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Temperature sensitivity ( Q 10 ) of soil organic carbon (SOC) decomposition is an important index to estimate the dynamics of soil C budget. However, the spatial variation of Q 10 and its influencing factors remain largely uncertain. In this study, we reviewed the effects of climate environment, spatial geographic pattern, soil physicochemical property, vegetation type, microbial community composition and function, and global climate change on Q 10 to summarize the general rule of each factor influencing Q 10 and compare the relative contribution of each factor to Q 10 in different ecosystems. The results showed that Q 10 decreases with the increases of temperature and precipitation, but increases with the rise of latitude and altitude. The Q 10 value is higher in grassland than that in forest, and also in coniferous forest and deciduous forest than that in evergreen broad-leaved forest. Carbon quality is negatively correlated with Q 10 , but the C quality hypothesis is not always valid with exogenous substrate input. For example, the increment of substrate availability may significantly increase Q 10 in low-quality soils. Q 10 decreases with the enhanced proportion of r-strategy microorganisms (Proteobacteria and Ascomycetes), but increases with the enhanced proportion of K-strategy microorganisms (Acidobacteria and Basidiomycetes). Q 10 increases with elevated CO 2 concentration, but declines with atmospheric nitrogen deposition. In natural ecosystems, Q 10 is mainly regulated by temperature and C quality. Temperature is the main factor regulating Q 10 in the topsoil while C quality is the main factor in deep soil. Our review provided a theoretical support to improve the coupled climate-C cycle model and achieved the C neutral strategy under global warming.

In this study, a field experiment was conducted to estimate the effects of simulated nitrogen (N) deposition (low-N: 30 kg N·hm -2 ·a -1 , moderate-N: 60 kg N·hm -2 ·a -1 , high-N: 90 kg N·hm -2 ·a -1 ) on ecological stoichiometry of leaf litter in Moso bamboo forest under conventional management (CM) and intensive management (IM) practices. The results showed that compared with CM, IM significantly increased C, N and P concentrations of leaf litter by 9.3%, 32.4% and 22.7%, respectively, but significantly decreased C:N, C:P and N:P ratios by 17.4%, 54.3% and 44.6%, respectively. In CM Moso bamboo plots, low- and moderate-N deposition significantly increased C, N and P concentrations of leaf litter but decreased C:N, C:P and N:P, high-N deposition significantly increased C, N concentrations, C:P and N:P, but decreased P concentration. In IM Moso bamboo plots, low-N deposition significantly increased P concentration but decreased C concentrations, C:P and N:P, moderate-N deposition significantly increased N and P concentrations but decreased C concentration, C:N, C:P and N:P, high-N deposition significantly increased C:N, C:P and N:P but decreased P concentration. The interaction of management intensity and N deposition significantly influenced stoichiometry of leaf litter, except for C:N. The P concentration of leaf litter was significantly correlated with P concentration in soils.

In this study, a field experiment was conducted using simulated N deposition method in conventionally managed (CM) and intensively managed (IM) Moso bamboo forests to test the responses of five soil enzymes (including β-fructofuranosidase, cellulase, nitrate reductase, hydrogen peroxidase and urease) to simulated N deposition of four treatment levels of 0, 30, 60 and 90 kg N·hm -2 ·a -1 . The results showed that compared with CM, IM significantly increased soil β-fructofuranosidase, cellulase, urease activities by 55.5%, 112.9% and 28.6%, respectively, but significantly decreased nitrate reductase activity by 31.5%, and had no significant effect on hydrogen peroxidase activity. Nitrogen deposition significantly decreased soil β-fructofuranosidase (20.0%-49.4% and 36.2%-45.1%), cellulase (20.5%-46.3% and 18.3%-49.0%), nitrate reductase (67.9%-85.2% and 15.2%-34.2%) activities in both CM and IM plots, respectively, and also urease activity (23.1%-47.6%) in IM, but enhanced the urease activity (8.1%-50.6%) in CM, and had no significant effects on hydrogen peroxidase activity. The combination of N deposition and management types significantly impacted the four soil enzyme activities except for hydrogen peroxidase.

