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1.
四川及重庆蕨类植物区系组成、特有现象和珍稀种类   总被引:2,自引:0,他引:2  
四川及重庆为我国蕨类植物最丰富的区域之一,总计有52科,141属,约880种。鳞毛蕨科、蹄盖蕨科和水龙骨科是最重要的3个科,其种数占本区种数的50.5%,金星蕨科、中国蕨科和铁角蕨科在本区也有较多的种类分布。在本区主要的属为耳蕨属、鳞毛蕨属和蹄盖蕨属,它们的种数都超过50种,合计占本区种数的22.8%,其次有铁角蕨属、瓦韦属和毛蕨属,其种数都逾25种,而有近85%的属不足10种。热带成分的属在本区占53.9%,但它们的区系存在度不大;东亚分布的属占16.3%,其区系存在度相对较大;温带分布的属占12.7%。本区无特有科;仅光叶蕨属1个特有属,还有6个中国特有属;有387种为中国特有种,约占本区种数的44%。特有种的32%为本区特有,其余以与中国西南片区(占22.5%)和整个南方片区(占26.1%)共有为主。本区被列入国家重点保护的珍稀濒危蕨类植物有10种,其中1级3种,2级7种。  相似文献   

2.
长江镇江段不同生境类型底栖动物群落结构研究   总被引:2,自引:0,他引:2  
2010年3~12月在长江镇江段进行4次采样共采集到底栖动物26种,隶属于7科21属,其中水栖寡毛类2科7属12种,多毛类1科1属种,软体动物2科4属4种,水生昆虫2科9属9种。长江镇江段共有4个优势种:厚唇嫩丝蚓(Teneridrilus mastix)、苏氏尾鳃蚓(Branchiura sowerbyi)、多鳃齿吻沙蚕(Nephthys polybranchia)和长足摇蚊(Tanypus sp.)。底栖动物平均栖息密度和生物量分别为74 ind./m2和02 g/m2。各种生境类型中,保护区的底栖动物密度和生物量相对较高,北湖次之,主航道最低。同时存在着季节变动,密度以春夏较高,秋冬较低,生物量以春秋较高,冬夏较低。各季度功能摄食类群密度相对丰度以直接收集者所占比例较高,滤食收集者次之。比较长江下游各江段,底栖动物群落有较大差异:密度最高值出现在扬中段,最低值出现在镇江段;生物量最高值出现在江阴段,最低值出现在镇江段;而种类数在镇江段和扬中段较高,江阴段较低  相似文献   

3.
湖北省珍稀濒危保护水禽物种多样性及种群数量   总被引:3,自引:0,他引:3  
使用直接计数法和专项调查法于1996年5月~2003年7月对湖北省珍稀濒危保护水禽物种多样性和种群数量进行了研究。结果表明:湖北省珍稀濒危保护水禽有45种,隶属于6目9科24属;记录到34种,其中有黄嘴白鹭和小苇鳽2个新记录种。按区系型分,古北界种类占优势,有35种,东洋种8种,广布种2种;按季节型分,冬候鸟为主体,有30种,夏候鸟8种,旅鸟5种,留鸟2种;按生活型分,涉禽23种,游禽22种,种类几乎相等。种群数量为41.1796万只。在45种珍稀水禽中,IUC红皮书水禽23种,8 247只;中国红皮书水禽22种,3 615只;CITES濒危水禽23种,40.631 6万只;国家重点保护水禽24种,3 838只。角等11种水禽未发现,可能已绝迹或极度濒危。按水禽1 %地理种群数量的标准,洪湖、沉湖、龙感湖、梁子湖、网湖等湿地可以确定为国际重要湿地。  相似文献   

