Multiple Element Limitation in Northeast Hardwood Ecosystems (MELNHE): Project description, plot characteristics and design

Although temperate forests are generally thought of as N-limited, resource optimization theory predicts that ecosystem productivity should be co-limited by multiple nutrients. These ideas are represented in the Multi-Element Limitation (MEL) model (Rastetter et al. 2012). To test the patterns of resource limitation predicted by MEL, we are conducting nutrient manipulations in three study sites in New Hampshire: Bartlett Experimental Forest (BEF), Hubbard Brook Experimental Forest (HBEF), and Jeffers Brook in the White Mountain National Forest. We are monitoring stem diameter, leaf area, sap flow, foliar chemistry, leaf litter production and chemistry, foliar nutrient resorption, root biomass and production, mycorrhizal associations, soil respiration, heterotrophic respiration, N and P availability, N mineralization, soil phosphatase activity, soil carbon and nitrogen, nutrient uptake capacity of roots, and mineral weathering. These data can be found in the EDI repository, using the search term "MELNHE" (http://portal.edirepository.org), and through the data catalog on https://hubbardbrook.org, using the same search term. This data package is referenced by the MELNHE datasets, and includes a datatable of site descriptions and a pdf file with the project description, and diagrams of plot configuration. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.尽管温带森林通常被认为受氮（N）限制，但资源优化理论预测，生态系统生产力应受到多种养分的共同限制。这些理论观点体现在多元素限制（Multi-Element Limitation, MEL）模型（Rastetter等，2012）中。为验证MEL模型所预测的资源限制模式，我们在新罕布什尔州的3个研究样地开展了养分操控实验：巴特利特实验林（Bartlett Experimental Forest, BEF）、哈伯德布鲁克实验林（Hubbard Brook Experimental Forest, HBEF）以及怀特山国家森林内的杰弗斯溪（Jeffers Brook）。本研究监测的指标包括：茎干直径、叶面积、液流速率、叶片化学组成、凋落物产量与化学组成、叶片养分回收效率、根系生物量与生产量、菌根共生关系、土壤呼吸、异养呼吸、氮（N）与磷（P）有效性、氮矿化、土壤磷酸酶活性、土壤碳氮含量、根系养分吸收能力以及矿物风化作用。此类数据可通过环境数据倡议（Environmental Data Initiative, EDI）数据库（搜索关键词："MELNHE"，访问网址：http://portal.edirepository.org）获取，也可通过哈伯德布鲁克官网（https://hubbardbrook.org）的数据目录，使用相同关键词检索获得。本数据包由MELNHE数据集引用，其中包含样地描述数据表、项目说明PDF文档以及样地配置示意图。本数据集作为哈伯德布鲁克生态系统研究（Hubbard Brook Ecosystem Study, HBES）的一部分采集而成。HBES是在哈伯德布鲁克实验林开展的协同研究项目，该实验林由美国农业部林务局（USDA Forest Service）北方研究站运营维护。