Effects of fencing on vegetation and soil restoration in a degraded alkaline grassland in northeast China

In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent（DSE）/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application.

Soil restoration research advances of artificial sand-binding vegetation ecosystem in the Tengger Desert, Northern China

Soil plays an important role in desert ecosystem, and is vital in constructing a steady desert ecosystem. The management and restoration of desertified land have been the focus of much discussion. The soil in Shapotou desert region has developed remarkably since artificial sand-binding vegetation established in 1946. The longer the period of dune stabilization, the greater the thickness of microbiotic crusts and subsoil. Meanwhile, proportion of silt and clay increased significantly, and soil bulk density declinced. The content of soil organic matter, N, P, and K similarly increased. Therefore, soil has developed from aeolian sand soil to Calcic-Orthic aridisols. This paper discusses the effects brought about by dust, microbiotic soil crust and soil microbes on soil-forming process. Then, we analyzed the relation between soil formation and sand-binding vegetation evolution, in order to provide a baseline for both research on desert ecosystem recovery and ecological environment governance in arid and semi-arid areas.

Evaluation of Combined Landscape Restoration Practices on Soil Organic Carbon Stocks in Semiarid Regions of Burkina Faso

Forest and landscape restoration (FLR) practices have been reported to improve soil organic carbon stocks (SOCs) and contributing to climate change mitigation. This study aims to evaluate the impact of combined FLR practices, mainly developed in semiarid regions, on SOCs. The SOCs, soil texture, bulk density (ρ), pH, CO2 emissions, and herbaceous biomass were determined at a 0 - 30 cm depth. The experimental design comprised degraded land without FLR practices and three sets of combined FLR practices. These practices included “zaï” + stone bunds + organic manure + assisted natural regeneration (ANR) used to convert degraded land into forest (GF) and cropland (PARL);“zaï” + stone bunds + crop rotation + crop/fallow successions + ANR used to convert degraded land into cropland (OARL) and “zaï”+ stone bunds + organic manure used to convert degraded land into cropland (KARL). SOCs were highest (20.02 t C ha−1) under OARL compared with the other combinations of FLR practices. SOCs increased by 99% (+0.2 t C ha−1⋅yr−1), 58% (+0.3 t C ha−1⋅yr−1) and 13% (+0.2 t C ha−1⋅yr−1) under GF, OARL and KARL, respectively, and decreased by 15% (−0.1 t C ha−1⋅yr−1) under PARL. This study provides additional information explaining SOC variation in restored degraded land through the implementation of a combination of FLR practices. This is useful for recommending the combination “zaï” + stone bunds + crop rotation + crop/fallow successions + ANR to improve SOCs in the semiarid agroecosystem.

Accumulation of soil organic carbon during natural restoration of desertified grassland in China's Horqin Sandy Land

China＇s Horqin Sandy Land,a formerly lush grassland,has experienced extensive desertification that caused considerable carbon（C） losses from the plant-soil system.Natural restoration through grazing exclusion is a widely suggested option to sequester C and to restore degraded land.In a desertified grassland,we investigated the C accumulation in the total and light fractions of the soil organic matter from 2005 to 2013 during natural restoration.To a depth of 20 cm,the light fraction organic carbon（LFOC） storage increased by 221 g C/m2（84%） and the total soil organic carbon（SOC） storage increased by 435 g C/m2（55%）.The light fraction dry matter content represented a small proportion of the total soil mass（ranging from 0.74% in 2005 to 1.39% in 2013）,but the proportion of total SOC storage accounted for by LFOC was remarkable（ranging from 33% to 40%）.The C sequestration averaged 28 g C/（m2·a） for LFOC and 54 g C/（m2·a） for total SOC.The total SOC was strongly and significantly positively linearly related to the light fraction dry matter content and the proportions of fine sand and silt＋clay.The light fraction organic matter played a major role in total SOC sequestration.Our results suggest that grazing exclusion can restore desertified grassland and has a high potential for sequestering SOC in the semiarid Horqin Sandy Land.

