A vegetation configuration pattern with a high-efficiency purification ability for TN, TP, AN, AP, and COD based on comprehensive assessment results.

To identify a vegetation configuration pattern with a high-efficiency purification ability for total nitrogen (TN), available nitrogen (AN), total phosphorous (TP), available phosphorous (AP), and chemical oxygen demand (COD) based on comprehensive assessment results, a water discharge experiment was performed in the Luan River in China with the following riparian forests: I, pure broad-leaved; II, mixed broad-leaved; III, mixed coniferous and broad-leaved; IV, mixed coniferous; and V, pure coniferous. From the riparian buffer zone to the river channel, the evaluation showed that pattern I had the highest purification ability at 1 m and 2 m; at a width of 4 m, pattern III had the highest purification ability; at a distance of 7 m, pattern V showed the highest purification ability; at 10 m, pattern IV showed the highest purification ability, pattern II the lowest. It is advisable to give priority to plant coniferous species from 0 m to 4 m from the river bank, while it is advisable to give priority to plant broad-leaved species from 4 m to 10 m from the river bank. We therefore recommend these vegetation configuration patterns in the development and management of runoff purification systems.

Net anthropogenic phosphorus inputs (NAPI) index application in Mainland China.

This study provides a new understanding on sources of P, which may serve as a foundation for further exploration of anthropogenic effects on P input. Estimation of net anthropogenic phosphorus input (NAPI) was based on an inventory of phosphorus (P) fertilizer use, consumption of human food and animal feed, seeding phosphorus and non-food phosphorus net flux. Across Mainland China, NAPI had an upward trend from 1981 to 2009, which reflects development trend of the population and economic. NAPI for years 1981, 1990, 2000 and 2009 are 190 kg P km(-2)yr(-1) (1.8 kg P per person yr(-1)), 295 kg P km(-2) yr(-1) (2.5 kg P per person yr(-1)), 415 kg P km(-2) yr(-1) (3.1 kg P per person yr(-1)) and 465 kg P km(-2) yr(-1) (3.4 kg P per person yr(-1)), respectively. On a geographical basis, NAPI per unit area is lower in northwest Mainland China than in southeast Mainland China with the largest NAPI of 3101 kg P km(-2) yr(-1) in Shanghai, while NAPI per person is in reverse with the largest NAPI 7.7 kg P per person yr(-1) in Tibet. P input of fertilizer is the largest source of NAPI, accounting for 57.35-83.73% (109-390 kg P km(-2) yr(-1)) of the total NAPI, followed by non-food P and P in human food and animal feed. Year 2000 was a critical point where P changed almost from net input to output. Grain production rate per unit mass of fertilizer showed an obvious downward trend. The primary factor in relation to the change in NAPI is total population.

[Effects of forest vegetation on runoff and sediment production on sloping lands of Loess area].

Based on the 1985 - 2003 fixed-position data in 9 runoff plots of Caijiachuan watershed in the Jixian county of Shanxi Province in loess area, this paper discussed the relationships between vegetation and runoff and sediment production on sloping lands of loess area. The results showed that natural-secondary forest had better function in soil and water conservation than artifical Robinia pseudoacacia forest, with runoff and sediment produced 65% - 82% and 23% - 92%, respectively. Multiple regression analysis indicated that runoff and sediment production had a significant correlation with rainfall and its intensity, but this relationship was decreased gradually with increasing canopy density. Different land-use type had different runoff and sediment production, e. g., Ostryopsis davidiana and natural-secondary forests had the least runoff and sediment production, artificial Robinia pseudoacacia and Pinus tabulaeformis forests had 5 folds of it as much as Ostryopsis davidiana forest, mixed apple trees and crops had 17.14 and 3.96 folds of it than Ostryopsis davidiana forest, respectively, while high-standard soil preparation could decrease the production obviously. Gray correlation analysis suggested that the stand canopy density and the biomass of herb and litter were the most important factors affecting the runoff and sediment production on sloping land, whose gray correlation degrees all exceeded 0.6. Mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction of loess area, which could help to increase the coverage and litter thickness to dramatically decrease the runoff and sediment production on sloping land.

[Nutrient cycling in Castanea mollissima B1 forest at the Miyun reservoir watershed, Beijing].

Studies on the nutrient cycling in Castanea mollissima B1 forest at the Miyun reservoir watershed, Beijing, showed that the total biomass of the Castanea mollissima B1 stands at age 22 was 38,638 kg.hm-2, and the biomass of their stem, branch, leaf, blossom, chestnut, seed capsule and root was 20,160, 8,430, 1429, 873, 1024, 800 and 5,922 kg.hm-2, occupying 52.18%, 21.82%, 3.70%, 2.26%, 2.65%, 2.07%, 15.33% of the total biomass, respectively. The annual average growth amount of stem, branch, and root was 916, 383, and 269 kg.hm-2, respectively, and the total annual average growth amount was 5,694 kg.hm-2. The nutrient contents in different organs of Castanea mollissima B1 stands showed that the N content sequence was leaf > blossom > chestnut > seed capsule > branch > stem, P content sequence was leaf > blossom > branch > stem > seed capsule > chestnut, K content sequence was chestnut > blossom > leaf > chestnut > branch > stem, Ca content sequence leaf > seed capsule > branch > stem > blossom > chestnut, and Mg content sequence was leaf > blossom > branch > chestnut > seed capsule > stem. The storage of N, P, K, Ca and Mg in Castanea mollissima B1 forest was 89.47, 17.34, 74.68, 105.49 and 28.40 kg.hm-2, respectively. The nutrient annual assimilation was 79.17 kg.hm-2, the total annual returning amount 106.55 kg.hm-2, and the annual retention amount was 11.25 kg.hm-2. Among of the total returning, atmospheric dry and wet deposition was 38.36 kg.hm-2, and the litter returning was 58.08 kg.hm-2. The nutrient input was a little more than the output. The storage of the five nutrient elements in 0(-)-30 cm soil layer was 206,427.59 kg.hm-2, and their storage amount in stands only occupied about 0.15% of the total storage in soil. The absorption coefficient of the stands was N > P > K > Ca > Mg, the utilization coefficient was K > N > Mg > P > Ca, and the cycling coefficient was K > N > P > Mg > Ca. The turnover period of the N, P, K, Ca and Mg was 4.34, 7.51, 3.31, 12.90 and 6.45 yr, respectively.