Vegetation restoration through artificial plantation is an effective method to combat desertification,especially in arid and semi-arid areas.This study aimed to explore the ecological effect of the plantation of Sabin...Vegetation restoration through artificial plantation is an effective method to combat desertification,especially in arid and semi-arid areas.This study aimed to explore the ecological effect of the plantation of Sabina vulgaris on soil physical and chemical properties on the southeastern fringe of the Mu Us Sandy Land,China.We collected soil samples from five depth layers(0-20,20-40,40-60,60-80,and 80-100 cm)in the S.vulgaris plantation plots across four plantation ages(4,7,10,and 16 years)in November 2019,and assessed soil physical(soil bulk density,soil porosity,and soil particle size)and chemical(soil organic carbon(SOC),total nitrogen(TN),available nitrogen(AN),available phosphorus(AP),available potassium(AK),cation-exchange capacity(CEC),salinity,p H,and C/N ratio)properties.The results indicated that the soil predominantly consisted of sand particles(94.27%-99.67%),with the remainder being silt and clay.As plantation age increased,silt and very fine sand contents progressively rose.After 16 years of planting,there was a marked reduction in the mean soil particle size.The initial soil fertility was low and declined from 4 to 10 years of planting before witnessing an improvement.Significant positive correlations were observed for the clay,silt,and very fine sand(mean diameter of 0.000-0.100 mm)with SOC,AK,and p H.In contrast,fine sand and medium sand(mean diameter of 0.100-0.500 mm)showed significant negative correlations with these indicators.Our findings ascertain that the plantation of S.vulgaris requires 10 years to effectively act as a windbreak and contribute to sand fixation,and needs 16 years to improve soil physical and chemical properties.Importantly,these improvements were found to be highly beneficial for vegetation restoration in arid and semi-arid areas.This research can offer valuable insights for the protection and restoration of the vegetation ecosystem in the sandy lands in China.展开更多
Based on multi-temporal remotely sensed materials of both 1985 and 2000, we analyzed the effects of land-use types and their conversions on desertification in Mu Us Sandy Land in the agro-pastoral transitional zone of...Based on multi-temporal remotely sensed materials of both 1985 and 2000, we analyzed the effects of land-use types and their conversions on desertification in Mu Us Sandy Land in the agro-pastoral transitional zone of north central China. In this study, the desertified land was classified into five degrees: potential, light, medium, severe and extreme. The results indicate that the extent of desertification expands slightly, while desertification degree is enhanced significantly. About 22.35% of the total land area in the study area is in the desertification course, and the expanded area of both severely and extremely desertified land accounts for 3.67% of the total area of Mu Us Sandy Land. About 9053 klTl2 of area witnessed changes in land-use types between 1985 and 2000, which accounted for 10.75% of the total. More importantly, the area of conversions among cultivated land, forestland and rangeland added up to 971.6 km^2. This research reveals that both improper land-use types and conversions could accelerate the desertification process. Both cultivated land and forestland have more effects on the desertification development than rangeland. Some land-use type conversions, such as rangeland to cultivated land, rangeland to forestland and forestland to cultivated land, are attributed to the acceleration of the desertification development while the opposite can control the desertification development.展开更多
Desertification reversion is an interactive process involving climate, land use change, and water processes. In order to reveal the relationship between desertification reversion and these factors, we analyzed histori...Desertification reversion is an interactive process involving climate, land use change, and water processes. In order to reveal the relationship between desertification reversion and these factors, we analyzed historical data on precipitation, air temperature, desertified land changes, underground water tables, and water body changes in Naiman County in the central part of Horqin Sandy Land. Our analysis showed that during 1961-2010 the annual precipitation fluctuated dramatically and has decreased fairly consistently in recent years. The air temperature increased by 0.50-1.25℃, and the minimum temperature increased more obviously. The desertified land area increased from 42,300 km^2 in 1959 to 62,000 km^2 in 1985, and then declined to about 50,000 km^2 in 2010. The underground water tables have been lowered by about 10 m in the past 30 years, and declined more rapidly in recent years. Desertified land is significantly related to the amount of total cropland, and underground water tables are signifcantly correlated with annual precipitation and the amount of irrigated cropland. Therefore, it is necessary to pursue sustainable desertification reversion without compromising the capacity for local development and restoration of degraded land, through application of appropriate management measures for improving water availability in this region.展开更多
Otindag Sandy Land in China is an important ecological barrier to Beijing;the changes in its ecological quality are major concerns for sustainable development and planning of this area.Based on principal component ana...Otindag Sandy Land in China is an important ecological barrier to Beijing;the changes in its ecological quality are major concerns for sustainable development and planning of this area.Based on principal component analysis and path analysis,we first generated a modified remote sensing ecological index(MRSEI)coupled with satellite and ground observational data during 2001–2020 that integrated four local indicators(greenness,wetness,and heatness that reflect vegetation status,water,and heat conditions,respectively,as well as soil erosion).Then,we assessed the ecological quality in Otindag Sandy Land during 2001–2020 based on the MRSEI at different time scales(i.e.,the whole year,growing season,and non-growing season).MRSEI generally increased with an upward rate of 0.006/a during 2001–2020,with clear seasonal and spatial variations.Ecological quality was significantly improved in most regions of Otindag Sandy Land but degraded in the southern part.Regions with ecological degradation expanded to 18.64%of the total area in the non-growing season.The area with the worst grade of MRSEI shrunk by 15.83%of the total area from 2001 to 2020,while the area with the best grade of MRSEI increased by 9.77%of the total area.The temporal heterogeneity of ecological conditions indicated that the improvement process of ecological quality in the growing season may be interrupted or deteriorated in the following non-growing season.The implementation of ecological restoration measures in Otindag Sandy Land should not ignore the seasonal characteristics and spatial heterogeneity of local ecological quality.The results can explore the effectiveness of ecological restoration and provide scientific guides on sustainable development measures for drylands.展开更多
Historical desertification of the Mu Us Sandy Land is linked to both environmental changes and anthropogenic activities. This paper reports on an analysis of grain size parameters as indicative of such changes in the ...Historical desertification of the Mu Us Sandy Land is linked to both environmental changes and anthropogenic activities. This paper reports on an analysis of grain size parameters as indicative of such changes in the southwestern area of the Mu Us Sandy Land. Combined with analysis of chronologies and historical records, our results indicate that Beidachi Lake and a nearby season- al river have retreated continuously in history and that sand dunes appeared at approximately the end of the Ming dynasty. This study sheds new light on the understanding of spatial-temporal changes of the interior Mu Us Sandy Land in history and has great significance in revealing environmental changes of the interior region of the Mu Us Sandy Land.展开更多
