Preliminary Study on Biological Characteristics of Degraded Soil Ecosystems in Dry Hot Valley of the Jinsha River

Distribution characteristics of soil animals, microorganisms and enzymatic activity were studied in the dry red soil and Vertisol ecosystems with different degradation degrees in the Yuanmou dry hot valley of the Jinsha River, China. Results showed that Hymenoptera, Araneae and Collembola were the dominant groups of soil animals in the plots studied. The numbers of groups and individuals and density of soil animals in the dry red soil series were higher than those in the Vertisol series, and the numbers of individuals and density of soil animals decreased with the degree of soil degradation. Bacteria dominated microbiocoenosis not only in the dry red soils but also in the Vertisols. Microbial numbers of the dry red soil series were higher than those of Vertisol series, and decreased with the degree of soil degradation. The activities of catalase, invertase, urease and alkaline phosphatase declined with the degradation degree and showed a significant decline with depth in the profiles of both the dry red soils and the Vertisols, but activities of polyphenol oxidase and acid and neutral phosphatase showed the same tendencies only in the Vertisols. It was concluded that the characteristics of soil animals, microorganisms and enzymatic activity could be used as the bio-indicators to show the degradation degree of the dry red soils and Vertisols. Correlation among these soil bio-indicators was highly significant.

Environmental effect of vegetation restoration on degraded ecosystem in low subtropical China

The environmental effect of degraded ecosystem's vegetation restoration in low subtropical China was studied. Results indicated that the vegetation recovery on degraded lands significantly ameliorates surrounding environment, increases species diversity, improves soil structure, raises soil fertility, enhances productivity, and promotes regional agricultural production and social economic development dramatically. Through the combining engineering and biological measures, the restoration of degraded ecosystem in low subtropical area is possible and economical. The restoration experience in Xiaoliang, Wuhua and other sites are valuable for other degraded subtropical area was introduced.

Quantifying land degradation in the Zoige Basin,NE Tibetan Plateau using satellite remote sensing data

Considerable efforts have been dedicated to desertification research in the arid and semi-arid drylands of central Asia. However,there are few quantitative studies in conjunction with proper qualitative evaluation concerning land degradation and aeolian activity in the alpine realm. In this study,spectral information from two Landsat-5 TM scenes(04.08.1994 and 28.07.2009,respectively) was combined with reference information obtained in the field to run supervised classifications of eight landscape types for both time steps. Subsequently,the temporal and spatial patterns of the alpine wetlands/grasslands evolutions in the Zoige Basin were quantified and assessed based on these two classification maps. The most conspicuous change is the sharp increase of ~627 km^2 degraded meadow. Concerning other land-covers,shallow wetland increases ~107 km^2 and aeolian sediments(mobile dunes and sand sheets) have an increase of ~30 km^2. Considering the deterioration,an obvious decrease of ~440 km^2 degraded wetland can be observed. Likewise,decrease of deep wetland(~78 km^2),humid meadow(~80 km^2) and undisturbed meadow(~88 km^2) were determined. These entire evolution matrixes undoubtedly hint a deteriorating tendency of the Zoige Basin ecosystem,which is characterized by significantly declined proportion of intact wetlands,meadow,rangeland and a considerable increase ofdegraded meadow and larger areas of mobile dunes. In particular,not only temporal alteration of the landcover categories,the spatial and topographical characteristics of the land degradation also deserves more attention. In the alpine rangelands,the higher terraces of the river channels along with their slopes are more liable to the degradation and desertification. This tendency has significantly impeded the nomadic and agriculture activities. The set of anthropozoogenic factors encompassing enclosures,overgrazing and trampling,rodent damaging and exceedingly ditching in the wetlands are assumed to be the main controlling mechanisms for the landscape degradation. A suite of strict protection policies is urgent and indispensable for self-regulation and restoration of the alpine meadow ecosystem. Controlling the size of livestock,less ditching in the rangeland,and the launching of a more strict nature reserve management by adjacent Ruoergai,Maqu and Hongyuan Counties would be practical and efficacious in achieving these objectives.

Conservation and restoration of degraded ecosystems in arid and semi-arid areas of northwest China

In "West Development" of China, one of the most important activities is the Natural Forest Protection Program, designed to swiftly convert the focus of management and utilization of the natural forests from a timber orientation towards forest conservation, sustainable management and environmental protection. The project covered almost all the arid and semi-arid regions in Northwest region. Accompanying this great campaign this paper studied the conservation and restoration model of degraded ecosystems in arid and semi-arid lands in Northwest China. The past practices have resulted in considerably natural forest degradation and loss through land conversion (primarily for agriculture), over-harvesting, inadequate reforestation and lack of protection. The consequences have been the loss of soil and water resources, diminished timber production capacity on a sustainable basis, and environmental losses. This paper applied Aronson’s restoration model and proposed the conservation, restoration, re-allocation and preservation program for the implementation of environmental improvement and natural forest conservation.

