Seed bank responses after clearcutting Pinus patula plantations in Andean high montane areas

Abstract

Clearcutting exotic plantations favours natural regeneration processes in which seed banks may play an important role. In Andean high montane areas, after Pinus patula clearcutting, changes in soil pH and litter lead to increased fauna and flora biodiversity. However, the impact of these changes on seed banks remains unknown. The aims of the present study were to understand how seed bank richness, abundance, and composition changes after P. patula clearcutting, and to identify the role of aboveground cover, pH and litter cover on these seed bank variations. The study was conducted in three areas with different post-clearcutting ages (0, 2.5, 4.5 years), a P. patula plantation and in a high Andean forest patch. All these sites were located between 3 033 and 3 100 m.a.s.l. Seed bank abundance, richness and the number of seeds of the ten most abundant species increased in areas with 2.5 and 4.5 years after clearcutting. Moreover, seed bank composition was different among study areas. These changes were related to increasing aboveground vegetation cover and soil pH, and to decreasing litter cover. Seed banks contributed almost exclusively to the recovery of some herbaceous species; we recorded only one tree species recruit from the seed banks (Baccharis latifolia) in the forest soils; therefore, the natural regeneration processes may be constrained. Our results highlight the need to implement active restoration to accelerate high montane forest recovery in areas previously covered with pine tree plantations.