Long-term changes in forest biomass, tree species composition and nitrogen fixation following land use disturbance

These data are from long-term vegetation plots at the Coweeta Hydrologic Laboratory in western North Carolina. Data collection began in 1934-1935 and was repeated roughly a few times each decade between 1970 and 2013. Three different types of disturbances were applied in this study: selective cutting, clear cutting, and agricultural abandonment. The selective cutting experiment included 274 plots located in reference watersheds that received no subsequent disturbance after a selective cutting event in the early 1900s. There were 24 clear-cut disturbance plots which were located in watershed 7, which was clear-cut in 1976-1977. The 34 agriculture abandonment plots were located in watershed 6, which was logged and tilled in 1958 and planted with grass and maintained with fertilizer and herbicide, until abandoned in 1968. This data publication includes the following plot-level data: cumulative nitrogen fixation estimated from Robinia pseudoacacia (ROBPSE) tree density data and a model parameterized with local nitrogen fixation data as well as the maximum total above ground biomass (agb) of ROBPSE at any survey date. In addition, the following data are provided for each survey date (year) and plot: total agb and the mycorrhizal association for 27 common tree species, fraction of agb comprised by arbuscular mycorrhizal (AM) trees (excluding ROBPSE), and total agb (excluding ROBPSE, CASDEN and TSUCAN).
Data were collected to understand changes in forest composition over time and following disturbance. In our study, we examined how historical land use and symbiotic nitrogen fixation relate to patterns in forest composition.
For more information about this study and these data, see Wurzburger et al. [In press].

本数据集源自北卡罗来纳州西部考伊塔水文实验室（Coweeta Hydrologic Laboratory）的长期植被样地。数据采集始于1934—1935年，1970年至2013年间约每十年开展一次重复调查。本研究设置了三类干扰处理：择伐、皆伐与农业弃耕。择伐实验共包含274个样地，位于参照流域内，该流域在20世纪早期的择伐事件后未再遭受任何后续干扰。皆伐干扰样地共24个，位于7号流域，该流域于1976—1977年实施皆伐。农业弃耕样地共34个，位于6号流域；该流域于1958年被采伐并翻耕，后续种植草本并通过施肥、喷施除草剂维持管理，直至1968年弃耕。本数据集包含以下样地水平数据：基于刺槐（Robinia pseudoacacia，缩写ROBPSE）的树木密度数据，以及采用本地固氮数据参数化的模型估算得到的累积固氮量，同时包含任意调查日期下ROBPSE的最大总地上生物量（agb）。此外，本数据集还提供了各调查年份及样地的以下数据：27个常见树种的总agb及其菌根共生类型、丛枝菌根（arbuscular mycorrhizal，简称AM）树木占总agb的比例（不含ROBPSE），以及总agb（不含ROBPSE、CASDEN与TSUCAN）。本数据采集旨在探究森林组成随时间及干扰后的变化规律。本研究聚焦于历史土地利用方式与共生固氮如何影响森林组成格局。如需了解本研究及数据集的更多详情，请参阅Wurzburger等[即将刊出]。