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1.
Ruihong Guo Junqiang Zheng Shijie Han Junhui Zhang Mai-He Li 《Journal of Soils and Sediments》2013,13(2):312-324
Purpose
Little is known about the interactive effects of temperature, nitrogen (N) supply, litter quality, and decomposition time on the turnover of carbon (C) and N of forest litter. The objective of this study was to investigate the interactive effects of warming, N addition and tree species on the turnover of C and N during the early decomposition stage of litters in a temperate forest.Materials and methods
A 12-week laboratory incubation experiment was carried out. The leaf litters including two types of broadleaf litters (Quercus mongolica and Tilia amurensis), a needle litter (Pinus koraiensis), and a mixed litter of them were collected from a broad-leaved Korean pine mixed forest ecosystem in northeastern China in September 2009. Nine treatments were conducted using three temperatures (15, 25, and 35 °C) combined with three doses of N addition (equal to 0, 75, and 150 kg?·?ha?1?a?1, respectively, as NH4NO3).Results and discussion
After 12 weeks of incubation, the mass loss ranged between 12 and 35 %. The broadleaf litters had greater mass loss and cumulative CO2–C emission than the needle litter. Temperature and N availability interacted to affect litter mass loss and decomposition rate. The dissolved organic carbon (DOC) and nitrogen (DON) concentrations in litter leachate varied widely with litter types. DOC increased significantly with increased temperature but decreased significantly with increased N availability. DON increased significantly with increased N availability but showed a higher level at the moderate decomposition temperature. The amounts of CO2 and N2O emission were significantly higher at 25 °C than those at 15 and 35 °C, and were significantly increased by the N addition.Conclusions
The present study indicated relatively intricate temperature and N addition effects on C and N cycling during early stages of litter decomposition, implying that future increases in temperature and N deposition will directly affect C and N cycling in broad-leaved Korean pine mixed forest ecosystem, and may indirectly influence the ecosystem composition, productivity, and functioning in NE China. It is, therefore, important to understand the interactive effects of biotic and abiotic factors on litter decomposition in field conditions in order to assess and predict future ecosystem responses to environmental changes in NE China. 相似文献2.
The aim was to quantify medium term litter type and litter mixture effects on the translocation and transformation dynamics of root and leaf litter C during decomposition. Partitioning of 13C-labeled root or leaf litter C (beech – Fagus sylvatica L., ash – Fraxinus excelsior L.) to CO2, water-extractable organic C (WEOC), microbial biomass C (CMB) and light (LF) and heavy soil fraction (HF) was determined in a laboratory decomposition experiment of 206 days. The proportions of C mineralized from ash leaf (34%) and root litter (29%) were higher than those from beech leaf (24%) and root litter (23%). In mixture with beech, the mineralization of ash leaf litter was enhanced. Mineralization was positively correlated with litter-derived WEOC until day 29. Water-extractable organic C declined with time, until <0.1% of litter C remained in this fraction. Litter-C recovery in CMB was higher for ash (0.7–1.0%) than for beech (0.2–0.4%). The litter C recovery in HF (4–12%) was positively correlated with that in WEOC (days 9 and 29) and CMB, but did not differ between treatments. Ash leaf litter mineralization showed different behavior in mixed treatments from pure treatments. Thus, the ability to transfer results from pure to mixed treatments is limited. The litter differed in chemical composition and in mineralization dynamics, but differences in partitioning to HF, WEOC and MB were finally of minor importance. 相似文献
3.
Medicago littoralis leaf material, labelled with 14C and 15N, and of C:N ratio 8.7:1, decomposed rapidly in a calcareous soil. One half of the plant-C and two thirds of the plant-N remained in the soil as organic residues after 34 days. The rates of decomposition and the changes in the distribution of organic-14C and -15N residues followed similar patterns.Incorporation of 14C and 15N into microbial cells, formed during plant breakdown, reached a maximum after 62 days. At this time the microbial biomass accounted for 21.9 and 23.3%, respectively, of residual organic-14C and -15N. Thereafter, the amounts of isotope-labelled biomass decreased with the percentage decrease slightly exceeding that of the total labelled soil residues.During plant decomposition, changes occurred in the concentrations of organic-14C and -15N in some of the soil components, these having been fractionated according to density and particle size. Especially evident was the rapid and extensive decrease of labelled material from the fine clay-size components. This was partly due to the decrease in the biomass-14C of this fraction. Changes in biomass-14C of some physical fractions were approximately reflected by changes in their numbers of viable microorganisms. 相似文献
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