Fallon, B., and J. Cavender‐Bares. 2018. Leaf‐level trade‐offs between drought avoidance and desiccation recovery drive elevation stratification in arid oaks. Ecosphere 9(3):e02149. https://doi.org/10.1002/ecs2.2149 contact: eafallon@umn.edu/gmail.com MS abstract: Understanding the extent to which climate limitations drive elevation stratification among species is integral to predicting the impacts of climate change. Zonation patterns of species within mountains have been well-documented, and shifts in these patterns have been correlated with recent warming. However, the physiological mechanisms that explain these zonation patterns are not well understood. We used a system of broadly sympatric oak species within semi-arid mountains to 1) investigate the extent to which species elevation ranges correlate with climate, 2) test for associations of cold and drought resistances with upper and lower elevation limits, and for trade-offs between resistance mechanisms with elevation, and 3) examine the extent to which species-wide climatic ranges predict traits that drive local community assembly along an elevation gradient. We found that aridity gradients but not winter minimum temperatures predict oak stratification. Species differed in drought resistance, demonstrating a trade-off between drought avoidance and drought recovery. At lower elevations, species avoided drought stress during the dry season through leaf abscission; at upper elevations they maintained transpiration but recovered from daily desiccation via higher leaf storage capacity, rather than tolerating desiccation via lower turgor loss points. Freezing resistance, measured as stem electrolyte leakage, was not correlated with elevation differences. Taken together, these results indicate that elevation stratification is linked to drought resistance rather than freezing resistance. We also found evidence of niche partitioning among closely-related oaks linked to contrasting leaf phenology. The functional, phenological, and physiological traits important for elevation stratification were correlated with species range-wide mean annual precipitation and precipitation seasonality, but not aridity. Our findings indicate that drought resistance along a leaf avoidance-recovery trade-off is integral to species stratification within this semi-arid montane system. Additionally, the mechanism of stratification acts upon traits and strategies conserved at the species level. Species within this system are likely vulnerable to range retraction under increased drought as a consequence of this phenological avoidance-physiological tolerance trade-off. keywords: range limits, community assembly, drought resistance, freezing resistance, niche partitioning, ecophysiology, climate limitations Data abstract: This dataset and RStudio project includes all processed data, most raw data, and R scripts needed for analysis and figure construction included in the manuscript Fallon and J. Cavender-Bares 2018 (Fallon B. and J. Cavender-Bares. 2018. Leaf-level trade-offs between drought avoidance and desiccation recovery drive elevation stratification in arid oaks. Ecosphere. in press). We investigated whether oak species in the Chiricahua Mountains were 1) elevationally stratified, 2) whether that stratification was correlated with temperature minima, maxima, and water availability, 3) if physiological tolerances to freezing or drought stress correlated with elevation ranges, and 4) if traits important to local (elevation) distributions were correlated with climatic values of the wider species ranges. Data were collected at field sites from wild, adult trees in the Chiricahua Mountains, Arizona, USA from 2014-2015.This research was done with funding to B. Fallon from the Southwestern Research Station (SWRS, American Museum of Natural History), the University of Minnesota Charles J. Brand, Carolyn Crosby, and Dayton Bell Fellowships, and the Department of Plant and Microbial Biology. Additional funding was provided by NSF Award 1146380 (J. Cavender-Bares PI). We performed all data collection under permit with the Coronado National Forest, Douglas Ranger District, managed by the United States Forest Service (USDA). All scripts and data will run in the RStudio Project "Leaf-level tradeoffs oaks AZ.Rproj" Only four scripts are necessary for analyses and figure production: 1) 1_clim_summaries_figs: local site temperature (collected from iButtons) 2) 2_spp_optima_v3: elevation distributions of oak species 3) 3_electro_Leakage_3_models_figures: analyses and figures of experimental stem freezing damage 4) 4_physio_data_v4: leaf level physiological data (water potentials, turgor loss point and capacitance, leaf phenology) and stem freezing data analyses and figures, inlcuding trait correlations and traits to wider range correlations. Scripts within /data_prep_scripts either run within the above scripts or were used for data clean-up All folders preceded by "input_", the gen_data, and the hipp_etal folder include README descriptions within the folder All folders preceded by "output_" include files generated within the scripts Citations for all R packages are in the above manuscript, all analyses done in R v3.4.1 The Hipp_etal folder contains the oak phylogeny from Hipp, A. L., P. S. Manos, A. Gonzolez-Rodriguez, M. Hahn, M. Kaproth, J. D. McVay, S. V. Avalos, and J. Cavender-Bares. 2018. Sympatric parallel diversification of major oak clades in the Americas and the origins of Mexican species diversity. New Phytologist 217:439-452. doi: 10.1111/nph.14773. Data can be found on DRYAD at: doi:10.5061/dryad.j4sf2. This phylogeny is used as the tree for phylogenetically independent contrasts of traits and species range wide climate variables. The gen_data folder contains site and individual plant descriptive data, as well as physiological (with the exception of the electrolyte leakage data) and phenological data. Some data within the data_gen folder are from Hijmans et al 2005 WorldClim v1 (Hijmans, R.J., S.E. Cameron, J.L. Parra, P.G. Jones and A. Jarvis, 2005. Very high resolution interpolated climate surfaces for global land areas. International Journal of Climatology 25: 1965-1978.).