Similar post-drought functional trait response of native and exotic plant species in southwestern Arizona

Abstract

Extreme climate events such as severe drought and heatwaves are expected to increase in intensity, frequency, and duration across the southwestern USA. Understanding plant responses to such events can give us insight into the impact they have on plant communities and the communities' potential resilience. Plant functional traits (mean and variation) can provide insight into species’ drought response. We explored how mean and variance of trait values within species shifts in a drought year and the following wet year in southwestern Arizona. We also examined the response of different plant identities: life form (grass and forb) and native status (native and exotic). We measured 10 different functional traits on 12 species across both years and compared trait shifts across the two years. We found that most species displayed large trait shifts towards more acquisitive functional strategies in the wet year compared to the drought year. We found no clear differentiation between native and exotic species nor grass and forb species for the traits within or across years. Understanding the potential range of these responses enables us to manage plant communities in ways that can mitigate conditions leading to declines in species or even local extirpation.