China is a country largely affected by desertification.The main purpose of this article is to analyze interannual and seasonal changes in fractional vegetation cover(FVC)in the Mu Us Sandy Land(MUSL).It uses fused rem...China is a country largely affected by desertification.The main purpose of this article is to analyze interannual and seasonal changes in fractional vegetation cover(FVC)in the Mu Us Sandy Land(MUSL).It uses fused remote sensing data to quantitatively analyze the response of FVC to climate change and human activities.The results showed that desertification in the MUSL had improved over the past 20 years.Grade V desertification decreased from more than 60%in 2000 to about 15%in 2020.In some years,degradation appeared to be affected by climate factors and human activity,especially in the northwestern portion of the study area.The FVC in summer was slightly higher than that in autumn and far higher than recorded in spring and winter.Spatially,the northwestern and central parts of the study area were unstable,with high coefficients of variation.FVC gradually increased from northwest to southeast,and areas with the fastest increase in FVC were concentrated along the eastern and southern edges of the study area.The correlations between FVC and precipitation and dryness were slightly pos-itive,but the correlation between FVC and temperature showed regional differences.The increase of population density is not a key factor limiting the growth of vegetation;the policy of“grazing prohibition,grazing rest,and rotational grazing”has allowed the restoration of vegetation;and afforestation is an effective way to promote the increase in FVC.展开更多
[Objectives]The paper was to investigate the distribution characteristics of soil total nitrogen in low-efficiency forest land in the northern windy desert area of Jingbian County.[Methods]The distribution of soil tot...[Objectives]The paper was to investigate the distribution characteristics of soil total nitrogen in low-efficiency forest land in the northern windy desert area of Jingbian County.[Methods]The distribution of soil total nitrogen in the 0-40 cm soil layer of 5 towns in the northern windy desert area of Jingbian County was studied through field sampling and laboratory detection.[Results]The average soil total nitrogen contents of Hongdunjie Town,Haizetan Town,Huanghaojie Town,Ningtiaoliang Town,Dongkeng Town and windy desert area in the 0-20 cm soil layer were 0.259,0.224,0.242,0.248,0.431 and 0.275 g/kg,respectively.The soil total nitrogen content in Dongkeng Town was higher than those in other towns,while there was little difference among other regions.The average total nitrogen contents in the 20-40 cm soil layer were 0.239,0.285,0.113,0.262,0.349 and 0.241 g/kg,respectively.The soil total nitrogen content in Huanghaojie Town was slightly lower than those in other towns,while that in Dongkeng town was higher.The variation coefficient of soil total nitrogen content in the survey area was greater than 30%,and there was great difference in spatial distribution.With the increase of soil depth,there was little change in soil total nitrogen content,namely the soil total nitrogen contents in 5 towns and windy desert area were not statistically different in the 0-40 cm soil layer.According to the nutrient grading standard of the second national soil survey,the soil total nitrogen content in the survey area was in the deficiency grade.[Conclusions]The research will provide a scientific guidance for the healthy and sustainable development of vegetation in arid regions.展开更多
This experiment was conducted in three sites along a desertification gradient in Horqin Sandy Land, Northern China. Soils una-mended and amended with five types of plant residue in a wide range of C:N ratios from 9.9...This experiment was conducted in three sites along a desertification gradient in Horqin Sandy Land, Northern China. Soils una-mended and amended with five types of plant residue in a wide range of C:N ratios from 9.9 to 82.2 were incubated for 70 days, during which C and N mineralization were measured. Along the desertification gradient from fixed sand dune to semifixed, and mobile sand dune: cumulative CO2-C produced from the unamended soils was 231.6, 193.3 and 61.9 μg/g, respectively, while net inorganic N was 22.9, 17.6 and 0.9 mg/kg. Soils amended with residues produced more CO2-C than the unamended soils across all sites. During the first 10 days, C mineralization rate of residue-amended soils decreased with the increase of C:N ratio at each site. However, the mineralization rates were poorly correlated with the C:N ratio in subsequent stage of incubation. Soils of mobile sand dune amended with higher C:N ratio (more than 32) residues produced less CO2-C than that of fixed and semifixed sand dune. NO3--N was the predominant form of inorganic N during the mineralization process in sandy soils. Carbon-to-nitrogen ratio (C:N) can be regarded as a predictor of the speed of N mineralization in sandy soil. The more C. microphylla residue with the lowest C:N ratio (9.9) added in soils, the more net inorganic N released. Our results suggest that C. microphylla residue when added to soil would potentially provide short-term plant available N and improve the soil quality in sandy land. The desertification process postponed the release of inorganic N from plant residues.展开更多
Songnen Sandy Land lies in the eastern fringe of huge sandy belt of middle latitude inEurasia Continent Here is also the eastern fringe of desertification-prone land in China. Its specialconditions such as biology and...Songnen Sandy Land lies in the eastern fringe of huge sandy belt of middle latitude inEurasia Continent Here is also the eastern fringe of desertification-prone land in China. Its specialconditions such as biology and climate, the history of evolution of sandy land and its location make itpossess features differing from other sandy lands in the country. This article systematitaly discussesthe regional featured such as the historical process, modern process, environmental factors ondesertification and the sandy land landscape and the degree of desertification, and raises some advicesfor rehabilitation and development in this area.展开更多
Samples from the Horqin sandy land were exposed to a series of wind velocities,and sink particles were collected at the end of the diffusion section of a wind tunnel.Grain sizes of collected samples show great variati...Samples from the Horqin sandy land were exposed to a series of wind velocities,and sink particles were collected at the end of the diffusion section of a wind tunnel.Grain sizes of collected samples show great variation because of the granularity difference of the surface samples.The original samples show lower average content of SiO_(2) and higher average content of Al _(2)O_(3),Fe_(2)O_(3),MgO,CaO,Na_(2)O,and K_(2)O than collected samples.Compared with other dust source areas in China,the Horqin sandy land had higher content of Zr,Ba,SiO_(2),Al_(2)O_(3) and K_(2)O.Compared with the average upper continental crust(UCC)composition,surface samples were rich in the content of Y,Zr,Nb,Ba,La,Nd.Geochemistry characteristics of fine grain components of the Horqin sandy land differ from those from other dust source regions,because fine-grained particles in the Horqin sandy land were mostly derived from various local deposits formed in its unique depositional environments influenced by several tectonic activities.展开更多
Large areas of Artemisia ordosica Krasch., Caragana korshinskii Kom., and Caragana intermedia Kuang and H. C. Fu plantations were established on moving sand dunes in the Gonghe Basin (northeastern Tibetan Plateau) f...Large areas of Artemisia ordosica Krasch., Caragana korshinskii Kom., and Caragana intermedia Kuang and H. C. Fu plantations were established on moving sand dunes in the Gonghe Basin (northeastern Tibetan Plateau) for vegetation restoration. Elevating our understanding of the changes in soil characteristics after the establishment of different plantation types can be useful in the context of combating deserdfication. To assess the effects of these plantation types on the restoration of sandy land, we measured soil physical-chemical properties at four depths (0-5, 5-10, 10-20, and 20-50 cm) in each of the three plantation types and also in non-vegetated moving sand dunes (as control sites). Generally, the establishment of A. ordosica, C korshinskii and C intermedia plantations on sand dunes has greatly ameliorated soil quality in the Gonghe Basin. Specifically, relative to the moving sand dunes, shrub plantation has increased the silt and clay contents, total porosity and water holding capacity, soil organic matter, total nitrogen, total phosphorus and total potassium contents. The calculated soil quality index suggested that in the Gonghe Basin, C. intermedia is the best choice for soil amelioration. In all the three plantation types, soil amelioration mainly occurred in the shallow depths.展开更多
