Fish species richness in lakes of the northeastern lowlands in Germany   总被引：1，自引：0，他引：1  

R. Eckmann 《Ecology of Freshwater Fish》1995,4(2):62-69

Fish species richness was assessed by electrofishing and gillnetting in 16 lakes of the northeastern lowland in Germany (the Schorfheide biosphere reserve). The lakes range from 0.03 to 10.55 km² and support between 5 and 14 fish species. Species richness is significantly correlated with lake area in an exponential and a power model. Richness is also correlated with shoreline development and total dissolved solids. This supports the hypothesis that larger areas contain more species within a taxonomic group due to increased habitat diversity. The slope of the species-area curve is low compared with most other studies of fish species richness in lakes, and the intercept value is high. This is interpreted as the result of high habitat and food diversity, lack of stress from abiotic factors, and the small regional species pool from which these lakes can be colonized. Two species inventories, one from the beginning of this century and one from the 1950s, are available for comparison. Average species richness did not change during the last decades. Species turnover rates were not related to the degree of anthropogenic eutrophication or to the intensity of fishery exploitation in these lakes. On the species level, however, one effect of accelerated eutrophication is apparent, the disappearance of 4 bottom-living species from one to 6 of the study lakes.  相似文献   

速生桉人工林与红椎林昆虫群落结构比较研究     

李成  贤振华  郑霞林  韦继光 《广西农业科学》2014,(4):585-589

[目的]比较速生桉纯林、红椎纯林及两林交界处林地的昆虫群落结构,探讨速生桉人工林对红椎林昆虫群落的影响,为科学合理地规划速生桉发展提供参考.[方法]采用GPS定位样地,用目测、套袋震落、采集鉴定等方法,调查速生桉人工纯林、红椎纯林、两林交界处桉树林和红椎林等4种林分的昆虫种类及种群数量,并分析其丰富度、均匀度、多样性等指数.[结果]4种类型林地共查得昆虫15目74科148种12874头.4种类型林地昆虫群落目数排序为：交界处的红椎林=红椎纯林＞交界处的速生桉林＞速生桉纯林;科数排序为：交界处的红椎林＞红椎纯林＞交界处的速生桉林＞速生桉纯林,种数排序与科数相同;个体总数排序为：速生桉纯林＞红椎纯林＞交界处的速生桉林＞交界处的红椎林.4种类型林地昆虫多样性指数与丰富度排序相同,为交界处的红椎林＞红椎纯林＞交界处的速生桉林＞速生桉纯林;昆虫群落物种均匀度指数排序为：交界处的红椎林＞红椎纯林＞速生桉纯林＞交界处的速生桉林.[结论]速生桉林昆虫物种多样性低于红椎林,交界处昆虫物种多样性高于纯林.速生桉林与红椎林相邻种植对双方无不利影响.  相似文献   

宁夏云雾山国家自然保护区蝶类群落结构与多样性     

常春燕  贾彦霞  王新谱 《西北农业学报》2014,23(11):168-172

由于蝴蝶对环境变化反应比较灵敏,常被作为检测环境质量变化的指示生物。对宁夏云雾山国家级自然保护区蝶类群落的结构组成与多样性做了初步调查。结果表明:云雾山蝴蝶共有29种,隶属于6科26属。其中,眼蝶科的属和物种数量最多,为8属8种;凤蝶科最少,仅1属1种。通过Margalef物种丰富度指数、Shannon-Wiener多样性指数、Pielou均匀度指数和Berger-Parker优势度指数对蝶类的多样性进行分析,眼蝶科的多样性指数最高,但均匀度指数和优势度指数均最低,分别为1.57、0.76和0.28;弄蝶科的丰富度指数最高,达到1.31;蛱蝶科的优势度指数最高,达到0.44;灰蝶科的均匀度指数最高,但多样性指数最低,分别为0.96和1.34;粉蝶科的丰富度指数最低,为0.82。眼蝶科在云雾山保护区是优势科,物种丰富,但物种相对集中,群落结构不稳定,而凤蝶科物种较为贫乏,需要对其加以保护。  相似文献   

