The values provided by streams & their riparian zones within forested landscapes continue to be of key concern in forest management (Lindenmayer & Franklin, 2002; Carey, 2006). Riparian forests provide a heterogeneous mosaic of habitats, with high levels of biodiversity, high productivity, & distinctive species compositions. They also serve as movement corridors for a number of species, including birds, bears & amphibians. In B.C., coastal forests within the coastal western hemlock zone likely contain the greatest diversity & abundance of wildlife habitat over any other ecological zone in the province.
Riparian forests make up a significant component of the productive forest in B.C. that is protected at some level from harvesting. Objectives of protection include provision of biodiversity & landscape connectivity, as well as protection of salmon & trout habitat. Guidelines with regards to methods for logging riparian sites were not provided until the 1980s, after much of the low density, structurally diverse riparian forest stands had been logged. Post-harvest stand development has often failed to recreate the complexity of the original stands, & thus efforts are sometimes made to employ silvicultural interventions to thin these stands.
It is proposed within Interfors Forest Stewardship Plan to commercially thin 2nd growth riparian areas to accelerate old growth characteristics. There has also been discussion on applying similar techniques in non-riparian forests for the same purpose as a recruitment method for old growth representation where a particular site-series-surrogate (Central Coast) is under-represented. Interfor is working collaboratively with Alan Banner in the development of second growth recovery curves, where it is hoped that the habitat contribution of second growth can be measured.
Interfor & Western Forest Products Inc. have been instrumental in the development of riparian restoration techniques designed to introduce old-growth attributes into riparian habitat. Between 1998 & 2002, these companies completed 12 operational riparian restoration field projects, totaling 348 ha of treated area along 70 km of fish habitat. The primary objective of these treatments, which included thinning overstocked conifer stands, releasing conifers suppressed by overstory deciduous trees, & replanting with preferred riparian tree species, was the rapid production of adequate large & coarse woody debris. Use of topping & habitat creation techniques produced 966 specialized biodiversity features such as topped & distressed trees, bat & small mammal, amphibian, & insect habitats. Effectiveness monitoring carried out in r sites in 2004 showed positive response in terms of radial growth, seedling establishment, enhanced fish habitat & reduction of windthrow. However, biodiversity responses were generally not apparent, as the time since treatment & monitoring was deemed too low.
Since a complete census of diversity is not feasible in stands, even those that have a relatively simple structure & composition, indicators or surrogate measures of diversity must be identified. Indicators must not only be ecologically meaningful, but must also be amenable to measurement by non-specialists & have wide applicability if management objectives for biodiversity are to be fulfilled. Epigaeic carabid beetles will be used as an indicator species, together with the associated invertebrate by-catch, to examine the effectiveness of riparian treatments carried out in West Vancouver Island.
The link between structural diversity of forest stands & their associated biodiversity has begun to receive increasing attention for invertebrates. Forest-floor invertebrates are a critical group to consider in riparian studies given their huge abundance & diversity, as well as their importance in forest ecosystem functioning e.g. in nutrient cycling, pollination & defoliation, & as a food base for other vertebrates & invertebrates (Schowalter 200
Pearsall, Isobel A.. 2009. Analysis of Riparian Restoration techniques on Biodiversity: Use of Invertebrates Indicator species to Determine Appropriate Restoration Options for Ecological Recovery of Riparian stands. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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