西南地区近14a植被覆盖变化及其与气候因子的关系

基于1999~2012年NDVI数据,结合气温和降水资料,运用GIS和RS技术,分析了西南地区近14a植被覆盖的时空变化特征及与气温、降水的关系。结果表明:(1)该区植被生长良好,各植被类型NDVI均呈显著增加趋势。空间整体表现为改善状态,改善面积远大于退化面积,严重退化区仅占1.18%。退化区分布于横断山地北部、四川盆地东部以及云贵高原中部。(2)植被覆盖变化将以良性发展为主,但强持续性的退化区和弱持续性的改善区应值得关注;强持续性的退化区主要分布在横断山地中北部、云贵高原中西部、若尔盖高原中部、四川盆地与若尔盖高原相交区域;草原强持续性的退化面积最大,针阔混交林强持续性的改善面积最大。(3)NDVI与温度存在明显的正相关关系,而与降水及干旱指数变化的关系不太明显,温度是影响该区植被变化的主要自然因素。     

基于变更平衡表的土地利用演化信息提取与预测方法研究——以苏州市为例

变更平衡表为国土资源管理部门历年实地调查、汇总所得,精度高,目前的研究中对其深入的应用较少,基于变更平衡表的应用方法研究可为区域土地利用演变信息提取与预测提供帮助。推导了由连续年份的年度变更平衡表求多年周期的平衡表的方法,提出了基于土地利用综合动态度分析土地利用有序程度的思路,探讨了利用连续年份的变更平衡表预测任意年份土地利用结构的方法,并基于传统方法进行了改进,提出了利用矩阵开方法求预测概率矩阵。应用苏州市一定时期的连续年份的年度变更平衡表对上述方法进行了验证,结果表明:提出的信息提取方法有效,预测结果可信;在分析期内(1998~2008年),苏州市耕地大量减少的去向是各类建设用地增加的来源,区域土地利用有序程度较高;预测显示至2020年土地利用结构变化仍将维持农用地、耕地不断减少和建设用地总量不断增加的趋势,但转化的速率将有所放缓;对变更平衡表的深入应用有一定的借鉴意义。     

安徽省土地利用变化下的生态敏感性时空规律

土地利用变化过程中生态敏感性的研究有利于土地利用的科学管理和健康长效的城市化发展。选择安徽省为研究区域,通过分析土地利用变化对生态系统的敏感性的影响机制,构建出基于弹性概念的生态敏感性指数模型,并利用2002~2011年安徽省的土地利用变更数据,对其10年的生态敏感性的时空变化规律进行研究。结果表明:(1)2002~2011年,安徽省土地利用综合强度由2.26增加到2.49,生态服务价值由2.84×10¹²元减少到2.75×10¹²元,两者呈现出很强的负相关,且安徽省17个地级市的土地利用综合强度与生态服务价值也均呈现负相关关系;(2)安徽省土地利用变化下的生态敏感性指数由2003年的2.26上升到2011年的2.49,在研究期内均属于低敏感性,表明安徽省整个生态系统受其土地利用变化的影响程度不是很强烈,能够适应目前城市化发展的速度和强度;(3)安徽省由2003年的16个生态系统低敏感或不敏感市(占全省总面积的92.97%)减少到2011年的12个低敏感市(占全省总面积的67.06%),表明人类活动对生态系统已经造成了一定的影响。     

卫星遥感洞庭湖主汛期水体时空变化特征及影响因子分析

基于1989~2011年的长时间序列卫星遥感数据,利用综合水体信息提取方法提取了洞庭湖区6~9月主汛期的水体信息,通过较高分辨率卫星遥感数据验证,水体面积提取精度达到90%以上。洞庭湖年平均径流入湖量、NCEP再分析资料计算的湖体上空和流域累计月平均降水量分别与水体面积变化的关系进行分析,结果表明: 1989~2011年间洞庭湖水体面积最大值主要分布在7和8月,这两个月也是洞庭湖区域发生洪涝灾情的高风险期;洞庭湖水体面积与年平均径流入湖水量的相关系数为0.67(置信度为95%);2003年以前,洞庭湖主汛期间水体面积波动比较大,2003年三峡水库运行后,洞庭湖的面积波动有所减少;洞庭湖上空累计月平均降水量对于水体面积存在正相关性,相关系数为0.68(置信度为99%);2003年以前,洞庭湖流域累计月平均降水量和水体面积相关系数为0.50(置信度为90%),2003年三峡水库运行后,两者相关性有所减弱。     

