Abstract:The variation features of soil- plant system in the natural restoration processes of deg raded sandy grassland in the Horqin sandy land af ter 5 years of exclusive grazing by a nimals are studied.In the mea ntime, the interacting deg ree between soil properties and plant cha racteristics are analyzed.The result s show that: (1) As moving sand was turned into fixed sandy land, the species diversity in plant communities, vegetatio n cov er, underg round root volume and surface litter residue tended to increase.The measured values of β diversity demo nst ra te tha t as semi fluid sand was restored to semi fixed sand, The turnover rate of plants increased and the chang es in plant community structure became evident.(2) In the natural restoration processes of degraded sandy grassland, the structure of surface soil layer significantly improved and the availability of soil nutrients correspondingly enhanced.(3) Correlation analy ses show that there is a close correlation between to psoil physiochemical properties and plant cha racteristic values of the sandy grassland.This shows that the restoration processes of degraded sandy grassla nd are virtually a synergi stically evolutional processes of soil-plant system, the key restoration phase of plant diversity lags behind the key restoration phase of soil environment in the processes.

Abstract:Debris flow waste-shoal land, with proper sunshine and abundant water resource and gentle slope, is a kind of land resource in Jiangjia gully.In order to exploit the debris flow waste-shoal land, the soil fertility properties are studied.The results indicate that, (1) The soil of debris flow waste-shoal land is stoned and sanded seriously.The power of absorbing and supplying moisture and nutrients is low, which is concerned on soil layers and soil particle composition.(2) The microaggregate of the debris flow waste-shoal land is less, mainly distributed in 0.02 to 0.002 mm in the rice-field topsoil and in 0.25 to 0.05 mm in the dry land.(3) The soil nutrient is poor.Organic matter, total N, total P, available N, available P and available K are lack seriously.Wherever total K is abundant, and the applications of organic and inorganic fertilizer, and siltigation are advantageous to improve the soil synthetic fertility.

Abstract:Using artificial experiment, the "fertilization function" of CO₂ enrichment on Aneurolepidium chinensis and Stipa baicalensis is analyzed.The results showed that the biomass increased with CO₂ concentration enrichment, and their total biomass increased by 40.0% and 45.0%.The impacts of soil drought on growth and accumulation of dry matter of Aneurolepidium chinensis and Stipa baicalensis were negative, and these negative impacts were enhanced with drought aggravating.Total biomass decreased by about 16% and 30% under light drought, and decreased by about 44% and 35% under heavy drought.The fertilization effect on the two species weakened under soil drought, and it was more obvious on Aneurolepidium chinensis than on Stipa baicalensis.

Abstract:The Qinghai-Tibetan plateau is one of the regions with the least man-made disturbance in the world.The harsh natural conditions of high elevation, cold and drought climate and oxygen deficiency result in the fact that the plateau vegetation and ecosystems are unique and very fragile and susceptive to man- made disturbance.The construction of the railway will intensify soil erosion along the railway line to a certain degree.The map of soil erosion condition in the section from Tanggula mountain pass to Lhasa city in the range of 50 kilometers each side along the line was drawn by using the techniques of remote sensing and geographic information system.Based on analysis of the status of soil and water loss, and the influence of the railway construction projects, the changes of the types, intensities and the total amount of the soil erosion caused by the construction are predicted, and the damage from soil erosion is analyzed.

Abstract:Saturation is derived from water content and dry density of soil.There are two patterns of varying process of saturation, one is related with variation of moisture state, other is related with density state.There are 23 groups UU triaxial compression tested with experimental specimens in six different moisture states and four density states were conducted according to five classes of surround pressure as 100, 200, 300, 450 and 600 kPa.Experimental results show that shear strength parameters of remolded unsaturated cohesive soil vary regularly in certain extent with saturation, but not available to be presented by one or two simple functions.Cohesion has a strong nonlinear relation with moisture state related saturation and a quasi-linear relation with density state related saturation respectively.Internal friction angle has a strong nonlinear relation with moisture state related saturation and a weak nonlinear relation with density state related saturation respectively.

Abstract:The problem of producing forest withdrawing from furrow, which is the main measurement of soil water conservation, is analyzed particularly as a sample at Guidong county in Luoxiao mountain area.The method of producing forest from furrow may reduce the soil erosion.But the variety of forest is singleness and cannot arrive the effect of soil and water conservation and the effect of zoology expected.It may be existed for long time due to the lack of short-term economic benefit.For the good effect of soil and water conservation and high economic benefit, the local environment must be studied, and the species must be chosen to make the arbor and herbage grow up together.

Abstract:Located experiment in 3 years indicates that Humulus scandens is not only a kind of good forage grass resources, but also a soil and water conservation herb which has strong capacity to fix and protect soil.It is a kind of ideal grass vegetation to afforest barren mountain, slop and gully, to improve ecological environment of the loess plateau.The coverage could be 80% within the seeding year and more than 90% the next year.The result with synthetical calculation and analyzing indicates that the water conserving efficiency of Humulus scandens combined with simply soil and water conservation physical measures is 46%, and the sand reducing efficiency is 75.9%.

Abstract:Seriously degrading land quality and radically decreasing organic matter content are the most significant problems of fruit plantation in red soil hillock.Based on the analysis on the relation between interplanted plants and fruit trees, the structure and function of the model of ecological fruit industry in which the fruit tree plant is dominant, animal husbandry, interplant green manure and protection forest are supplementary, are analyzed systematically.

Abstract:Jiuyuangou catchment is typical of the loess hilly and gully areas, and was identified as an experiment and demonstration base for soil and water conservation in 1953.Since then, comprehensive strategies have been carried out to control soil and water loss with the construction of sediment-storage dams as the main measure.In past 50 years, great achievements have been made in social and economic development and land productivity improvement.The experiences from and problems identified in the construction and operation of sediment-storage dams in Jiuyuangou catchment can provide scientific and technical support and guidance for the construction of sediment-storage dams in the loess hilly and gully areas in the future.

