Coast Forest Region Old Growth Dynamics (OGD) Project


  1. What is the Coastal Old Growth Dynamics Project?

  2. The OGD Project is a study of the characteristics of old growth forest ecosystems of coastal BC. The project utilizes a network of permanent, stand-mapped plots within provincial protected areas to study structure, composition and function of these forests over time. The foundation of the study is a set of plots established in 1992 and 1993. We are remeasuring and expanding these plots and adding new plots to the study network. Data from the OGD network provide a comparative understanding of old growth across climatic conditions and site and disturbance types. The plots provide benchmark measures for evaluating impacts of additional stresses, such as harvesting, development, and climate change on, old growth forests. Data from the OGD project are housed at BC MFR and are available for use in additional, collaborative research projects. 

  3. Purpose

    Long-term ecological study allows for development of ecological theory and testing of that theory in time scales that are relevant within forest ecosystems. Coastal temperate rainforests, in particular, are characterized by long disturbance intervals with as little as 0.001% of forest area affected by stand-replacing events per year (Pearson 2003), estimated turnover times of forest gaps of between 300 and 1300 years (e.g., Lertzman et al. 1996), and dominant tree species that are relatively long-lived, i.e., >500 years. The implications of changes in management activities such as restoration protocols, silvicultural techniques, or rotation periods, for forest structure, timber volume, and non timber forest resources are elucidated by data collected across research networks over many decades. Understanding recovery from harvest or other disturbances may require monitoring over hundreds of years.

    Coastal temperate rainforests span broad gradients in temperature, moisture and continentality. These systems extend from southern Oregon (OR) and Washington (WA) to southeast Alaska (AK), including coastal British Columbia (Schoonmaker et al. 1997). However, there is no permanent, maintained network of old growth research plots within coastal BC to provide a coordinated effort in ongoing evaluation of old growth features. There has been little organization of data collection or analysis, and no formal assessment of old growth characteristics across the biome.

    We expect the revitalization and further development of a Coastal Old Growth Dynamics (OGD) plot network to provide a system of study sites to build upon research from BC (e.g., Arsenault 1995; Lertzman et al. 1996), the US Pacific Northwest (e.g., Spies and Franklin 1991) and Southeast AK (e.g., Alaback and Juday 1989). This collaborative project will provide a standardized characterization of old growth for development of ecological theory and scientifically-based management. The network will provide an opportunity to test and validate expectations of temporal dynamics derived through a chronosequence approach (e.g. Trofymow et al. 2003) and dendroecological studies (e.g., Daniels 2003). The physical infrastructure and analytical databases will provide a foundation on which other researchers can establish additional, integrated projects without undertaking this initial (establishment) investment.

    Current, broad-scale management initiatives in coastal BC include developing operational approaches for ecosystem-based management (Central and North Coast; also Haida Gwaii) (Price et al. 2009), exploring the framework of ecosystem resilience for managing with climate change (Campbell et al. 2009), and evaluating ecosystem recovery to old growth state after disturbances (e.g., Banner and LePage 2008; Gerzon 2009). These programmes require empirical understanding of structure-function relationships from site to landscape levels, with particular attention to associations between disturbance, and other driving processes, and forest attributes and function. The characterization of old growth ecosystems across the OGD network provides data on the variation in old-growth attributes across coastal variants of the Biogeoclimatic Ecosystem Classification (BEC) within BC. The data establish the potential to monitor stand structure and physical or ecological processes within unmanaged stands for comparison to harvested or otherwise disturbed areas, and with increasing stress imposed by climatic change.

    Specifically, the Old Growth Dynamics Project is designed to measure attributes to answer the following questions about coastal B.C.’s old growth forests:

    1. What are the relative roles of regional climate (i.e., latitude, maritime influence), site type (biophysical mosaic), and disturbance regime (type, frequency, intensity) in determining the structural and compositional features of old growth stands?
    2. What structural and compositional characteristics provide quantifiable, ecologically-based definitions of old growth across the biome?
    3. How do old growth stand structure, composition, and function change over time?
    4. What features of our old growth forests will be most susceptible to change with climate shifts?


    Literature Cited


    Alaback, P.B. and G.P. Juday. 1989. Structure and composition of low elevation old-growth forests in research natural areas of southeast Alaska. Natural Areas Journal 9: 27-39.

