Increased resource availability prevents the disruption of key ecological interactions in disturbed habitats

Abstract

Anthropogenic disturbance can modify habitat structure and resource availability, potentially disrupting ecological interactions. This issue may be critical for pollination and seed dispersal, which determine natural regeneration. The mistletoe Tristerix corymbosus is almost exclusively pollinated by a hummingbird (Sephanoides sephaniodes) and dispersed by a marsupial (Dromiciops gliroides). We examined the extent to which human-induced habitat change and resource availability influence the interaction rate of this plant-pollinator-seed disperser system, along a forest transformation gradient (from native forest to exotic plantations). We estimated visitation rates of S. sephaniodes and D. gliroides on 70 T. corymbosus mistletoes using camera traps. We related visitation rates to habitat structural features and resource availability (flowers and fruits of the mistletoe and the neighborhood) using spatially explicit models. Sephanoides sephaniodes and D. gliroides visitation rates responded positively to shrub and bamboo cover, moss abundance, and mistletoe spatial arrangement. Pollination and seed dispersal interactions were sensitive to the flower and fleshy-fruit neighborhoods, being variable across months. Further, D. gliroides showed a non-random spatial association with fleshy-fruited plants. A larger sunlight incidence on disturbed habitats may prevent the disruption of key ecological interactions by increasing resource availability. This effect would result from the presence of shade-intolerant plants, which are benefited by sunlight exposure. Patches of disturbed habitat may enhance landscape heterogeneity, providing complementary resources to the native remnants.