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1.
Paleobiotic assemblages from the Deccan infra- and intertrappean beds are reviewed in great detail. Three distinct paleoenvironments (fluvio-lacustrine/terrestrial, brackish water and marine) have been identified within the infra- and intertrappean biotic assemblages of peninsular India. Recently, marine incursions have been recorded in a few of the Deccan intertrappean beds exposed in central and south-eastern India. The intertrappean beds have yielded marine planktic foraminiferans and freshwater/brackish water ostracods. The affinities of the paleobiotas are commonly considered to show a mixed pattern resulting from the addition of Gondwanan and Laurasian elements to endemic Indian taxa. During the last four decades, various biogeographic models (southern and northern connections) have been proposed to explain the presence of anomalous biogeographic biota in the Late Cretaceous of India. Based on the recovered fauna and flora assemblages, the Cretaceous–Paleogene boundary has been marked and a Late Cretaceous to Early Paleocene age has been assigned to these Deccan volcano-sedimentary sequences.  相似文献   

2.
金沙江干热河谷植物区系和生态多样性的初步研究   总被引:9,自引:0,他引:9  
对金沙江干热河谷中植物区系成分和生态多分的多样性进行了初步研究。研究显示,金沙江干热河谷虽然气候干燥,给植物的正常生长带来不利影响,但河谷所具有充沛的光、热因子却为许多热带、亚热带植物的生长提供了条件,而特殊的地理位置和地形也为许多植物物种的保存创造了有利条件,形成一些植物的保留地。其植物区系成分中热带成分占67.26%,高于中国、云南,以及滇中。生长型以草本植物为主,其所占比例超过半数;生活型以  相似文献   

3.
The Kangchenjunga Landscape (KL) in the Eastern Himalayas is a transboundary complex shared by Bhutan, India, and Nepal. It forms a part of the ‘Himalayan Biodiversity Hotspot’ and is one of the biologically richest landscapes in the Eastern Himalayas. In this paper, we use secondary information to review and consolidate the knowledge on the flora of the KL. We reviewed 215 journal articles, analysed the history of publications on the flora of the KL, their publication pattern in terms of temporal and spatial distribution and key research areas. Our review shows that the landscape has a long history of botanical research that dates back to the 1840s and progressed remarkably after the 1980s. Most of the studies have been carried out in India, followed by Nepal and Bhutan. The majority of these have been vegetation surveys, followed by research on ethnobotanical aspects and Non-Timber Forest Products (NTFPs). This paper describes the forest types and characteristic species of the KL and details the species richness, diversity and dominant families of seed plants. A total of 5198 species of seed plants belonging to 1548 genera and 216 families have been recorded from the landscape, including 3860 dicots, 1315 monocots and 23 gymnosperms. Among families, Orchidaceae is the most diversely represented family in terms of species richness. This paper also draws attention to the threatened and endemic flora of the KL, including 44 species that are threatened at national and global level and 182 species that are endemic. Finally, the paper reviews the major challenges facing the KL, the conservation efforts and practices that are currently in place and recommends systematic and comprehensive floral surveys, particularly long-term data collection and monitoring and transboundary collaboration, to address the existing knowledge gaps on floral diversity of the KL.  相似文献   

4.
We studied 24 wetlands along a 296‐km portion of the lower Missouri River floodplain, USA during 1996–1998. Our goal was to examine relationships between wetland characters and freshwater turtle diversity. We collected data on a total of 2201 individual captures of six freshwater turtle species. Ten species variables (richness, evenness, proportion of lentic species combined, proportion of lotic species combined, and proportions of six individual species) described the turtle assemblage structure and were associated with six broad wetland categories (remnant oxbow, remnant slough, connected scour, isolated scour, temporary farmed, and temporary not farmed) as well as with six abiotic (water depth, distance from the river, duration dry, duration flooded, size, and turbidity) and two biotic (primary and secondary productivity) wetland characters. Repeated‐measures MANOVA and ANOVA revealed highest diversity in remnant sloughs and oxbows as well as in newly created scour wetlands and lowest diversity in temporary wetlands. Multiple regressions and correlations indicated that the single most important wetland characteristic for high turtle diversity was a low annual duration of drying. Oxbows supported the highest proportions of lentic turtles; while connected scours supported the highest proportions of lentic turtles. Lentic species proportions were highest in wetlands that were frequently flooded, relatively distant from the Missouri River, and insect rich, while lotic species proportions were highest in wetlands that were turbid, close to the river, and relatively insect poor. The cohabitation patterns of several turtle species suggest that direct or indirect interactions between species may affect assemblage structure. Based on our broad array of wetlands, we identified crucial wetland types and characteristics that were associated with maximum diversity for freshwater turtles. Empirical studies similar to ours across broad landscapes are needed for a variety of wetland floral and faunal groups before sound conservation and management recommendations can be formulated.  相似文献   

