首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
耐盐(CaCl2)皂素废水降解菌的分离及特性   总被引:4,自引:0,他引:4  
从湖北省某皂素生产废水池底污泥中分离出2株耐高盐(CaCl2)皂素废水降解菌,编号分别为B723—1和B723—3,并进行菌株的鉴定和生长特性以及不同盐度迫胁下胞内游离氨基酸、蛋白质、膜的相对透性的研究,结果发现:(1)菌株B723—1与扩展短杆菌的同源性为98.0%~99.0%,B723—3与松鼠葡萄球菌的同源性为98.0%~99.0%:(2)两菌株均能在0.0%~9.0%CaCl2范围内生长良好;(3)菌株B723—1和B723—3的适宜生长温度分别是20~35oC和25~37oC,两者均在pH7.0~10.0生长;(4)当耐盐菌株受到1.8%、3.6%、5.4%和9.0%CaCl2盐迫45min时,其胞内会迅速积累大量氨基酸来平衡外界的高盐渗透压,且其胞内蛋白质含量均高于对照组(未受盐迫),而其膜的相对通透性低于非耐盐菌株.图4表1参11.  相似文献   

2.
作者于1994年12月~1995年4月对黑眉锦蛇进行了人工越冬试验。试验结果发现此蛇冬眠温度为5~8℃,高于8℃以上时出现活动;阳光直射可调节蛇洞温度;保持供应饮水在越冬期很重要;越冬期自然损失率为18.09%,体长并有缩短的现象,其体长缩短率为4.55%;冬季仍然出现蜕皮现象。  相似文献   

3.
内蒙古中东部大针茅群落土壤线虫多样性研究   总被引:4,自引:0,他引:4  
2003年在内蒙古西乌旗大针茅草原,根据土壤深度0~10cm、1020cm、20~30cm分层采样,定量分析土壤线虫群落的多度,并对土壤线虫群落多样性和群落内线虫营养类型进一步分析.结果表明,该群落中土壤线虫包括50属和24科,其中矮化属、拟盘旋属、丽突属为优势属,特别是矮化属线虫数量异常高.土壤线虫群落的垂直分布呈现表聚型.就功能类群而言,植食性线虫在各层中的比例最高,为69.4%~81.3%,食真菌类线虫的比例最低,为0.9%~2.4%,而食细菌类线虫比例为13.9%-20.9%,食真菌类线虫和食细菌类线虫的比值为0.067~0.133.表6参29  相似文献   

4.
游蛇科(Colubridae)10种的随机扩增多态DNA研究   总被引:6,自引:1,他引:6  
用随机扩增多态DNA(RAPD)技术对游蛇科10种蛇基因组DNA的多态性进行了分子遗传标记的研究,所得数据经聚类分析结果提示,1.蛇类种内个体间在着遗传多样性妈个体间的差异,随机扩增多态DNA片段共享度的分析表明,种间差异显著大于种内个体间的差异,说明在研究种间系统演化关系时,可以用随机取样的个体代表一个种作种间的比较.2.锦蛇属是一高度分化的大属,本研究中的5种锦蛇间,玉斑锦蛇和红点锦蛇关系的较  相似文献   

5.
用随机扩增多态DNA(RAPD)技术对游蛇科10种蛇基因组DNA的多态性进行了分子遗传标记的研究.所得数据经聚类分析结果提示:1.蛇类种内个体间存在着遗传多样性即个体间的差异,随机扩增多态DNA片段共享度的分析表明,种间差异显著大于种内个体间的差异,说明在研究种间系统演化关系时.可以用随机取样的个体代表一个种作种间比较.2.锦蛇属是一高度分化的大属,本研究中的5种锦蛇间.玉斑锦蛇和红点锦蛇关系较近.可以井为1组.另3种归为1组还是分为3个不同的组尚难定论.3.游蛇科6个属之间.锦蛇属、乌梢蛇属和鼠蛇属3属间亲缘关系较近.Rhabophis和Sinonatrix与链蛇属较近.它们可能代表该科中较原始的类群.  相似文献   

6.
安徽省宣州扬子鳄饲养种群繁殖现状分析   总被引:10,自引:0,他引:10  
对1993 ~1998 年安徽省扬子鳄繁殖研究中心内的亲代与子代鳄的繁殖情况进行了统计研究,结果表明:扬子鳄亲代卵的平均受精率为(75.66±2.29) % ,子一代为(69 .24 ±5 .12) % ,经t 检验,两者差异显著;亲代产卵孵化幼鳄的平均畸形率为(0.30 ±0.20) % ,而子一代产卵幼鳄平均畸形率为(1 .85±0.95) % ,经t 检验,两者差异显著.但受精卵幼鳄孵化率在两代间差异不显著.通过饲养种群的家系和有效群体大小分析,作者认为造成子代鳄的繁殖率下降和畸形率上升的原因与近亲繁殖有关.对扬子鳄的遗传保护研究提出了建议.  相似文献   

