Zone Of Northern China Research Articles

Spatio-Temporal Variations of Rain-Use Efficiency in the West of Songliao Plain, China

Spatio-temporal patterns of rain-use efficiency (RUE) can explicitly present the steady-state of ecosystem water use and thus ecosystem functioning. The west of Songliao Plain, located along the east fringe of the agro-pasture transitional zone in northern China, is highly sensitive to global change. In this study, satellite-based RUE was calculated using time series SPOT VEGETATION (SPOT-VGT) Normalized Difference Vegetation Index (NDVI) images and precipitation data for the study area from 1999 to 2011. Based on regression model by fitting simple linear regression through the pixel-based time series of RUE in the growing season and calculating the slopes, the change trend of RUE was determined. The grey relational analysis (GRA) method was extended to the spatial scale, and used to select sensitive climate and socio-economic factors that affected RUE variations. The result demonstrated that vegetation RUE increased slightly with an undulating trend, implying the ecosystem function tended to improve between 1999 and 2011. In total, 4.23% of the total area had experienced a significant increase in RUE, whereas 1.29% of the total area presented a significant decrease. Areas showing increased RUE trends mostly coincided with areas of land cover conversions from grassland to forest, shrub to forest and cropland to forest, which suggested a positive linkage with ecological protection policy and projects at national and local levels. Based on the obtained spatial Grey Relation Grade (GRG) values, the pattern of the impact factors clearly showed a spatial heterogeneity. Spatially, sunshine duration, temperature and population density were most closely related to RUE in the west of Songliao Plain between 1999 and 2011.

Environmental Controls Over Actinobacteria Communities in Ecological Sensitive Yanshan Mountains Zone.

The Yanshan Mountains are one of the oldest mountain ranges in the world. They are located in an ecologically sensitive zone in northern China near the Hu Huanyong Line. In this metagenomic study, we investigated the diversity of Actinobacteria in soils at 10 sites (YS1–YS10) on the Yanshan Mountains. First, we assessed the effect of different soil prtreatment on Actinobacteria recovery. With the soil pretreatment method: air drying of the soil sample, followed by exposure to 120°C for 1 h, we observed the higher Actinobacteria diversity in a relatively small number of clone libraries. No significant differences were observed in the Actinobacterial diversity of soils from sites YS2, YS3, YS4, YS6, YS8, YS9, or YS10 (P > 0.1). However, there were differences (P < 0.05) from the YS7 site and other sites, especially in response to environmental change. And we observed highly significant differences (P < 0.001) in Actinobacterial diversity of the soil from YS7 and that from YS4 and YS8 sites. The climatic characteristics of mean active accumulated temperature, annual mean precipitation, and annual mean temperature, and biogeochemical data of total phosphorus contributed to the diversity of Actinobacterial communities in soils at YS1, YS3, YS4, and YS5 sites. Compared to the climatic factors, the biogeochemical factors mostly contributed in shaping the Actinobacterial community. This work provides evidence that the diversity of Actinobacterial communities in soils from the Yashan Mountains show regional biogeographic patterns and that community membership change along the north-south distribution of the Hu Huanyong Line.

Environmental Change in the Agro-Pastoral Transitional Zone, Northern China: Patterns, Drivers, and Implications.

Chengde city is located in the agro–pastoral transitional zone in northern China near the capital city of Beijing, which has experienced large-scale ecological construction in the past three decades. This study quantitatively assessed the environmental changes in Chengde through observation records of water resources, water environment, atmospheric environment, and vegetation activity and investigated the possible causes. From the late 1950s to 2002, the streamflow presented a downward trend induced by climate variability and human activities, with contribution ratios of 33.2% and 66.8%, respectively. During 2001–2012, the days of levels I and II air quality presented clear upward trends. Moreover, the air pollutant concentration was relatively low compared with that in the adjacent areas, which means the air quality has improved more than that in the neighboring areas. The water quality, which deteriorated during 1993–2000, began to improve in 2002. The air and water quality changes were closely related to pollutant emissions induced by anthropogenic activities. During 1982–2012, the vegetation in the southeastern and central regions presented restoration trends, whereas that in the northwestern area showed degradation trends. The pixels with obvious degradation trends correlated significantly with annual mean temperature and annual precipitation. Ecological engineering also played a positive role in vegetation restoration. This analysis can be beneficial to environment managers in the active response and adaptation to the possible effects of future climate change, population growth, and industrial development and can be used to ensure sustainable development and environmental safety.