5.
Abstract. We studied the vegetation distribution in eight landscape types distinguished along an altitudinal gradient in the Trans‐Himalayan region of Ladakh, India. The point‐intercept method was used for vegetation sampling. Six plant communities were distinguished by cluster analysis. Of these 6 communities, three communities were dominated by shrub species. Table lands are the landscape type with the highest species diversity followed by undulating areas and river beds. Most plant species were restricted to one landscape type.  相似文献   

6.
Numbers of species and genera,endemic genera,extant primitive genera,relationship and distribution patterns of presently living Chenopodiaceae(two subfamilies,12 tribes,and 118 genera)are analyzed and compared for eight distributional areas,namely central Asia,Europe,the Mediterranean region,Africa,North America,South America, Australia and East Asia. The Central Asia,where the number of genera and diversity of taxa are greater than in other areas,appears to be the center of distribution of extant Chenopodiaceae.North America and Australia are two secondary centers of distribution. Eurasia has 11 tribes out of the 12,a total of 70 genera of extant chenopodiaceous plants,and it contains the most primitive genera of every tribe. Archiatriplex of Atripliceae,Hablitzia of Hablitzeae,Corispermum of Corispermeae,Camphorosma of Camphorosmaea,Kalidium of Salicornieae,Polecnemum of Polycnemeae,Alexandra of Suaedeae,and Nanophyton of Salsoleae,are all found in Eurasia,The Beteae is an Eurasian endemic tribe,demonstrating the antiquity of the Chenopodiaceae flora of Eurasia.Hence,Eurasia is likely the place of origin of chenopodiaceous plants. The presence of chenopodiaceous plants is correlated with an arid climate.During the Cretaceous Period,most places of the continent of Eurasia were occupied by the ancient precursor to the Mediterranean,the Tethys Sea.At that time the area of the Tethys Sea had a dry and warm climate.Therefore,primitive Chenopodiaceae were likely present on the beaches of this ancient land.This arid climatic condition resulted in differentiation of the tribes Chenopodieae,Atripliceae,Comphorosmeae,Salicornieae,etc.,the main primitive tribes of the subfamily Cyclolobeae. Then following continental drift and the Laurasian and Gondwanan disintegration, the Chenopodiaceae were brought to every continent to propagate and develop, and experience the vicissitudes of climates, forming the main characteristics and distribution patterns of recent continental floras. The tribes Atripliceae, Chenopodieae, Camphorosmeae, and Salicornieae of recent Chenopodiaceae in Eurasia, North America, South America, southern Africa, and Australia all became strongly differentiated. However, Australia and South America, have no genera of Spirolobeae except for a few maritime Suaeda species. The Salsoleae and Suaedeae have not arrived in Australia and South America, which indicates that the subfamily Spirolobeae developed in Eurasia after Australia separated from the ancient South America-Africa continent, and South America had left Africa. The endemic tribe of North America, the tribe Sarcobateae, has a origin different from the tribes Salsoleae and Suaedeae of the subfamily Spirolobeae. Sarcobateae flowers diverged into unisexuality and absence of bractlets. Clearly they originated in North America after North America had left the Eurasian continent. North America and southern Africa have a few species of Salsola, but none of them have become very much differentiated or developed, so they must have arrived through overland migration across ancient continental connections. India has no southern African Chenopodiaceae floristic components except for a few maritime taxa, which shows that when the Indian subcontinent left Africa in the Triassic period, the Chenopodiaceae had not yet developed in Africa. Therefore, the early Cretaceous Period about 120 million years ago, when the ancient Gondwanan and Laurasian continents disintegrated, could have been the time of origin of Chenopodiaceae plants.The Chinese flora of Chenopodiaceae is a part of Chenopodiaceae flora of central Asia. Cornulaca alaschnica was discovered from Gansu, China, showing that the Chinese Chenopodiaceae flora certainly has contact with the Mediterranean Chenopodiaceae flora. The contact of southeastern China with the Australia Chenopodiaceae flora, however, is very weak.  相似文献   

