Cleaner agricultural production in drinking-water source areas for the control of non-point source pollution in China.

With continuous population growth and acceleration of urbanization in China, environmental problems in drinking-water source areas have become increasingly prominent. In some places, domestic wastewater and aquaculture sewage are directly discharged into water bodies without any treatment. Also, large amounts of domestic garbage and aquaculture waste are often randomly stacked, seriously polluting the surrounding groundwater and surface water and deteriorating the water quality. Notably, some agricultural production activities can also cause non-point source pollution, resulting from eutrophication of water bodies. In some instances, these activities can lead to nitrogen losses of 0.7%-83.9% and phosphorus losses of 0.6%-82.8%. In view of this situation, the implementation of cleaner agricultural production is of great significance for protecting the environment in drinking-water source areas and maintaining drinking-water safety. Specific practicable measures include formula fertilization through soil testing, integrated pest management, and water-saving irrigation technology. For the livestock- and poultry-breeding industry, it is necessary for large-scale farms to construct excreta discharge treatment facilities, carry out harmless treatment and resource utilization of organic wastes, establish rural biogas septic tanks, and make use of domestic-sewage and livestock-breeding wastewaters. Also, fixed garbage-dumping sites should be built in rural water-source areas, and a unified garbage-disposal station set up to reduce the pollution discharge of domestic garbage. Moreover, it is crucial to strictly control the development and utilization of hillsides in the middle and upper reaches of the drinking-water source area, as well as strengthen the restoration of vegetation and the construction of soil and water conservation forests in these areas.

Influences of micro-geomorphology on the stoichiometry of C, N and P in Chenier Island soils and plants in the Yellow River Delta, China.

Studies have indicated that consistent or well-constrained (relatively low variability) carbon:nitrogen:phosphorus (C:N:P) ratios exist in large-scale ecosystems, including both marine and terrestrial ecosystems. Little is known about the C, N and P stoichiometric ratios that exist in the soils and plants of Chenier Island in the Yellow River Delta (YRD). We examined the distribution patterns and relationships of C, N and P stoichiometry in the soils and plants of Chenier Island, as well as the potential influences of the island's micro-geomorphology. Based on a study of four soil profile categories and Phragmites australis and Suaeda heteroptera plant tissues, our results showed that micro-geomorphology could leave a distinct imprint on the soil and plant elemental stoichiometry of Chenier Island; significant variation in the atomic C:N:P ratios (RCNP) existed in soils and plants, indicating that the RCNP values in both the soil and plants are not well constrained at the Chenier Island scale. RCN and RCP in Chenier Island soils were high, whereas the RNP values were comparatively low, indicating that the ecosystems of Chenier Island are nutrient-limited by N and P. However, the RNP values in P. australis and S. heteroptera plant tissues were high, suggesting that the plants of Chenier Island are nutrient-limited by P. Finally, we suggest that soil and plant N:P ratios may be good indicators of the soil and plant nutrient status during soil development and plant growth, which could be a useful reference for restoring the degraded soils of Chenier Island.

[Dynamics of forest community structure and complexity in the process of secondary succession in bedrock area of west Shanxi Province].

In this paper, four plots representing the typical secondary succession stages of forest community were selected at the shady slope of bedrock area in Zhongyang County of West Shanxi, aimed to study the variation patterns of the structure and complexity of forest community in the process of secondary succession. The results showed that in the succession process of the community, there was an evident regularity in the variation of height and diameter class structure. The proportion of high and big individuals in the community increased gradually, while that of low and small ones increased first but decreased then. From the viewpoint of height class structure, the compositional complexity of tree species H (X), structural complexity of tree species H (Y/X), and complexity of whole community H (X,Y) all increased first, but decreased then with the succession. At the early, middle and arbor stages of succession, the H(X) value was 2.96, 3.85 and 3.75, while H (Y/X) value was 1.27, 1.66 and 1.37, respectively.

[Quantitative classification and ordination of subalpine meadow in Wolong Nature Reserve].

Based on the field investigation of 114 sampling plots at Balong Mountain in Wolong Nature Reserve, this paper studied the plant species composition and community structure of subalpine meadow communities. Two-way indicator species analysis and detrended correspondence analysis were employed to classify and ordinate the subalpine meadow communities in these sampling plots, aimed to understand the key factors determining the structure and distribution pattern of subalpine meadow communities. Through TWINSPAN analysis, the subalpine meadow was classified into 12 types. DCA ordination gave the ecological significance of ordination axes. Axis 1 indicated the altitude the meadow distributed, while axis 2 indicated the soil humidity of the distribution site. The ordination of dominant species was similar to the classification of community types, reflecting the change trend of community type and species distribution with changing environmental factors.