Nave Lucas E, Gough Christopher M, Clay Cameron, Santos Fernanda, Atkins Jeff W, Benjamins-Carey Sonja E, Bohrer Gil, Castillo Buck T, Fahey Robert T, Hardiman Brady S, Hofmeister Kathryn L, Ivanov Valeriy Y, Kalejs Jennifer, Matheny Ashley M, Menna Angela C, Nadelhoffer Knute J, Propson Brooke E, Schubel Adam T, Tallant Jason M
College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan, USA.
Department of Biology, Virginia Commonwealth University, Richmond, Virginia, USA.
Ecol Appl. 2025 Jan;35(1):e70001. doi: 10.1002/eap.70001.
Despite decades of progress, much remains unknown about successional trajectories of carbon (C) cycling in north temperate forests. Drivers and mechanisms of these changes, including the role of different types of disturbances, are particularly elusive. To address this gap, we synthesized decades of data from experimental chronosequences and long-term monitoring at a well-studied, regionally representative field site in northern Michigan, USA. Our study provides a comprehensive assessment of changes in above- and belowground ecosystem components over two centuries of succession, links temporal dynamics in C pools and fluxes with underlying drivers, and offers several conceptual insights to the field of forest ecology. Our first advance shows how temporal dynamics in some ecosystem components are consistent across severe disturbances that reset succession and partial disturbances that slightly modify it: both of these disturbance types increase soil N availability, alter fungal community composition, and alter growth and competitive interactions between short-lived pioneer and longer-lived tree taxa. These changes in turn affect soil C stocks, respiratory emissions, and other belowground processes. Second, we show that some other ecosystem components have effects on C cycling that are not consistent over the course of succession. For example, canopy structure does not influence C uptake early in succession but becomes important as stands develop, and the importance of individual structural properties changes over the course of two centuries of stand development. Third, we show that in recent decades, climate change is masking or overriding the influence of community composition on C uptake, while respiratory emissions are sensitive to both climatic and compositional change. In synthesis, we emphasize that time is not a driver of C cycling; it is a dimension within which ecosystem drivers such as canopy structure, tree and microbial community composition change. Changes in those drivers, not in forest age, are what control forest C trajectories, and those changes can happen quickly or slowly, through natural processes or deliberate intervention. Stemming from this view and a whole-ecosystem perspective on forest succession, we offer management applications from this work and assess its broader relevance to understanding long-term change in other north temperate forest ecosystems.
尽管历经数十年的研究进展，但对于北温带森林碳（C）循环的演替轨迹仍有许多未知之处。这些变化的驱动因素和机制，包括不同类型干扰的作用，尤其难以捉摸。为了填补这一空白，我们综合了在美国密歇根州北部一个经过充分研究且具有区域代表性的野外站点通过实验年代序列和长期监测获得的数十年数据。我们的研究全面评估了两个世纪演替过程中地上和地下生态系统组成部分的变化，将碳库和通量的时间动态与潜在驱动因素联系起来，并为森林生态学领域提供了一些概念性见解。我们的第一个进展表明，一些生态系统组成部分的时间动态在重置演替的严重干扰和轻微改变演替的部分干扰中是一致的：这两种干扰类型都会增加土壤氮的有效性，改变真菌群落组成，并改变短命先锋树种和长寿树种之间的生长和竞争相互作用。这些变化进而影响土壤碳储量、呼吸排放以及其他地下过程。其次，我们表明其他一些生态系统组成部分对碳循环的影响在演替过程中并不一致。例如，冠层结构在演替早期不影响碳吸收，但随着林分的发展变得重要，并且在两个世纪的林分发展过程中，个体结构特性的重要性会发生变化。第三，我们表明在最近几十年，气候变化正在掩盖或超越群落组成对碳吸收的影响，而呼吸排放对气候和组成变化都很敏感。综合来看，我们强调时间不是碳循环的驱动因素；它是一个维度，在这个维度内，诸如冠层结构、树木和微生物群落组成等生态系统驱动因素会发生变化。这些驱动因素的变化，而非森林年龄的变化，才是控制森林碳轨迹的因素，并且这些变化可以通过自然过程或人为干预快速或缓慢地发生。基于这一观点以及对森林演替的全生态系统视角，我们从这项工作中提供了管理应用，并评估了其与理解其他北温带森林生态系统长期变化的更广泛相关性。