Abstract:The effects of humic acid copolymers on chemical properties of the soil are studied.The experimental results showed that specific surface area, the charge amount and the cation exchange capacity of the soil increased with dose of the copolymers in the soil.The effect of acrylic acid amount of the copolymers on specific area was different from that on the charge amount and the cation exchange capacity of the soil.The pH of the soil amended was raised.

Abstract:Runoff plots are very important for soil erosion study.The measurement of sediment content is a key part in the process of soil loss calculation.It is so difficult for traditional measurement method to measure sandy particle that sediment content measured is apparently less than true value.The study was conducted in collecting tank at Shixia watershed, Miyun county of Beijing city.The six different sediment content including about 4, 12, 30, 60, 90, 120 kg/m³ were put into collecting tank with about 0.7 m deep water, respectively.The traditional measurement method and layered measurement were used to measure sand content.The measurement results of these two methods were compared with true sand content.The results show that traditional measurement method underestimated sand content and the relative difference was (-83.05%), while layered measurement method can precisely measure sand content and the relative difference was -2.77%.

Abstract:The stability of sediment storage dams is analyzed with the order of stable safety factor calculation developed in Visual Lisp of AutoCAD.With this method, we can improve engineering designing efficiency and quality.

Abstract:The influence of water absorbing resin on moisture retention properties of soils is studied.After added into soil, the moisture absorbing ability of resin decreased abruptly, resulting in less soil water content increment than expected.The evaporation rate of water in loamy soil increased as resin proportion in soil increased.The evaporation rate of water in sandy soil decreased as resin proportion increased.Adding of water absorbent restricted water infiltration into deep layer and could lead to more evaporation in early stages if applied improperly.

Abstract:Based on definition of artificial barrens, the ecological foundation on making artificial barren ground green is discussed, and five failure causes of which are analyzed, respectively.According to the characters and current situation of artificial barrens, types and reasonable suggestions on construction artificial vegetation on artificial barrens are posed.

Abstract:One-dimensional sediment numerical model is deeply researched and developed.It plays a large role in solving the actual engineering problems.But because of the complexity of sediment movement and the limit of the theories, there still exists some problem to be perfected.Some problems are discussed, and some personal cognitions of authors are brought forward.

Abstract:On May 17, 2002, landslide took place in Nanping county, Fujiang province.The debris flow came into being at foot of the landslide.After investigating the hazard, the cause of landslide are analyzed.The main causes are long-time rainstorm, advantageous relief geologic conditions, and unscientific human activities, etc.Through contrasting the landslide with other hazards, the countermeasures of controlling hazards in the area are put forward.For the sake of avoiding similar tragedies, science popularization education must be strengthened.

Abstract:The arid tendency of agricultural eco-environment needs to innovate radically the existing unreasonable models and outdated ideas of agriculture developing in Ningxia Hui Autonomous Region.The avoiding calamity agriculture should be the new idea to agricultural sustainable development in Ningxia region.Furthermore, the sub-model of drawing the Yellow river irrigable land and the sub-model of southern mountainous area are produced and formed through analyzing the characteristics of avoiding calamity agriculture and based on the conditions of arid calamity and the un-evenly characteristic of inner environmental quality in smaller region.The model of avoiding calamity agriculture is accepted easily in economy, operated easily in management and has high benefits.Especially, it is of great significance to improve agricultural investment environment and to realize regional sustainable development.

Abstract:By means of an investigation on 11 typical watersheds, the benefits of watershed management on loess plateau of Shaanxi province are analyzed.On this basis, the 11 typical watersheds are classified into 5 models to control soil and water loss, and a relatively integral suitable index system for evaluating the benefit of watershed management was developed.By using of AHP and multilevel fuzzy comprehensive evaluation, the benefit of 5 models and 11 typical watersheds are systematically appraised.

Abstract:After introduced economic plant resources and its utilizated status in the loess plateau, the principles of sheltered utilization on economic plant resources in the region are analyzed.And the countermeasures, which can realize sheltered utilization of economic plant resources, are put forward.To realize sheltered utilization on economic plant resources in the loess plateau, the principles ought to be scrupulously abide by as follows.(1) Eco-environment rehabilitation projects are continuously carried out in order to improve ecological system of the region; (2) Based on scheming management of the government, wild resources of economic plants are limited to be utilized and cultivated base on economic plants are encouraged to upbuild; (3) Key technique and practical techniques are tried hardly to develop about comprehensive utilization of economic plants.The countermeasures are put forward: Enhance the research of conservation biology on rare and endangered economic plants in the loess plateau, and set up botany garden and arboretum about wild economic plants; Enhance the research on economic plants introduction and acclimatization, and construct breeding base and spreading system of excellent varieties of economic plants; Enhance engineering research of phytochemistry on economic plants, and develop economic plant industry in order to realize price increment of secondary products.

Abstract:The demonstration model of eco-agriculture has been constructed for 3 years in Yangou small(watershed.) In this course, compound measures were put in practice in large scale, high velocity and great efficiency.Three eco-agriculture modes of high efficient agriculture-byproduct, agriculture-orchard compound and forestry-livestock compound were fostered.The adjustment of countryside industry construction was improved.The stable and high yield of base farmland, forest-bush-grass compounded and small water resource exploitation and high efficient usage were demonstrated and popularized.So Yangou small watershed control degree of soil erosion reached to 49.4 percent.The reducing sand efficiency monitored got to 72 percent.The realized ratio of foodstuff potential was improved to 16～31 percent.The income per people increased 740 Yuan.