    Banner, A. and P. LePage. 2008. Long-term recovery of vegetation communities after harvesting in the coastal temperate rainforests of northern British Columbia. Canadian Journal of Forest Research. 38: 3098–3111.

    Campbell, E.M., S.C. Saunders, K.D. Coates, D.V. Meidinger, A. MacKinnon, G.A. O'Neill, D.J. MacKillop, S.C. DeLong, and D.G. Morgan. 2009. Ecological resilience and complexity: a theoretical framework for understanding and managing British Columbia’s forest ecosystems in a changing climate. B.C. Min. For. Range, For. Sci. Prog., Victoria, B.C. Tech. Rep. 055.

    Daniels, L.D. 2003. Western redcedar population dynamics in old-growth forests: contrasting ecological paradigms using tree rings. Forestry Chronicle 79: 517-530.

    Gerzon, M. 2009. Modelling the recovery of old-growth attributes in coastal western hemlock forests following management and natural disturbances. M.Sc. Thesis, University of British Columbia, Vancouver, B.C.

    Lertzman, K.P., G.D. Sutherland, A. Inselberg, and S.C. Saunders. 1996. Canopy gaps and the landscape mosaic in a coastal temperate rain forest. Ecology 77: 1254-1270.

    Pearson, A. 2003. Natural and logging disturbances in the temperate rain forests of the central coast, British Columbia, Report to the BC Ministry of Sustainable Resource Management, Victoria, B.C.

    Price, K., A. Roburn and A. MacKinnon. 2009. Ecosystem-based management in the Great Bear Rainforest. Forest Ecology and Management 258: 495-503.

    Schoonmaker, P.K., B. von Hagen, and E.C. Wolf. 1997. The Rainforests of Home: Profile of a North American Bioregion. Washington, DC: Island Press.

    Spies, T.A. and Franklin, J.F. 1991. The diversity and maintenance of old growth forests. Pp. 296-314 In R.C. Szaro and D.W. Johnston (eds.). Biodiversity in Managed Landscapes: Theory and Practice. Oxford University Press, New York.

    Trofymow J.A., Addison, J., Blackwell B.A., He, F., Preston, C.A., and Marshall, V. 2003. Attributes and indicators of old-growth and successional Douglas-fir forests on Vancouver Island.  Environmental Reviews. 11:S187-S204.


  4. Historical Plot Establishment (1992-93)

    Background and Historical Objectives of the Project

    Between 1992 and 1993, Paul Alaback, then of the USDA Forest Service (PNW Research Station, Juneau, AK), and Fred Nuszdorder, then Regional Ecologist for the BC Forest Service, Vancouver Forest Region, established a series of 0.25 ha permanent, stand-mapped plots. These were established in old growth stands that the principal investigators (PIs) expected (or hoped) were going to be protected by provincial legislation.

    These plots contributed to a coastal transect of plots started in Southeast Alaska, and became part of a project designed to examine variability in coastal temperate old growth rainforest across this latitudinal gradient. Data were collected to evaluate biomass, structure, and composition and to monitor changes in ecosystem structure and function with climate change.

    Alaback and Nuszorfer anticipated that the establishment of these permanent plots would promote interdisciplinary studies. Well-documented sites would allow other researchers to find and use the study plots without the inefficiency of having to document basic vegetation structure in addition to the particular focus of their study. Unfortunately, resources were not available to digitize the spatial layers or to complete summary analyses of the initial years’ data to the extent anticipated.

    There were five plots established and measured during 1992, the first year of the historical OGD project. (Figure 1; Table 1). Two floodplain terrace sites were established and measured in the Tahsish-Kwois river valley, in what is now Tahsish-Kwois Ecological Reserve or Tahish-Kwois Provincial Park (plot not yet relocated). Tahsish Plot1 was established on an active floodplain terrace at the time, dominated by Sitka spruce (Picea sitchensis) and red alder (Alnus rubra) in the overstorey and salmonberry (Rubus spectabilis) in the understorey shrub layer. Tahsish Plot2 was on an old terrace with spruce, devil’s club (Oplopanax horridus) and salmonberry. One plot was mapped on a floodplain site in what is now Carmanah-Walbran Provincial Park. The sixth plot established that year was an upland forest plot (Thuja plicata-Tsuga heterophylla-Abies amabilis) near Port Hardy in the (then) proposed location for Kwakiutl Ecological Reserve. This Ecological Reserve proposal was not approved and the plot presumed logged.

