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1.
黄土塬面是黄土高原地区主要的农业分布区和人口聚居地,地位十分重要。黄土塬面潜在蒸发量(ET0)的研究对于区域水循环研究、水土流失防治及农业的可持续发展具有重要意义。基于黄土塬面保护区1960—2017年的气象数据,利用Penman-Monteith模型、小波分析、Mann-Kendall非参数检验等方法研究了黄土塬面保护区ET0的变化规律及其与气象、环流因子间的关系。结果表明:(1)黄土塬面保护区多年平均ET0为1173.4 mm,总体呈现增长趋势,增长率为21.1 mm/10 a;其生长季平均ET0值及增长率均高于非生长季平均ET0。(2)该区多年平均ET0空间分布特征表现为东部高西部低,西部甘肃塬区多年平均ET0远低于东部山西塬区。(3)过去58年来,区域年均、生长季、非生长季ET0均呈现出增长趋势,但空间差异明显;研究区年均ET0存在着10年、30年和50年的震荡周期,其中以30年周期为主周期。(4)气温是控制区域ET0变化的最重要的气象因子,但气温对ET0的影响具有明显的空间差异,在整个研究区内最低气温影响最显著;而甘肃塬区和陕西塬区的ET0变化主要受平均气温变化的控制,在山西塬区最高气温的变化是区域ET0变化的主要控制因子。(5)遥相关分析结果显示太平洋/北美指数(PNA)与北大西洋年代尺度振荡(AMO)对该区域ET0变化有一定影响,西太平洋海温指数(WPI)的变化影响区域非生长季ET0变化。  相似文献   
2.
Many studies are based on the assumption that an area and its surrounding (buffer) area present similar environmental conditions and can be compared. For example, in order to assess the effectiveness of a protected area, the land use/cover changes are compared inside the park with its surroundings. However, the heterogeneity in spatial variables can bias this assessment: we have shown that most of the protected areas in Mexico present significant environmental differences between their interior and their surroundings. Therefore, a comparison that aims at assessing the effectiveness of conservation strategies, must be cautioned. In this paper, a simple method which allows the generation of a buffer area that presents similar conditions with respect to a set of environmental variables is presented. The method was used in order to assess the effectiveness of the Calakmul Biosphere Reserve, a protected area located in the south-eastern part of Mexico. The annual rate of deforestation inside the protected area, the standard buffer area (based upon distance from the protected area only) and the similar buffer area (taking into account distance along with some environmental variables) were 0.3, 1.3 and 0.6%, respectively. These results showed that the protected area was effective in preventing land clearing, but that the comparison with the standard buffer area gave an over-optimistic vision of its effectiveness.  相似文献   
3.
袁志英  郝江南 《地球与环境》2005,33(Z1):251-254
本文系笔者对贵阳地区主要地质环境和工程地质特点进行的初步总结,内容为贵阳地区主要岩土构成情况、分布范围及与之相应的岩土工程地质特点和主要的岩土工程地质问题的描述,旨在给同行提供宏观性的了解和方向性的参考。  相似文献   
4.
石油化工厂区土壤中总石油烃分布的研究   总被引:5,自引:0,他引:5  
为了进行石油化工厂区地下环境的现场评估,利用气相色谱法(EPA8015B)对其土壤中总石油烃(TPHs)进行了测定,测定结果以柴油范围的有机物(DRO)和润滑油范围的有机物(ORO)表示。结果表明:土壤各层DRO检出率在58%-72%之间,ORO检出率在82%-89%之间,大多数检出点位的DRO、ORO含量小于500mg/kg;个别点位的DRO、ORO高达30000mg/kg。  相似文献   
5.
本文对山西运城遥测地震台网及山西省数字流动地震观测仪记录的2005年1月31日至2月28日在山西省运城盆地范围内发生的7次高频地振动波形进行分析处理,精确划出了振动范围,并结合本区域内的地质构造分析震情趋势。  相似文献   
6.
高耸建筑物定向爆破中切口长度安全范围的研究   总被引:9,自引:0,他引:9  
爆破拆除高耸筒体结构时 ,爆破切口长度的合理选取是爆破成功的重要因素。目前的实践经验 ,爆破切口长度取为切口处筒体圆周长的 6 0 %~ 6 6 % (即 3/ 5~ 2 / 3) ,按此取值范围进行施工 ,爆破效果的好坏并存 ,事故仍有发生 ,这说明此取值范围偏大。借助有限元软件ANSYS ,通过数值计算 ,可获得起爆瞬间 ,在结构自重作用下引起的爆破切口支撑部的应力与应变状态 ,因而 ,可分析出爆破切口长度较安全的取值范围。对比实际拆除爆破的效果 ,爆破切口长度取切口处筒体圆周长的 6 2 %~ 6 4 %是比较安全适宜的。数值分析所得出的结论 ,对爆破设计施工有一定的借鉴意义  相似文献   
7.
