Ground-active arthropod responses to rainfall-induced dune microhabitats in a desertified steppe ecosystem,China

Different microhabitats along dune slope were found to affect the distribution of plant performances and soil properties in desertified ecosystems. However, the ground-active arthropod responses to rainfall-induced dune microhabitats were largely unknown in desertified regions. At dune top, midslope and bottom, ground-active arthropods were sampled by the method of pitfall traps in addition to the herbaceous and soil measurements during spring, summer and autumn from 2012 to 2013. Ground-active arthropod had a strong dynamics in time, seasonally and yearly in responses to rainfall-induced dune microhabitats and the variations were significant higher than those of soil and herbaceous properties. The abundance distribution of dominant taxa （i.e. Melolonthidae, Carabidae, Glaphyridae, Tenebrionidae and Formicidae families） among dune microhabitats was similar between seasons within the same year, whereas they differed markedly between two sampling years with varying rainfall patterns. A significant （P〈0.05） difference in total abundance, taxa richness and Shannon index among dune microhabitats was found only in certain season time, particularly in 2013; however, no significant （P〉0.05） differences were found among dune microhabitats when averaged on three sampling seasons within the year of either 2012 or 2013. In all, the taxonomical structure differed considerably from the community structure in ground-active arthropod response to rainfall-induced dune microhabitats. The spatial distribution of taxonomical groups among dune microhabitats was significantly affected by inter-annual rainfall changes, whereas that of community structure was affected by both intra- and inter-annual rainfall changes in desertified ecosystems.

THE POSSIBILITIES AND REALITIES ON THE REMANAGEMENT OF DESERTIFIED LANDS IN THE TRANSITIONAL ZONE BETWEEN THE DRY-FARMING AREA AND THE GRAZING AREA IN NORTH CHINA

The desertification process is rapidly developing at present and 61.5% of the land area in the zone are already desertified.Among the desertified lands, 26.9% are seriously desertified, 25% most seriously desertified and 47.4% are the lands where desertification is under way. They are caused by over-reclamation for farming, over-grazing, unreasonable collection of firewood,the destruction of vegetation and the misuse of water resources. Under the ecological environment in semi-arid zone,the degraded environment process possesses the ability of restoring to its original status as soon as the interruption of excessive human activities are eliminated. The fencing- and-self-cultivating method is an effective measure adopted universally in semi-arid zone to cure the desertified lands.The desertified lands can be readjusted and controlled easily if other controlling measures are supplemented. The fundamental ways to control desertification are to utilize rationally the resources, to readjust the existing

New Utilization Model of Karst Rocky Desertified Land in Southwest China:Ecological Planting of Dendrobium officinale Kimura et Migo on Bare Rocky Mountains

The Yunnan-Guangxi-Guizhou rocky desertified area in southwestern China is one of the contiguous extremely poor areas identified in the Outline of Poverty Alleviation and Development in the Rural Areas of China(2011-2020).In rocky desertified areas,due to long-term severe soil erosion,large areas of bedrock are exposed or gravels are accumulated.This bare rock and gravel-mulched land has become the main land type in the rocky mountains.Under normal circumstances,it cannot be directly used for agriculture,forestry,animal husbandry,and fishery production,and is classified as land that is difficult to be utilized.In recent years,in Debao County,Baise City,Guangxi Zhuang Autonomous Region,as a deeply impoverished county in the Yunnan-Guangxi-Guizhou rocky desertified area,a new land use model of karst rocky desertified land,that is,planting Dendrobium officinale Kimura et Migo on bare rocky ground,has emerged,and certain poverty alleviation benefits have been achieved initially.In this article,on the basis of analyzing the suitability of planting D.officinale Kimura et Migo on karst rocky desertified land,the practice of planning D.officinale Kimura et Migo on the rocky desertified land in Debao County was elucidated,and then suggestions for reasonable promotion of ecological planting of D.officinale Kimura et Migo in karst rocky desertified areas were put forward.

