排序方式: 共有2条查询结果,搜索用时 15 毫秒
1
1.
Seasonal variation in oxygen isotope composition of waters for a montane larch forest in Mongolia 总被引:2,自引:0,他引:2
Sheng-Gong Li Maki Tsujimura Atsuko Sugimoto Lisa Sasaki Tsutomu Yamanaka Gombo Davaa Dambaravjaa Oyunbaatar Michiaki Sugita 《Trees - Structure and Function》2006,20(1):122-130
Measurements of water oxygen isotopic composition were conducted in the 2003 growing season for a montane larch (Larix sibirica Ledeb.) forest in northern Mongolia, a transitional area from the south Siberian taiga to the Asian steppe. Oxygen isotopic
composition of foliar water and its daily variability were found to be sensitive to atmospheric evaporative demand. During
most of the growing season, water sources used by larch trees were from the upper 30-cm surface layer of the soil when precipitation
input was large, and were from the deeper layer when the water supply at the upper soil layer was limited. The Keeling plot
method suggested that the forest returned soil water to the atmosphere predominantly by means of canopy transpiration during
the peak growth period (in August). 相似文献
2.
Sheng-Gong Li Maki Tsujimura Atsuko Sugimoto Gombo Davaa Dambaravjaa Oyunbaatar Michiaki Sugita 《Trees - Structure and Function》2007,21(4):479-490
This paper reports the temporal variation (2002–2004) in foliar δ13C values, which are indicative of long-term integrated photosynthetic and water use characteristics, of Siberian larch (Larix sibirica Ledeb.) trees in a montane forest at Mongonmorit, NE Mongolia. At the stand, the δ13C value for understory shaded leaves was more negative by 2‰ on average than that for sunlit leaves sampled concurrently from
open and sun-exposed environments in a forest gap. The δ13C value of both sunlit and shaded leaves showed pronounced intra- but relatively small inter-seasonal variations. The δ13C value was more positive for juvenile than mature leaves. We conjecture that juvenile leaves may derive carbon reserves in
woody tissues (e.g., stems). Regardless of leaf habitats, the δ13C value was also affected by insect herbivores occurred in mid summer of 2003, being more negative in newly emerging leaves
from the twigs after defoliation than in non-defoliated mature leaves. This pattern seems to contrast with that for the juvenile
leaves in the early growing season. We surmise that the newly emerging leaves used stored organic carbon that was depleted
due to fractionation during remobilization and translocation for leaf regrowth. There was also intra- and inter-seasonal variation
in the foliar N concentrations and C:N ratios. A good positive (negative) correlation between the foliar δ13C values and N concentrations (C:N ratios) was also observed for both sunlit and shaded leaves, suggesting that the relationship
between water and nitrogen use is a crucial factor affecting the plant carbon–water relationship in this mid latitude forest
with a cold semiarid climate. Our isotopic data demonstrate that the larches in NE Mongolia exhibits relatively higher water
use efficiency with a distinct within-season variability. 相似文献
1