渭北旱源地区干旱条件下的造林技术选择与效果分析

针对渭北旱源地区干旱缺水的严峻挑战,本研究深入探索了多种造林技术在该环境下的适应性。通过系统分析地形、土壤与水分状况,我们实施了滴灌、穴贮水及地膜覆盖等技术试验,并长期监测树木成活率、生长态势及土壤水分动态。研究揭示,滴灌技术有效提升了树木成活率与生长速率,成为促进林木繁茂的关键;穴贮水技术则以其卓越的节水性能,尤适用于极度缺水区域;而地膜覆盖技术,则在减少水分蒸发、增强土壤保水能力上展现出显著优势。本研究为渭北旱源地区量身定制了科学的造林策略,依据不同干旱程度灵活选用技术,显著优化了造林效果,为区域生态修复提供了宝贵的实践指导与理论依据。

旱塬果区苹果育果纸袋和膜袋应用效果比较试验

苹果套袋在减少果实中农药残留量,提高果实外观品质等方面具有重要作用,是生产无公害果品的主要途径之一。目前陕西苹果年套袋量已达108亿只,其中纸袋58亿只、膜袋50亿只,而且每年套袋推广量还在成倍增加,套袋技术已被越来越多的果农所接受。为了引导生产者正确选择果袋,促进苹果套袋技术迅速推广,2002年笔者对双层纸袋、单层纸袋、膜袋作了比较试验,总结如下。

Impact of Global Warming on Water Resource in Arid Area of Northwest China

As the unprecedented global warming is under way, the glacier retreat is getting more and more serious. In the inland arid area of Northwest China, due to very scarce precipitation, where there is water, there are oases. And the glacier melt water amounts to 22 % of the total direct supply of the inland river water and is of crucial importance to the survival and development of the oases. In this paper, using both the observed data and the previous research achievements of the glaciers in the inland valley of Northwest China where the oasis depending on the glacier is the only location suitable for human living, the authors describe the glacier retreat trend over the past half century, focusing on discussing the possible impact of the glacier retreat on the melt water runoff that is almost the only water resource efficient to nourish the oases. The authors find that even with increasing amount of water from the glacier with global warming, the water shortage is getting more and more serious and the environment is under a degrading way due to the accelerating economical development. The water shortage is bound to be more serious if the glacier retreat keeps on, especially after the glacier melt water is over its top for the degradedglacier scale. So suggestions are stressed in the end that a new water-saving pattern should be adopted in the area for a sustainable development due to the warming-up induced continuous glacier retreat.

PRESSURE OF WATER SHORTAGE ON AGRICULTURE IN ARID REGION OF CHINA

The arid areas in China are mainly located in North China and NorthwestChina. The North China is the main region for food production. There is 31. 19% of the totalfarmland and 26. 01% of the total population, but only 6. 14% of the available water resources ofChina. Groundwater is over pumped (6. 53 X 10~9m^3 every year) in the regions of Beijing, Tianjin,and Hebei Province, so water supply could not meet the water demand there. The distribution of waterin Northwest China is uneven, some inland rivers and lakes are dried up, and desertification hasexpanded since river water in the upper and middle reaches is diverted for irrigation. Up to 2050,population will be up to 1. 6 X 10~9 in China, and industry will be developed fast, therefore 50% ofthe water supply will be used by industry and resident, and water for agriculture will be decreasedyear by year. In the coming 50 years, water demand for agriculture will be increased by 5. 6 x10^9m^3 in the Huanghe (Yellow) River valley, and by 1. 7 x 10~9m^3 in the Northwest China. It willbe impossible for the Huanghe River to meet the water demand, because it always dried up in the coldhalf year since 1984. To avoid water shortage of agriculture in the arid regions, it is necessaryto divert water from the Changjiang (Yangtze) River in the south of China, and to use waterefficiently. It is the best way to use drip irrigation in agriculture, recycle water in industry andresident use, and control water pollution. Otherwise water shortage in the arid regions willrestrict the development of agriculture in China.

