Conservation Threats Due to Human-Caused Increases in Fire Frequency in Mediterranean-Climate Ecosystems

Periodic wildfire is an important natural process in Mediterranean-climate ecosystems, but increasing fire recurrence threatens the fragile ecology of these regions. Because most fires are human-caused, we investigated how human population patterns affect fire frequency. Prior research in California suggests the relationship between population density and fire frequency is not linear. There are few human ignitions in areas with low population density, so fire frequency is low. As population density increases, human ignitions and fire frequency also increase, but beyond a density threshold, the relationship becomes negative as fuels become sparser and fire suppression resources are concentrated. We tested whether this hypothesis also applies to the other Mediterranean-climate ecosystems of the world. We used global satellite databases of population, fire activity, and land cover to evaluate the spatial relationship between humans and fire in the world's five Mediterranean-climate ecosystems. Both the mean and median population densities were consistently and substantially higher in areas with than without fire, but fire again peaked at intermediate population densities, which suggests that the spatial relationship is complex and nonlinear. Some land-cover types burned more frequently than expected, but no systematic differences were observed across the five regions. The consistent association between higher population densities and fire suggests that regardless of differences between land-cover types, natural fire regimes, or overall population, the presence of people in Mediterranean-climate regions strongly affects the frequency of fires; thus, population growth in areas now sparsely settled presents a conservation concern. Considering the sensitivity of plant species to repeated burning and the global conservation significance of Mediterranean-climate ecosystems, conservation planning needs to consider the human influence on fire frequency. Fine-scale spatial analysis of relationships between people and fire may help identify areas where increases in fire frequency will threaten ecologically valuable areas.     

Combining a generic process-based productivity model and a statistical classification method to predict the presence and absence of tree species in the Pacific Northwest,U.S.A.

Although long-lived tree species experience considerable environmental variation over their life spans, their geographical distributions reflect sensitivity mainly to mean monthly climatic conditions. We introduce an approach that incorporates a physiologically based growth model to illustrate how a half-dozen tree species differ in their responses to monthly variation in four climatic-related variables: water availability, deviations from an optimum temperature, atmospheric humidity deficits, and the frequency of frost. Rather than use climatic data directly to correlate with a species’ distribution, we assess the relative constraints of each of the four variables as they affect predicted monthly photosynthesis for Douglas-fir, the most widely distributed species in the region. We apply an automated regression-tree analysis to create a suite of rules, which differentially rank the relative importance of the four climatic modifiers for each species, and provide a basis for predicting a species’ presence or absence on 3737 uniformly distributed U.S. Forest Services’ Forest Inventory and Analysis (FIA) field survey plots. Results of this generalized rule-based approach were encouraging, with weighted accuracy, which combines the correct prediction of both presence and absence on FIA survey plots, averaging 87%. A wider sampling of climatic conditions throughout the full range of a species’ distribution should improve the basis for creating rules and the possibility of predicting future shifts in the geographic distribution of species.     

Decadal changes in a NW Mediterranean Sea food web in relation to fishing exploitation

We analysed changes in the ecological roles of species, trophic structure and ecosystem functioning using four standardized mass-balance models of the South Catalan Sea (North-western Mediterranean). Models represented the ecosystem during the late 1970s, mid 1990s, early 2000s, and a simulated no-fishing scenario. The underlying hypothesis was that ecosystem models should quantitatively capture the increasing exploitation in the ecosystem from the 1970s to 2000s, as well as differences between the exploited and non-exploited scenarios. Biomass showed a general decrease, while there was an increase in biomass at lower trophic levels (TL) from the 1970s to 2000s. The efficiency of energy transfer (TE) from lower to higher TLs significantly increased with time. The ecosystem during the 1990s showed higher biomass and flows than during the 1970s and 2000s due to an increase in small pelagic fish biomass (especially sardines). Exploited food webs also showed similarities in terms of general structure and functioning due to high intensity of fishing already in the 1970s. This intensity was highlighted with low trophic levels in the catch, high consumption of production by fisheries, medium to high primary production required to sustain the catches and high losses in secondary production due to fishing. Significant differences on ecosystem structure and functioning were highlighted between the exploited and no-fishing scenarios. Biomass of higher TLs increased under the no-fishing scenario and the mean trophic level of the community and the fish/invertebrate biomass ratios were substantially lower in exploited food webs. The efficiency of energy transfer (TE) from lower to higher TLs was lower under the no-fishing scenario, and it showed a continuous decrease with increasing TL. Marine mammals, large hake, anglerfish and large pelagic fish were identified as keystone species of the ecosystem when there was no fishing, while their ecological importance notably decreased under the exploited periods. On the contrary, the importance of small-sized organisms such as benthic invertebrates and small pelagic fish was higher in exploited food webs.     