The effect of past climatic oscillations on spatial genetic structure of Atraphaxis manshurica (Polygonoideae) in the Horqin sandlands, northern China

To investigate the effect of past climate oscillations on the genetic diversity and demographic history of organisms in the Horqin sandlands, at the margin of the monsoonal zone in northern China. We selected Atraphaxis manshurica as a model and examined the spatial genetic structure in populations of this species across most of its covered range. Five haplotypes were identified on the basis of two chloroplast DNA sequences (psbK-psbI and psbB-psbH) in 127 individuals from 11 natural populations. The total genetic diversity (HT = 0.437) of A. manshurica is low compared with species to the west in arid northwestern China, outside of monsoonal influence. Analysis of molecular variance (AMOVA) indicates that genetic differentiation primarily occurred among two geographical groups distinguished by spatial analysis of molecular variance (SAMOVA). The BEAST molecular clock approach revealed that genetic divergence of the species mostly occurred in middle-late Pleistocene, in accordance with the periodic glacial periods and accompanying monsoonal changes. From species distribution modeling (SDM), we found that the species experienced range contraction and southward retreat during the Last Glacial Maximum (LGM). The current genetic pattern and demographic history may have thus been shaped by glacial–interglacial cycles and changes of habitat since the middle Pleistocene.

Response of vegetation and soil carbon and nitrogen storage to grazing intensity in semi-arid grasslands in the agro-pastoral zone of northern china.

Overgrazing has been the primary cause of grassland degradation in the semi-arid grasslands of the agro-pastoral transition zone in northern China. However, there has been little evidence regarding grazing intensity impacts on vegetation change and soil C and N dynamics in this region. This paper reports the effects of four grazing intensities namely un-grazed (UG), lightly grazed (LG), moderately grazed (MG) and heavily grazed (HG) on vegetation characteristics and soil properties of grasslands in the Guyuan county in the agro-pastoral transition region, Hebei province, northern China. Our study showed that the vegetation height, canopy cover, plant species abundance and aboveground biomass decreased significantly with increased grazing intensity. Similarly, soil organic carbon (SOC) and total nitrogen (STN) in the 0–50 cm were highest under UG (13.3 kg C m−2 and 1.69 kg N m−2) and lowest under HG (9.8 kg C m−2 and 1.22 kg N m−2). Soil available nitrogen (SAN) was significantly lower under HG (644 kg N hm−2) than under other treatments (725–731 kg N hm−2) in the 0–50 cm. Our results indicate that the pasture management of “take half-leave half” has potential benefits for primary production and livestock grazing in this region. However, grazing exclusion was perhaps the most effective choice for restoring degraded grasslands in this region. Therefore, flexible rangeland management should be adopted in this region.

Impacts of land use and land cover changes on biogenic emissions of volatile organic compounds in China from the late 1980s to the mid-2000s: implications for tropospheric ozone and secondary organic aerosol

Based on the MEGAN (Model of Emissions of Gases and Aerosols from Nature) module embedded within the global chemical transport model (GEOS-Chem), we estimate the changes in emissions of biogenic volatile organic compounds (BVOCs) and their impacts on surface-layer O3 and secondary organic aerosols (SOA) in China between the late 1980s and the mid-2000s by using the land cover dataset derived from remote sensing images and land use survey. The land cover change in China from the late 1980s to the mid-2000s can be characterised by an expansion of urban areas (the total urban area in the mid-2000s was four times that in the late 1980s) and a reduction in total vegetation coverage by 4%. Regionally, the fractions of land covered by forests exhibited increases in southeastern and northeastern China by 10–30 and 5–15%, respectively, those covered by cropland decreased in most regions except that the farming–pastoral zone in northern China increased by 5–20%, and the factions of grassland in northern China showed a large reduction of 5–30%. With changes in both land cover and meteorological fields, annual BVOC emission in China is estimated to increase by 11.4% in the mid-2000s relative to the late 1980s. With anthropogenic emissions of O3 precursors, aerosol precursors and aerosols fixed at year 2005 levels, the changes in land cover and meteorological parameters from the late 1980s to the mid-2000s are simulated to change the seasonal mean surface-layer O3 concentrations by −4 to +6 ppbv (−10 to +20%) and to change the seasonal mean surface-layer SOA concentrations by −0.4 to +0.6 µg m−3 (−20 to +30%) over China. We find that the decadal changes in meteorological parameters had larger collective effects on BVOC emissions and surface-layer concentrations of O3 and SOA than those in land cover and land use alone. We also perform a sensitivity simulation to compare the impacts of changes in anthropogenic emissions on concentrations of O3 and SOA with those of the changes in meteorological parameters and land cover.

