温带荒漠中温度和土壤水分对土壤呼吸的影响

荒漠对气候变化具有高度敏感性,深刻认识和量化非生物因子对荒漠生态系统土壤呼吸的影响具有重要意义。采用自动CO2通量系统(Li-8100)监测了梭梭(Haloxylon ammodendron)、假木贼(Anabasis aphylla)和盐穗木(Halostachys caspica)群落生长季土壤呼吸及温度、土壤含水量等,深入分析了水热因子对土壤呼吸的影响。土壤呼吸具有不对称的日格局,最小值出现在8:00,最大值在12:00～14:00。土壤呼吸的季节格局与气温变化基本同步,最小值在生长季末期(10月),最大值在生长季中期(6～7月)。梭梭、假木贼和盐穗木群落生长季平均土壤呼吸速率分别为0.76、0.52和0.46μmol CO2·m-2·s-1。气温对假木贼(51%)和盐穗木群落(65%)土壤呼吸季节变化的解释率高于梭梭(35%)。梭梭、假木贼和盐穗木群落土壤呼吸温度敏感性(Q10)逐渐增大,基础呼吸速率(R10)逐渐减小。剔除温度影响后,梭梭、假木贼群落土壤呼吸与土壤含水量呈显著的幂二次方函数关系,盐穗木群落两者关系却明显减弱,未达到显著水平。气温、土壤含水量的二元方程均能解释群落土壤呼吸大部分的时间变异:梭梭群落71%～93%、假木贼群落79%～82%、盐穗木群落70%～80%。人工模拟降水后土壤呼吸速率表现出降水后10min减小、180min时明显增加、达到最大值后再次衰减的现象。5和2.5mm降水处理下的土壤呼吸速率最大值和其后的递减值高于对照处理,土壤呼吸增加、达到峰值和其后递减过程与5cm土壤温度变化基本同步