7.
藜科植物的起源、分化和地理分布   总被引:27,自引:0,他引:27  
全球藜科植物共约130属1500余种,广泛分布于欧亚大陆、南北美洲、非洲和大洋洲的半干旱及盐碱地区。它基本上是一个温带科,对亚热带和寒温带也有一定的适应性。本文分析了该科包含的1l族的系统位置和分布式样,以及各个属的分布区,提出中亚区是现存藜科植物的分布中心,原始的藜科植物在古地中海的东岸即华夏陆台(或中国的西南部)发生,然后向干旱的古地中海沿岸迁移、分化,产生了环胚亚科主要族的原始类群;起源的时间可能在白垩纪初,冈瓦纳古陆和劳亚古陆进一步解体的时期。文章对其迁移途径及现代分布式样形成的原因进行了讨论。  相似文献   

8.
《Palaeoworld》2020,29(1):161-175
Understanding the flora preserved in the Late Cretaceous–Early Paleocene Deccan volcanic associated sediments is significant as it gives insight into the floral composition during Deccan volcanic activity. This time interval is also associated with extinction and evolution of many angiosperm families on the Indian subcontinent. The record of palynomorph bearing intertrappean beds of Shankar Lodhi in Chandrapur district and Shimbala in Yavatmal district of Maharashtra from southeastern part of Deccan volcanic province provides information on biodiversity, age and depositional environment of the Deccan province. These intertrappean beds are characterized by presence of Maastrichtian age marker taxa such as Azolla cretacea, Jiangsupollis and Echitricolpites. Aquatic palynoassemblage such as, Azolla cretacea, Crybelosporites intertrappea, Gabonisporis vigourouxii and Sparganiaceaepollenites are dominant in Shankar Lodhi intertrappean beds. Presence of taxa Crybelosporites, Incrotonipollis and Periporopollenites in the intertrappean beds of the study area and their global geological history suggest their Gondwanan origin.  相似文献   

9.
《Palaeoworld》2022,31(3):485-506
A Late Cretaceous fossil flora composed of five fossil seed genera and two charophyte genera was discovered and reported here from the siltstone and green marl band of the Lameta Formation at the Chui Hill section and the Chhota Simla Hill section in the Jabalpur area. On the basis of comparative studies, including thin-section and XRD analysis, the palaeoenvironment is deduced to be arid to semi-arid fluvial-lacustrine. The recovered flora suggests Laurasian palaeobiogeographic affinity and shows the dispersal route from Europe to India via Africa.  相似文献   

