Influence of forest composition on tree seed predation and rodent responses : a comparison of monodominant and mixed temperate forests in Japan

摘要: Plants often suffer heavy mortality in their seed and seedling stages. While some vertebrates play a significant role dispersal, others are predators of seeds seedlings. In many large-seeded, nutbearing trees, rodents responsible both for effective dispersal by vigorous activity hoarding (Vander Wall, 2001), early-stage through predation (Crawley, 2000; Kitajima Fenner, Hulme Benkman, 2002). Rodents pivotal the regeneration demography large-seeded trees. Conversely, trees can affect rodent populations. Large high quality food resource but they not reliable foods because exhibit large interannual variations production (Kelly, 1994; Vander 2001). The annual variation crops (e.g. masting followed low subsequent years) has major influence on population size predators, such that increases after decreases during seed-crop years (Wolff, 1996b; Wright et al., 1999; Ostfeld Keesing, 2000). Variation numbers may turn 2002; Zhang Chapter 16, this volume). Ingestion have negative effects physiology; seeds, especially Quercus acorns Aesculus contain secondary compounds which operate as chemical defence against 2001; Shimada Saitoh, 2003). interaction between populations been intensively studied Crawley, Hulme, Kollmann, 2, volume, references therein). ecological significance is supposedly synchronous satiates andso produces disproportionately cohort seedlings following (Janzen, 1971; Kelly, 1994). However, polyphagous generalist (Hulme