    In 1993, two plots in the Kitlope River Valley were added to the plot network to provide information on two key ecosystems, (A) Douglas-fir (Pseudotsuga menziesii) upland forest and; (B) floodplain Sitka spruce forest.

    Table 1.

    Site characteristics for plots newly established, or relocated and remeasured, through the Coast Forest Region Old Growth Dynamics (OGD) project.


  5. Re-establishment, Re-measurement, and Expansion of the Project 2007-2009

    We have been working with partners from other agencies (BC Parks, Parks Canada), First Nations (Haisla First Nation, Kitlope River Valley), universities (Simon Fraser), and with the PIs of the historical plots (Paul Alaback , Audrey Pearson) to refind and remeasure the plots established in 1992-3. Field crews have remeasured features from these older plots, expanded the plots in many cases, and added additional ecological measurements to the database.

    We have been evaluating potential sites to add to the network based on their utility for addressing questions of interest in ecological theory and application, the joint needs of our partners, resource availability, and site accessibility. Additional, existing, stand-mapped plots are available to provide comparative temporal and spatial data along the BC coast. For example, two plots established in 1995 by Trudy Chatwin at Rocky Point on southeastern Vancouver Island (Figure 1) will be remeasured to compare our data to information from these drier ecosystems. A stand-mapped plot initiated through the Smithsonian Institution’s Man and the Biosphere (SIMAB) Program by B. Beasley at Bamfield on the west coast of Vancouver Island (Figure 1) provides additional comparative data. We hope to remeasure these plots in cooperation with the PIs.

    In the long term, we hope to establish an upland plot in mesic (zonal, BEC) conditions for each of the coastal biogeoclimatic variants represented in the Coast Forest Region. During the initial stages of project revitalization, we are trying to refind and remeasure the historic plots and then to establish new plots where access, collaboration with other agencies, and time or funding allow. This ensures that the historical data are housed in standardized form and the data on temporal dynamics are acquired in a timely manner. This approach also allows us to build on the network within the constraints of available resources and develop research partnerships for the future remeasurements and projects.

    Some of the historical plots were established not to examine mesic conditions but to provide opportunities to characterize disturbance regimes of the coastal system (floodplain plots in Carmanah and Kitlope) and to examine unique -and possibly ecologically sensitive- systems. e.g., Douglas-fir at the northern extent of its range in the Kitlope (Douglas-fir) Upland plot. Thus, we also anticipate adding floodplain systems (within protected areas) to compare to those plots established historically and to develop a more comprehensive understanding of the effects of differing disturbance regimes on stand structure, function, and composition.



Locations and Characteristics of Plots within the OGD Network

  1. Distribution of plots within historical distribution of the coastal temperate rainforest along the west coast of North America (figure used with permission of Ecotrust).

Figure 1.

Location of the OGD stand-mapped plots within the historical distribution of the coastal temperate rainforest of western North America (Figure used with permission of Ecotrust).
Black bold type indicates plots established in 1992-3 that have been remeasured in 2007-9; black. nonbolded type indicates plots established in 1992-3 that have not been remeasured; black, italicized type indicates new plots to the OGD system (established 2007-9); grey type indicates historical plots established by researchers other that Alaback et al. (Bamfield, B. Beasley; Rocky Point; T. Chatwin) that can provide comparative, temporal, stand-mapped data.

Plot Specific Photos:

  1. Bamfield
  2. Carmanah
  3. Clayoquot
  4. Kitlope
  5. Pacific Rim
  6. Rocky Point
  7. Tahsish-Kwois

Field Methodology

  1. Plot layout
    1. Plot Layout and Stand Mapping

      The historic, stand-mapped plots were 0.25 ha (50 x 50 m) in size. Where consistency and extent of the ecosystem being sampled allowed, these plots were expanded to 1 ha (100 x 100 m). Figure 2. illustrates the nesting of the historic Carmanah Floodplain plot within the new, expanded plot. The 1 ha plots were gridded into 20 x 20 m squares (hereafter termed subplots) to complete the100 x 100 m grid (excepting the Kitlope Douglas-fir plot which could not be expanded from its original size). Each corner of a subplot was sighted in with a Criterion Laser Survey Station (2007) or TruPulse 360 Laser Rangefinder (2008 and 2009). We permanently marked the corners with aluminum angle iron stakes. The stakes were labelled with their (x,y) location and topped with rubber chair leg caps for safety. Posts on the outer edges of a 100 x 100 m plot were 80 cm (3') long and internal posts (marking subplots) are 53 cm (2') long.