Isotopic composition of precipitation over Arid Northwestern China and its implications for the water vapor origin

In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Precipitation(CHNIP).During the year 2005 and 2006, monthly precipitation samples have been collected and analyzed for the composition of δD and δ18O.The established local meteoric water line δD=7.42δ18O+1.38, based on the 95 obtained monthly composite samples, could be treated as isotopic input function across the region.The deviations of slope and intercept from the Global Meteoric Water Line indicated the specific regional meteorological conditions.The monthly δ18O values were characterized by a positive correlation with surface air temperature(δ18O(‰) =0.33 T(℃)-13.12).The amount effect visualized during summer period(δ18O(‰) =-0.04P(mm)-3.44) though not appeared at a whole yearly-scale.Spatial distributions of δ18O have properly portrayed the atmospheric circulation background in each month over Arid Northwestern China.The quan-titative simulation of δ18O, which involved a Rayleigh fractionation and a kinetic fractionation, demonstrated that the latter one was the dominating function of condensation of raindrops.Furthermore, the raindrop suffered a re-evaporation during falling processes, and the precipitation vapor might have been mixed with a quantity of local recycled water vapor.Multiple linear regression equations and a δ18O-T relation have been gained by using meteorological parameters and δ18O data to evaluate physical controls on the long-term data.The established δ18O-T relation, which has been based on the present-day precipitation, could be considered as a first step of quantitatively reconstructing the historical environmental climate.

Contribution of Adventitious Roots to Water Use Strategy of Juniperus sabina in a Semiarid Area of China

duniperus sabina Linnaeus, an evergreen shrub with prostrate life form, can effectively prevent sand moving and is an important tree species for reforestation in semiarid areas of China. It has laterally distributed adventitious roots and a deeply distributed main root system. To detect water movement between the main root system and adventitious roots, we adopted heat pulse sensors using the Heat Ratio Method, a high precision method for measuring low sap flow rates. Two sensors were implanted in each individual in the stem between the main root system and adventitious roots, and another two in lateral stems distal to all the roots. Positive sap flows during nighttime, even under saturated air moisture conditions, were detected only between the main root system and adventitious roots under drought conditions, and the rate of flow increased as drought progressed and decreased or disappeared after rain events. The results demonstrated the existence of water movement from the main root system to adventitious roots, and combined with the high contribution of nighttime sap flow to transpiration （11%-16%） the results indicate that it also involves the process of hydraulic lift, a water movement from moist subsoil to dry surface soils. Integrated water use strategy between the main root system and adventitious roots via the process of hydraulic lift of soil water maximizes water acquisition efficiency from both subsoil water and water from rain pulses on the soil surface; this increases survivability in the water-limited environment of semiarid areas.

Strategies for enhancing economic growth and ecological sustainability in Xinjiang province, China

In arid regions, fragile ecological environment is an obstacle to economic development; an efficient pattern of eco-economic development could be sought from different strategies in such regions. China＇s Xinjiang province is the most typical arid region in the world, in fact, contradiction among ecological issue and economic development is intense. In this paper, the natural resource condition, social and economic developments are analyzed in Xinjiang province, with emphasis on the economic development stages underpinned by resource superiority after the economic reform era. We argue that： Xinjiang＇s economic development was determined comprehensively by geography, ecological resources, and human activity; however to explore a new development pattern with lower dependence on ecological resources, lower cost, more protection to the environment, higher value added and levels of science and technology and knowledge is a key challenge for future economic development. Based on the comparison between past and present, Green strategies should be exclusively chosen for eco-economic development due to the pressure on ecological resources, and the sustainable developmental green strategies include： ecology stratagem, trade stratagem, structure adjustment stratagem, capital stratagem, human resources stratagem. The key challenge is to provide supportive policy and instructional environment to foster such strategies.

Discussion on an Eco-Agriculture Model in the Semi-Arid Region of China

The semi-arid region of China covers an area of 2.2 x106km2. Water shortage in this region is the core but not the only one factor for the sustainable development of agriculture. Effective application of the energy and all kinds of resources and overall maintenance of the balance of ecological environment must be emphasized for sustainable development of the agriculture in the region. The extensive development of rural yard-economy is the only way to realize the intensive agricultural development there. A model is developed on the basis of our studies in recent years.

Climate Change and Water Resources： Strategies and Practices for Improved Water Management in Arid Countries

Assessment report of the Intergovernmental Panel on Climate Change （IPCC） highlighted the complex linkages between climate change and water. The likely warmer climate induced by the climate change is set to alter hydrological cycle and the shifting pattern of the rainfall would affect the spatial and temporal distribution of runoff, soil moisture, and surface and groundwater reserves. Therefore, there is an urgent need to assess the impacts of climate change on water and devise adaptation measures including management structures and processes by which one can deal with this challenge. The paper highlights with the global overview of climate change impacts on water in the arid region, supported and substantiated through scientific evidence drawn from IPCC reports and other relevant documents. This paper provides an overview of water resource management challenges including transboundary geopolitical concerns documented across the world and emphasizes the importance of an integrated framework for adaptive policy making. Further, it examines the viable water resource management options for various sectors and regions and showcases some of the international best practices in adaptation and mitigation. The paper also explains the complementary role of traditional knowledge in coping with climate change risks and uncertainties and the need for a balanced view in designing adaptation and mitigation strategies.