Soil Facts
Forest Soils
Healthy soil is an important component of the forest ecosystem. It is a strong foundation for trees and plants to grow on, a habitat for numerous insects, fungi, and algae, and a lab where old organic matter is recycled back into the ecosystem.
soil (i) The unconsolidated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants. (ii) The unconsolidated mineral or organic matter on the surface of the earth that has been subjected to and shows effects of genetic and environmental factors of: climate (including water and temperature effects), and macro- and microorganisms, conditioned by relief, acting on parent material over a period of time. A product-soil differs from the material from which it is derived in many physical, chemical, biological, and morphological properties and characteristics.
[Soil Science Glossary, Soil Science Society of America]
Trees depend on soil
for; stability, nutrients, and
water. Most nutrient cycling takes place in the top two feet of soil where
supplies of air, water and food allow microorganisms to thrive. These
include bacteria, fungi and algae. These microorganisms work in
conjunction with insects and burrowing animals to break down dead or dying
plant and animal life. In the process they release carbon dioxide into the
air and nutrients into the soil.
Healthy soil is a living body made up of inorganic material, decaying organic matter, water, air and billions of organisms. Some organisms form partnerships with tree roots helping them to extract nutrients from the soil. Others are important in breaking down organic matter and cycling nutrients, making them available to the next generation of plants and animals.
Soil plays an important role in forestry. Rain water running off trees gets trapped in the soil like a sponge where it is retained for trees and plants as a water source. This also serves to limit water run-off into streams and filters various minerals and impurities from the water before it hits streams and rivers. Plant life including trees is essential for maintaining the integrity of the soil. If plants are removed (deforestation due to fire) then the soil is more at risk for erosion.
Learn more about Soil in our Eco-Link, Soils or Sustainable Forestry
Links:
- U.S. National Soil Survey Center (a technical facility of the Natural Resources Conservation Service (formerly Soil Conservation Service). It is an agency of the US Department of Agriculture.)
- Soil Fact Sheet (from the Soil and Water Conservation Society)
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Soil erosion caused by unsustainable practices is a global problem. However, in well managed forests, roads and roadsides can be engineered to minimize erosion and sedimentation. Soil is most susceptible to erosion after the removal of plants surface litter and duff which protect it from wind and water. Roots hold the soil together and anchor it in place. If plants are removed temporarily (i.e. trees being harvested) and the surface duff and organic layers remain intact, there may be little or no erosion. Also tough Forest Practice Acts mandate buffer strips along the riparian zones bordering rivers and streams. Modern cut-to-length harvesting systems and cable logging systems can greatly minimize soil disturbance. One of the key components of sustainable forestry is to keep soil in place.
Soil Sustainability
Soils are a renewable resource, but our uses of soil are not sustainable if erosion or other disturbances exceed formation or recovery. It is possible to maintain or improve soil conditions on a site by maintaining or increasing organic matter, nutrients and soil organism diversity. A variety of practices can be used, some more intensive or economical than others, to accomplish these important objectives.
We need to remember a simple slogan about soil as we consider stewardship options:
- Keep it in place
- Keep it porous
- Keep it organically rich
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