TY - THES T1 - Tree-Ring Reconstruction of Western Spruce Budworm Outbreaks in the Rio Grande National Forest, Colorado T2 - School of Renewable Natural Resources Y1 - 1999 A1 - Ryerson, Daniel E. KW - colorado KW - dendrochronology KW - department of agriculture KW - forest service KW - national forest KW - outbreak KW - palmer drought severity index KW - RGNF KW - rio grande KW - tree ring KW - western spruce budworm AB -

 

Tree-ring records were used to reconstruct the spatial and temporal patterns of western spruce budworm (Choristoneura occidentalis Freeman) outbreaks in the Rio Grande National Forest (RGNF) of southern Colorado. Reconstructions at 11 host stands showed a synchronous pattern of outbreaks with a peak in the number of trees recording outbreaks over the entire RGNF on average every 24 years. These synchronous periods of outbreaks coincided with periods of increased moisture as indicated by an independently reconstructed summer Palmer Drought Severity Index, while relatively few trees recorded outbreaks during dry periods. The reconstruction on the RGNF does not support the hypothesis that human land use has significantly altered outbreak patterns. Tree response to outbreaks in the RGNF was different from prior studies as reductions in the growth were typically detectable only when growth was compared to that of nonhost tree species.

JF - School of Renewable Natural Resources PB - University of Arizona CY - Tucson VL - Master of Science ER -