Improving and validating land surface models based on integrated observations in deserts is one of the challenges in land modeling. Particularly, key parameters and parameterization schemes in desert regions need to b...Improving and validating land surface models based on integrated observations in deserts is one of the challenges in land modeling. Particularly, key parameters and parameterization schemes in desert regions need to be evaluated in-situ to improve the models. In this study, we calibrated the land-surface key parameters and evaluated several formulations or schemes for thermal roughness length (z 0h ) in the common land model (CoLM). Our parameter calibration and scheme evaluation were based on the observed data during a torrid summer (29 July to 11 September 2009) over the Taklimakan Desert hinterland. First, the importance of the key parameters in the experiment was evaluated based on their physics principles and the significance of these key parameters were further validated using sensitivity test. Second, difference schemes (or physics-based formulas) of z 0h were adopted to simulate the variations of energy-related variables (e.g., sensible heat flux and surface skin temperature) and the simulated variations were then compared with the observed data. Third, the z 0h scheme that performed best (i.e., Y07) was then selected to replace the defaulted one (i.e., Z98); the revised scheme and the superiority of Y07 over Z98 was further demonstrated by comparing the simulated results with the observed data. Admittedly, the revised model did a relatively poor job of simulating the diurnal variations of surface soil heat flux, and nighttime soil temperature was also underestimated, calling for further improvement of the model for desert regions.展开更多
Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however the information on how dune stabilization influences the spatial scale dependence of plant diversity is still la...Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however the information on how dune stabilization influences the spatial scale dependence of plant diversity is still lacking. In this study, we measured the plant species richness, soil properties and altitude across four spatial scales (1, 10, 100 and 1,000 m2) at three different dune stabilization stages (mobile dune, semi-fixed dune and fixed dune) in Horqin Sandy Land, Northern China. We also examined the relationships between plant species richness, community composition and environmental factors along the gradient of dune stabilization. Our results showed that plant species richness increased with the increase of spatial scales in each dune stabilization stage, as well as with the increase of dune stabilization degrees. Canonical correspondence analysis (CCA) showed that plant distribu- tions in the processes of dune stabilization were determined by the combined environmental gradient in relation to soil organic carbon (SOC), total nitrogen (TN), carbon/nitrogen (C/N), pH, electrical conductivity (EC), soil water content (SWC), fine sand (FS), very fine sand (VFS), silt and clay (SC), and altitude. Plant species richness was significantly and positively correlated to SOC and TN in mobile dune, and significantly and positively correlated to SOC, TN, C/N, VFS and SC in semi-fixed dune. However, no significant correlation between plant species richness and environmental factors was observed in fixed dune. In addition, plant species richness in different dune stabili- zation stages was also determined by the combined gradient of soil properties and altitude. These results suggest that plant species richness has obvious scale dependence along the gradient of dune stabilization. Soil resources depending on dune habitats and environmental gradients caused by dune stabilization are important factors to de- termine the scale dependence of species diversity in sand dune ecosystems.展开更多
Remote sensing is a valuable and effective tool for monitoring and estimating aboveground biomass (AGB) in large areas.The current international research on biomass estimation by remote sensing technique mainly focu...Remote sensing is a valuable and effective tool for monitoring and estimating aboveground biomass (AGB) in large areas.The current international research on biomass estimation by remote sensing technique mainly focused on forests,grasslands and crops,with relatively few applications for desert ecosystems.In this paper,Landsat Thematic Mapper (TM)/Enhanced Thematic Mapper Plus (ETM+) images from 1988 to 2007 and the data of 283 AGB samples in August 2007 were used to estimate the AGB for Mu Us Sandy Land over the past 30 years.Moreover,temporal and spatial distribution characteristics of AGB and influencing factors of climate and underlying surface were also studied.Results show that:(1) Differences of correlations exist in the fitted equations between AGB and different vegetation indices in desert areas.The modified soil adjusted vegetation index (MSAVI) and soil adjusted vegetation index (SAVI) show relatively higher correlations with AGB,while the correlation between normalized difference vegetation index (NDVI) and AGB is relatively lower.Error testing shows that the AGB-MSAVI model established can be used to accurately estimate AGB of Mu Us Sandy Land in August.(2) AGB in Mu Us Sandy Land shows the fluctuant characteristics over the past 30 years,which decreased from the 1980s to the 1990s,and increased from the 1990s to 2007.AGB in 2007 had the highest value,with a total AGB of 3.352×106 t.Moreover,in the 1990s,AGB had the lowest value with a total AGB of 2.328×106 t.(3) AGB with relatively higher values was mainly located in the middle and southern parts of Mu Us Sandy Land in the 1980s.AGB was low in the whole area in the1990s,and relatively higher AGB values were mainly located in the southern parts of Uxin.In 2007,AGB in the whole area was relatively higher than those of the last twenty years,and higher AGB values were mainly located in the northern,western and middle parts of Mu Us Sandy Land.展开更多
Aeolian deposits from the deserts in northern China have been used for palaeoenvironmental research to understand aeolian sedimentology and its dynamic connection to past climate conditions. The Tengger Desert in Chin...Aeolian deposits from the deserts in northern China have been used for palaeoenvironmental research to understand aeolian sedimentology and its dynamic connection to past climate conditions. The Tengger Desert in China is sensitive to the waxing and waning of the monsoonal system. In response to past climate change, the southern margin of the Tengger Desert has evolved significantly since the last glacial period. However, previous attempts to date aeolian deposits in this region were mainly based on radiocarbon dating, which has problems when applied to aeolian deposits. Moreover, sedimentary records are limited. Accordingly, past aeolian activity in this desert remains poorly understood. In the present study, we dated sand samples from Gulang county at the southern margin of the Tengger Desert using optically stimulated luminescence (OSL) to understand the history of aeolian activity in this region. Our samples represented well-sorted aeolian sands and sandy loess. Aeolian sands are evidence of dune field buildup and sparse vegetation cover whereas sandy loess is evidence of improved stabilization of sand dunes resulting from ameliorated vegetation cover. Certain samples showed a decline in the equivalent dose (D<sub> e </sub>) values when successive integration intervals were applied, which resulted from unstable OSL signals from non-fast components in the initial part of the decay curve. In order to obtain reliable D<sub> e </sub> estimates, we investigated component-resolved and different background subtraction approaches, and compared the resultant D<sub> e </sub> estimates. We adopted the early background subtraction method to derive D<sub> e </sub> values. Luminescence chronologies and sedimentary records indicated that sand dunes accumulation occurred before 10 ka, and sandy loess developed between 9.5 and 7.6 ka when sand dunes were stabilized as a result of increased effective moisture levels. The transition between sand dune mobilization and stabilization emphasizes the significance of an effective moisture threshold in controlling aeolian activity. Mobilization of sand dunes at ~2.3 ka might be related to an increased aridity during the Late Holocene.展开更多
