The impact of permafrost thaw on ecosystem carbon balance: CiPEHR Project Phenology of Dominant Plant Species III - Flower Biomass

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 warmign 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 achieve using an automated pumping system that lowers the water table in the dry plots. Soil warming began in 2008; OTCs and drying in 2011. This data set includes measured values of CO2 fluxes during the growing season.本干湿与增温实验旨在解答以下科学问题：1. 生态系统干湿化、增温及永久冻土融化是否会引发碳从生态系统向大气的净释放，抑或生态系统对碳的净吸收？2. 占土壤碳库主体的老旧碳的分解作用，是否会影响生态系统的碳流失？3. 干湿化与增温会如何影响植物群落与生态系统属性？本研究依托增温干湿耦合实验平台（DryPEHR）解答上述问题，该平台与永久冻土碳实验加热研究（Carbon in Permafrost Experimental Heating Research, CiPEHR）项目整合部署，选址于阿拉斯加山脉山麓、阿拉斯加州希利镇附近的高地苔原野外站点。本实验的增温处理方案为：生长季利用开顶式气室（Open Top Chambers, OTC）提升空气温度，升温幅度约1℃；积雪期则通过雪栅栏实现土壤增温。干湿化处理通过自动化抽水系统实现，该系统可降低干旱样地的地下水位。土壤增温实验于2008年启动，开顶式气室安装与干湿化处理则于2011年开始实施。本数据集包含生长季内的二氧化碳（CO₂）通量实测数据。