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Abstract QuestionsPredicting the influence of climate change on riparian plant communities improves management strategies. The sensitivity of riparian vegetation to climate and other abiotic factors depends on interactions between properties of the ecosystem, like flood regime, and plant characteristics. To explore these interactions, we addressed three questions: (a) does the composition and diversity of riparian vegetation vary with the flood regime; (b) do abiotic correlates of vegetation, including climate and groundwater, differ between sites that flood compared to locations that did not experience floods; and (c) which plant functional groups account for differential plant community sensitivity to abiotic factors between flood regimes? LocationMiddle Rio Grande Valley, New Mexico. MethodsWe used long‐term observations of plant community composition, groundwater depth, precipitation and interpolated temperature from 24 sites spanning 210 km of the Rio Grande riparian cottonwood–willow forest to explore the relative importance of climate and hydrologic correlates of riparian vegetation diversity and composition. ResultsRiparian plant diversity was higher at sites flooding compared to non‐flooding sites. Plant diversity positively tracked shallower groundwater depth at flooding sites, but was best predicted by intra‐annual groundwater variability at non‐flooding sites. Plant community composition correlated with groundwater depth and air temperature at all sites, but at non‐flooding sites, also with intra‐annual groundwater variability and precipitation. Relationships between native plant cover and potential environmental drivers diverged strongly between the two flood regimes; non‐native plant cover had only weak relationships with most environmental predictors. ConclusionsThe current flood regime of a site determined the climate and hydrologic factors that best predicted riparian plant community composition and diversity. Relationships between plant diversity or total cover and groundwater, temperature, precipitation, or groundwater variability can change in strength or direction depending on a site's flood history, highlighting the importance of flood regime to predicting the sensitivity of riparian woodlands to future environmental change. 

Abstract QuestionsIt is frequently reported that overstocking of camels, cattle and goats is degrading theAnogeissuscloud forest, which is endemic to a 200‐km stretch of coastal mountains in southern Arabia. However, livestock impacts on the vegetation have not been assessed. Furthermore, we have a limited understanding of the impacts of large‐bodied browsing livestock, such as camels, in woodland and forest rangelands. Therefore, in this study, we examine the effects of livestock browsing on the species composition, density, and phytomorphology of woody vegetation in theAnogeissuscloud forests in the Dhofar Mountains of Oman. LocationData were collected at 30 sites in the Jabal Qamar mountain range in western Dhofar, Oman. MethodsThe point‐centred quarter method was used to sample the composition, density and structure of woody vegetation. Constrained correspondence analysis was used to quantify the effects of livestock browsing on woody plant species composition, whilst effects on plant density were analysed using mixed‐effects models. Standardised major axis regression was used to examine differences in height–diameter allometry (stunting) under different stocking rates. ResultsFog density, topographic position and long‐term stocking rates were found to be important factors affecting woody species composition. We found lower species diversity and plant density, and higher frequencies of unpalatable species, under higher stocking rates. Juveniles showed a stronger response to stocking rates than adults, and several common species exhibited stunted morphology under high stocking rates. ConclusionsBrowsing by large‐bodied livestock, such as camels and cattle, can substantially alter the species composition, structure, and phytomorphology of woody vegetation in semi‐arid woodlands and forests. Juveniles are particularly susceptible to browsing which alters woody vegetation demography and inhibits regeneration potential. Our results support previous suggestions of overstocking in Dhofar and highlight the importance of swift measures to reduce livestock browsing pressure in theAnogeissuscloud forests.