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991.
文章综述了野生蜂资源多样性减少的原因,我国野生传粉蜂的研究现状及存在的问题,并提出保护野生传粉蜂资源的一些实施策略和建议。 相似文献
992.
2011年6月至2012年8月,采用样线法对神农架夏季鸟类资源进行了调查。共记录到鸟类140种,隶属于13目38科,占湖北省鸟类总数521种的26.87%。其中国家一级保护鸟类2种,国家二级保护鸟类14种,湖北省保护鸟类28种,中国特有种鸟类14种。该区鸟类群落总体多样性指数(H)为3.846,均匀性指数(J)为0.785,优势度(C)为0.034。β多样性指数分析表明:阔叶林—针阔混交林的鸟类群落相似性系数(S)最高,为0.552 6;阔叶林—水域的鸟类群落相似性系数最低,为0.052 6。区系组成上,东洋种84种(60.0%),古北种42种(30.0%),广布种14种(10.0%),鸟类区系以东洋界成分为主。 相似文献
993.
994.
为揭示南滚河自然保护区的昆虫多样性,采用样地调查法和文献研究法考察、分析该保护区的昆虫丰富度,合计记录12目,110科,604属,934种。在前人研究基础上新增记录1目,9科,127属,287种,显著丰富了蚁科、叶蝉科、蛱蝶科、白蚁科的物种。丰富度分析表明,在科级和属级阶元上丰富度依次为鳞翅目>鞘翅目>半翅目>膜翅目;在种级阶元上丰富度依次为鳞翅目>膜翅目>鞘翅目>半翅目。以往对南滚河自然保护区鳞翅目、鞘翅目、半翅目的研究比较全面,对双翅目、膜翅目、同翅目、直翅目、等翅目及其他小目的调查明显不足。与高黎贡山、文山、无量山自然保护区的昆虫考察结果相比较,南滚河自然保护区的昆虫丰富度最高。 相似文献
995.
采用PCR-DGGE技术对马鹿花5种种植模式土壤微生物多样性进行分析,结果表明:(1)5种种植模式土壤微生物垂直方向呈现随土层深度的增加其Simpson指数逐渐降低的趋势,且马鹿花-墨西哥柏林、马鹿花-蓝桉林Simpson指数高于其对照,马鹿花-三年桐林、马鹿花纯林Simpson指数低于其对照;(2)水平方向上马鹿花-蓝桉林总体丰富度、多样性指数及均匀度指数均最高,马鹿花-墨西哥柏林丰富度最低,马鹿花-三年桐林多样性及均匀度指数最低,相同条件下马鹿花纯林模式比马鹿花-三年桐林更优,中厚的棕壤较深厚的棕褐壤更适宜种植马鹿花. 相似文献
996.
农业生物多样性对维系农业系统的生态平衡和保障农业可持续发展起到重要的作用,为防治农作物的病虫害以提高作物产量,该文综述了农业种质资源多样性、农业物质多样性和农业景观多样性对农作物病虫害防控的研究进展,提出在现代农业防治中应尽量减少高毒农药的使用,利用农业生态中的生物多样性来持续控制农业病虫害发生的思路,以充分利用农业生物多样性在作物病虫害防控方面的作用。 相似文献
997.
U. Strecker 《Ecology of Freshwater Fish》2006,15(4):408-418
Abstract – Species that invade a new environment often may lead to population declines of endemic species. Here I document the invasions of an African cichlid (genus Oreochromis) in 1988 and the Mexican Astyanax fasciatus (Characidae) in 1996 into Laguna Chichancanab (Yucatan, Mexico), and the impact on an endemic Cyprinodon species flock and the poeciliid Gambusia sexradiata . After the invasion of Astyanax fasciatus , their relative abundances decreased enormously, most likely caused by predation on the fry. One species, Cyprinodon simus , might have even gone extinct or just occurs in extremely reduced numbers. Furthermore, it was observed that the percentage abundance of the detritivorous Cyprinodon beltrani increased significantly, in contrast to all other Cyprinodon species. This study also revealed that infestation by metacercaria (black spots) of an ectoparasitic trematode and of an endoparasitic nematode increased in the Cyprinodon spp. following the introduction of Oreochromis . Whereas the infestation by trematodes decreased after a period of 6 years, the prevalence and intensity of infestation by nematodes stayed at a high level. In contrast, in G. sexradiata the parasite load remained always very low. 相似文献
998.
