[Seasonal dynamics of soil labile nitrogen pools and net nitrogen mineralization in subalpine forests along an elevational gradient in western Sichuan, China].
The seasonal dynamics of soil labile nitrogen pools and net nitrogen mineralization of three subalpine forests along an elevation gradient (3600, 3300 and 3000 m), western Sichuan, China were examined. Obvious seasonal dynamics were found in soil labile nitrogen pools (ammonium, nitrate, microbial biomass nitrogen and dissolved organic nitrogen) and net nitrogen mineralization rate, but the seasonality varied with the measured nitrogen pools. The concentrations of soil nitrate (8.38-89.60 mg x kg(-1)) were significantly higher than those of ammonium (0.44-8.43 mg x kg(-1)) in four sampling periods (non-growing season, early, middle and late growing season). Regardless of the elevation, the rate of soil net nitrogen mineralization was negative (-0.77 to -0.56 mg x kg(-1) x d(-1)) early in the growing season, but positive in the other three periods. Except for nitrate, the contents of ammonium, microbial biomass nitrogen and dissolved organic nitrogen varied significantly with elevation and the altitude effects on those pools were dependent on seasons. In summary, soil nitrification was the major process of net soil nitrogen mineralization and soil nitrogen mineralization was not affected by elevational gradient. Soil nitrogen mineralization (0.42-0.99 mg x kg(-1) x d(-1)) in winter was considerable in this area. Relatively high inorganic nitrogen in early spring might be favorable for vegetation growth, but might also be lost from soil ecosystem through leaching.
Rui
R
Yin
Zhen-Feng
ZF
Xu
Fu-Zhong
FZ
Wu
Wan-Qin
WQ
Yang
Li
L
Xiong
Sa
S
Xiao
Zhi-Liang
ZL
Ma
Zhi-Ping
ZP
Li
D018533:Biomass; D002681:China; D065928:Forests; D009584:Nitrogen / Q000032:analysis*; D058458:Nitrogen Cycle; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
D012987:Soil; D009584:Nitrogen