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1.
Thomas Wotte 《Facies》2009,55(3):473-487
Detailed litho- and biofacies investigations of the Lower–Middle Cambrian carbonate Láncara Formation resulted in its subdivision into nine lithofacies types: (1) claystone, (2) recrystallized mudstone, (3) laminated mudstone with laminoid-fenestral fabrics, (4) stromatolite, (5) laminated aggregate grainstone, (6) non-laminated aggregate grainstone, (7) oolitic-bioclastic floatstone, (8) echinodermal packstone, and (9) bioclastic grainstone. The thicknesses of lithofacies 1–7 (lower member of the Láncara Formation) decrease from south to north. Lithofacies types 8–9 (upper member of the Láncara Formation) are characterized by similar thicknesses and low facies and faunal gradients and are thus indicative of deposition on a carbonate ramp. From palaeoecological, palaeo(bio)geographical, palaeomagnetic, and tectonic considerations, the depositional environment of the Láncara Formation is re-interpreted as an eastward/north-eastward sloping, low morphology carbonate ramp. The Cantabrian Zone, with a primary lateral extension of about 300 km, is further construed to be an element of a widespread and connected, discontinuous drowned Perigondwanan depositional system.  相似文献   

2.
New sedimentological and paleontological information on the uppermost Moscovian and Kasimovian strata of the Las Llacerias section, a succession exposed in the Picos de Europa region (Cantabrian Mountains) that is considered to bear interest for the global correlation of the Upper Pennsylvanian subsystem, are presented. Based on sedimentological studies, three stratigraphic intervals can be established which record three successive episodes in the evolution of the carbonate platform. The study of the environmental evolution and sea-level fluctuations, as well as biostratigraphic fusulinoidean information, allow the correlation of this section with the synorogenic deposits of the Gamonedo-Cabrales area (northern Picos de Europa region). It is recognized that in the Las Llacerias strata, 7 of the 11 depositional sequences of the latter area are represented. The taxonomy and distribution of smaller foraminifers, a fossil group never studied before in this section, have been analysed. Data obtained show the presence of, at least, 30 genera. In some cases (Syzrania aff. bulbosa, Tezaquina, Mesolasiodiscus, Pseudotaxis and Hemidiscus), their record in the Las Llacerias section significantly extends the stratigraphic genus or species range. The potential role of Protonodosaria and Nodosinelloides species, as well as the acme of Hemigordius schlumbergeri for the correlation of the Kasimovian deposits is reinforced within this study.  相似文献   

3.
小岛屿效应描述了种-面积关系的一种特殊现象,是当前生物地理学和生物多样性研究理论框架的重要组成部分。随着气候变暖,山顶物种的生存受到威胁,然而以山顶生境岛屿为载体对小岛屿效应的研究还十分缺乏。该研究以太行山脉中段19个面积0.06–801.58km2的山顶生境岛屿为研究区,在2019–2021年的夏秋季对藓类进行调查。共记录到藓类131种,隶属于23科68属。采用6种种-面积关系回归模型,分别检测了所有藓和6个常见藓科是否存在小岛屿效应。根据小岛屿效应形成机制的生境多样性假说、灭亡假说和营养补给假说,选择了岛屿高度、温度年变化范围和单位面积净初级生产力作为变量,对小岛屿效应的驱动因素进行分析。在各类群组中,使用多元线性回归和变差分解分别评估上述3个变量对物种丰富度变化的线性影响。首先使用5个面积最小的岛屿进行分析,计算出3个变量对物种丰富度变化的贡献,然后以迭代的方式逐次加入面积更大的1个岛屿,并再次进行变差分解分析。最后使用广义线性回归分析了3个变量对物种丰富度变化的贡献在迭代过程中的变化趋势。结果显示,所有藓和6个常见藓科均存在小岛屿效应,其面积阈值分布在0....  相似文献   

