Interannual climate variability has predominant effects on seedling survival in a temperate forest
Interannual climate variability has predominant effects on seedling survival in a temperate forest
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年际气候变化对温带森林幼苗的存活有主要影响
作者：
Xu Zhichao;Johnson Daniel J.;Zhu Kai;Lin Fei;Ye Ji;Yuan Zuoqiang;Mao Zikun;Fang Shuai;Hao Zhanqing;Wang Xugao
同种负密度依赖（CNDD）和生态位分配等机制已被提出来解释物种共存和群落多样性。然而，作为一个潜在的生态位划分的重要轴，年际气候变率在驱动当地社区动态的作用仍然在很大程度上未知。在这里，我们使用了一个15年的监测数据集，超过53，000幼苗在温带森林研究（1）什么是年际气候变化，生物相互作用和栖息地条件对幼苗生存的相对影响;（2）生物相互作用的影响如何随着年际气候变化和栖息地条件的变化而变化;以及（3）年际气候变率、生物相互作用和生境条件的影响是否因植物性状而异。年际气候变率占最大的变化幼苗存活在社区水平，其次是生物相互作用，和生境条件。在非生长季节增加积雪和降低最低温度对幼苗存活有积极影响。同种邻体密度效应随积雪量、有效积温、海拔和土壤资源梯度的增大而减弱，随紫外辐射、最大降水量、最低气温和土壤含水量的增大而增强。此外，年际气候变率与生物相互作用的相对重要性取决于物种特征组。具体而言，重力分散物种的生物相互作用在影响幼苗存活方面比其他性状组具有更大的效应大小。此外，重力分散的物种经历了更强的CNDD比风分散，可能是因为风分散的幼苗很少有成年同种附近。我们发现，年际气候变化与幼苗存活率关系最密切，但气候影响的大小在物种性状组之间存在差异。年际气候变率可能会抑制或加速密度相关的相互作用，并应在未来的研究中加以考虑，作为了解森林群落多样性的潜在直接和间接因素。
Mechanisms such as conspecific negative density dependence (CNDD) and niche partitioning have been proposed to explain species coexistence and community diversity. However, as a potentially important axis of niche partitioning, the role of interannual climate variability in driving local community dynamics remains largely unknown. Here we used a 15‐year monitoring data set of more than 53,000 seedlings in a temperate forest to examine (1) what are the relative effects of interannual climate variability, biotic interactions, and habitat conditions on seedling survival; (2) how the effects of biotic interactions change with interannual climate variability, and habitat conditions; and (3) whether the impacts of interannual climate variability, biotic interactions, and habitat conditions differ with plant traits. Interannual climate variability accounted for the most variation in seedling survival at the community level, followed by biotic interactions, and habitat conditions. Increased snowpack and decreased minimum temperature during the non‐growing season had positive effects on seedling survival. Effects of conspecific neighbor density were weakened in higher snowpack, effective accumulated temperature, elevation, and soil‐resource gradient, but were intensified with increased ultraviolet radiation, maximum precipitation, minimum temperature, and soil moisture. In addition, the relative importance of interannual climate variability versus biotic interactions differed depending on species‐trait groups. Specifically, biotic interactions for gravity‐dispersed species had a larger effect size in affecting seedling survival than other trait groups. Also, gravity‐dispersed species experienced a stronger CNDD than wind‐dispersed, probably because wind‐dispersed seedlings rarely had adult conspecifics nearby. We found that interannual climate variability was most strongly associated with seedling survival, but the magnitude of climatic effects varied among species‐trait groups. Interannual climate variability may act as an inhibitor or accelerator to density‐dependent interactions and should be accounted for in future studies, as both a potential direct and indirect factor in understanding the diversity of forest communities.