Research on the Land Use

近几十年来，随着人口的急剧增长和科学技术水平的提高，人类的活动以空前的速度、幅度和空间规模改变着陆地环境，促使土地利用/覆被格局产生了深刻变化，由此引发了一系列环境问题。塔里木河干流区地处我国干旱少雨的西部地区，人类活动的不断加剧及水土资源的无序过度开发和低效利用，使得干流区的整体生态环境十分恶劣，己成为制约绿洲生态稳定和社会经济可持续发展的主要障碍，并直接影响到我国西部开发的战略问题。本研究以塔里木河干流区为研究对象，在遥感和GIS技术的支持下，应用地理学、景观生态学、统计学、数学等学科的理论和方法，研究塔里木河干流区土地利用/覆被空间动态变化过程及景观格局的响应，揭示土地利用格局演变的机制和规律，探讨驱动土地利用变化的主要因素和驱动机制，并在此基础上，对该区土地利用/覆被变化的生态环境效应进行分析，最后提出塔里木河干流区水土资源可持续利用的对策和措施。主要研究结论如下： 1、在过去的30多年里，塔里木河干流区的土地利用/覆被发生了显著的变化，表现为耕地和居工地的大幅度扩张，并伴随着林地、草地和湿地的大面积丧失和未利用地的增加；近15年塔里木河干流区的土地利用程度不断加大，特别是2000~2005年更是明显；土地利用的变化速度经历了一个显著变化-缓慢变化-显著变化-急剧变化的U字型变化过程。在空间变化上，耕地、林地、草地和湿地的重心由下游向上中游方向移动，而居工地和未利用地的重心则由上游向中游方向移动。 2、塔里木河干流区的景观格局也发生了显著的变化，在斑块类型水平上，耕地和居工地景观比例持续增加，斑块连片分布，林地、草地和湿地的景观比例减少，破碎化程度加大，未利用地景观比例总体上增加，斑块形状简单化和破碎化；在景观水平上，景观多样性和景观均匀度增加，景观优势度降低，景观破碎度增大，优势景观类型草地和未利用地对整个景观的控制作用降低，景观破碎化程度加大。 3、塔里木河干流区海拔高度、坡度、地貌、土壤条件、水源状况和气候条件等自然因素对于土地利用/覆被格局的形成具有决定性的作用，在长时间尺度上控制着土地利用/覆被变化的方向和趋势。但在短时期内，除地貌和距河道距离对土地利用/覆被变化有一定的影响外，其他自然因素对干流区土地利用/覆被变化的影响较小。在地势较为平坦且距离河道较近的河漫滩和平原区，土地利用/覆被变化较为剧烈，而且变化首先在这些区域开始，随着可开垦土地资源的短缺，土地利用变化开始向地貌较为复杂且距离河道较远的区域发展。驱动干流区土地利用/覆被变化的主要因子是人口及经济发展因素、产业结构和政策因素及人类干扰强度，其中，人口增长和经济发展因素是塔里木河干流土地利用/覆被变化的最直接驱动力。 4、塔里木河干流区土地利用/覆被变化的生态环境效应主要表现为，①耕地和居工地等人工景观所占的比例增加，部分地区的自然景观被人工景观所取代，同时，景观多样性和破碎度逐渐增加，优势度逐渐降低，空间异质性增加，景观的边缘效应显著；②下游来水量减小，地下水位下降，水质沿程逐年恶化，同时改变了水量的年内分配，造成冬季和春季严重缺水；③土地利用/覆被变化改变了土壤的理化性质，一方面，土地的开垦和耕作降低了土壤盐分，另一方面，土地退化造成土壤容重增加，养分下降，有机质含量下降，碱性明显增强；④另外，土地利用/覆被变化引起荒漠河岸林减少，草场退化，土壤盐渍化和土地荒漠化加剧，湿地面积锐减，生物多样性降低，生态环境恶化。 5、提出塔里木河干流区水土资源可持续发展的对策与建议为：①控制人口数量，减轻环境压力；②加强水土资源调控手段和规划管理，落实土地资源可持续利用政策；③以保护策略为主，逐步恢复和重建受损的生态系统；④加强生态用地保护，建立环境友好型水土资源利用模式；⑤加强生态环境投入，切实实施生态环境保护和建设；⑥大力宣传环境保护和可持续发展，共同保护生存环境。该研究不仅可以为塔里木河干流区受损生态系统的恢复和水土资源可持续利用提供理论参考，而且对改善区域生态环境、维护社会稳定、保障国家安全、实现西部大开发宏伟战略目标具有重大的现实意义。In the last few decades, human activities have been altering the terrestrial environment by unprecedented speed, amplitude and spatial scale. The land use/cover changed profoundly, which induced a series of environmental problems. The main stream of Tarim River is located in the arid inland with the rare rainfall in the western area of China, where extremely fragile ecological environment resulted from the increasing human activities and the excessive disorder development and ineffective utilization of the soil and water resources. The abominable eco-environment has been a barrier to keep the oasis ecosystem stable and the local socio-economic developments sustainable, and directly affects the strategies of great exploitation in western China. Taking the main stream of Tarim River as research object, through remote sensing and GIS technology, based on the theories and methods of geography, landscape ecology, statistics and mathematics, the temporal and spatial changes of land use/cover and response of landscape pattern were analyzed, and the mechanism and laws of the evolution of land-use pattern were revealed in this paper. Driving forces and mechanisms that lead to changing of land use/cover pattern was also analyzed. Through above analysis, the eco-environmental effects of LUCC in study area were appraised synthetically. At last, this paper provides some measures and suggestions on water and soil resources development and utilization. The main conclusions are as summarized as: Firstly, there had been a great change of land use/cover in the main stream of Tarim River during the past 30 years. The areas of farmland and residential land increased obviously, areas of grassland, forest and wetland decreased, and that of unused land increased first then decreased. The major patterns of land use change were the conversions of grassland, forest and wetland to farmland, farmland to residential land, and grassland to unused land. The integrated index of land use increased continuously during the past fifteen years, especially from 2000 to 2005. Land use change rate underwent a process of ‘U’ shape with ‘obvious change - slow change - obvious change - tremendous change’. As to the spatial distribution, the centroids of farmland, forest, grassland and wetland had a migration tendency from downstream to upstream and middle stream, meanwhile, the centroid of residential land and unused land had a tendency from upstream to middle stream