Land and Ecosystem Management
Statement of Research:
My research explores (1) fire severity and postfire treatment effects on soil microbial communities in ponderosa pine forests, (2) response of soil fungi to restoration thinning and prescribed fire, (3) biological and functional diversity of mycorrhizal fungi in pine forests with impending climate change, (4) microbial interactions with native and nonnative plant species, and (5) fungal diversity in old-growth and younger managed stands.
The web of life belowground
The web of life that exists belowground and out of sight may be the final frontier for forest ecologists. Among the many unknowns in this realm are the thousands of species of ectomycorrhizal fungi, those fungi that have mutual-need associations with both trees and mammals. The richness and diversity of ectomycorrhizal fungi species contribute directly to biodiversity, and also have a significant impact on forest function through their interactions with other species. These fungi are difficult to survey and identify; however, station research has established better understanding of how fungi interact with forests of all ages. The results suggest that fungi species change as forests age, and that unique species assemblages are found in each stage of forest development. The findings provide data to address critical conservation biology questions such as how well legacy structures provide for aspects of biodiversity. Such knowledge is essential for making sound management decisions about the conservation of forest species, the organisms they support, and forest ecosystem sustainability.
Link to publications:
Elliott, J.C.; Smith JE, Cromack, K. Jr.;, Chen, H.; McKay, D. 2007. Chemistry and ectomycorrhizal communities of coarse wood in young and old-growth forests in the Cascade Range of Oregon. Canadian Journal of Forest Research. 37: 2041–2051.
Smith, J.E.; Molina, R.; Huso, M.; Luoma, D.; McKay, D.; Castellano, M.A.; Lebel, T.; Valachovic, Y. 2002. Species richness, abundance, and composition of hypogeous and epigeous ectomycorrhizal fungal sporocarps in young, rotation-age, and old-growth stands of Douglas-fir (Pseudotsuga menziesii) in the Cascade Range of Oregon, U.S.A. Canadian Journal of Botany. 80: 186–204.
Trappe, J.M.; Molina, R.; Luoma, D.L.; Cázares, E.; Pilz, D.; Smith, J.E.; Castellano, M.A.; Miller, S.L.; Trappe, M. 2009. Diversity, ecology, and conservation of truffle fungi in forests of the Pacific Northwest. Gen. Tech. Rep. PNW-GTR-772. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. Gen. 194 p.
Science Findings Issue 66
Science Findings Issue 118
Microbial and plant recovery in severely burned soils
Soil exposed to prolonged intense heat during a wildfire turns a distinctive red color. The heat volatilizes soil nutrients and kills subterranean microbial communities. Patches of severely burned red soil are found most frequently in areas that were heavily covered with down, dead wood before the fire. It has long been thought that exposure to such heat sterilized soil, leaving it more susceptible to invasion by nonnative plant species than less severely burned soils. Station scientists and collaborators initiated several soil-related studies after the 2003 B&B Fire Complex in the central Oregon Cascades to better understand the relationships among fire severity, soil microbial communities, and invasive nonnative plant species. They found that, although soil nutrients and microbial abundance were greatly reduced, severely burned red soils were not sterile. They also found that growth of invasive plant species is limited by nutrient availability, rather than microbial diversity or mycorrhizal relationships. In the laboratory using soils from the study site, scientists found that nonnative species grew bigger than native species. However, nonnative plants grown in red soils were smaller than those grown in less severely burned black soils. Native plant growth did not differ in the red or black soil, raising questions about how nonnative and native plants will grow and compete long term in nutrient limited environments.
Link to publication:
Hebel, C.L.; Smith, J.E.; and Cromack, K.Jr. 2009. Invasive plant species and soil microbial response to wildfire burn severity in the Cascade Range of Oregon. Journal of Applied Soil Ecology 42: 150-159.