      Figure 2.

      Design for the 1 ha, Carmanah Floodplain (CAF; 2007) 1 ha old growth plot incorporating the historical (1992) 0.25 ha plot. Understory vegetation and substrate plots were established within each of 20 x 20 m subplot (N=25), with hemispherical photos in the centre of these vegetation plots and in the opposite corners of each subplot (N=50).


    1. Understory Vegetation Sampling

      We systematically placed 2 m x 2 m quadrats in the centre of the lower left quarter (a 10 m x 10 m cell) of each 20m x 20m subplot; vegetation plot centre was determined using the laser survey station. For example, the understory vegetation plot for the first subplot [subplot for which the lower left corner is (0,0)] would be centred on point (5,5). The temporary pin flags used at the corners of understory vegetation plots during data collection were surveyed in using compass and tape. For reference to locations of understory vegetation plots and hemispherical photographs, we labelled the 10 x 10 m subplot quarters A, B, C, and D in a clockwise direction from the lower left (see Figure 2. above or here).

      Percent cover of vascular and nonvascular species within the 2 x 2 m plot were estimated for tree (A), shrub (B), herbaceous (C) and seedling/moss (D) layers (DEIF; BC MoE 1998). In addition to the sublayer totals noted by DEIF, we recorded the percent of the shrub layer cover that was coniferous. We also recorded species that occurred on (were rooted on) CWD, not just those established on the forest floor and described their substrate using the following classes: F- occurs only on Forest Floor; L- occurs only on Logs; FL-occurs on both Forest Floor and Logs (foliar cover).

    2. Understory Light Environment – Hemispherical Canopy Photos:

      During 2007 and 2008 field seasons, photos were taken to evaluate variability in light conditions across the stands (Carmanah <Fig. 3> and Kitlope). Canopy photographs and canopy cover class estimates were taken at the centre of each understory vegetation subplot (N=25) and at an additional 25 points located in the upper right (C) quarter of each 20mx 20m grid cell (total locations = 50; minimum distance between photos points = 14.14 m; I. Giesbrecht, pers. comm.). Locations for canopy photos were offset in the direction of the larger side of the plot if a tree bole was in proximity of plot centre as follows: (1) for trees ≤ 80 cm DBH, offset photo location by 60 cm; and (2) for trees ≥80 cm DBH, offset photo location by 100 cm. Distance and azimuth from plot centre to the photo were recorded for each of these cases. Photos were taken both above shrub height and below shrub height for evaluation of impacts of the shrub layer on growing conditions of the herbaceous understory and seedling regeneration (See Figure 4).

      Figure 3.

      Variablility in light conditions across stands. Carmanah Flood Plain Hemispherical Canopy Photos Shown.


      Figure 4.

      Examples of hemispherical canopy photos taken (A) above shrub height; and (B) below shrub height for a point in the Carmanah Floodplain (CAF) plot. Photos were taken at point (5,5).

      Follow the link below to view links to all photos:
      All Carmanah Floodplain Hemispherical Canopy Photos

      Light environment was assessed from the photos using Gap Light Analyzer (Frazer et al. 1999; Frazer et al. 2000). To ensure photos had ideal contrast between foliage and sky for analysis, auto exposure bracketing was used to expose three photos (-1/3, 0, and +1/3 exposure compensation, or less often -2/3, 0, +2/3) at each location. The slightly underexposed (-1/3) photos provide high contrast between foliage and sky, and the least foliage gets “washed out.” These photos are ideal for use in the Gap Light Analyzer software which classifies each pixel as either sky or foliage.