This study investigated the distribution pattern of biological soil crust (BSC) in Artemisia ordosica communities in Mu Us Sandy Land. Three experimental sites were selected according to grazing pressure gradient. I...This study investigated the distribution pattern of biological soil crust (BSC) in Artemisia ordosica communities in Mu Us Sandy Land. Three experimental sites were selected according to grazing pressure gradient. In each experimental site, the total vegetation cover, A. ordosica cover, BSC cover, litter-fall cover, BSC degree of fragmentation, BSC thickness and soil properties were investigated in both fixed and semi-fixed sand dunes and simultaneously analyzed in the laboratory. The results showed that at the same grazing pressure, BSC cover and composition were significantly affected by the fixation degree of sand dunes. In addition, BSC cover in the fixed sand dunes was 83.74% on average, whereas it is proportionally dominated by 28% mosses, 21% lichens, and 51% algae. Meanwhile, BSC cover in the semi-fixed sand dunes was 23.54% on average, which is proportionally domi- nated by 6.3% mosses, 2.5% lichens, and 91.2% algae. Fine sand, organic matter, and total nitrogen (N) contents in the fixed sand dunes were all significantly higher than those in the semi-fixed sand dunes. Litter-fall cover de- creased along the grazing pressure gradient, whereas BSC fragmentation degree increased. Fine sand content decreased along with the increase of grazing pressure, whereas medium sand content increased in both fixed and semi-fixed dunes. The organic matter and total N contents in the no grazing site were significantly higher than those in light and normal grazing sites. However, there were no significant differences between the light and normal grazing sites. In addition, there were also no significant differences in BSC thickness between the light and normal grazing sites in the fixed sand dunes. However, a significant decrease was observed in both BSC cover and thick- ness in the normal grazing site. The BSC in the semi-fixed dunes was more sensitive to disturbance.展开更多
Soil water is the main form of water in desert areas, and its primary source is precipitation, which has a vital impact on the changes in soil moisture and plays an important role in deep soil water recharge(DSWR) in ...Soil water is the main form of water in desert areas, and its primary source is precipitation, which has a vital impact on the changes in soil moisture and plays an important role in deep soil water recharge(DSWR) in sandy areas. This study investigated the soil water response of mobile sand dunes to precipitation in a semi-arid sandy area of China. Precipitation and soil moisture sensors were used to simultaneously monitor the precipitation and the soil water content(SWC) dynamics of the upper 200-cm soil layer of mobile sand dunes located at the northeastern edge of the Mu Us Sandy Land of China in 2013. The data were used to analyze the characteristics of SWC, infiltration, and eventually DSWR. The results show that the accumulated precipitation(494 mm) from April 1 to November 1 of 2013 significantly influenced SWC at soil depths of 0-200 cm. When SWC in the upper 200-cm soil layer was relatively low(6.49%), the wetting front associated with53.8 mm of accumulated precipitation could reach the 200-cm deep soil layer. When the SWC of the upper 200-cm soil layer was relatively high(10.22%), the wetting front associated with the 24.2 mm of accumulated precipitation could reach the upper 200-cm deep soil layer. Of the accumulated 494-mm precipitation in 2013, 103.2 mm of precipitation eventually became DSWR, accounting for 20.9% of the precipitation of that year. The annual soil moisture increase was 54.26 mm in 2013. Accurate calculation of DSWR will have important theoretical and practical significance for desert water resources assessment and ecological construction.展开更多
Shrub presence has an important effect on the structuring of ground beetles in desert ecosystems. In this study, in order to determine how shrubs and different species influence ground beetle assemblages in a sandy de...Shrub presence has an important effect on the structuring of ground beetles in desert ecosystems. In this study, in order to determine how shrubs and different species influence ground beetle assemblages in a sandy desert scrubland dominated by two different shrub species, namely Calligonum mongolicum and Nitraria sphaerocarpa, we sampled the ground beetles using pitfall traps during spring, summer and autumn in 2012. At the community level, the activity density of the ground beetles was shown to be significantly higher under shrubs than in intershrub bare habitats in spring; but an opposite pattern occurred in autumn, suggesting the presence of sea- son-specific shrub effects on the activity density of the ground beetles. Meanwhile, at the trophic group level, the activity density and species richness of predators were significantly greater under shrubs than in intershrub bare habitats in spring, whereas an opposite trend occurred on the activity density in autumn. N. sphaerocarpa shrubs had a positive effect on the activity density of herbivores in the three seasons, and C. mongolicum shrubs had a positive effect on the activity density of detritivores in spring and autumn. At the species level, more Microdera sp. was captured under shrubs than in intershrub bare habitats in spring. During the same time, we also found that C. mongolicum shrubs had a positive effect on Blaps gobiensis in spring, Carabus sp. in autumn, and Tentyria sp. in spring and autumn, and N. sphaerocarpa shrubs had a positive effect on Cyphogenia chinensis, Sternoplax setosa in spring and summer, and Curculionidae sp. 1 in summer and autumn. The study results suggest that shrub presence, shrub species and season variation are important factors for ground beetle assemblages in this desert ecosystem, but the responses of beetles differed among trophic and taxonomic levels.展开更多
基金funded by the National Natural Science Foundation of China(42171004)the Key Research and Development Program in Shaanxi Province,China(2021ZDLSF05-02)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0403)。
文摘Vegetation restoration through artificial plantation is an effective method to combat desertification,especially in arid and semi-arid areas.This study aimed to explore the ecological effect of the plantation of Sabina vulgaris on soil physical and chemical properties on the southeastern fringe of the Mu Us Sandy Land,China.We collected soil samples from five depth layers(0-20,20-40,40-60,60-80,and 80-100 cm)in the S.vulgaris plantation plots across four plantation ages(4,7,10,and 16 years)in November 2019,and assessed soil physical(soil bulk density,soil porosity,and soil particle size)and chemical(soil organic carbon(SOC),total nitrogen(TN),available nitrogen(AN),available phosphorus(AP),available potassium(AK),cation-exchange capacity(CEC),salinity,p H,and C/N ratio)properties.The results indicated that the soil predominantly consisted of sand particles(94.27%-99.67%),with the remainder being silt and clay.As plantation age increased,silt and very fine sand contents progressively rose.After 16 years of planting,there was a marked reduction in the mean soil particle size.The initial soil fertility was low and declined from 4 to 10 years of planting before witnessing an improvement.Significant positive correlations were observed for the clay,silt,and very fine sand(mean diameter of 0.000-0.100 mm)with SOC,AK,and p H.In contrast,fine sand and medium sand(mean diameter of 0.100-0.500 mm)showed significant negative correlations with these indicators.Our findings ascertain that the plantation of S.vulgaris requires 10 years to effectively act as a windbreak and contribute to sand fixation,and needs 16 years to improve soil physical and chemical properties.Importantly,these improvements were found to be highly beneficial for vegetation restoration in arid and semi-arid areas.This research can offer valuable insights for the protection and restoration of the vegetation ecosystem in the sandy lands in China.