The method on recovery of forest vegetation in degraded ecosystem in tropical and subtropical waste lowland in Guangdong

The aim of this paper is to discuss the reasonable method to set up the man-made ecosystem where the high productivity, high economic effects and ecological efficiencies, continual resources and suitable environment could be obtained.

Evaluation of the Effects of Implementing Degraded Grassland Ecosystem Restoration Technology: A Case Study on Technology for Returning Grazing Land to Grassland

Restoring degraded grassland ecosystems is of great significance for the sustainable development of grassland ecological service functions and the sustainable and healthy development of regional economies and societies. Returning grazing land to grassland technology（RGLGT） is an important strategic technology for restoring degraded grassland ecosystems and achieving the sustainable development of the society and economy of pastoral areas in China. Researching the comprehensive evaluation system of the effects of RGLGT has an important significance for evaluating and adjusting national ecological policy. Based on collecting sample surveys from 221 farmers in 16 villages of 4 towns of Yanchi County, Ningxia Hui Autonomous Region in 2017, a model for evaluating the effects of implementing RGLGT was developed. The model included the characteristics of the technology, the ecological and social benefits of the technology, and the sustainability and economic benefits of the technology, it was used to complete a comprehensive effects evaluation of implementing RGLGT in Yanchi County that was based on use of the Analytic Hierarchy Process（AHP） method. The results showed that the comprehensive effect of implementing RGLGT is good overall and had a score of 0.5946. In terms of specific effects ranked from high to low, these were the ecological and social benefits of the technology, the economic benefits, the sustainability and the characteristics themselves. The implementation of RGLGT has resulted in good ecological and social benefits and economic benefits, but sustainability and characteristics of the technology are weak.

Degraded Ecosystem and its Rehabilitating Measures in Sandy Areas of North China

Ecosystem degradation occurs in parallel with desertification process in sandy areas of North China. The vast sandy areas in North China are characterized with flexible environments and fragile ecosystems as well as intensive human activities. Due to the annual precipitation gradient decreases from east to west in North China, the whole sandy region falls into 3 main climatic zones: arid, semi-arid and dry sub-humid zones.The ecosystems in each type of climatic zones are different in climatic conditions, human activities, cultural dimensions, vegetation covers, landscapes, and causes and processes of ecosystem degradation. Therefore, the most effective rehabilitation measures of degraded ecosystems in different types of the climatic zones are also different. For the arid sandy areas, vegetation rehabilitation of degraded ecosystems needs to be completely closed, assisting with artificial measures, such as plantation, irrigation or others. For semi-arid sandy areas, the effective measures of vegetation rehabilitation of degraded ecosystems include increasing of proportion of forests and rangelands and limitation of reclamation; reducing the carrying capacity of livestock on unit area of rangelands and growth of fodder plants; and plantation on the lowlands between sand dunes. For the dry sub-humid areas, the most effective measure is enclosure of degraded ecosystems combined with plantation, and in some cases, just stop uses by grazing or reclamation.

Synergies between microsites of plant communities and steady-stage alpine meadows on the Qinghai-Tibetan Plateau

Background:Due to the effects of climate change and overgrazing in recent decades,alternative stable states in the alpine Kobresia meadow degradation process have coexisted in the same geographical and climatic environment,with variations occurring among microsites.Methods:We used a space-for-time substitution approach to explore the synergies of microsite variation according to its numerical characteristics and the proportion of each stable state at various stages of succession in alpine Kobresia meadows on the Qinghai-Tibetan Plateau.Results:(1)The highest average aboveground biomass in summer was 196.2±20.3 gm^(-2),with significantly higher levels of biomass in≤3.65 sheep unit ha^(-1) than in other levels of grazing intensity,while the parameters showed no significant differences among grazing intensity levels in>3.65 sheep unit ha^(-1).(2)The importance of plant functional groups,aboveground biomass,and niche breadth of Poaceae and Cyperaceae significantly decreased as the grazing intensity increased.(3)The effects of≥0°C accumulated temperature,total precipitation,altitude,longitude,and latitude cumulatively contributed less than 20%of the variation in the distribution of functional group characteristics across microsites.Conclusions:(1)Overgrazing decreases primary production in alpine Kobresia meadows,but ecosystem responses regulate plant community structure and botanical components so as to partially counteract grazing disturbance.(2)Overgrazing changed the proportion of microsites,which in turn led to regime shift in the plant community and subsequent synergies between the microsites of plant communities and their stable states.