农业合作生产对华北农牧交错区水资源存量和经济效益的影响

针对华北农牧交错区错季蔬菜生产对水资源消耗的争议,通过试验和调查研究相结合的方法,研究了农业“生产－消费”合作生产背景下区域发展错季蔬菜的耗水效果及其对农民收入、水资源存量的影响。结果表明,错季蔬菜生产田间耗水量为农区粮食作物的31.3%~93.3%,而水资源价值为农区粮食作物的4.2~10.7倍;与区域内粮油作物生产相比,错季蔬菜生产少耗水330~754m³/hm²,且其水资源价值为粮油作物的4.0~13.9倍。通过实施粮－菜交换的市场农业战略,区域能用0.175~0.196m³的水交易获得外区域1 m³的水资源,并且实现了研究区用0.93hm²的菜地解决发展错季蔬菜前需要6.9~13.8hm²耕地才能解决的粮食问题。调查表明,通过高效地输出水资源,区域农民收入仅蔬菜一项比全国同期农村人均收入高出了23%。故华北农牧交错区发展错季蔬菜生产是节约和扩大本区域的水资源存量,促进农村脱贫致富、自我发展的有效途径。     

The regional economic impact of reducing greenhouse gas emissions: Western Australia

This study analyses the general-equilibrium impacts of an international climate change response policy on the economy of Western Australia (WA), one of the most mining-based and energy-intensive states of Australia. It finds that emissions would fall by up to 11% from the base level in WA. However, such environmental benefits emanate at some costs to the state economy; in terms of foregone gross state product, the costs are up to 3% of the base level. Indeed, the actual costs and benefits depend on the precise design of the climate change response policy as well as on the other policies within which it operates. For example, when emission quota permits are sold to industries and no tradeable carbon credits (i.e. credits for the carbon sequestrated in Kyoto forests) are granted, emissions decline by about 8% and GSP falls by about 3% of the base levels. If carbon credits are tradeable, however, the environmental benefits could be increased and the GSP cost could be reduced substantially. Also, the reduced economic activity caused by emission abatement results in a modest fall in net government revenue, despite the additional revenue from permit sales in some cases. Accordingly, government’s fiscal package surrounding the emission permits would influence the emission abatement impacts on the economy. With regard to the effects on the structure of the state economy, the oil and gas industry suffers only a slight contraction but the energy-supplying sector as a whole contracts substantially. It is therefore not surprising that the impacts on the WA economy of curbing emissions by energy and transport industries alone are quite significant when compared to those resulted from all industries’ compliance with the abatement scheme. It needs to be noted that the model projections analysed in the paper are based on simplifying assumptions and tentative scenarios, and hence should be viewed with caution and not be understood as unconditional forecasts.     