基金National Natural Science Foundation of China, No.40171040Knowledge Innovation Project of theInstitute of Geographic Sciences and Natural Resources Research, CAS, No.CXIOG-A02-03
文摘Based on multi-temporal remotely sensed materials of both 1985 and 2000, we analyzed the effects of land-use types and their conversions on desertification in Mu Us Sandy Land in the agro-pastoral transitional zone of north central China. In this study, the desertified land was classified into five degrees: potential, light, medium, severe and extreme. The results indicate that the extent of desertification expands slightly, while desertification degree is enhanced significantly. About 22.35% of the total land area in the study area is in the desertification course, and the expanded area of both severely and extremely desertified land accounts for 3.67% of the total area of Mu Us Sandy Land. About 9053 klTl2 of area witnessed changes in land-use types between 1985 and 2000, which accounted for 10.75% of the total. More importantly, the area of conversions among cultivated land, forestland and rangeland added up to 971.6 km^2. This research reveals that both improper land-use types and conversions could accelerate the desertification process. Both cultivated land and forestland have more effects on the desertification development than rangeland. Some land-use type conversions, such as rangeland to cultivated land, rangeland to forestland and forestland to cultivated land, are attributed to the acceleration of the desertification development while the opposite can control the desertification development.
基金funded by the National Pivotal Project,Nos.2011BAC07B02 and 201109025(2)NSFC Project No.41071185
文摘Desertification reversion is an interactive process involving climate, land use change, and water processes. In order to reveal the relationship between desertification reversion and these factors, we analyzed historical data on precipitation, air temperature, desertified land changes, underground water tables, and water body changes in Naiman County in the central part of Horqin Sandy Land. Our analysis showed that during 1961-2010 the annual precipitation fluctuated dramatically and has decreased fairly consistently in recent years. The air temperature increased by 0.50-1.25℃, and the minimum temperature increased more obviously. The desertified land area increased from 42,300 km^2 in 1959 to 62,000 km^2 in 1985, and then declined to about 50,000 km^2 in 2010. The underground water tables have been lowered by about 10 m in the past 30 years, and declined more rapidly in recent years. Desertified land is significantly related to the amount of total cropland, and underground water tables are signifcantly correlated with annual precipitation and the amount of irrigated cropland. Therefore, it is necessary to pursue sustainable desertification reversion without compromising the capacity for local development and restoration of degraded land, through application of appropriate management measures for improving water availability in this region.
基金the financial support given by the Special Funds for Science and Technology Innovation on Carbon Peak Carbon Neutral of Jiangsu Province,China(BK20220017)the Innovation Development Project of China Meteorological Administration(CXFZ2023J073)the National Key R&D Program of China(2018YFC1506606).
文摘Otindag Sandy Land in China is an important ecological barrier to Beijing;the changes in its ecological quality are major concerns for sustainable development and planning of this area.Based on principal component analysis and path analysis,we first generated a modified remote sensing ecological index(MRSEI)coupled with satellite and ground observational data during 2001–2020 that integrated four local indicators(greenness,wetness,and heatness that reflect vegetation status,water,and heat conditions,respectively,as well as soil erosion).Then,we assessed the ecological quality in Otindag Sandy Land during 2001–2020 based on the MRSEI at different time scales(i.e.,the whole year,growing season,and non-growing season).MRSEI generally increased with an upward rate of 0.006/a during 2001–2020,with clear seasonal and spatial variations.Ecological quality was significantly improved in most regions of Otindag Sandy Land but degraded in the southern part.Regions with ecological degradation expanded to 18.64%of the total area in the non-growing season.The area with the worst grade of MRSEI shrunk by 15.83%of the total area from 2001 to 2020,while the area with the best grade of MRSEI increased by 9.77%of the total area.The temporal heterogeneity of ecological conditions indicated that the improvement process of ecological quality in the growing season may be interrupted or deteriorated in the following non-growing season.The implementation of ecological restoration measures in Otindag Sandy Land should not ignore the seasonal characteristics and spatial heterogeneity of local ecological quality.The results can explore the effectiveness of ecological restoration and provide scientific guides on sustainable development measures for drylands.
基金supported by National Natural Science Foundation of China (41101187)the Specialized Research Fund for the Doctoral Program of Higher Education (20100211120006)+2 种基金the Ministry of Education, Humanities and Social Science Projects (10YJCZH053)the Fundamental Research Funds for the Central Universities (LZUJBKY-2012-136)the National Science Foundation for Post-Doctoral Scientists of China (2012M512051)
文摘Historical desertification of the Mu Us Sandy Land is linked to both environmental changes and anthropogenic activities. This paper reports on an analysis of grain size parameters as indicative of such changes in the southwestern area of the Mu Us Sandy Land. Combined with analysis of chronologies and historical records, our results indicate that Beidachi Lake and a nearby season- al river have retreated continuously in history and that sand dunes appeared at approximately the end of the Ming dynasty. This study sheds new light on the understanding of spatial-temporal changes of the interior Mu Us Sandy Land in history and has great significance in revealing environmental changes of the interior region of the Mu Us Sandy Land.
基金This work was supported by the National Natural Science Foundation of China(Grant No.41871231)and the National Key Research and Development Program of China(Grant No.2016YFB0501502).
