Nitrogen Fertilization Experiment (NFert): Seasonal Biomass and Seasonal and Annual NPP Data at the Sevilleta National Wildlife Refuge, New Mexico (2004- )

Begun in spring 2004, this long-term study at the Sevilleta LTER examines how fertilization affects above-ground biomass production (ANPP) in a mixed desert-grassland. Net primary production is a fundamental ecological variable that quantifies 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 to a range of ecological processes.  While measures of both below- and above-ground biomass are important in estimating total NPP, this study focuses on above-ground net primary production (ANPP). Above-ground net primary production is the change in plant biomass, including loss to death and decomposition, over a given period of time. Volumetric measurements are made using vegetation data from permanent plots (SEV155, "Nitrogen Fertilization Experiment (NFert): Net Primary Production Quadrat Data") and regressions correlating species biomass and volume constructed using seasonal harvest weights from SEV157, "Net Primary Productivity (NPP) Weight Data." This site was burned by a prescribed fire in 2003.

本研究于2004年春季启动，为塞维利塔长期生态研究站（Sevilleta LTER）开展的长期观测项目，旨在探究施肥对混合荒漠草原地上净初级生产力（Above-ground Net Primary Production, ANPP）的影响机制。净初级生产力（Net Primary Production, NPP）是表征碳消耗与固定速率的核心生态变量，对其的准确估算可为理解群落尺度的能量流动，以及生态过程驱动下的时空响应特征提供关键支撑。尽管地下与地上生物量的测定对总净初级生产力的估算不可或缺，但本研究聚焦于地上净初级生产力（ANPP）。地上净初级生产力指特定时段内植物生物量的变化量，涵盖死亡与分解过程导致的生物量损失。体积测量工作依托两类数据开展：一是永久样地（SEV155, "氮肥施肥实验（NFert）：净初级生产力样方数据"）的植被观测数据，二是基于SEV157数据集"净初级生产力（NPP）重量数据"的季节性收获权重所构建的物种生物量与体积相关回归模型。该研究站点曾于2003年实施计划火烧。