Long-term Plant Biomass Monitoring Data from the Georgia Coastal Ecosystems LTER Project on Sapelo Island, Georgia

The Georgia Coastal Ecosystems LTER program (GCE) monitors plant biomass annually with the goal of testing the hypothesis that end-of-year biomass varies as a function of 1) freshwater discharge from the Altamaha River (especially in low-marsh plots), 2) local rainfall (especially in high-marsh plots), and 3) average sea level. In 2000 we created permanent plots at all 10 GCE marsh monitoring sites. Plots were established at creek-bank and mid-marsh sites (8 plots per zone per site). Most sites are dominated by Spartina alterniflora (smooth cordgrass), but zones at some sites are dominated by Juncus roemerianus, Spartina cynosuroides, or Zizaniopsis miliacea. An additional marsh zone (high marsh Juncus) was established at site 10 in 2005 and site 9 in 2012 to increase replication of sites with Juncus. Plants have been non-destructively monitored in October of every year from 2000 to the present, measuring the stem count, height and flowering status of every plant in each plot. Stem clipping samples were also collected adjacent to plots in 2002, 2007, and 2020, then measured, dried, weighed and statistically analyzed in order to generate allometric regression relationships between height and mass for estimation of plant biomass in corresponding plots. This data set includes cumulative long-term observations of plant stem count, height and biomass per marsh zone, plot and species at 10 GCE LTER sampling sites from 2000 to 2022, and will be updated annually to include the prior year observations.

佐治亚海岸生态系统长期生态研究（Long-Term Ecological Research，LTER）项目（简称GCE）每年开展植物生物量监测工作，旨在验证如下假说：年末植物生物量随三个因素变化：1）奥塔莫哈河淡水径流量（尤其在低沼泽样地中）、2）局地降雨量（尤其在高沼泽样地中）以及3）平均海平面高度。2000年，研究团队在全部10个GCE沼泽监测点位设立永久样地：每个点位的溪岸带与沼泽中部带各设置8个样地。多数监测点位的优势植被为互花米草（*Spartina alterniflora*），但部分点位的分区优势种为具茎灯心草（*Juncus roemerianus*）、芦苇状米草（*Spartina cynosuroides*）或野稻（*Zizaniopsis miliacea*）。2005年，研究团队在点位10增设高沼泽具茎灯心草分区；2012年，又在点位9增设该分区，以增加具茎灯心草优势点位的样本重复量。2000年至今，研究团队于每年10月对样地内所有植株开展非破坏性监测，记录每株植物的茎秆数量、株高及开花状态。2002、2007及2020年，团队还在样地附近采集茎秆剪取样本，经测量、烘干、称重后开展统计分析，以建立株高与生物量之间的异速回归关系，用于估算对应样地内的植物生物量。本数据集涵盖2000年至2022年10个GCE LTER监测点位各沼泽分区、样地及物种的植物茎秆数量、株高与生物量的长期累积观测数据，且将每年更新以纳入上一年度的观测结果。