  1. Measurement of Forest Structure and Composition

    In the field, we measured the location of each tree (≥7.5 cm DBH), snag (≥7.5 cm DBH and ≥1.3 m height) and piece of coarse woody debris (CWD, ≥ 7.5 cm diameter and ≥ 1 m length). Locations were recorded as the distance (m) and azimuth () of a feature from a known subplot corner, using the Criterion or TruPulse (See Figure 5A., 5B.). For CWD, we determined the location of one end and then noted the azimuth of lay of the piece from that point along the ground; in Carmanah we initially tried a different protocol, recording the location of both ends of a piece. Generation of the logs digitally in our spatial maps was no easier using the two mapped ends than with one; we thus reverted to the mapping of the single, tagged end of a log.


    Figure 5.

    Mapping the location of structural features using the Criterion (Figure 3A, 2007) and the TruPulse laser rangefinder (Figure 3B, 2008-9)

    Trees and snags were tagged with uniquely-numbered, plastic tags at 1.3 m height from the point of germination. Tags were hung from ladder zap straps stapled onto the north side of the tree for upland plots - in Carmanah, tags were placed on the side of the trees facing away from hiking paths – and on the side facing away from the river for riparian/floodplain plots. Coarse woody debris was tagged at the end used to mark the piece location, i.e., the end to which an azimuth and distance were noted from the criterion location. A uniquely-numbered plastic tag was strung on galvanized 19 or 20 gauge wire that was wrapped and secured about the piece. (See figure 6)

    Figure 6.

    For trees and snags, we recorded species, DBH (See Figure 7) (S (DIAM1, 1.3, from tagged end for CWD), height, and information on morphology (e.g., a big fork or big sweep in the tree) or pathology (e.g., scar, mistletoe). We also recorded decay class (as per BC MoE 1998) and mode of mortality, if possible, for snags (e.g., snap, fungal) and decay class, height above ground, tilt of piece, and diameter of the second end (untagged end, DIAM2) for CWD (BC MoE 1998).

    Figure 7.

    Measure of DBH

  2. Soil Sampling

    One full (>75 cm) soil pit was dug and described outside but adjacent to each permanent plot in association with BEC sampling to characterize these ecosystems. Methodology for describing soils followed BC MoE (1998) i.e., LMH25 (DEIF).

    In addition to this full soil pit, humus form was characterized in mini pits (about 20 cm depth) at each understory vegetation plot1. Organic soil horizons and upper mineral soil horizons (e.g., Ah, Ae) were evaluated for characterization of humus form (e.g., Figure 8).

    Figure 8.

    Typical, shallow-soil profile for the Kitlope floodplain. Values are medians and ranges, unless otherwise noted, based on the sample of 24 subplots that do not occur in streams (I. Giesbrecht, SFU).

    1Data on humus form was collected by I. Giesbrecht during data collection for his M.R.M. work at Simon Fraser University. Humus form descriptions were not completed for the Clayoquot floodplain (CR) plot.

    Literature Cited

    BC Ministry of Environment. 1998. Field Manual for Describing Terrestrial Ecosystems. BC Minisry of Environmental, Lands, and Parks, and BC Ministry of Forests: Victoria, BC. Land Management Handbook 25.

    Frazer, G.W., C.D. Canham, and K.P. Lertzman. 1999. Gap Light Analyzer (GLA) Version 2.0: Imaging software to extract forest canopy structure and gap light transmission indices from true-colour hemispherical (fisheye) photographs. Simon Fraser University, Burnaby, British Columbia, and the Institute of Ecosystem Studies, Millbrook, New York.

    Frazer, G.W., C.D. Canham, and K.P. Lertzman. 2000. Gap Light Analyzer Version 2.0. Bulletin of the Ecological Society of America 81:191-197.


Digital Data Development - Current and Historical Spatial Layers

  1. Shapefile Creation from Tabular Survey Data

    Initial plot surveys to record the locations of trees, snags and coarse woody debris were completed in 1992 and 1993, with follow up surveys completed in 2007 - 2009. During the 1992 - 1993 historical survey, data was recorded in a relative XY grid format, originating from one known location. In the 2007 - 2009 follow up survey, distances and angles were measured from multiple known locations. These tabular recordings were used to spatially define the locations of, and create shapefiles for, the trees, snags and coarse woody debris using ArcGIS software.

    Click the link below to download a Microsoft Word document outlining the methodology and procedures followed to create spatial shapefiles from the tabular survey data.

