High methane emissions from a littoral zone on the Qinghai-Tibetan Plateau

The littoral zones of lakes have been regarded as hotspots of methane (CH₄) fluxes through several studies. In the present study, we measured CH₄ fluxes in six kinds of littoral zones of Huahu Lake on the Qinghai-Tibetan Plateau in the peak growing season of 2006 and 2007. We found that CH₄ efflux (ranging from −0.1 to 90 mg CH₄ m⁻² h⁻¹) from the littoral zones of this lake was relatively high among those of boreal and temperate lakes. Our results also showed that emergent plant zones (Hippuris vulgaris and Glyceria maxima stands) recorded the highest CH₄ flux rate. The CH₄ flux in the floating mat zone of Carex muliensis was significantly lower than those of the emergent plant zones. CH₄ fluxes in the floating-leaved zone of Polygonum amphibium and bare lakeshore showed no significant difference and ranked last but one, only higher than that of the littoral meadow (Kobresia tibetica). Plant biomass and standing water depths were important factors to explain such spatial variations in CH₄ fluxes. No significant temporal variations in CH₄ fluxes were found due to the insignificant variations of physical factors in the peak growing season. These results may help in our understanding of the importance of the littoral zone of lakes, especially the emergent plant zone, as a hotspot of CH₄ emission.     

Water Resources of Central Asia and Adaptation Measures for Climate Change

A large part of the Central Asian region is located within the inner flow of the Aral Sea basin. The water resources are formed from renewed superficial and underground waters of natural origin, and also with returnable waters. The intensive increase of water intake, that took place in the second half of the twentieth century caused practically complete assimilation of the river inflow. That was the main reason for the Aral Sea crisis. On the basis of the analysis of long periodical rows of observation by meterological and hydrological stations, the estimation of regional water resources and calculations of changes of some components of the hydrological cycle due to the expected climate changes are presented. Measures for adaptation in the southern part of the Aral Sea region are considered.     

筑坝蓄水过程对高原湿地拉市海湖滨植被的影响

选择滇西北高原湿地拉市海湿地湖滨作为研究区域,采用传统的野外植被调查和定位观测相结合的方法对该区域植被特征、分布格局及受筑坝蓄水过程的影响进行分析和研究。结果表明：研究区共有维管束植物97种,隶属于34科76属,可划分为2个植被类型,3个植被亚型,10个群落类型;拉市海筑坝蓄水过程对研究区植物群落分布格局和组成结构产生明显的影响,草甸植被、沼泽植被和湖泊水生植被占研究区面积比重分别从2009年的4454%、1869%和3676%变为2011年的3259%、1368%和5359%,草甸植被和沼泽植被的面积不断缩小,湖泊水生植被面积持续扩大,狗牙根〖WTBX〗（Cynodon dactylon）逐渐取代蒿属（Artemisia）〖WTBZ〗植物在草甸植被中的优势地位,而李氏禾群落（Com.Leersia hexandra）成为了研究区湖滨带水生植物的主要成分;研究区植被在筑坝蓄水过程的胁迫下呈草甸植被（杂草群落、狗牙根群落Com.Cynodon dactylon）,沼泽植被（葱状灯心草群落Com.Juncus allioides、菖蒲群落Com.Acorus calamus、刚毛荸荠群落Com.Eleocharis vallcculosa、水蓼群落Com.Polygonum hydropiper）,湖泊水生植被（李氏禾群落Com.Leersia hexandra、两栖蓼群落Com.Polygonum amphibium、满江红群落Com.Azolla imbricata、鸭子草 穗状狐尾藻群落Com.Potamogeton distinctus Myriophyllum spicatum）的演替格局;拉市海植物群落受筑坝蓄水过程影响发生的逆向演替,从理论上延长了湿地的服务年限,但蓄水过程对鱼类的生存和繁殖、越冬水禽的生境及整个湿地生态系统结构和功能的影响是长期的,还有待深入的研究     

基于WRF模式的云南省干旱发生风险的预测分析

云南省作为西部大开发的典型省份之一,有着独特的自然环境和资源禀赋,但同时全省地形复杂多变且处于气候带的脆弱区,气候变率相当大.本研究在分析云南省近30年的土地利用/土地覆被变化的前提下,采用中尺度天气研究与预报Weather Researchand Forecasting (WRF)模式系统,对云南省未来40年干旱发生风险进行了预测分析.研究首先对WRF模式系统适用性进行了验证,重点分析了气温和降水两个主要干旱影响因子的未来时空变异特征.然后根据WRF模式系统的输出结果,选取了系列气象干旱指标因子,并采用综合气象干旱指数计算方法在空间和时间上对干旱发生风险进行了预测.从研究结果来看,加强对现用森林资源的保护,执行长期有效的生态工程建设,可以很大程度上减缓未来干旱发生频率.同时云南省当前“城市上山”等政策实施中也应考虑到建设用地扩张的不可逆转性,避免城市盲目上山.研究指出,未来区域发展规划应该对人为土地利用进行长期且合理有效部署,减少政策的不确定性,合理的区域发展规划是应对干旱风险的有效举措.     

