Evaluation on Ecological Vulnerability of the Vegetation in the Subei Lake Watershed Based on Analytic Hierarchy Process

[ Objective] The research aimed to evaluate ecological vulnerability of the vegetation in the Subei Lake watershed based on analytic hierarchy process （AHP）. [ Method] From actual situation of the vegetation ecology in the Subei Lake watershed, by the established evaluation index system of vegetation ecology, based on AHP, indicator weight at each layer was determined. Comprehensive index method was used to calculate ecological fragility degree of the vegetation in each evaluation unit to evaluate ecological vulnerability of the vegetation. [ Result] Ecological vulnera- bility of the vegetation was divided into four levels, such as extremely fragile, highly fragile, moderately fragile and lowly fragile in the Subei Lake watershed. The extremely fragile area, where buried depth of the groundwater level was generally less than 1.0 meter, distributed in beach zones near the Subei Lake, and its relationship between vegetation and groundwater was close. The lowly fragile areas scattered in the ridge zone around the Subei Lake watershed, where buried depth of the groundwater level was 10.0 -40.0 meters, and their relationship between vegetation growth and groundwater depth was not obvious. Buried depth of groundwater had the most sensitive influence on vegetation ecology, and it was the key factor between utilization of groundwater resources and eco-environment protection in the study area. E Conclusion] The researches provided scientific evidence for regional eco-environment protection, rational development and utilization of water resources, and coordinated development of economy and society.

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.

Remote Sensing Study of Gold Biogeochemical Effects in the Western Guangdong-Hainan Region——A Case Study of the Hetai Gold Deposit

The vegetation has been poisoned by gold in the western Guangdong-Hainan region. The gold content ofthe leaves there is as high as 10-1961 times the abundance, the chlorophyll content is 10%-30% lower thanthat of the vegetation in metamorphic terrains and 10%-20% higher than that in granite terrains, and thecarotenoid content is 10%-44% lower than the background value. The water content of leaves is 10% to 20%lower than the background value. The cells of leaves are deformed and broken. The leaf surface shows colourspots and becomes yellow or dark green. The spectral reflectance of the leaf surface is 5%-30% higher than thebackground value: the spectral shape has shifted 5-15 nm to the short wavelength. The gray scales of eanopyon images of Landsat TM and airborne imaging scanner (AIS) are 10%-100% higher than the backgroundvalues. On Landsat TM and AIS false colour images, plants poisoned by gold display a yellow color, whichdisinguishes them from background plants. According to the spectral and image features of goldbiogeochemical effects, the author has constructed a gold information system and expert prediction system,and thus two gold target areas and two gold prospect areas have been identified rapidly, economically andaccurately in the western Guangdong-Hainan region which is extensively covered by vegetation.

Ecology of the rehabilitation of vegetation on tropical coastal eroded land in Guangdong， China

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Vegetation ecological benefts index (VEBI): a 3D spatial model for evaluating the ecological benefits of vegetation

Urban population explosion may increase ecological environment discomfort,thereby affecting negatively humans’mental and physical performance.Therefore,it is important to detect and monitor vegetation and predict its ecological benefits.The complex composition of urban environment ground objects,such as steel roofs,plastic courts,and building shadows,significantly interferes with vegetation detection and monitoring.The optimized hyperspectral image-based vegetation index(OHSVI)constructed in this study effectively solves this problem.However,it is difficult to accurately predict the ecological benefits of vegetation based on the two-dimensional vegetation information extracted based on remote sensing images;this is related to the three-dimensional(3D)structure of vegetation and the 3D pattern of buildings.Therefore,wefirst proposed the vegetation ecological benefits index(VEBI)based on the 3D structure of vegetation to reveal how vegetation acts on its 3D surroundings.The method was tested in a playground,an academic building,and a parking space.The results showed that the vegetation extraction accuracy of the OHSVI exceeded 93%,which is better than that of the existing indices.Ourfindings suggest that VEBI may be efficient in predicting 3D vegetation ecological benefits combined with remote sensing and lidar datasets.

Climatic Warming and Humidification in the Arid Region of Northwest China: Multi-Scale Characteristics and Impacts on Ecological Vegetation

The climatic warming and humidification observed in the arid region of Northwest China(ARNC) and their impacts on the ecological environment have become an issue of concern. The associated multi-scale characteristics and environmental responses are currently poorly understood. Using data from satellite remote sensing, field observations, and the Coupled Model Intercomparison Project phase 6, this paper systematically analyzes the process and scale characteristics of the climatic warming and humidification in the ARNC and their impacts on ecological vegetation. The results show that not only have temperature and precipitation increased significantly in the ARNC over the past 60 years, but the increasing trend of precipitation is also obviously intensifying. The dryness index, which comprehensively considers the effects of precipitation and temperature, has clearly decreased, and the trend in humidification has increased. Spatially, the trend of temperature increase has occurred over the entire region, while 93.4% of the region has experienced an increase in precipitation, suggesting a spatially consistent climatic warming and humidification throughout the ARNC. Long-term trends and interannual changes in temperature and precipitation dominate the changes in climatic warming and humidification. Compared to interannual variations in temperature, the trend change of temperature contributes more to the overall temperature change. However, the contribution of interannual variations in precipitation is greater than that of the precipitation trend to the overall precipitation change. The current climatic warming and humidification generally promote the growth of ecological vegetation. Since the 1980 s,82.4% of the regional vegetation has thrived. The vegetation index has a significant positive correlation with precipitation and temperature. However, it responds more significantly to interannual precipitation variation, although the vegetation response varies significantly under different types of land use. The warming and humidification of the climate in the ARNC are probably related to intensifications of the westerly wind circulation and ascending air motions.They are expected to continue in the future, although the strength of the changes will probably be insufficient to significantly change the basic climate pattern in the ARNC. The results of this study provide helpful information for decision making related to China's "Belt and Road" development strategies.

