Search

The porosity and effective permeability values of an oil layer in different periods of the same block are quite different, It is proposed to take the actual production target interval and small block in block A as the unit, by analyzing the results of laboratory water flooding experiments and using the data of coring wells and exploration wells in the study area, as well as the data of static database, the variation rules of porosity and effective permeability in different development stages are summarized. After comprehensive study, it is found that the change of parameter interpretation model and water injection development are the main factors for the change of hole and permeability parameters of well completion logging interpretation in different periods in block A.

Evaluation of influences of the Beijing–Tianjin Sand Source Control Project on soil wind erosion and ecosystem services is imperative for mastering the benefits and drawbacks of the program, as well as for distinguishing more reasonable estimations to evaluate regional sustainable development. Within the Beijing–Tianjin Sand Source Region, we quantified the spatiotemporal patterns of land use/cover changes (LUCCs), soil wind erosion modulus (SWEM), and essential ecosystem services throughout 2000–2015 by utilizing field investigations, remotely sensed data, meteorological data, and modeling. The influences of ecological projects on wind erosion and ecosystem services has been subsequently assessed by using those modifications brought on via the LUCCs (e.g., conversion from cropland to grassland/woodland) during the ecological construction. The results indicated that the SWEM showed a decline and ecosystem services which included carbon storage, water retention, and air quality regulation exhibited growth driven by using both local climate exchanges and human activities such as ecological projects. Excluding the effects of climate factors, the LUCCs stemming from ecological projects caused a total SWEM decrease of 3.77 million tons during 2000–2015, of which approximately 70% was prompted by the way of the transition from desert to sparse grassland. And from this transition, ecosystem services including both water retention and aboveground net primary productivity manifest a general increase. The sub-regions of desert grassland in Bayannur, Ordos Sandy Land, and Otindag Sandy Land were hot spots for wind erosion declines and ecosystem service enhancements induced by the ecological projects. We recommend that endeavors be coordinated toward the scientific management of the degraded lands and distribution of the local populace, as well as the implementation of diverse measures in the expected hotter and drier future.

To identify the effects of shelterbelt establishment on soil recovery, we compared soil properties at depths of 0–5, 5–10, and 10–20 cm as affected by Caragana korshinskii shelterbelts across a chronosequence of soil undergoing restoration for 7, 11, and 26 years, as well as reference grasslands in Ningxia, NW China. Fractal dimension of soil particle size distribution (PSD) was also integrated to describe variations in soil properties. The results indicated that (1) fine particles, total porosity, total nitrogen, phosphorous, and available nitrogen, phosphorous, and potassium increased significantly with plantation age (p

China is the global leader in afforestation efforts to restore degraded forest ecosystems. However, it is diffi cult for these efforts to completely substitute for natural forests. In order to reveal the differences between plantations and natural forests, we compared stand spatial structure of plantations, mixed plantations, and natural forests by using the mingling degree (M i ), uniform angle index (W i ), and neighborhood comparison ( U i ) in the Mulan-Weichang Forestry Administrative region of the rocky mountain area, northern China. The results indicated that natural forests were characterized by varying species composition, individual tree distribution, and competitive relationships, which were more complex than monoculture plantations. Forest management is benefi cial to stand spatial structure improvement, resulting in mixed plantations that are closer to natural forests. On this basis, China’s forest policy should shift focus from afforestation for area expansion to forest management for ecological improvement.

This study was conducted in Ningxia Hui autonomous region, located at southern part of Mu Us sand land in China. To investigate relationships between windbreak effect and installation cost of sand barriers, plastic net is utilized by using four kind of heights (0.2, 0.3, 0.4 and 0.5m) and four kind of porosities (20, 30, 50 and 70%). These heights and porosities are measured for estimating distances for effective windbreak. It is shown that porosity and the distance have a positive relationship at same heights and porosity on ground indicates a constant figure when height reaches a certain level, regardless of the porosity. This implies that there is a difference of level of windbreak with different porosities; however, distance of windbreak effect is same at the same height of sand barrier. As a result of comparison between porosity of sand barrier on the ground and installation cost in each sand barrier with various heights and porosities (16 combinations), 0.4m and 0.5m height sand barriers describe highest economical efficiency. Within two variables, we concluded that height has a higher impact on windbreak effect than porosity.