In order to investigate the relationship between the accumulation of phenolic acids in peanut continuous cropping soil and the continuous cropping obstacle of peanut, the effects of p-hydroxy benzoic acid and cinnamic acid on peanut root zone soil nutrients, soil enzyme activities and yield of peanut were studied by pot experiment at three stages of peanut, i.e. the pegging stage of peanut (45 days after seedling), the early podding (75 days after seedling) and the end of podding (105 days after seedling) stages. The results showed that the peanut root zone soil nutrients and enzyme activities changed obviously under the two phenolic acids treatment, especially at the pegging stage of peanut. The soil alkali-hydrolyzable nitrogen, available phosphorus, available potassium, and soil enzyme activities (urease, sucrose, neutral phosphatase) were decreased significantly. At the early and end of podding stages of peanut, the effects of the two phenolic acids on peanut root zone soil nutrients and soil enzyme activities were under a weakening trend. The allelopathy of cinnamic acid was stronger than that of p-hydroxy benzoic acid at the same initial content. The pod yield per pot was reduced by 45.9% and 52.8%, while the pod number of per plant was reduced by 46.2% and 48.9% at higher concentration (80 mg·kg -1 dry soil) of p-hydroxy benzoic acid and cinnamic acid treatments, respectively.

A litterbag experiment was conducted to study the decomposition of Cunninghamia lanceolata leaf litter under ambient and reduced UV-B radiation (22.1% below ambient). Comparing with ambient treatment, the reduced treatment decreased the decomposition rate of C. lanceolata leaf litter by 69.6% (P<0.001), making the relative contents of nitrogen (N), phosphorus (P), and lignin in the litter increased by 150%, 83.3%, and 13.8%, respectively, and the release of potassium (K) and carbon (C) slowed down. In the process of litter decomposition, photo-degradation of lignin didn't play crucial role. The results suggested that UV-B radiation could accelerate the decomposition rate of C. lanceolata leaf litter, promote the release of N, P, K, and C from it, and increase the nutrients turnover rate in litter layer as well as the carbon flux on the ground, giving potential effects on the function of C. lanceolata forest as a carbon source or sink in humid subtropical China.

An investigation was made on the soil seed banks in the logging gaps of Populus davidiana--Betula platyphylla secondary forest, secondary broad-leaved forest, and broad-leaved Korean pine mixed forest at their different succession stages in Changbai Mountains. Among the test forests, secondary broad-leaved forest had the highest individual density (652 ind x m(-2)) in its soil seed bank. With the succession of forest community, the diversity and uniformity of soil seed bank increased, but the dominance decreased. The seed density of climax species such as Pinus koraiensis, Abies nephrolepis, and Acer mono increased, whereas that of Maackia amurensis and Fraxinus mandshurica decreased. Moreover, the similarity in species composition between soil seed bank and the seedlings within logging gaps became higher. The individual density and similarity between soil seed bank and the seedlings in non-logging gaps were similar to those in logging gaps. All of these indicated that soil seed bank provided rich seed resources for forest recovery and succession, and the influence of soil seed bank on seedlings regeneration increased with the succession.

The litters of seven tree species representing the dominant plant species in three main successional stages in subtropical China, i.e., Pinus massoniana in early successional forests, Schima superba and Cinnamanun camphora in transitional forests, and Castanopsis eyeri, Cyclobalanopsis gracilis, Cyclobalanopsis glauca, and Michelia chapensis in late successional forests, were collected, and their decomposition rates were measured with litterbags. The results showed that M. chapensls and C. gracilis had the highest litter decomposition rate (k = 1.12 and 0.89, respectively), followed by C. camphora and S. superba (k = 0.61 and 0.55, respectively), and P. massoniana (k = 0.51), indicating that there was a trend of litter decomposition rate being increased with succession stage. Litter decomposition rate had significant correlations with the litter' s initial P, N, and lignin contents, lignin/N ratio (P < 0.01), and C/N ratio (P < 0.05), suggesting that the initial P, N, and lignin contents and lignin/N ratio of leaf litter could be the good indictors of litter decomposition rate.