PARENT SESSION
Contributed Oral Session 79: Forest Ecology: Communities, Species Richness, and Coarse Woody Debris
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 518 A, Level 5, Palais des congrès de Montréal
Inter-annual variability and spatial coherence of stand productivity in the central Cascades of Oregon.
Woolley, Travis*,1, Harmon, Mark1, O'Connell, Kari1, 1 Oregon State University, Corvallis, OR
ABSTRACT- Understanding the inter-annual variability of aboveground net primary productivity (ANPP) at multiple spatial scales is important in estimating carbon dynamics over large scales and determining the response of ecosystem processes to global change. We estimated annual tree biomass production from tree cores sampled in permanent plots of three age classes along gradients of elevation and moisture at the H.J. Andrews Experimental Forest. The objectives of this analysis were to examine the spatial coherence of annual tree biomass production and determine how climate and other environmental factors affect productivity spatially and temporally. Multiple spatial scales (i.e. stand, watershed, landscape) were examined to determine how temporal behaviors are expressed. Pearson correlations were derived for all pair-wise combinations of plots. Principal Components Analysis was used to examine relationships within and across sites to determine which age classes are most correlated and which environmental gradient is most important in correlations of ANPP between plots. Within a young second-growth watershed, correlation between plots was high, however the degree of correlation depended on position along a gradient of heat load and potential annual direct incident radiation. Preliminary results suggest that correlation of annual production between plots across the landscape is not as high as previously assumed. Correlation of ANPP between mature and old-growth plots was the highest (r=0.78), while comparisons between old-growth and young, and mature and young showed a significant decrease in spatial coherence (r=0.56 and 0.53 respectively). There also appears to be temporal lags associated with the response of annual productivity to monthly climatic variables. These initial results suggest that when modeling ANPP in forests of the central Oregon Cascades, the degree of spatial coherence needs to be considered, and that landscape response to climatic variability may be dampened relative to individual stands.
Key words: forests, cascades, primary productivity, inter-annual variability