Soil Fertility Self-development Under Ecological Restoration in the Zhuxi Watershed in the Red Soil Hilly Region of China

Current methods that utilize simple data or models to judge whether soil fertility can selfdevelop are not sufficiently rigorous. A new framework has been set up using catastrophe theory, laboratory experiment, field work, and 3S(Geographic information system, Global positioning system, and Remote sensing) to explore soil fertility catastrophe under ecological restoration, discriminate whether soil fertility can self-develop, and propose adjustment of ecological restoration measures in the Zhuxi watershed of Changting County, Fujian Province, China, which is a typical representative of the red soil hilly region of China. The results show that: 1) the soil fertility is obviously improved through the four ecological restoration measures, which impels soil fertility catastrophe. Among 89 soil samples, catastrophic soil samples and stable soil samples account for 26(29.21%) and 63(70.79%) of the samples, respectively. The four ecological restoration measures are listed in the order lowquality forest improvement > arbor–bush–herb mixed plantation > orchard improvement > closing measures according to the proportions of catastrophic soil samples. A typical soil sample in Bashilihe that can self-develop is selected as the criterion to judge the upper lobe and lower lobe of soil fertility in the process surface of the Cusp catastrophe model. Twenty-six(29.21%) were in the middle lobe, 10(11.24%) were in the upper lobe, and 53(70.79%) were in the lower lobe. The catastrophic direction of 26 catastrophic soil samples is to the upper lobe according to soil and water loss change as well as fieldwork. There is a significant positive correlation of Δ with soil and water loss change, and the lower soil and water loss relates to higher catastrophic probability. 2) Soil fertility self-development could be regionalized as "Soil fertility can self-develop" whose area was 12.74 km2(28.33%) distributed mainly in the leftmost and rightmost parts, "Soil fertility tends to self-develop" whose area was 11.63 km2(25.89%) distributed mainly in the middle part, and "Soil fertility cannot self-develop" whose area was 20.58 km2(45.78%) distributed mainly between the above two types. 3) There is no need to take ecological restoration measures and excessive human interference should be avoided in the future in regions of "Soil fertility can self-develop" and "Soil fertility tends to self-develop," and ecological restoration measures should be taken in region of "Soil fertility cannot self-develop." 4) We suggest withdrawal and implementation of ecological restoration measures should be incorporated into the evaluation criteria of ecological restoration to avoid misuse of funds.

The ecohydrology of the soil-vegetation system restoration in arid zones: a review

Arid zones, which cover approximately 40 percent of the earth’s land surface, support complicated and widely varied ecological systems. As such, arid zones are an important composition of the global terrestrial ecosystem, and water is the key and abiotic lim-ited factor in ecosystem-driven processes in these areas. Ecohydrology is a new cross discipline that provides, in an objective and comprehensive manner, novel ideas and approaches to the evaluation of the interaction and feedback mechanisms involved in the soil–vegetation systems in arid zones. In addition, ecohydrology provides a theoretical basis of ecological restoration that is cen-tered on vegetation construction. In this paper, long-term monitoring and local observations in the transitional belt between a de-sertified steppe and a steppified desert at the Shapotou Desert Research and Experiment Station, Tengger Desert, in northern China, were evaluated. The primary achievements and related research progress regarding ecohydrology in arid zones were analyzed and summarized, as a keystone, and the response of soil ecohydrological processes to the changes in the species composition, structure, and function of sandland vegetation was discussed. Meanwhile, the long-term ecological effects and mechanism of regulation of vegetation on soil habitat and on water-cycling were considered. As a vital participant in the ecohydrological processes of soil–vegetation systems, the studies on biological soil crusts was also summarized, and related theoretical models of restoration based on the water balance was reviewed.

