Topic 2: The Protection of Soils

Introduction

Once established, soils remain dynamic systems that are always at risk of some form of erosion. This may occur naturally, but often is related to anthropogenic activities. The initiation of erosion is often related to some form of disturbance, with the removal of the vegetation cover being by far the most significant. Erosion is greatest where there is the greatest amount of energy, which in the context of soil erosion is on slopes.

In this module, we will first look at some of the processes occurring on slopes and how these interact with anthropogenic activities. The movement of rock materials and soil downslope is known as mass wasting, and is very important for forestry. The material may accumulate at the base of the slope, or may enter the fluvial system and be removed by streams and rivers. In some cases, the slope system and the fluvial system are coupled – material may be eroded from a gully wall on the upper part of a steep slope, directly entering the fluvial system, or a landslide or debris flow may transport debris directly into a stream channel.

We will also examine the processes that lead to soil degradation. These vary from one forest area to another, but in some parts of the world are very important. Forestry activities may be particularly important, and can actually lead to some of the erosion processes found in the slope and fluvial systems. On the other hand, forestry activities can also help conserve soil and can help stabilize areas that are unstable for a number of different reasons (such as eroding slopes or moving sand dunes).

Video Lectures

3.2.1 Mass movements

3.2.2 Soil degradation

3.2.3 Reducing soil degradation

3.2.4 Desertification 1: Dryland forests and desertification

3.2.5 Desertification 2: Causes of desertification

3.2.6 Desertification 3: China’s response

Resources

Textbook Reading:

• Chapter 6 of the course text:
  Innes, J., & Tikina, A. (Eds.). (2014). Sustainable forest management: From principles to practice. London: Earthscan Publications. ISBN: 1844077241

Further Reading:

• Soil-Net.com, an Educational Resource for Information on Soil Science. (n.d.). Soils: Advanced. Retrieved from https://www.soil-net.com/legacy/advanced/index.htm
  Soils are a complex subject, and there is a wealth of information available on-line. A useful starting point is at the above link.
• Nietch, C. (n.d.). Biogeochemistry. Retrieved from http://nerrs.noaa.gov/doc/siteprofile/acebasin/html/envicond/biogeo/bgtext.htm
  The biogeochemistry of the Ashepoo-Combahee-Edisto (ACE) Basin of South Carolina is provided at the above link.
• Bonn Perspectives. (2013, April 16). The value of soil [Video file]. Retrieved from https://www.youtube.com/watch?v=403sT9CGRl0
  Soil is of course essential not only for forests but also for agriculture. The two are closely related as the degradation of agricultural land can result in pressure to remove forests to make way for more agricultural land. A useful video that links these ideas can be found at the above link.
• British Columbia Ministry of Forests. (2001). Forest practices code of British Columbia: Soil conservation guidebook (2^nd ed.). ISBN: 0-7726-3991-4. Retrieved from: https://www.for.gov.bc.ca/tasb/legsregs/fpc/fpcguide/soil/Soilcol.pdf.

Other sources:

• Hope, G., Jordan, P., Winkler, R., Giles, T., Curran, M., Soneff, K., & Chapman, B. (2015). Post-wildfire natural hazards risk analysis in British Columbia (Land Management Handbook 69). Retrieved from: https://www.for.gov.bc.ca/hfd/pubs/Docs/Lmh/Lmh69.htm.
• Rollerson, T., Millard, T., Jones, C., Trainor, K., & Thomson, B. (2001). Predicting post-logging landslide activity using terrain attributes: Coast mountains, British Columbia (Forest Research Technical Report TR-011). Retrieve from: https://www.for.gov.bc.ca/rco/research/georeports/tr011.pdf.
• Weir, P. (2002). Snow avalanche: Management in forested terrain (Land Management Handbook 55). Retrieved from: https://www.for.gov.bc.ca/hfd/pubs/Docs/Lmh/Lmh55.htm.
• Wilford, D., J., Sakals, M.E., Grainger, W.W., Millard, T.H., & Giles, T.R. (2009). Managing forested watersheds for hydrogeomorphic risks on fans (Land Management Hanbook 61). Retrieved from: https://www.for.gov.bc.ca/hfd/pubs/Docs/Lmh/Lmh61.htm.
• Wilford, D.J., Sakals, M.E., & Innes, J.L. (2005). Forest management on fans: Hydrogeomorphic hazards and general prescriptions (Land Management Handbook 57). Retrieved from: https://www.for.gov.bc.ca/hfd/pubs/Docs/Lmh/Lmh57.htm.
• Wise, M.P., Moore, G.D., & VanDine, D.F. (2004). Landslide risk case studies in forest development planning and operations (Land Management Handbook 56). Retrieved from: https://www.for.gov.bc.ca/hfd/pubs/Docs/Lmh/Lmh56.htm.

Self-test