Assessing the dendrochronological potential of Pinus occidentalis Swartz in the Cordillera Central of the Dominican Republic

Abstract

Opportunities for dendrochronology in the tropics are rare because few locations experience sesonality strong enough to induce annual (or even dependably cyclic) ring formation in trees. Consequently, any such opportunities that exist are valuable and identifying them is worth investing time and effort. West Indian pine (Pinus occidentalis Swartz) is endemic to the island of Hispaniola (l9°N, 71°W). It has prviously been shown not to produce useful rings in low-elevation (<2000 m) stands. We investigated its potential in small (4-11 tree) sample sets from four sites between 2000m and 3000m where seasonality of temperature and precipitation is more pronounced. Primary growth rings were distinct at all sites. False rings, diffuse rings, pinching rings and micro-rings were also present, and their number varied considerably by site. Quality of ring formation appeared to increase with both moisture stress (elevation, exposure, edaphic factors) and cold stress (elevation, exposure, cold-air drainage). We were able to cross-date saples (average interseries correlation= 0.44; average mean sensitivity= 0.44) from nine trees at the higheselevation site, and that chronology correlated significantly (r=–0.45, P<0.001) with monthly and sesonal maximum temperatures from a nearby meteorological station. This finding suggests a centuries-long reconstruction of temperature may be possible for this subtropical location. We conclude that, with careful site and tree selection, oversampling to allow exclusion of problematic specimens and greater use of coplete cross-sections rather than cores, P. occidentalis may allow dendrochronological reconstruction of climate, fire history and other environmental processes that operate on the island of Hispaniola.