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2007 Soil and Water Conservation Society - Soil Quality Workshop

"Soil Quality: the Foundation for Natural Resource Quality"


Lyn Townsend and Terry Aho
USDA NRCS, Portland, OR

Forested soils have biotic and abiotic attributes that developed during primary and secondary plant and animal succession producing and supporting a characteristic “ecological site.” An ecological site is a distinctive kind of land with specific physical characteristics that differs from other kinds of land in its ability to produce a distinctive kind and amount of vegetation. This vegetation, in turn, supports and is influenced by indigenous and endemic animal species. Because of natural disturbances, a number of successionally-connected plant communities on each ecological site form a “state” or assemblage of communities. An ecological site’s “reference state” is that assemblage of communities existing in North America at the time of European immigration and settlement. The full array of plant communities in a reference state is reconstructed from historical accounts and by studying present-day and remnant forest vegetation. Human management after European settlement may have substantially changed vegetation and soil biotic and abiotic features to a degree that reference state communities are no longer intact and, under a natural regime of disturbance, will never develop again. In these cases, an altered state is identified. Altered states are typically produced by soil quality degradation or introduction of invasive species.

Within the NRCS, ecological sites are used as a platform in developing forest management plans with land-owning clients. This platform is supported by written documentation in the form of: 1) resource quality criteria including requirements for maintaining minimum forest soil quality attributes, 2) soil interpretations such as potential hazard of rutting by equipment or wildfire damage to identify the risk of impairment to forest soil health, 3) forest management practice application specifications that consider soil interpretations and meet resource quality criteria, and 4) economic considerations to assure a sustainable and profitable level of management. When one of the four legs of the platform is overlooked or trivialized, forest soil health may be compromised in the long-term.

Although a planning mechanism is in place to address forest soil quality, there are challenges in maintaining “health” on a any given forest management unit: 1) identifying the key and local soil attributes and their minimum threshold conditions constituting acceptable health, 2) having field-ready and practical techniques to measure before-and-after conditions, and 3) assuring the economic feasibility for clients to maintain minimum soil quality thresholds.

Link to Presentation (pdf; 2MB)

Lyn Townsend - Lyn Townsend is an NRCS Forest Ecologist on the core team of the West National Technology Support Center in Portland, Oregon. Lyn has thirty-five years of experience with planning, consulting and instructing in forestry, including forest-soils correlation and interpretation, agroforestry, watershed management and riparian ecology. His experience includes short-term international exchanges on forestry, agroforestry, and conservation and riparian technology in Costa Rica, China, Denmark, Micronesia, Taiwan, Thailand, Malaysia, and Australia. International travel also included a long-term assignment with the military in Sinop, Turkey. Lyn received a BS in Forest Science from Colorado State University and a Master of Science in Forest Resources from the University of Idaho.