Dynamic change of desertified land in each county around Qinghai Lake in recent 30 years

Desertification is one of the most serious eco-environmental problems around Qinghai Lake.Based on GIS and RS,GIS analysis was used to obtain the information of spatial-temporal change and different pattern of desertification in each county around Qinghai Lake in four phases of1976,1987,1995 and 2006.Using the function of intersect and overlay supported by ARCGIS,with analyzing attributes of vector RS images,we obtained transition data and established transfer matrix of land-use types in recent 30 years,besides,protracted land-use transition maps of all desertification classes.In further,we analyzed transition quantity and direction of desertification in each county,moreover,reconstructed the process of spatial-temporal evolution of desertification.The results are showed below:(1)it's the transition between desertified land and others but not in the desertified that played the main role in Gangcha and Gonghe County,while the transfer between desertified lands were greater than that with other land-use types in Haiyan County.(2)Extremely severe desertified land mainly distributes in Ketu and Sand Islands that belongs to Haiyan County,and moderate desertified land in riversides of Gangcha County,also,the light desertification expanded too rapidly to become the most desertified land-use type in the surrounding of Qinghai Lake since 1976.(3)By using relative change rate of desertified land,the regional variability rank from top to toe was Gangcha,Haiyan and Gonghe.

Biological Characteristics of Carex brunnescens for Sand Fixation in the Source Region of the Yellow River

Carex brunnescens, a pioneer plant that has an excellent ability to fix sand in the source region of the Yellow River （Maqu）, plays an important role in maintaining the ecosystem stability of alpine grassland in Maqu. In this study, the biological characteristics （phonological characters, the growth process of overground and underground organs, and the morphological characters of underground organs） of C. brunnescens were studied by a field observation experiment. The results showed that C. brunnescens had the characteristics of turning green earlier than other plants, a long growth period, and two flowering and fruiting cycles. The leaf width, length and number of a single plant, and the density, coverage and leaf density of community increased significantly from the leaf extension period to the fruit mature period and then tended to be stable in the withering period, while the plant height and leaf area of a single plant and the leaf area of community rose significantly at first and then decreased. Underground stems （horizontal and vertical stems） and roots of C. brunnescens could survive in sand at a depth of 0-60 cm. The number of middle roots （0.2-0.5 mm in diameter） was the largest in all soil layers （0-20, 20-40 and 40-60 cm）, and the total length of fine roots （〈0.2 mm） were the maximum in the sand at a depth of 20-40 cm, while the total length of middle roots was the maximum in the sand layer at a depth of 0-20 cm. The length, fresh weight and dry weight of the main root, horizontal and vertical stems was the maximum in the sand layer at a depth of 10-30 cm and was the minimum in the sand layer at a depth of 40-50 cm. It is concluded that C. brunnescens can well adapt to the alpine sand habitat of Maqu, can be used as the constructive species for ecological restoration in the alpine desertified grassland of Maqu, and has good popularization and application prospects.

Features on N/P ratio of plants with different functional groups between two types of steppe in semi-arid area

The differences in nitrogen/phosphorus(N/P)ratios of different functional groups in ecology are more helpful in explaining species competition and community dynamics.Based on the functional groups of plant growth type,carbon metabolism pathway,root type and phylogenetic type,we analyzed characteristics of leaf N/P ratios of 77 species in Sanggendalai(typical grassland zone)of Zhenglan Banner,Inner Mongolia,China and 91 species in the Habahu National Nature Reserve(desertified grassland zone)in Yanchi County of Ningxia,China.The results show that the N/P ratio(16.91)of C3 plants in the desertified steppe was significantly larger than that(12.72)in the typical steppe,but there was no significant difference between the N/P ratios of C4 plants in the two zones.There was no significant difference in N/P ratios between C3 plants and C4 plants in the same zone.Similarly,the N/P ratio(16.60)of dicotyledons in desertified steppe were significantly higher than that(12.98)in typical steppe,while differences in N/P ratios between monocotyledonous plants of the two zones was not significant,and there existed no significant difference in N/P ratios between dicotyledonous and monocotyledonous plants in the same zone.The N/P ratio had significant difference between gramineous and non-gramineous plants in the typical steppe but not in the desertified steppe,but there existed no significant difference in N/P ratios among different root types of perennial herbaceous plants in the same type of steppe or between two types of steppe.Thus,different features on the N/P ratios of C3 plants and dicotyledonous plants between typical steppe and desertified steppe may lead to different growth status of plants,and the N/P ratio stoichiometric of the same plant functional group may be a foundation of the changes of a plant community.