Like many federal statutes, the U.S. Endangered Species Act (ESA) contains vague or ambiguous language. The meaning imparted to the ESA's unclear language can profoundly impact the fates of endangered and threatened species. Hence, conservation scientists should contribute to the interpretation of the ESA when vague or ambiguous language contains scientific words or refers to scientific concepts. Scientists need to know at least these 2 facts about statutory interpretation: statutory interpretation is subjective and the potential influence of normative values results in different expectations for the parties involved. With the possible exception of judges, all conventional participants in statutory interpretation are serving their own interests, advocating for their preferred policies, or biased. Hence, scientists can play a unique role by informing the interpretative process with objective, policy‐neutral information. Conversely, scientists may act as advocates for their preferred interpretation of unclear statutory language. The different roles scientists might play in statutory interpretation raise the issues of advocacy and competency. Advocating for a preferred statutory interpretation is legitimate political behavior by scientists, but statutory interpretation can be strongly influenced by normative values. Therefore, scientists must be careful not to commit stealth policy advocacy. Most conservation scientists lack demonstrable competence in statutory interpretation and therefore should consult or collaborate with lawyers when interpreting statutes. Professional scientific societies are widely perceived by the public as unbiased sources of objective information. Therefore, professional scientific societies should remain policy neutral and present all interpretations of unclear statutory language; explain the semantics and science both supporting and contradicting each interpretation; and describe the potential consequences of implementing each interpretation. A review of scientists’ interpretations of the phrase “significant portion of its range” in the ESA is used to critique the role of scientists and professional societies in statutory interpretation.  相似文献   
8.
The designation of no‐take marine reserves involves social and economic concerns due to the resulting displacement of fishing effort, when fishing rights are removed from those who traditionally fished within an area. Displacement can influence the functioning of the fishery and success of the reserve, yet levels of displacement are seldom quantified after reserve implementation and very rarely before that. We devised a simple analytical framework based on set theory to facilitate reserve placement. Implementation of the framework requires maps of fishing grounds, fishing effort, or catch per unit effort for at least 2 years. The framework quantifies the level of conflict that a reserve designation might cause in the fishing sector due to displacement and the opportunities to offset the conflict through fisher spatial mobility (i.e., ability of fishers to fish elsewhere). We also considered how the outputs of the framework can be used to identify targeted management interventions for each fishery. We applied the method in Honduras, where the largest marine protected area in Central America is being placed, for which spatial data on fishing effort were available for 6 fisheries over 3 years. The proposed closure had a greater negative impact on the shrimp and lobster scuba fisheries, which concentrated respectively 28% and 18% of their effort inside the reserve. These fisheries could not accommodate the displacement within existing fishing grounds. Both would be forced to stretch into new fishing grounds, which are available but are of unknown quality. These stakeholders will likely require compensation to offset costly exploratory fishing or to travel to fishing grounds farther away from port.  相似文献   
9.
Management activities such as law enforcement and community outreach are thought to affect conservation outcomes in protected areas, but their importance relative to intrinsic environmental characteristics of the parks and extrinsic human pressures surrounding the parks have not been explored. Furthermore, it is not clear which is more related to conservation outcomes—the management itself or local people's perceptions of the management. We measured objective (reports by park staff) and subjective (reports by local people) levels of community outreach and law enforcement based on responses to 374 questionnaires. We estimated mammal abundance and diversity of 6 protected areas based on data from 115 camera traps in Xishuangbanna, southwest China, a biodiversity hotspot with high hunting and land-conversion pressures. We then examined correlations among them and found that local people's perception of law enforcement was positively related to the local abundance of 2 large, hunted species, wild boar (Sus scrofa) (β = 15.22) and muntjac (Muntiacus vaginalis) (β = 14.82), but not related to the abundance of smaller mammals or to objective levels of enforcement. The subjective frequency of outreach by park staff to local communities (β = 3.42) and park size (β = 3.28) were significantly and positively related to mammal species richness, whereas elevation, human population density, and subjective frequency of law enforcement were not. We could not conclude that community outreach and law enforcement were directly causing increased mammal abundance and diversity. Nevertheless, the patterns we detected are some of the first empirical evidence consistent with the idea that biodiversity in protected areas may be more positively and strongly related to local perceptions of the intensity of park management than to either intrinsic (e.g., elevation, park size) or extrinsic (e.g., human population density) environmental factors.  相似文献   
10.
Conservation easements are a standard technique for preventing habitat loss, particularly in agricultural regions with extensive cropland cultivation, yet little is known about their effectiveness. I developed a spatial econometric approach to propensity‐score matching and used the approach to estimate the amount of habitat loss prevented by a grassland conservation easement program of the U.S. federal government. I used a spatial autoregressive probit model to predict tract enrollment in the easement program as of 2001 based on tract agricultural suitability, habitat quality, and spatial interactions among neighboring tracts. Using the predicted values from the model, I matched enrolled tracts with similar unenrolled tracts to form a treatment group and a control group. To measure the program's impact on subsequent grassland loss, I estimated cropland cultivation rates for both groups in 2014 with a second spatial probit model. Between 2001 and 2014, approximately 14.9% of control tracts were cultivated and 0.3% of treated tracts were cultivated. Therefore, approximately 14.6% of the protected land would have been cultivated in the absence of the program. My results demonstrate that conservation easements can significantly reduce habitat loss in agricultural regions; however, the enrollment of tracts with low cropland suitability may constrain the amount of habitat loss they prevent. My results also show that spatial econometric models can improve the validity of control groups and thereby strengthen causal inferences about program effectiveness in situations when spatial interactions influence conservation decisions.  相似文献   
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