|Increased retention of trees in openings leads to increased edges compared to clearcuts. This study is designed to examine the effects of retained forest edge on the growth of regenerating trees in Coastal BC using two permanent plot data sets. This project specifically extends the similar project Y07-1001 in two areas: to a larger data set and includes significant data analysis. No funds were allocated to data analysis and only $12,000 was allocated from Y07-1001 for field work which is not sufficient to help us measure the following data sets: 1) Seven large scale (~100 ha) and three smaller scale (~40ha) experimental sites (all treatments randomly allocated) have been established across Western Forest Products landbase (Beese et al. (2005)). 2) Nineteen edge sites have been established across the former Weyerhaeuser BC Coastal Group’s landbase. The experimental sites were established on homogenous areas, have clearcut and uncut controls and up to 3 treatments comprised of different types and levels of variable retention (Beese et al. 2005). Categories are group retention, group size, dispersed retention, group removal and mixed retention. There are generally 3 treatments per site from low to higher levels of retention, and an uncut and a clearcut area, all randomly allocated. Within these experimental areas permanent long-term ‘sector plots’ (Iles and Smith 2006) have been established to examine the effects of forest edge on growth. In dispersed experiments, clearcuts and uncut areas 0.1ha ‘sector’ plots with a central angle of 36 degrees are established randomly. For group retention or group removal treatments four 9 degree sectors tied to a central 'pivot-point' are established with random angles in a minimum of 3 patches per treatment. At each experiment plots generally cover about 2ha. Each site permanently monitors 3000- 5000 planted trees, 2000+ tagged natural regeneration trees and 500-2500 retained trees measured on a 1,2,3,5,8 and 10 year cycle. Edge sites were generally set up before the experimental sites: their purpose was to explicitly examine trends in responses in planted trees and natural regeneration to forest edge environmental gradients. Measurement of these plots were not funded in Y07-1001. Plots were established in N, S, E and W directions. At least 3, and up to 6 rows of trees were planted from -5m to +50m across forest edges and measured on a 1,2,3,5,8 and 10 year cycle. Both sets of data are long-term (20 years+). As part of this project we request assistance in measuring a portion of these sites. Specifically to remeasure three experimental sites OP862222 (group size Klanawa), OP5599 (group size Port McNeill) and OP0185 (group removal Memekay) all planted to western hemlock; and 3 edge sites (Br112A, RatDog and Melrose 12- all Douglas-fir on Southern Vancouver Island with approximately 600 tree per site). Note that requested funds will only cover a portion of the actual cost for these sites; in-kind funding will make up the short-fall. We also request assistance with funding a full data analysis of information collected up to and including 2007-2008 from all the experimental and edge sites. This will include an analysis of planted and natural regeneration and retained tree growth responses across variable retention edges, linked to light, temperature and moisture gradients, which have also been collected from the sites. Data and analysis will help fuel the development of a regeneration phase of a spatially explicit microclimate-growth model called FORGE (Forest Growth Engine) previously developed. See the following link for a description of FORGE: https://www.for.gov.bc.ca/hfd/library/FIA/2005/FIA2005MR030-4.pdf. The analysis will examine natural and planted seedling and retained tree response: some sites are up to 8 years since planting. Results to date show that seedling and natural regeneration growth peaks at a distance from edges, patches or individual trees. A light model run alone does not fully explain this response but it is hypothesized that it may be additionally linked to a moisture model or some below ground effect. Data from natural regeneration will help drive a natural seed-in and advanced regeneration model. This model is coupled with a planted tree survival and growth model as part of FORGE. FORGE is a spatially explicit model that is lacking a regeneration phase. We propose to examine patterns of seed-in, mortality and growth with azimuthal orientation around retained patches. Regeneration survival and growth is currently linked to the light and moisture environment and distance from retained edges in the model. We would like to use funds to explore the patterns of growth more fully. Data on the growth response and regeneration patterns will be published in the Canadian Journal of Forest Research. There have been considerable changes in ownership recently so the funds will help us keep core assets intact. These sites cover over 1000 ha, with permanently tagged 30,000 planted seedlings and a similar number of retained and natural regeneration trees. Measurements will help maintain the sites and continue to make them useful for future science research. The size and scope of the experimental areas appears to be unique in BC. Forest management issues addressed: effects of variable retention on the survival and growth of the next crop across a wide range of sites and conditions for a variety of species. This has implications for timber supply and silvicultural prescriptions. |
Literature cited. Beese, W.J., B.G. Dunsworth, and N.J. Smith. 2005. Variable retention adaptive management experiments: testing new approaches for managing British Columbia’s coastal forests. Paper In: IUFRO: Balancing Ecosystem Values: innovative experiments for sustainable forestry, Portland, Oregon, August 2004. Iles, K. and N.J. Smith. 2006. A new type of plot that is particularly useful for sampling small clusters of objects. For. Sci., 52 (2):148-157.