4.
A total of 107 macrolepidopteran species from 12 families have been recorded in 2006–2010 on trees and shrubs in the city of Yekaterinburg; in contrast to natural communities, no lasiocampids and few nymphalids have been found. The proportion of specialized species among the Macrolepidoptera living in the city is decreased, although the proportion of obligate dendrophagous species is increased. Differences in the phenology of lepidopterans living in urban greenery from those living in natural communities have been observed: a decreased proportion of autumn-spring species and an increased proportion of summer species. These differences can be explained both by relatively weak colonization of urban territory by facultative dendrophagous species with their specific seasonal strategies and by differences in methods used to collect the insects.  相似文献   

5.
This paper reviews the current knowledge on the toxicity, speciation and biogeochemistry of arsenic in aquatic environmental systems. The toxicity of arsenic is highly dependent on the chemical speciation. The effects of pH, Eh, adsorbing surfaces, biological mediation, organic matter, and key inorganic substances such as sulfide and phosphate combine in a complex and interwoven dynamic fashion to produce unique assemblages of arsenic species. The number of different arsenic species found in environmental samples and an understanding of the transformations between arsenic species has increased over the past few decades as a result of new and refined analytical methods. Changes in arsenic speciation and in total arsenic content of foods upon processing have suggested possible risks associated with processed and unprocessed food. Arsenic removal from water using adsorbents, chemical oxidation, photolysis and photocatalytic oxidation techniques is also reviewed.  相似文献   

6.
In the Segara Anakan lagoon, Java, 21 tree species and 5 understorey genera have been identified. Average tree density is 0.80 ± 0.99 Ind./m2 with 48.71% seedlings and an average basal area of 9.86 ± 10.54 cm2/m2. Tree density and diversity are high in the eastern part of the lagoon, located near the city of Cilacap. There, the dominant tree species are Aegiceras corniculatum, Nypa fruticans and Rhizophora apiculata, of which the two latter are characteristic for mature forests. By contrast, understorey species and the pioneer species (Avicennia alba, Aegiceras corniculatum and Sonneratia caseolaris) dominate the central lagoon where several rivers discharge. Compared to former studies, seedling density and tree diameter in the central lagoon has declined considerably and tree species dominance has changed. The high sedimentation rates and deforestation are likely to prevent the formation of a mature forest there. Tree communities are more equilibrated in the eastern lagoon which points to a more stable and less disturbed mangrove forest.  相似文献   

7.
Climate change generally requires species to migrate northward or to higher elevation to maintain constant climate conditions, but migration requirement and migration capacity of individual species can vary greatly. Individual populations of species occupy different positions in the landscape that determine their required range shift to maintain similar climate, and likewise the migration capacity depends on habitat connectivity. Here, we demonstrate an approach to quantifying species vulnerabilities to climate change for 419 rare vascular plants in Alberta, Canada, based on a multivariate velocity of climate change metric, local habitat fragmentation, and migration capacity. Climate change velocities indicated that future migration requirements ranged from 1 to 5 km/year in topographically complex landscapes, such as the Alberta Foothills and Rocky Mountains. In contrast, migration requirements to maintain constant climate in relatively flat Boreal Plains, Parkland, and Grassland ranged from 4 to 8 km/year. Habitat fragmentation was also highest in these flat regions, particularly the Parkland Natural Region. Of the 419 rare vascular plants assessed, 36 were globally threatened (G1–G3 ranking). Three globally threatened species were ranked as extremely vulnerable and five species as highly vulnerable to the interactions among climate change velocity, habitat fragmentation, and migration capacity. Incorporating dispersal characteristics and habitat fragmentation with local patterns in climate change velocity improves the assessment of climate change threats to species and may be applied to guide monitoring efforts or conservation actions.  相似文献   

