Spatial and Seasonal Patterns of Seed Dissemination of Cornus Controversa in a Temperate Forest

Abstract

Seasonal and spatial patterns of seed dissemination of the canopy tree Cornus controversa were studied over two fruiting seasons in a temperate deciduous forest in Japan. Seedfall was monitored every 2 wk in seed traps (N = 221) distributed over a 1-ha study plot that included 12 mature Cornus. Estimated annual seed production was 1.57 x 10 6 seeds/ha. In both years, the peak of fruit ripening had already ended before migratory frugivorous birds entered the area and only 17% of the seeds were disseminated by birds. Directly fallen seeds were deposited close to the parent trees (usually within 10m, infrequently as far as 35 m from parent trees). In contrast, bird-disseminated seeds showed a markedly scattered distribution; the birds deposited more than half of the seeds they ate > 5 m from the crown edge, and density ofbird-disseminated seeds exceeded that of directly fallen seeds at distances > 15 m, with some found > 40 m from the nearest mature Cornus.In addition, birds seemed to selectively eat fruits that contained viable seeds. The density of bird-disseminated seed decreased significantly with increasing distance from fruiting trees, both conspecific and heterospecific. Distance to the nearest edge of canopy gaps that were several years old had little effect on the spatial pattern ofbird-disseminated seeds. This means that seeds of C. controversa were not directionally dispersed into canopy gaps by birds.

Spatial distribution patterns of trees at different life stages in a warm temperate forest

“…After acorns drop, rodents may hoard sound acorns in the soil after transporting them for distances <20 m, so acorn species may benefit from such seedling establishment (Yasuda et al 2000;Sone et al 2002). Seed dispersal by birds and/or mammals also shows aggregation (Masaki et al 1994;Dominy and Duncan 2005). Secondary dispersal of seeds in feces by dung beetles and rodents reduces seed aggregations (Shepherd and Chapman 1998;Andresen 2001Andresen , 2002.…”

Colonization of fleshy-fruited plants beneath perch plant species that bear fleshy fruit

“…Spatial distributions of bird-dispersed seed rain and saplings are affected by spatial distributions and abundances of perch plant species (Herrera 1984;Hoppes 1988;Murray 1988;Willson and Crome 1989;Alvarez-Buylla and Martínez-Ramos 1990;Izhaki et al 1991;Debussche and Isenmann 1994;Herrera et al 1994;Masaki et al 1994;Kominami et al 1998). In particular, the perch plants of C. japonica and N. sericea, which exhibit higher numbers of bird-dispersed seeds and saplings, would compose a heterogeneous vegetation structure, and also homogenize population structure beneath them due to the similarity in quantitative seed and sapling compositions.…”

“…Frugivorous birds feed on fruits and defecate or regurgitate seeds near the fleshy-fruited plants on which they feed and perch (Fleming and Heithaus 1981;Glyphis et al 1981;Debussche et al 1982;Uhl et al 1982;Guevara et al 1986;Sallabanks 1992;Guevara and Laborde 1993;Willson 1993;Kollmann and Pirl 1995;Alcántara et al 2000a). This birddispersed seed rain depends on the fruiting environment (Herrera 1986), e.g., both spacing among and crop yield of fleshy-fruited perch plants (Herrera 1984;Hoppes 1988;Murray 1988;Willson and Crome 1989;Alvarez-Buylla and Martínez-Ramos 1990;Izhaki et al 1991;Debussche and Isenmann 1994;Herrera et al 1994;Masaki et al 1994;Kominami et al 1998). In particular, perch plants with fleshy fruits attract more birds, and therefore attract more bird-dispersed seeds, than those without fleshy fruits (Uhl et al 1982;Guevara et al 1986;Robinson & Handel 1993;Toh et al 1999).…”

Fleshy fruit characteristics in a temperate deciduous forest of Japan: how unique are they?

“…In Japan, there are Japanese macaque (Macaca fuscata) and Asiatic black bear (Ohdachi et al 2009), and they often disperse seeds of trees as efficiently (Koike 2009;Koike et al , 2010Otani 2003;Otani and Shibata 2000;Takahashi et al 2008) as frugivorous birds (Kominami et al 2003;Masaki et al 1994;Takahashi and Kamitani 2004). Therefore, we are able to test more directly how variation in fruit characteristics among tree species is related to dispersal by either birds or large arboreal mammals.…”