4.
Research on human evolution depends in many cases on the study of fossil remains that have been treated by conservators. Conservation is a discipline with its own principles and methods. Its goal is not only long-term preservation, but also information recovery and the facilitation of research. Therefore, specialists in conservation propose and carry out the interventions, while research requirements must act as a guide in many steps of the process. In this article, we present an example of a strict conservation methodology applied to a human mandible from the Pleistocene site of Gran Dolina (Sierra de Atapuerca, Spain). An extensive diagnostic examination before the intervention included a computer tomography (CT) scan and stereoscopic light microscopy. This paper describes both the intervention and the mechanical preparation in detail. Finally, the intervention is discussed, as well as general conservation techniques. The compiled details show how this interdisciplinary work allowed retention of both the integrity of the specimen and its information. In conclusion, the development of a suitable method of conservation requires collaboration among all the specialists involved in the study of fossil remains.  相似文献   

5.
To restore the human-disturbed natural ecology and to assess the impact of the projected future climatic change on the natural ecology at a plant community level or at a plant species level, we need to understand the potential distribution of the community or the species under current climate conditions. Many methods have recently been developed to simulate the potential distribution of a particular community or a particular species, but very little has been done to assess the potential distribution of Qinghai spruce (Picea crassifolia) in Qilian Mountains where the spruce forests are extremely important ecologically and hydrologically. This study used maximum entropy model to simulate the potential distribution of Qinghai spruce under current climate conditions and the validity of the model was verified by statistically comparing the simulated potential distribution with the observed actual distribution of the spruce. We then applied this verified model to assess the impact of the projected future climatic changes on the spruce and the simulated results show that the areal extent of the potential distribution of Qinghai spruce may increase by 1% under the projected future climate change scenario. In addition, this study revealed that among the 19 environmental and climatic factors used in this model, the most important factors are the mean maximum temperature in the warmest month and the mean temperature of the wettest quarter in controlling the potential distribution of Qinghai spruce, these two factors accounting for as much as 75.6% of the variations.  相似文献   

6.
The purposes of this article are to quantify the relationship between epiphytic lichen distribution and macroclimatic variables in the study area and to provide a case study for evaluating the predictive role of epiphytic lichens as bioclimatic indicators. The study was carried out in the Liguria region (NW-Italy), a small (5432 km2) borderline area, where phytoclimatic features range from the dry Mediterranean to the Alpine in a few kilometers. Epiphytic lichen diversity was sampled using a standardized protocol [Asta et al (2002) In: Nimis et al (eds) Monitoring with lichens: monitoring lichens. Kluwer, Dordrecht]. Abundance of the species in the sampling sites was related to macroclimatic parameters (yearly average temperature and rainfall) and non-parametric multivariate models were calculated to find significative relationships among predictive and response variables. A total of 59 species showed highly significant relation with macroclimatic parameters. Four groups were selected, by means of a cluster analysis, related to four climatic niches (warm-humid, cold-humid, mesothermic-humid, warm-dry). Distributional pattern of the groups in the survey area showed a good correspondence with the bioclimatic units of Liguria region described by Nimis [(2003) Checklist of the Lichens of Italy 3.0. University of Trieste, Dept of Biology. http://www.dbiodbs.univ.trieste.it. Cited 1 Jun 2006]. A significant subset of epiphytic lichen species in the study area have been proved to be efficient bioclimatic indicator and it is supposed to give good results to monitor climatic changes, in a long-term perspective.  相似文献   

7.
Xu Z L  Zhao C Y  Feng Z D 《农业工程》2009,29(5):278-285
To restore the human-disturbed natural ecology and to assess the impact of the projected future climatic change on the natural ecology at a plant community level or at a plant species level, we need to understand the potential distribution of the community or the species under current climate conditions. Many methods have recently been developed to simulate the potential distribution of a particular community or a particular species, but very little has been done to assess the potential distribution of Qinghai spruce (Picea crassifolia) in Qilian Mountains where the spruce forests are extremely important ecologically and hydrologically. This study used maximum entropy model to simulate the potential distribution of Qinghai spruce under current climate conditions and the validity of the model was verified by statistically comparing the simulated potential distribution with the observed actual distribution of the spruce. We then applied this verified model to assess the impact of the projected future climatic changes on the spruce and the simulated results show that the areal extent of the potential distribution of Qinghai spruce may increase by 1% under the projected future climate change scenario. In addition, this study revealed that among the 19 environmental and climatic factors used in this model, the most important factors are the mean maximum temperature in the warmest month and the mean temperature of the wettest quarter in controlling the potential distribution of Qinghai spruce, these two factors accounting for as much as 75.6% of the variations.  相似文献   

