Documentation:Open Case Studies/SOIL/Soil Fauna on the Long-term Soil Productivity Sites in BC

Case specific learning outcomes

With the help of a series of guiding questions and the interaction with instructors, you will be able to:

1. Define forest soil productivity and the factors controlling it.
2. Determine how forest practices can affect soil biota and soil productivity.
3. Determine how changes in forest soil productivity can be monitored.
4. Characterize the attributes of a productive forest soil, and assess how forest practices may affect forest soil productivity

Background

The forest soils are characterized by an enormous diversity of animal species. Soil fauna play a variety of roles in soil development and the maintenance of soil fertility. Soil macrofauna are defined as organisms bigger than 2 mm in body and includes ants, beetles, spiders, centipedes, millipedes, and earthworms. Although generally less numerous than soil mesofauna, macrofauna can represent a significant proportion of the animal biomass in the soil and play an important role in soil ecosystem function. For example, millipedes and earthworms break up organic matter, increasing its surface area and thereby enhancing microbial activity and nutrient cycling. Soil macrofauna mix and redistribute mineral and organic material and microorganisms within the soil profile.

Soil mesofauna range from 0.1 to 2 mm wide and include mites, springtails, Protura, Diplura, Symphyla, and Enchytraeidae as well as smaller forms of spiders, pseudoscorpions, and insect larvae. Via grazing, they control bacterial and fungal biomass, thus liberating immobilized nutrients and stimulating further fungal and bacterial activity, as well as enhancing plant growth. Furthermore, soil mesofauna transport microbial propagules and spores into new substrates and contribute to the development of soil structure and humus formation through the deposition of fecal pellets.

Timber harvesting and site preparation can modify physical and chemical properties of the soil, affecting soil porosity, composition, and organic matter content; forest floor and mineral soil temperatures; and soil water content. The alteration of soil porosity through compaction and the loss of organic matter through removal or displacement can directly influence biological activity, reducing the diversity and density of soil fauna and altering the structure and function of the soil fauna community. In 1990, in conjunction with a similar research program in the United States, the BC Ministry of Forests established the Long-Term Soil Productivity (LTSP) study to determine the effects of three levels of organic matter removal and soil compaction on soil productivity over a full timber rotation period. Data in this study case were obtained on the Sub-Boreal Spruce installations of the LTSP in central British Columbia.

Week One

Learning Objectives

• Describe which factors control forest soil productivity, and the diversity of forest soil biota.

Student Tasks

1. Define forest soil productivity and the factors controlling it.

1. Review the diversity of forest soil biota.

Guiding Questions

1. How does soil productivity for forestry contrast with agriculture and urban situations?

1. If the concept of soil productivity requires the assessment of ‘crop’ production, what are the ‘crops’ produced by forest soils? Think about this from different viewpoints, e.g. a timber harvesting company, a company harvesting non-timber forest products such as floral greenery and edible, commercial mushrooms, a soil biologist, an environmental NGO, a First Nations community, a community sharing the same watershed and the BC government.
2. How you could detect forest soil productivity changes that might result from forest practices?
3. What are the soil biota? Where do they reside? Why are organic matter and soil compaction major issues in forest soil productivity?

Key References

1. The Soil Biology Primer, on-line version http://soils.usda.gov/sqi/concepts/soil_biology/biology.html
2. The Long-Term Soil Productivity Study in British Columbia. FRDA report 256. http://www.for.gov.bc.ca/hfd/pubs/docs/Frr/Frr256.pdf
3. Botanical Forest Products in British Columbia. An Overview. April 1995. http://www.for.gov.bc.ca/hfp/publications/00002/
4. Sanborn, P. 1996. Understanding soil productivity and site disturbance, the SBS Long-Term Soil Productivity Study. Forest Research Note #PG-07. B.C. Ministry of Forests, Prince George Forest Station, B.C., Canada. http://www.for.gov.bc.ca/rni/ (then ‘Search this site’, soil productivity, 7. pg07.pdf)

Week Two

Learning Objectives

Assess how forest practices can affect soil biota and soil biotic productivity.

