Eight Mile Lake Research Watershed, Carbon in Permafrost Experimental Heating and Drying Research (DryPEHR): Phenology of Dominant Plant Species III - Flowering Date 2013-2018

This drying and warming experiment addresses the following questions: 1) Does ecosystem drying, warming and permafrost thaw cause a net release or uptake of C from the ecosystem to the atmosphere?, 2) Does the decomposition of old C that comprises the bulk of the soil C pool influence ecosystem C loss? 3) How do drying and warming affect plant communities and ecosystem properties? We are answering these questions using a combined warming and drying experiment (DryPEHR), which is situated with the Carbon in Permafrost Experimental Heating Research (CiPEHR) project and located in an upland tundra field site near Healy, Alaska in the foothills of the Alaska Range. Warming treatment here refers to growing season air temperature warming (~1C) using open top chambers (OTC) combined with soil 'warming' using snow fences during the snow covered months. Drying is achieved using an automated pumping system that lowers the water table in the dry plots. Soil warming began in 2008; OTCs and drying in 2011. In this dataset we specifically ask, how does warming and drying of soil and air impact the phenology of dominant plant species? Phenological data was collected to determine the timing of first bud break, onset and completion of senescence, and reproductive effort (flower and berry production).本干湿增温实验旨在解答以下三项科学问题：1）生态系统干旱化、增温与永久冻土融化，是否会引发碳从生态系统向大气的净释放，或是净碳吸收？2）占土壤碳库主体的老旧碳的分解过程，是否会对生态系统的碳损失产生影响？3）干旱化与增温如何作用于植物群落与生态系统各项属性？本研究依托联合增温-干旱实验平台DryPEHR开展相关研究，该平台与永久冻土碳实验加热研究（Carbon in Permafrost Experimental Heating Research, "CiPEHR"）项目共址，设置于阿拉斯加山脉山麓、阿拉斯加州希利镇附近的高地苔原样地。本实验的增温处理包含两部分：积雪期通过雪篱实现土壤增温，生长季则利用开顶式气室（open top chambers, "OTC"）将空气温度提升约1℃。干旱处理通过自动化抽水系统降低样地地下水位得以实现。土壤增温实验于2008年正式启动，而开顶式气室布设与干旱处理则于2011年开始实施。本数据集聚焦的核心科学问题为：土壤与空气的增温、干旱化如何影响优势植物物种的物候特征？研究人员采集了物候相关数据，用于确定首个芽萌动时间、衰老启动与完成节点，以及植物繁殖投入水平（开花与浆果结实量）。