8.
Species Distribution Models (SDMs) may provide important information for the follow-up phase of reintroduction operations by identifying the main areas most likely to be colonized by the reintroduced species. We used SDMs to identify the potential distribution of Eurasian beavers (Castor fiber) reintroduced to Serbia and Bosnia and Herzegovina in 2004–2006 after being historically driven to extinction by overhunting. Models were also used to carry out a gap analysis to assess the degree of protection granted by the national reserve networks to the potentially expanding population. Distances from hydrographic network, broadleaved forest, main watercourses and farmland were the main factors influencing model performance. We estimated that suitable habitat covers 14.0% (31,000 km2) of the whole study area. In Serbia, in 2004–2013 beavers expanded their range at a mean colonization speed of 70.9 ± 12.8 km/year (mean ± SD). Only 2.89% of and 9.72% of beaver’s suitable habitat lie within the national network of protected areas of Bosnia and Serbia respectively. We detected new potential areas where beavers will likely settle in the near future, advising on where further monitoring should be carried out. We also identified low suitability areas to be targeted with appropriate management to improve their conditions as well as important regions falling outside reserve boundaries to which protection should be granted.  相似文献   

9.
提出了随时间变化的人类活动效应对物种多样性影响的多物种竞争非自治动力模式,并以洪湖为例模拟了湿地水鸟物种多样性对人类活动效应(生境持续毁坏)的响应过程。模拟发现:对于强.强物种,生境的持续破坏使得湿地水鸟的物种多度大幅度减小,并发生优势种群的更替;对于弱-弱物种,将导致大批的弱物种种群迅速灭绝,而余下的弱物种种群将做准周期振荡;尽管停止对湿地生境的持续毁坏,仍会使一批弱物种种群继续走向灭绝,并且使得原来最强的几个种群最终灭绝。物种灭绝对生境毁坏的这种时间滞后性,即破碎的生境中存在着一些“活死者”,必须引起自然保护学家的关注,否则会低估了实际处于灭绝边缘的物种的数目,从而影响正确的物种保护决策的制订。  相似文献   

10.
Leveraging existing presence records and geospatial datasets, species distribution modeling has been widely applied to informing species conservation and restoration efforts. Maxent is one of the most popular modeling algorithms, yet recent research has demonstrated Maxent models are vulnerable to prediction errors related to spatial sampling bias and model complexity. Despite elevated rates of biodiversity imperilment in stream ecosystems, the application of Maxent models to stream networks has lagged, as has the availability of tools to address potential sources of error and calculate model evaluation metrics when modeling in nonraster environments (such as stream networks). Herein, we use Maxent and customized R code to estimate the potential distribution of paddlefish (Polyodon spathula) at a stream‐segment level within the Arkansas River basin, USA, while accounting for potential spatial sampling bias and model complexity. Filtering the presence data appeared to adequately remove an eastward, large‐river sampling bias that was evident within the unfiltered presence dataset. In particular, our novel riverscape filter provided a repeatable means of obtaining a relatively even coverage of presence data among watersheds and streams of varying sizes. The greatest differences in estimated distributions were observed among models constructed with default versus AICC‐selected parameterization. Although all models had similarly high performance and evaluation metrics, the AICC‐selected models were more inclusive of westward‐situated and smaller, headwater streams. Overall, our results solidified the importance of accounting for model complexity and spatial sampling bias in SDMs constructed within stream networks and provided a roadmap for future paddlefish restoration efforts in the study area.  相似文献   

