Increased pollinator service and reduced pollen limitation in the fixed dune populations of a desert shrub.

Evaluations of restoration success usually focus on the structural aspects of ecosystems. Pollination, as an important functional aspect, is often overlooked. Here, the shifts in pollinator assemblage and pollen limitation in the desert shrub Caragana microphylla were examined along a restoration gradient in Horqin Sand Land, northern China.

Earlier flowering did not alter pollen limitation in an early flowering shrub under short-term experimental warming.

In animal pollinated plants, phenological shifts caused by climate change may have important ecological consequences. However, no empirical evidence exists at present on the consequences that flowering phenology shifts have on the strength of pollen limitation under experimental warming. Here, we investigated the effects of experimental warming on flowering phenology, flower density, reproductive success, and pollen limitation intensity in Caragana microphylla and evaluated whether earlier flowering phenology affected plant reproduction and the level of pollen limitation using warmed and unwarmed open top chambers in the Horqin Sandy Land of Inner Mongolia, northern China.

Effects of sand burial on the survival and growth of two shrubs dominant in different habitats of northern China.

Plants that grow in dune ecosystems always suffer from sand burial. Shrubs play implications on the healthy functioning of dune ecosystems due to control blowing sand. However, the survival and growth responses of shrubs to sand burial remain poorly understood.

[Physiological response of corn seedlings to changes of wind-sand flow strength].

Corn seedlings are often harmed by strong wind-sand in the spring in semi-arid wind-sand area of west of Northeast China. In order to understand physiological response mechanisms of the corn seedlings to wind-sand damage, the changes in MDA content, membrane permeability, protective enzymes activities and osmotic regulation substances at 0 (CK) , 6, 9, 12, 15 and 18 m . s-1 wind speed (wind-sand flow strength: 0, 1.

[Effects of sand burial on growth and physiological process of Agriophyllum squarrosum seedlings in Horqin Sand Land of Inner Mongolia, North China].

In 2010-2011, a sand burial experiment was conducted on the Horqin Sand Land of Inner Mongolia to study the growth characteristics and physiological properties of Agriophyllum squarrosum seedlings under different depths of sand burial. The A. squarrosum seedlings had stronger tolerance against sand burial.

Biophysical properties as determinants for soil organic carbon and total nitrogen in grassland salinization.

Grassland salinization causes considerable changes to soil and vegetation, which can lead to changes in soil organic carbon (C) and total nitrogen (N). These changes have complex causal relationships. A significant correlation between soil organic C and total N and any soil or vegetation property does not necessarily imply a significant direct effect of the property on soil organic C and total N.

[Effects of different afforestation types on soil faunal diversity in Horqin Sand Land].

In order to deeply understand the effects of afforestation on the soil faunal diversity in mobile sand land, an investigation was conducted on the community structure of soil animals in the mobile sand land and its adjacent about 30 years old forest land and shrub land in Hrqin Sand Land. Afforestation on the mobile sand land had remarkable effects on the soil properties, especially the soil environment in shrub land, in which, the soil water content, pH, and nutrient contents were improved. In the three lands investigated, a total of 485 individuals belonging to 11 soil animal groups were collected, among which, Acarina and Collembola were the dominant groups, Corrodentia was the common group, and the others were of rare groups.

[Community structure and diversity of soil arthropods in naturally restored sandy grasslands after grazing].

Taking the Naiman Desertification Research Station under Chinese Academy of Sciences as a base, an investigation was conducted on the community structure of soil arthropods in the naturally restored sandy grasslands after different intensity grazing disturbance, with the effects of vegetation and soil on this community structure approached. In the non-grazing grassland, soil arthropods were rich in species and more in individuals, and had the highest diversity. In the restored grassland after light grazing, soil arthropods had the lowest evenness and diversity.

[Effects of vegetation cover on physical and chemical properties of bio-crust and under-layer soil in Horqin Sand Land].