文摘China is a country largely affected by desertification.The main purpose of this article is to analyze interannual and seasonal changes in fractional vegetation cover(FVC)in the Mu Us Sandy Land(MUSL).It uses fused remote sensing data to quantitatively analyze the response of FVC to climate change and human activities.The results showed that desertification in the MUSL had improved over the past 20 years.Grade V desertification decreased from more than 60%in 2000 to about 15%in 2020.In some years,degradation appeared to be affected by climate factors and human activity,especially in the northwestern portion of the study area.The FVC in summer was slightly higher than that in autumn and far higher than recorded in spring and winter.Spatially,the northwestern and central parts of the study area were unstable,with high coefficients of variation.FVC gradually increased from northwest to southeast,and areas with the fastest increase in FVC were concentrated along the eastern and southern edges of the study area.The correlations between FVC and precipitation and dryness were slightly pos-itive,but the correlation between FVC and temperature showed regional differences.The increase of population density is not a key factor limiting the growth of vegetation;the policy of“grazing prohibition,grazing rest,and rotational grazing”has allowed the restoration of vegetation;and afforestation is an effective way to promote the increase in FVC.
基金Supported by Internal Scientific Research Project of Shaanxi Provincial Land Engineering Construction Group Co.,Ltd.(DJNY2022-21)Shaanxi Provincial Youth Talent Promotion Program(NYKJ202228)+1 种基金Technology Innovation Center for Land Engineering and Human Settlements,Shaanxi Provincial Land Engineering Construction Group Co.,Ltd.and Xi an Jiaotong University(2021WHZ0094)Shaanxi Provincial Enterprise Innovation Striving for the First Young Talents Support Program Project(2021-1-2).
文摘[Objectives]The paper was to investigate the distribution characteristics of soil total nitrogen in low-efficiency forest land in the northern windy desert area of Jingbian County.[Methods]The distribution of soil total nitrogen in the 0-40 cm soil layer of 5 towns in the northern windy desert area of Jingbian County was studied through field sampling and laboratory detection.[Results]The average soil total nitrogen contents of Hongdunjie Town,Haizetan Town,Huanghaojie Town,Ningtiaoliang Town,Dongkeng Town and windy desert area in the 0-20 cm soil layer were 0.259,0.224,0.242,0.248,0.431 and 0.275 g/kg,respectively.The soil total nitrogen content in Dongkeng Town was higher than those in other towns,while there was little difference among other regions.The average total nitrogen contents in the 20-40 cm soil layer were 0.239,0.285,0.113,0.262,0.349 and 0.241 g/kg,respectively.The soil total nitrogen content in Huanghaojie Town was slightly lower than those in other towns,while that in Dongkeng town was higher.The variation coefficient of soil total nitrogen content in the survey area was greater than 30%,and there was great difference in spatial distribution.With the increase of soil depth,there was little change in soil total nitrogen content,namely the soil total nitrogen contents in 5 towns and windy desert area were not statistically different in the 0-40 cm soil layer.According to the nutrient grading standard of the second national soil survey,the soil total nitrogen content in the survey area was in the deficiency grade.[Conclusions]The research will provide a scientific guidance for the healthy and sustainable development of vegetation in arid regions.
基金supported by Major State Basic Research Development Program of China (973 Program, 2009CB421303)Youth Foundation Project+1 种基金National Natural Science Foundation of China (40901049)West Light Doctor Foundation of Chinese Academy of Sciences (O828881001)
文摘This experiment was conducted in three sites along a desertification gradient in Horqin Sandy Land, Northern China. Soils una-mended and amended with five types of plant residue in a wide range of C:N ratios from 9.9 to 82.2 were incubated for 70 days, during which C and N mineralization were measured. Along the desertification gradient from fixed sand dune to semifixed, and mobile sand dune: cumulative CO2-C produced from the unamended soils was 231.6, 193.3 and 61.9 μg/g, respectively, while net inorganic N was 22.9, 17.6 and 0.9 mg/kg. Soils amended with residues produced more CO2-C than the unamended soils across all sites. During the first 10 days, C mineralization rate of residue-amended soils decreased with the increase of C:N ratio at each site. However, the mineralization rates were poorly correlated with the C:N ratio in subsequent stage of incubation. Soils of mobile sand dune amended with higher C:N ratio (more than 32) residues produced less CO2-C than that of fixed and semifixed sand dune. NO3--N was the predominant form of inorganic N during the mineralization process in sandy soils. Carbon-to-nitrogen ratio (C:N) can be regarded as a predictor of the speed of N mineralization in sandy soil. The more C. microphylla residue with the lowest C:N ratio (9.9) added in soils, the more net inorganic N released. Our results suggest that C. microphylla residue when added to soil would potentially provide short-term plant available N and improve the soil quality in sandy land. The desertification process postponed the release of inorganic N from plant residues.
文摘Songnen Sandy Land lies in the eastern fringe of huge sandy belt of middle latitude inEurasia Continent Here is also the eastern fringe of desertification-prone land in China. Its specialconditions such as biology and climate, the history of evolution of sandy land and its location make itpossess features differing from other sandy lands in the country. This article systematitaly discussesthe regional featured such as the historical process, modern process, environmental factors ondesertification and the sandy land landscape and the degree of desertification, and raises some advicesfor rehabilitation and development in this area.
基金This research was supported by the National Key R&D Program of China(No.2020YFA0608404)a grant from the National Nature Science Foundation of China(41101006)and the Project of the Key Laboratory of Desert and Desertification,Chinese Academy of Sciences(KLDD-2019-008).
文摘Samples from the Horqin sandy land were exposed to a series of wind velocities,and sink particles were collected at the end of the diffusion section of a wind tunnel.Grain sizes of collected samples show great variation because of the granularity difference of the surface samples.The original samples show lower average content of SiO_(2) and higher average content of Al _(2)O_(3),Fe_(2)O_(3),MgO,CaO,Na_(2)O,and K_(2)O than collected samples.Compared with other dust source areas in China,the Horqin sandy land had higher content of Zr,Ba,SiO_(2),Al_(2)O_(3) and K_(2)O.Compared with the average upper continental crust(UCC)composition,surface samples were rich in the content of Y,Zr,Nb,Ba,La,Nd.Geochemistry characteristics of fine grain components of the Horqin sandy land differ from those from other dust source regions,because fine-grained particles in the Horqin sandy land were mostly derived from various local deposits formed in its unique depositional environments influenced by several tectonic activities.
