Forest Investment Account (FIA) - Forest Science Program
FIA Project Y073250

    Soil conditions and tree growth on rehabilitated and degraded sites: stewardship of British Columbia’s forest soils
Project lead: Bulmer, Chuck
Contributing Authors: Bulmer, Charles E.; Simpson, David G.; Krzic, Maja; Schmidt, Margaret G.; Blouin, Vikki M.; Zhao, Y.; Simard, Suzanne W.
Imprint: Vernon, BC : Research Branch, BC Ministry of Forests, 2007
Subject: Forest Investment Account (FIA), Soils, British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
Within FIA-FSP’s Sustainability Program, this project addresses research topic 1.2 'Soil biology, ecology, and productivity'. Specifically, the proposed work addresses topic area 3 by providing improved information on the effects of soil disturbance and rehabilitation on forest productivity through the use of innovative field tests describing soil physical conditions, and by making the new information available to forest managers and researchers throughout BC. Sustainable forest management relies on defining and monitoring ecosystem parameters to evaluate the response to practices such as access development and harvesting. Soil-based parameters, and particularly soil physical properties, are important in this regard because they underpin many important ecosystem processes, are relatively resistant to change in natural systems, yet can be strongly affected by forest management. Our ongoing project features a comprehensive approach using both field and laboratory investigations to explore new measures of soil physical conditions and their effect on soil productivity and ecological sustainability on a variety of site types in BC. Our objectives are to (a) identify soil physical conditions that are consistent with productive forest growth on disturbed and undisturbed soils in a variety of ecosystems, (b) develop and introduce management tools for the rapid evaluation of soil physical conditions in BC’s forests, and (c) describe, for a range of site and soil types in BC, a comprehensive picture of physical factors affecting the growth of tree roots and its variation throughout the growing season. For 2005 – 06, we will pursue the following related investigations addressing these objectives: 1. We will continue to evaluate existing field studies on tree growth and soil physical conditions for rehabilitated landings, by collecting updated tree growth information from a trial installed in 2000 at Dutton Creek, near Okanagan Falls in the Okanagan Shuswap Forest District. The Dutton Creek trial was set up to evaluate the effects of woodwaste addition to rehabilitated soils on landings, and their effect on the growth of lodgepole pine. Tree growth response will be compared to soil physical properties determined for samples collected in 2004, and in relation to field measurements determined previously. 2. Our ongoing controlled factorial studies of the effect of soil compaction and water content on the growth of lodgepole pine have provided important insight into thresholds of soil physical conditions that are suitable for productive growth of lodgepole pine seedlings. In 2005-06, we intend to continue these efforts by establishing a new trial in the raised beds that are already available at Kalamalka Forestry Centre (KFC). The new experiment will follow the same protocols as previous work, but will use a loam soil, and two species will be evaluated: lodgepole pine and white spruce. This work will complement previous investigations undertaken on lodgepole pine growing in clay loam, loamy sand, and silt soil. 3. We will continue to test portable field instruments for rapidly obtaining information on soil mechanical resistance, water content, and air-filled porosity. In 2004, we carried out preliminary evaluation of the air pycnometer for evaluating air-filled porosity, which is a crucial aspect of the least limiting water range and one we believe can be used to predict seedling response to soil compaction. So far, our testing of the air pycnometer has indicated that is well suited for use in soils that are relatively free of coarse fragments (<15%). In 2005-06, we intend to concentrate our use of this instrument, and of the theta probe and mini-penetrometer on sites with higher coarse fragment content (25-35 %) in southern BC. The sites we intend to use are the LTSP installations at Dairy Creek, O’Connor, and Black Pines in the IDF near Kamloops, as well as soil rehabilitation trials at Will Lake (near Falkland) and Miriam Creek (near Vernon). 4. We will continue to use lab evaluations of the relationships between soil strength and water content to determine the least limiting water range (LLWR) for forest soils representing a range of ecosystems in BC as a means to improve interpretations of soil compaction. A further group of soils, some from the previous study by Krzic et al (2003) . will be evaluated in laboratory compaction tests. Of particular interest to our new investigations, is the extent to which the laboratory – derived relationships reflect conditions measured in the field. A close fit between the two would provide a boost to our efforts to predict compaction effects in soils containing higher percentages of coarse fragments. 5. Our efforts to develop a comprehensive picture of how changing water content affects the rooting environment for undisturbed and disturbed forest soils in BC will be furthered by the proposed detailed studies for 2005-06 which are concentrated in the southern interior. In 2006-07, we expect to extend the information through continued efforts addressing these themes, and to complete initiative 5 by evaluating water content variation throughout the growing season for a variety of sites in other areas of BC. We have identified a graduate student to prepare a Ph.D. thesis, under the supervision of Dr. Maja Krzic at UBC, to integrate the information collected so far in this ongoing research effort, and provide a comprehensive description of the role of soil physical conditions affecting forests in diverse areas of British Columbia. The information will improve management of BC’s forest soils by increasing our knowledge of ecosystem processes controlling productivity for disturbed and undisturbed soils, and by developing and testing improved tools for evaluating compaction on BC’s forest soils, and its effects on ecosystem productivity.
Related projects:  FSP_Y051250FSP_Y062250


Final Techical Report (0.7Mb)
Presentation - Introduction to soil physical properties... (0.7Mb)
Presentation - Relationship between soil mechanical resistance... (1.9Mb)
Presentation - Soil Properties Affecting Compactability of Forest Soils... (0.7Mb)

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Updated August 16, 2010 

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