Asymmetric effects of soil moisture on mean daily maximum and minimum temperatures over eastern China

This study statistically investigates the effects of soil moisture on mean daily maximum ( $$T_{\rm{max} }$$ ) and minimum temperatures ( $$T_{\rm{min} }$$ ) over eastern China in spring (from March to May), summer (from June to August) and fall (from September to November), using the Global Land Data Assimilation System (GLDAS) soil moisture and observational temperatures. The results show that soil moisture exerts asymmetric effects on $$T_{\rm{max} }$$ and $$T_{\rm{min} }$$ , thereby has substantial effects on the diurnal temperature range (DTR) in the three seasons. The soil moisture feedbacks on $$T_{\rm{max} }$$ , $$T_{\rm{min} }$$ , and DTR are found to evidently vary with season. In spring and summer, soil moisture exerts stronger negative forcing on $$T_{\rm{max} }$$ than $$T_{\rm{min} }$$ , and thus has negative effects on the DTR over many areas of northern China. In fall, soil moisture has much stronger positive effects on $$T_{\rm{min} }$$ than $$T_{\rm{max} }$$ , and thus has significant negative effects on the DTR over Northeast China and some areas of the climatic and ecological transition zone of northern China. The uncertainties in the employed data and method should be noted. Therefore, the results need to be further investigated by other data sets and methods in the future.

Preliminary study on the stalagmite &amp;lt;italic&amp;gt;&amp;delta;&amp;lt;/italic&amp;gt;&amp;lt;sup&amp;gt;18&amp;lt;/sup&amp;gt;O record prediction of the monsoon boundary zone in the northern China

Based on high-resolution oxygen isotope records of stalagmites collected from Wanxiang and Huangye Caves, a prediction experiment for precipitation over the next 20 years is performed, using the time domain combined model. The study indicates that this model can be used to determine the significant period of the time series and fit the original record well. The prediction accords with modern meteorological observation, and it is thus credible to a certain extent. Compared with tree-ring prediction of the monsoon boundary zone in northern China, the result indicates that precipitation may reach a minimum during 2012-2013, and first increases and later decreases during the subsequent 20 years.

Changes in soil properties during reversal of desertification in agro-pastoral transition zone of Northern China

Based on the field surveys and laboratory analysis, soil physical, chemical and biological properties were studied at different degrees of the reversal of desertification in the agro-pastoral transition zone of northern China. The resultsobtained show that with the consequence of mobile sand land →semimobile sand land →semi-fixed sand land →fixed sand land, the dominant soil particle size changed from coarse sand to a combination of fine sand and silt + clay, and corresponding levels of each soil nutrient increased. The content of coarse sand (>0.25 mm) was significantly and negatively correlated with soil nutrient contents, whereas nutrient contents were significantly and positively correlated with the contents of fine sand (0.25 to 0.02 mm) and silt + clay (<0.02 mm). The increasingly fine soil texture and the nutrient enrichment both facilitated rehabilitation of desertified land. The path analysis showed that soil organic matter was the main factor that affected soil enzymes activities directly while total potassium (P) was less important. Principal-components analysis (PCA) revealed that the soil quality tend to increase during the reversal process and that biological factor were more significant than nutrient factors and particle size. Fine sand was the most important particle factors.

Synthesis, Characterization, and Oil Recovery Application of Biosurfactant Produced by Indigenous Pseudomonas aeruginosa WJ-1 Using Waste Vegetable Oils

