Comparison of soil seed banks in canopy gap and closed canopy areas between a secondary natural forest and a big leaf mahogany (Swietenia macrophylla king) plantation in the Mt. Makiling forest reserve, Philippines

We compared soil seed banks between a secondary natural forest and an adjacent big leaf mahogany (Swietenia macrophylla King) plantation in the Mt. Makiling Forest Reserve, Philippines to understand seed bank dynamics, the relationship between soil seed bank and aboveground vegetation and effects of canopy gaps on soil seed banks in a tropical rain forest. Stand inventorying was conducted and soil seed bank composition and density were examined in February and August 2008. Seeds were germinated to identify the species. Aboveground species composition and small canopy gaps little influenced soil seed bank composition and density. Only three species in the secondary natural forest and six species in the big leaf mahogany plantation were commonly found in both soil seed banks and aboveground vegetation. Most species in soil seed banks were pioneer or mid seral species which came from the outside of the stands. The dominant species in soil seed banks were mid seral species in the secondary natural forest and pioneer species in the big leaf mahogany plantation. Differences in soil seed bank composition and density were greater between stands than between gap closure levels, implying little effects of small canopy gaps on soil seed bank composition and density in the study sites. The low soil seed bank density of late seral species suggests that soil seed bank may not be the major source of late seral species regeneration while high soil seed bank density of pioneer and mid seral species implies that soil seed bank can be critical in the regeneration of pioneer and mid seral species in tropical rain forests.