Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing, China.
PLoS One. 2012;7(8):e42619. doi: 10.1371/journal.pone.0042619. Epub 2012 Aug 15.
Hemi-boreal forests, which make up the transition from temperate deciduous forests to boreal forests in southern Siberia, have experienced significant warming without any accompanying increase in precipitation during the last 80 years. This climatic change could have a profound impact on tree growth and on the stability of forest ecosystems in this region, but at present evidence for these impacts is lacking. In this study, we report a recent dramatic decline in the growth of hemi-boreal forests, based on ring width measurements from three dominant tree-species (Pinus sylvestris, Larix sibirica and Larix gmelinii), sampled from eight sites in the region. We found that regional tree growth has become increasingly limited by low soil water content in the pre- and early-growing season (from October of the previous year to July of the current year) over the past 80 years. A warming-induced reduction in soil water content has also increased the climate sensitivity of these three tree species. Beginning in the mid-1980s, a clear decline in growth is evident for both the pine forests and the larch forests, although there are increasing trends in the proxy of soil water use efficiencies. Our findings are consistent with those from other parts of the world and provide valuable insights into the regional carbon cycle and vegetation dynamics, and should be useful for devising adaptive forest management strategies.
在过去 80 年中，南西伯利亚从温带落叶林向北方森林过渡的森林经历了显著的变暖，而降水没有相应增加。这种气候变化可能对该地区的树木生长和森林生态系统的稳定性产生深远影响，但目前缺乏这些影响的证据。在这项研究中，我们根据从该地区八个地点采集的三种主要树种（欧洲赤松、西伯利亚落叶松和兴安落叶松）的年轮宽度测量结果，报告了最近半北方森林生长的急剧下降。我们发现，在过去 80 年中，由于前生长季（上一年 10 月至当年 7 月）和早期生长季土壤含水量低，区域树木生长受到的限制越来越大。土壤含水量的变暖诱导减少也增加了这三个树种的气候敏感性。自 20 世纪 80 年代中期以来，松林和落叶松林的生长明显下降，尽管土壤水分利用效率的代理指标呈上升趋势。我们的发现与世界其他地区的发现一致，为区域碳循环和植被动态提供了有价值的见解，对于制定适应性森林管理策略也很有用。
