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，以实验研究生态系统对林隙的响应以及地上和地下林隙之间的时空关系。假设只有同时考虑地上和地下的结构和资源，才能理解社区和生态系统对差距的反应机制。将进行一项实验，以确定在成熟和古老的针叶林中形成地下间隙所需的地上间隙的大小。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获得性和损失以及植被反应中。为了检验假设，研究小组将在两个林分发展阶段：成熟(林下重新启动)和老生长阶段，创造从小到大五种大小的林隙(移除0、2、8和16棵树和32棵树)。将进行地上和地下采样，以估计林隙的平均值，包括根生物量(分成乔木、灌木和草本植物部分)、根区以下的氮素淋溶、土壤温度和水分、光照水平测定、灌木和草本植物生物量、种子萌发和高级更新监测。在老林分中，将对地上和地下资源(加上净N矿化)和营养生物量进行更密集的采样，以不仅提供林隙平均值的估计，而且提供林隙内空间格局的估计。此外，还将在老林分中建立沟槽试验，以测试地上和地下资源对树木建立和生长的相对重要性，并开发植物对资源反应的预测模型。三个机构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理解和森林资源管理都具有重要意义。

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.