An in-depth view of climate change:addressing climate change while making a transition on the development mode

While fossil fuels greatly contribute to human society,they pose great challenges to natural resources,the environment,and climate change.Developed countries,like the United States,formulated strategic measures to ensure their sustainable development and leading positions in the world.These measures include new green policies,development of shale gas,revitalization of nuclear power,energy independence,reindustrialization,and new low-carbon development based on a combination of Internet technology and renewable energy.Developing countries are also trying to introduce balanced strategies of poverty alleviation and sustainable development.Globally,industrial civilization is being transformed to ecological civilization and green,low-carbon development is a global trend.Addressing climate change provides new strategic factors to further this development.China should take substantial actions to realize sustainable development in a new road:China is in the critical stage of changing its development mode,so it is vital to choose an appropriate development path.This extensive development comes at the high price of consuming too much resources and scarring the environment.Mitigation and adaptation strategies for addressing climate change can help the transition of development.Based on the analysis of the development data of developed countries,the author introduces the concept of"two-type developed countries"with an understanding that not all developed countries must take the same development mode.He also holds the view that China should achieve modernization in a more energy-saving and more carbon-efficient manner compared with that of two-type developed countries.An analysis of"two competitions"that China is facing shows that changing the developing mode is urgent and China should grasp this opportunity in the next five to ten years,which is a key period for this transition.This paper discusses the low-carbon development goals and the three-step process.Low-carbon development does not necessarily restrict economic development.It,however,can expedite the transition of the development mode and this is a low-carbon and green development path.Transition of the development mode includes implementation of China’s green and low-carbon energy strategies,low-carbon society construction,development of agriculture and forestry,garbage sorting and utilization,innovation of urbanization,etc.Improvement of national infrastructure construction includes water safety,environment and climate monitoring system,intelligent energy web,basic database,etc.Addressing climate change can significantly improve the nation’s basic research level.In summary,it mitigates backward production capability,extensive development,and environmental damage while promoting technological advancement,scientific development,and ecological civilization.     

Structure and Content of the Discourse on Climate Change in the Blogosphere: The Big Picture

Based on the texts of 1.3 million blog posts and the structure of the links between the blogs in which these posts appeared, this study presents an analysis of the discourse on climate change in the English-language blogosphere. Our approach combines community detection with probabilistic topic modeling to show how topics related to climate change are discussed across various parts of the blogosphere. We find that there is one community of predominantly climate skeptical blogs but several accepter communities. The topic analysis reveals a series of issues that are characteristic of the climate change discourse in the blogosphere. Two topics, one related to climate change science and one related to climate change politics, are particularly important for characterizing the discourse. We also find that the distribution of topics over the communities cuts across the divide between skeptics and non-skeptics (accepters) and that there are differences in the patterns of interactions between the skeptics and different groups of accepters.     

Models-as-usual for unusual risks? On the value of catastrophic climate change

We study the role of intertemporal preference representations in a model of economic growth, stock pollutant and endogenous risk of catastrophic collapse. We contrast two polar instances of risk-sensitive preferences: the traditional “discounted utility” model, which imposes a positive rate of pure time preference and risk neutrality with respect to intertemporal utility, and multiplicatively separable preferences, which display risk aversion in that dimension but no pure time preferences. We show that both representations of preferences can rationalize the same economy when there is no collapse risk associated with pollution. Once we introduce a collapse risk whose hazard rate depends on the pollution stock, multiplicatively separable preferences are associated with a much higher value of catastrophic risk reduction, and a more stringent policy response. A relatively high discount rate may thus be compatible with large emissions abatement in the face of a low probability large impact event, reflecting preferences for catastrophic risk reduction.     

