In order to investigate soil seasonal gleization process in the alpine meadow on the Tibetan plateau, the soil gleization and its two main controls (high soil organic carbon content (SOC) content and anaerobic environment) were reported in the alpine grassland from Dec. 2013 to March 2014. The results show that the soil seasonal gleization occurres in the humus layer with blue-gray iron and manganese plaques. The soil seasonal gleization occures during the period of soil freezing and thawing, and a positive relationship between the thickness of gleization layer and frozen layer is observed. The process is pseudogley at mild level, with decreasing soil microbial biomass carbon, and increasing cation exchange capacity (CEC), active Fe²⁺, Mn²⁺ and availble phosphuros. The reults suggest that soil gleization may subsequently affect microbial community, root mortality, greenhouse gas emmission and nutrient cycling. Although soil gleization appears in the non-growing season, its impacts on the soil ecological processes should not be ignored.

Based on the warming and altered precipitation experiment platform at Haibei research station, this study investigated the responses of soil inorganic nitrogen to warming and altered precipitation in the growing season in alpine meadow. The results show that 1) warming significantly decreasesNH₄⁺-N by 47.5% (p=0.001) and NO₃-N by 85.4% (p=0.021); 2) effect of decreased precipitation on soil inorganic nitrogen is unequal to the effect of increased precipitation, increased precipitation significantly increasesNH₄⁺-N by 74.7% (p=0.046) and NO₃-N by 154% (p=0.017), while decreases precipitation tends to reduce NH₄⁺-N, but has no significant effect on NO₃-N; 3) NH₄⁺-N and NO₃-N are positively correlated with soil moisture, but has no correlations with soil temperature. Thus, soil moisture induced by warming and altered precipitation, is the main factor affecting inorganic nitrogen availability in the growing season. This study suggests that inorganic nitrogen availability will increase in tandem with increasing soil moisture, under the background of climate change in alpine meadow on the Qinghai-Tibetan Plateau.

An experiment was conducted to investigate the effects of nutrient additions on the arbuscular mycorrhizal fungi (AMF) colonization in the alpine meadow at Haibei field station in China. Treatments of the experiment were control, N addition (10 gN/(m²•a)), P addition (5 gP/(m²•a)), and K addition (10 gK/(m²•a)), each with six replicates. With ink-vinegar staining method, mycorrhizal colonization of roots of the meadow plant community was quantified. Results showed that N addition significantly reduced total mycorrhizal root length colonization by 27%, but had no effect on the arbuscular and vesicular colonization. There was a trend towards reducing AMF colonization by the P addition, but not significantly. K addition did not influence the AMF colonization. The results indicate that there is different influence on the AMF in the alpine meadow with different fertilizer application, which may influence the structure and function of the ecosystem such as the change of species composition. So it is necessary to take the AMF into consideration when evaluating the effects of nutrient additions.

Based on a systematic field sampling and lab measurements of 358 native species, the regional stoichiometric patterns of leaf C, N and Pin Beijing and its periphery were investigated. The geometric means of leaf C, N and P are 45.1% ,2.61% and 0.20 % (dry weight), respectively. The content ratios of lamina C, N and Pto their petiole counterparts are 1.1, 2.4 and 1.8 for C, Nand P, respectively, as reflectsthe stoichiometric relationship between lamina and petiole. Herbs have higher leaf N and P and lower Cthan woody plants; conifers are significantly lower in leaf N( or higher in leaf C) , compared with broadleaves, but there is no significant difference in leaf P between the two growth-forms. Leaf C, N and P are correlated significantly between each other across all species or within growth-forms, with positive relationship between N and P, and negative between C and N ( P). The geometric mean mass ratios of leaf C∶N, C∶P and N∶P are 17.3, 242 and 13.9, respectively.

A field experiment manipulating throughfall was constructed in a Pinus sylvetris var. mongolica plantation at PKU-SOGES. This study investigated the response of two indicators of belowground ecosystem processes, soil microbial biomass carbon and microbial quotient, to±30% throughfall amount. During the growing season from May to September, 2007, soil microbial biomass carbon (260.7 mg/kg) and microbial quotient (1.84 %) decreased with soil depth. Generally, the effects of ±30% throughfall amount on the means of soil microbial biomass carbon and soil microbial quotient in the growing season were not significant. Interestingly, the dynamics were much clear for the -30% throughfall treatment, with soil microbial biomass ranged from 243.1 mg/kg to 354.3 mg/kg and microbial quotient from 1.43% to 2.16%, and the highest value was in May and the lowest was in July. This indicates that the decrease of precipitation in a growing season may lead to a stronger fluctuation in soil microbial activity, thus alter the dynamics of belowground carbon cycle processes.

To determine the change of soil dissolved organic carbon (DOC) following grassland afforestation, the authors compared soil DOC, soil organic carbon (SOC) and soil total N (STN) of top 30cm soils under Leymus chinensis meadow steppe, Pinus sylvestris var. mongolica plantation, and Larix principis-rupprechtii. plantation in Saihanba, Hebei Province. DOC, SOC and STN of coniferous plantation soils were less than those of meadow steppe soils; DOC, SOC, and STN decreased following 40-year grassland afforestation. Soil heterogeneities of coniferous plantations were lower than meadow steppes.