geophysics (WyCEHG), a center based at the University of Wyoming and involving Wyoming's community colleges, the Wind River Tribal College, the Arapaho Ranch, Jackson State University (Mississippi), and several federal, state and private business partners. The specific focus is to improve the understanding of the mechanisms by which water is transformed from precipitation (snow and rain) into river flow, groundwater recharge, or soil moisture, and how these mechanisms respond to natural and anthropogenic changes.

Intellectual Merit
This project focuses on developing a multidisciplinary center to enable a comprehensive research program linking surface and subsurface watershed hydrology, geophysics, remote sensing, and computational modeling. Scientific goals include improving the understanding of mountain front hydrology, the mechanisms by which disturbances affect water flux, and the integrated modeling of the fate and transport of water. Realistic computer models of hydrological systems are being generated, informed by geophysical data of the subsurface acquired at the watershed scale, and validated by geochemical, hydrological, and ecological monitoring data. The project team is developing an open-access, national facility for hydrogeophysics that includes state-of-the-art instrumentation, to be sustained after the award ends by an industry endowment.

Broader Impacts
WyCEHG is designed to address pressing water-related issues in WY. It supports water research in areas of key importance to the state, generating products and tools of use to water resource managers charged with allocating scarce resources and forecasting water deliveries in an environment of profound hydrological change. Methods, models, observational platforms, and information relevant to decision support are shaped by, and communicated to, decision makers. A major focus of the project is to meet educational and outreach needs in WY through an integrated program fully coupled to the scientific agenda. The project encompasses education initiatives, diversity programs, workforce development, public forums, and stakeholder engagement. Graduate student training includes the new Ph.D. Program in Hydrologic Sciences at the University of Wyoming. Also included is a vigorous mentoring and recruitment effort to attract Native American, Hispanic, African-American, and female students, along with persons with disabilities, to the STEM workforce.

The sustainability of the Panama Canal is intricately connected with land-use. The Canal was created by damming the Chagres River, creating Lake Gatun. Each ship passing through the Canal requires release of water from Lake Gatun, so reliable operation of the Canal requires reliable runoff from the Panama Canal watershed. This is particularly true during the extended dry season, when rainfall essentially stops. Furthermore, floods during the wet season can cause closure of the Canal. The Panama Canal is undergoing a significant expansion to allow passage by larger ships. Canal operations are a vital US interest. Approximately 20 percent of trade between the U.S. and Asia passes through the Panama Canal representing five percent of global trade, and the Canal enables a large number of US jobs. However, the Canal expansion will require more water despite the new high efficiency locks. Land management in the Panama Canal Watershed influences how much and when water drains into Lake Gatun and the Canal. This project will map the flow of land use policy incentives from authorities like Panama Canal Authority, through landholder response, to changes in land use and cover, to the effects of flow into the Canal. This will help predict human and hydrological responses to policy and identify the least cost approach to providing hydrologic ecosystem services. This project includes international components conducted in the country of Panama and is funded in part with funds from NSF ISE funds.


This project will evaluate the hydrology of the Panama Canal region as a response to land use policy incentives from authorities like Panama Canal Authority, through landholder response, to changes in land use and cover, to the effects of flow into the Canal. Preliminary results suggest that land management decisions alter paths available for water to flow from the land into the Canal. These "preferential flow paths" are created by soil cracking in the dry season, and by biological factors such as plants, animals, and microbes. Conversion of grazing lands to forest seems to increase the amount of water flowing through the soil. This may increase groundwater recharge, an important source of dry season river flows. Forest land cover may reduce flooding in the wet season. The project will collect watershed-scale hydrologic data in different land uses and covers, and analyze those data to quantify the roles of deforestation and grazing on hydrologic behavior. Researchers will measure the factors affecting participation in an existing land-use incentive system to implement land management systems that may improve the flow regime to the Canal. The findings from the physical and socio-economic studies will be merged into a hydro-socio-economic model to predict future water resources availability in the Panama Canal watershed, driven by different land-management and climate scenarios.

Soil microbial communities represent a largely untapped source for yield improvement in crops. In comparison to plants grown without microbes in the soil, yields can be twice as great when plants are grown with their full complement of soil microbes. Microbes may improve plant growth by making soil nitrogen more available to plants. From the point of view of plant growth and eventual yield, nitrogen is important as it is a critical component of one enzyme, Rubisco, which takes carbon dioxide from the air and converts it to sugars for growth through the process of photosynthesis. To identify how microbes improve plant growth, the current research examines 1. how microbes modify soil chemistry, 2. what plant genes are selectively turned on in response to the presence of microbes, 3. how plant processes like photosynthesis respond to microbes, and 4. what the identity and functions are of the soil microbes. Connecting results from these four sets of data will reveal what it is that promotes plant growth, from the soil to the whole-plant level. This research also includes ways to predict plant growth and yield in response to soil microbes when different amounts of nitrogen are added to the soil, which should enable reduced use of fertilizers. The plant being studied is Brassica rapa, which is grown around the world as root (turnip), leaf (cabbage, pak choi), and oilseed (canola) crops; because of the diverse uses of this crop, results from this species are expected to apply to a wide range of other crops. Soil microbes are an important part of the ecosystem, and connect plants to the physical environment. While much is known about the plants in natural and agricultural settings, less is known about the distributions, types, and functions of beneficial soil microbes, and how they help crops cope with poor growing conditions such as drought or lack of nitrogen. The current research fills these knowledge gaps, and will provide recommendations on how to manage soils for beneficial microbes. Broader impacts to this work include development of guided tours within the Williams Conservatory, Geology Museum, and Berry Center for Biodiversity at the University of Wyoming as well as teaching modules related to the study of evolution and crop domestication.