A bacterial strain was isolated and cultured from the oil excavation areas in tropical zone in northern China. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, WJ-1, was identical to those of cultured representatives of the species Pseudomonas aeruginosa. This bacterium was able to produce a type of biosurfactant. Compositional analysis revealed that the extracted biosurfactant was composed of high percentage lipid (∼74%, w/w) and carbohydrate (∼20%, w/w) in addition to a minor fraction of protein (∼6%, w/w). The best production of 50.2g/l was obtained when the cells were grown on minimal salt medium containing 6.0% (w/v) glucose and 0.75% (w/v) sodium nitrate supplemented with 0.1% (v/v) element solution at 37°C and 180rpm after 96h. The optimum biosurfactant production pH value was found to be 6.0-8.0. The biosurfactant of WJ-1, with the critical micelle concentration of 0.014g/L, could reduce surface tension to 24.5mN/m and emulsified kerosene up to EI(24) ≈95. The results obtained from time course study indicated that the surface tension reduction and emulsification potential was increased in the same way to cell growth. However, maximum biosurfactant production occurred and established in the stationary growth phase (after 90h). Thin layer chromatography, Fourier transform infrared spectrum, and mass spectrum analysis indicate the extracted biosurfactant was affiliated with rhamnolipid. The core holder flooding experiments demonstrated that the oil recovery efficiency of strain and its biosurfactant was 23.02% residual oil.

Storage, Patterns and Controls of Soil Nitrogen in China

Soil holds the largest nitrogen (N) pool in terrestrial ecosystems, but estimates of soil N stock remain controversial. Storage and spatial distribution of soil N in China were estimated and the relationships between soil N density and environmental factors were explored using data from China's Second National Soil Survey and field investigation in northwest China and the Tibetan Plateau. China's soil N storage at a depth of one meter was estimated at 7.4 Pg, with an average density of 0.84 kg m −2. Soil N density appeared to be high in southwest and northeast China and low in the middle areas of the country. Soil N density increased from the arid to semi-arid zone in northern China, and decreased from cold-temperate to tropical zone in the eastern part of the country. An analysis of general linear model suggested that climate and vegetation determined the spatial pattern of soil N density for natural vegetation, which explained 75.4% of the total variance.

Problems and strategies for sustainable development of farming and animal husbandry in the Agro-Pastoral Transition Zone in Northern China (APTZNC)

The Agro-Pastoral Transition Zone in Northern China (APTZNC) is one of the world's distinct ecological ecotones, covering 69 × 104 km2 and having a population of approximately 6.7 × 107. The location of the APTZNC reflects its importance as a vast natural ecological shelterbelt, with an important role in national environmental protection. However, in recent years, the APTZNC has been seriously damaged do to overgrazing and reclamation disturbances, thus endangering the development of farming and animal husbandry and threatening national ecological security. The Chinese State Council issued a paper on 'Construct Planning of the National Environment' that confirmed the region as one of four priority areas for consideration by 2010. The results of the present study indicate that heavy population pressure and overgrazing are the main causes for ecological deterioration, and that desertification is the primary obstacle that limits farming and livestock production. The implementation of an ecological population emigration policy, regulation of farming ecosystem structure to forage and grass cultivation, and adjusting the agricultural central production value from farming to livestock breeding are essential strategies required to harmonise agricultural development and ecological protection.

Storage, patterns and environmental controls of soil organic carbon in China

Based on the data from China’s second national soil survey and field observations in northwest China, we estimated soil organic carbon (SOC) storage in China and investigated its spatial and vertical distribution. China’s SOC storage in a depth of 1 meter was estimated as 69.1 Pg (1015 g), with an average density of 7.8 kg m−2. About 48% of the storage was concentrated in the top 30 cm. The SOC density decreased from the southeast to the northwest, and increased from arid to semi-humid zone in northern China and from tropical to cold-temperate zone in the eastern part of the country. The vertical distribution of SOC differed in various climatic zones and biomes; SOC distributed deeper in arid climate and water-limited biomes than in humid climate. An analysis of general linear model suggested that climate, vegetation, and soil texture significantly influenced spatial pattern of SOC, explaining 78.2% of the total variance, and that climate and vegetation interpreted 78.9% of the total variance in the vertical SOC distribution.

Dynamics of soil physical and chemical properties and vegetation succession characteristics during grassland desertification under sheep grazing in an agro-pastoral transition zone in Northern China

