Aspen NPP: average NPP per tree by diameter sizeclass for 4 time periods between 1993 and 2008

This data set is derived from BNZ LTER inventory plots, where DBH of all trees is measured every 3 to 4 years, and increment changes in AG biomass are derived from allometric equations. Data included in this file were obtained from 1993, 1997, 2000, 2004 and 2008 inventories, generating 4 growth increments between 1997 and 2008. Data are reported by diameter sizeclass (10 cm increments), and include NPP increments (averaged across all trees within each landscape and successional stage) for which adequate numbers of trees (typically >5) were present to obtain useful measurements (see N in data file).本数据集源自BNZ长期生态研究（Long-Term Ecological Research, LTER）样地，该样地内所有林木的胸径（Diameter at Breast Height, DBH）每3至4年测定一次，地上生物量（Aboveground biomass, AG biomass）的增量变化通过异速生长方程推导得出。本文件收录的数据来自1993、1997、2000、2004及2008年的林木清查，共生成1997至2008年间的4个生长增量时段。数据按级差为10 cm的径级进行统计，同时涵盖净初级生产力（Net Primary Productivity, NPP）增量——该增量为每个景观单元与演替阶段内符合统计要求的林木平均值，仅纳入样本量充足（通常≥5株）以获得有效测量结果的分组（详见数据文件中的N字段）。