BC’s Inland Rainforest – Conservation and Community

Conference Proceedings

Patterns and process in old-growth rainforests of southern British Columbia

André Arsenault1

This paper provides a synthesis of the dynamics and patterns of plant diversity in cedar-hemlock forests of interior and coastal British Columbia. We investigated the dynamics of rainforest ecosystems by comparing forest structure in different successional stages as well as by applying a variety of historical reconstruction techniques at the stand and landscape levels. We also examined the patterns of lichen and bryophyte diversity at three scales of ecosystem organization: 1) at a within-stand scale examining microdistributional ecology of species on various substrates; 2) at a meso-scale focussing on differences in species distribution and abundance in forests of different ages; and 3) at broader geographical scales assessing landscape and regional differences in species composition and developing predictive tools for the distribution of cyanolichens. Our work mainly took place in the ICHmw, ICHwk, and ICHvk subzones in several watersheds of the Southern Interior Forest Region and in the CWHvm subzone of Vancouver’s Northshore Mountains and Vancouver Island. Our studies on the distribution of cyanolichens on conifers also included information from various regions of the Northern Hemisphere. While inland and coastal rainforests were found historically to support similar amounts of old-growth, the frequency of very old trees (over 700 years old and up to 1500 years old) is much higher in coastal forests. A similar observation applies to the size of the largest trees, snags and logs. Important habitats for bryophytes and lichens included large rotten logs, and large leaning trees and snags, as well as trees growing within the nutrient dripzones of large trees having circum-neutral bark. At the stand level, species richness among bryophytes and lichens is consistently highest in old-growth forests, though the relationship between species diversity and stand age is complex and clearly varies with slope position. Species diversity is often much higher on toe positions in the inland rainforest which supports unique assemblages of epiphytic lichens, many of which do not occur on adjacent mid-slopes. These findings clearly show that ecosystem representation is an important element to consider during the designation of old-growth management areas to minimize the loss of biological diversity in managed landscapes.

Contact Information

1 Southern Interior Forest Region, Kamloops British Columbia. Email; Andre.arsenault@gov.bc.ca

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