Potential contributions of the seed rain and seed bank to regeneration of native forest under plantation pine in New Zealand

Abstract

The seed rain, seed bank, and vegetation were studied in a Pinus radiata plantation destined for restoration to native forest, in order to gain information on the vegetation dynamics and potential future vegetation composition of this forest. A total of 1812 ± 245 seeds m^‐2 from 34 species fell in the seed rain between October 1996 and May 1997. The seed bank had a density of 8841 ± 1157 seeds m^‐2, and contained at least 45 species. Alien species contributed 2% of the seedlings and saplings, 6% of the adults, 9% of the seed rain, and 30% of the seed bank, and accounted for 28 of the 69 species identified in this study. As long as disturbance to the forest is minimal, native species can be expected to dominate regeneration. However, only 30 species of seed plants were present as seedlings, saplings, or adults, and several late‐successional native species have become locally extinct. The seed rain is a potential source of recruits for these species (12 of the 34 species found in the seed rain were not present in the vegetation), but some species will need to be actively reintroduced if the forest is to be returned to its pre‐human condition.

Keywords:

• seed rain
• seed bank
• Karori Wildlife Sanctuary
• Pinus radiata plantation
• secondary succession
• forest community dynamics
• alien species
• restoration