Response Of Larix Gmelinii Radial Growth To Climate Change For Different Slope Direction

This paper, in order to investigate how slope direction influence on the radical growth of Larix gmelinii in response to climate change, we establish Larix gmelinii tree ring width chronology in both north and south aspect in three sites along a latitude gradient in Great Khingan mountain areas. We analysis the change character of average temperature, average maximum temperature, average minimum temperature and precipitation in the three sites, as well as tree growth variation in different aspect. Using correlation analysis method and moving correlation analysis method, we compare the relationship between Larix gmelinii radial growth and climatic factors for different aspect. The primary results are:(1) From 1960 to 2008, the average temperature, maximum temperature, minimum temperature showed a significant warming trend in the three locations, but the change in precipitation is different. In Alongshan (north site), the annual average temperature, annual average maximum temperature, annual average minimum temperature and annual precipitation trend were 0.36℃·(10a)-1,0.52℃·(10a)-1,0.21 ℃·(10a)-1 and 10.68 mm·(10a)-1. respectively in Keyihe (middle site) the trends of the annual average temperature, annual average maximum temperature, annual average minimum temperature and annual precipitation trend were 0.43℃·(10a)-1,0.48℃·(10a)-1,0.35℃·(10a)-1 and -12mm·(10a)-1 respectively in Chaor (south site) the trends of the annual average temperature, annual average maximum temperature, annual average minimum temperature and annual precipitation trend were 0.37℃·(10a)-1,0.39℃·(10a)-1,0.46℃·(10a)-1 and -5.89 mm·(10a)-1 respectively. Temporally, temperature increase is most obvious during the period of 1985 to 1990. Annual total precipitation reveal a increasing trend in the north site, while showing a decreasing trend in the middle and south sites. The changes of precipitation in north and middle sites were significant, while the change in the south site has not reached significant levels.(2)Tree ring statistics feature reveal that Larix gmelinii is suitable for dendroclimatology studies. The statistic values of Larix gmelinii standard chronology in north slope of middle site are superior to other plots. The magnitude of the trend of Larix gmelinii tree ring width in the north slope decreased from north site to middle site and then increased from middle site to south site. The magnitude of the trend of Larix gmelinii tree ring width in the south slope decrease from north site to middle site and then inccreased from middle site to south site. In the north slope of the middle site, Larix gmelinii is the most sensitive to climate change. In the northern and southern sites, the temporal changes of tree ring width chronology of Larix gmelinii for differ aspect is similar, while in the middle site, the temporal changes of tree ring width chronology of Larix gmelinii for differ aspect is different. Tree ring width chronology of Larix gmelinii in south and north slope direction in the south site with the highest similarity followed by the northern site. In the middle site, tree ring width chronology of Larix gmelinii in the north and south slopes is high in class distance. Generally, latitude difference of tree ring width chronology of Larix gmelinii is greater than the aspect difference..(3) The results showed that larch Larix gmelinii growth is mainly influenced by temperature, and the relationship between precipitation and radical growth is weak. The radical growth of Larix gmelinii in Great Khingan region is sensitive to temperature of the winter season, but the response for different site and slope were different. Correlation analysis shows: from the north site to north slope of the middle site, the lowest temperature has significant impact on the radial growth of Larix gmelinii in Great Khingan, from southern slope of the the middlesite to the south site, the highest temperature has significant impact on radial growth. Moving correlation analysis shows:in north slope of the north site climatic signal relatively constant throughout the study interval, in other locations, the climatic signal of Larix gmelinii is not stable in the whole research period. Beside the northern slope of the north site, radial growth of Larix gmelinii in other locations reveal a divergence in growth response to temperature after 1990.