Site Title
How do microbial communities regulate ecosystem processes?
The overarching aim research in the Morrissey lab is to better understand natural and agricultural ecosystems through the consideration of microbial communities. Specifically, we study how environmental conditions structure microbial communities and how the composition of these communities regulate ecosystem biogeochemistry and plant performance. To accomplish these aims, we use a variety of modern genetic and bioinformatic tools in combination with assessments of microbial activity and ecosystem biogeochemistry. Because microbial community composition influences ecosystem processes, the study of microbial communities will enable us to better manage and predict ecosystem processes relevant to mitigating today’s environmental problems.
Research Directions & Current Projects
As climate change continues, altered temperature and precipitation can affect soil microorganisms and alter the cycling of carbon in soil potentially mitigating or exacerbating climate change. Soil carbon is mixture of everything from simple sugars to complex plant and microbial debris. This research will determine which microorganisms consume key types of soil carbon. Specifically, we hypothesize that soil heterotrophs can be grouped as primary decomposers that assimilate complex plant debris, secondary decomposers that assimilate microbial necromass, passive consumers that assimilate labile dissolved substrates and predatory microbes that consume live microorganism. Describing the populations of microorganisms that consume and mineralize different constituents of soil carbon may improve soil carbon models. Accurate predictions of ecosystem feedbacks to global change benefit society by allowing decision makers to prepare for the future. Additional broader impacts of this work include experiential learning opportunities for over one hundred high school students in a rural and economically depressed region of WV. Funded by NSF Ecosystem Science.
Tackling microbial biodiversity to create ecological strategies relevant to soil carbon cycling
Leveraging microbes to increase biofuel crop growth on marginal lands
Bioenergy crops represent a potentially sustainable source of energy for the future. The growth of bioenergy crops on land of poor quality (i.e., marginal lands), may alleviate the competition between bioenergy and food crops for agricultural soils as well as offer environmental and economic benefits to growers in rural areas. However marginal lands have lower yields, consequent we are researching if and how microbes can be used to enhance the growth of the bioenergy crop Miscanthus giganteus on marginal soils such as those of reclaimed mine lands. To acomplish this we aim to link changes in soil nutrient availability with microbial biodiversity and function, and further, connecting these dynamics to changes in plant yield and quality. This work is in collaboration with Dr. Zac Freedman, Dr. Louis McDonald, and Dr. Jeff Skousen. Funded by USDA AFRI Agricultural Microbiomes
Diversifying Appalachia’s Pastures to Improve Soil Health
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Many pastures in Appalachia are dominated by only a few species. Diverse plant communities are more productive, largely due to their increased stability and resilience in times of climate stress. In grasslands, diversity can increase soil carbon and improve soil health. Diverse pastures provide a more abundant and stable forage supply for cattle, which can increase operation profitability. Diverse pasture is more nutritious for livestock, reducing the risk of nutrient inadequacy. The objective of this soil health demonstration trial is to evaluate, simplify, and promote pasture diversification through reseeding as an innovative conservation strategy. We are performing demonstration trials on the farms of fifteen pasture-based cattle producers across West Virginia as well as three university-owned farms (map above). We expect the results of these on-farm trials will show that pasture diversification can improve soil health, increase soil carbon sequestration, enhance forage nutritional quality, and yield economic benefits for producers ( as shown in the conceptual model).Additionally we hope to identify when, where, and potentially why increased pasture diversity leads to the greatest, or least, soil health benefits, determine which perennial forage species persist and thrive in different environments across Appalachia and develop an interactive forage species selection tool that allows producers to identify the species best suited to their pastures based on soil, environmental, and managerial characteristics of the farm. USDA NRCS Conservation Innovation Grant for On Farm Trials.
Plant-Microbe Interactions and Soil Carbon in Temperate Forests
In this project we are investigating how ecosystems dominated tress that associated with arbuscular mycorrhizal fungi or ectomycorrhizal fungi differ in their microbial communities and soil carbon cycling responses to nitrogen availability. Nitrogen is an essential nutrient for microbes, both bacteria and fungi, that inhabit soils. However, additional nitrogen from fossil fuel buring and other human activities has altered the ability of microbes to breakdown carbon in soils. While evidence shows that nitrogen deposition has enhanced carbon storage in forest soils, it remains unclear whether these effects will persist as nitrogen deposition shifts over the region due to the success of Clean Air Act. It is also unclear why soils under arbuscular mycorrhizal trees differ in thier response to nitrogen deposition than soil under ectomycorrhizal trees. At the heart of this knowledge gap is a failure to link the impacts of additional nitrogen on the identity of microbes that live in soils (i.e., who’s there?) with their functional traits, namely the ability to breakdown, take up, and stabilize soil carbon (i.e., what they are doing?). We aim to close that knowledge gap by using measure microbial traits at the individual species level.
Phylogenetic Organization in Microbial Function
​Soil stores a large fraction of the earth’s carbon. Microorganisms break down and consume this carbon as they live and grow, converting it into the greenhouse gas carbon dioxide. Consequently, the activity of microorganism in soil has the potential to alleviate or worsen climate change. However, predictions regarding the activities of microorganisms and thus the cycling of carbon are imprecise. This is likely because the vast majority of microorganisms remain uncharacterized. This research will determine if related microorganisms behave similarly, as describing whole groups, or families, will permit efficient description of microorganisms in nature. Therefore, this work sets the stage for effective characterization of microbial diversity in order to accurately predict the cycling of carbon in soil.
Soil Organic Matter Genesis
On a global scale, soil organic matter (SOM) represent a large proportion of the carbon reservoir. Traditionally, the formation and stabilization of SOM have been view as a function of plant chemical composition (e.g., nitrogen and lignin content) and inputs into soil. Plants with high lignin and low nitrogen content lead to lower rates of decomposition by microbes and higher accumulation in soil. However, recently there has been mounting evidence that microbial transformation of labile plant constituents leads to more stabilized SOM. Since microbe derived compounds often dominate the organo-mineral SOM fraction, dead microbial cells (necromass) and microbial residues (extracellular polymeric substances) may be better protected from decomposition in the long term. Given that soil microbial communities mediates the transformation of organic carbon, it may be necessary to incorporate aspects of microbial physiology and activity in soil biogeochemical models. Microbial biomass alone can produce an abundance of stable and chemically diverse SOM. Building upon previous studies, we are interested in how the composition of microbial communities contributes to SOM formation and stabilization. Understanding the role of microorganisms in the formation of stable SOM is vital in predicting how climate change can impact soil organic carbon and carbon fluxes.