Science Findings Issue 124
Belowground impacts of prescribed fires
A century of fire suppression has resulted in dense fuel loads within the dry pine forests of eastern Oregon. To alleviate the risk of stand-replacing wildfire, forest managers are using prescribed fire and thinning treatments. Until recently, the impact of these fuel treatments on soil productivity has been largely unknown. Such information is essential for making sound management decisions about the successful reintroduction of fire to the ecosystem to retain biodiversity of soil fungi and achieve the desired future condition of large ponderosa pines with low fuel loads. In a pair of studies, led by researchers at the Pacific Northwest Research Station Forestry Sciences Laboratory in Corvallis, Oregon, novel molecular techniques were utilized to investigate the response of soil ecosystems to prescribed burning and thinning. The research compared impacts of the season of burn and various combinations of fuel-reducing treatments. Results suggest that overly severe fires can damage soil productivity and that less intense fires can be used to gradually reduce accumulations of fuel. The findings are currently being implemented in decisions about forest management and contribute important new information to the science.
Link to publications:
Smith, J.E.; McKay, D.; Brenner, G.; McIver, J.; Spatafora, J. 2005. Early impacts of restoration treatments on the ectomycorrhizal fungal community and fine root biomass in a mixed-conifer forest. Journal of Applied Ecology. 42: 526–535.
Smith J.E; McKay, D.; Niwa, C.G.; Thies, W.G.; Brenner, G.;, Spatafora, J.W. 2004. Short-term effects of seasonal prescribed burning on the ectomycorrhizal fungal community and fine root biomass in ponderosa pine stands in the Blue Mountains of Oregon. Canadian Journal of Forest Research. 34: 2477–2491.
Science Findings Issue 82
Soil microbes undaunted by the impacts of harvesting fire-killed trees
Severe forest wildfires have prompted the need to evaluate the effect of postfire treatments on forest ecosystem recovery. Disturbances such as fire and harvesting can affect the abundance, activity, and composition of soil microbial communities, thereby contributing to changes in nutrient cycling, organic matter decomposition rates, and ecosystem carbon accrual. Postfire logging recoups the economic value of timber killed by wildfire, but whether such forest management activity supports or impedes forest recovery is unclear. Such information is essential to finetune postfire treatment methods and speed the forest recovery process. Station scientists and collaborators explored the impact of mechanical logging and subsoiling after wildfire on soil bacterial and fungal communities and other measures influencing soil productivity. Findings indicate that nutrients critical to soil productivity were reduced by mechanical applications used in timber harvesting, yet soil bacteria and fungi, essential to mediating decomposition and nutrient cycling, appeared resilient to mechanical disturbance. The findings are currently being implemented in decisions about forest management and contribute important new information to the science.
Link to publication:
Jennings, T,N,; Smith, J.E.; Sulzman, E.;, Cromack, K. Jr.;, McKay, D.; Caldwell, B.; Beldin, S. 2012. Impact of postfire logging on soil bacterial and fungal communities and biogeochemistry in a mixed-conifer forest in central Oregon. Plant Soil. 350(1): 393–411.
Willows host fungi that help clean up polluted soil and water
Reestablishing native vegetation on land contaminated by heavy metals is a challenge for land managers. Toxic levels of cadmium, lead, nickel, and copper affect plant metabolism and photosynthesis, and possibly affect belowground fungal communities and their associations with plant roots. A collaborative research project between Slovenian and American scientists focused on distinct mycorrhizal fungal groups associated with plant hosts growing on heavy metal enriched sites. Willows have been successfully used for revegetating heavily contaminated land and are known to form mycorrhizal associations with several distinct groups of fungi. The scientists found that these mycorrhizal associations may add to the adaptability of willows on soil polluted with heavy metal. This research provides insights on the ability of willows to clean up harmful toxins in water and soil and will contribute to the success of projects around the world that are using green plants to remove or neutralize pollutants from the environment.
Link to publication:
Regvar, M.; Likar, M.; Piltaver, A.; Kugonič, N.; Smith, J.E. 2010. Fungal community structure under goat willows (Salix caprea L.) growing at a metal polluted site: the potential of screening in a model phytostabilisation study. Plant Soil. 330: 345-356.
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