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排序方式: 共有44条查询结果,搜索用时 31 毫秒
1.
罗布泊野骆驼自然保护区的建设及生物多样性保护   总被引:1,自引:0,他引:1  
新疆罗布泊野骆驼自然保护区位于我国西部极旱荒漠带 ,以保护世界濒危物种———野双峰驼为主要对象 ,同时也保护当地特有的地貌、盐泉、丝绸之路遗迹及其他珍稀动植物物种 ,面积 7 8× 10 4km2 。该保护区在世界生物多样性保护中有重大作用。由于周边地区经济的发展 ,对该保护区的影响逐渐扩大 ,威胁到野生动植物的生存安全 ,急需加强宣传、建卡、检查、巡护等保护管理措施 ,同时需要提高周边贫困社区人民生活水平 ,强化管制非法采矿业  相似文献   
2.
This article discusses the system of classification of forest types used by the Pwo Karen in Thung Yai Naresuan Wildlife Sanctuary in western Thailand and the role of nontimber forest products (NTFPs), focusing on wild food plants, in Karen livelihoods. The article argues that the Pwo Karen have two methods of forest classification, closely related to their swidden farming practices. The first is used for forest land that has been, or can be, swiddened, and classifies forest types according to growth conditions. The second system is used for land that is not suitable for cultivation and looks at soil properties and slope. The article estimates the relative importance of each forest type in what concerns the collection of wild food plants. A total of 134 wild food plant species were recorded in December 2004. They account for some 80–90% of the amount of edible plants consumed by the Pwo Karen, and have a base value of Baht 11,505 per year, comparable to the cash incomes of many households. The article argues that the Pwo Karen reliance on NTFPs has influenced their land-use and forest management practices. However, by restricting the length of the fallow period, the Thai government has caused ecological changes that are challenging the ability of the Karen to remain subsistence oriented. By ignoring shifting cultivators’ dependence on such products, the involvement of governments in forest management, especially through restrictions imposed on swidden farming practices, is likely to have a considerable impact on the livelihood strategies of these communities.  相似文献   
3.
The distribution and bioaccumulation of steroidal and phenolic endocrine disrupting chemicals (EDCs) were studied in various tissues of wild fish species from Dianchi Lake, China. In muscle tissue, 4-tert-octylphenol, 4-cumylphenol, 4-nonlyphenol and bisphenol A were detected in fish from each sampling site, with maximal concentrations of 4.6, 4.4, 18.9 and 83.5 ng/g dry weight (dw), respectively. Steroids (estrone, 17β-estradiol 17α-ethynylestradiol and estriol) were found at lower levels (<11.3 ng/g dw) and less frequently in muscle samples. The highest concentrations of steroids and phenols were found in liver, followed by those in gill and the lowest concentration was found in muscle. The field bioconcentration factors (BCFs) of phenols were calculated in fish species ranged from 18 to 97. Moreover, the measured tissue concentrations were utilized in order to estimate water concentration of steroids (4.4-18.0 ng/L). These results showed that steroidal and phenolic EDCs were likely ubiquitous contaminants in wild fish.  相似文献   
4.
The aim of this study was to evaluate the contamination of six edible wild species of mushrooms (Boletus pulverulentus, Cantharellus cibarius, Lactarius quietus, Macrolepiota procera, Russula xerampelina and Suillus grevillei) by heavy metals (Hg, Cd, Pb, Zn, Cu, Ni, Cr, Co, Mn and Fe). Mushroom samples were collected from sites contaminated by emissions from mining and processing of polymetallic ores in operation during the period 1969–1993 in Rudňany, southeast Slovakia. The four study sites spanned up to a 5-km distance from the emission source. The collected mushroom samples were analyzed using Flame Atomic Absorption Spectrophotometry and/or Flame Atomic Absorption Spectrophotometry with graphite furnace. Mercury, Cd and, in some samples, also Pb present the highest risks in terms of contamination of the food chain following subsequent consumption. The content of two metals in the dry matter (dm) of the mushrooms exceeded the limits set by the European Union (EU; Cd: 0.5 mg/kg dm, Pb: 1.0 mg/kg dm). The highest mean contents of the eight metals recorded for S. grevillei were 52.2, 2.15, 107, 104, 2.27, 2.49, 81.6 and 434 mg/kg dm for Hg, Pb, Zn, Cu, Ni, Cr, Mn and Fe, respectively. The highest content of Cd was recorded in M. procera (3.05 mg/kg dm) and that of Co in L. quietus (0.90 mg/kg dm). The calculated weekly intake for Hg, Pb and Cd shows that regular consumption of mushrooms from the studied area poses risks to human health.  相似文献   
5.
