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Summary: Understanding how plant communities respond to temporal patterns of precipitation in water‐limited ecosystems is necessary to predict interannual variation and trends in ecosystem properties, including forage production, biogeochemical cycling, and biodiversity.In North American shortgrass prairie, we measured plant abundance, functional traits related to growth rate and drought tolerance, and aboveground net primary productivity to identify: species‐level responsiveness to precipitation (precipitation sensitivity Sspp) across functional groups; Sspp relationships to continuous plant traits; and whether continuous trait–Sspp relationships scaled to the community level.Across 32 plant species, we found strong bivariate relationships of both leaf dry matter content (LDMC) and leaf osmotic potential Ψosm with Sspp. Yet, LDMC and specific leaf area were retained in the lowest Akaike information criterion multiple regression model, explaining 59% of Sspp. Most relationships between continuous traits and Sspp scaled to the community level but were often contingent on the presence/absence of particular species and/or land management at a site.Thus, plant communities in shortgrass prairie may shift towards slower growing, more stress‐resistant species in drought years and/or chronically drier climate. These findings highlight the importance of both leaf economic and drought tolerance traits in determining species and community responses to altered precipitation. [ABSTRACT FROM AUTHOR]

Community-scale surveys of plant drought tolerance are essential for understanding semi-arid ecosystems and community responses to climate change. Thus, there is a need for an accurate and rapid methodology for assessing drought tolerance strategies across plant functional types. The osmometer method for predicting leaf osmotic potential at full turgor (πo), a key metric of leaf-level drought tolerance, has resulted in a 50-fold increase in the measurement speed of this trait; however, the applicability of this method has only been tested in woody species and crops. Here, we assess the osmometer method for use in herbaceous grassland species and test whether πo is an appropriate plant trait for understanding drought strategies of herbaceous species as well as species distributions along climate gradients. Our model for predicting leaf turgor loss point (πTLP) from πo (πTLP = 0.80πo-0.845) is nearly identical to the model previously presented for woody species. Additionally, πo was highly correlated with πTLP for graminoid species (πtlp = 0.944πo-0.611; r2 = 0.96), a plant functional group previously flagged for having the potential to cause erroneous measurements when using an osmometer. We report that πo, measured with an osmometer, is well correlated with other traits linked to drought tolerance (namely, leaf dry matter content and leaf vulnerability to hydraulic failure) as well as climate extremes linked to water availability. The validation of the osmometer method in an herb-dominated ecosystem paves the way for rapid community-scale surveys of drought tolerance across plant functional groups, which could improve trait-based predictions of ecosystem responses to climate change. [ABSTRACT FROM AUTHOR]

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