Forest Investment Account (FIA) - Forest Science Program
FIA Project Y082020

    Indicators of biodiversity within aspen stands of the Interior Douglas-fir zone
Project lead: Larsen, Karl (Thompson Rivers University)
Contributing Authors: Oaten, Dustin K.; Larsen, Karl W.
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
Assessments of biodiversity, including species richness and community assemblages, should be a major consideration in determining the different levels of forest harvesting that occur across landscapes composed of different forest types. Tolko Industries Ltd. is one of the forest companies in British Columbia using measures of biodiversity and species richness in their land management process. Much of this work is focused within their Tree Farm License (TFL) 49 located near Kelowna, British Columbia, Canada. Preliminary work, within the TFL has suggested that the Interior Douglas-fir (IDF) biogeoclimatic zone should be given a relatively high conservation priority due to a high degree of species diversity as compared to other forest types (Hebert 2005). To this end, current forest retention practices by the company have focused on maintaining this forest type. However, the IDF zone is far from being a homogenous forest type: most patches are dominated by Douglas-fir (Pseudotsuga menziesii), but a smaller amount may be composed primarily of trembling aspen (Populus tremuloides), or a mixture of these and other tree species. Understanding the relative importance of these different habitats within the IDF is one of the next crucial steps in the overall forest management process. The trembling aspen component of IDF forests is of particular interest as this stand type has been shown elsewhere to have relatively high biotic diversity, compared to other forest types (Griffiths-Kyle and Beier 2002). However, it is unclear as to how trembling aspen contributes to overall biodiversity within BC’s IDF stands. There is also concern that the aspen component within North American forests is being significantly reduced by human activities, poor seedbed conditions and increased herbivory from ungulates and cattle (White et al. 1998). Indeed, within the Tolko TFL, less than 5% of the IDF is considered to be aspen-dominated. Because of the rarity of these stands, and because they appear threatened by anthropogenic influence, it is important that we further our understanding of their contribution to biodiversity across the landscape. A full assessment of the biodiversity of any habitat type is an extremely large if not impossible undertaking (Pearson 1994). Because of logistics, and the need to initiate a short-term project with achievable goals, we selected an initial suite of wildlife indicator species using information on relative home range size and dispersal ability, as well as the relative ease at which the animals may be monitored. For these reasons, we have selected carabid beetles, small mammals and cavity-nesting birds. In addition, these three groups of wildlife also have been touted as good choices of indicator species because their systematics are well known, they are relatively easy to sample, and their presence often indicates an overall degree of higher diversity (Pearce and Venier 2005, Rainio and Niemela 2003, and Mikusinski et al. 2001).
During the 2005 and 2006 field seasons, we conducted surveys of the small mammal,carabid beetle, cavity-nesting bird and stand attribute communities at 12 study sites (4 replicate stands of each of Douglas-fir leading, aspen leading, and mixed-wood) within the IDFdk (Interior Douglas-fir, dry cool subzone) forests on Tolko’s tenured land base. Our general goals were and are two-fold: (1) to quantify the diversity patterns of the three indicator species across forest types and (2) to make recommendations towards the use of certain species as bioindicator species in a long-term biomonitoring project. Analysis of these data suggest that trembling aspen stands had consistently higher abundance and species-richness values for all taxa, compared to the Douglas-fir and mixed-wood stands. FSP funds have also enabled us to expand our assessment of the small mammal communities. Like most other studies examining small mammal communities, we had not incorporated shrews into our biotic assessments. Shrews are notoriously difficult to identify to species in the field, yet being insectivores/carnivores, they represent a very different tropic level compared to the microtine rodents and should in theory be factored into assessments of biodiversity and/or biomonitoring programs (Sheftel and Hanski 2002). We had enough incidental captures of shrews to know they are relatively abundant in some of our study sites, so we expanded our study to include these animals, by a combination of modified live-traps and DNA sampling. We have begun analyzing hair follicles removed in the field to confirm species identities in the lab, using genetic markers. This work was not be possible without additional FSP funds. This work is also being supported by Thompson Rivers University. During the ensuing second year of potential FSP funding (2007/2008), we will complete extension activities including presenting our results via conferences and technical papers. This will include a presentation of results at the North American Forest Ecology Workshop in June 2007. Because the research covered a broad spectrum of data we anticipate that several technical reports will be submitted. In addition, we will also submit reports to the Sustainable Forest Management network. Potential funds for 2007/2008 will allow us to complete extension activities related to this work.
Related projects:  FSP_Y071020


Cavity-Nesting Bird Communities (0.4Mb)

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Updated August 16, 2010 

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