Abstract

Wild tomato leaves possess a pest-resistance mechanism in their glandular trichomes and the exudates they produce. Type IV and VI glandular trichomes on the leaves of five wild tomato accessions of Lycopersicum hirsutum f. glabratum (PI 126449, PI 134417, PI 134418, PI 251304, and LA 407) grown under greenhouse conditions were counted. Major chemical compounds from glandular leaf trichomes of the accessions tested were extracted, purified, and quantified at different periods during the growing seasons by gas chromatography (GC) and mass spectrometry (GC/MS). The toxicity of two methylketones (2-undecanone and 2-tridecanone), the major constituents of the accessions tested, to adults of the sweetpotato whitefly, Bemisia tabaci (Gennadius) and fourth instar larvae of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), was determined using no-choice bioassays. 2-undecanone caused 80% mortality of the fourth instar larvae of the CPB at the highest concentration tested (100 mg 2-undecanone mL? 1 of acetone) while 2-tridecanone caused 72% mortality of whiteflies at 20 mg 2-tridecanone mL? 1 of 65% ethanol. The concentration of 2-undecanone and 2-tridecanone on the leaves of each of the five accessions of L. hirsutum f. glabratum and the mass spectra of 2-undecanone and 2-tridecanone are presented. Overall, the concentration of 2-undecanone on the leaves was significantly higher than 2-tridecanone. Concentration of the two methylketones varied among accessions and sampling season. Plants produced the highest concentration of 2-undecanone during the month of August. On average, each plant of accession PI 251304 provided 354 g fresh leaves (averaging about 52,353 cm2 exposed leaf surface area) and produced 32.5 and 8.7 mg of 2-undecanone and 2-tridecanone, respectively. L. hirsutum f. glabratum accessions may become a valuable source of natural products, which could minimize reliance on synthetic pesticides.  相似文献   
6.
生物多样性与城市景观生态建设   总被引:4,自引:0,他引:4  
论述了生物多样性在城市景观中的重要作用,生物多样的现代城市中的衰落以及城市生物多样性保护与景观生态建设的关系,提出应将生物多样性保护计划同城市景观生态建设结合起来。  相似文献   
7.
分析了野风阀的降温原理及其影响因素,并对其使用提出改进建议。  相似文献   
8.
湖北省国家重点保护野生植物名录及特点   总被引:30,自引:0,他引:30  
对湖北省分布的国家新颁布的重点保护野生植物进行了研究 ,据统计湖北省国家重点保护野生植物共有 5 7种 ,其中一级 13种 ,二级 44种 ;其中包括栽培 11种 ,一级 4种 ,二级 7种。对湖北重点保护植物名录特点进行了分析。  相似文献   
9.
Abstract

The content of Al, As, Be, Cd, Ca, Cr, Co, Cu, Fe, Pb, Li, Mg, Mn, Ni, Rb, Se, Sr, and Zn in fruiting bodies of edible mushrooms Calocybe gambosa, Entoloma clypeatum, Entoloma saepium, Xerocomellus chrysenteron, and Amanita rubescens growing in an orchard planted with fruit trees and situated close to a high-grown forest was studied during years 2016–2018. A. rubescens showed the highest potential of the element accumulation with bioconcentration factors of 48.5, 16.2, 7.80, 6.53, 1.75, and 1.68 obtained for Rb, Cd, Cu, Zn, Sr, and Mg, respectively. Both Entoloma species accumulated the elements similarly with bioconcentration factors >1.0 obtained for Rb, Cu, Cd, and Mg. Bioconcentration factors <0.05 were obtained for Al, Cr, Fe, and Pb in all studied species. The contents of beryllium (<0.1?mg/kg dry matter) were always the lowest among the studied elements. The contents of some elements of studied mushroom species significantly fluctuated over the years. Despite the fact that some studied elements (As, Be, Cd, Pb, Ni) are considerably toxic for humans, the pronounced effect on health is not expected if the studied mushroom species are consumed occasionally and do not represent the main component of the diet.  相似文献   
10.
: The National Wild and Scenic River Act of 1968 was designed to protect the nation's unique waterways. This Act, however, has been criticized for negatively affecting areas it was intended to protect. Findings, based on field investigation in the Upper Mississippi River basin suggest that designation may serve as a factor for increasing recreational use levels on the protected rivers. This study discusses the social and recreational consequences of designating rivers and the attitudes of river users regarding designation.  相似文献   
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