Climate/Growth Correlations of tree Species in the Indus Basin of the Karakorum Range, North Pakistan

Abstract

The climate/growth relationships of four gymnosperm tree species growing in seven catchments in the Indus Basin of the Karakorum range, North Pakistan, were evaluated for using two versions of tree-ring chronologies: “standard” and “residual” chronology. The growth of the trees was compared to instrumental climate records registered in Gilgit and to a climate data set of a 0.5° latitude-longitude grid. The effect of the previous year’s tree-ring widths on growth resulted in a higher correlation in the case of “standard” chronologies. A consistently significant response to climate was observed for all species at all sites. Such results highlight the potential for a multi-species approach for climate reconstructions. Of all the four species assessed, the strongest climate signal was seen in Pinus gerardiana. Winter and spring precipitation showed a pronounced positive correlation with tree growth while an inverse response to spring temperature was seen. Of the two climate parameters (temperature and precipitation) the strongest response was seen to rainfall. The gridded and the instrumental climatic data produced similar correlation patterns but the highest values were obtained with the “local” Gilgit data although some tree-ring sites are about 90 km apart from this meteorological station. Overall, the results demonstrate a high potential of the trees of the study region for reconstructing of past climate and past river flow.