Greater risk of hydraulic failure due to increased drought threatens pine plantations in Horqin Sandy Land of northern China
Greater risk of hydraulic failure due to increased drought threatens pine plantations in Horqin Sandy Land of northern China
复制标题
干旱加剧导致水力衰竭的风险加大，威胁着中国北方科尔沁沙地的松树种植园
DOI：
10.1016/j.foreco.2020.117980
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发表时间：
2020-04-01
影响因子：
3.7
通讯作者：
Hao, Guang-You
中科院分区：
文献类型：
--
作者：
Li, Ming-Yong;Fang, Li-Dong;Hao, Guang-You
近几十年来，我国北方水资源有限地区防护林普遍衰退和死亡，在气候变化的影响下，这一现象可能会更加严重;然而，我们对干旱如何影响树木的长期生长状况及其与水分相关的生理机制的认识仍然有限。在这里，使用相结合的树轮分析和测量与水相关的功能性状，我们调查了长期的径向生长模式和潜在的生理在樟子松变种。蒙古松（Mongolica）和油松（Pinus tabuliformis）造林与环境水分有效性变化的关系。特别是，我们研究了树木年轮生长对干旱和木质部水力学的两个物种在两个网站的HSL不同的气候制度之间的关联，研究气候变暖相关的干旱对树木性能的潜在影响，使用空间时间替代的方法。树轮分析显示，最近的增长下降，较低的恢复能力，干旱，更严重的树在两个松树品种在半干旱的网站相比，半湿润的网站水力限制的程度更大。在干旱地区，两种树种的年轮宽度指数与当年5 - 7月总降水量呈显著正相关，与同期平均气温呈显著负相关，而在湿润地区，这种相关性不显著。较低的茎导水率和较高程度的木质部栓塞在干燥的网站表明，这两种松树遭受更强的水力限制时，环境变得干燥。此外，樟子松具有显着更高的水力传导率始终表现出较高的断面积增量比油松在这两个网站。我们的研究结果表明，樟子松，目前最广泛使用的树木，以建立在中国北方荒漠化地区的防护林人工林，是更容易下降比油松气候变得更热，更干燥，虽然前者有一个更高的增长率比后者。研究结果为北方有限水分条件下松树的衰退和枯死提供了机理解释，并表明在未来气候条件发生变化的情况下，油松可能是替代樟子松作为研究区人工林主要树种的更好选择。
Widespread decline and mortality of shelterbelt forests in water-limited regions of northern China have been occurring over the past few decades and may become more severe under the influence of climate change; however, our understanding on how droughts affect tree performance in a long-term context and the underlying water-related physiological mechanisms are still limited. Here, using a combination of tree-ring analysis and measurement of water-related functional traits, we investigated patterns of long-term radial growth and the underlying physiology in Pinus sylvestris var. mongolica (Mongolian Pine) and Pinus tabuliformis (Chinese Pine) in relation to variation in environmental water availability in Horqin Sandy Land (HSL), i.e. a key area of land desertification control in northern China where the two species are commonly used for afforestation. Particularly, we studied the association between tree-ring growth responses to drought and xylem hydraulics of the two species at the two sites of HSL that differ in climate regimes, examining the potential impacts of climate warming-related aridification on tree performances using a space-for-time substitution approach. Tree-ring analyses revealed greater degrees of recent growth decline, lower resilience to drought, and more severe tree hydraulic limitations in both pine species at the semiarid site compared to the semi-humid site. Tree-ring width indices of both species in the drier site showed significant positive correlations with May-July total precipitation of the current year and negative correlations with mean temperature of the same period, whereas such correlations were not significant at the wetter site. Lower stem hydraulic conductivity and higher degrees of xylem embolism in the drier site suggest that both pine species suffer from stronger hydraulic limitation when the environment gets drier. Moreover, Mongolian pine with a significantly higher hydraulic conductivity consistently showed higher basal area increments than Chinese pine at both sites. Our results suggest that Mongolian pine, the currently most widely used trees to create shelterbelt plantations in desertified areas of northern China, is more susceptible to decline than Chinese pine as the climate becomes hotter and drier, although the former species has a higher growth rate than the latter one. Our investigation provides a mechanistic explanation for the commonly observed decline and dieback of pine trees in water-limited environments of northern China and suggests that Chinese pine may be a better choice to replace Mongolian pine as the main tree species in plantations of the study area with a changed climate regime in the future.