Coastal temperate rainforests span broad gradients in temperature, moisture and continentality. These systems extend from WA, southern OR to southeast AK, including coastal BC (e.g., Schoonmaker et al. 1997; see attachment for full citations). Foundational studies on old growth dynamics have been conducted in southeast AK (e.g., Alaback and Juday 1989), southern BC (e.g., Lertzman et al. 1996) and WA (e.g., Spies and Franklin 1991),.. However, there has been little coordination of data collection or analysis, and no formal assessment of old growth characteristics across the biome. Remeasurements of old growth stands in WA indicate that current definitions of old growth structure may not apply at environmental extremes (Acker et al. 2006). Standardized, comparative studies across this climatic and geographic gradient would contribute to comprehensive models of natural structure and function and to information about old growth characteristics for forest managers.
In addition to quantifying the structural complexity of old-growth coastal temperate rainforests, we also need to understand their temporal dynamics. The structure of our coastal old-growth forests changes over time as trees grow and die, become snags and are recruited to coarse woody debris, and as coarse woody debris decays and disappears. It is this life, death and decay that imparts a structural complexity to these forests that provides important habitat, nutrient cycling (e.g., carbon sequestration), and hydrological interception and storage, generally lacking in younger, less complex stands.
In 1992 and 1993 Project Partner Paul Alaback and BC collaborators (including Principal Investigator Andy MacKinnon) established a series of stand-level monitoring plots along BC's coast. This project will re-visit, re-locate and re-measure these plots in the Kitlope, Tahsish-Kwois and Tofino Creek watersheds, over two sampling seasons. The data from 1992/93, and the data from 2008/2009, will individually provide us with detailed spatial data on stand structure. A comparison of the 1992/93 structure and the 2008/09 structure will allow us an unprecedented opportunity to quantify changes in structure over time.
Structural complexity in vertical and horizontal space is a definitive feature of coastal temperate forest systems (e.g., Zenner 2000). This patterning within old growth forests of the biome (as per Franklin and Van Pelt 2004) develops through interactions of fine scale gap dynamics (e.g., Lertzman et al. 1996) and broader-scale dynamics imposed by exogenous disturbance (Larson and Franklin 2006); the resultant mosaic may be a unique, emergent property of the old growth developmental stage (Franklin et al. 2002; Larson and Franklin 2006). Measurement of these attributes in coastal BC forests will support calibration of existing models of old growth features. Re-measuring the 1992/93 plots will allow us to evaluate hypotheses regarding growth, mortality, species transitions, recruitment to canopy or coarse wood debris pool, and decay. Further, these measurements will refine our understanding of correlates with unique functional features of old growth (e.g., invertebrate complexes, lichen communities, spatial patterns of specific tree species, gap configurations) and provide a defensible, empirical basis for initiatives that seek to retain or restore old growth features in coastal BC forests.
Specifically, we will measure attributes to answer the following questions regarding old growth structure and function in coastal BC forests:
(1) What are the differences in structural and compositional complexity of stands on different sites and at different latitudes?
(a) How are species and individuals (trees) distributed among size classes (height and diameter)?
(b) How are species and individuals (trees) distributed spatially?
(c) How do species richness, diversity, dominance differ in total and among strata (canopy, subcanopy, shrub, herbaceous; bryophytes ...
West, Heather, Saunders, Sari; MacKinnon, J. Andrew; Davis, Todd. 2009. Stand dynamics over 15 years in old-growth forests in the Coast Forest Region. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2009MR025
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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