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. 随着气候变化引发干旱胁迫日益加剧，解析植物的水分利用策略恰逢其时。尽管根系在水分吸收过程中发挥着核心作用，但水分利用与根系性状之间的关联却极少被纳入研究范畴。 2. 本研究将基于功能性状的研究方法与水量平衡模型（water balance model）相结合，在同质园（common garden）单栽试验条件下，针对12种地中海牧场（Mediterranean rangeland）植物，检验了其根系功能性状与时空水分利用之间的关联。研究连续10个月监测土壤含水量，并以日时间步长对各物种的水分吸收动态进行建模。同时在两层土壤深度（浅层与深层土壤）下测定了根系功能性状。 3. 浅层土壤中具备快速资源获取策略的物种（即拥有细根的物种），可在短期内实现水分吸收最大化，并在水分可利用性较低的时段消耗大量水分。与之相对，采用保守型根系策略的物种（即拥有粗根的物种），在生长旺季的水分吸收量较低，但其水分吸收过程可维持更长时长，并在水分可利用性较低的时段消耗更少水分。深层根系性状与物种从深层土壤获取水分的能力紧密相关：直径较大、比根长（specific root length）较低的深根，可提升物种从深层土壤获取水分的能力。深层土壤层的生物量投入，与水分可利用性较低时段的耗水量呈正相关关系。 4. 本研究结果揭示，根系功能性状会影响地中海牧场植物的一系列时空水分利用模式。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整体水分利用情况。