Do primary rainforest tree species recruit into passively and actively restored tropical rainforest?

Background

In many restoration projects, recruitment is dominated by a low diversity of regionally-abundant pioneer species and species with small, easily dispersed seeds. These species are characteristic of secondary rainforest and do not include the far more diverse suite of species characteristic of the original, primary rainforest. As restoring ecosystem processes is one of the central goals of restoration, this raises the question of which, if any, of the available rainforest restoration methods may be used to promote the recruitment of primary rainforest species.

Goals and methods

The main goals of this paper are to investigate the recruitment of primary rainforest species in older restoration sites, compare the patterns of species composition between older and younger recruits, evaluate the similarity of the functional group composition of recruited individuals to that of old-growth rainforest, secondary rainforest, or the originally planted species, and assess the effectiveness of different restoration treatments in promoting the recruitment of species from old-growth rainforest.

conclusions and Takeaways

Recruitment of primary rainforest species in older restoration sites is negligible, and the recruitment of pioneer species with small, biotically-dispersed diaspores dominates the restored rainforest. The study also found that none of the restoration methods tested have so far encouraged the recruitment of species from primary rainforest over the first 25 years of restoration. The paper highlights the need for ongoing management intervention to increase the diversity of old-growth, interior rainforest species in restored forests.