10.
Sedimentary sequences in the Columbia Plateau region of the Pacific Northwest ranging in age from 16–4 Ma contain fallout tuffs whose origins lie in volcanic centers of the Yellowstone hotspot in northwestern Nevada, eastern Oregon and the Snake River Plain in Idaho. Silicic volcanism began in the region contemporaneously with early eruptions of the Columbia River Basalt Group (CRBG), and the abundance of widespread fallout tuffs provides the opportunity to establish a tephrostratigrahic framework for the region. Sedimentary basins with volcaniclastic deposits also contain diverse assemblages of fauna and flora that were preserved during the Mid-Miocene Climatic Optimum, including Sucker Creek, Mascall, Latah, Virgin Valley and Trout Creek. Correlation of ashfall units establish that the lower Bully Creek Formation in eastern Oregon is contemporaneous with the Virgin Valley Formation, the Sucker Creek Formation, Oregon and Idaho, Trout Creek Formation, Oregon, and the Latah Formation in the Clearwater Embayment in Washington and Idaho. In addition, it can be established that the Trout Creek flora are younger than the Mascall and Latah flora. A tentative correlation of a fallout tuff from the Clarkia fossil beds, Idaho, with a pumice bed in the Bully Creek Formation places the remarkably well preserved Clarkia flora assemblage between the Mascall and Trout Creek flora. Large-volume supereruptions that originated between 11.8 and 10.1 Ma from the Bruneau-Jarbidge and Twin Falls volcanic centers of the Yellowstone hotspot in the central Snake River Plain deposited voluminous fallout tuffs in the Ellensberg Formation which forms sedimentary interbeds in the CRBG. These occurrences extend the known distribution of these fallout tuffs 500 km to the northwest of their source in the Snake River Plain. Heretofore, the distal products of these large eruptions had only been recognized to the east of their sources in the High Plains of Nebraska and Kansas.  相似文献   

11.
This study investigates the use of aquatic macrophytes as indicators of stream condition in catchments with varied land use and levels of riparian disturbance in the Wet Tropics region of North Queensland (Australia), a region of global significance in terms of faunal and floral diversity. In a paired catchment design spatial variations in macrophyte assemblage structure were characterised using multivariate and univariate techniques. Seven metrics were trialled: total macrophyte cover, species richness, % alien taxa, % native taxa, % submerged taxa, % emergent taxa and % Poaceae. Forty-four macrophyte taxa were recorded from the study area. Poaceae, Cyperaceae and mosses were the most frequently recorded taxa. Upper catchment areas in all tributaries surveyed were dominated by mosses and Cladopus queenslandicus (Domin) C.D.K. Cook (Podestemaceae). This assemblage occurred in areas with intact riparian canopy cover and good overall riparian condition. Macrophyte assemblages in lower catchment areas were distributed along gradients of riparian disturbance. Simultaneous autoregression model coefficients indicated that riparian condition had a negative influence on macrophyte cover, species richness and the proportions of alien taxa, emergent taxa and Poaceae present at sites in the Wet Tropics. Macrophyte metrics were not strongly influenced by the types of land use or water quality. These findings suggest that a riparian condition assessment would provide an adequate first assessment of the state of aquatic macrophyte assemblages in Wet Tropics streams.  相似文献   

12.
Patterns of zonal changes in the species composition, diversity, and community structure of Orthoptera were studied along the latitudinal series of steppe types from meadow to desert steppe in European Russia. The maximum abundance of Orthoptera was recorded in the typical steppe, while the maximum species richness shifted to the southern dry steppe. Changes in the ecological preferences of orthopterans due to aridization are shown by the example of zonal communities. A gradual decline of the forest-steppe orthopteran complex and an increase in the number of semidesert and desert species are demonstrated. The changes in the species composition are accompanied by the intra-landscape shifts of areas with high species diversity. Most species in the meadow steppe occupy mesophytic habitats in depressions. In the typical and dry steppe, the species richness and abundance are restricted to habitats with zonal and xerophytic vegetation. In the desert steppe, the species diversity is the highest in dry habitats, including halophytic ones, where xerophilic and desert species predominate. The diversity and evenness indices increase in the northern and southern ecotones of the steppe zone.  相似文献   

13.
An Ordovician stratigraphically admixed palynomorph assemblage that contains palynomorphs eroded from Middle through Upper Ordovician strata characterizes the Hawban Member (restricted) of the Sarah Formation in central Saudi Arabia. This distinctive assemblage, combined with detailed sedimentology, helps identify the presence of Hirnantian Gondwanan glacial sediments on the Arabian Plate. Similar Ordovician admixed assemblages have been recognized from Upper Ordovician glacial sediments elsewhere along the Gondwanan margin. Within Saudi Arabia the composition of reworked assemblages depends upon the stratigraphic succession exposed to glacial erosion. Sylvanidium? hawbanense, which is one of the acritarchs found in glacial sediments, is newly described from Arabian Upper Ordovician strata.  相似文献   

