In arid environments, limiting resources can act as filters that modulate plant strategies, and ultimately lead to changes in community structure. The fast-slow plant economics spectrum hypothesis (fs-PES) states that in areas with more water or nutrient availability, plants should exhibit a fast resource acquisition strategy, whereas in resource-poor environments plants should exhibit a slow resource acquisition strategy, which prioritizes conservation of resources over growth. The main objective of this study is to test the generality of the fs-PES in shrub communities of the Atacama Desert distributed along rainfall and nutrients gradients. We characterized different above- and below-ground functional traits of 10 to 15 dominant shrub species in each of four localities along a precipitation gradient (from 14 to 80 mm, 30 years mean; 27° to 30°S) and in four sites with similar climatic conditions, but located in different soil types at the least arid locality (30°S).
Results/Conclusions
In the precipitation gradient, results revealed an inverse pattern of the fs-PES for leaf and stem traits, but not for root traits. As aridity increased, aboveground traits exhibited a shift from a slow to a fast strategy. Root traits, however, did not shift accordingly with our prediction, rather they showed more complex pattern of shift and coordination with above‐ground traits along the gradient. In the nutrient gradient, leaf changes were associated with the fs-PES, shifting from communities with more acquisitive strategies to communities with more conservative strategies with increasing nutrient limitation. No such pattern of co-variation was observed for roots.
The lack of a fs-PES appears to be related to a strong selection pressures imposed by the hyper‐aridity in conjunction with the short growing season, whereas in the nutrient gradient the co-limitation of multiple resources, seems to promote different responses from different root traits. In addition, for both gradients biotic processes can also be important drivers in determining resource acquisition strategies, particularly for below‐ground traits. We highlight the importance of incorporating leaf and root traits to understand how resource limitation and biotic processes shapes plant ecological strategies in desert ecosystems.
Projects FONDECYT 1151020, CONICYT PIA Apoyo CCTE AFB170008, CONICYT Doctoral Fellowships 21140050 & 21150334