Grizzly Bear Habitat

An Adaptive Management Approach for Integrating Grizzly Bear Habitat Requirements and Silvicultural Practices in Coastal B.C.

Contacts:

Tony Hamilton (Wildlife Branch - Victoria)
Ralph Winter - Silviculture
Hal Reveley - Silviculture Development Forester
Ted Nash - Silviculture - Vancouver F.R.
Donald S. McLennan principle worker for the project
Tom Johnson principle worker for the project

Background:

The project was initiated in 1992 to develop silvicultural systems that provide grizzly forage over the entire rotation of a managed stand, while, at the same time, producing high quality timber. As a result of the wide ecological variation on which the reduced stocking standards can be applied, silvicultural systems will be developed on a site- specific basis.

Objective:

The main objective of the project is to evaluate the effect of varying gap size and the numbers of trees per cluster within trial plantations on light conditions, and the species composition and productivity of forage species within the gaps created.

The second primary objective is to evaluate the influence of varying inter-cluster distances, and the numbers of trees per cluster on both timber quantity and quality within the plantation.

Specific objectives of the project are:

a) to evaluate the effect of varying gap size on;

i) light levels (photosynthetically-active radiation -PAR) within the gaps, both at the onset of the experiment, and as the plantation develops;

ii) the production, on a per hectare basis, of both the quantity and quality of grizzly bear forage;

iii) the species of forage plants that occur in the gaps, and how this changes with time.

b) to evaluate the influence of varying inter-cluster distances and the numbers of trees per cluster on both timber quantity and quality within the plantation, and, specifically, to;

i) assess the effects of different numbers of trees per cluster;

ii) assess the effects of different species mixtures within clusters; and,

iii) assess the effects of different pruning strategies.

Specific Objectives for 1993-1994 were;

1. 1. to document changes in light conditions and the response of forage species in naturally-occurring gaps in unmanaged stands, along a chronosequence of stands in 2 site associations.

Experimental Design:

In the context of this study, the management objective is to regenerate forest stands that have forage value over the entire rotation, while still producing high-quality timber. There is uncertainty associated with achieving this objective because a number of important factors that will determine the outcome are unknown. For example, it is not known how the proposed stocking levels will affect light conditions, and how these changes in light levels will affect the productivity of the different forage species. It is also not known how reduced stocking, whether clustered or widely-spaced, will affect timber quantity and quality, and how much stand tending will be required.

Given these uncertainties, the adaptive management approach to be taken is to initially, set up relatively small trials (4-10 ha) at a number of different spacing and cluster arrangements, and on a range of site associations. These initial blocks will be established at formal, informal and monitoring levels, and information will be gathered at intervals as the plantations are monitored. The trials will be monitored for forage production and growth and yield of crop trees to begin to identify the most promising methods. At the same time it is proposed that retrospective research be carried out to provide additional information from older, naturally-regenerated stands.

Conclusions based on this data will be used to alter or fine-tune the development of the most appropriate silvicultural systems. When original levels of uncertainty are reduced, then larger operational trials will be established with fewer treatments. It is expected that the overall objectives can only be achieved by monitoring a number of experimental sites over a complete rotation. Eventually, the most promising approaches for each of the site associations will be developed and become the operational standard.

The Working Plan outlines the approach to be taken, and describes the layout and experimental design of the trials. Please refer to this (McLennan and Johnson, 1993) document for more detailed information.

The generalized null hypotheses to be tested in the proposed trials are;
Ho1: that forage values in treatments and control blocks are the same
Ho2: that crop tree growth performance in treatments and control blocks are the same

As discussed in the Working Plan, replication for the formal trials will occur within site associations over a number of years as blocks become available. This distribution means that, in any given year of measurement, trials will be of different age, and will not be directly replicated within the same trial area. Because of this it is proposed that non- parametric statistical tests, such as the Kruskall-Wallis test for k>2 treatments, or the Wilcoxin-Mann-Whitney two-sample test, be used to compare treatments with controls.