7.
上海外环林带小气候效应的研究(Ⅰ)   总被引:3,自引:0,他引:3  
通过对具有代表性的上海外环林带小气候的测定,结果表明,在春夏林内白天最高气温低于旷地1.4℃,而秋冬则分别高于旷地1.1℃和2.7℃的特征;春、秋、冬林内最低气温高于旷地0.52到1.1℃;一年中春、夏、秋相对湿度高于旷地4%-11.4%,尤以夏季增湿最大,昼夜与旷地湿度差值分别达到11.4%和6.9%,林带在夏秋白天的降温和夏秋的增湿作用十分明显,林带明显具有冬暖夏凉和冬干夏湿的作用。林带在春夏季对林带北缘及下风向90m区域具有稳定其小气候的作用。一年中春、夏、秋林内气温日变化幅度比旷地小1.3~0.7℃,而冬季林内气温日变化幅度反比旷地大2.1℃;相应的夏、秋林内相对湿度日变化幅度比旷地高4.4%-6.7%,而冬、春林内相对湿度日变化幅度反比旷地低1.10/0--2.6%。在冬季中午林带内蓄热能力比旷地高约3℃,林中最低气温普遍比林外高0.5℃,具有明显保温作用。  相似文献   

8.
滨海沙地木麻黄林生态系统的凋落物及其热值研究   总被引:2,自引:0,他引:2  
采用定位研究的方法,在福建惠安赤湖防护林场定期收集木麻黄林分的凋落物,开展凋落物的归还量和热值的研究.结果表明,木麻黄林凋落物年归还量为14.17thm^-2 a^-1,小枝占总归还量的72.19%,其他各组分占27.81%.凋落物灰分含量:小枝4.39%~5.65%,枝条3.52%~5.65%,球果2.63%~4.23%;凋落物干重热值为:小枝20.51~21.68kJ/g,枝条19.63~20.21kJ/g,球果18.27~20.63kJ/g;凋落物去灰分热值为:小枝21.48~22.69kJ/g,枝条21.48~22.69kJ/g,球果18.91~21.49kJ/g.图1表8参26  相似文献   

9.
杜仲叶.粉对肉鸡生产性能及血液生化指标的影响   总被引:3,自引:0,他引:3  
为探明杜仲叶粉对肉鸡生产性能及血液生化指标的影响,按0.5%、1%、1.5%、2%的比例在肉鸡的基础日粮中添加杜仲叶粉,以不添加杜仲叶粉作为对照,经60天饲养试验期后,对各组鸡的日增重、饲料报酬(增重与耗料之比)、胴体品质及血液生化指标进行检测,结果表明:杜仲叶粉能提高肉鸡饲料报酬,改善胴体品质,改善血液生化指标.  相似文献   

10.
星湖沉积物特性研究   总被引:4,自引:0,他引:4  
以肇庆星湖为研究对象,研究了其沉积物的各种特性。研究表明:(1)星湖沉积物的矿相(晶体物)主要为石英、伊利石、长石、绿泥石等;(2)沉积物中的TP、TN含量,基本随湖水交换和季节变化而变化,与交换量有着简单反比关系,其TP的含量在0.03%~0.06%之间,TN在0.19%~0.28%之间,内负荷较为严重;(3)沉积物的沉降存在很大的不均衡性;(4)沉积物营养物的释放受环境因子影响,其中溶解氧对N、P的释放都有较大的影响,温度对P的影响较N多一些,而保持水体中性,则有利于水体的稳定。  相似文献   

11.
Conservation science is a crisis discipline in which the results of scientific enquiry must be made available quickly to those implementing management. We assessed the extent to which scientific research published since the year 2000 in 20 conservation science journals is publicly available. Of the 19,207 papers published, 1,667 (8.68%) are freely downloadable from an official repository. Moreover, only 938 papers (4.88%) meet the standard definition of open access in which material can be freely reused providing attribution to the authors is given. This compares poorly with a comparable set of 20 evolutionary biology journals, where 31.93% of papers are freely downloadable and 7.49% are open access. Seventeen of the 20 conservation journals offer an open access option, but fewer than 5% of the papers are available through open access. The cost of accessing the full body of conservation science runs into tens of thousands of dollars per year for institutional subscribers, and many conservation practitioners cannot access pay‐per‐view science through their workplace. However, important initiatives such as Research4Life are making science available to organizations in developing countries. We urge authors of conservation science to pay for open access on a per‐article basis or to choose publication in open access journals, taking care to ensure the license allows reuse for any purpose providing attribution is given. Currently, it would cost $51 million to make all conservation science published since 2000 freely available by paying the open access fees currently levied to authors. Publishers of conservation journals might consider more cost effective models for open access and conservation‐oriented organizations running journals could consider a broader range of options for open access to nonmembers such as sponsorship of open access via membership fees. Obtención de Acceso Abierto a la Ciencia de la Conservación  相似文献   

