Comparison of N2O Emissions From Cold Waterlogged and Normal Paddy Fields

Paddy fields are major sources of atmospheric N2O. Soil temperature and moisture strongly affect N2O emissions from rice fields. However, N2O emissions from cold-waterlogged paddy fields (CW), an important kind of paddy soil in China, are not well studied so far. It is unclear whether the N2O emissions from cold-waterlogged paddy fields are the same as normal paddy fields (NW). We investigated the N2O emission characteristics from the CW and NW paddy fields under with (R1) and without (R0) rice in Tuku Village, Baisha Town, Yangxin County (YX site, monitoring in 2013) and Huandiqiao Town, Daye City (DY site, monitoring in 2014); compared the difference and influencing factors between the CW and NW paddy fields at two sites in South China. The results showed that the N2O emissions from NWR0 were 13.4 times higher than from CWR0, and from NWR1 were 10.3 times higher than from CWR1 in the YX site. The N2O emissions from NWR0 were 2.4 times higher than from CWR0, and from NWR1 were 17.3 times higher than from CWR1 in the DY site. The structural equation models (SEMs) showed that the N2O emissions are mainly driven by rice planting and soil moisture in the NW fields at the annual scale, while soil temperature in the CW fields. Overall, N2O emissions from cold waterlogged paddy fields are significantly lower than those of normal paddy fields due to the low temperature and higher water content; however, there are dinitrogen emissions from cold waterlogged paddy fields denitrification should be further examined.

Land-Use Conflict Identification from the Perspective of Construction Space Expansion: An Evaluation Method Based on ‘Likelihood-Exposure-Consequence’

Land-use conflict (LUC) is a major problem of land management in the context of rapid urbanization. Conflict identification plays an important role in the development and protection of land space. Considering the possibility of, exposure to, and negative impacts of LUC, we explore the probability of land-use cover change (LUCC), policy constraints, and ecosystem service value (ESV) and build a conflict identification model based on the LEC concept of risk assessment. Taking Daye City as an example, we classify the conflict intensity and delimit the key conflict areas. At the same time, a composite classification system is constructed to analyze the spatial characteristics and internal mechanism of conflict. We find that the conflict between construction and ecological space is the main conflict in Daye City (P.R. China), which is widely distributed. However, the conflict between construction and agricultural space, which is mainly distributed near the center of Daye City, cannot be ignored.

ECO-ENVIRONMENTAL ASSESSMENT AND ANALYSIS OF TONGLVSHAN MINING AREA IN DAYE CITY, HUBEI PROVINCE BASED ON SPATIOTEMPORAL METHODOLOGY

Mine exploitation has a significant impact on the ecological environment status of the surroundings. To analyze the impact of Tonglvshan Mining area to its surroundings, this paper adopted the spatiotemporal methodology based on the extracted Eco-environmental Quality Index (EQI) to analysis the extent and degree of the effect. The spatiotemporal methodologies are based on two scales: buffers and administrative units. EQI includes Biological Abundance Index (BAI), Vegetation Index (VI), Water Network Density Index (WNDI), and Land Degradation Index (LDI). The weight of each Index was determined by the analytic hierarchy process (AHP) and scores of the experts. The calculating of EQI was referenced to the standard “Technical criterion for Eco-environment Status Evaluation” （HJ/T192-2006）and the “Standards for Classification and Gradation of Soil Erosion” （SL 190-96）. Considering ecological and environmental characteristics relevant to China, this method has been widely used to study the environment status of specific regions in China. The assessment based on buffers adopted the radius of 300m, 500m, 700m, 1000m, 1500m, 2000m, 2500m, 3000m, 3500m, and 4000m as the buffers in 3 typical miners respectively. The calculated result indicates that, the REI is increasing with the radius and the increasing rate becoming smaller until REI is stable. Which means the effect of miner is getting weaker with the distance to the miner is increasing and the effect is diminished when the distance is far enough. The analysis of the 3 typical miner shows that the extent and degree of the effect of miner relates not only with the area of the miner, but also with type of mineral resource, the status of mining and the ecological restoration. The assessment was also carried out by calculating the EQI in 14 administrative units in Daye city in 2000, 2005, and 2010. The study shows that the EQI is decreasing in 14 units from 2000 to 2010. The spatiotemporal analysis of the type and area of land cover in 14 units within ten years period ranging from 2000 to 2010 shows that the mainly factor to affect the eco-environment status is mine exploitation and urban expansion.