8.
Climate change is expected to cause shifts in species distributions worldwide, threatening their viability due to range reductions and altering their representation in protected areas. Biodiversity hotspots might be particularly vulnerable to climate change because they hold large numbers of species with small ranges which could contract even further as species track their optimal habitat. In this study, we assessed the extent to which climate change could cause distribution shifts in threatened and range-restricted birds in Colombia, a megadiverse region that includes the Tropical Andes and Tumbes-Choco-Magdalena hotspots. To evaluate how climate change might influence species in this region, we developed species distribution models using MAXENT. Species are projected to lose on average between 33 and 43 % of their total range under future climate, and up to 18 species may lose their climatically suitable range completely. Species whose suitable climate is projected to disappear occur in mountainous regions, particularly isolated ranges such as the Sierra Nevada de Santa Marta. Depending on the representation target considered, between 46 and 96 % of the species evaluated may be adequately represented in protected areas. In the future, the fraction of species potentially adequately represented is projected to decline to 30–95 %. Additional protected areas may help to retain representativeness of protected areas, but monitoring of species projected to have the largest potential declines in range size will be necessary to assess the need of implementing active management strategies to counteract the effects of climate change.  相似文献   

9.
2012年3月、6月、9月和12月按季度对涪江支流老河沟的14个样点进行了鱼类群落结构调查和分析。共采集鱼类11种,隶属于2目4科;其中,鲤形目鱼类7种,占物种数的63.64%。沿上游源头到下游的纵向梯度方向,老河沟鱼类的种类数和丰度均逐渐增加,具极显著性差异,而鱼类种类数和丰度则无季节差异性。聚类分析(Cluster Analysis)和多维尺度分析(MDS)表明,当Bray-curtis相似度矩阵值为40.77%时,老河沟鱼类群落分成上游、中游和下游3组。利用相似度百分比分析(SIMPER)确定,引起3组差异性的特定鱼类是宽鳍鱲、尖头、似()、齐口裂腹鱼、贝氏高原鳅、红尾荷马条鳅和青石爬鮡。典型相关分析(CCA)表明海拔、底质类型、流速、溶氧、总溶解固体、水温、电导率、河宽、pH值和水深等环境变量是老河沟鱼类群落时空格局差异的影响因子。  相似文献   

10.
The present study were made to estimate the avian fauna in terms of species richness and diversity and guild structure in forest habitats of Nainital district of Uttarakhand (350–2.450 m asl; 29° N). Field studies were conducted during January 2007 to December 2008. Total 43, 62 and 42 species were recorded from, Haldwani, Bhowali and Nainital forest habitats. Results indicate the species relationship between Bird species richness (BSR) and elevation sections (forest habitats) was not decline simultaneously along elevation; it shows hump shaped. BSR varied considerably along elevational gradient (43 to 62 species), was highest (62 species) at mid elevation (Mixed pine forest, 1.350–1.700 m asl) and decreased (20 species) at high elevation (Conifer forest, 1900–2450 m asl). It seems that mid altitude bulge is not caused by the presence of a group of mid altitude specialists but rather that there is an overlap in the distribution of low land and high elevation specialists at this altitude. A checklist of 79 avian species has also produced of Nainital district forest habitats. It is suggested that this study provide a base line structure for further study on species distribution in different forest habitats and along different elevation section in Western Himalayas (India).  相似文献   

11.
鄱阳湖子湖“堑秋湖”渔业资源结构特征分析   总被引:1,自引:0,他引:1  
"堑秋湖"是广泛存在于鄱阳湖湖区且与鄱阳湖水文节律特征相顺应的一种渔业方式。为了解"堑秋湖"渔获物组成特征及其产量与水位之间的关系,于2011~2013年"堑秋湖"期间对江西鄱阳湖国家级自然保护区的子湖大湖池和沙湖进行了连续3年的渔业调查。2011年,大湖池和沙湖与修河分别相通23d和10d,鄱阳湖属旱涝急转气候;2012年鄱阳湖水势较大,大湖池和沙湖与修河分别相通124d和108d。2013年鄱阳湖再现旱情,大湖池和沙湖均未能与修河连通。2011年渔业调查开展7次,2012年调查9次,2013年调查5次。3a调查累计获得鱼类59种隶属于6目12科43属。3年研究结果表明渔获物以鲤科鱼类为主,在种类上变化不大但优势物种有所改变且渔获物产量呈下降趋势,无度量多维排序结果(MSD)显示鱼类群落在不同年度和子湖间分离明显。经济鱼类的单位捕捞努力量(CPUE)与水位变化的线性回归分析结果表明,2011年经济鱼类产量与当日水位呈正相关性,但2012年和2013年两者的相关性却不明显。  相似文献   

