全球变化知识资源中心

Forests are sensitive to climate change at high altitude and high latitude. Dahurian larch (Larix gmelinii Rupr.) has experienced an unprecedented forest retreat northward during the last century. Whether the response of growth to climate has dissimilar patterns at different altitudes, and what the "altitudinal trends" of forest development will be in the future, remains unclear. We dendroclimatically investigated the impacts of climate change on the growth of larch forests along an altitudinal gradient. In total, 721 trees from 25 forest stands, representing an altitudinal range from 400 to 950 m a.s.l. in the Great Xing'an Mountains, northeast Cbina, were sampled and used to develop tree-ring width chronologies. The results suggest that warming caused a dedine in larch growth at low altitude, while tree growth increased at high altitude. The growth-climate relationships indicate that October-February temperatures were positively correlated with larch growth at low- and high-altitude sites, but negatively correlated at medium-altitude sites (ca. 600-700 m a.s.l.). April-May (early spring) temperatures and October-January precipitation had positive effects on growth in general (ca. 75% of all sites). The effects of summer temperature/precipitation on larch growth at high-altitude sites were opposite to that at low-altitude sites. This change of response from significantly positive/negative correlation to significantly negative/ positive correlation occurred gradually along the altitudinal gradient. The relationships varied significantly with altitude both in the case of temperature (R-2 = 0.425, P < 0.001) and precipitation (R-2 = 0.613, P < 0.001). The shift in response of larch forest to changes in summer temperature and precipitation occurred in the areas with a mean annual temperature of ca. -4 degrees C and ca. -5 degrees C, respectively; larch growth at temperatures lower or higher than these thresholds was limited by temperature and precipitation, respectively. (C) 2019 Elsevier B.V. All rights reserved.