Vegetation actualities and feasibility of restoration for the periphery of oasis in extreme arid region: taking Qira County of Xinjiang as an example

The periphery of oasis plays an important role in mutual transformation between desert and oasis. Vegetation is an important part in the ecosystem and it is an important index indicating certain landscape, Based on several times field investigation, this paper attaches importance to the feasible measures for vegetation restoration according to the current condition of study area - Qira County of Xinjiang Uygur Autonomous Region, In order to improve die local ecological environment, people lived in Qira County should work bard to protect their homehind and reduce the degree of sandstorm, More protection forest should be established along with other ecological techniques. Results derived from this study contribute largely to the ecological environmental protection of oasis.

Study of spatial distribution of sandy desertification in North China in recent 10 years

Sandy desertification is a land degradation characterized by wind erosion, mainly resulted from the excessive human activities in arid, semiarid and part of sub-humid regions in North China. It is one of main kinds of desertification/land degradation as well as water-soil erosion and salinization in China. Rapid and continuous spread of sandy desertification during last 50 years has created a major environmental and socio-economic problem in North China. Remote sensing monitored results in 2000 showed that the sandy desertified land area has been 38.57× 104 km2. The area of potential to slightly sandy desertified land is 13.93× 104 km2, moderately land 9.977×104 km2, severely land 7.909 ×104 km2 and very severely land 6.756×104 km2. Sandy desertification mainly occurs in the semi-arid mixed farming-grazing zone and its northern rangeland zone, semi-arid dryland rainfed cropping zone and arid oasis-desert margin zone. The average annually developmental rate of sandy desertified land increased from 2,100 km2 ·a-1 in 1976-1988 to 3,600 km2 · a-1 in 1988-2000. The basic status of sandy desertification in North China is 'overall deterioration, while local rehabilitation'. Already achieved rehabilitation results and monitoring assessment show that about 60% of desertified land in North China can be restored under the conditions of rational land-use ways and intensity.

Determination of the Status of Desertification in the Capital of Mauritania and Development of A Strategy for Combating It

Mauritania, located in the Western Sahara, is one of the least developed countries in the Sahara Desert. Its capital, Nouakchott, which is home to 23% of its population, suffers from soil erosion from the Sahara and saltwater intrusion from the Atlantic Ocean. The local environment is under pressure from the combined effects of climate and socio-economic factors, with desertification being recognized as the greatest threat to life. In this context, high-resolution remote sensing images of Nouakchott obtained during the winters of 1985, 1988, 2000, 2006, and 2010 are selected for interpretation and classification. Analysis of the types of desertification and land use reveals the temporal and spatial characteristics of five distinct time periods from 1985 to 2010. This study analyzes the current status of desertification in Nouakchott and suggests five preventive measures.

Sandy desertification in the north of China

With the economic and social development, desertification exerted increasingly pro-found influences on natural environment and social development and attracted widespread atten-tion of international communities, China, as one of the countries facing severe desertificationproblems, has witnessed some progress in understanding and combating the process of desertifi-cation through many years of hard work. Based on the experiences and research achievements,this paper briefly discusses the causes, developmental processes, damage assessment and con-trol mechanism of desertification in the north of China so as to provide some basic experiences forthe further study of desertification.