White Spruce 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）样地的调查数据，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年的森林调查，其中1997年至2008年间共生成4组生长增量数据。数据按径级（以10 cm为增量划分）进行统计，包含净初级生产力（Net Primary Productivity, NPP）增量——该增量为各景观单元与演替阶段内所有林木的平均值，且对应样地内林木数量充足（通常不少于5株）以保证测量结果可靠（详见数据文件中的N字段）。