12.
A field survey of herbaceous growing on lead-zinc mining area in Yunnan, China were conducted to identify species accumulating exceptionally large concentrations of Pb, Zn and Cd in shoots. In total, 220 plant samples of 129 species of 50 families and 220 soil samples in which the plants were growing were collected. According to accumulation concentration in plant shoots and the concentration time levels compared to plants from non-polluted environments, 21 plant samples of 16 species were chosen as best-performing specimens, 11 plant samples of 10 species for Pb, 5 plant samples of 4 species for Zn and 5 plant samples of 5 species for Cd. Sonchus asper (L.) Hill in Qilinkeng had hyperaccumulation capacity to Pb and Zn. Corydalis pterygopetala Franch in Paomaping had hyperaccumulation capacity to Zn and Cd. All 5 Cd hyperaccumulators came from Lanping lead-zinc mining area. Out of 11 Pb hyperaccumulators, 7 came from Minbingying of Huice lead-zinc mining area. The average of the concentration time levels compared to plants from non-polluted environments were higher than 10 times in all plant samples, the concentration time levels changed from 203 times to 620 times for Pb, from 50 times to 70 times for Zn and from 145 times to 330 times for Cd. Out of 21 plant samples, translocation factor changed from 0.35 to 1.90, only translocation factor of 7 plant samples were higher than 1. Enrichment coefficients of all samples were lower than 1. These plant species were primarily heavy metal hyperaccumulator, and will be used in phytoremediation of the metallic pollutants in soils after further research in accumulation mechanism.  相似文献   

13.
资源是区域经济发展的基础,资源结构是区域产业结构赖以形成的重要条件。区域产业是经济发展的载体,它不仅支持着区域的增长,而且在很大程度上决策着经济增长的能力与潜力。据此,在分析湖南省资源及产业结构优化标准的基础上,提出了充分与合理利用资源的产业对策建议。  相似文献   

14.
The levels of organohalogenated contaminants, such as organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were measured in four fish species (Acanthobrama marmid (kalashpa), Cyprinus carpio (carp), Chondrostoma regium (nose-carp), and Silurus glanis (wels)) from the Sir Dam Lake, Kahramanmaras, Turkey. These species were selected for their characteristic feeding behaviour and their importance to local human fish consumption. DDTs were the predominant organohalogenated contaminants in all species, with the p,p'-DDE contributing to more than 90% to the total DDTs. Other OCPs, such as hexachlorocyclohexane (HCH) isomers, chlordanes and hexachlorobenzene (HCB) were found at much lower levels in all five species. The levels of PCBs and PBDEs (on wet weight basis) were lower than in similar species from European or American freshwater systems. PBDE data were measured for the first time in fish species from Turkish environment. Lipid-based concentrations of OCPs, PCBs and PBDEs were higher in wels than in the other species and this was related to its piscivorous feeding mode and to its higher lipid content. Contrarily, concentrations of pollutants in nose-carp were the lowest, in agreement with its more herbivorous diet. A preferential accumulation in muscle compared to liver was observed for all OCPs, PCBs, and PBDEs in wels and carp, while in nose-carp, a preferential accumulation in liver was observed only for PBDEs, p,p'-DDT and PCBs. Racemic amounts for alpha-HCH were measured in all investigated muscle and liver samples, except for carp muscle.  相似文献   