A number of field experiments were conducted from 1986 to 2003 to investigate the dynamics of soil physical and chemical properties as well as vegetation succession characteristics during the grassland desertification process under sheep grazing. Results indicate that fine silt (0.01–0.001 mm) removal and medium sand (0.5–0.25 mm) increase occurred early in the desertification process resulting in coarser surface soil. The fine sand (0.25–0.05 mm) was the major (33.7–68.4%) soil fractions element throughout the process. Changes in soil fractions were associated with a decline in soil fertility as the natural grassland shifted to a desertified landscape. The organic matter concentration decreased significantly by 94%, 89% and 69%, respectively, in the 0–5, 5–10 and 10–30 cm soil layers. The desertification effects on total soil N followed the same trend as the organic matter. Total soil P and K concentrations decreased only slightly and were consistent early in the desertification process. Soil bulk density increased companied with the decline of soil porosity and compaction as the desertification process continued. Species diversity declined both in the plant community and the soil seed bank, and species richness decreased by 56%. Three successional stages were identified, with bunchgrass communities being the first, followed by the growth of rhizomous grasses, and then sandy species and annual plant communities. In conclusion, grassland desertification was accompanied by severe soil erosion, soil nutrition decline and species diversity losses.

Mongolian nomadic culture and ecological culture: On the ecological reconstruction in the agro-pastoral mosaic zone in Northern China

After analyzing the grassland environmental characteristics and nomads vs. agrarian land use styles and their ecological and environmental influences in the arid and semiarid agro-pastoral mosaic zone in northern China, it was concluded that Mongolian nomadic culture is more close to the basic principles of the ecological culture in the modern sense. Mongolian nomadic culture has advantages over agrarian culture in ecology and environmental care, sustainable utilization of grasslands, and in sustainable human social economic development in the region. Generally speaking nomadic culture prevents desertification; whereas, agrarian culture facilitates desertification. Confliction between nomadic protection and agrarian destruction of grassland ecosystem is essentially focused on the problem of regional and even global ecological safety. Obviously, protection of ecological safety should be given priority because human social and economic existence, as well as development depend on and are decided by the vulnerable ecological safety in the arid and semiarid areas. Therefore expansion of cropping into the fragile ecosystem of arid lands was unfortunate. The long term sustainable management of these grassland ecosystems could benefit from reversal of policies that are exacerbating the problems of land degradation, and from the adoption of land use practices that have been successfully applied for centuries by Mongolian herders. Protection of grasslands and nomadic culture is far more important or even vital to the subsistence and sustainability of human and all other beings, compared to the protection of agrarian lifestyle and land cultivation. Protection of ecologic safety is protecting the premise and fundamental bases of economic and social development in the area. It is important to derive the rational elements of nomadic culture in construction of ecological culture, and in the ecological reconstruction in northern China. Based on analyzing and reasoning in line with the quintessence of nomadic culture summarized, some proposals on ecological reconstruction in the area are presented.

Regionalisation of suitable herbages for grassland reconstruction in agro‐pastoral transition zone of northern China

To provide a sound basis for selecting suitable herbages for grassland reconstruction in the farming‐pastoral zone of northern China, the zone was divided into regions using the lowest annual temperature, water regimes represented by a moisture index (the ratio between annual rainfall and accumulated temperature >0°C), soil types, and terrain. Suitable herbages of Gramineae (G), Legu‐minosae (L) and other families (O), representing native species (NS) and non‐native cultivars (CR) were recommended for the zone based on the following four principles: a) matching species with the site; b) giving precedence to ecological conservation; c) providing economic benefit to production; and d) taking into account the integrity of local administrative division. The main findings from this study were as follows. The farming‐pastoral zone was divided into seven regions: I. Western Songliao Plain and Daxinganling Mountain Region; II. Upper Liaohe River Sandy Region; III. Mid‐Eastern Mongolia Plateau and Northwestern Heibei Mountain Region; IV. Luliang, Taihang and Yanshan Mountains Region; V. Ordos Plateau Sandy Region; VI. Northern Shaanxi to Eastern Ganxu Loess Plateau Region; and VII. Mid Gansu to Eastern Qinghai Plateau Loess Region. Among the herbages recommended for selection, Stipa grandis and Leymus chinensis were particularly suggested for controlling wind erosion in Region I; Leymus chinensis and Elymus dahuricus for lessening soil alkalisation in Region II; Stipa glareos, Elymus dahuricus and Agropyron deserto‐rum for retarding land desertification in Region III; Elymus nutans and Bromus inermis for preventing water erosion in Region IV; Agropyron desertorum and Elymus dahuricus for reducing wind erosion and land desertification for Region V; Medicago sativa and Onobrychis viciaefolia for improving soil fertility in Region VI; Medicago varia and Melilotoides rethenica for controlling erosion and improving soil fertility in Region VII.

