Forest strata-dependent effects of vegetation attributes and soil nutrients on decadal changes in aboveground net carbon stock in two temperate forests
Forest strata-dependent effects of vegetation attributes and soil nutrients on decadal changes in aboveground net carbon stock in two temperate forests
复制标题
植被属性和土壤养分对两种温带森林地上净碳储量年代际变化的森林层依赖性影响
DOI：
10.1016/j.catena.2020.104776
复制
发表时间：
2020
期刊：
影响因子：
6.2
通讯作者：
Jin Guangze
中科院分区：
文献类型：
--
作者：
Cai Huiying;Li Fengri;Jin Guangze
植被属性和土壤属性是森林生态系统功能的关键决定因素。然而，这些因子如何决定整个森林地层的地上净碳储量变化（净碳变化）仍然知之甚少，特别是对于温带森林。利用重复森林资源调查、功能性状和土壤养分数据，分析了植被属性（多样性、性状组成和森林结构）和土壤养分对林下树木净碳变化的影响。利用结构方程模型分析发现，两种森林类型的森林结构都是净碳变化的最大驱动因子，且净碳变化与林分上层密度和林分下层基面积呈正相关。多样性和性状组成对地上层净碳变化均无显著影响。而在下层，多样性通过生态位互补效应与净碳变化呈正相关。由于林下植被属性，林分密度对林下净碳变化有负的直接和间接影响。林下多样性和性状组成与林下净碳变化关系不显著，但增加了林下树木的多样性、性状组成和森林结构。土壤磷浓度对表层净碳变化有正影响，对下层有负影响。此外，土壤磷浓度增加了林下植被多样性，但对林下植被属性没有影响。结果表明，植被属性和土壤养分对上下层净碳变化有不同的影响。林下树木对资源的过滤作用影响了林下生态系统功能及其对土壤养分的响应。本研究通过对复杂天然林中林下树木的分离分析，更好地了解温带森林地上碳汇的生态机制。
Vegetation attributes and edaphic properties are pivotal determinants for forest ecosystem functioning. However, how these factors determine the aboveground net carbon stock change (net C change) across forest strata remains poorly understood, especially for temperate forests. Here, we used repeat forest inventories, functional trait and soil nutrient data from large permanent plots in two old-growth temperate forests in northeast China to evaluate the effects of vegetation attributes (diversity, trait composition and forest structure) and soil nutrients on the net C change of overstorey and understorey trees. Using structural equation modeling, we found that forest structure was the strongest driver of net C change across forest strata in both forest types, which was positively related to stand density in the overstorey, and basal area in the understorey stratum. Neither diversity nor trait composition had any significant effect on the net C change in the overstorey. However, in the understorey stratum, diversity was positively associated with the net C change through niche complementarity effects. Due to understorey vegetation attributes, overstorey stand density had negative direct and indirect effects on net C change in the understorey. Diversity and trait composition in the overstorey were not significantly related to net C change in the understorey, but overstorey diversity increased the diversity, trait composition and forest structure of understorey trees. The soil phosphorus concentration had positive effects on the net C change in the overstorey, but negative effects in the understorey stratum. In addition, soil phosphorus concentration increased overstorey diversity but had no effect on understorey vegetation attributes. Our results showed that vegetation attributes and soil nutrients had different effects on the net C change in the overstorey and understorey strata. Resource filtering by overstorey trees affected the ecosystem functioning of the understorey stratum as well as its responses to soil nutrients. By separately analyzing the overstorey and understorey trees in complex natural forests, this study provides a better insight into the ecological mechanisms that play key roles in the aboveground carbon sequestration of temperate forests.