11.
For many insect species, egg and larval substrate characteristics are significantly correlated with interspecific differences in female reproductive allocation and egg size-number tradeoffs. We tested the hypothesis that a similar pattern occurred within the Australian drosophilid, Drosophila hibisci, that is restricted throughout its life cycle to flowers of species in the genus Hibiscus. These plants occur as small, isolated, normally monospecific stands that should facilitate differentiation of the fly populations in relation to specific oviposition and larval substrates. Data from 38 sites ranging from 20.8̀ to 34.4̀ S latitude in eastern Australia indicated no relationship between female body size, egg size, or ovariole numbers and floral size or mass among four species of Hibiscus. However, the flies did show a latitudinal cline in ovariole number that was independent of floral variation. Females averaged 15–20 ovarioles per female in the south (32–34̀ S latitude) and 10–12 ovarioles in the north (21–22̀ S latitude). The increase in ovariole number with latitude was due to divergence in the ovariole number of the largest females. In contrast, small females in the north and south had the same number of ovarioles. Reproductive allocation of female flies in the northern region was less than females in the southern region. The latitudinal divergence in ovariole number was not associated with habitat differences (density of trees, density of flies and beetles), nor with differences in floral characteristics (flower weight, petal length, yeast species present). Short term weather patterns in daily temperature and rainfall preceding collections pardy explain the variation in ovariole number. These observations in conjunction with preliminary genetic results suggest the cline is associated with genetic differences that interact with environmental determinants such as the temperature during larval development.  相似文献   

12.
In order to emphasize the importance of vegetation mapping for nature conservation purposes a case study in Terceira island (Azores) is presented, in which the importance of the natural vegetation of the eastern slope of Santa Bárbara volcano (which is part of the Site of Community Importance of Santa Bárbara–Pico Alto) is evaluated through the elaboration of its vegetation map. Fourteen (14) different natural vegetation types were identified: grasslands (1 type), peat bogs (2 types), scrubs (2), forests (5), successional vegetation (3) and vegetation of rocky slopes (1). All communities are protected under the Habitat and Species Directive (EC/92/43) and most of them are endemic to the Azores Islands. This fact, together with the significant number of Azorean endemic taxa (18), Macaronesian endemic taxa (5) and species protected under the Habitat and Species Directive (7), gives this area an important conservation value that justifies future protection actions. Vegetation mapping is an important tool for the characterization, evaluation and implementation of managing plans of natural areas of the Azores islands. The use of a floristic-based classification, supported by multivariate analysis and structural data, is an efficient methodology for the construction of these maps. The data collected comprise an important set of information about the distribution and abundance of natural vegetation types and endemic and rare species. This information was not available until now and is indispensable for the elaboration of management plans of Special Zones for Conservation that will be part of the NATURA 2000 network.  相似文献   

13.
We studied the habitat of the polecat at different scales in a low density area. For this purpose we gathered data on the presence of the species and characterised them by location, home range and landscape scales. Polecats selected areas of high diversity close to, but not in, streams whilst avoiding intensively managed conifer plantations and dense urban areas. Variables determining the presence/absence of the species were found at home range scales, which implies that management and conservation practices for the species should be aimed mainly at this scale. Finally, our results agree with previously published works, which validate GIS-based approaches as a tool for carnivore management in areas with scarce data or in cases of rare species.  相似文献   

14.
Four congeneric species of pelagic copepods (Acartia margalefi,A. clausi, A. discaudata and A. grani) coexist in the r?a ofVigo, an estuary located on the NW Spanish coast. There is apartial segregation of the species along the axis of the r?a,their respective abundances decreasing exponentially from thezones of maximum densities. A. margalefi and A. grani have beenfound exclusively in the inner part of the r?a, while A. clausiis more abundant in the external zones, and A. discaudata occupiesan intermediate area. Temperature and salinity gradients seemto have less importance than the spatial differences in stability(in the sense of persistence of environmental factors) as determiningthe species segregation.  相似文献   

