TeRaBio - Manipulating Temperature, Rainfall, and Biodiversity: Aboveground peak biomass

Ecosystems are undergoing and will continue to experience multiple, simultaneous global changes, including the loss of biodiversity, warming, and increased frequency and intensity of droughts. It is largely unknown whether and how these simultaneous shifts will interactively alter ecosystem processes. The Biodiversity and Climate (BAC) experiment (e249) at Cedar Creek has contributed to our understanding of how increasing temperatures can affect ecosystem functioning in communities planted with different numbers and combinations of plant species. Results to date suggest that the warming manipulation in this experiment is not only directly affecting ecosystems through increased temperature, but is also indirectly impacting ecosystems by creating drier soil and microclimate conditions. Such drying effects caused by warming could be exacerbated during droughts, which are expected to become increasingly frequent and intense. To investigate this, we propose to establish a new experiment that fully crosses three treatments: Temperature (ambient or warmed ~1.5??C above ambient), Rainfall (ambient or reduced by ~43%, which corresponds to a 1 in 100 year dry event), and Biodiversity (plots planted with 1, 4, or 16 species). Data collected will include yearly growing season aboveground net primary production, root biomass, soil moisture, relative humidity, light transmittance, and disease prevalence.生态系统目前正处于并将持续经历多重同步的全球变化，包括生物多样性丧失、气候变暖以及干旱发生频率与强度的提升。目前学界尚不清楚这些同步发生的环境变化是否会，以及会如何以交互作用的方式改变生态系统过程。锡达溪（Cedar Creek）生态研究站的生物多样性与气候（Biodiversity and Climate, BAC）实验（编号e249），帮助我们厘清了升温如何影响不同植物数量与组合构建的群落的生态系统功能。截至目前的研究结果表明，该实验中的升温操控不仅通过提升温度直接作用于生态系统，还通过形成更为干燥的土壤与微气候条件，对生态系统产生间接影响。由升温引发的此类干燥效应，在干旱期间可能会进一步加剧——而未来干旱的发生频率与强度预计将持续提升。为探究这一问题，我们提议开展一项全新的全因子交叉实验，设置三类处理因子：温度（对照环境条件或较对照升温约1.5℃）、降雨（对照环境条件或减少约43%，该降幅对应百年一遇的干旱事件）以及生物多样性（样地分别种植1、4或16种植物）。本次实验将收集的观测数据包括：生长季年度地上净初级生产力、地下根系生物量、土壤含水量、相对湿度、光照透射率以及病害发生率。