资源环境科技发展态势分析平台

Tropical dry forests (TDFs) on the Pacific Coast of Mexico experience seasonal droughts and very infrequent direct hurricane disturbance. Over a 4-year period, two hurricanes made landfall in the Chamela-Cuixmala Biosphere Reserve, Hurricane Jova (category 2) in October 2011 and Hurricane Patricia (category 4) in October 2015. Our permanent long-term watershed-scale research program in the reserve provided a unique opportunity to analyze the ecosystem response to these hydrometeorological extreme events. Since 1982, we have been collecting monthly litterfall samples in 120 litter traps across five small contiguous watersheds. A direct instantaneous effect of both hurricanes was a massive deposition of green and senescent leaves, and fine woody debris to the forest floor. Hurricane-month litterfall flux largely exceeded the amount produced in any month of the pre-disturbance period (1982-2010), suggesting low resistance to hurricanes. Post-Jova recovery was fast, a response likely explained by a combination of the unusually high dry-season precipitation and higher than average total annual precipitation, coupled to a large flux of P-enriched litter and the re-sprouting response of many TDF species. Annual litterfall the year following Patricia decreased to half of that during the hurricane year, concomitant with a decrease in annual rainfall 20% below average. Ecosystem resilience seems strongly linked to post-disturbance water availability. Therefore, drought after a hurricane may limit the capacity of tropical dry forests to rapidly recover. The implications of these climate-related disturbances for forest recovery and management are discussed.