    OldGrowthMethodology.Doc DOCUMENT INCOMPLETE

  2. Historical Sketch and Shapefile

    Figure 8.

    Carmanah Floodplain 1992-93 Historical sketch shown with digital spatial map.

  3. Carmanah Floodplain 2007. Trees, snags and Coarse Woody Debris.

Figure 9.

Carmanah Flood Plain 2007. Digital Spatial Map created from survey data.




Current Research Areas within the OGD Project

  1. Structural and compositional variability of old growth forests across the coastal temperate rainforest biome


    Extension Products to date:

    Saunders, S.C. and A. MacKinnon. 2006. Oral presentation at BC PARF, Victoria, BC.

    MacKinnon, A. and S.C. Saunders. Changes in structure and composition in an old-growth temperate rainforest stand in British Columbia, Canada. Poster presentation. IUFRO “Old Forests, New Management”, February 17-21 2008, Hobart, Tasmania.

    Saunders, S.C., A. MacKinnon, P. Alaback, H. West, and M. Meneghetti. 2008. Dynamics of structure and composition in an old growth temperate rainforest stand, southwestern British Columbia. Poster presentation, US-IALE, Madison, WI, April 2008.

    MacKinnon, A. S.C. Saunders, H. West. 2008. Developing a permanent plot network for long term, spatial evaluation of old-growth dynamics in the coastal temperate rainforest. Oral presentation (Research Snapper) at BC PARF, Dec. 2008; UNBC, Prince George, BC.

  3. The relative roles of Disturbance Regime, Climatic Conditions, and Site Heterogeneity on Vegetation Mosaic

    Floodplains are highly spatially and temporally dynamic systems within the coastal temperate forest landscape. Variation in site conditions, disturbance regimes, and climate contribute to development of unique vegetation mosaics (Balian and Naiman. 2005; Larson and Franklin 2006). We expect that multi-scale characterization of these ecosystems will contribute to management initiatives such as representation planning for riparian management, ecosystem-based management (EBM), restoration activities, and evaluation of terrestrial carbon budgets. We used data from two of the spruce floodplain stands within the plot network (Carmanah, CAF; Kitlope, KIF) to begin asking the following questions.

    • What roles do site type, disturbance regime, and subregional (latitudinal) climatic differences play in driving patterns of (and differences in): (a) species composition and structure of overstory (b) species composition and structure of downed wood?

    • How and why would temporal differences (over 15 yrs) in structure and composition differ between these locations?

    • How does understanding of these influences on composition and structure change with measurement scale?

    These two floodplains were chosen as pilot study units as they represent extremes of latitudinal range within our current plot network and provide contrasting site types and disturbance conditions.

    Extension Products to date:

    West, H. S.C. Saunders, A. MacKinnon, and T. Davis. 2008. Comparing structure and composition of two old-growth coastal floodplain stands. 2008. Poster presentation to BC PARF, Prince George, BC, Dec. 2008.

  4. Comparative understory communities of floodplains across Biogeoclimatic variants

    Examining the understory communities in these floodplain systems helps us to differentiate among the effects of climate, site, and disturbance on these ecosystems [see (2) above]. We are interested in commonalities in species across floodplain units, species unique to one disturbance regime or climatic regime, and dynamics of these communities. The Carmanah, Kitlope, Tahsish-Kwois, and Clayoquot locations all have floodplain plots.

    Figure 10.

    Percent cover of Carmanah floodplain vegetation for four strata: Tree, Shrub, Herb, and Bryophyte. Each stratum is further divided to show the three most frequent species (i.e. present in the most vegetation subplots) as well as the combined contribution of other species. These histograms are arranged in a grid to allow for examination of spatial patterns. In the shrub stratum, note the prevalence of RUBUSPE (salmonberry) across much of the site in contrast with the concentration of RIBEBRA (stink currant) in the lower-right quadrant (K. Stark).

    Table 2.

    Less frequent (i.e. occurring in only 1 or 2 plots) and less abundant (i.e. mean cover <1%) species (hereafter referred to as “rare”) at the Carmanah and Kitlope Floodplain plots. Species unique to Carmanah are yellow, species unique to Kitlope are blue, and shared species are green. Rare species tend to be unique in the shrub and herb strata, whereas rare species are both unique and shared in the bryophyte stratum.