To understand the effects of different vegetation cover on the bio-crust and its under-layer soil in Horqin Sand Land, the bio-crust and 0-5 cm soil samples in Artemisia frigida, Salix microstachya, Populus simonii, and Pinus sylvestris var. mongolica stands were collected, and their physical and chemical properties were studied. After fifteen years enclosure protection and vegetation establishment, the flowing sand dune in most natural and artificial vegetation sites was covered with bio-crusts.

[Spatial heterogeneity of soil organic carbon and total nitrogen of sandy grassland in the restoration of degraded vegetation in Horqin Sandy Land, northern China].

Based on the field investigation and lab analysis, we used geostatistics method to examine the spatial heterogeneity of soil organic carbon and total nitrogen in a 0-year fenced mobile dune (MD11), an 11-year fenced mobile dune (MD11) and a 20-year fenced mobile dune (MD20) in Horqin Sandy Land. The results showed that the average values of vegetation cover, species number and diversity, soil organic carbon and total nitrogen (0-20 cm) contents increased with the increase in fenced age of mobile dunes. Geostatistical analysis showed that the proportions of relative structural variance C/(C0 + C) of soil organic carbon and total nitrogen in each dune were over 65% , which suggested that they had obvious spatial autocorrelation.

[Distribution of Formica cunicularia mound and related affecting factors on mobile dune in Horqin sandy land].

Taking the typical mobile dune in Horqin sandy land as test object, the density, diameter, and coverage of Formica cunicularia mounds on different land forms were investigated by quadrate method, with the spatial distribution of F. cunicularia mounds and the effects of topography and soil property on F. cunicularia nest-building activities discussed.

[Crust development and subsurface soil properties under dominant shrubs in the process of dune restoration, Horqin Sand Land].

Soil crust is a common and widespread phenomenon in desert areas all over the world due to its extraordinary ability to survive desiccation and extreme temperatures, high pH and salinity. Despite its unassuming appearance, biological soil crusts play a significant role in desert ecosystems, including involvement in the process of formation, stability and fertility of soil, preventing soil erosion by water or wind, increasing the possibility of vascular plant colonization, and being responsible for the stabilization of sand dunes. This study taking Horqin Sand Land as research region, by field sampling, crust and topsoil (0-2.

[Effects of desertification on C and N storages in grassland ecosystem on Horqin sandy land].

Sandy grassland is widespread in northern China, where desertification is very common because of overgrazing and estrepement. However, little is known about the effects of desertification on grassland C and N storages in this region. A field survey was conducted on Horqin sandy grassland, and desertification gradients were established to evaluate the effects of desertification on C and N storages in soil, plant, and litter.

[Characteristics of Caragana microphylla sap flow and water consumption under different weather conditions on Horqin sandy land of northeast China].

Employing heat balance Dynamax packaged sap flow measuring system and automatic weather recording system, the sap flow of artificial Caragana microphylla community on Horqin sandy land of northeast China was monitored consecutively in 2006, and the photosynthetically effective radiation, air temperature, relative humidity and wind velocity were measured synchronously. According to the manual records of weather conditions, four most representative weather conditions were gathered up to analyze the relationships of C. microphylla sap flow and its single branch water consumption with test meteorological factors.

[Changes of species diversity and productivity in relation to soil properties in sandy grassland in Horqin Sand Land].

This study provided the analysis of changes of species diversity and productivity in relation to soil properties in six typical habitats (wet meadow, dry grassland, fixed dune, semi-fixed dune, semi- shifted dune, and shifted dune) in Horqin Sand Land. The changes of vegetation and soil properties, following the degraded process of sandy grassland, show the following trends: (1) productivity decreases gradually, (2) species diversity changes in a pattern of near-formal distribution, firstly increases from wet meadow, dry grassland, to fixed dune (at the peak), and then decreases from semi-fixed dune, semi-shifted dune, to shifted dune, while (3) contents of soil fine sand, silt, soil organic carbon, total nitrogen, and electrical conductivity, decrease consistently. Ordination technique of canonical correspondence analysis (CCA) was used to examine the relationship between the vegetation pattern and soil parameters.