Vertical distribution of Artemisia halodendron root system in relation to soil properties in Horqin Sandy Land, NE China

Root distribution plays an important role in both vegetation establishment and restoration of degraded land through in-fluencing soil property and vegetation growth. Root distribution at 0-60 cm depth of A. halodendron was investigated in Horqin Sandy Land. Soil organic carbon （SOC） and nitrogen （SN） concentration as well as carbon and nitrogen in root biomass and necromass were measured. Root length density （RLD） was estimated. Total root biomass, necromass and the RLD at 0-60 cm depth was 172 g/m^2, 245 g/m^2, and 368 m/m^2, respectively. Both biomass and necromass of A. halodendron roots decreased with soil depth, live roots were mainly at 0-20 cm （76% of biomass and 63% of root length）, while 73% of the necromass was within 0-30 cm depth. N concentration of roots （biomass and necromass） was about 1.0% and 1.5%, respectively. There were significant differences in SOC concentration between soil layers, but insignificant for SN. Soil C/N ratio decreased with depth （P〈0.05）. C and N storage for belowground system at 0-60 cm decreased markedly with depth; 41.4% of C and 31.7% of N were allocated to the 0-10 cm layer. Root bio- and necromass together contained similar amount of C to that of the soil itself in the top layer. N stock was dominated by soil nitrogen at all depths, but more so in deeper layers. It is clear that differentiating between soil layers will aid in interpreting A. halodendron efficiency in soil restoration in sandy land.

Facultative-anaerobic microbial digestion of coal preparation waste and use of effluent solids to enhance plant growth in a sandy soil

Coal preparation solid waste,which is a major environmental issue for coal-producing areas in China,may be microbiologically digested and transformed into a product suitable as a soil amendment to increase soil organic matter content and prevent and enhance plant/crop growth.Coal preparation waste collected from a coal sorting plant in Inner Mongolia,China was digested in bioreactors inoculated with microbial enrichments prepared from activated sludge and cow manure.The effluent solids from the coal preparation waste bioreactors were analyzed for their suitability as organic soil amendments,which complied with China standards.Plant growth tests were conducted in sandy soil from a semi-arid region in Colorado,which was amended with the effluent solids.Kentucky bluegrass(Poa pratensis L.)and chives(Allium schoenoprasum)were used as the representative plants for the growth tests,where results indicated substantially higher yields of Kentucky bluegrass and chives for the sandy soils amended with the effluent solids when compared to a commercial organic fertilizer.The number and average length of Kentucky bluegrass shoots were 10 and 5.1 times higher,respectively,in soils amended with the effluent solids.Similarly,the number and average length of chives shoots were 10 and 1.7 times higher,respectively,in soils amended with the effluent solids.Overall,the microbial digestion of coal preparation waste for application as an organic soil amendment is a viable alternative and beneficial use of coal preparation solid waste.

Effects of Different Organic Residues on Rice Yield and Soil Quality

Calcaric regosols are a valuable land resource, distributed widely across western China. Soil quality has deteriorated considerably in recent years owing to the blind pursuit of economic benefits. A 2-year field experiment was carried out to evaluate the effects of using spent mushroom compost, leguminous plant (Vicia sepium L.) compost, and a combination of the two (at a 1:1 and 2:1 ratio), on rice yield and soil quality in a suburb of China. Vicia sepium L. composted with spent mushroom compost at a 1:1 ratio produced the highest grain and stover yield, grain and stover phosphorus concentration, and phosphorus uptake of rice; they were 56.5%, 93.2%, 89.3%, 198.6% and 22.2% greater than control soil, respectively. The 2:1 ratio (Vicia sepium L.: spent mushroom compost) produced the highest grain N concentration, stover N concentration, and N uptake; they were 31.6%, 31.4%, and 40.7% higher than control, respectively. Soil physical, chemical, and environmental properties were improved with the application of Vicia sepium L. composted with spent mushroom compost at a 2:1 ratio. In particular, soil water-stable aggregates, organic carbon, particulate organic carbon, total nitrogen, available potassium, and cation exchange capacity increased, whereas bulk density, pH, and phytoavailable heavy metals decreased. This organic treatment is beneficial to improve soil quality indicators, and contribute to soil restoration.

