[Responses of soil microbial carbon use efficiency to short-term nitrogen addition in forest].

As an important parameter regulating soil carbon mineralization, microbial carbon use efficiency (CUE) is essential for the understanding of carbon (C) cycle in terrestrial ecosystems. Three nitrogen supplemental levels, including control (0 kg N·hm·a), low nitrogen (40 kg N·hm·a), and high nitrogen (80 kg N·hm·a), were set up in a forest in the Daiyun Mountain. The basic physical and chemical properties, organic carbon fractions, microbial biomass, and enzyme activities of the soil surface layer (0-10 cm) were measured.

[Effects of nitrogen addition on the kinetic parameters of soil acid phosphomonoesterase in a Moso bamboo forest].

Soil phosphatases are important in the mineralization of organophosphates and in the phosphorus (P) cycle. The kinetic mechanisms of phosphatases in response to nitrogen (N) deposition remain unclear. We carried out a field experiment with four different concentrations of N: 0 g N·hm·a(control), 20 g N·hm·a(low N), 40 g N·hm·a(medium N), and 80 g N·hm·a(high N) in a subtropical Moso bamboo forest.

[Effects of management on the content and spectral characteristics of soil dissolved organic carbon in a subtropical forest].

The differences of artificial measures, such as logging residue management, between assisted natural regeneration and afforestation may change the content and structure of soil dissolved organic carbon (DOC) and affect forest carbon cycle. In this study, we investigated the effects of managements on the content and spectral characteristics of DOC in a subtropical forest, which contained the forest of assisted natural regeneration (Ⅱ), and the plantation (Ⅲ), both were converted from mature secondary forests (Ⅰ). Results showed that DOC content in the 0-10 cm soil layer was significantly decreased by 21% and 50% in Ⅱ and Ⅲ, respectively, compared with that in Ⅰ.

[Soil enzyme stoichiometry revealed the changes of soil microbial carbon and phosphorus limitation along an elevational gradient in a forest of Wuyi Mountains, Southeast China].

Understanding changes in soil enzyme activities and ecoenzymatic stoichiometry is important for assessing soil nutrient availability and microbial nutrient limitation in mountain ecosystems. However, the variations of soil microbial nutrient limitation across elevational gradients and its driving factors in subtropical mountain forests are still unclear. In this study, we measured soil properties, microbial biomass, and enzyme activities related to carbon (C), nitrogen (N), and phosphorus (P) cycling in forests at different altitudes of Wuyi Mountains.

Enzyme stoichiometry evidence revealed that five years nitrogen addition exacerbated the carbon and phosphorus limitation of soil microorganisms in a forest.

The activity and stoichiometry of soil extracellular enzyme can provide a good indication for changes in soil nutrient availability and microbial demands for nutrients. However, it remains unclear how would nitrogen (N) deposition affect nutrient limitation of microbes in subtropical forest soils. We conducted a 5 years N addition experiment in a subtropical forest.

[Responses of soil phosphorus fractions and microorganisms to nitrogen application in a subtropical Phyllostachys pubescen forest].

Phosphorus (P) is an important nutrient for plant and microbial growth. Soil P availabi-lity is poor in subtropical areas. Long-term heavy nitrogen (N) deposition might further reduce P availability.

[Effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter in soil in Moso bamboo plantations.].

The subtropical zone in China is one of the regions most affected by nitrogen deposition. Soil dissolved organic matter (DOM) is considered to be an important indicator of soil organic matter. Nitrogen deposition may alter the quality and quantity of soil DOM by changing soil microbial activity.

[Nutrient and metabolic responses of the leaves of Cunninghamia lanceolata seedlings to warming and reduced precipitation in different season].

We examined the effects of warming (+5 ℃) and reduced natural precipitation (-50%) on nutrient status and physiological indices of Cunninghamia lanceolata seedlings during winter and summer in subtropical China. The results showed that seasonal changes in temperature and precipitation caused the seasonal differences in plant nutrient contents and metabolites levels. Contents of carbon, nitrogen, phosphorus, and potassium in leaves in winter were significantly higher than those in summer.

Effects of soil warming on soil microbial extracellular enzyme activities with different depths in a young Chinese fir (Cunninghamia lanceolata)plantation of subtropics.

Extracellular enzyme activitie (EEAs) are a sensitive indicator of microbial function and soil organic matter decomposition in response to climate warming. Up to now, most studies of climate warming and their effects on EEAs have been restricted on the relatively carbon rich topsoil (the upper 20 cm of the soil), whereas little is known about EEAs in subsoil (below 30 cm depth). This study focused on the responses of EEAs to soil warming in a subtropical forest at depths of 0-10 cm, 10-20 cm, 20-40 cm and 40-60 cm.

[Effects of precipitation reduction on the composition and stability of soil organic matter in a young Cunninghamia lanceolata plantation.].

It is hard to predict the response of soil organic matter (SOM) to global climate change due to its heterogenous chemical structure. With the development of molecular techniques to identify the structure, sources and stages of SOM degradation, long-standing questions regarding the composition and stability of SOM might be resolved. To investigate the effects of changes in precipitation patterns on the stability of SOM, we analyzed the specific compositions and extent of degradation of SOM using biomarkers, in a young Cunninghamia lanceolata plantation after reducing 50% of precipitation (P) for two years.