Since informal trials will not be replicated from area to area, but will each represent a complete experiment, ANOVA can be used to test whether or not treated areas differ form control areas. In most cases the treatment effects will be random and quantitative, so that Duncan's multiple range test can be used to test the significance of means within treatments. Although such an approach will mean that results from one area cannot be extrapolated to the site association as a whole, the tests will provide meaningful results which will be useful in directing future research.

The formal and informal trials, and the monitoring areas described in this Working Plan represent the first stage in a long term, adaptive management approach. Information from all three levels of trial will be useful in determining an optimal approach to regenerating forest stands with high timber and forage values. Therefore, the adaptive management approach requires a long term commitment for all agencies involved to achieve the objectives of the project.

Monitoring:

Results will be forthcoming year-by-year as the work proceeds, and the information acquired form these studies can be incorporated into the trials as they continue to be established. In the long term these observations will provide information to assist in the design of experiments, especially the size and orientation of gaps within the trials. The research will also provide basic information on the autecology of grizzly bear forage species that will assist in developing ecologically-based approaches aimed at maintaining forage abundance within managed areas.

Retrospective Research (This work should be carried out during the berry production season (June-August)).

Assessing Gap Characteristics

Assessment of Forage Abundance

Light Measurements

Data Analysis

Time Frame:

Integration 1993-1994
Year 2 - Implementation of trials and retrospective research

Current Status:

Year Three

A range of activities were completed in 1994. Activities included trial layout, updating of trial records, development of a database, development of stocking tables for inclusion in the Grizzly Stocking guidelines, and analysis of TASS growth and yield projections.

Costs:

See Table 2 for the breakdown. Costs are presented for only those watersheds where it is known that visitation is required in 1993-1994. There will undoubtedly be additional watersheds which will be brought to our attention over the course of the year, and no provision has been made for these.

Total Projected Costs for 1993-1994 = $58,444.04

References:

Walters and Hilborn. 1978. Ecological optimization and adaptive management. Ann. Rev. Ecol. System. 9: 157-188.

McLennan, D.S. and T. Johnson. 1993. (WORKING PLAN) An Adaptive Management Approach For Integrating Grizzly Bear Habitat Requirements and Silvicultural Practices in Coastal B.C.: Working Plan. Oikos Ecological Consultants, Smithers, B.C. for Hamilton, Wildlife Branch, MoE, Victoria.

McLennan, D.S. and T. Johnson. 1993. (PROPOSAL) An Adaptive Management Approach for Integrating Grizzly Bear Habitat Requirements and Silvicultural Practices in Coastal B.C. (1993-1994) Year 2 - Implementation of Trials and Retrospective Research. Wildlife Branch, MoE, Victoria, B.C.

McLennan, D.S. and T. Johnson. 1994. (PROPOSAL) An Adaptive Management Approach for Integrating Grizzly Bear Habitat Requirements and Silvicultural Practices in Coastal B.C. (1994-1995) Year 3 - Implementation of Trials. Wildlife Branch, MoE, Victoria, B.C.

McLennan, D.S. and T. Johnson. 1994. An Adaptive Management Approach for Integrating Grizzly Bear Habitat Requirements and Silvicultural Practices in Coastal B.C. (1993-1994) - Canopy Gap Literature Review Retrospective Study Methodology. MoE, Wildlife Branch, Victoria, B.C.

McLennan, D.S. and T. Johnson. 1994. Guidelines for Integrating Grizzly Bear Habitat and Silviculture in Coastal B.C. - Stocking Standards. MoE, Wildlife Branch, Victoria, B.C.

B.C. Environment and Ministry of Forests. 1992. Interim Guidelines for Integrating Coastal Grizzly Bear Habitat and Silviculture in the Vancouver Forest Region. MoF and MoE, Victoria, B.C.

Johnson. 1995. Re: Summary Report of Activities For 1994/95 Grizzly Forage Trial Contract. MoE, Wildlife Branch, Victoria, B.C.

Johnson, T. 1995. Summary of Tass Projections As A Tool to Finalize Grizzly Bear Stocking Guidelines. Ministry of Environment, Wildlife Branch, Victoria, B.C.

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