Control Approaches to Soil Pollution from Heavy Metals

With the continuous development of human society and economy and the continuous progress of industrial technology,more and more pollutants are discharged into the natural environment,and soil environment is also affected at the same time. Among pollutants leading to soil pollution,heavy metals have resulted in most serious soil pollution. Here,many control and restoration approaches to soil pollution from heavy metals are proposed,and characteristics and applicable conditions of various methods are compared,so as to provide theoretical references for the control and restoration of soil pollution from heavy metals in future.

Remediation of di(2-ethylhexyl)phthalate(DEHP)contaminated black soil by freeze-thaw aging biochar

Di(2-ethylhexyl)phthalate(DEHP),a complex structure with high toxicity,is a common organic pollutant.This study investigated the effects of fresh biochar(FBC),and freeze-thaw cycled aged biochar(FTC-BC)on DEHP-contaminated soils using a pot experiment.The specific surface area of FBC increased from 145.20 to 303.50 m~2/g,and oxygen-containing functional groups increased from 1.26 to 1.48 mol/g after freeze-thaw cycles,greatly enhancing the adsorption of DEHP by biochar in the soil.The comprehensive radar chart evaluation showed that FBC and FTC-BC reduced DEHP growth stress and improved the soil properties.Compared with FBC,FTC-BC performed better in protecting the normal growth of pakchoi and improving soil properties.In addition,the application of biochar increased the diversity and abundance of bacteria in the DEHP-contaminated soil and changed the composition of the soil bacterial community.The partial least squares path model(PLS-PM)showed that adding biochar as a soil remediation agent significantly positively impacted soil nutrients and indirectly reduced the DEHP levels in soil and plants by increasing soil microbial diversity.Compared with FBC,FTC-BC creates a more satisfactory living environment for microorganisms and has a better effect on the degradation of DEHP in the soil.This study provides a theoretical basis for future biochar remediation of DEHP-contaminated soils in cold high-latitude regions.

Effects of indigenous woody plantations on total nutrients of mine spoil in Singrauli Coalfield,India

A study was conducted on high-density young plantations of three native trees （Albizia lebbeck, Albizia. procera and Tectona grandis） and one native woody grass species （Dendrocalamus strictus） to examine their influence on total nutrient concentrations of coal mine spoil during early phase of plantation establishment. Soil samples were analyzed for total organic carbon （SOC）, Kjeldahl nitrogen （TKN） and phosphorus （TP） at spoil depths of 0-10 and 10-20 cm under 4- and 5-year-old plantations of all species. A significant effect on concentrations of total SOC, TKN and TP were observed due to plantation age, species and soil depth. However, corresponding con- centrations （SOC, TKN and TP） were substantially lower at spoil profile of 10-20 cm. In comparison, plantation ofA. lebbeck showed greater SOC and nutrient concentrations followed by D. strictus, A. procera and T. grandis, respectively. Therefore, present study clearly indicates attributing qualities of plantation towards improving redeveloping soil of mine spoil varied with species.

Vegetation characteristics and soil properties in grazing exclusion areas of the Inner Mongolia desert steppe

In arid and semi-arid desert steppe areas,grazing exclusion with fencing is widely regarded as an effective strategy for restoring degraded vegetation and enhancing the quality of degraded soil.In this study,we hypothesized that grazing exclusion caused by fencing enhances both vegetation and soil properties,and that the longer an area is fenced,the more considerable the improvement.We conducted an observational study wherein random sampling was utilized to select 9 plots fenced for ten or more years,25 plots fenced for four to nine years,25 plots fenced for one to three years and 29 free-grazing plots within an area of approximately 63,000 km^(2)of Inner Mongolia desert steppe.A one-way ANOVA revealed no significant differences in the characteristics of grassland vegetation or soil properties between grasslands fenced for one to three years and free-grazing grassland.After 4 years of fencing,noticeable increases in above-ground biomass,litter content,Simpson index,soil organic carbon,and available nitrogen were observed.Significant positive differences in vegetation coverage,height,species richness,soil available phosphorus,and available potassium were associated with plots with a minimum of 10 years of fencing.The soil layer with the greatest difference in the fenced-in areas for soil organic carbon was at 0-25 cm.For available nitrogen and available phosphorus,fencing produced the most significant differences in the 0-20 cm soil layer,while for available potassium,fencing produced the most significant differences in the 0-30 cm soil layer.However,the fencing did not indicate any statistically significant differences in terms of clay,silt,and sand content in any soil layer.The data support our hypothesis that grazing exclusion improves both vegetation and soil properties,and that longer periods of grazing exclusion result in greater degrees of improvement.This research offers technical guidance for the reasonable choice of fencing time across a vast area of the Inner Mongolian desert steppe.

