Trend of China land water storage redistribution at medi- and large-spatial scales in recent five years by satellite gravity observations

The GRACE (Gravity Recovery and Climate Experiment) satellite gravity mission has provided a new method to study land water mass redistribution at medi- and long-spatial scales in recent years. We estimate continental water mass redistribution in China using GRACE observations during 2003 to 2007. The results show some large regions with increase or decrease of land water mass storage in the central northern region, Tibetan Plateau, the Three Gorges region, the place where Qinghai, Sichuan and Gansu provinces meet, and the Altun Mountains region in the Xinjiang Uygur Autonomous Region. In the first two regions, it is obvious that water (ice) mass storages are decreasing. Water mass in the central northern region decreases at a linear rate of 2.4 cm/a equivalent water height, equal to 5.2 billion cubic meters per year during the five years’ period, and water mass depletion in Hebei Province is ∼ 4.5 billion cubic meters per year in the same period, which is consistent with the average water mass depletion of 4.0 billion cubic meters per year of overused underground water in the recent 30 years estimated by Hebei Province Water Resources Bureau. Furthermore, GRACE can detect the water mass accumulation of ∼ 5 cm equivalent water height within the region spreading over about 0.12 million square kilometers due to the Three Gorges dam construction in June 2003. We also find a water mass gain of ∼ 1.1 cm/a in the areas where Qinghai, Sichuan and Gansu provinces meet. This indicates that the climate of these regions has been becoming gradually humid in recent years. Supported by Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-202), National Natural Science Foundation of China (Grant No. 40674038), and Program of Key Laboratory of Space Environment and Geodesy of Ministry of Education of China     

地膜覆盖对半干旱区春小麦光合作用及产量的影响

对半干旱区春小麦进行短期地膜覆盖试验,结果表明：覆膜有利于春小麦光合作用和产量水平的提高,但覆膜时间过长,日光合积累和最终籽粒产量反而有下降的趋势,在研究区,春小麦最佳覆膜时间为播种至三叶期,不必全生育期覆膜。     

敦煌大泉河水环境特征分析

以位于敦煌盆地南部莫高窟区的大泉河为例,分析了极干旱环境条件下小河流的基本特征,研究了该河流的径流量和水质成分的时空变化规律,其目的是合理有效地开发利用戈壁荒漠区极珍贵的水资源,兴利避害,为敦煌莫高窟的保护及旅游事业发展提供服务.     

干热河谷水电站营地绿化植物的选择与配置

以锦屏水电站营地为例,通过对干热河谷这一特殊地域气候、土壤、植被状况的分析,提出了干热河谷地区水电站营地植物的选择原则,以及适合干热河谷地区的主要园林植物,从而为水电站营地建设提供了技术依据.     

西北地区2004年夏旱特征和成因分析

针对西北地区2004年夏季(6和7月)严重干旱,对干旱特征和成因进行了分析.干旱持续之长,范围之广,强度之重,危害之大少有.干旱形成原因主要是500 hPa高度场上乌拉尔山阻塞高压和新疆脊强.亚洲40°N以北和青藏高原东部西风气流强盛,南支槽位置偏南,西太平洋副热带高压偏弱、位置偏东,西北地区上空水汽偏少.这些结果对防灾减灾措施制定有重要作用,也是短期气候预测的重要气候背景.     

干旱半干旱地区土壤矿物组成特征及其环境意义

对处于干旱、半干旱地区的甘肃省15个地点的灰钙土、栗钙土、黑垆土、灰褐土和黄绵土等不同类型土壤剖面进行了机械组成分析、矿物组成显微鉴定和粘土矿物X射线衍射分析.结果表明:土壤机械组成以粉砂为主,粘粒次之;栗钙土、灰钙土、黑钙土和灰褐土等于旱地区典型土壤中表层的粘粒质量分数相对较低,土壤原生矿物组成以石英为主,绿帘石等蚀变矿物质量分数较高,次生矿物含有较高的石膏和方解石等;粘土矿物主要为伊利石、绿泥石、高岭石和蒙脱石.土壤机械组成、矿物组成和粘土矿物组成表明:干旱、半干旱地区土壤为黄土母质,土壤形成条件为碱性环境、较弱的淋滤作用和干冷气候,近代强烈的风蚀作用(或沙尘暴)和大气污染对土壤有一定程度的改造.     

景观结构调整和干旱半干旱区水资源的可持续利用

分析了干旱半干旱区存在的一些生态问题,论述了与干旱半干旱区水资源可持续利用有关的景观生态学理论,其中包括景观连通性、自然干扰、河流廊道和斑块水文功能.在此基础上,提出了一些景观结构调整措施:1)调整水源涵养斑块和耗水斑块面积组成比例和空间分布;2)营建防风林带;3)保护和恢复河流廊道;4)保留景观内水体斑块;5)拆除某些水利设施等.这种景观尺度上的结构调整因其更大的宏观性和整体性优势,将起到农业作物结构调整所不能起到的一些作用,这对改善半干旱区水资源状况和实现半干旱区水资源可持续利用具有重要意义.     

一类捕食食饵模型正解的性质

目的讨论一类具有Beddington—DeAngelis功能反应函数的交叉扩散捕食模型正解的性质。方法利用最大值原理,Harnack不等式,s—Young不等式和Poincarfi不等式研究该模型。结果给出了模型正解的上下界和非常数正解的不存在性。结论在适当条件下该模型不存在非常数正解。     

Aspects of natural history in a sand boa,Eryx muelleri (Erycidae) from arid savannahs in Burkina Faso,Togo, and Nigeria (West Africa)

The ecology of West African arid savannah snakes is still poorly known, especially in regard to the fossorial species. Here, field data on distribution, morphometrics, habitat use and diet are reported for the sand boa Eryx muelleri (Erycidae) from three different countries, i.e. Burkina Faso, Togo and Nigeria. This snake was observed in 21 distinct localities, and a total of 39 individuals was recorded. The species is likely fairly common and locally abundant. Mean body length of snakes was similar among countries and between sexes, but males had proportionately longer tails than females. Body length was significantly positively correlated with both tail length and head length. Adult sex ratio was close to parity. Most of the specimens were found in well-vegetated spots with low percentage of bare soil. There were apparently both ontogenetic and intersexual dietary variations: (1) a single analysed juvenile fed upon a small-sized lizard, whereas adults fed considerably upon young rodents; and (2) females fed exclusively upon young rodents and males upon both lizards and young rodents. In conservation terms, the species is actively exported from Togo for the pet trade, and additional individuals may also be illegally collected in other countries.     

干旱地区水资源服务功能及转化结构--以鄂尔多斯为例

近年来,我国干旱地区湖泊先后干涸,出现了严重的生态危机,其主要原因是对水资源的服务功能不明确而导致的不合理利用.本文将干旱地区水资源按其服务功能划分为生态水、资源水和景观水3种,按照不同服务功能的需求探讨了3种水资源的计算方法,并研究了在人类影响和自然变化下3种水资源相互之间可能产生的转化及其途径,为干旱地区水资源的合理利用提供参考依据.