  5. Effects of within-stand variation in old growth forest light environment on understory vegetation
  6. – current project of MRM (SFU) student Ian Giesbrecht

    My research examines spatial heterogeneity of canopy structure, light transmission, and understory vegetation in coastal old-growth forests of British Columbia, with emphasis on vegetation indicators of potential management importance. Fine scale disturbance and development of forest stands creates spatial heterogeneity of overstory structure and light transmission that may influence the structure and composition of understory plant communities (Franklin et al. 2002). Halpern and Spies (1995) hypothesized that “a shifting mosaic” of resources may explain why late seral forests have greater plant species diversity, and significantly greater abundance of some (‘late-seral associated’) species, than most younger stages of stand development. When applied to old-growth, this hypothesis predicts that variation of understory plant communities is organized along environmental gradients within stands. My research examines this and related hypotheses by studying variation of understory vegetation along gradients of light transmission, overstory structure, and substrate characteristics. Specifically, my research describes within-stand patterns of light transmission and understory vegetation in a range of coastal forest types, examines overstory controls on understory light availability, and assesses variation of understory vegetation in relation to light transmission and substrate characteristics (I. Giesbrecht, 2009). For further information on this research, please contact Ian G. at

Literature Cited

Franklin, J.F. 2002. Franklin, J.F., T.A. Spies, R. Van Pelt, A.B. Carey, D.A. Thornburgh, D.R. Berg, D.B. LindeLnmayer, M.E. Harmon, W.S. Keeton, D.C. Shaw, K. Bible, and J. Chen. 2002. Disturbance and structural development of natural forest ecosystems with silvicultural implications using Douglas-fir forests as an example. Forest Ecology and Management 155: 399-423.

Halpern, C. B., and T. A. Spies. 1995. Plant species diversity in natural and managed forests of the Pacific Northwest. Ecological Applications 5:913-934.

Extension Products to date:

Giesbrecht, I. and K. P. Lertzman. 2008. Fine scale variation of understory light and vegetation in two contrasting Sitka spruce (Picea sitchensis) floodplain forests of coastal British Columbia. Poster Presentation. BC-PARF, Dec. 2008. UNBC, Prince George, BC.

Figure 11.

Map of estimated understory light values and canopy cover class at Sandhill Creek (Pacific Rim Upland OGD plot). Light values between sample locations were estimated and mapped using a tension spline interpolation in ArcGIS.


Giesbrecht, I. MRM Thesis Working Title: “Fine scale variation of understory light and vegetation in coastal temperate rainforests of British Columbia” Simon Fraser University, School of Resource and Environmental Management – In Process

Figure 12.

Frequency distribution of understory light values (above shrub layer) at Sandhill Creek (Pacific Rim Upland plot), grouped by canopy cover class (n=50) (I. Giesbrecht)

Figure 13.

Scatterplot of mean light transmission versus proportion canopy gap, for Sandhill Creek (Pacific Rim Upland), Carmanah Floodplain and the Kitlope Floodplain plots (I. Giesbrecht).


Research Partners and Acknowledgements

  • Haisla First Nation for welcoming us to the Kitlope River Valley

  • Kitamaat Village Council

    • Logistics, boat support, base camp

  • BC Parks
    • Permitting, liaising with other co-operators, Logistics

  • Parks Canada
    • Permitting, research collaboration, logistics

  • Paul Alaback of University of Montana (then of USDA Forest Service), and field crews in 1992/93; Trudy Chatwin (BC MoE) and Audrey Pearson (Consultant)

    • PIs for historical plot establishment, field support

  • Dr. Ken Lertzman, School of Resource and Environmental Management, Simon Fraser University

    • Scientific project development, analytical support, graduate student supervision

  • BC MFR field crews 2007, 2008, 2009

    • Including: Rachel Field, Leah Ballin, Molly Hudson, Jane Pendray, Liz Poulsom, Sonya Powell, Kaeli Stark, Nicolette Watson, Rachel White.

  • GIS analysts and staff of ILMB, BC MFR, and Coastal Resource Mapping, Ltd. in Nanaimo

  • Clayoquot Biosphere Trust

    • Logistics, cabin use at Clayoquot Lk.


Contact for Further Information