15.
Xiang ZF  Huo S  Xiao W  Cui LW 《动物学研究》2010,31(6):645-650
黑白仰鼻猴(Rhinopithecus bieti)是仅存于滇西北和藏东南的横断山脉的濒危灵长类动物,目前仅有野外15群约2500只个体,并且西藏红拉雪山自然保护区的小昌都群也许是自1988年调查以来唯一数量保持稳定的种群。通过调查访问、以及分析社会经济数据中隐含的保护信息,该文通过实例研究探讨了传统文化和社会经济发展模式对红拉雪山自然保护区小昌都猴群的影响,试图探讨传统文化和人类活动对该猴群种群保持稳定的正面影响:1)研究结果表明传统的生产方式对黑白仰鼻猴的生境保护有益,例如主要依靠畜牧业和非木材的林产品而不是毁林开荒种植青稞;2)受印度教和佛教影响的藏传佛教对生灵的敬畏,避免当地村民对黑白仰鼻猴的猎杀;3)一妻多夫的大家庭,其人均资源消耗(特别是薪柴,建房木材等)明显比一夫一妻的小家庭少,这种婚俗也许可以缓解人类索取相应自然资源时对黑白仰鼻猴的生境破坏。因此,考虑到小昌都是唯一种群稳定的群,我们认为是当地的社会生产方式、宗教文化以及婚俗习惯让小昌都群长期维持在该生境的最大容纳量。  相似文献   

16.
Three endemic Cretan land snail species of the genus Mastus (Beck, 1837) from the island group of Koufonisi (south-east Crete) and the eastern part of Crete, were studied by multivariate analysis of shell morphology and analysis of mtDNA sequences. The phylogeny of the populations studied and the processes effecting the genetic and morphological diversity of the species were investigated. Extremely high mtDNA sequence divergence was observed both within and between populations. The Cretan populations could not be distinguished morphologically, while the populations of the islets were more distinct. We argue that the active geological past of the area (including sea level changes) and the long-term presence of humans has produced a mixing up of Mastus populations leading to the accumulation of high divergence of mtDNA sequences on a small spatial scale. The limited morphological diversity and the distinct shell 'identity' of the islets' populations can be attributed to the selective pressures of the island group.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78, 383–399.  相似文献   

17.
Many habitat patches in tropical landscapes have become less suitable for wildlife due to an increase in anthropogenic disturbances. An index of habitat suitability based on the ecological factors that collectively determine the suitability of an organism's habitat is important for conservation planning. However, a widely accepted and comprehensive multi-criteria habitat suitability index for umbrella species is still lacking, particularly in areas where information related to the biology and ecology of the species of interest is not available. Therefore we develop preliminary habitat maps and measure the degree of habitat suitability for large mammals, focusing on four umbrella species in the State of Selangor, Peninsular Malaysia: Panthera tigris jacksoni (Malayan tiger), Tapirus indicus (Malayan tapir), Helarctos malayanus malayanus (Malayan sun bear), and Rusa unicolor cambojensis (sambar deer). The former two are endangered and the latter two are vulnerable according to the IUCN Red List. The suitability of habitat patches for each species was measured across the entire study area as well as in nine wildlife protected areas by integrating GIS data and expert opinion. Expert opinions were used as the source of information regarding the stresses faced by the species because there was insufficient information available from ground surveys.We developed an index and maps of habitat suitability for each species, which were then integrated to represent a combined index (ranging from 0 to 27) and spatially explicit maps of the area's habitat suitability for large mammals. The average large mammal habitat suitability index value of the State of Selangor (9) indicates that many habitat patches have become unsuitable for such species. Of the nine wildlife protected areas, Fraser's Hill (22), Sungai Dusun (22), and Bukit Kutu (21) are very suitable; Klang Gate (20) and Templers Park (17) are suitable; and the remaining four are unsuitable for large mammals. We assume that this preliminary habitat suitability index and mapping are useful for conservation planning of wildlife habitats at both landscape and regional scales, as well as providing an initial foundation for revision by future research with significant new information.  相似文献   