Seasonal dynamics of fish assemblage in a pond canal     

Jiří Musil  Zdenek Adámek  Christian Baranyi 《Aquaculture International》2007,15(3-4):217-226

The annual dynamics of fish assemblage in a pond-connecting canal of a South Moravian pond aquaculture facility was studied to reveal potential assemblage effects on pond stocks and vice versa. The species richness of fish assemblage and seasonal dynamics of its development were predominantly dependent upon the fish stock of the interconnected ponds (particularly due to escapees during the period of pond harvesting), which contributed to a considerable increase of commercial fish species occurrence. Using a seasonal parameter, the season proved to have a major impact on fish assemblage dynamics (r = −0.71, P < 0.001). Spring samples were dominated by commercial fishes of aquaculture origin (mainly Cyprinus carpio). Occurrence of several fish species originating from the wild (bleak, Alburnus alburnus, chub, Leuciscus cephalus and roach, Rutilus rutilus) was also reported. The pond canal was found to be an important reservoir site of persistent survival and potential subsequent spreading of some undesirable alien fishes such as topmouth gudgeon (Pseudorasbora parva) and gibel carp (Carrasius auratus). Moreover, more attention should be paid to the potential negative impacts of all fishes of aquaculture origin upon the natural ecosystem and to the adverse effects due to the immigration of wild fish into aquaculture pond farming units.  相似文献   

Tracking the Trade in Ornamental Coral Reef Organisms: The Importance of CITES and its Limitations     

Andrew W. Bruckner 《Aquarium Sciences and Conservation》2001,3(1-3):79-94

The extraction of coral reef organisms for the aquarium and curio trade is reported to be contributing to coral reef degradation. The total international trade and associated impacts are unknown, because data are collected only for organisms listed on Appendix II of CITES, which include stony corals, antipatharians and giant clams. CITES data indicate that trade in live stony coral and reef substrate (live rock) increased by 15–30% each year during the 1990s, with most exports since 1992 from Indonesia and Fiji. Overall, 19% of all stony coral traded (by item) from 1985 to 1997 was live; 71kern-1pt% of this was traded between 1993 and 1997 (52% of total trade). Although tracking trade using information from the CITES Trade Database provides limited information (e.g., coral is reported to genus, and volume is reported by item or weight), the CITES mechanism promotes the development of strategies to protect resources. In response to CITES requirements, Indonesia developed a management plan for sustainable harvest of corals, but not for non-CITES listed species such as soft corals and fishes. Trade in hard and soft coral provides revenue for developing countries; however, in order to be of lasting value the industry must be developed with a conservation ethic. This requires support for international programs such as CITES, management plans for sustainable harvest, and improved enforcement.  相似文献   

Grassland responses to grazing disturbance: plant diversity changes with grazing intensity in a desert steppe     

L. Deng  S. Sweeney  Z.‐P. Shangguan 《Grass and Forage Science》2014,69(3):524-533

This study quantifies the impact of four different grazing regimes (heavy, moderate, light and ungrazed) on the vegetation dynamics of rangeland ecosystems along the southern boundary area of the Mu Us Desert, China. As the grazing intensities decreased, the soil quality, canopy cover, height, density, above‐ and below‐ground biomass, litter, root/shoot ratio and native plant (Aneurolepidium dasystachys) and grass abundances significantly increased; the above‐ground biomass of grasses increased, but the above‐ground biomass of forbs decreased. Ungrazed grassland has significantly improved from grasslands experiencing three other levels of grazing pressure, especially in the grassland biomass. Species richness increased as the grazing intensity decreased in the grazing grasslands, but peak species richness appeared under moderate and light grazing against lower productivity. Grazing exclusion causes desirable transitions in plant communities of desert steppe rangelands. Therefore, appropriate and efficient grazing exclusion is an available way to counteract local grassland degradation and promote rangeland sustainability.  相似文献   

