Forest Investment Account (FIA) - Forest Science Program
FIA Project Y092157

    Structure and functional values of riparian buffer strips for sustaining floristic diversity in interior forested landscapes
 
Project lead: Baldwin, Lyn (Thompson Rivers University)
Contributing Authors: Baldwin, Lyn; Bradfield, Gary E.; Karakatsoulis, John; Petersen, Christine; Black, Scott
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
Description:
The project description remains the same as stated below:
The use of alternative silvicultural practices to protect ecological integrity and biodiversity is a critical component of forest management in British Columbia. Retention of trees along riparian corridors has been identified as an important management practice (Blinn & Kilgore 2001; Swanson & Franklin 1992). While this management practice was implemented largely to protect in-stream water quality and habitat, the importance of riparian buffer strips for terrestrial biota is being increasingly recognized (Cockle & Richardson 2003; Hibbs & Bower 2001; Pearson & Manuwal 2001). Riparian forests often contain disproportionately species rich plant communities compared to adjacent uplands, leading to the conclusion that these habitats are important for regional biodiversity (Naiman & Decamps 1997). Furthermore, retained aggregates of trees (riparian or upland) within harvested areas have been hypothesized to act as source areas for recolonization of surrounding harvested areas during stand regeneration (Franklin et al. 1997). The majority of work addressing the effectiveness of buffer strips in protecting terrestrial biota has focused on vertebrates (Cockle & Richardson 2003; Darveau et al. 1995; Vesely & McComb 2002) with riparian vegetation largely ignored (see however Hylander et al. 2005; Hylander et al. 2002; Stewart & Mallik 2006). The appropriate width of effective buffer strips is also widely debated and little is understood regarding the contribution of buffer strips to forest health including the reassembly of communities in the adjacent upland harvested areas.
Within riparian areas, ground layer vegetation plays critical roles in water retention, erosion control and nutrient cycling (see review in Naiman & Decamps 1997). The purpose of this proposal is to evaluate the importance of riparian buffer strips of different widths in sustaining ground layer vegetation, including plants with cultural significance for the Secwepemc community. Vegetation (defined here as the herbaceous vascular plants and bryophytes on forest floor, boulder, tree base, and decaying log substrates) diversity will be sampled to obtain quantitative data on species composition as well as functional group (e.g. N-fixers, substrate-specific bryophytes) and culturally significant plant representation as a gauge of the ecological value of buffer strips. Bryophytes and vascular plants are important to include as they often show differential response to ecosystem perturbation (Hakan & Jonsson 2001). As vascular plants are rooted in the soil, their response may be predicated more on soil chemistry and moisture, while bryophyte response is often dictated by substrate availability and microclimate (Hakan & Jonsson 2001). Recognition of the cultural significance of plants in this study will allow us to partner our research findings with Secwepemc cultural knowledge, as well as historical and ongoing use of plants and their ecologies, to better inform forest management. In addition to the strong focus on characterizing the physical and biological properties of buffer strips in the field, this research will have a strong analytical focus on developing and testing quantitative diversity indices to help in the operational planning and monitoring of buffer strips. While ground vegetation is often used as a potential indicator of ecosystem change (Fenton et al. 2003; Gehlhausen et al. 2000), differential responses may be expected from taxonomic and functional groups found within the ground layer. Our proposal makes an important contribution to an integrated understanding of the role of riparian buffer strips for sustaining biodiversity across multiple taxonomic and functional groups. Specifically, we will address the following questions:
(1) Within riparian habitats, does the presence and/or width of a riparian buffer strip affect the diversity and abundance of the ground layer vegetation?
(2) Within adjacent harvested areas, does the presence and/or width of a buffer strip affect the diversity and abundance of the ground layer vegetation.
(3) Are there specific attributes of buffer strips or the ground vegetation (either indicator species, functional groups or culturally significant species) that can be integrated into a diversity index which would accurately predict the ecological value of the riparian strip?
This project specifically targets small, high-elevation streams as these streams are most often afforded the least amount of regulatory protection and have been relatively neglected by researchers (Moore & Richardson 2003). In our proposed study area small streams at high elevations are common thus affecting a large proportion of the forest as the effects of stream microclimate may extend up to 50 m into the uplands (Brosofske et al. 1997).

Related projects:  FSP_Y081157FSP_Y103157

    Deliverables:
Executive summary (0.6Mb)

Updated August 16, 2010 

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