Colonization of agricultural windbreaks by forest trees: Effects of connectivity and remnant trees

Planted agricultural windbreaks may provide habitat for forest tree species and facilitate forest regeneration within the agricultural landscape, if the windbreaks are colonized by forest trees. In order to examine the potential for windbreaks to foster forest regeneration, I surveyed the understories of 51 windbreaks in Monteverde, Costa Pica, for forest tree seedlings. The windbreaks had been planted 5-6 yr earlier. Ninety-one forest tree species (including both primary and secondary forest species) were found in the windbreaks; however, many of the species occurred in low densities. The mean density of forest tree seedlings in the windbreaks was 2.14 seedlings/m(2). Landscape factors appeared to have important effects on tree recruitment patterns. Windbreaks that were connected to forest had significantly higher densities of forest tree seedlings and greater numbers of forest tree species in their understories than windbreaks that were not connected to forest. In particular, connected windbreaks had higher densities and more species of bird-dispersed trees than nonconnected windbreaks. These differences probably reflect the greater activity of frugivorous birds within connected windbreaks and the resulting higher input of forest tree seeds. Windbreaks with remnant forest trees had significantly higher densities of forest tree seedlings of other species and more forest tree species than windbreaks lacking remnant trees. By serving as habitats for forest tree species, windbreaks may contribute to the maintenance of forest trees within agricultural landscapes and serve as tools for forest restoration in the tropics.