migration. Secondly, the landscape pattern had also greatly changed during the past 30 years in the main stream of Tarim River. At class level, the percentage of landscape of farmland and residential land increased continuously with the characteristics of concentrated distribution, meanwhile, the percentage of landscape of forest, grassland and wetland had reduced with a fragmentation trend, and the percentage of landscape of unused land had increased as a whole with a fragmentation and simple trend. At landscape level, landscape diversity index increased while landscape dominance index decreased. Simultaneously, landscape fragmentation index increased gradually. The control function of grassland and unused land to landscape declined, and the diversification and evenness of landscape pattern were more obvious. Thirdly, the natural factors, such as, altitude, slope, geomorphology, soil conditions, water conditions and climatic conditions, play a decisive role and control directions and trends of land use/cover change in the long time scale. However, in a short period of time, in addition to topography and distance from the river which had some influences on land use/cover change, other natural factors had less effect on land use/cover change in the main stream of the Tarim River. In relatively flat floodplain and plain where close to the river, land use/cover changed firstly and more rapidly. As the shortage of cultivated land resources, land use/cover change occurred at the areas with more complex topography and farther distance from the river. Driving factors of land use/cover change are population growth and economic development, the industrial structure and policy, and human disturbance intensity, in which population growth and economic development are most direct driving force in the main stream of Tarim River Fourthly, the main eco-environmental effects by land use/cover change in the mainstream of Tarim River were as following: 1) the percentage of the artificial landscape such as farmland and residential land increased, and some areas of the natural landscape had been replaced by artificial landscape. At the same time, landscape diversity, fragmentation and spatial heterogeneity increased while landscape dominance decreased gradually, and landscape edge effect was more significant. 2) Caused the decrease of water resources in downstream, decline of water table, deterioration of water quality along the way in year-on-year, but also changed the distribution of water during the year, resulting in severe shortage in winter and spring. 3)land use/cover change had transformed the soil physicochemical properties. On the one hand, land reclamation and farming reduced soil salinity; on the other hand, land degradation caused increase of soil bulk density, decline of nutrient and organic matter content and significant enhancement of alkaline. 4) Caused the reduction of riparian forest, grassland degradation, soil salinization, land desertification, wetlands area reduction, biodiversity decrease, and ecological deterioration of the environment. At last, measures and suggestions are put forward as following: 1)control population quantity to reduce the pressure on the environment; 2) strengthen the regulation and planning management of land and water resources and implement the policy of sustainable utilization of land resources; 3)recover and reconstruct damaged systems through protective measures; 4)strengthen ecological land protection, and set up a mode with environment-friendly utilization of water and land resources; 5)strengthen ecological environment inputs, and implement ecological environment protection and construction effectively; 6) vigorously promote environmental protection and sustainable development to protect environment jointly. The study not only can provide theoretical basis for restoring damaged systems and achieving sustainable development of the regional in the main stream of Tarim River, but also have profound significance of theory and practice to improve the regional ecological environment, safeguarding social stability, protect national security, and implement West China Development Drive