12.
A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.  相似文献   

13.
Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.  相似文献   

14.
Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.  相似文献   

15.
An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.  相似文献   

16.
Summary Two South American polyphagous leaf beetles,Diabrotica speciosa andCerotoma arcuata, selectively accumulated the bitter tasting compound 23,24-dihydrocucurbitacin D in their body after ingesting root tissues of cucurbit plants. Similarly, three Asian Cucurbitaceae-feeding specialists in the genusAulacophora were found to sequester the same compound. Cucurbitacin analogs were shown to deter feeding by a bird predator, indicating an allomonal role for these compounds in cucurbitacin-associated chrysomelid leaf beetles both of New and Old Worlds. The strong affinity to cucurbitacins, selective sequestration of the analogs and consequent protection from predators suggested an ecological adaptation mechanism developed in common among these two geographically isolated subtribes in the Luperini.  相似文献   

17.
Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.  相似文献   

18.
Abstract: In East Africa fire and grazing by wild and domestic ungulates maintain savannas, and pastoralists historically set fires and herded livestock through the use of temporary corrals called bomas. In recent decades traditional pastoral practices have declined, and this may be affecting biodiversity. We investigated the effects of prescribed fires and bomas on savanna bird communities in East Africa during the first and second dry seasons of the year (respectively before and after the rains that mark the onset of breeding for most birds). We compared abundance, richness, and community composition on 9‐ha burned plots, recently abandoned bomas, and control plots in the undisturbed matrix habitat over a 3‐year period. Generally, recently burned areas and abandoned bomas attracted greater densities of birds and had different community assemblages than the surrounding matrix. The effects of disturbances were influenced by interactions between primary productivity, represented by the normalized difference vegetation index, and time. Bird densities were highest and a greater proportion of species was observed on burned plots in the months following the fires. Drought conditions equalized bird densities across treatments within 1 year, and individuals from a greater proportion of species were more commonly observed on abandoned bomas. Yearly fluctuations in abundance were less pronounced on bomas than on burns, which indicate that although fire may benefit birds in the short term, bomas may have a more‐lasting positive effect and provide resources during droughts. Several Palearctic migrants were attracted to burned plots regardless of rainfall, which indicates continued fire suppression may threaten their already‐declining populations. Most notably, the paucity of birds observed on the controls suggests that the current structure of the matrix developed as a result of fire suppression. Traditional pastoralism appears critical to the maintenance of avian diversity in these savannas.  相似文献   

19.
20.
How should managers choose among conservation options when resources are scarce and there is uncertainty regarding the effectiveness of actions? Well‐developed tools exist for prioritizing areas for one‐time and binary actions (e.g., protect vs. not protect), but methods for prioritizing incremental or ongoing actions (such as habitat creation and maintenance) remain uncommon. We devised an approach that combines metapopulation viability and cost‐effectiveness analyses to select among alternative conservation actions while accounting for uncertainty. In our study, cost‐effectiveness is the ratio between the benefit of an action and its economic cost, where benefit is the change in metapopulation viability. We applied the approach to the case of the endangered growling grass frog (Litoria raniformis), which is threatened by urban development. We extended a Bayesian model to predict metapopulation viability under 9 urbanization and management scenarios and incorporated the full probability distribution of possible outcomes for each scenario into the cost‐effectiveness analysis. This allowed us to discern between cost‐effective alternatives that were robust to uncertainty and those with a relatively high risk of failure. We found a relatively high risk of extinction following urbanization if the only action was reservation of core habitat; habitat creation actions performed better than enhancement actions; and cost‐effectiveness ranking changed depending on the consideration of uncertainty. Our results suggest that creation and maintenance of wetlands dedicated to L. raniformis is the only cost‐effective action likely to result in a sufficiently low risk of extinction. To our knowledge we are the first study to use Bayesian metapopulation viability analysis to explicitly incorporate parametric and demographic uncertainty into a cost‐effective evaluation of conservation actions. The approach offers guidance to decision makers aiming to achieve cost‐effective conservation under uncertainty.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号