The integrated project AquaTerra of the EU sixth framework lays foundations for better understanding of river-sediment-soil-groundwater systems

The integrated project "AquaTerra" with the full title "integrated modeling of the river-sediment-soil-groundwater system; advanced tools for the management of catchment areas and river basins in the context of global change" is among the first environmental projects within the sixth Framework Program of the European Union. Commencing in June 2004, it brought together a multidisciplinary team of 45 partner organizations from 12 EU countries, Romania, Switzerland, Serbia and Montenegro. AquaTerra is an ambitious project with the primary objective of laying the foundations for a better understanding of the behavior of environmental pollutants and their fluxes in the soil-sediment-water system with respect to climate and land use changes. The project performs research as well as modeling on river-sediment-soil-groundwater systems through quantification of deposition, sorption and turnover rates and the development of numerical models to reveal fluxes and trends in soil and sediment functioning. Scales ranging from the laboratory to river basins are addressed with the potential to provide improved river basin management, enhanced soil and groundwater monitoring as well as the early identification and forecasting of impacts on water quantity and quality. Study areas are the catchments of the Ebro, Meuse, Elbe and Danube Rivers and the Brévilles Spring. Here we outline the general structure of the project and the activities conducted within eleven existing sub-projects of AquaTerra.     

农业土地利用转变对土壤团聚体组成及碳、氮含量的影响

为探究农业土地利用转变对土壤团聚体组成、稳定性及有机碳（SOC）、全氮（TN）含量变化的影响,选取玉米地、玉米地转变为姜地、稻田和稻田转变为姜地4种农业土地利用类型为研究对象,对土壤水稳性团聚体的组成、稳定性及SOC、TN含量进行测定与分析.结果表明： ①玉米地转变为姜地后,>0.25 mm粒级的大团聚体减少21.48%（p<0.01）,>0.25 mm稳定性团聚体的含量（DR_0.25）显著降低53.39%;稻田转变为姜地后,大团聚体差异不显著,<0.053 mm粒级的粉黏团聚体增加8.93%（p<0.01）;冗余分析和相关分析表明,土壤含水量是团聚体组成和 稳定性的重要影响因素;②玉米地转变为姜地后,0.25~1 mm粒级团聚体中SOC、TN含量分别减少52.68%、50.98%,粉黏团聚体（<0.053 mm）中SOC和TN含量增加约2倍（p<0.01）;稻田转变为姜地后,>0.25 mm的大团聚体和0.053~0.25 mm的微团聚体中的SOC、TN含量均减少（p<0.05）,其中,大团聚体碳氮比与团聚体组成和稳定性存在相关关系（p<0.05）;③所有处理均为大团聚体SOC、TN贡献率最高,转变后的姜地较玉米地、稻田的土壤粉黏团聚体的SOC、TN贡献率显著增加,尤其是较玉米地的粉黏团聚体SOC、TN贡献率增加3倍（p<0.01）;④平均质量 直径（MWD）和几何平均直径（GMD）与大团聚体的SOC、TN含量呈显著正相关（p<0.05）,分形维数（D）与MWD及1~2 mm粒级大团聚体的SOC、TN含量呈显著负相关（p<0.01）,DR_0.25与大团聚体的SOC、TN含量呈显著正相关（p<0.01）.总体上,玉米地和稻田两种用地转变为姜地后,土壤团聚体的组成发生较大变化,团聚体稳定性变化虽不显著,但大团聚体中SOC、TN含量降低,粉黏团聚体中SOC、TN含量增加.本研究的开展对农田科学管理和可持续生产具有重要的指导意义.     

基于InVEST-PLUS模型的碳储量空间关联性及预测——以广东省为例

构建土地利用碳储量数据库,基于InVEST模型Carbon模块,得到广东省1990~2020年碳储量时空分布情况.用Moran’s I指数和Getis-Ord Gi^*分析格网尺度下碳储量时空分布特征,用Anselin Local Moran’s I得到LISA集聚图.然后运用PLUS模型和14个土地利用驱动因子预测2050年土地利用及其碳储量分布.结果表明,土地利用变化直接影响区域碳储量高低,林地、草地等具有生态服务功能地类碳密度最高,分别是188.44,329.34Mg/hm².碳储量空间格局整体呈现出中部低、北部高、东西中等的特点.碳储量空间分布特征与土地利用特征一致,碳储量显著高值集聚区域分布在建设用地少、生态用地多且连片的粤北地区,显著低值区域分布在国土开发强度和生态用地破碎化程度高的珠三角地带.在自然发展情景下,到2050年广东省土地利用碳储量将减少4327.21万Mg,随着国土空间进一步开发,环珠江口沿岸城市碳储量持续下降.增加植被生态系统碳储量,是实现碳中和的重要手段之一.要继续维持粤北山区生态保护屏障的重要地位,减缓珠三角城市土地开发强度,提高建设用地集约节约能力,形成平衡协调的土地利用和碳储量格局.