Comparative demography of three coexisting Acer species in gaps and under closed canopy

Abstract

Questions: 1. Is there a trade-off between gap dependency and shade tolerance in each of the life-history stages of three closely related, coexisting species, Acer amoenum (Aa), A. mono (Am) and A. rufinerve (Ar)? 2. If not, what differences in life-history traits contribute to the coexistence of these non-pioneer species? Location: Ogawa Forest Reserve, a remnant (98 ha), speciesrich, temperate deciduous forest in central Japan (36°56' N, 140°35' E, 600 -660 m a.s.l.). Methods: We estimated the demographic parameters (survival, growth rate and fecundity) by stage of each species growing in gaps and under closed canopy through observations of a 6-ha permanent plot over 12 years. Population dynamics were analysed with stage-based matrix models including gap dynamics. Results: All of the species showed high seedling and sapling survival rates under closed canopies. However, demographic parameters for each growth stage in gaps and under closed canopies revealed inter-specific differences and ontogenetic shifts. The trade-off between survival in the shade and growth in gaps was detected only at the small sapling stage (height < 30 cm), and Ar had the highest growth rate both in the shade and in the gaps at most life stages. Conclusions: Inter-specific differences and ontogenetic shifts in light requirements with life-form differences may contribute to the coexistence of the Acer species in old-growth forests, with Aa considered a long-lived sub-canopy tree, Am a long-lived canopy tree, and Ar a short-lived, 'gap-phase' sub-canopy tree.Nomenclature: Satake et al. (1989).Abbreviations: Aa = Acer amoenum; Adt1/Adt2 = Adult stages 1 & 2; Am = A. mono; Ar = A. rufinerve; Fadt1/2 = Female stages 1, 2; Juv1/2 = Juvenile stages 1, 2; Madt1/2 = Male stages 1, 2; Sapl = Large sapling; Saps = Small sapling; Sdl = Seedling.

Response to canopy opening does not act as a filter to Fagus sylvatica and Acer sp. advance regeneration in a mixed temperate forest

“…Under a closed canopy, the four species had very similar growth-size relationships, showing that the differences observed in their social status within the persistent seedling bank do not originate from interspecific differences in height or diameter growth under low light conditions. Many studies have suggested that the differences observed in the social status of the four species may have originated in inter-specific differences in survival rates under closed canopy (Tanaka et al, 2008) and, more specifically, in differences in the relationship between survival rate and seedling size. This relationship may strongly vary among species, leading to interspecific differences in maximum seedling height observed under low light conditions (Kubota et al, 1994;Messier et al, 1999).…”

Analysis of the disassortative mating pattern in a heterodichogamous plant, Acer mono Maxim. using microsatellite markers

“…Acer mono Maxim is one of the major components of Japan's cool-temperate forest (Tanaka et al 2008), and is also known to exhibit heterodichogamy of this type (Mitigami et al 1989;Shibata et al in press). In this study, we examined the mating pattern of A. mono in a natural forest stand by observing the possible factors that could affect the mating pattern, such as flowering morph of heterodichogamy, flowering phenology, flower production, and mating distance.…”

Population structure of woody plants in the arid cloud forests of Dhofar, southern Oman

“…In addition, fluctuation in the availability of water from the short, wet, monsoon season to the long dry season may cause a variable input of new seedlings to the population each year (SHALTOUT and AYYAD 1988). Regarding the gaps, once vegetation is degraded, it becomes more difficult to re-establish due to a reduced level of filtered precipitation by trees, which creates an unbalance in the availability of water (HUSTON 1986, GHAZANFAR 1998, MASAKI et al 1992, TANAKA et al 2008. Moreover, mature trees change the conditions within their own microsite, which affects the establishment of the same or other species (WILSON and AGNEW 1992) and thus the distribution of saplings is spatially associated with canopy crowns (either conspecific or heterospecific).…”

“…This steady replacement of the common and endemic woody trees and shrubs typical of the wet cloud forest is well illustrated by the case of Anogeissus dhofarica (a closed canopy species) which exhibited a J-shaped distribution towards larger individuals in all habitats of the wadi, tending to indicate a declining population with limited regeneration capacity or higher mortality of young individuals. (NARUKAWA and YAMAMOTO 2002, EL-SHEIKH 2005, COOMES and ALLEN 2007, TANAKA et al 2008). …”

“…In the forests of northern Oman, for example, FISHER and GRANDER (1995) have identified variations in the population size and regeneration of juniper woodlands as being affected by the microclimate, topography and hydrology of the area. In addition to these environmental and climatological factors, however, human activities (primarily over-grazing by livestock and related disturbances) are one of the principal influences on woodland species (OLIVER 1980, AGREN and ZACH-RISSON 1990, SKARPE 1990, STEWART and ROSE 1990, WELDEN et al 1991, VEBLEN 1992, SAKIO 1997, LYKKE 1998, SAKIO et al 2002, TANAKA et al 2008.…”