Data from: Root traits are related to plant water-use among rangeland Mediterranean species

1. Understanding the water-use of plants is timely under increasing drought stress due to climate change. Despite the crucial role of roots in water uptake, relationships between water-use and root traits are seldom considered. 2. Combining a functional traits-based approach with a water balance model, we tested whether root functional traits are related to spatial and temporal water-use among 12 Mediterranean rangeland species grown in common garden monocultures. Soil water content was monitored for 10 months, and the dynamics of water uptake of each species was modelled at a daily time step. Root functional traits were measured at two soil depths (shallow and deep soil). 3. Species with fast resource acquisition strategies in shallow soil, i.e. thin roots, maximised water uptake in a short period and consumed large amounts of water during periods of low water availability. Conversely, species with a more conservative root strategy, i.e. coarse roots, took up less water during the peak-growing season, maintained water uptake over a longer period of time and consumed less water during periods of low water availability. Deep root traits are strongly related to species’ ability to take up water from deep soil. Deep roots with large diameters and low specific root length improve species’ ability to reach water from deep soil. Biomass investment in the deep soil layer was positively related to the amount of water consumed during periods of low water availability. 4. Our results highlight that root functional traits influence a range of spatial and temporal water-use among Mediterranean rangeland species. They account for the amount of water taken up during dry periods but not during the entire growing season.

1. 在气候变化导致干旱胁迫加剧的背景下，解析植物的水分利用策略具有重要的现实意义。尽管根系在水分吸收过程中发挥着关键作用，但水分利用与根系功能性状（functional traits）之间的关联却鲜有研究关注。2. 本研究结合基于功能性状的研究方法与水量平衡模型（water balance model），针对12种在同质园（common garden）中单作栽培的地中海牧场（Mediterranean rangeland）物种，检验根系功能性状是否与其空间及时间维度的水分利用模式存在关联。研究对土壤含水量开展了为期10个月的连续监测，并以日时间步长对各物种的水分吸收动态进行建模。同时，我们在两个土壤深度（浅层与深层土壤）下测定了根系功能性状。3. 在浅层土壤中采用快速资源获取策略的物种（即具细根的物种），可在短时间内实现水分吸收最大化，并在水分可利用性较低的时期消耗大量水分。与之相反，采用更为保守根系策略的物种（即具粗根的物种），在生长旺季的水分吸收量更低，却可在更长时段内维持水分吸收，并在水分可利用性较低的时期消耗更少水分。深层根系性状与物种从深层土壤获取水分的能力密切相关：直径较大、比根长（specific root length）较低的深层根系，可提升物种获取深层土壤水分的能力。对深层土壤层的生物量投入与低水分可利用性时期的耗水量呈正相关关系。4. 本研究结果表明，根系功能性状会对地中海牧场物种的一系列空间及时间维度的水分利用模式产生影响。这些性状能够解释干旱时期的水分吸收量，但无法解释整个生长季的总耗水量。