西部大开发与重庆市旅游业的可持续发展

重庆具有发展旅游业得天独厚的区位条件,而西部大开发进一步从交通环境、经济基础、市场开拓和生态保护几个方面为重庆旅游提供了良好的外部条件;但目前重庆的旅游业发展面临着严重的挑战。从战略方向和形象策划、客源定位、旅游产品的深层次开发、旅游基础设施的建设和旅游服务体系的完善、旅游管理和旅游人才的教育以及发展生态旅游几个方面,提出了重庆旅游业可持续发展的战略方向和战略对策。     

华北地区气溶胶数浓度和尺度分布的航测研究 ——以石家庄为例

2009年秋季利用河北省人工影响天气办公室机载气溶胶粒子探头(PCASP-100X)和前向散射滴谱探头(FSSP-100-ER)在石家庄市上空进行了多次气溶胶观测.选取2009年9~10月间的7架次雾天、1架次小雨天及1架次密卷云天观测资料,重点研究雾天气溶胶粒子数浓度和直径的垂直、水平分布特征及粒子谱分布,并与密卷云天和小雨天的探测资料进行对比分析.结果表明:石家庄地区气溶胶粒子数浓度较高,近地面最大值达11910个/cm3.气溶胶粒子数浓度主要受天气条件影响,逆温层是影响粒子垂直输送的主要因素,在逆温层下粒子累积形成粒子数浓度的高值区,逆温层以上气溶胶粒子数浓度迅速减少,雾天和密卷云天粒子数浓度随高度多呈负指数分布;雾天多伴有逆温层和较大空气湿度,有利于气溶胶粒子累积,数浓度一般可达104个/cm3以上,容易形成低能见度污染天气;气溶胶粒子数浓度在无降水日有累积效应,降雨对气溶胶粒子有明显清除作用;粒子数浓度和粒子直径在水平方向上呈不均匀分布,随着高度增加粒子数浓度和直径的水平绝对偏差减小,相对偏差往往增大;不同天气下尺度谱型类似,多呈单峰分布,在0.11μm左右处出现峰值,但在雾天、密卷云天、小雨天气下的气溶胶粒子峰值依次变小,并且随高度增加,尺度谱峰值数密度值降低,谱变窄.     

“Protecting coastal zones in the Mediterranean: an economic and regulatory analysis”

This paper examines existing measures taken to protect the coastal zones of the Mediterranean Sea and assesses their success. A summary of the main pressures facing this region is given, followed by an analysis of the legislation covering coastal zone development in ten countries: Algeria, Croatia, Egypt, France, Israel, Italy, Malta, Spain, Tunisia and Turkey. The paper finds that not all of these States have legislation specifically covering coastal zones, but there is concern in all areas that existing legislation is not working. The costs and benefits of controlling coastal development are examined. Firstly, a literature review of valuation studies identifies a range of values placed on the developed and undeveloped coastline for both users and local property owners. These values were then used in a model to evaluate policy options to control development of a stretch of coastline. The model indicates that a stricter control regime of coastal development may provide significant benefits.

杆状病毒包涵体蛋白的共同抗原性

在比对已公布的37种杆状病毒包涵体蛋白氨基酸序列的基础上,选定棉铃虫核型多角体病毒(HaNPV)多角体蛋白的两个高度保守多肽(54-113aa和206-245aa)制备多克隆抗体,用Western blot法检测这两个高度保守多肽与多种杆状病毒包涵体蛋白之间的血清学关系.结果表明,HaNPV多角体蛋白的两个多肽的抗体与14种核型多角体病毒的多角体蛋白和5种颗粒体病毒的颗粒体蛋白均有明显的杂交信号,表明杆状病毒的包涵体蛋白之间具有共同的抗原决定簇.根据杆状病毒包涵体蛋白之间的这种血清学关系,进一步讨论了利用免疫金试纸技术检测病毒杀虫剂中包涵体含量的可行性.     

华北地区水资源及水安全问题的思考与研究

结合中国科学院知识创新工程项目“华北地区水循环与水资源安全”的研究工作,论述华北地区紧迫的水安全问题与反思,展望国际水科学研究前沿与热点问题,介绍中国科学院在变化环境下的水循环、农业节水和水资源安全研究的阶段成果和近期研究行动计划,提出中国北方特别是华北地区的水文水资源科学研究与发展的几点建议。目的是研讨未来中国北方特别是华北地区水资源安全国家需求中的长远发展的前沿性问题。