基金supported by the Forestry Public Benefit Scientific Research Special Project of China(201504420)the National Science&Technology Pillar Program during the 12th Five-year Plan Period(2012BAD16B0102)
文摘Large areas of Artemisia ordosica Krasch., Caragana korshinskii Kom., and Caragana intermedia Kuang and H. C. Fu plantations were established on moving sand dunes in the Gonghe Basin (northeastern Tibetan Plateau) for vegetation restoration. Elevating our understanding of the changes in soil characteristics after the establishment of different plantation types can be useful in the context of combating deserdfication. To assess the effects of these plantation types on the restoration of sandy land, we measured soil physical-chemical properties at four depths (0-5, 5-10, 10-20, and 20-50 cm) in each of the three plantation types and also in non-vegetated moving sand dunes (as control sites). Generally, the establishment of A. ordosica, C korshinskii and C intermedia plantations on sand dunes has greatly ameliorated soil quality in the Gonghe Basin. Specifically, relative to the moving sand dunes, shrub plantation has increased the silt and clay contents, total porosity and water holding capacity, soil organic matter, total nitrogen, total phosphorus and total potassium contents. The calculated soil quality index suggested that in the Gonghe Basin, C. intermedia is the best choice for soil amelioration. In all the three plantation types, soil amelioration mainly occurred in the shallow depths.
基金jointly funded by the National Natural Science Foundation of China(GrantNo40775019)Desert Meteorology Science Foundation of China(Grant NoSqj2009012)Project of Key Laboratory of Oasis Ecology(Xinjiang University)Ministry of Education(Grant NoXJDX0206-2009-08)
文摘Improving and validating land surface models based on integrated observations in deserts is one of the challenges in land modeling. Particularly, key parameters and parameterization schemes in desert regions need to be evaluated in-situ to improve the models. In this study, we calibrated the land-surface key parameters and evaluated several formulations or schemes for thermal roughness length (z 0h ) in the common land model (CoLM). Our parameter calibration and scheme evaluation were based on the observed data during a torrid summer (29 July to 11 September 2009) over the Taklimakan Desert hinterland. First, the importance of the key parameters in the experiment was evaluated based on their physics principles and the significance of these key parameters were further validated using sensitivity test. Second, difference schemes (or physics-based formulas) of z 0h were adopted to simulate the variations of energy-related variables (e.g., sensible heat flux and surface skin temperature) and the simulated variations were then compared with the observed data. Third, the z 0h scheme that performed best (i.e., Y07) was then selected to replace the defaulted one (i.e., Z98); the revised scheme and the superiority of Y07 over Z98 was further demonstrated by comparing the simulated results with the observed data. Admittedly, the revised model did a relatively poor job of simulating the diurnal variations of surface soil heat flux, and nighttime soil temperature was also underestimated, calling for further improvement of the model for desert regions.
基金financially supported by the National Natural Science Foundation of China (41171414)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-EW-QN313)+1 种基金the Chinese Academy of Sciences Visiting Professorships for Senior International Scientists (2011T2Z36)the Key Project of Scientific and Technical Supporting Programs (2011BAC07B02-09), and the National Basic Research Program of China (2009CB421303)
文摘Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however the information on how dune stabilization influences the spatial scale dependence of plant diversity is still lacking. In this study, we measured the plant species richness, soil properties and altitude across four spatial scales (1, 10, 100 and 1,000 m2) at three different dune stabilization stages (mobile dune, semi-fixed dune and fixed dune) in Horqin Sandy Land, Northern China. We also examined the relationships between plant species richness, community composition and environmental factors along the gradient of dune stabilization. Our results showed that plant species richness increased with the increase of spatial scales in each dune stabilization stage, as well as with the increase of dune stabilization degrees. Canonical correspondence analysis (CCA) showed that plant distribu- tions in the processes of dune stabilization were determined by the combined environmental gradient in relation to soil organic carbon (SOC), total nitrogen (TN), carbon/nitrogen (C/N), pH, electrical conductivity (EC), soil water content (SWC), fine sand (FS), very fine sand (VFS), silt and clay (SC), and altitude. Plant species richness was significantly and positively correlated to SOC and TN in mobile dune, and significantly and positively correlated to SOC, TN, C/N, VFS and SC in semi-fixed dune. However, no significant correlation between plant species richness and environmental factors was observed in fixed dune. In addition, plant species richness in different dune stabili- zation stages was also determined by the combined gradient of soil properties and altitude. These results suggest that plant species richness has obvious scale dependence along the gradient of dune stabilization. Soil resources depending on dune habitats and environmental gradients caused by dune stabilization are important factors to de- termine the scale dependence of species diversity in sand dune ecosystems.
基金funded by the National Nonprofit Institute Research Grant of Chinese Academy of Forestry(CAFYBB2011003,CAFYBB2011002)the Key Laboratory of Agrometeorological Support and Applied Technique of China Meteorological Administration(AMF201107,AMF201204)the National Natural Science Foundation of China(40801173)
文摘Remote sensing is a valuable and effective tool for monitoring and estimating aboveground biomass (AGB) in large areas.The current international research on biomass estimation by remote sensing technique mainly focused on forests,grasslands and crops,with relatively few applications for desert ecosystems.In this paper,Landsat Thematic Mapper (TM)/Enhanced Thematic Mapper Plus (ETM+) images from 1988 to 2007 and the data of 283 AGB samples in August 2007 were used to estimate the AGB for Mu Us Sandy Land over the past 30 years.Moreover,temporal and spatial distribution characteristics of AGB and influencing factors of climate and underlying surface were also studied.Results show that:(1) Differences of correlations exist in the fitted equations between AGB and different vegetation indices in desert areas.The modified soil adjusted vegetation index (MSAVI) and soil adjusted vegetation index (SAVI) show relatively higher correlations with AGB,while the correlation between normalized difference vegetation index (NDVI) and AGB is relatively lower.Error testing shows that the AGB-MSAVI model established can be used to accurately estimate AGB of Mu Us Sandy Land in August.(2) AGB in Mu Us Sandy Land shows the fluctuant characteristics over the past 30 years,which decreased from the 1980s to the 1990s,and increased from the 1990s to 2007.AGB in 2007 had the highest value,with a total AGB of 3.352×106 t.Moreover,in the 1990s,AGB had the lowest value with a total AGB of 2.328×106 t.(3) AGB with relatively higher values was mainly located in the middle and southern parts of Mu Us Sandy Land in the 1980s.AGB was low in the whole area in the1990s,and relatively higher AGB values were mainly located in the southern parts of Uxin.In 2007,AGB in the whole area was relatively higher than those of the last twenty years,and higher AGB values were mainly located in the northern,western and middle parts of Mu Us Sandy Land.