Soil microorganisms serve a range of ecosystem services that promote plant growth under stressful abiotic conditions, including nitrogen limitation. Yet, soil microbial communities represent a largely untapped source for yield improvement in crop species. Analyzing plant transcriptomic and physiological responses to taxonomically and functionally diverse soil microbiomes will provide insights as to the mechanisms by which microbes enhance plant growth. Further, Bayesian systems modeling of plant transcriptomic, hydraulic, and gas-exchange responses to the soil microbial environment can provide a predictive understanding of plant growth promotion by microbes under variable nitrogen amendments. When grown with an intact vs. reduced soil microbiome, crops of Brassica rapa upregulate gas-exchange and increase biomass accumulation up to two-fold, suggesting one physiological link between plant transcriptomic responses to soil microbes and eventual plant biomass accumulation. Because B. rapa is domesticated as root, leaf, and oilseed crops, mechanisms of growth promotion characterized in this species could translate to a range of other crops. Further, the microbiome associated with the rhizosphere of B. rapa is highly differentiated from that of bulk soils more distant from the roots, suggesting the species is an effective model for studying the assembly dynamics, identity, and function of beneficial plant-associated soil microbes. Using next-generation amplicon and metagenome sequencing of rhizosphere DNA in combination with plant genomic, transcriptomic, and physiological experiments, the research will characterize mechanisms of plant growth promotion by soil microbes and test predictive systems models. The research addresses the PGRP 2014 focal areas: to develop a genome-level link between genes and physiological functions in crop plants and to develop a genome to systems-level understanding of plant-environmental interactions, especially with respect to abiotic stress. Broader impacts to this work include development of guided tours and teaching modules related to crop domestication and improvement as well as development of management practices for beneficial microbes. Information on this project can be accessed at www.RhizoBiomics.org.

Rising demand for high quality food crops due to increasing world populations along with more likely temperature and drought stress requires further crop improvements from breeding programs. A major limitation to these programs is an understanding of how the genetic information affects the characteristics of plants that improve the amount of edible portions. Moreover, the predictive understanding is even less if the plants are placed in new, stressful environments like low rainfall or high temperature. A likely avenue of inquiry to improve breeding is to better connect how information stored in genes becomes traits of plants that combine their biology, such as photosynthetic rate or the amount of resources allocated to an edible root, with the physical world, such as the amount of water available or an excessive heat wave. These connections are currently often made in a way that requires new data collection for every new crop plant or environment such as a new soil, new temperature range or even a new improved line that shows variation in the amount of resources the plant allocates to an edible root. This continuous need for new information ultimately slows down the breeding program and the ability of plant scientists to quickly respond to the needs of society. This project will test a new approach that uses large amounts of data to calculate the probability that a particular plant characteristic will be displayed by a given plant line under various environmental conditions. Specifically, the project will measure plant performance continuously by sending electrical pulses through plants, integrating the data generated with large data sets that show which genes are active as well as the level of biologically relevant molecules that contribute to major metabolic pathways within the plants at any given time. This new approach requires high performance computing to test many times how the probability of phenotypic improvement in the crop may occur. These high performance computing approaches will become a core part of a modern, competitive workforce. In this regard, the project will provide workshops for high school teachers in the use of high performance yet open source computing tools in their classrooms. In addition, the project will develop experimental and computational modules in biological and quantitative learning for students in grades 6-12 using the highly successful Wisconsin FastPlants system (http://www.fastplants.org/).