Using the response-effect trait framework to disentangle the effects of environmental change on the ecosystem services

Functional traits play a vital role in mediating the responses of ecosystem services to environmental changes and in predicting the functioning of the ecosystem.However,the connection between functional traits and ecosystem services has become increasingly intricate due to climate change and human activities for degraded ecosystems.To investigate this relationship,we selected 27 sampling sites in the Yanhe River Basin of the Chinese Loess Plateau,each containing two types of vegetation ecosystems:natural vegetation and artificial vegetation ecosystems.At each sampling site,we measured ecosystem services and calculated the composition index of community traits.We established a response–effect trait framework that included environmental factors such as climate,elevation and human activities.Our results showed that leaf tissue density(LTD)was the overlapping response and effect trait when responding to climate change.LTD is positively correlated with mean annual temperature and negatively correlated with supporting services.Under the influence of human activities,leaf nitrogen content and leaf dry matter content were carriers of environmental change.Comparing the two vegetation ecosystems,the relationship between functional traits and ecosystem services showed divergent patterns,indicating that human activities increased the uncertainty of the relationship between functional traits and ecosystem services.Trait-based ecology holds promise for enhancing predictions of ecosystem services responses to environmental changes.However,the predictive ability is influenced by the complexity of environmental changes.In conclusion,our study highlights the importance of understanding the complex connection between functional traits and ecosystem services in response to climate changes and human activities.

Retention and redistribution of biological legacies generate resource sinks in silvopastoral systems of Arid Chaco forests

Background:Forests are used for multiple purposes worldwide,which often include timber harvest,firewood extraction and livestock raising.An excessive pressure on multipurpose systems may decrease soil cover,promoting soil erosion and causing the loss of other resources,as litter and seeds.Retention forestry practices can help to decrease or mitigate resource loss in the managed stands.Specifically,retaining and redistributing biological legacies(e.g.logs,branches,woody debris)at strategic locations can create sediment,litter,and seed-sinks in the silvopastoral systems.In addition,grazing management could increase or,even,decrease the success of this practice.In this study,we assessed the effect of branch barriers and grazing management on resource run-off/runon processes in silvopastoral systems of Arid Chaco(Córdoba,Argentina).To do this,a 2-ha area was divided in two paddocks that were randomly assigned to different grazing managements:winter vs.continuous grazing.We randomly selected 22 water run-off paths in each paddock,and in the half of them,we build elongated branch piles.In each run-off path(with and without branch barriers),we recorded the amount of accumulated and lost sediment(during the rainy season),litter biomass,germinable seed bank,richness and cover of plant species,and richness and density of seedlings and saplings of woody species.Results:Branch barriers promoted sediment accumulation during the first and the second year of the study,depending on grazing management.The temporal and spatial scale of the effect of the branch barriers also depended on grazing management.Branch barriers also trapped litter and seeds,which may have increased the richness and density of seedlings and saplings of woody species.Conclusions:By intercepting the dominant flow of erosive agents,branch barriers trapped sediment,litter,and propagules of different species.A greater amount of sediment and litter would have improved microsite quality,favouring seed germination and seedling emergence of tree and shrub species,which are key to maintain and/or reconstitute the structure and composition of the forest community in the long term.Therefore,redistributing biological legacies at strategic locations can be a useful and cost-less retention forestry practice to be applied in multipurpose forest management and conservation strategies.

Artificial Management Improves Soil Moisture, C, N and P in an Alpine Sandy Meadow of Western China

Regeneration of degraded grassland ecosystems is a significant issue in restoration ecology globally. To understand the effects of artificial management measures on alpine meadows, we surveyed topsoil properties including moisture, organic carbon (SOC), nitrogen (N), and phosphorus (P) contents five years after fencing and fencing + reseeding management practices in a sandy meadow in the eastern Qinghai-Tibetan Plateau, northwestern China. Both the fencing and fencing + reseeding management practices significantly increased soil moisture storage, SOC, total N, available N, total P, and available P, as compared to the unmanaged control. Fencing plus reseeding was more effective than fencing alone for improving soil C, N, and P contents. These suggested that rehabilitation by reseeding and fencing generally had favorable effects on the soil properties in degraded sandy alpine meadows, and was an effective approach for restoration of degraded meadow ecosystems of the Qinghai-Tibetan Plateau.