基金funded by the National Basic Research Program of China(2013CB956000,2012CB426501)
文摘Aeolian deposits from the deserts in northern China have been used for palaeoenvironmental research to understand aeolian sedimentology and its dynamic connection to past climate conditions. The Tengger Desert in China is sensitive to the waxing and waning of the monsoonal system. In response to past climate change, the southern margin of the Tengger Desert has evolved significantly since the last glacial period. However, previous attempts to date aeolian deposits in this region were mainly based on radiocarbon dating, which has problems when applied to aeolian deposits. Moreover, sedimentary records are limited. Accordingly, past aeolian activity in this desert remains poorly understood. In the present study, we dated sand samples from Gulang county at the southern margin of the Tengger Desert using optically stimulated luminescence (OSL) to understand the history of aeolian activity in this region. Our samples represented well-sorted aeolian sands and sandy loess. Aeolian sands are evidence of dune field buildup and sparse vegetation cover whereas sandy loess is evidence of improved stabilization of sand dunes resulting from ameliorated vegetation cover. Certain samples showed a decline in the equivalent dose (D<sub> e </sub>) values when successive integration intervals were applied, which resulted from unstable OSL signals from non-fast components in the initial part of the decay curve. In order to obtain reliable D<sub> e </sub> estimates, we investigated component-resolved and different background subtraction approaches, and compared the resultant D<sub> e </sub> estimates. We adopted the early background subtraction method to derive D<sub> e </sub> values. Luminescence chronologies and sedimentary records indicated that sand dunes accumulation occurred before 10 ka, and sandy loess developed between 9.5 and 7.6 ka when sand dunes were stabilized as a result of increased effective moisture levels. The transition between sand dune mobilization and stabilization emphasizes the significance of an effective moisture threshold in controlling aeolian activity. Mobilization of sand dunes at ~2.3 ka might be related to an increased aridity during the Late Holocene.
基金Funding was provided by the National Key Technology R&DP rogram (2012BAD16B01)the Special Research Program for Public-welfare Forestry of China (201104077)the National Natural Science Foundation of China (31170667)
文摘This study investigated the distribution pattern of biological soil crust (BSC) in Artemisia ordosica communities in Mu Us Sandy Land. Three experimental sites were selected according to grazing pressure gradient. In each experimental site, the total vegetation cover, A. ordosica cover, BSC cover, litter-fall cover, BSC degree of fragmentation, BSC thickness and soil properties were investigated in both fixed and semi-fixed sand dunes and simultaneously analyzed in the laboratory. The results showed that at the same grazing pressure, BSC cover and composition were significantly affected by the fixation degree of sand dunes. In addition, BSC cover in the fixed sand dunes was 83.74% on average, whereas it is proportionally dominated by 28% mosses, 21% lichens, and 51% algae. Meanwhile, BSC cover in the semi-fixed sand dunes was 23.54% on average, which is proportionally domi- nated by 6.3% mosses, 2.5% lichens, and 91.2% algae. Fine sand, organic matter, and total nitrogen (N) contents in the fixed sand dunes were all significantly higher than those in the semi-fixed sand dunes. Litter-fall cover de- creased along the grazing pressure gradient, whereas BSC fragmentation degree increased. Fine sand content decreased along with the increase of grazing pressure, whereas medium sand content increased in both fixed and semi-fixed dunes. The organic matter and total N contents in the no grazing site were significantly higher than those in light and normal grazing sites. However, there were no significant differences between the light and normal grazing sites. In addition, there were also no significant differences in BSC thickness between the light and normal grazing sites in the fixed sand dunes. However, a significant decrease was observed in both BSC cover and thick- ness in the normal grazing site. The BSC in the semi-fixed dunes was more sensitive to disturbance.
基金supported by the National Natural Science Foundation of China(Grant No.41661006)the Fundamental Research Funds for the Central Non-Profit Research Institution of Chinese Academy of Forestry(Grant No.CAFYBB2014QB046)Chinese Scholarship Council
文摘Soil water is the main form of water in desert areas, and its primary source is precipitation, which has a vital impact on the changes in soil moisture and plays an important role in deep soil water recharge(DSWR) in sandy areas. This study investigated the soil water response of mobile sand dunes to precipitation in a semi-arid sandy area of China. Precipitation and soil moisture sensors were used to simultaneously monitor the precipitation and the soil water content(SWC) dynamics of the upper 200-cm soil layer of mobile sand dunes located at the northeastern edge of the Mu Us Sandy Land of China in 2013. The data were used to analyze the characteristics of SWC, infiltration, and eventually DSWR. The results show that the accumulated precipitation(494 mm) from April 1 to November 1 of 2013 significantly influenced SWC at soil depths of 0-200 cm. When SWC in the upper 200-cm soil layer was relatively low(6.49%), the wetting front associated with53.8 mm of accumulated precipitation could reach the 200-cm deep soil layer. When the SWC of the upper 200-cm soil layer was relatively high(10.22%), the wetting front associated with the 24.2 mm of accumulated precipitation could reach the upper 200-cm deep soil layer. Of the accumulated 494-mm precipitation in 2013, 103.2 mm of precipitation eventually became DSWR, accounting for 20.9% of the precipitation of that year. The annual soil moisture increase was 54.26 mm in 2013. Accurate calculation of DSWR will have important theoretical and practical significance for desert water resources assessment and ecological construction.
基金funded by the National Basic Research Program of China (2013CB429903)the National Natural Science Foundation of China (41201248, 31170496)
文摘Shrub presence has an important effect on the structuring of ground beetles in desert ecosystems. In this study, in order to determine how shrubs and different species influence ground beetle assemblages in a sandy desert scrubland dominated by two different shrub species, namely Calligonum mongolicum and Nitraria sphaerocarpa, we sampled the ground beetles using pitfall traps during spring, summer and autumn in 2012. At the community level, the activity density of the ground beetles was shown to be significantly higher under shrubs than in intershrub bare habitats in spring; but an opposite pattern occurred in autumn, suggesting the presence of sea- son-specific shrub effects on the activity density of the ground beetles. Meanwhile, at the trophic group level, the activity density and species richness of predators were significantly greater under shrubs than in intershrub bare habitats in spring, whereas an opposite trend occurred on the activity density in autumn. N. sphaerocarpa shrubs had a positive effect on the activity density of herbivores in the three seasons, and C. mongolicum shrubs had a positive effect on the activity density of detritivores in spring and autumn. At the species level, more Microdera sp. was captured under shrubs than in intershrub bare habitats in spring. During the same time, we also found that C. mongolicum shrubs had a positive effect on Blaps gobiensis in spring, Carabus sp. in autumn, and Tentyria sp. in spring and autumn, and N. sphaerocarpa shrubs had a positive effect on Cyphogenia chinensis, Sternoplax setosa in spring and summer, and Curculionidae sp. 1 in summer and autumn. The study results suggest that shrub presence, shrub species and season variation are important factors for ground beetle assemblages in this desert ecosystem, but the responses of beetles differed among trophic and taxonomic levels.
基金supported by the National Basic Research Program of China (973 Program) (2009CB421303)the National Natural Science Foundation of China (40801036) from the Cold and Arid Regions of Environmental and Engineering Research Institute,Chinese Academy of Sciences