Influences of Agricultural Practices in the Canton Erde-Pala Chad Vegetation

The study, conducted in the Canton Erd6-Pala Chad, aims to i） list the different cultural practices, ii） study their impact on the vegetation and iii） determine the methods of co-management of these cultural practices. The surveys were realized on 50 households in the village and phytosociological plants in corn, millet, cotton and peanuts cultures. The data analysis by statgraphic and Excel and Principal Component Analysis （PCA） showed that maize production （1,200 kg/ha） ranked first at the expense of cotton （640 kg/ha）. They negatively affect climate change （temperature increase （26%）, rain drop （20%）, land reclamation （18%） and flooding （12%））. Surveys of vegetation on three acres cotton fields （76.17%）, millet （81.06%）, corn （80.32%） and groundnut （83.56%） showed that there is no significant difference （P = 0.05） on the specific contribution of wood of different types of farming practices. Adventists species herbacious like Thelepogon elegans （27.84%）, Hyptis spicigera （19.31%）, Teramnus labialis （15.86%） have most important contributions in specific cultures. Methods of crop treatments have a destructive impact on the environment and the loss of biodiversity and the invasion of crops by adventists. Co-management, crop rotation, association of cultures, community forest management, agroforestry and training farmers in the use of inputs will reduce the potential risks of farming practices.

The influence of desiccation on the recovery process of nitrogenase activity in restored biological soil crusts

Dear Editor,Biological soil crusts(BSCs),a layered structure formed by associations of soil organisms and topsoil,dominate arid and semiarid areas and serve important ecological functions in these areas(Eldridge and Greene,1994).Nitrogen fixation by BSCs is the main source of N in arid and semi-arid ecosystems.Desiccation is the most notable factor that influences BSCs,which recover physiological activity only after moistening.By influencing the amount of carbohydrates,

Volatile organic compound emission and biochemical properties of degraded Ultisols ameliorated by no tillage and liming

TTie Ultisols in the Rana de Canamero area in Southwest Spain showed aluminum(Al)phytotoxicity,and the clearance of natural vegetation and decades of intensive conventional agriculture caused the deplation of soil organic matter(SOM).Therefore,we studied the long-term effects of no tillage and liming using sugar beet foam(SF)and red gypsum(RG),alone or in combination,on the restoration of Ultisols affected by acidification,Al phytotoxicity,and SOM depletion.We measured the main soil chemical properties,soil microbial biomass,soil enzyme activities involved in carbon,nitrogen,phosphorus,and sulfur mineralization,and the emission of volatile organic compounds(VOCs).The results indicated that liming effectively neutralized the soil acidity in the long term and,in combination with no tillage,significantly increased soil microbial biomass and enzyme activities.Twenty-three VOCs were detected using the proton transfer reaction-time of flight(PTR-ToF)technique,and both liming and tillage changed the VOC emission patterns.The greatest difference in VOC emission pattern was observed between no-tilled un-amended soils and tilled lime-amended soils,suggesting the activation of different metabolic pathways within the microbial communities of soils under different management.Differences in VOC emission patterns could be attributed to the decomposition of carbohydrates,which were also sustained by the higher enzyme activities in the lime-amended soils.