Birds as mediators of passive restoration during early post-fire recovery

Abstract

Remnant trees or artificial perches in burned areas can favor passive restoration through the perch effect. Birds consuming fruits in remnant vegetation patches or unburned adjacent communities are expected to defecate or regurgitate seeds as they perch on standing burned trees and shrubs in post-fire areas. The purpose of this study was to determine whether standing burned trees and shrubs are used by frugivorous birds as perching structures and if their maintenance promotes passive restoration of burned ecosystems. We: (a) recorded the seed rain of woody species in microsites underneath perches and in the open, (b) recorded seedling survival underneath the canopy of resprouting individuals and in the open, and (c) quantified seed rain and seedling recruitment of endozoochorous species at hectare level. Standing burned trees and shrubs were used as natural perches by frugivorous birds and increased seed arrival into recently burned communities. In addition, seedling survival was greater below the canopy of resprouting woody vegetation than in the open. Thus, standing burned trees and shrubs provide an important structural component attracting frugivorous birds, and therefore seeds during early post-fire regeneration. Resprouting trees and shrubs were also critical during post-fire recovery, because they act as seed traps, facilitate seedling survival and produce fruits that attract frugivorous birds, promoting seed flow among different communities at a landscape level. Therefore, the maintenance of standing burned woody vegetation could favor passive restoration of burned areas.