LTER: Interaction of Multiple Disturbances with Climate in Alaskan Boreal Forests

Bonanza Creek长期生态研究项目的重点是提高我们对气候变化和干扰制度对北方森林的长期影响的理解。总体目标是确定对森林动态、生物地球化学和干扰的主要控制因素，以及这些因素在面对气候变化时如何相互作用。森林动力学主题涉及生物种群和群落在扰动后的演替变化，强调历史遗产、随机过程和物种效应在确定演替轨迹和轨迹对气候的敏感性方面的相对重要性。演替过程中碳循环的变化取决于森林动态和其他元素循环的变化，但也影响养分有效性和微环境，从而影响森林动态的演替变化。对干扰制度的区域和景观控制侧重于对干扰的时间、范围和严重程度负责的过程。我们的研究设计在三个演替序列（洪泛平原、南向高地、北向高地）的密集地点进行实验和观察，以记录驱动演替变化的过程。我们将通过研究两个大区域来为这些深入研究建立更大的背景，一个是阿拉斯加内陆相对均匀的地区，另一个是阿拉斯加从最温暖到最寒冷地区的气候梯度。通过综合，我们将解决三个重要的生态问题。(1)物种特征和多样性如何影响生态系统和景观中的生物地球化学和干扰机制？(2)如何将空间和时间尺度概念化为跨景观生态系统过程和模式联系的基础？(3)生态系统内运行的正反馈和负反馈如何影响生态系统对诸如气候和扰动机制变化等扰动的敏感性（即其可持续性）？

The Bonanza Creek Long-Term Ecological Research program focuses on improving our understanding of the long-term consequences of changing climate and disturbance regimes on boreal forests. The overall objective is to determine the major controls over forest dynamics, biogeochemistry, and disturbances and how these factors interact in the face of a changing climate. The forest dynamics theme addresses successional changes in biotic populations and communities following disturbance, emphasizing the relative importance of historical legacies, stochastic processes, and species effects in determining successional trajectories and the sensitivity of the trajectories to climate. Changes in the carbon cycle during succession hinge on changes in forest dynamics and other element cycles, but also influence nutrient availability and microenvironment and therefore successional changes in forest dynamics. Regional and landscape controls over disturbance regimes focus on processes that are responsible for the timing, extent, and severity of disturbances. Our research design uses experiments and observations at intensive sites in three successional sequences (floodplains, south-aspect uplands, north-aspect uplands) to document the processes that drive successional change. We will establish the larger context for these intensive studies by studying two large regions, a relatively uniform region in interior Alaska and along a climate gradient from the warmest to the coldest areas in Alaska. Through synthesis we will address three important ecological issues. (1) How do species characteristics and diversity influence biogeochemistry and disturbance regime within ecosystems and landscapes? (2) How can we conceptualize spatial and temporal scaling as the basis for linking processes and patterns from ecosystems across landscapes? (3) How do positive and negative feedbacks that operate within ecosystems influence the sensitivity of ecosystems (i.e., their sustainability) to perturbations, such as changes in climate and disturbance regime?