This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2011, Intersections of Biology with Mathematical and Physical Sciences. The fellowship supports a research and training plan in a host laboratory for the Fellow at the intersection of biology with mathematics and geochemistry. The title of the research and training plan for this fellowship to Kerri Crawford is "Plant diversity and soil development in a primary successional ecosystem." The host institutions for this fellowship are the Washington University in St. Louis, Indiana University- Purdue University Indianapolis, and Indiana University Bloomington, and sponsoring scientists are Drs. Jonathan Chase, Pierre-Andre Jacinthe, and James Bever.
Soils provide services that are critical to ecosystem functioning. For example, plant growth is mediated by soil nutrients, and soils sequester a large amount of atmospheric carbon dioxide. The chemical and physical structure of soil determines its ability to fulfill these functions. Therefore, understanding what factors influence soil properties provides insights into preserving soil services. Plants and their associated microbes influence soil properties by altering nutrient cycling, soil stability, and the amount of soil organic matter. In primary successional ecosystems, such as the sand dunes along Lake Michigan - where this research is taking place, soil development has not yet occurred. This provides a unique opportunity to test what factors influence soil development. Furthermore, this experimental system allows for direct examination of soil development through time along chronosequences, where ecosystems of different ages are preserved along a spatial gradient. In this project, experimental tests of how plants and microbes influence soil development are being paired with observational studies along chronosequences, contributing to our understanding of the factors that influence soil functioning.
The training objectives include mathematical modeling and gaining knowledge of the role of soils in sequestration of carbon dioxide from the atmosphere. The broader impacts are directly applicable to restoration and conservation of the Great Lakes sand dunes, a critically endangered ecosystem. Outreach and educational activities include opportunities for undergraduates to engage in interdisciplinary environmental research.
Soils are a fundamentally important part of terrestrial ecosystems. They provide the arena for nutrient cycling and plant growth, and play a key role in the sequestration of atmospheric carbon. Soils are formed through complex interactions between rock and natural processes, such as interactions with living organisms. For example, plants and their associated microbes influence soil properties by altering nutrient cycling, soil stability, and soil organic matter. To better understand how plants and microbes influence soil development, we conducted experiments and surveys in the sand dune ecosystem along the shores of Lake Michigan. This is a primary successional ecosystem, which means that the ecosystem begins in a substrate devoid of soil and plant life. Over time, plants and soil microbes begin colonizing this habitat, and soils are formed. In the sand dunes, this sequence through time is preserved in the successive dunes parallel to the beach. Dunes closer to the beach are younger in age than dunes further away from the beach. This chronosequence makes the Great Lakes sand dunes an ideal system for studying how plants and microbes contribute to changes in the soil through time. The goals for this project were to test how plant diversity influenced soil development over a short timescale (5 years) and compare this with observational work that looked at soil development across longer time periods (100s of years). We found that the presence of the dominant plant species, a native grass – Ammophila breviligulata, increased the amount of fungal hyphae in the soil by as much as 1000%. Fungal hyphae help stabilize freely shifting sand and increase the amount of carbon sequestered in soils, suggesting that Ammophila plays a key role in the formation of soils through its interactions with soil microbes. Furthermore, the genetic diversity within this dominant plant species influenced the amount of nutrients in the soil, which likely influences the overall development of these ecosystems. Over longer timescales, we found that soil properties changed predictably though time. Future work will help elucidate the role of plants and microbes in these longer-term changes. In addition to filling gaps in our knowledge about how living organisms contribute to soil development, this work is directly applicable to restoration and conservation of the Great Lakes sand dunes, a critically endangered ecosystem. Furthermore, it sheds light on the importance of preserving and restoring plant communities for soil carbon sequestration in these dune systems. Outreach and education activities related to this project have provided opportunities for four undergraduate students and two high school students to engage in interdisciplinary research.
