Forest Investment Account (FIA) - Forest Science Program
FIA Project Y102065

    Effect of Stand-Level Retention on Carabid Beetles in Coastal B.C.
Project lead: William J. Beese (Western Forest Products Inc)
Author: Pearsall, Isobel A.
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
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 Group Level, Group Removal and Riparian Retention experimental sites as follows: Year 1: Goat Island Group Level, North Island Riparian Retention, Stillwater Riparian Retention, Year 2: QCI Group Level, North Island Group Removal.

This study focuses on responses of organisms to stand configurations 4-6 years post-harvest. Information from numerous previous studies will be incorporated into the final analysis, including the data for responses of carabids to type and level of retention in the Tsitika Group and Stillwater Dispersed VR sites (1 & 6 years’ post-harvest), as well as data for responses to group size at two other VRAM sites (Klanawa and Cluxewe/Pt.McNeill). Thus, by the end of this study, we will have information for a total of 9 VRAM sites. VRAM sites were established between 2000 and 2002 and have been installed with random allocation of treatments and controls, with all sites chosen to be as uniform as possible in timber type, site series and topographic features. They make for an ideal experimental platform for analysis of effects of different stand-level configurations on our established indicator species, and upon completion of this study, the replication of three large-scale Group Level VR sites will also allow us to develop species abundance response curves for retention level from 0 to 30%.

By the end of the study, we will have made a clear comparison of the effects of dispersed, group level, group size, group removal and riparian group retention as alternative harvesting methods on biodiversity of carabid beetles. We will also be to define a response curve for abundance of this indicator group with retention type and level, thus assisting managers in determining possible threshold levels suggesting possible ecological minima. Loss of ecological resilience could be apparent when new, disturbance specialist species enter and become part of the ecosystem, at the expense of the original old growth species, and when recovery of the original community is delayed or negated when, patches become incapable of supporting communities of forest specialists. It will be important to assess this over the long term. The utility of this project can be expanded to the landscape level, by integration into a full-scale species accounting system.

This study will complement other work that is currently being carried out using carabid beetles as ecological indicators (e.g. work to examine possible associations between carabids and environmental variables such as coarse woody debris, vegetation, stand age and ants by Duncan McColl, UNBC), studies underway at NRC to examine the role of coarse woody debris (CWD) as habitat for epigeic arthropods, as well as other programs under the AM umbrella (effects of VR on planted and natural regeneration, and the use of terrestrial gastropods, epiphytes, and amphibians as indicator species for monitoring biodiversity effects from VR harvesting).

The primary users of our findings will be forest professionals and technicians responsible for managing, developing policies and practices, planning, and design of forest harvesting in BC Coastal ecosystems. The target audience includes people employed by the BC government, First Nations, forest companies and private consulting firms. Our results will specifically address the design of cutblocks for retention of stand structural attributes to conserve biological diversity. Application of the results to company guidelines and field practices will be facilitated by the AM program (made up of a research and monitoring framework, working groups and a process to provide feedback to management from research findings). Western FP is the largest licensee in coastal BC; therefore, results are applied over a large tenure and influence other licensees.
Related projects:  FSP_Y091065


Technical summary (0.6Mb)
Presentation: Effect of Stand-Level Structures and Configurations on Carabid Beetles in Coastal B.C. VR sites (2.8Mb)

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Updated August 16, 2010 

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