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Effect of Stand-Level Retention on Carabid Beetles in Coastal B.C.
Pearsall, Isobel A.
The Adaptive Management (AM) program developed by Weyerhaeuser in 1999 is being continued by Western Forest Products Inc. following the purchase of their tenure. The aim of this program is to examine the effectiveness of stand-level retention and landscape zoning for maintaining the forest attributes necessary to sustain biodiversity and essential ecosystem functions. Biological processes are difficult to measure directly, but the AM program has identified a range of indicator organisms and structures that might prove useful in assessing ecosystem health. Ideal indicators are individual species, groups of species or structures that perform critical ecosystem functions or are particularly sensitive to the attributes disturbed in logging. Over the past 7 years, we have conducted a number of large-scale field projects to examine the utility of ground beetles as biodiversity indicators (Pearsall, 2002, 2003, 2004, 2005, 2006, 2007). We have identified that carabid beetles are a highly sensitive indicator species, with significantly different communities in clearcut, immature and mature forests, including disturbance specialists, generalists, forest and old-growth specialists. We have shown that their responses are sensitive at small enough spatial and temporal scales such that they may be used to indicate edge conditions, and to assess how quickly sites recover and re-establish typical old-growth communities. Through pilot studies, we have been able to fine-tune our methodology to sample effectively using pitfall traps, & to give adequate power for appropriate statistical analyses. Ground beetles are abundant and diverse in most ecological systems and thus serve as an appropriate group with which to make inter-regional comparisons. They operate at small spatial scales, are small in size, have small scales of movement and lifecycles, and have high reproductive ability. They are good integrators of a substantial amount of ecological information about the biological communities to which they belong because they may be primary or secondary predators in forest soils (Day and Carthy 1988). They have been used as an indicator guild to quickly and cheaply assess the biotic sensitivity of a forest and are generally chosen much more frequently than most other groups of insects for use in surveys. Because they show different levels of habitat selectivity, carabid assemblages can be used to characterize disturbance in various habitats (Niemela et al.1992, and have been used as an indicator of soil diversity after disturbance caused by forest fire (Holliday 1991), clear cutting (e.g. Langor et al. 1991), scarification, pollutants, land reclamation (Day and Carthy 1988), management of primeval or old growth forests (Terrel-Nield 1990) and climate change (Elias 1991). In B.C., Lemieux and Lindgren (2004) examined ground beetle responses to patch retention harvesting in high elevation forests, and Lavallee 1999 & Craig 1995 have examined variation in carabid beetle assemblages in forests. Results of our past studies have been in accord with many of the studies cited above, demonstrating that carabids show different levels of habitat affinity and display clear responses to both age of site and fragmentation. In 2007, WFP fully funded our project which was done to evaluate the response of carabids to type and level of retention in one Group level (Tsitika) and one Dispersed (Stillwater) experimental VR site 6-years post-harvest. In 2008, with FSP funding, we expanded this study which has allowed us to make a larger-scale comparison of the effectiveness of other stand-level structures and configurations in maintaining biodiversity in coastal B.C. forests. In 2008 we worked in 3 more of the original Variable Retention Adaptive Management (VRAM) experiments that are the foundation of the AM program (see diagram attached last year), and will complete this study by working in 2 final VRAM sites in 2009. Overall, we will have worked in Gro ...
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Presentation: Effect of Stand-Level Structures and Configurations on Carabid Beetles in Coastal B.C. VR sites

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