Comparative study of additive basal area of conifers in forest ecosystems along elevational gradients

Abstract

We examined the basal area of two life forms (conifers vs. broadleaf trees) along elevational gradients on Yakushima Island, Japan and on two series of geological substrate on Mount Kinabalu, Borneo. On Yakushima, total stand basal area abruptly increased from 700 to 1,050 m in accordance with the high dominance of conifers, indicating the presence of additive basal area of conifers in conifer-broadleaf mixed forests at higher elevations (1,050-1,300 m). Along two substrate series on Kinabalu, some forests at higher elevations (1,860-3,080 m) showed relatively high dominance of conifers, but conifer basal area did not appear to be additive. Conifers were emergents above the canopy of broadleaf trees in mixed forests on Yakushima, but two life forms usually coexisted in the single-story canopy in mixed forests on Kinabalu. Litterfall rate as a surrogate of productivity decreased with decreasing temperature along elevation on both the sites, but the rate of decrease was slower on Yakushima, where mixed forests at higher elevations showed relatively high rates. Thus, we suggest that additive basal area of conifers was linked to their emergent status, and that it enhanced productivity by complementary use of light by two life forms that occupy different stories. On Yakushima, typhoons are a major disturbance, but do not severely limit the height growth of conifers, allowing the development of twostory mixed forests. On Kinabalu, a major disturbance is El Nin˜o-driven drought, and hydraulic limitation to tree height may explain the non-additive and non-emergent nature of conifers.

Aboveground productivity of an unsuccessful 140-year-old Cryptomeria japonica plantation in northern Kyushu, Japan

“…This suggested a competitive relationship and/or spatial segregation between C. japonica and the broadleaved trees. In C. japonica and broad-leaved mixed forests on Yakushima Island, the additive basal area of C. japonica increased stand-level litterfall production (Aiba et al 2007). They proposed that the emergent status of C. japonica above the canopy of the broad-leaved trees contributed to additive basal area of mixed forests compared with broad-leaved forests.…”

“…In abandoned, unsuccessful conifer plantations, broad-leaved trees often regenerate naturally, resulting in a mixed conifer-broadleaf forest (Imada et al 1991;Hasegawa and Taira 2000;Masaki et al 2004;Kodani 2006). In natural, mixed conifer-broadleaf forests, stand basal area tends to be greater than that of forests comprising only broadleaved trees (Midgley et al 2002;Aiba et al 2007). This suggests that, although the unsuccessful plantations may be unsuitable for timber production, stand productivity may not be low.…”

Effects of Food Type and Number of Feeding Sites in a Tree on Aggression During Feeding in Wild Macaca fuscata

“…However, the plot size was too large to be feasible. Tree species diversity in temperate forests is much lower than that in tropical forests (Takyu et al 2005), and species composition, basal area, and primary production in this plot do not vary considerably from those in other plots in the same altitudinal zone in Yakushima (Aiba et al 2007). Seasonal variations in fruit availability in the plot clearly explained the variations in diet and activity budget of this group (Hanya 2004a, b).…”

Impact of anthropogenic disturbance on the density and activity pattern of deer evaluated with respect to spatial scale-dependency

“…Deer on this island mainly depend on leaves, fruits and seeds of broad-leaved plants for food (Takatsuki, 1990), which they obtain largely from the forest litter . In Yakushima, productivity of litter fall and fruits in broad-leaved forests are higher than those in mixed forests or coniferous plantations (Aiba et al, 2007;Hanya and Aiba, 2010;Hanya et al, 2005). Thus, broad-leaved forest should primarily support the deer population in this island.…”