With increasing world populations, genetic advances to improve crop growth, yield and resistance to abiotic stress are a pressing need. Limiting the speed of crop improvement is a crucial knowledge gap regarding biophysical processes that modulate the relationship between the genome and phenome, hindering the ability to predict the phenotype of novel genotypes in novel environments. As a first step towards bridging this gap, a combination of high-throughput phenotyping and biophysical process modeling will incorporate allelic variation at key genes affecting plant carbon metabolism, hydraulics, and resource allocation, all of which are known to impact drought- and heat-stress resistance in plants. Variable selective pressures during crop diversification have caused extensive phenotypic variation among B. rapa crops, making it an excellent study system to both connect organ-level measures both down to the level of transcriptomic and metabolomic phenotypes and up to yield and to test predictive process models. Process models will be developed and refined using the mechanistic links that connect cell processes and ultimately whole plant physiology to regulatory intermediates such as metabolites and gene transcripts. If successful, the models developed will enable prediction of whole-plant stress-response phenotypes in heterogeneous genotypes and environments. The goals of the project are to: 1) deploy a novel high-throughput and real-time phenotyping method to measure diel physiological dynamics in eight B. rapa parental Nested Association Mapping (NAM) lines under drought- and heat-stress conditions; 2) predict yield in a Recombinant Inbred Line (RIL) population of B. rapa using a biophysical process model of carbon metabolism, hydraulics and resource allocation to test systems-level links between circadian, transcriptomic, metabolomic, and physiological QTL; and 3) test the predictive ability of the biophysical process model under heat- and drought-stress environments using the RIL population used in Aim 2. All data and resources generated in this project will be made accessible to the public through long-term open access repositories such as Project Github and the NCBI Short Read Archive.

Non-technical Description
Microbial organisms are ubiquitous and abundant in soil and aquatic environments. One teaspoon of soil may contain over a billion bacteria, belonging to thousands of distinct species. These organisms play essential roles in cycling nutrients, decomposing organic matter, and determining the fate of pollutants released by human activities. This project will collect samples of microbes from thousands of sites across Wyoming that differ in their local climate, land use, and plant life. The samples will be analyzed to better understand the environmental roles of the microbes and their responses to changes in precipitation, soil properties, and land use. Species composition and ecological relationships to the ecosystem will be determined using DNA, RNA, and protein sequencing. Statistical methods will be used to uncover the relationships between microbes and how the overall ecosystems function. The results will help predict how different regions will respond to environmental disturbances and provide policy makers tools to better manage natural resources. The project will also train workers in how to handle the huge volumes of data generated by such research; these skills will be transferrable to many sectors of the Wyoming economy. Outreach efforts to Native American, Latino, and hearing-impaired students will promote diversification of the workforce trained in STEM fields.

Technical Description
The overarching aims of this project are to advance process-based understanding of soil and freshwater microbiomes, to develop cutting-edge data-science training and research and development capacity in Wyoming, and to position the University of Wyoming as a national leader in microbial ecology and data science. To define the causal factors that determine microbial distributions, over nineteen thousand samples of soil-, water-, and plant-associated microbes will be collected and processed, taking advantage of environmental gradients that exist across the state. Samples will be studied using a variety of ?omic? (genomic, transcriptomic, proteomic, metabolomic) and biogeochemical technologies, including enzymatic assays and stable isotope probing. Relationships between microbial life and ecological consequences will be modeled and tested by statistical and experimental means. Investments in equipment infrastructure, inter-disciplinary training for diverse students and postdocs, and new faculty hires will enhance the research capacity of Wyoming. The focus on data science training will serve the technology workforce needs of Wyoming and benefit the state economy.

Over the past two decades, forests in the western US have experienced increases in bark beetle infestations and higher incidence of forest fires. The resulting tree mortality produces ecosystem responses that affect water quantity and quality, carbon storage, and nutrient cycling, with implications for future forest production and health. Understanding how these two stresses affect forests is critical to the management and availability of water in the western US. This award will significantly contribute to ecosystem models that predict where and how fast carbon, nitrogen and water move in these forests. Results from this study will be shared with regional water and forest managers using the Wyoming Water Forum. Underrepresented and first-generation pre-college students will be involved in the project through the University of Wyoming "Summer Research Apprentice Program".


This award will quantify carbon and water fluxes in relation to post-beetle fire intensity, partitioning these fluxes into contributions from the understory plants, overstory plants, and soil. The researchers will further assess the interactive effects between post-beetle fire and vegetation regrowth, specifically in regard to soil water and available soil N. The researchers will take advantage of a recent fire that burned through a beetle-affected lodgepole pine forest in Chimney Park Wyoming. The heterogeneous distribution of burn severity and existing pre-burn data provide a unique opportunity to understand the physical and biological processes that control the water, carbon, and nitrogen cycles within a forest ecosystem following sequential and interacting disturbances. The researchers will measure ecosystem pools and fluxes of carbon dioxide, water, and nitrogen in forest patches of different post-beetle burn intensities (bark beetles only, bark beetles plus understory fire, bark beetles and stand replacing fire) using eddy covariance, sap flow, electrical resistivity tomography, vegetation surveys, and biogeochemical techniques. This study will leverage existing equipment and benefits from an extensive pre-disturbance data set. This award will develop predictions and attribution to biological (e.g. transpiration controlled by plant conductance) and/or physical (e.g. soil evaporation and interception from bare branches) drivers in these forests.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.