Physical, chemical, and metabolic leaf characteristics within sugar maple in the MELNHE study at Bartlett Experimental Forest, central NH USA, 2017

The MELNHE study looks at patterns of resource limitation through
nutrient manipulations in three study sites in New Hampshire: Bartlett
Experimental Forest, Hubbard Brook Experimental Forest, and Jeffers
Brook, located in the White Mountain National Forest. The
investigation is 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.
Applications of N and P began in June 2011 and continue at the rate of
30 kg N/ha/yr (as NH4NO3) and 10 kg P/ha/yr (as NaH2PO4).

This data set includes physical, chemical, and metabolic leaf
characteristics collected in a vertical transect within individual
tree crowns. Because trees varied in crown depth, not all trees have
the same number of samples collected. Depth from the top of the crown
was measured and climbing ropes and a pole pruner were used to collect
a population of leaves.

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.

MELNHE研究通过养分操控实验，在新罕布什尔州的三个研究站点——巴特利特实验林（Bartlett Experimental Forest）、哈伯德布鲁克实验林（Hubbard Brook Experimental Forest）以及位于怀特山国家森林的杰弗斯布鲁克（Jeffers Brook）——探究资源限制模式。本调查持续监测多项指标：树干直径、叶面积、树液流量、叶片化学组成、枯落叶产量与化学特性、叶片养分重吸收效率、根系生物量与生产力、菌根共生关系、土壤呼吸、异养呼吸、氮（N）与磷（P）有效性、氮矿化作用、土壤磷酸酶活性、土壤碳与氮含量、根系养分吸收能力以及矿物风化作用。氮（以硝酸铵NH4NO3形式）与磷（以磷酸二氢钠NaH2PO4形式）的施加始于2011年6月，施加速率分别为30 kg N/ha/yr与10 kg P/ha/yr，并持续至今。

本数据集包含单株树木冠层垂直样带内采集的叶片物理、化学及代谢特征。由于不同树木的冠层深度存在差异，并非所有树木的采样数量均一致。研究人员以冠层顶部为基准测量采样深度，并借助攀岩绳索与高枝剪采集叶片样本。

这些数据作为哈伯德布鲁克生态系统研究（Hubbard Brook Ecosystem Study, HBES）的一部分被收集。HBES是由哈伯德布鲁克实验林开展的合作研究项目，该实验林由美国农业部林业局北部研究站运营维护。