Analysis on the ecological benefits of the stream water conveyance to the dried-up river of the lower reaches of Tarim River,China

This paper analyzes the monitored data of the 4 times of stream water conveyances to the river section where the stream flow was cut-off, of 9 groundwater-monitoring sections and 18 vegetation plots in the lower reaches of Tarim River. The results show that the groundwater depth in the lower reaches of Tarim River rose from 9.87 m before the conveyances to 7.74 m and 3.79 m after the first and second conveyances, 3.61 and 3.16 m after the 2 phases of the third conveyance, and 2.66 m after the fourth conveyance. The transverse response scope of groundwater level was gradually enlarged along both sides of the channel of conveyances, i.e., from 450 m in width after the first conveyance to 1050 m after the fourth conveyance, but the response degree of groundwater level was reduced with the increase of the distance away from the channel of conveyances. The composition, distribution and growth status of the natural vegetation are directly related to the groundwater depth. The indexes of Simpson’s biodiversity, McIntosh’s evenness and Margalef’s richness, which reflect the change of the quantity of species and the degree of biodiversity, are reduced from 0.70, 0.48 and 0.90 to 0.26, 0.17 and 0.37 re- spectively along with the drawdown of groundwater level from the upper reaches to the lower reaches. After the stream water conveyances, the natural vegetation in the lower reaches is saved and restored along with the rise of groundwater level, the response scope of vegetation is gradually enlarged, i.e., from 200— 250 m in width after the first conveyance to 800 m after the fourth conveyance. However, there is still a great disparity to the objective of protecting the “Green Corridor”in the lower reaches of Tarim River. Thus, it is suggested to convey the stream water in double-channel way, combine the conveyance with water supply in surface scope, or construct the modern pipe-conveyance network systems so as to save the natural vegetation in an intensive way, achieve the efficient water consumption and speed up the restoration and re- generation of the damaged ecosystems in the lower reaches of Tarim River.

Impacts of revegetation management modes on soil properties and vegetation ecological restoration in degraded sandy grassland in farming-pastoral ecotone

Focusing on the impact of various vegetation management modes on sandy grassland's soil property and vegetation ecological restoration of farming-pastoral ecotone,field surveys and lab analysis were conducted to study the correlation between the characteristics of soil properties and vegetation ecological restoration under four different vegetation management modes,i.e.,unenclosed natural restoration,enclosed natural restoration,unenclosed artificial restoration and enclosed artificial restoration,which have a restoration history of 15 years in the southern edge of the degraded sandy land area of Mu Us Desert in Leilongwan Town,Hengshan County,Shaanxi Province.After 15 years of vegetation restoration,these four vegetation management modes all proved to be useful for improving the vegetation ecological restoration and the soil quality of the degraded sandy grassland not only by enhancing the aboveground vegetation height,coverage and biomass but also increasing the content of soil clay,organic matter,CEC,total nitrogen,available nutrient while reducing soil bulk density.The vegetation ecological restoration effect and soil quality under enclosed or artificial restoration management are better than those of unenclosed or natural restoration management;and the most satisfactory vegetation ecological restoration effects and soil quality can be achieved under the integration of enclosed and artificial restoration management.Severely degraded sandy grassland,during the vegetation restoration,would form an interactional coordinating relationship with the vegetation and soil properties.Vegetation properties as height,coverage and biomass have significant positive correlations with organic matter,CEC,total nitrogen and available nitrogen,phosphorus,and potassium contained in soil.Only the adoption of the strict enclosure system,implementation of aggressive artificial vegetation restoration measures and the realization of the regurgitation-feeding policy of industry towards husbandry can guarantee the gradual restoration of degraded sandy grassland in farming-pastoral ecotone,so that it can continue to play the role of ecological protective screen.

Rehabilitation and improvement of Guilin urbanwater environment: Function-oriented management

Economicdevelopment and population growth havedeeplydamaged the urbanwater environment of Guilin City, China. Main problems involved structuraldamage and functionaldeterioration of the urbanwaters. An integrated technical schemewasdeveloped to rehabilitate the urbanwater environment and to enhance thewaters＇ functionsduring 1998-2008. Improvement ofwaters＇ functions includedwater system reconstruction,water pollution control,water safety assurance, and aquatic ecological restoration. Thewater systemwas reconstructed to connectdifferentwaters and cleanwater supplies to the lakes. Moreover,water pollutionwas controlled to improvewater quality by endogenous pollutant elimination and extraneous pollutant interception. In addition, ecological measures put in place serve to enhancewater system functions and better benefit both nature and humans. The project has brought about sound ecological, economic and social benefits in Guilin City,which can potentially be extended to similar cities.