气候变化对长江源地区高寒草甸生态系统的影响

近十几年来,长江源区气候暖干化趋势明显,冰川退缩、湖泊萎缩、草场退化、土地沙漠化、水土流失等环境问题日益严重。高寒草甸是长江源地区主要的植被类型之一,在全球变化影响下,以耐低温寒冷的嵩草属（Kobresia）植物为建群种的高寒草甸将面临更严重的生态胁迫。以长江源地区高寒草甸生态系统为研究对象,采用国际通用的生物地球化学模型模拟高寒草甸生物量、生产力和土壤有机质等的动态变化,并综合考虑人类活动对生态系统生产力和营养元素生物地球化学循环的影响,探讨了全球气候变化对高寒草甸生态系统可能造成的影响。     

Effect of Rainfall Regime and Slope on Runoff in a Gullied Loess Region on the Loess Plateau in China

Runoff was measured from seven plots with different slopes nested in Tuanshangou catchment on the Loess Plateau to study effect of slopes on runoff in relation to rainfall regimes. Based on nine years of field observation and K-mean clusters, 84 rainfall events were grouped into three rainfall regimes. Rainfall regime A is the group of events with strong rainfall intensity, high frequency, and short duration. Rainfall regime C consists of events with low intensity, long duration, and infrequent occurrence. Rainfall regime B is the aggregation of events of medium intensity and medium duration, and less frequent occurrence. The following results were found: (1) Different from traditional studies, runoff coefficient neither decreased nor increased, but presented peak value on the slope surfaces; (2) For individual plot, runoff coefficients induced by rainfall regime A were the highest, and those induced by rainfall regime C were the lowest; Downslope, the runoff coefficients induced by three rainfall regimes presented the same changing trend, although the peak value induced by regime A occurred on a shorter slope length compared to those by regime B and C; (3) Scale effect on runoff induced by rainfall regime A was the least, and that induced by rainfall regime C was the largest. These results can be explained by the interactions of crusting, soil moisture content, slope length and gradient, and erosion units, etc., in the context of different rainfall regimes.     

云南九大高原湖泊水体放射性状况调查研究

文章报道了2005年度分平水期和枯水期对云南省九大高原湖泊水体放射性状况进行的调查研究结果。本次行动初步调查清楚了2005年九湖核素浓度(U、Th、~(226)Ra、~(40)K)总α和总β值的区域最大值。调查结果表明,这九大高原湖泊水体的放射性核素浓度基本属正常本底水平,没有受到人工放射性的污染。     

滇中高原公路沿线植被特征分析及其恢复刍议——以昆明周边3条公路为例

选取滇中高原面上具有典型代表意义的3条公路,就其沿线的植被覆盖状况展开实地调查,对其主要植被类型进行分析,归纳得出滇中高原公路沿线植被基本特性,并对该地区有关公路沿线生态恢复建设提出浅显的认识与刍议,为促使云南高原山地公路沿线植被能尽可能地发挥其生态和社会经济功能提供思路。     

青藏高原冰川雪细菌与气候环境的关系

通过荧光显微镜测定细菌密度,利用DGGE图谱和Shannon-Weaver指数分析细菌种类多样性,对青藏高原北部老虎沟12号冰川、南部东绒布冰川和东南部海螺沟2号冰川雪坑的细菌密度和种类多样性做了差异性分析. 结果表明:老虎沟12号冰川雪坑细菌密度平均值比东绒布冰川和海螺沟2号冰川高,老虎沟12号冰川雪坑细菌种类多样性比东绒布冰川高,这与高原南、北部不同大气环流引起的大气微粒含量的差异性有关. 海螺沟2号冰川雪坑细菌种类多样性均最高,与该冰川所受的大气环流多样性最高相一致. 东绒布冰川雪坑细菌密度平均值与南极点相近,与其远离人类污染,因而大气环境本底值低有关. 海拔高的东绒布冰川雪坑细菌密度和种类多样性均比海拔低的海螺沟2号冰川和老虎沟12号冰川低,即二者与海拔高度呈反比.      

黄土高原半干旱区雨水利用与可持续农业发展研究

黄土高原半干旱区是一个特定的生态类型和重要的农业区域 ,严重的水土流失和频繁的干旱是该区农业可持续发展的主要制约因素。本文在分析雨水利用可行性的基础上 ,提出了农业发展的有效模式———集水型生态农业 ,它不仅适应于当地的雨水等自然资源条件 ,更适应生产力发展水平 ,易于在农户水平上推广 ,并且具有显著的经济、生态和社会效益 ,是实现该区农业可持续发展的战略性举措 ,同时也为“退耕还林 (草 )”开发战略的实施提供了一个思路