Forest edges benefit adults, but not seedlings, of the mistletoe Alepis flavida (Loranthaceae)

Abstract

1. We tested the hypothesis that different life-history stages of the same plant species show different responses to forest edge and interior environments. We investigated the effects of forest edges on growth, survival and density of seedlings, juveniles and adults of an endemic New Zealand mistletoe, Alepis flavida, over a 5-year period. 2. Rates of establishment and growth were significantly higher for seedlings in forest interior than on forest edges but both juveniles and adults grew significantly faster on forest edges. 3. Mortality rates were greater for juveniles than for adults, but there was no significant difference between forest edge and interior. 4. Densities of seedlings and the larger size class of juvenile plants were significantly greater in the forest interior than on forest edges, whereas densities of the larger size class of adults were significantly greater on edges. 5. Changes in densities over 5 years showed that larger juveniles increased in density only in the forest interior, whereas larger adults increased in density only on forest edges. 6. Thus, seedlings of A. flavida have strong advantages in the forest interior, whereas juveniles and adults grow faster on forest edges. 7. This study emphasizes the need to examine multiple life-history stages in studies of edge effects.