15.
Setting out from Jacques Derrida’s assertion that every act of naming is “a foreshadowing of mourning” ([2008. The animal that therefore I am. (M.-L. Mallet, Ed., D. Wills, Trans.). New York, NY: Fordham University Press], p. 20), this paper argues that the work of earthly coexistence is underwritten by the intertwined practices of naming and mourning. The paper demonstrates that names provide access to and shape our perceptions of earthly entities; that the act of naming prepares us for the work of mourning; that the proper names given to endlings provide poignant points of access to species on the edge of extinction; that species names disclose species as such and, thus, enable us to grieve not just particular living organisms but entire ways of life; and that the name given to the current geological epoch, the “anthropocene,” simultaneously reflects and engenders a mode of awareness which enables us to relinquish those ways of being human that no longer seem sustainable and carry forth those that promise to enrich earthly coexistence.  相似文献   

16.
Data on the parasite fauna of the least cisco, Coregonus sardinella Valenciennes, 1848 in Ural tributaries of the Ob downstream of the city of Salekhard have been obtained for the first time. The formation patterns of the parasite fauna in this species and the rate (prevalence and intensity) of infection by Ichthyocotylurus erraticus (Odening, 1969), a parasite specific to coregonids, have been revealed. Infection of the least cisco with six parasite species (out of the 12 species found) occurs as the fish feed on zooplankton and benthic organisms. The dominant parasites are trematode larvae of the genera Ichthyocotylurus and, in some years, Diplostomum; this composition of dominants is evidence that the least cisco fattens up mainly in shallow areas. All sexually mature fish of this species were found to be infected by I. erraticus, but the average intensity of infection was rather low: the abundance index of the parasite did not exceed 40 ind. per fish. Analysis of the distribution of I. erraticus metacercariae in the least cisco shows that the relationship in the host-parasite system is stable and the parasite has no pathogenic effect on individuals of older age classes.  相似文献   

17.
The structural-temporal organization of a murine rodent community in the taiga has been studied near Lake Teletskoe, Mountain Altai. The results show that the long-term dynamics of indices characterizing community diversity depend mainly on changes in the structure of dominance rather than on the population dynamics of species. The distribution of species in the factor space corresponds to their preference for certain biotopes, from dry to relatively moist. An analysis of relationships within the rodent community has revealed the synchronous dynamics of species abundance and antiphase pattern of changes in the structural indices of dominant species.  相似文献   

18.
韩国南汉河的浮游植物及营养水平   总被引:4,自引:0,他引:4  
对韩国南汉河的浮游植物进行了周年的调查,结果显示,该河浮游植物的种类组成以绿藻为主,占总种类数的51.4%,其次为硅藻和蓝藻,分别占总种类数的26.7%和12.4%,其它4门藻类共计仅发现10种,占9.5%。细胞密度以蓝藻的贡献最大,占总细胞密度的36% ̄70.7%,绿藻次之,硅藻居第三位。相反,蓝藻的生物量却远不及硅藻和绿藻,硅藻对总生物量的贡献最高时可达93.7%。各站平均,浮游植物的细胞密度  相似文献   

19.
The abundance of Orchidaceae on three calcareous grasslands is studied in relation to floristic composition, environmental and vegetational factors and plant traits (ecological and life forms). The aims are: (i) to identify a group of species that is significantly correlated with the abundance of Orchidaceae or with individual species of orchids on calcareous grasslands; (ii) to study the relationship between traits associated with habitat specialisation, community life forms and the abundance of orchids; (iii) to identify the main environmental and vegetational predictors of the abundance of orchids. A shortlist of species is found to be significantly correlated with the abundance of total orchids, Orchis pauciflora and O. morio. The life forms of the community species do not show any correlation with the orchids, with the exception of Orchis pauciflora, which tends to increase in communities rich in hemicryptophytes and poor in annual species. Analyses of Orchis morio seem to suggest that it has a high level of ecological tolerance. The most important predictors of the abundance of orchids are the substrate reaction (basic) and arid grassland with low herbaceous vegetation cover (i.e. high soil reaction and luminosity values, positive correlation with the cover of lichens and rockiness, negative correlation with tree cover and herbaceous layer). The least favourable sites were the least basic and most superficial and arid sites.  相似文献   

20.
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