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

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.

本项于2004年春季启动的长期研究依托塞维列塔长期生态研究站（Sevilleta LTER），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。净初级生产力（Net Primary Production, NPP）是衡量碳消耗与固碳速率的核心生态变量，其估算结果对于解析群落层级的能量流动，以及诸多生态过程的时空响应均具有重要价值。尽管地下与地上生物量的测定对总NPP估算至关重要，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，其中包含死亡与分解导致的生物量损失。本研究的体积测量通过两类数据完成：一是取自永久样地（SEV155，《氮肥添加试验（NFert）：净初级生产力样方数据》）的植被数据，二是基于SEV157数据集《净初级生产力（NPP）重量数据》中季节性收获重量构建的物种生物量与体积相关性回归模型。该研究样地于2003年实施了控制性火烧。