Ecophysiological Response of Native and Invasive Grasses with Warming
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Climate change, anthropogenic disturbances and lack of proper management practices have rendered many arid regions susceptible to invasions by exotic grasses with consequent ecohydrological, biogeochemical and socio economic implications. Thus, understanding the ecophysiological processes driving these large-scale vegetation shifts in drylands, in the context of rising temperatures and recurrent droughts is fundamental to global change research. Using the Biosphere 2 facility to maintain distinct temperature treatments of ambient and predicted warmer conditions (+ 4o C) inside, we compared the physiological responses (e.g. photosynthesis, stomatal conductance, biomass) of a native grass - Heteropogan contortus (tanglehead) and an invasive grass - Pennisetum ciliare (buffelgrass) growing in single and mixed communities. The results indicate that buffelgrass can assimilate more CO2 per unit leaf area under current conditions, though warming seems to inhibit the performance when looking at biomass, photosynthesis and stomatal conductance. Under similar moisture regimes buffelgrass performed better than tanglehead in mixed communities regardless of the temperature. Both grasses had decreased stomatal conductance with warmer conditions when they were grown singly; however, the buffelgrass did not have the same decrease of conductance when planted in a mixed communities.