14.
Extensive work done in the last decade on the sedimentary beds intercalated with the Deccan volcanic flows (infra‐ and intertrappean) has demonstrated the vast potential of these rocks for vertebrate, invertebrate and plant fossils. The infra‐ and intertrappean beds, especially those exposed on the eastern margin of the Deccan Traps, produced a large number of fossils which made it possible to establish the age and duration of Deccan volcanism (late Cretaceous—early Palaeocene) with some degree of confidence. Affinities of the late Cretaceous infratrappean vertebrates, such as pelomedusid turtles and sauropod dinosaurs, lie with those of Gondwanan landmasses. It seems more likely that these taxa are relicts of the Gondwanan stock that boarded the Indian plate well before its separation from Madagascar 70–80 Ma ago. Remnants of the former Gondwanaland fauna, such as pelomedusid turtles, leptodactylid frogs and titanosaurid dinosaurs did persist in relatively younger (latest Cretaceous) intertrappean beds. In addition to these Gondwanan elements, the intertrappean beds register many North American, European and Central Asiatic taxa (pelobatid and discoglossid frogs, anguid lizards, alligatorid crocodiles, palaeoryctid mammals, ostracodes and charophytes) suggesting that a contact between India and southern Asia was already established by the end of Cretaceous. An early India/Asia collision, long before the widely accepted early to middle Eocene date, is favoured to explain the presence of Laurasian elements in the late Cretaceous of India.  相似文献   

15.
福建永春闽楠天然林植物区系和物种多样性研究   总被引:2,自引:0,他引:2  
通过对福建永春闽楠天然林群落进行系统调查,并对该群落植物区系成分、垂直结构特征和物种多样性进行分析。结果表明,该群落共有维管束植物231种,隶属于87科172属。各层次区系均以泛热带和热带亚洲成分较高。群落垂直结构复杂,物种多样性指数以灌木层最高。  相似文献   

16.
We characterize the vegetation types of the upper basin of the Madeira River in the Brazilan state of Rondônia, a biodiverse region with elevated rates of habitat loss. Vegetation and environmental parameters were recorded from 37 observation points distributed along and near a 160 km stretch of the Madeira River and representing the range of regional environments. Analysis of structure and floristic variables, as well as associated edaphic attributes and water table fluctuation, permitted recognition of five main vegetation types and seven subtypes. Open Ombrophilous Forest was the most frequently encountered vegetation type and occurred on well-drained, nutrient-poor soils, whereas Dense Ombrophilous Forest was seldom recorded. Alluvial Ombrophilous Forests (várzea) were found along a narrow strip of land along the banks of the Madeira River on the most fertile soils in the study area. Semideciduous Forests were found on small areas of rocky outcrops with shallow soils and reduced water availability during the dry season. Campinaranas, which range from open savanna physiognomies to closed canopy forests, were found to be a key environment in the lowlands south of the Madeira River on silty hydromorphic soils, where they harbor a peculiar flora tolerant of flooding during the rainy season. Our classification of the main vegetation types in the upper Madeira River illuminates a high degree of floristic and environmental heterogeneity in a highly threatened region. Our results will be useful for designing conservation strategies aimed at protecting the full range of floristic diversity present in the region.  相似文献   

17.
Monalisa Paul 《农业工程》2021,41(3):204-209
The present study deals with the diversity of moths along with the contrasting six selected landscapes and three seasons in Delhi, India for the years 2015–16 and 2016–17. Among the 51 species of moths recorded, relative abundance of family Noctuidae (61%) was found to be the highest followed by Erebidae (21.6%) and Crambidae (13%). Species diversity was found to be the highest during pre-monsoon season, whereas among the study sites Dwarka not only had the highest relative abundance of moth species (26%) but also the highest biodiversity indexes. Prior to this study in Delhi, only documentation of this faunal group, mostly in the form of occasional observations or reporting or compilation of checklists were done which have their own significance. The findings of this study indicate the significance of the urban green areas in the city to support a wide array of moths.  相似文献   

