Collaborative Research: Above- and Belowground Response of Coniferous Ecosystems to Tree-Fall Gaps

华盛顿大学、耶鲁大学和俄勒冈州立大学将开展一项合作研究项目，对生态系统对树木落差的反应以及地上和地下落差的时空关系进行实验研究。假设只有考虑地上和地下的结构和资源，才能理解群落和生态系统对间隙的响应机制。将进行一项实验，以确定在成熟和原始针叶林中形成地下空隙所需的地上空隙大小。研究人员还将测量地上和地下的结构变化如何反映在资源的可用性和损失以及植物的反应中。为了检验这些假设，研究小组将在两个林分发育阶段（成熟（林下植被重新生长）和老树生长阶段）建立从小到大的五种尺寸（0、2、8、16和32棵树被移除）的树落间隙。将进行地上和地下采样，以提供间隙平均值的估计，并将包括根系生物量（分为乔木、灌木和草本成分）、生根区以下的N淋溶、土壤温度和湿度、光照水平测定、灌木和草本生物量、种子萌发和高级更新监测。在原生林中，将对地上和地下资源（加上净氮矿化）和植物生物量进行更密集的采样，不仅可以估计林隙平均值，还可以估计林隙内的空间格局。此外，还将在古生林建立沟槽试验，测试地上和地下资源对树木建立和生长的相对重要性，建立植物对资源响应的预测模型。三所院校的项目团队非常优秀。研究场地和设施都是一流的。研究结果对森林生态学的基本认识和森林资源管理具有重要意义。

A collaborative research project will be conducted by the University of Washington, Yale University, and Oregon State University for an experimental study of ecosystem responses to tree-fall gaps and spatial and temporal relationship between above- and belowground gaps. It is hypothesized that mechanisms of community and ecosystem responses to gaps can only be understood if both above- and belowground structures and resources are considered. An experiment to determine the size of aboveground gap needed to form a belowground gap in mature and old-growth coniferous forests will be imposed. The investigators will also measure how above-and belowground structural changes are reflected in resource availability and loss and in vegetative response. To examine the hypotheses, the team will create tree- fall gaps of ranging from small to large in five sizes (0, 2, 8 and 16 and 32 trees removed) in reach of two stand developmental stages: mature (understory reinitiation), and old growth. Above and belowground sampling will be conducted to provide an estimate of the mean of the gap and will consist of root biomass (separated into tree, shrub and herb components), N leaching below the rooting zone, and soil temperature and moisture, light level determinations, shrub and herb biomass, seed germination and monitoring of advanced regeneration. In the old-growth stands, above-and belowground resources (plus net N mineralization) and vegetative biomass will be sampled more intensively to provide not only an estimate of the gap mean but of the within-gap spatial patterns. In addition, trenching experiments will be established in the old-growth stands to test the relative importance of above- and belowground resources on tree establishment and growth and develop predictive models of plant response to resources. The three-institution project team is excellent. Research sites and facilities are first rate. Results should be important to both the fundamental understanding of forest ecology and to forest resource management.