Spatial Variation in Dominant Height and Basal Area Development in a Coast Redwood Forest: Implications for Inventory and Modeling

We studied spatial autocorrelation in productivity across 110 ha of coast redwood (Sequoia sempervirens) forest in north coastal California. Height growth of dominant redwood trees, basal area (BA) growth, and volume growth were assessed in a grid of 234 permanent sample plots. Semi-variance analysis indicated that productivity was spatially autocorrelated yet variable at smaller spatial scales (i.e., between nearby sample plots). Dominant redwood height growth lacked spatial continuity beyond 200 m, indicating that estimates of site index from plots closer than 200 m would be spatially autocorrelated. BA development was spatially autocorrelated in plots up to 300 m apart within the study area characterized by heterogeneous topography and variable species composition. These findings suggest that estimates of redwood site index demand greater sampling intensity than sampling to index BA or volume productivity. Our analysis provides a framework for refining estimates of forest growth, yield, and carbon stocks in natural forests in accordance with divergent gradients of productivity.