海南中部山区植被演变阶段植物物种多样性与群落结构多样性变化规律   总被引：2，自引：0，他引：2  

陈伟  杨小波  李时兴  林明基  龙文兴 《热带作物学报》2014,35(4):784-790

以海南中部山区的草地、灌丛、次生林和原始林为演替系列,研究植被演替过程中群落结构多样性与物种多样性的变化规律。结果表明,群落演替过程中植物科属种数、总体Shannon-Wiener指数和Margalef指数、乔灌木层的Shannon-Wiener指数和Margalef指数及垂直结构多样性指数都显著增大;群落结构多样性指数分别与群落植物科属种数、总体alpha物种多样性指数、灌木层和乔木层物种alpha多样性指数都显著正相关。通过恢复演替,植被复杂性和质量都呈增大趋势。  相似文献   

呼和浩特市云杉土壤真菌种群分布     

白丽梅  包晓英  姜海燕 《安徽农业科学》2014,(18):5787-5788

[目的]明确云杉土壤真菌的种群结构。[方法]利用选择性培养基,研究了云杉土壤真菌的数量分布和种群组成。[结果]云杉土壤真菌数量随生长季月份的变化趋势是7月〉6月〉8月〉5月〉9月〉10月〉4月,垂直变化趋势是随着土壤深度的增加,真菌数量呈递减趋势;云杉土壤中共分离到产孢真菌332株,分属于24属,优势菌属为腐霉属、毛霉属、青霉属、汉斯霉属。[结论]云杉土壤真菌种群分布具有多样性。  相似文献   

沙坡头国家级自然保护区荒漠植被关键群落的最小面积与物种多样性   总被引：1，自引：0，他引：1  

王旭  曹蕾  孙杰  裘骏一 《安徽农业科学》2014,(34):12235-12238

以处于腾格里沙漠东南缘的沙坡头国家级自然保护区干旱荒漠生态系统的植被关键群落为研究对象,采用“种-面积曲线”的方法确定关键群落最小面积,并在此基础上使用α多样性指数表征物种多样性.共选取4种饱和曲线模型进行拟合,研究结果表明对荒漠植被群落而言,S=c/（1 ＋ae-bA）和S=c-ae-bA模型具有更好的拟合优度和更高的准确性.当比例因子ρ取0.6、0.7、0.8时,群落最小面积分别为18 m2、24 m2、32 m2,可满足包括总群落的60％、70％、80％的植物种类的中等精度要求;当比例因子ρ取0.9时,群落最小面积为45 m2,可满足包括总群落的90％的植物种类的高等精度要求.该区域物种多样性并不十分复杂,灌木层的生态学地位极其显著,发挥着不可替代的作用,群落的稳定性和生态功能也主要由灌木层中的优势种决定.  相似文献   

东风西沙水源地浮游植物种类组成与数量分布特征     

姚磊 《安徽农业科学》2014,(16):5186-5188,5285

分析了东风西沙水源地浮游植物种类组成、优势种分布、群落结构分布以及多样性等特征.结果表明,东风西沙水源地共监测出藻类6门共64种（属）,分别为蓝藻、绿藻、硅藻、隐藻、裸藻、金藻,其中硅藻和绿藻共47种,为水源地的主要浮游植物种类;浮游植物优势种单一,主要为硅藻门的短小舟形、克洛脆杆藻,隐藻门的尖尾蓝隐藻,以及蓝藻门的铜绿微囊藻,且优势度值较小;监测期间浮游植物密度为8.20×10^5 ～8.40×10^6 cells/L,均值为3.71×10^6 cells/L;群落特征指数统计结果表明东风西沙目前水质较好,总体上处于轻或无污染状态.  相似文献