Soil legacies determine the resistance of an experimental plant-soil system to drought

This study examines the effects of climate and the degree of forest fragmentation legacies on response of oak to drought. A microcosm approach was set up with holm oak seedlings from three provenances grown in soils coming from two regions of contrasting climate (drier vs. wetter), and three scenarios of forest fragmentation (low, mid, and high agricultural matrix influence). We measured different indicators of the plant-soil system functioning such as ecosystem respiration, net ecosystem exchange, gross primary productivity, stomatal conductance, quantum yield, biomass allocation, and mycorrhization. Legacies of the bioclimatic region and the degree of forest fragmentation on soil properties drove the response to drought of an experimental plant-soil system, masking the effects of seedling provenance. The system was functionally more resistant to drought in soils from forest fragments with more agricultural influence and from the drier region. Our results indicate that the degree of forest fragmentation and bioclimatic legacies on soil properties exerted a much more decisive effect on the response of the plant-soil system to drought than holm-oak seedling provenance.This work was supported by the Spanish Ministry for Economy and Competitiveness (MINECO) with the projects VULGLO (grant number CGL2010 22180 C03 03), VERONICA (grant number CGL2013-42271-P) and MyFUNCO (grant number CGL2011-29585-C02-02), and by the Comunidad de Madrid with the project REMEDINAL 3-CM (grant number S2013/MAE-2719). DFR held a pre-doctoral fellowship awarded by the Mexican Council of Science and Technology (CONACyT, grant number 310849).Peer Reviewe