18.
《植物生态学报》2021,44(11):1113
全球变化背景下的干旱区植被变化受气候变化和人类活动双重影响。定量评价植被变化特征及其驱动机制, 对监测干旱区区域生态环境变化, 促进区域可持续发展有重要意义。由于复杂多样的人类活动难以量化, 有关这方面的研究多局限于植被对气候变化的响应, 而对人类活动影响考虑不足, 导致关于这方面的认识存在较大的偏差和不确定性。该文首先提出与土地利用相关的人类活动量化表征方法; 然后运用多元线性回归模型和随机森林模型中的较优模型, 分析气候变化和具体的人类活动对北天山北坡中段归一化植被指数(NDVI)的影响。主要结果: (1) 2000-2015年期间北天山北坡中段年NDVI总体呈增加趋势; 基于随机森林构建的NDVI与气候因子和人类活动的模型拟合精度明显优于多元线性回归模型, 其决定系数(R2)至少提高了24%; (2)研究期内与耕地有关的人类活动对北天山北坡中段NDVI分布及时空变化的影响呈增加的特征, 在2000-2015年期间人类活动对NDVI变化的贡献率为0.59, 超过了气候因子。该项研究为气候变化和人类活动对植被的影响研究提供了新思路, 也为干旱区生态环境保护和恢复提供了科学依据。  相似文献   

19.
The aim of this work was to investigate a very common situation in the archaeological and anthropological context: the study of a burial site containing several individuals, probably related genetically, using ancient DNA techniques. We used available ancient DNA and forensic protocols to obtain reliable results on archaeological material. The results also enabled molecular sex determination to be compared with osteological data. Specifically, a modified ancient DNA extraction method combined with the amplification of nuclear markers with the AmpFlSTR®MiniFiler? kit(Applied Biosystems) was used. Seven medieval individuals buried in four niches dated in the 15th Century at San Esteban Church in Cuellar (Segovia, Central Spain) were analyzed by the proposed method, and four of seven provided complete autosomal short tandem repeat (STRs) profiles. Kinship analyses comprising paternity and sibship relations were carried out with pedigree‐specific software used in forensic casework. A 99.98% paternity probability was established between two individuals, although lower percentages (68%) were obtained in other cases, and some hypothetical kinship relations were excluded. The overall results could eventually provide evidence for reconstructing the historical record. Am J Phys Anthropol, 2011. © 2010 Wiley‐Liss, Inc.  相似文献   

20.
利用九寨沟自然保护区内8条动物监测样线在2003—2010年的生态监测数据,分析了植被、海拔、人为干扰对大中型野生动物分布的影响,结果显示:1)本监测共记录到保护区内大中型野生动物26种,其中兽类18种,鸟类8种,属于我国Ⅰ级、Ⅱ级保护动物的分别有5种和11种。2)针阔混交林和针叶林是大中型野生动物种类最丰富的两种植被类型(分别有26种和17种),阔叶林和灌丛次之(分别为10种和12种),草地最少(2种)。3)海拔2400 m以下的地方,大中型野生动物种类稀少,为10种,2400—2599 m海拔段物种数增加至20种,之后随海拔上升物种丰富度下降。4)人为干扰显著影响大中型野生动物的空间分布:历史上的人类活动将原生森林植被转化为次生的落叶阔叶林、灌丛和草地,使树正、亚纳和尖盘等地下坡位(相对海拔0—199 m)的大中型野生动物的物种丰富度降低(分别为4、2、2种)。包括旅游活动和交通在内的人为干扰,可能导致附近50m海拔范围内保护动物的缺失,并使下坡位的某些物种向高海拔处移动。生境破碎化则使野生动物的种类组成发生改变,使原有森林内部优势种,如羚牛(Budorcas taxicolor),逐渐被适应能力强的物种,如豹猫(Prionailurus bengalensis)、雉鸡(Phasianuscolchicus)和野猪(Sus scrofa)等所取代,并将长期影响野生动物种群的存活。当前九寨沟自然保护区大中型野生动物的分布是植被、海拔与人为干扰综合作用的结果。  相似文献   

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