[Spatio-temporal Variation of PM2.5 Related Relationships in China from the Perspective of Air Pollution Regional Linkage Control and Prevention].

Identification of spatio-temporal variation of PM2.5 related relationships under joint management zones is of great significance for scientifically conducting joint control of air pollution in China. Based on the PM2.5 concentration data of 334 prefecture-level cities in China from 2000 to 2016, from the perspective of air pollution regional linkage control and prevention, this paper systematically analyzes the spatio-temporal variation of PM2.5 related relationships in China using a spatial unit aggregation strategy and geographically and temporally weighted regression. The results show that:① With PM2.5 as the primary pollutant, ten air pollution joint management areas are obtained by considering the degree of pollution, geographical location, meteorology, topography, and economy. ② Geographically and temporally weighted regression can effectively reveal the spatio-temporal non-stationarity of the relationships between PM2.5 concentration and related factors. Meanwhile, population size, secondary industry gross domestic product, SO2 emissions, annual average temperature, annual precipitation, and annual relative humidity are identified as having a significant effect on changes in PM2.5 concentration. ③ The population impacts on PM2.5 concentration in the Beijing-Tianjin-Yunmeng region are the largest of all regions during the period. The influence of the secondary industry's gross domestic product on the PM2.5 concentration in the Sichuan-Yunnan District is the most variable. Apart from these values in the northeast of China, the regression coefficient values of SO2 emissions first decrease with time, then increase, and then decrease again. The time variability of the average annual temperature of each treatment area to PM2.5 is small. The influences of annual precipitation and annual average relative humidity on PM2.5 present different variability characteristics in each region.

[Spatial distribution of aboveground biomass of shrubs in Tianlaochi catchment of the Qilian Mountains].

This study estimated the spatial distribution of the aboveground biomass of shrubs in the Tianlaochi catchment of Qilian Mountains based on the field survey and remote sensing data. A relationship model of the aboveground biomass and its feasibly measured factors (i. e. , canopy perimeter and plant height) was built. The land use was classified by object-oriented technique with the high resolution image (GeoEye-1) of the study area, and the distribution of shrub coverage was extracted. Then the total aboveground biomass of shrubs in the study area was estimated by the relationship model with the distribution of shrub coverage. The results showed that the aboveground biomass of shrubs in the study area was 1.8 x 10(3) t and the aboveground biomass per unit area was 1598.45 kg x m(-2). The distribution of shrubs mainly was at altitudes of 3000-3700 m, and the aboveground biomass of shrubs on the sunny slope (1.15 x 10(3) t) was higher than that on the shady slope (0.65 x 10(3) t).

[Water storage capacity of qinghai spruce (Picea crassifolia) forest canopy in Qilian Mountains].

By the methods of direct measurement and regression analysis, this paper estimated the water storage capacity of Picea crassifolia forest canopy in Guantan in Qilianshan Mountains, based on the observed throughfall and the laboratory experimental data about the water storage capacity of various canopy components in 2008. Due to the impacts of various factors, differences existed in the canopy water storage capacity estimated by the two methods. The regression analysis was mainly impacted by the measurement approaches of the throughfall, the maximum water storage capacity estimated being 0.69 mm, whereas the direct measurement was mainly impacted by tree height, diameter at breast height, plant density, and leaf area index, with the estimated maximum water storage capacity being 0.77 mm. The direct measurement showed that the maximum water storage capacity per unit area of the canopy components of the forest was in the order of barks (0.31 mm) > branches (0.28 mm) > leaves (0.08 mm).

[Spatial distribution of Tamarix ramosissima aboveground biomass and water consumption in the lower reaches of Heihe River, Northwest China].

Based on the field observation on the Tamarix ramosissima populations in the lower reaches of Heihe River, the relationship models between the aboveground biomass of T. ramosissima and its morphological features (basal diameter, height, and canopy perimeter) were built. In the mean time, the land use/cover of the study area was classified by the decision tree classification with high resolution image (QuickBird), the distribution of T. ramosissima was extracted from classification map, and the morphological feature (canopy perimeter) of T. ramosissima was calculated with ArcGIS 9.2. On the bases of these, the spatial distribution of T. ramosissima aboveground biomass in the study area was estimated. Finally, the spatial distribution of the water consumption of T. ramosissima in the study area was calculated by the transpiration coefficient (300) and the aboveground biomass. The results showed that the aboveground biomass of T. ramosissima was 69644.7 t, and the biomass per unit area was 0.78 kg x m(-2). Spatially, the habitats along the banks of Heihe River were suitable for T. ramosissima, and thus, this tree species had a high biomass. The total amount of water consumption of T. ramosissima in the study area was 2.1 x 10(7) m3, and the annual mean water consumption of T. ramosissima ranged from 30 mm to 386 mm.