Forest Investment Account (FIA) - Forest Science Program
FIA Project Y073062

    Cumulative watershed effects of forestry practices on stream ecosystems
 
Project lead: Zhang, Yixin
Contributing Authors: Zhang, Yixin; Pinto, Xavier; Richardson, John S.
Imprint: Vancouver, BC : University of British Columbia, 2007
Subject: Forest Investment Account (FIA), Stream Ecology, British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
Description:
Watershed effects of forestry practices accumulate in forested landscapes where operations and management have occurred for long periods of time, which can result in impacts on forest biota and ecosystem processes. Since the potential negative and landscape-level cumulative watershed effects (CWEs) have not been well examined, studies of cumulative impacts of forestry practices on biodiversity and ecosystem processes remain a vital area of research for forest ecosystems. This project fits best with topic 3.1, but is directly relevant to topics 1.6, 1.1, and 1.3 in addition. CWEs of timber harvest include changes in sedimentation, water temperature, organic debris, and flow regimes. However, determining the significance of these effects on forest fluvial biodiversity requires taking into account biological communities and ecological functions with the key factors determining habitat quality. Thus, fluvial biodiversity relating with CWEs is an important indicator integrating to sustainable forest management. Many fluvial systems are characterized by a hierarchical dendritic structure that is not well captured by current metapopulation models. Since a large portion of the biodiversity in forested landscapes is associated with stream ecosystems, we propose that the metacommunity is an important concept for a comprehensive approach to the conservation of forest biodiversity. Metacommunity is a network of communities linked by dispersal, in which each community acts as a source of immigrants for other communities in a region or drainage. Habitat loss due to fragmentation caused by forest practices reduces the complexity and health of stream ecosystems. CWEs change physical habitats through a series of physical processes that may result in species extinction or community extinction at a local scale. If on-site natural recovery from forestry practices has occurred after stabilization of the disturbed habitats, metacommunity dynamics may play a key role in this process. Immigration among metacommunities may enhance the local community recovery through the linear landscape dispersal of aquatic larvae in streams and the two-dimensional landscape dispersal of adult insects over land. Thus, metacommunity models can be a new approach for forest biodiversity conservation. There are two primary questions that need to be addressed. Do the CWEs of forestry practices significantly change downstream physical habitats of headwater streams? Do the CWEs adversely influence benthic primary productivity and benthic communities through altering physico-chemical characteristics of the habitats? This study will articulate fundamental relationships between physical and ecological processes that are determined by cumulative watershed effects of forestry practices, and will provide baseline information for long-term sustainable forest management decision, which is related with FIA’s Strategic Goal 1: 'to improve knowledge-based science on support of sustainability’. Thus, this project is the best fit for Sustainability Program, Recommended Research Topic 3 – Sustainable Forest Management Indicators, Targets, and Monitoring Systems, and combines the FRPA values with watershed and riparian function.
Related projects:  FSP_Y051062FSP_Y062062
Contact: Zhang, Yixin, yz11@txstate.edu

    Deliverables:

Executive summary (13Kb)

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Updated August 16, 2010 

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