[Research progress on wind erosion control].

Wind erosion is the main inducement and an important process of desertification, and also, a main environmental problem needed to be controlled in many countries and areas. Based on the formation mechanisms of wind erosion and some important research results, this paper reviewed the biological, chemical, and mechanical measures in wind erosion control, which could be applied individually or integrated together to decrease or prevent wind erosion. It was suggested that management should be strengthened to ensure a better effect in applying these measures to further improve ecological environment.

[Dynamics of carbon and nitrogen storages in plant-soil system during desertification process in Horqin sandy land].

Organic carbon and nitrogen storages in plant-soil system were measured at different desertification stages (potential, light, moderate, severe, and most-severe) in Horqin sandy land. From potential desertification to light, moderate, severe, and most-severe desertification, total biomass (aboveground and belowground) carbon storages decrease by 26.4%, 51.

[Fractal features of soil particle size distribution in degraded sandy grassland during reclamation and enclosure].

Based on the analysis of 42 soil samples from the grassland reclaimed and enclosed different years, this paper studied the fractal features of soil particle size distribution and the relationships between fractal features and soil properties. The results showed that the fractal dimension of soil particle size distribution in 0 approximately 30 cm soil layer ranged from 2.378 in reclaimed land to 2.

[Effect of grazing on sandy grassland ecosystem in Inner Mongolia].

This experiment was carried out for 5 years in Horqin sandy land, lnner Mongolia, which had 4 treatments: Non-grazing (NG), light grazing (LG), moderate grazing (MG) and over grazing (OG). The results showed that different grazing intensities resulted in different development trend of the pasture ecosystem, of which, the injury of OG on pasture ecosystem was very great. The plant diversity, vegetation coverage, plant height and primary productivity under continuous overgrazing for 5 year were 87.

[Effects of land use and management on soil quality of Heerqin sandy land].

The changes of soil physical, chemical and biological properties under different land use and management lasted for 14 years were investigated on the Heerqin sandy land. The results showed that among various land use systems marked differences exhibited in soil quality indicators, including soil particle composition, porosity distribution, bulk density, water-holding capacity, organic matter and nutrient contents, pH, and enzyme activities. Most of these soil quality indicators were the highest in the orchard intercropped with crops and perennial grass (agroforestry systems), intermediate in the well-management irrigated farmland, and the lowest in the less-management dry farmland.

[Influences of grazing and exclosure on carbon sequestration in degraded sandy grassland, Inner Mongolia, north China].

Very little is known about the effects of continuous grazing and exclosure on carbon sequestration in semi-arid sandy grassland of North China. Soil-plant system carbon in representative degraded sandy grassland in Horqin sandy steppe (N42 degrees 58', E 120 degrees 42') was measured. Three situations were compared: continuous grazing (CG), exclosure for 5 years (5EX) and exclosure for 10 years (10EX).

[Influence of saltwater irrigation on the yield and quality of Cynodon dactylon under desert conditions].

Responses of six varieties (Suwannee, Coast cross, Tifton44, Tifton68, Tifton78 and Tifton85) of Cynodon dactylon to irrigation-water salinity were investigated in field by means of a double line source experimental design. The digestibility of the grass by goat was analyzed using the rumen gastric justice digestion method. The results showed that the six varieties grew well, and had a high yield of fresh grass when eletro-conductivity (Eci) < 10 ds.

[Influencing mechanism of several shrubs and subshrubs on soil fertility in Keerqin sandy land].

Keerqin sandy land is one of serious desertification areas in the semiarid zone of north China, and shrubs are the dominant plant life form and play an important role in the region. The effects of "fertile island" and rhizosphere of several shrubs and subshrubs were studied. The results showed that the concentrations of organic C, total N and total P, and values of electrical conductivity (EC) in the soils under the canopy of shrubs increased by 56%, 51%, 37%, and 51%, respectively, compared with those of the soils in open spaces, but there was no significant difference in pH value between the soils under shrub canopies and in open spaces.