Spatial Relationship of Biomass and Species Distribution in an Old-Growth Pseudotsuga-Tsuga Forest
Abstract:Old-growth forests are known for their complex and variable structure and function. In a 12-ha plot (300 m × 400 m) of an old-growth Douglas-fir forest within the T. T. Munger Research Natural Area in southern Washington, we mapped and recorded live/dead condition, species, and diameter at breast height to address the following objectives: (1) to quantify the contribution of overstory species to various elements of aboveground biomass (AGB), density, and basal area, (2) to detect and delineate spatial patchiness of AGB using geostatisitcs, and (3) to explore spatial relationships between AGB patch patterns and forest structure and composition. Published biometric equations for the coniferous biome of the region were applied to compute AGB and its components of each individual stem. A program was developed to randomly locate 500 circular plots within the 12-ha plot that sampled the average biomass component of interest on a per hectare basis so that the discrete point patterns of trees were statistically transformed to continuous variables. The forest structure and composition of low, mediate, and high biomass patches were then analyzed. Biomass distribution of the six major species across the stand were clearly different and scale- dependent. The average patch size of the AGB based on semivariance analysis for Tsuga heterophylla, Abies amabilis, A. grandis, Pseudotsuga menziesii, Thuja plicata, and Taxus brevifolia were 57.3, 81.7, 37, 114.6, 38.7, and 51.8 m, respectively. High biomass patches were characterized by high proportions of T. heterophylla and T. plicata depending on spatial locations across the stand. Low AGB patches had high densities of A. amabilis and T. brevifolia. We presented several potential mechanisms for relating spatial distribution of species and biomass, including competition, invasion and extinction, disturbance, and stand dynamics. Clearly, future studies should be developed to examine the details of how each process alters the spatial patterns of tree species with sound experimental designs and long-term monitoring processes at multiple scales. FOR. SCI. 50(3):364–375.
Keywords: Douglas-fir; Spatial pattern analysis; WRCCRF; aboveground biomass (AGB); canopies; environmental management; forest; forest management; forest resources; forestry; forestry research; forestry science; natural resource management; natural resources; old-growth; semivariogram
Document Type: Regular Article
Affiliations: 1: Earth, Ecological, and Environmental Science University of Toledo Toledo OH 43606, Email: firstname.lastname@example.org 2: Department of Forest Resources, Belle W. Baruch Institute of Coastal Ecology and Forest Science Clemson University Georgetown SC 29442, Email: email@example.com 3: Department of Renewable Resources University of Alberta Edmonton Alberta Canada T6G 2E3 mark_, Email: firstname.lastname@example.org 4: Interagency Monitoring Program USDA Forest Service Portland OR 97208, Email: email@example.com 5: College of Forest Resources University of Washington Seattle WA 98195, Email: firstname.lastname@example.org 6: Sierra Nevada Research Center, Department of Environmental Horticulture University of California Davis CA 95616, Email: email@example.com 7: College of Forest Resources University of Washington Seattle WA 98195, Email: firstname.lastname@example.org 8: College of Forest Resources University of Washington Seattle WA 98195, Email: email@example.com 9: College of Forest Resources University of Washington Seattle WA 98195, Email: firstname.lastname@example.org
Publication date: June 1, 2004
- Forest Science is a peer-reviewed journal publishing fundamental and applied research that explores all aspects of natural and social sciences as they apply to the function and management of the forested ecosystems of the world. Topics include silviculture, forest management, biometrics, economics, entomology & pathology, fire & fuels management, forest ecology, genetics & tree improvement, geospatial technologies, harvesting & utilization, landscape ecology, operations research, forest policy, physiology, recreation, social sciences, soils & hydrology, and wildlife management.
Forest Science is published bimonthly in February, April, June, August, October, and December.
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