Pinon Juniper Net Primary Production Quadrat Data from the Sevilleta National Wildlife Refuge, New Mexico: 1999-2001

This three-year study at the Sevilleta LTER was designed to monitor net primary production (NPP) across two distinct ecosystems: pinon/juniper woodland (P) and juniper savannah woodland (J). Net primary production (NPP) is a fundamental ecological variable that measures rates of carbon consumption and fixation. Estimates of NPP are important in understanding energy flow at a community level as well as spatial and temporal responses of the community to a wide range of ecological processes. While measures of both below- and above-ground biomass are important in estimating NPP, this study focused on estimating above-ground biomass production (ANPP).To measure ANPP (i.e., the change in plant biomass, represented by stems, flowers, fruit and foliage, over time), the vegetation variables in this dataset, including species composition and the cover and height of individuals, were sampled twice yearly (spring and fall) at permanent 1m x 1m plots. The data from these plots was used to build regressions correlating biomass and volume via weights of select harvested species obtained in SEV157, "Net Primary Productivity (NPP) Weight Data." In addition, volumetric measurements were obtained from permanent plots to build regressions correlating biomass and volume.Spring measurements were taken in April or May when shrubs and spring annuals reached peak biomass. Fall measurements were taken in either September or October when summer annuals reached peak biomass but prior to killing frosts. Winter measurements were taken in February before the onset of spring growth.本研究在塞维利亚塔长期生态研究站（Sevilleta LTER）开展，为期三年，旨在监测两种不同生态系统的净初级生产力（net primary production, NPP）：矮松-桧木林（P）与桧木稀树草原林（J）。净初级生产力是衡量碳消耗与固定速率的核心生态变量，对其进行估算有助于理解群落层面的能量流动，以及群落对各类生态过程的时空响应。尽管地下与地上生物量的测定对NPP估算均至关重要，但本研究聚焦于地上生物量生产量（above-ground biomass production, ANPP）的估算。为测定ANPP，即植物生物量随时间的变化（以茎秆、花、果实及叶片为表征），本数据集通过在永久性1m×1m样地每年两次（春季与秋季）采样，获取物种组成、个体盖度与高度等植被变量。基于这些样地的数据，结合SEV157数据集《净初级生产力（NPP）权重数据》中获取的选定收获物种的生物量权重，构建关联生物量与体积的回归模型。此外，本研究还通过永久性样地获取体积测量数据，用于构建关联生物量与体积的回归模型。春季采样于4月或5月开展，此时灌木与春季一年生植物的生物量达到峰值。秋季采样于9月或10月开展，此时夏季一年生植物生物量达到峰值，且未发生霜冻致死现象。冬季采样于2月开展，即在春季生长启动之前。