基于森林动态样地的阔叶红松林生产力时空格局与维持机制研究

The broad-leaved Korean pine mixed forests, as the zonal forest vegetation in northeast China, are facing serious degradation problem due to over exploitation and destruction. Studying the spatial and temporal patterns and maintenance mechanisms of forest productivity is an important foundation for restoring the degraded temperate mixed forests. This project will be conducted based on existing Forest Dynamics Plots network established in this area, including 25 ha Changbai mountain plot, 20 ha Fenglin plot and 9 ha Liangshui plot in Lesser Khingan, and 22 satellite plots with area larger than 0.5 ha. Using long term, consistent monitoring data, we plan to study the coarse woody productivity (CWP) change, evaluate the relative contributions of different species and functional group on CWP by analyzing the status of tree growth, recruitment and mortality between different censuses interval, and determine the spatial distribution patterns and temporal change trends of CWP by comparing all inventory data at regional scale. In the three key large plots, nutrient, water and light related traits were sampled with consideration of intra-specific variations. Combining phylogenetic diversity and stand diversity calculated by applying light detection and ranging approach, we will use structural equation models to explore the relative predictive power of different dimensions of diversity indices (i.e. species richness, phylogenetic diversity and functional diversity) and stand structure diversity on CWP. Synthesizing the difference in diversity, CWP and stand structure across different successional stages, we will clarify the internal biological and external ecological factors in maintaining forest CWP at multiple scales. The results obtained from this project will be helpful for understanding the inherent law of long term stability of productivity in this forest, and providing potential routes of productivity promotion in future. In practice, this project could also provide valuable scientific references for forest ecosystem service maintenance and scientific protection and cultivation of natural forestry resources.

阔叶红松林是我国东北地带性森林植被，目前退化严重，揭示其生产力格局和维持机制是促进退化森林恢复的基础。本项目拟依托在该区域已建成的固定样地网络（样地总面积约108公顷），在对群落长期、连续监测的基础上，通过分析树木生长、更新和死亡状况，评估不同功能群对地上生产力的贡献，在区域尺度上揭示生产力的分布格局及其变化规律；在考虑功能性状种内变异性的基础上，在重点三个核心样地内测定与植物养分、水分和光照利用密切相关的性状，结合三维激光扫描仪所反映的林分结构多样性，量化植物多样性（物种丰富度、谱系和功能多样性）和林分结构多样性对群落生产力的作用及相对重要性。同时对比生产力、多样性和林分结构在不同演替阶段上的异同，在多时空尺度下维持森林生产力的内在生物学要素和外在生态条件，探讨阔叶红松林生产力长期稳定的内在规律及未来提升的可能途径，为更好地维持该区森林生态系统服务功能，科学保护和培育天然林提供科学依据。

森林是陆地生态系统的主体，在陆地碳循环中起着关键作用，因此在碳中和背景下，如何提高森林生产力，持续增加森林碳库储量以及提高森林碳汇功能，已成为各方关注的热点。东北东部森林是东北地区、乃至东北亚地区最为典型的温带植被类型，也是我国东北部地区山地森林生态系统的主体，代表性温带针阔叶混交林和阔叶林所具有的碳汇能力决定了我国东北林区碳汇大小，进而影响到全国森林碳汇量。项目依托在该区域已建成的固定样地网络，在对群落长期、连续监测的基础上，通过分析37.8公顷样地内近74,300棵个体5~10年的连续监测数据，估算该区域森林近5年地上生物量年均净固碳速率约为0.33 Mg ha−1, 与全球老龄林和亚马逊热带雨林持平，不同样地间表现出强烈的空间变异性，且无论在老龄林还是次生林，大径级个体对地上生物量及其动态的影响不断增强；揭示了邻体效应和生境变量对个体存活的相对重要性随生活史阶段和林型而变化，并且生境变量在两个林型的不同生活史阶段的个体存活中都扮演重要的角色；同种负密度制约的强度随生活史阶段的增加而逐渐降低，而系统发育负密度制约的强度随生活史阶段的增加而逐渐增强；发现了树木死亡而非生长是决定区域森林生物量动态的主导因素，发现了树木生长和死亡速率随林龄增长而降低，但随土壤肥力增加而升高；阐明了树木生长、更新和死亡三个过程的主要驱动力：高植被绿量促进树木生长、植物多样性促进森林树木更新和资源获取型树种主导的群落会增加死亡率；阐明外生菌根（EM）和丛枝菌根（AM）树种与土壤养分条件的关系存在差异，且AM树种主要影响群落多样性，而EM树种主要影响群落生物量，进而导致群落多样性和生物量随土壤肥力呈现相反的变化趋势。该项目研究成果可为阔叶红松林生产力长期稳定的内在规律及未来提升途径提供有益参考，为维持和提升该区域森林生态系统碳汇功能和科学保护和培育天然林提供数据支持和科学依据。