Tree-Ring Talk

Earlywood and latewood tree-ring chronologies offer promise for reconstructing season- specific, and in some cases, dual-season climate variability. This was our motivation for developing a new network of 50 intra-annual chronologies for the southwestern U.S., where annual precipitation is split between the westerly influenced winter and summer monsoon climate regimes.

Montane grasslands are distributed across the Southwest, but there has been little quantitative study despite their biological and economic value. The study area is the montane forest-grassland ecotone within the Valles Caldera National Preserve (VCNP) northwest of Albuquerque, New Mexico, situated in the heart of the Jemez Mountains. We hypothesize that the fire history record of the ecotone should closely reflect the fire regimes in the montane grasslands throughout the study area and that this zone served as a pathway to encourage the spread of fire to other valles.

Minimum blue intensity measurements of resin-extracted Pinus sylvestris samples, are shown to provide a robust and reliable surrogate for maximum latewood density. Blue intensity data from fifteen trees, are reported relative to a standard blue-scale in a manner similar to grey-scale calibration in X-ray densitometry. The resulting time series are highly correlated with X-ray densitometry data generated from the same samples and preserve a high level of signal strength.