Structure-based forest management is a scientific and easy-to-operate method for sustainable forest management. We analyzed the stand spatial structure of Larix principis-rupprechtii plantation under five reserve densities. The results indicated that with the decrease of densities after thinning, the average mingling degree and uniform angle index had an increasing tendency, but the amplitude was small. Most of the trees were in zero mix, and a few of them were in moderate, strong, and relatively strong mix; the horizontal distribution patterns were uniform or near-uniform random. The distribution of neighborhood comparison and opening degree changed with a fluctuant pattern, but thinning decreased the competitive intensities to some extent. A composite structure index (Ci) was established, based on the relative importance of the above four indicators, to evaluate the overall effect of thinning on stand structure characteristics. The findings showed that Ci increased with the increase of thinning intensity, that is, the stand spatial structure became more complex. This indicated that Ci may be a simple and rapid indicator to evaluate the overall effect of thinning on stand spatial structure within densities after thinning.

BackgroundBiological soil crusts are common components of desert ecosystem; they cover ground surface and interact with topsoil that contribute to desertification control and degraded land restoration in arid and semiarid regions.Methodology/principal findingsTo distinguish the changes in topsoil affected by biological soil crusts, we compared topsoil properties across three types of successional biological soil crusts (algae, lichens, and mosses crust), as well as the referenced sandland in the Mu Us Desert, Northern China. Relationships between fractal dimensions of soil particle size distribution and selected soil properties were discussed as well. The results indicated that biological soil crusts had significant positive effects on soil physical structure (PConclusions/significanceBiological soil crusts cause an important increase in soil fertility, and are beneficial to sand fixation, although the process is rather slow. Fractal dimension proves to be a sensitive and useful index for quantifying changes in soil properties that additionally implies desertification. This study will be essential to provide a firm basis for future policy-making on optimal solutions regarding desertification control and assessment, as well as degraded ecosystem restoration in arid and semiarid regions.

Aim of study: Forests have vital functions in global carbon cycle, and thus are of prime importance in efforts to curb climate change. This study intends to guide effective forestry solutions to combat climate change in China.Area of study: China, not only a major emitter of greenhouse gases, but also one of the five most-forest richest countries with the largest plantations in the world.Material and methods: We summarize and recommend carbon sequestration forestry by considering two Kyoto Protocol activities: afforestation/reforestation and forest management.Main results: Afforestation has a top priority of carbon sequestration forestry in China. However, the tree-based solution will reach its limits to growth in a predictable near future. Forest management contributes to break the deadlock. When scientifically and sustainably managed, forests still have a central role in climate change mitigation. Research highlights: China’s efforts on carbon sequestration forestry should shift the focus from afforestation to forest management.Key words: climate change; carbon sequestration forestry; afforestation; forest management.

We constructed an aeolian soil database across arid, semi-arid, and dry sub-humid regions, China. Soil particle size distribution was measured with a laser diffraction technique, and fractal dimensions were calculated. The results showed that: (i) the predominant soil particle size distributed in fine and medium sand classifications, and fractal dimensions covered a wide range from 2.0810 to 2.6351; (ii) through logarithmic transformations, fractal dimensions were significantly positive correlated with clay and silt contents (R2 = 0.81 and 0.59, P < 0.01), and significantly negative correlated with sand content (R2 = 0.50, P < 0.01); (3) hierarchical cluster analysis divided the plots into three types which were similar to sand dune types indicating desertification degree. In a large spatial scale, fractal dimensions are still sensitive to wind-induced desertification. Therefore, we highly recommend that fractal dimension be used as a reliable and quantitative parameter to monitor soil environment changes in desertified regions. This improved information provides a firm basis for better understanding of desertification processes.