干旱区内陆河流域的生态需水量研究与估算 ——兼谈塔里木河生态需水量问题

塔里木河流域综合治理是以水资源合理分配和有效利用为核心的，旨在通过保护上游、治理中游来达到恢复下游生态系统的目的。从塔里木河流域综合治理的行为过程来看，上游重点是山地水源涵养区的生态保育问题，中游涉及的是河道生态工程治理问题，而下游则主要是在生态输水条件下以自然生态恢复过程为主的合理生态水位、生态需水量和生态系统安全等问题。本文结合对干早区生态安全和生态需水量关键科学问题的探讨、实证分析以及维系塔里木河生态安全的生态需水量计算，为塔里木河流域的生态整治和社会经济可持续发展提供科学依据

古尔班通古特沙漠南缘主要土壤化学特征的空间异质性

运用半方差分析和Kriging插值研究了古尔班通古特沙漠南缘典型沙垄至垄间地浅层土壤(0～30cm)pH值、电导率、有机质及全N含量的空间变异特征。结果表明,土壤pH值、有机质及全N含量服从正态分布,电导率符合对数正态分布。半方差分析结果显示,土壤pH值、电导率符合球状模型,而有机质、全N含量符合高斯模型。除全N具有中等空间相关性外,其余的都具有强空间相关性。用Kriging插值法对未测点的参数含量进行最优估计,绘制含量分布图,从而更直观地反映研究区土壤参数空间变异特征

干旱荒漠区不同土地利用/覆盖类型土壤呼吸速率的季节变化

结合生长季对准噶尔盆地新垦绿洲外围人工防护林(杨树林)和天然荒漠(柽柳+芦苇群落、梭梭群落)土壤呼吸速率及主要环境因子的测定,分析了不同土地利用/覆盖类型间土壤呼吸速率的差异性和土壤呼吸对温度、土壤含水量变化的响应.结果表明:土壤CO2释放速率随温度逐渐升高,杨树林、柽柳+芦苇群落和梭梭群落的最高值分别出现在18:00,12:00和14:00,最低值皆出现在早晨8:00.5～10月,土壤呼吸速率呈现增加而又降低的趋势,主要与近地面气温的变化一致,在6～7月达到最大值,8月下降.生长季,平均土壤CO2释放速率、季节变化幅度按大小顺序排序为:杨树林>柽柳+芦苇群落>梭梭群落,不同土地利用/覆盖类型间土壤呼吸速率的差异均很显著.杨树林土壤呼吸速率与近地表气温、土壤10cm温度间存在显著的指数函数关系(P<0.01),柽柳+芦苇群落和梭梭群落与近地面气温、地表温度间的线性相关显著(P<0.01).基于近地面气温,计算得出Q10值分别为1.48,1.59,1.63.3种土地利用/覆盖类型的土壤呼吸速率(综合)与0～5,5～15和0～15cm的土壤含水量呈极显著和显著的正相关关系(P<0.01).0～5cm土壤含水量与土壤呼吸速率间呈显著的二项式函数关系(P<0.01)

塔里木河中下游湿地及周边植物群落与环境因子的关系初探

选取塔里木河中下游湿地及周边16个典型植物群落样地调查和环境因子数据,采用主分量分析(PCA)排序技术和回归分析,定量分析湿地及周边植物群落在空间上的分布格局,以及群落结构特征和环境梯度之间的关系.结果表明,影响塔里木河中下游湿地及周边植物群落分布的第1主分量中,土壤水分和盐分影响最大,贡献率为35·70%;在第2主分量中,土壤养分的影响最大,贡献率为25·97%.植物群落分布的生境可分为沼生轻盐中营养生境、湿生中盐中营养生境、中生中盐低营养生境和中旱生重盐低营养生境4种类型.沿不同生境依次分布着沼泽植被、草甸植被、河岸疏林和盐生荒漠-盐化灌丛植被.塔里木河中下游湿地及周边植物群落的生态优势度与土壤水分和盐分复合梯度呈显著的一元线性相关.二元回归分析结果显示,塔里木河中下游湿地及周边土壤水分和盐分复合梯度与多样性指数和生态优势度二元指标呈极显著相关

塔里木河中下游湿地及其周边土壤粒度的空间分布

塔里木河中下游湿地及其周边土壤粒度组成、粒度参数及分维值的分析计算结果表明：其土壤粒度多为以粗粉沙-极细沙-细沙为主的颗粒组成，是沙质或粉沙质壤土；少数以粘粒-极细粉沙-细粉沙为主要成分，属壤质沙土或粉沙土。发育不同植被类型湿地及周边土壤剖面质地垂向变化及粒度参数φ1、Mz和σ值存在差异，反映了不同土地类型和植被类型及盖度对土壤粒度特征的影响。研究样地土壤粒度分维值总体上的相近和类型间分维值变异系数的差异，进一步显示出这些土壤的成土来源和沉积过程的不同