Dendroclimatological study of subalpine Abies spectabilis forests in Dolpa of Northwestern Nepal

Abstract

limate and tree growth relationships give valuable information in Dendroclimatic research which describes the sensitivity of trees to the climate. Abies spectabilis is one of the potential species for dendroclimatological studies. It responds sensitively to the climate. This study aims to analyze the growth responses of A. spectabilis to local climatic parameters of the study site by using tree- ring chronology. This dendrochronological research was carried out at Toridwari community forest of Majhphal village area, Dolpo in July 2011.Three vertical transects were selected. In each transect a quadrat of 20 m × 20 m was sampled from the upper species limit of the Abies spectabilis at tree line. Quadrats in each transect were laid at about 50 m walking distance from each other. Altogether, nine quadrats were sampled between 3592 and 3728 m asl.102 sampled from 90 trees of Abies spectabilis was taken. The coring of trees was performed with the help of Sunto –increment corer. After the preparation of samples using different techniques, the widths of the cores were measured at 0.01 mm of precision with the help of LINTAB measuring system linked with TSAP – win software. A 235 - year tree – ring chronology of A. spectabilis dating back to 1777 was developed. A quantitative analysis of the relationship between tree growth and climate based on a correlation and response function showed that the radial growth of tree – rings was statistically significant and negatively correlated with mean maximum temperature for the month of May ( correlation coefficient 0.554 , P< 0.01), and March ( correlation coefficient 0.43, P< 0.05) of the current year. In addition to that, a significant and negative correlation was found with mean temperature of May (correlation coefficient 0.43, P<0.05). Precipitation does not show any significant relationship with tree ring the study area. This study showed relatively low mean sensitivity (< 0.2).

Key words: climate change, tree-ring, Dendroclimatology, tree-line