Global change and response of coastal dune plants to the combined effects of increased sand accretion (burial) and nutrient availability

摘要

Coastal dune plants are subjected to natural multiple stresses and vulnerable to global change. Some changes associated\ud\udwith global change could interact in their effects on vegetation. As vegetation plays a fundamental role in building and\ud\udstabilizing dune systems, effective coastal habitat management requires a better understanding of the combined effects of\ud\udsuch changes on plant populations. A manipulative experiment was conducted along a Mediterranean dune system to\ud\udexamine the individual and combined effects of increased sediment accretion (burial) and nitrogen enrichment associated\ud\udwith predicted global change on the performance of young clones of Sporobolus virginicus, a widespread dune stabilizing\ud\udspecies. Increased burial severity resulted in the production of taller but thinner shoots, while nutrient enrichment\ud\udstimulated rhizome production. Nutrient enrichment increased total plant biomass up to moderate burial levels (50% of\ud\udplant height), but it had not effect at the highest burial level (100% of plant height). The effects of such factors on total\ud\udbiomass, shoot biomass and branching were influenced by spatial variation in natural factors at the scale of hundreds of\ud\udmetres. These results indicate that the effects of burial and nutrient enrichment on plant performance were not\ud\udindependent. Their combined effects may not be predicted by knowing the individual effects, at least under the study\ud\udconditions. Under global change scenarios, increased nutrient input could alleviate nutrient stress in S. virginicus, enhancing\ud\udclonal expansion and productivity, but this benefit could be offset by increased sand accretion levels equal or exceeding\ud\ud100% of plant height. Depletion of stored reserves for emerging from sand could increase plant vulnerability to other\ud\udstresses in the long-term. The results emphasize the need to incorporate statistical designs for detecting non-independent\ud\udeffects of multiple changes and adequate spatial replication in future works to anticipate the impact of global change on\ud\uddune ecosystem functioning.\ud\udCitation: