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1.
The draining of mires for silvicultural purposes has caused one of the most dramatic changes in the landscape during the last century in Finland. To study the effects of mire drainage, carabid beetle assemblages were sampled using pitfall trapping in three different mire habitat types. Carabids were sampled from mires in their natural state, drained mires and drained mires with an open power line to see whether the cleared power line can serve as an alternative habitat for mire dependent carabids. The draining of mires greatly increases the species richness of the carabid assemblages. Yet, the conservation value of the environment has dropped following the draining, since only common and abundant forest carabids have benefited from human impact. The role of the open power line as an alternative habitat for mire specialists remains questionable. A few carabid species have, however, benefited from the open habitat of the power line. The vegetation structure had a significant effect in determining the compositions of the carabid assemblages on the studied habitat types. It seems that mire dwelling carabids cannot survive on the drained mires, unless at least some characteristics, other than the mere openness of the cleared power lines, of natural mires remain.  相似文献   

2.
Palynological analysis of the organic contents of ceramic pots from the Kodiani burial mound, which is dated as 27th-25th centuries B.C., revealed that they contained honey. The samples are extremely rich in excellently preserved pollen grains, including numerous pollen grains of insect-pollinated plants. Such characteristics are typical of palynological assemblages from honey. The palynological assemblages from three pot fragments studied are dominated by pollen grains of Rosaceae; however, they differ from one another in the subdominants. The discovery of several kinds of honey testifies to the presence of well-developed beekeeping in the time of the Early Kurgans. Agriculture, with a significant role of wheat, was also developed in the region of Georgia under study. According to the composition of the palynospectra, the ecological conditions that existed during the epoch studied differ significantly from the present day.  相似文献   

3.
传统观念认为GSPD组合始于中二叠世孔谷期,据新疆等地资料证实此类组合的出现要早得多。准噶尔盆地在Profosulinella-Pseudostaffella带之下和相当层位的晚石炭世早期地层中存在两个孢粉组合,即(1)早巴什基尔期巴塔玛依内山组的Remysporitesvaricus-Striatolebachiitesjunggarensis组合(Pro-GSPD)和(2)中晚巴什基尔期-早莫斯科期车排子组的Protohaploxypinusverrucosus-Hamiapolleniteschepaiziensis组合(GSPD)。结合以往在乌拉尔东、西坡,加拿大北极群岛和育空地区的记载,论述了这些大体同时代GSPD组合在植物地理、古生态和生物地层对比上突破传统观念的重大意义,指出亚安加拉区起源很早,随着欧亚大陆的北移和半干旱气候带的扩张,某些亚安加拉植物成分可能发生过向南的迁移。  相似文献   

4.
《Palaeoworld》2019,28(3):346-360
The palynological and macrofloral assemblages from the Lower Member of the Ukurey Formation have been studied based on the materials from a section exposed along the Kulinda Ravine (Olov Depression, Transbaikalia). This section is of special interest due to the occurrence of ornithischian dinosaurs. Based on palynological and palaeobotanical data, the studied deposits are dated as Middle Jurassic (Bathonian). Specific features of the palynological assemblages allow the correlation of the studied interval with Western Siberian palynozones calibrated by ammonite and foraminiferal successions. The resulting biostratigraphy suggests that the lower extent of the Ukurev Formation is not restricted to the Upper Jurassic as previously assumed. Lacustrine origin of the Lower Member of the Ukurev Formation is confirmed based on palaeoenvironmental analysis, showing changes of the terrestrial vegetation, associated with climatic conditions and fluctuations of the lake-level. Palaeobotanical and palynological data suggest that Middle Jurassic floras of eastern regions of Central Asia, southern regions of Siberia and Far East, as well as northern regions of China exhibit similar features.  相似文献   

5.
Palynological spectra were studied from piston-cores of bottom sediments in the southwestern part of the Sea of Japan and the East Korea Bay. Five palynological assemblages were revealed in the sediments of the deep core and three, in the shelf core. The palynological assemblages were formed during different climatic phases and reflect main stages in the development of the vegetation of the region. The Holocene optimum was determined for the southern coast of the Sea of Japan.  相似文献   

6.
《Palaeoworld》2008,17(2):135-141
Palynological assemblages were studied from the coal-bearing Upper Jurassic (Talanja Formation) to the Lower Cretaceous (Dublikan Formation) deposits of the Bureya Basin, Russia. The palynological assemblages from the upper part of the Talanja Formation are dominated by gymnosperms, mainly Ginkgocycadophytus (up to 40%) and conifers related to Pinaceae (up to 70%). The contribution of non-seed plants is not great, but their diversity is considerable. The miospore assemblages of the Talanja sequence are characterized by the last appearance of the spore taxa Staplinisporites pocockii, Camptotriletes cerebriformis, Camptotriletes nitida, and Cingulatisporites sanguinolentus. The palynological assemblage from the Dublikan Formation is dominated by ferns (up to 84%), represented mainly by Cyathidites and Duplexisporites. Among gymnosperms the role of Classopollis increases (making up about 20%). Another feature is the first appearance of the spore taxa Stereisporites bujargiensis, Neoraistrickia rotundiformis, Contignisporites dorsostriatus, Appendicisporites tricostatus, and Concavissimisporites asper.  相似文献   

7.
Apart from the few works carried out in the North Tethyan basins, the palynological study of Mesozoic outcrops is still rare. Thus, the present study devoted to the Zahra Marls Formation (upper Bajocian) of the Rhar Roubane Mountains (northwestern Algeria), allowed us for the first time to inventory 44 different taxa. The palynological assemblages studied are strongly dominated by trilete spores (17 genera and 26 species), the most abundant of which are Concavissimisporites variverrucatus, Cyathidites australis and Cyathidites minor. Pollen grains are relatively frequent (10 genera and 16 species), while acritarchs and algae are represented by only two taxa (Micrhystridium sp. and Botryococcus sp.). In addition, the sporopollinic spectra dominated by the terrestrial elements are represented mainly by the spores of Pteridophyta and Bryophyta and gymnosperm pollen.  相似文献   

8.
The end-Triassic mass extinction event (∼201.4 million years ago) caused major faunal and floral turnovers in both the marine and terrestrial realms. The biotic changes have been attributed to extreme greenhouse warming across the Triassic–Jurassic (T–J) boundary caused by massive release of carbon dioxide and/or methane related to extensive volcanism in the Central Atlantic Magmatic Province (CAMP), resulting in a more humid climate with increased storminess and lightning activity. Lightning strikes are considered the primary source of wildfires, producing charcoal, microscopically recognized as inertinite macerals. The presence of polycyclic aromatic hydrocarbons (PAHs) of pyrolytic origin and allochthonous charcoal in siliciclastic T–J boundary strata has suggested widespread wildfire activity at the time. We have investigated largely autochthonous coal and coaly beds across the T–J boundary in Sweden and Denmark. These beds consist of predominantly organic material from the in situ vegetation in the mires, and as the coaly beds represent a substantial period of time they are excellent environmental archives. We document a remarkable increase in inertinite content in the coal and coaly beds across the T–J boundary. We show estimated burning temperatures derived from inertinite reflectance measurements coupled with palynological data and conclude that pre-boundary late Rhaetian mire wildfires included high-temperature crown fires, whereas latest Rhaetian–Sinemurian mire wildfires were more frequent but dominated by lower temperature surface fires. Our results suggest a major change in the mire ecosystems across the T–J boundary from forested, conifer dominated mires to mires with a predominantly herbaceous and shrubby vegetation. Contrary to the overall regional vegetation for which onset of recovery commenced in the early Hettangian, the sensitive mire ecosystem remained affected during the Hettangian and did not start to recover until around the Hettangian–Sinemurian boundary. Decreasing inertinite content through the Lower Jurassic suggests that fire activity gradually resumed to considerable lower levels.  相似文献   

9.
The present paper provides preliminary palynostratigraphical data from the Hornos section, one of the characteristic sections of the Hornos—Siles Formation (Triassic of the Prebetic Zone), NE province of Jaén, Spain.Some remarks are made on the lithostratigraphical development of this formation and its tectonic complications. The palynological assemblages recognized are attributed to the scheme of successive phases in compositional development of palynological assemblages established for the late Middle—Late Triassic; the assemblages indicate a Ladinian—Karnian age for the formation.  相似文献   

10.
Successional sequences from forested wetlands in the Middle Atrato River Basin were reconstructed using characterisation of present vegetation communities and palynological analysis. A 4.8 km transect, drawn across a river meander, and two 6 and 8 m deep sediment cores (San Martín and Villanueva) were collected in the floodplain within two different vegetation assemblages. Based on the floristic and environmental characteristics of the local vegetation communities, ecological changes spanning the last 4 ka (cal years BP) were analysed in San Martín and Villanueva cores. Present vegetation is dominated by four communities determined by flood tolerance and drainage conditions. We found Euterpe oleraceae, Mauritiella macroclada-Campnosperma panamensis and Oenocarpus bataua forests, and mixed forest and open vegetation in a gradient from poor to improved drainage conditions. Vegetation changes in the palynological record suggest that sedimentation and erosion processes on flood basins are due to changes in drainage conditions and to variable flooding levels.A wet period in the 4 to 2.7 ka interval is postulated, which might be related to sea level rise or local subsidence. Lower flooding levels and improved drainage conditions dominated the 2.7 to ∼ 1.6 ka interval, whereas a flooding event (and a hiatus) occurred between 1.5 and 0.5 ka. This flooding event might be synchronous with analogous events as recorded in the Colombian Amazonia between 1.6 and 1.45 ka. Forest disturbance, probably of anthropogenic origin, is recorded in both sites since 0.5 ka.  相似文献   

11.
The Fuentelsaz Section is located in the Castilian Branch of the Iberian Range (Guadalajara, Spain). Its exceptional Lower-Middle Jurassic transition outcrops led to its designation as the Global Boundary Stratotype Section and Point for the base of the Aalenian. The sediments of the Toarcian-Aalenian transition at Fuentelsaz are composed of marls with interbedded limestones in rhythmic alternation. Marls are dominant in the Toarcian and the Opalinum Zone up to the middle part of the Comptum Subzone. In the remaining Comptum Subzone, marly materials are scarce and limestones predominate. Sedimentation at Fuentelsaz took place over an extensive marine epeiric carbonate platform that was well connected with the open sea. In the Fuentelsaz Section, a total of 43 palynomorph taxa were recorded: 23 spore taxa, 13 pollen taxa, 4 acritarchs, 2 prasinophytes and 1 dinoflagellate cyst. The studied sediment samples were always dominated by terrestrial allochthonous miospores. In general, miospore assemblages are biased due to the transport of pollen from land or islands to the continental platform. Spheripollenites, Classopollis or indeed both pollens numerically dominate the assemblages. Other miospores appear in low numbers. Aquatic palynomorphs are also scarce; Micrhystridium lymensis is the most common. Five palynological assemblages (PA) were distinguished: PA1, PA2 and PA3 are Toarcian in age, PA4 is located at the boundary between the Toarcian and the Aalenian and PA5. This latter palynological assemblage which is lower Aalenian in age shows a strong reduction in palynomorph diversity and preservation in the Comptum Subzone. Palaeoecological analysis of the palynomorphs indicated the presence of calm, oligotrophic sea water. The palaeofloral communities of gymnosperms and vascular cryptogams—which grew in subtropical arid conditions—were poorly diversified.  相似文献   

12.
通过对山东青东凹陷西部古近纪地层孢粉研究,共建立4个孢粉组合:Ⅰ.Ephedripites-Inaperturopollenites-Ulmipollenites minor,Ⅱ.Pinaceae-Ulmoideipites tricostatus-Taxodiaceaepollenites,Ⅲ.QuercoiditeshenriciTaxodiaceaepollenites hiatus,Ⅳ.Alnipollenites-Juglanspollenites-Polypodiaceaes porites。根据与渤海湾地区的孢粉资料对比,确定4个组合的时代分别为早始新世晚期—中始新世早期、中始新世早—中期、中始新世中—晚期、中始新世晚期—晚始新世。该区古近纪植被类型由落叶、阔叶和灌木混交林逐步转变为落叶、常绿阔叶和针叶混交林,古气候经历了干热的亚热带气候到湿热的亚热带气候再到亚热带型温暖气候的变化。沙四段上部到沙三段下部沉积时期是研究区烃源岩最为发育时期。  相似文献   

13.
Cyclical changes in microfossil (mainly foraminiferal) assemblages were analysed for sixteen boreholes from three stratigraphical levels in the Lower and Middle Miocene of the Central Paratethys. The following characteristics of assemblages were quantified and used for interpretation of cyclical changes in assemblages: (1) abundance of foraminifers, calcareous nannoplankton, sponge spicules and diatoms; (2) similarity, diversity and epifauna/infauna ratio of benthonic foraminiferal assemblages; (3) planktic/benthic ratio of foraminiferal assemblages. The palaeoecology (mainly palaeobathymetry) fluctuations were interpreted from the species composition of assemblages. Values of the mentioned quantitative characteristics as well as palaeoecological interpretations may be influenced by postmortem transport and resedimentation of foraminiferal tests. Therefore, prior to the interpretation of cyclical changes of quantitative characteristics, the studied sections were classified on the basis of the intensity of taphonomical changes in foraminiferal assemblages. Three different categories of sections were obtained. For every category, those quantitative characteristics of foraminiferal assemblages were chosen which reflect cyclical changes most efficiently: (1) cyclical changes of abundance of foraminifers, calcareous nannoplankton and sponge spicules, as well as the fluctuations in palaeobathymetry for sections dominated by indigenous foraminifers; (2) percentage of indigenous, suspension-transported, bedload-transported and reworked foraminiferal tests and changes in the abundance of indigenous tests for sections dominated by transported tests; (3) different modes of test preservation used for the identification of a cycle boundary for sections with only transported or reworked tests. The distinguished cycles were interpreted predominantly as manifestations of relative sea-level changes. If comparable data exist from other Paratethys regions, the determined cycles can be correlated with the other basins.  相似文献   

14.
《Geobios》2018,51(6):491-506
We present palynological results from the northern sector of the Pulo do Lobo Domain, combining sections studied in Portugal and Spain. A total of 139 samples were studied, of which 56 are positive for palynology. The first age determination for the Pulo do Lobo Formation was achieved, indicating a mid-Frasnian age (Verrucosisporites bulliferus and Pustulatisporites rugulatus). The sediments of Peramora Mélange (Spain) yielded the same palyno-assemblage as that of the Pulo do Lobo Fm. and are interpreted as a part of this formation. The Ribeira de Limas Fm. also yielded mid-Frasnian miospore assemblages, indicating the same age as the Pulo do Lobo Fm. The Santa Iria and Horta da Torre formations present spore assemblages assigned to the late Famennian in both Portugal and Spain. The phyllites interbedded with the quartzites of the Alájar Mélange yielded a palyno-assemblage late Famennian in age that can be correlated to the Horta da Torre Fm. Therefore, the Alájar quartzites are interpreted as a lateral equivalent of the Horta da Torre Fm. in Spain. The palynological results obtained for the units of the northern sector of the Pulo do Lobo Domain are highly consistent and in agreement with stratigraphic mapping and structural interpretations. A detailed discussion of the palynological versus geochronological ages based on detrital zircons is included in this study. The palynological results and their comparison with the worldwide Upper Devonian palynological record suggest a close affinity with NW European palynofloras, placing the Pulo do Lobo Domain within the Avalonian paleobiogeographical province.  相似文献   

15.
The present paper emphasizes the applicability of palynological data as an aid to the solution of the problems related to the correlation of non-ammonitiferous Liassic strata in the Southern Alps with the ammonoid-based standard stages as recognized in the outer-Alpine part of Europe.In the Noriglio Grey Limestone Formation of the Vicentinian Alps, northeastern Italy, rich and well-preserved Liassic palynological assemblages can be abundantly found in the marly intercalations of its upper part; in the lower part palynological assemblages have appeared to be very rare. A qualitative and quantitative analysis of the assemblages has indicated the presence of a single palynological assemblage zone. Minor compositional differences do not warrant a zonal subdivision.The overall composition of the assemblages is characterized by the general dominance of Circulina and smooth trilete spores in combination with a large amount of relatively rarely occurring forms of spores, pollen grains and other acid-resistant microfossils.Because of the presence of rich and well-preserved material, it has been possible to detect a relatively wide range of variability within species of Tigrisporites, Foveosporites, Porcellispora and Crassosphaera.Among the forms which could not be matched with previously described taxa the new formgenus Skarbysporites is formally erected together with the new species Skarbysporites elsendoornii, Skarbysporites puntii, Foveosporites visscheri and Tigrisporites jonkeri. Moreover, an emended diagnosis of Circulina is proposed, implicating the assignment to this formgenus of most forms generally included in Classo pollis. Also the generic diagnosis of Tigrisporites is emended.An evaluation of the Liassic palynological assemblages from the outer-Alpine part of Europe with special reference to their potential in characterizing the ammonoid-based chronostratigraphical subdivisions may indicate that two temporal subdivisions of the Liassic Series on the basis of palynological characteristics are now slowly becoming discernable: an assemblage zone characterizing the Hettangian, Sinemurian and Lower Pliensbachian, and an assemblage zone characterizing the Upper Pliensbachian and Toarcian.Because of the possibility of a correlation with the latter zone, the assemblages from the Noriglio Grey Limestone Formation can be reasonably regarded to be indicative of a Late Pliensbachian—Toarchian age of the source-strata.When considering the ammonoid evidence from the overlying “Cape San Vigilio Oolite” it may be concluded that the upper part of the lower subdivision of the Noriglio Grey Limestone Formation and the Rotzo Member represent the Upper Pliensbachian—Lower Toarcian.Because of its potential in correlating non-ammonitiferous strata from the Southern Alps with the successions in northwestern Europe, it is believed that palynology may earn a prominent place in regional Liassic chronostratigraphy.  相似文献   

16.
Species richness patterns along altitudinal gradients are well-documented ecological phenomena, yet very little data are available on how environmental filtering processes influence the composition and traits of butterfly assemblages at high altitudes. We have studied the diversity patterns of butterfly species at 34 sites along an altitudinal gradient ranging from 600 to 2,000 m a.s.l. in the National Park Berchtesgaden (Germany) and analysed traits of butterfly assemblages associated with dispersal capacity, reproductive strategies and developmental time from lowlands to highlands, including phylogenetic analyses. We found a linear decline in butterfly species richness along the altitudinal gradient, but the phylogenetic relatedness of the butterfly assemblages did not increase with altitude. Compared to butterfly assemblages at lower altitudes, those at higher altitudes were composed of species with larger wings (on average 9 %) which laid an average of 68 % more eggs. In contrast, egg maturation time in butterfly assemblages decreased by about 22 % along the altitudinal gradient. Further, butterfly assemblages at higher altitudes were increasingly dominated by less widespread species. Based on our abundance data, but not on data in the literature, population density increased with altitude, suggesting a reversed density–distribution relationship, with higher population densities of habitat specialists in harsh environments. In conclusion, our data provide evidence for significant shifts in the composition of butterfly assemblages and for the dominance of different traits along the altitudinal gradient. In our study, these changes were mainly driven by environmental factors, whereas phylogenetic filtering played a minor role along the studied altitudinal range.  相似文献   

17.
塔里木盆地北缘侏罗纪孢粉组合   总被引:11,自引:6,他引:11  
本文系统地研究了塔里木盆地北缘侏罗纪的孢子花粉。共发现孢粉化石52属90种,以及藻类化石2属2种。建立侏罗纪的孢粉组合序列如下:(1)Disacciatrileti-Cyathidites组合(早侏罗世早期阿合组),(2)Cyathidites-Cibotiumspora-Disacciatrileti组合(早侏罗世晚期阳霞组),(3)Cyathidites-Neoraistrickia-Disacciatrileti组合(中侏罗世早期克孜勒努尔组),(4)Cyathidites-Clasopolis组合(中侏罗世晚期恰克马克组)。根据孢粉组合特征讨论了地质时代,同时探讨了古植被和古气候的意义。  相似文献   

18.
甲查拉组位于藏南特提斯喜马拉雅北带的江孜盆地,是江孜地区的最高海相地层,被视为新特提斯洋关闭时代的主要证据。通过对甲查拉组剖面的孢粉分析,自下而上划分为3个孢粉组合带:1 Ulmipollenites minor+Ulmoideipites-Myricipites组合带;2 Quercoidites-Caryapollenites组合带;3 Abiespollenites-Betulaceoipollenites+Betulaepollenites组合带。甲查拉组孢粉植物群揭示出其沉积自晚古新世开始,其沉积结束可能延续到早渐新世。推测晚古新世—早始新世为温暖湿润的暖温带或亚热带气候,始新世中晚期为温暖、潮湿的亚热带气候,早渐新世为温和湿润的暖温带气候。  相似文献   

19.
Craneflies (Diptera Tipuloidea) are a typical but poorly known insect group in various moist environments, such as mires. The area of natural mires has strongly decreased in Finland, and there is an urgent need to study and describe the fauna of mires and to determine whether different mire categories support different assemblages of craneflies that might have indicator value. Craneflies were studied using Malaise traps in the Kauhaneva mire system in minerotrophic and ombrotrophic sites, the former subdivided into meso- and oligotrophic sites. A total of 29 cranefly species were recorded. Species richness was highest in mesotrophic sites while the number of species was equally low in oligo- and ombrotrophic sites. Phylidorea squalens, Erioptera flavata, Pedicia rivosa and Tricyphona immaculata were identified as indicators for mesotrophic sites, but no indicators were found for oligo- or ombrotrophic sites. No differences between the species composition of minerotrophic (meso- and oligotrophic combined) and ombrotrophic sites were detected, but when three classes of trophic status were compared, a statistical difference was found. Cranefly species richness in Kauhaneva was low compared to pristine spring habitats. Our results imply, that a focus towards conservation and restoration of mire types with high trophic status would benefit also the conservation of cranefly diversity in the boreal ecoregion. Bioassesments and ecological surveys of craneflies should be designed to cover adequately all trophic status classes within a mire, and especially the mire types with highest trophic status. We also review the distribution and ecology of some potentially regionally threatened cranefly species.  相似文献   

20.
Human impact on an island ecosystem: pollen data from Sandoy, Faroe Islands   总被引:1,自引:0,他引:1  
Aim To investigate the form and dynamics of ecosystems on an isolated island in the North Atlantic before human settlement in the first millennium ad , and the effects of human activities thereafter. Location The island of Sandoy, Faroes (61°50′ N, 6°45′ W). Methods Two sequences of lake sediments and one of peat were studied using pollen analysis and sedimentological techniques. Age models were constructed on the basis of radiocarbon dating and, in one case, tephrochronology. The data were analysed statistically and compared with existing data from the region. Results The pollen data indicate that early Holocene vegetation consisted of fell‐field communities probably growing on raw, skeletal soils. These communities gave way to grass‐ and sedge‐dominated communities, which in turn were largely replaced by dwarf shrub‐dominated blanket mire communities well before the first arrival of humans. There is evidence for episodic soil erosion, particularly in the uplands. Changes in the records attributable to human impact are minor in comparison with many other situations in the North Atlantic margins, and with certain published sequences from elsewhere in the Faroes. They include: (1) the appearance of cereal pollen and charcoal, (2) an expansion of ruderal taxa, (3) a decline in certain taxa, notably Juniperus communis and Filipendula ulmaria, and (4) a renewed increase in rates of upland soil erosion. The reliability of palaeoecological inferences drawn from these sites, and more generally from sites in similar unforested situations, is discussed. Main conclusions The subdued amplitude of palynological and sedimentological responses to settlement at these sites can be explained partly in terms of their location and partly in terms of the sensitivity of different parts of the ecosystem to human activities. This study is important in establishing that the imposition of people on the pristine environment of Sandoy, while far from negligible, especially in the immediate vicinity of early farms and at high altitudes, had relatively little ecological impact in many parts of the landscape.  相似文献   

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