Variation in desert shrub foliar pH in relation to drought and salinity in Xinjiang, China

Abstract

AbstractAimFoliar pH, an emerging plant functional trait, plays a key role in plant eco‐physiological processes. However, it remains unclear how foliar pH varies among plants with different preferences concerning soil salinity, and how it responds to drought stress in desert ecosystems.LocationXinjiang, northwestern China (40.24° N to 46.24° N, 80.66° E to 91.33° E).MethodsWe addressed variation in foliar pH in four desert shrub groups (i.e., euhalophytes, secretohalophytes, pseudohalophytes and glycophytes) with differing adaptive strategies to soil salinity in 29 sites in Xinjiang, China, and explored the effects of drought and saline stress on foliar pH variability.ResultsWe found that average foliar pH of desert shrubs was 5.54 ± 0.02, higher than that of shrubs from humid areas. At the functional group level, euhalophytes (5.65 ± 0.03) and glycophytes (5.61 ± 0.04) had significantly higher foliar pH than secretohalophytes (5.47 ± 0.03) and pseudohalophytes (5.39 ± 0.05). Coverage‐weighted mean foliar pH of glycophytes‐dominated communities was significantly higher (5.80 ± 0.18) than those of the halophytes‐dominated communities (5.34 ± 0.07 ~ 5.49 ± 0.07). Only in pseudohalophytes there was a significant relationship between foliar pH and both drought stress (i.e., low soil water stress coefficient, aridity index, and mean annual precipitation) and saline stress (shown by high soil electrical conductivity and soil pH). In contrast, secretohalophytes displayed opposite or non‐significant relationships between foliar pH and drought and saline stress. Compared with salinity indicators, drought exerted a much larger impact on foliar pH, particularly in pseudohalophytes and secretohalophytes.ConclusionsOur work documented a comprehensive analysis of foliar pH across halophyte and glycophyte shrub species, and found contrasting responses of foliar pH to drought and salinity in desert ecosystems, which can provide an alternative perspective for understanding the survival strategies of desert plants, and may also offer new insights into the population dynamics of desert shrub communities under global climate change.