Alifa Bintha Haque Nidhi Gloria D'Costa Mahi Washim Amit Robert Baroi Nazia Hossain Mashrur Hafiz Sumaiya Rahman Karabi Farhana Biswas 《水产资源保护:海洋与淡水生态系统》2021,31(6):1392-1409
- Devil rays (Mobula spp.) are globally threatened cartilaginous fishes that have attracted global conservation concern owing to their high extinction risk and lack of protection in many countries. Limited resources and data on threatened marine species, including devil rays, impede conservation actions, particularly in developing countries, many of which have high biodiversity.
- Devil ray catch is a component of artisanal fisheries in Bangladesh, but data on their fisheries and trade are limited. To characterize devil ray fishing practices, fishers’ perception and trade, 230 fishers and traders were interviewed between 4 June 2018 and 22 June 2019, in four areas of south-east Bangladesh. Catch data were also opportunistically collected at landing sites.
- Six devil ray species were documented, caught in an array of gill nets, set-bag nets and longlines. All interviewed fishers reported life-long devil ray bycatch in some numbers, and also noted a decline in catch over the last decade. Bottom trawling, increased bycatch levels, increased demand for devil ray products and, in some cases, ecosystem changes were identified by fishers as threats to devil ray populations.
- Unregulated and undocumented trade and retained bycatch, especially by gill nets and set-bag nets, are fuelled by local consumption of devil ray meat and international trade in meat and gill rakers. Compliance with international trade control treaties for all Mobula spp. or the Bangladeshi law protecting Mobula mobular was low, with the majority of fishers (87%, n = 174) unaware of their existence.
- To manage devil ray fisheries, and prevent possible population declines, we propose a combination of legally enforced gear modifications, and catch and trade control through community-owned implementation strategies. Additionally, we propose the simultaneous implementation of inclusive, community-based awareness and stewardship projects in conjunction with a coast-wide ray monitoring programme. Finally, we emphasize that more research and action rooted in a sustainable fishery model is urgently needed to protect Bangladeshi devil ray populations.
999.
- 1. The natural evolution of ponds leads to the filling up of these small ecosystems, and human intervention may sometimes be necessary to ensure their continued nature conservation interest.
- 2. In the arid karstic region of the ‘Causses du Quercy’ (France), there are numerous ponds bored into parts of the calcareous rock where water cannot percolate. Without human management they are destined to disappear, although they constitute the only available surface water resource on this limestone plateau.
- 3. Little information is available about the physical and chemical changes occurring as ponds go through different successional stages. A comparative study of three ponds at various stages of succession allowed an analysis to be made of the seasonal changes in a number of abiotic variables.
- 4. There was evidence that the temporal and spatial variability of abiotic factors (such as temperature, water level and dissolved oxygen concentrations) increased as ponds progressed through successional stages.
- 5. This study indicated that ponds varied in terms of plant and animal species richness and rarity, temperature, and oxygen concentration at different successional stages. Each pond supported a distinctive fauna. The results suggest that biotic diversity is, in part, driven by local‐scale physical and chemical heterogeneity. Management plans should be drawn at a scale that maintains the heterogeneity of such pond networks.
1000.
- Today, aquatic biodiversity suffers from many pressures linked to human activities, including climate change, which particularly affects alpine areas. Many alpine freshwater species have shifted their geographical distribution to colder areas, but a reduced availability of suitable habitats is also forecasted. New artificial water bodies could provide habitat enhancement opportunities, including small mountain reservoirs built to overcome a lack of snow during winter.
- To investigate the role of reservoirs as a habitat for freshwater invertebrates, a case study was conducted on eight reservoirs in the Swiss Alps. The study aimed to compare the water quality and freshwater biodiversity of the reservoirs with those of 39 natural and newly excavated ponds. Data were collected on physico‐chemistry, freshwater habitat structure, and aquatic insects (dragonflies and aquatic beetles).
- The study showed that the mountain reservoirs investigated did not differ from natural ponds in terms of surface area, conductivity, and trophic level. Similarly to natural ponds, reservoirs showed signs of impairment owing to surface run‐off carrying pollutants linked to ski tourism. They presented a low diversity of mesohabitats, and in particular lacked vegetation. Compared with natural ponds, the species richness in reservoirs was lower for dragonflies but not for beetles. At the regional scale, the community from the reservoirs was a subset of the natural ponds community, supporting 38% of the regional species richness for these two insect groups.
- The results suggest that mountain reservoirs are likely to be important for biodiversity in alpine areas, both as habitats and as stepping stones for species shifting their geographical range. These water bodies can be enhanced further by some nature‐friendly measures to maximize benefits for biodiversity, including margin revegetation or the creation of adjacent ponds. Ecological engineering needs to be innovative and promote freshwater biodiversity in artificial reservoirs.