Student Tasks

1. Review the LTSP study (see literature).
2. Review background information on the affect(s) of forest practices on soil biota and soil productivity.

Guiding Questions

1. In the short term, what happened to the soil fauna communities (component) at the SBS LTSP sites and why?
2. In the short term, what happened to litter decomposition (process) at the SBS LTSP sites and why?
3. What might happen as a result of compaction and organic matter removal to the soil fauna communities and litter decomposition over the long term and how will this affect forest soil productivity?

Key References

1. Jeff Battigelli and Shannon Berch. Soil Fauna in the Sub-Boreal Spruce (SBS) Installations of the Long-Term Soil Productivity (LTSP) Study of Central British Columbia: One-Year Results for Soil Mesofauna and Macrofauna. LTSPS Research Note 05 available at http://www.for.gov.bc.ca/hfd/pubs/Docs/Ltsps/Rrn005.htm
2. Kranabetter, J.M. and Chapman, B.K. 1999. Effects of forest soil compaction and organic matter removal on leaf litter decomposition in central British Columbia. Canadian Journal of Soil Science 79: 543-550.
3. Linden, D.R., P.F. Hendrix, D.C. Coleman, and P.C.J. van Vliet. 1994. Faunal indicators of soil quality. pp.91-106 In: J.W. Doran, D.C. Coleman, D.F. Bezdicek and B.A. Stewart (ed.) Defining soil quality for a sustainable environment. Proceedings of a symposium sponsored by Divisions S-3, S-6 and S-2 of the Soil Science Society of North America, Division A-5 of the American Society of Agronomy and the North Central Region Committee on Soil Organic Matter (NCR-59), November 1992, Minneapolis, MN. SSSA Spec. Publ. No. 35, Madison, WI.

Week Three

Learning Objective

Propose how changes in forest soil productivity can be monitored.

Student Tasks

1. List all of the soil biotic components and processes that could be assessed to determine changes in forest soil productivity; and evaluate if this approach is practical.
2. Propose and evaluate surrogate or proxy indicators.
3. Review provisions in Forest and Range Practices Act (FRPA) and Forest Planning and Practices Regulation (FRPP) for soil conservation, including green tree retention and coarse woody debris.
4. Propose indicators of soil productivity to assess whether FRPA and FRPP are effective in maintaining forest soil productivity.
5. Develop a soil quality framework for forest productivity focussed on soil biological indicators.

Guiding Questions

1. What are soil biotic components and processes realted to forest soil productivity? What are the practical limitations to monitoring forest soil productivity through a list of all soil biotica components and processes?
2. What surrogates or proxies could be assessed given time and budget limitations? How well does each proxy indicator represent the soil biotic components you listed above?
3. What indicators of soil productivity could be used to determine whether FRPA and FRPP are effective in maintaining forest soil productivity?

Key References

FOREST AND RANGE PRACTICES ACT http://www.for.gov.bc.ca/tasb/LEGSREGS/ (then click “Forest and Range Practices Act”)

(The following FPC Guidebooks are relevant to FRPA and are valuable sources of extra information):

• Soil Disturbance Hazard Ratings for Compaction, Displacement, and Surface Soil Erosion (PDF);
• Soil Disturbance Limits (PDF);
• Soil Rehabilitation (Webpage);
• Soil Disturbance Measurement (PDF);
• Silviculture Prescription Data Collection Field Handbook (PDF).

Week Four

Group presentations and synthesis

Each group will present results of their work on case 3 (please remember that your presentation should be maximum 20 minutes long) and along with the instructors compare and contrast the methods of diagnosis and interpretations of soil biological quality in the three case studies:

1. Forestry: Soil fauna on the long-term soil productivity (LTSP) sites in BC
2. Grazing: Soil mesofauna on grazed rangelands in BC
3. Agriculture: Biological indicators of soil quality at UBC Farm

The presentations will be evaluated on the basis of content, structure, and delivery (for specific details of evaluation criteria please refer to the course syllabus). One of the signs of successful presentation is how well the presentation engages other groups into discussion.