Different management modes can influence land-use and land-cover changes (LULCC), resulting in changes in ecosystem service values (ESV). However, few studies compared the differences in ESV under different management modes. The objective was to analyze the impact of different management modes on ESV. Multisource remote sensing images were used to obtain the LULCC data for Fujin City over four periods (1986, 1995, 2005, and 2015). We modified the equivalent value factors method by crop yield to estimate the ESV in different years. Statistics show that paddy increased from 59.2 to 1341.8 km2 in the agricultural region, whereas it increased from 60.1 to 2236.3 km2 in the reclamation region during 1986 to 2015. The total ESV decreased by 49.0% and 43.4%, respectively, in the agricultural region and reclamation region. The agricultural products function exhibited a larger increase and the freshwater supply function exhibited a greater decrease in the reclamation region than in the agricultural region. Two regions can learn from each other and carry out innovations in land management approaches to promote common developmental goals.
Net radiation (Rn) is the balance between the incoming and outgoing radiation fluxes of longwave and shortwave radiations. As an essential parameter for surface energy budgets, Rn has been widely applied to weather prediction, agriculture evaluation, and regional water resource management. However, the traditional methods for estimating the net radiation are inadequate at the local to regional scales because of their spatial discontinuity and the uneven distribution of radiation sites. With high temporal and spatial resolutions, moderate resolution imaging spectroradiometer data provide numerous terrestrial and atmosphere products, which can help to estimate the shortwave and longwave radiations with limited measured meteorological data. Although many studies have calculated the radiation budget, most of them were applied in North America, where extensive ground validation data are available. In northeastern China, research on the radiation budget was rare, and ground validation data were difficult to acquire, which made our study meaningful and significant. In our work, we have experimented with different parameterization schemes of the components of the radiation budget in our study area and chose the most suitable one to estimate the instantaneous net radiation flux and its components for the study area. The results showed that the RMSE of the downwelling shortwave radiation flux, downwelling longwave radiation flux, upwelling longwave radiation flux, and instantaneous Rn were 31.5, 22.36, 20.61, and 34.32 W/m2, respectively. The sinusoidal model of the diurnal cycle and instantaneous Rn were used to calculate the daily average Rn, and the resulting RMSE was 47.67 W/m2. Finally, the variation of the monthly average Rn of northeastern China in 2011 was analyzed, and the result showed that the temporal and spatial distributions of the monthly average net radiation might be closely related to the land cover types, specifically the seasonal snow cover changes.
The study area including Kerqin Pasture and the farming-pastoral ecotone of Songnen Plain, is located in the
western Northeast China. It is a natural protective screen for the Northeast Plain, which is the most important one of
national food bases, to ensure the food supply security and ecological security. Based on the Landsat5/TM and ETM
remote sensed images of 1986, 1996 and 2000, the grassland dynamic characteristics of the above two parts of the
study area, including change area, transformation, change velocity, are analyzed respectively by land use/land cover
spatial change models. The results show that, the grassland area of Kerqin Pasture decreased by 3,200 km2, while that
of the western Songnen Plain decreased by 4,800 km2. It was mainly due to grassland reclamation activities driven by
rapid population expansion. According to the results of regional differences got by GIS technique, in Kerqin Pasture,
the dynamic degree in Shuangliao county of Jilin province is the largest, up to 2.7%, while the value of Alukerqin
Banner is much smaller, and the grassland is well protected. In the western Songnen Plain, the dynamic degree in
Baicheng and Taonan of Jilin province is more than 4%, primarily caused by grassland reclamation as well. By
contrast, the grassland in Anda city and Qinggang county of Heilongjiang province took a turn for the better with
active protection and improvement measures.