Impact of land surface deg-radation in northern China and southern Mongolia on re-gional climate

Clear evidence provided by the singular value decomposition (SVD) analysis to the normalized difference vegetation index (NDVI) and precipitation data identifies that there exists a sensitive region of vegetation-climate interaction located in the transitional zone over northern China and its surrounding areas, where the vegetation cover change has the most significant influence on summer precipitation over China. Comparison of reanalysis data with station data provides a good method to assess the impacts of land use change on surface temperature, and the most obvious contribution of land use change may be to lead to notable warming over northern China in the interdecadal time scale. Based on the new statistical results, a high-resolution regional integrated environmental model system (RIEMS) is employed to investigate the effects of land surface degradation over the transitional zone and its surrounding areas (northern China and southern Mongolia) on the regional climate. Land degradation results in the decreases in precipitation over northern and southern China, and the increase in between, and increased and decreased temperature over vegetation change areas and the adjacent area to the south, respectively. Not only would it change the surface climate, but also bring the significant influence on the atmospheric circulation. Both the surface climate and circulation changes generally agree to the observed interdecadal anomalies over the last five decades. These integrated statistical and simulated results imply that land surface degradation over the transitional zone in northern China and its surrounding areas could be one of the main causes responsible for the climate anomalies over China, especially the drought over northern China.

Decadal-scale precipitation variations in arid and semiarid zones of northern China during the last 500 years

Regional decadal precipitation reconstructions for the arid and semi-arid zones of northern China were established by the use of different palaeoclimate archives such as ice-cores, tree-rings, lake sediments and written historical documents. Local rainfall reconstructions from single sites were averaged to obtain regional precipitation records for western and eastern regions of an arid and semiarid zone of northern China, respectively. All established regional precipitation curves display 5 dry periods, each lasting about 50 years. Meanwhile, precipitation reconstructions show regional dissimilarities. During the last 500 years, the trends of precipitation change in the eastern arid region are basically consistent with those in the western and eastern regions of the semiarid zone. Precipitation variations in the western arid region are unique, showing significant local patterns of rainfall variability. Maximum entropy method (MEM) spectral estimates show that each regional precipitation series contains stationary century-scale periodicities of about 120 a. Singular spectrum analysis was applied to isolating the century-scale oscillation signals from the regional proxy precipitation series. Significant periods with wavelengths of 121.4a, 154.6a, 124.3a, 118.6a, 108.5a and 121.4a were found 26.56%, 26.44%, 28.87%, 18.67%, 33.48% and 34.04% of the variances of the original series for the western arid zone, the eastern arid zone, the whole arid zone, the western semiarid zone, the eastern semiarid zone and whole northern China, respectively.

Sustainable Agriculture in the Semi-Arid Agro-Pastoral Interweaving Belt of Northern China

The semi-arid agro-pastoral interweaving belt (SAPIB) is an important ecological zone in northern China and an important food base. However, sustainable agricultural development has been restricted by both natural and socioeconomic factors. It is inherently vulnerable because of its unfavourable climate and geological and hydrogeomorphological conditions. Agricultural production has been impaired by frequent natural disasters, salinization and desertification. Moreover, irrational agricultural policies and practices, poverty and other socioeconomic factors have brought about degradation in the SAPIB. The authors argue that the basis for a sustainable strategy is to transform it by increasing exergy input, changing the cultural outlook and harmonizing interactions between the component subsystems. Finally, a series of proposals based on notions for a sustainable strategy is put forward.

Landscape change and desertification development in the Mu Us Sandland, Northern China

In order to document the status and causes of desertification development in the Mu Us Sandland located in the agro-pastoral transitional zone in northern China, we interpreted and analysed satellite images, historical maps, meteorological and socio-economic data to assess landscape change from the 1950s to the 1990s. During the intervening 35-year period, landscapes have changed significantly in this area. The shifting and semi-fixed sandy lands have increased by 540,915·3 and 399,302·2 ha, respectively, and now cover 44·53% and 21·44% of the area of the Mu Us Sandland, in the meantime the fixed sandy land has decreased by 572,130·6 ha and covers only 7·22% of the sandland. The rate of desertification in the middle and northwest, where there is only pasture, is much higher than that in the east and south, where farmland and pasture exist together. In most of the sandland, desertification has developed rapidly, while rehabilitation of vegetation has occurred only in marginal areas in the east and south. The main causes of desertification development in the Mu Us Sandland are intensified and irrational human activities, such as over-reclaiming, over-grazing and over-cutting.