[Environmental impact differences in Qingtian rice-fish culture system at different management scales in the context of land transfer: An empirical study with the carbon footprint method.] / åœŸåœ°æµè½¬èƒŒæ™¯ä¸‹ä¸åŒç»è¥è§„æ¨¡é’ç”°ç¨»é±¼å ±ç”Ÿç³»ç»Ÿçš„çŽ¯å¢ƒå½±å“å·®å¼‚­­åŸºäºŽç¢³è¶³è¿¹çš„å®žè¯ç ”ç©¶.

Under rapid industrialization and urbanization, the conservation and management of agricultural heritage systems is facing many threats and challenges, such as the massive outflow of working labor, land abandonment, and the difficulty in maintaining traditional knowledge systems. Promoting land transfer and carrying out moderate-scale management play an active role in the conservation of agricultural heritage systems. While land transfer brings economic benefits to heritage sites, its environmental impacts to heritage sites are worthy of attention. However, empirical studies are scarce. This study took Qingtian rice-fish culture system in Zhejiang Province as an example, which was designated as Globally Important Agricultural Heritage Systems (GIAHS) in 2005. Small farmer management model and land scale management model were distinguished, while the life cycle method was used to calculate the carbon footprints of two models. The results showed that the carbon footprints of small farmer management model and land scale management model were 6510.80 and 5917.00 kg CO2-eq·hm-2, respectively, while the carbon footprints per unit output were 0.13 and 0.10 kg CO2-eq·yuan-1, respectively. Compared with small farmer management model, land scale management model had lower greenhouse gas emission and lower environmental impact of per unit output. As farmers expanded the scale of land management, local greenhouse gas emissions had been reduced by 4097.20 kg CO2-eq. Furthermore, the accumulation of CH4 in agricultural production accounted for the largest proportion of carbon footprint. The input of compound fertilizer among agricultural production materials was next to CH4 accumulation, becoming the second largest source of greenhouse gas emission. Corn and wheat being used as fish feed also had a significant impact on greenhouse gas emission in small farmer management model. Therefore, the promotion of moderate scale land management is conducive to the win-win of economic and environmental benefits of traditional agricultural systems and plays an important role in the conservation of agricultural heritage systems.

[Measuring water ecological carrying capacity with the ecosystem-service-based ecological footprint (ESEF) method: Theory, models and application].

Integrated watershed management based on aquatic ecosystems has been increasingly acknowledged. Such a change in the philosophy of water environment management requires recognizing the carrying capacity of aquatic ecosystems for human society from a more general perspective. The concept of the water ecological carrying capacity is therefore put forward, which considers both water resources and water environment, connects socio-economic development to aquatic ecosystems and provides strong support for integrated watershed management. In this paper, the authors proposed an ESEF-based measure of water ecological carrying capacity and constructed ESEF-based models of water ecological footprint and capacity, aiming to evaluate water ecological carrying capacity with footprint methods. A regional model of Taihu Lake Basin was constructed and applied to evaluate the water ecological carrying capacity in Changzhou City which located in the upper reaches of the basin. Results showed that human demand for water ecosystem services in this city had exceeded the supply capacity of local aquatic ecosystems and the significant gap between demand and supply had jeopardized the sustainability of local aquatic ecosystems. Considering aqua-product provision, water supply and pollutant absorption in an integrated way, the scale of population and economy aquatic ecosystems in Changzhou could bear only 54% of the current status.

[Effects of different rice farming systems on paddy field weed community].

Taking the paddy fields planted with glutinous rice and hybrid rice in the traditional agricultural region in Congjiang County of Guizhou Province as the case, and by using semi-experiment combined with random sampling investigation, this paper studied the characteristics of weed community in the paddy fields under rice monoculture (R), rice-fish culture (R-F), and rice-fish-duck culture (R-F-D). Under the three rice farming systems, glutinous rice had higher capability in inhibiting weeds, compared with hybrid rice. Farming system R-F-D decreased the weed density significantly, with the control effect on Monochoia vaginalis and Rotala indica being 100%. The overall weed-inhibiting effect of R-F-D was significantly higher than that of the other farming systems. Under R-F-D, the species richness and Shannon diversity index of weed community decreased markedly, while the Pielou evenness index increased, indicating that the species composition of weed community changed greatly, and the occurrence of native dominant weed species decreased. It was concluded that R-F-D was a feasible farming system for the control of paddy field weed community.

[Experimental research on the anti-wind erosion of typical grasslands].

Wind erosion is one of the most important factors influencing the stability and functions of typical grassland ecosystem and one of the main reasons causing grassland degradation. In order to understand the effects of the human disturbances to the ability of anti-wind erosion of the typical grasslands, a wind tunnel experiment was made and the wind erosion rates (WER) and wind erosion amount (WEA) were selected to illustrate the effects. From the experiment, it can be found that banned-grazing reduced the WEA and the WER markedly. At the same wind speed, the longer the banned-grazing period, the less the WEA and the WER; the WEA and the WER in the grassland cultivation are more than those of the natural grasslands and the differences increase with wind speed. There exists a linear relationship between WER and the disturbance intensity. The results show that grazing and cultivation can weaken the ability of anti-wind erosion of typical grassland ecosystem, and banned-grazing can strengthen the ability. Therefore, in typical grassland areas, taking the active banned-grazing measures is the most effective approach to stop the degradation and trigger the rehabilitation of typical grassland ecosystem.

[Ecological water requirement of forests in Loess Plateau].

Converting degraded farmlands to forest or grass lands is the best approach to reduce the soil erosion, the Loess Plateau is faced with most serious ecological disaster. Loess Plateau located in the arid and semi-arid regions is a fragile region with the characteristics of little precipitation and intensive evapotranspiration. Therefore, water is the most important factor limiting the eco-restoration and construction of the vegetation in the region. According to the latest digital land use map and with GIS, the ecological water requirement for forests in Loess Plateau was estimated, and by the water balance of the forest ecosystem in their growing season, the ecological water shortage was calculated. The results revealed that the minimum and suitable ecological water requirement of the forests in Loess Plateau were approximately 262.49 x 10(8) m3 and 421.34 x 10(8) m3 respectively. Accordingly, if it is taken the minimum ecological water requirement as the quota, the area of forests suffered water shortage was about 7,639.09 km2, 9.1% of all, and the ecological water shortage was amounted to 4.77 x 10(8) m3; if it is taken the suitable ecological water requirement as the quota, the forest land area suffered water shortage was about 57.7% of all, and the ecological water shortage was roughly 58.55 x 10(8) m3.