18.
Agricultural landscapes provide financial livelihoods for farming communities in rural areas. However, such agroenvironments can significantly impact the local floral biodiversity and introduce harmful invasive species to the ecosystem. Despite the prominence of plantations throughout the tropics, their effects on local flora are limited to only a few specific cash crops and geographical regions. Here, we compared the species richness and structural diversity of vegetation in natural forest fragments and three types of vanilla plantation within the Sava region of north-east Madagascar ranging from those within or adjacent to existing forests, to intensively cultivated plantations. We recorded data on plant species abundance, diameter at breast height and canopy cover within multiple sites of each habitat. We used abundance data to calculate species richness indices, and we compared these metrics between habitats. Forested habitats contained a significantly higher floral species richness, structural diversity and more endemic and regionally native species than nonforested, anthropogenic vanilla plantations. However, our results suggest that the high floral species richness and structural diversity of natural forests can be partially achieved in vanilla plantations, depending on the site's management regime; traditionally managed vanilla plantations located close to natural forests can support diverse floral communities. These encouraging findings for plant conservation and sustainable agroforestry in Madagascar suggest that that newly created vanilla plantations and already existing nonforested plantations should endeavour to follow the more traditional forested approach to enhance the future sustainability and promote floristic diversity.  相似文献   

19.
Tropical dry evergreen forests (TDEF) are a unique forest type found along the east coast of India. They mostly occur as small, isolated fragments of varying sizes (0.5 to ≈10 ha) and are considered as endangered forests types in peninsular India. Although plant diversity is well documented in these forests, there is a paucity of ecological studies vital for conservation and for planning restoration activities. We studied reproductive biology of 13 woody species: four trees, six shrubs, and three lianas in fragments of TDEF in southern India. The phenology of reproduction, floral biology, anthesis and sexual system of each species were recorded. The pollination mode was assessed through observations of the visitation frequency of pollinators and from the floral characters. The breeding system was determined by hand-augmented self- and cross-pollination experiments. The plants flowered during the dry season from January to July. Plants of nine species had both flowers and fruits at the same time. Twelve species were hermaphrodites and one was polygamo-dioecious. Flowers of 11 species opened at dawn and two at dusk. Four species were self-incompatible and six were self-compatible. Natural fruit set ranged from 10% to 56%, self-incompatible species having low fruit set. Cross-pollen augmentation increased fruit set, suggesting presence of outcrossing in all species. The majority of plants species (85%) had a generalized pollination system, receiving visits from diverse insects, such as social bees, solitary bees, wasps, moths and flies. However, only few of them were functionally important for the species. Two species namely: Capparis brevispina and C. zeylanica had butterflies and birds, respectively, as their main pollinators. Our data reveal that there is a predominance of outcrossing in plant species and a generalized pollination system in these forests. We suggest that restoration of TDEFs is crucial as habitats, not only for wild plants but also for pollinating insects.  相似文献   

20.
Aim The aim of the study was (1) to describe the biodiversity of the sphingid assemblage in a Cerrado area in the Triângulo Mineiro region, south‐east of Brazil; (2) to evaluate the seasonal variations in species composition; (3) to compare the faunistic relationships between the Cerrado biome and adjacent ecosystems; and (4) to analyse the biogeographical pattern of species distribution in the Neotropical region in a historical context. Location Panga Ecological Station (PES), 30 km south of the city of Uberlândia, and other areas of the Triângulo Mineiro region, Minas Gerais state, south‐eastern Brazil. Methods Moth richness and abundance were monitored monthly at the PES from August 2003 to July 2004, with additional collections at this locality in 2001/2002, 2005 and 2006. Complementary moth richness and abundance data were also collected in other areas of the Triângulo Mineiro region. All collections were made using light traps, and the hawkmoths were mounted and identified. Cluster analysis, rarefaction curves and estimators of total species richness were used to compare the Cerrado hawkmoth assemblage with assemblages derived from other surveys in the Neotropics. Results In total, 61 hawkmoth species were recorded for the study region and their occurrence was markedly seasonal. The hawkmoth assemblage in the study area presented the closest similarity with rain forest areas and with a tropical dry forest area in Central America. The area shared species with both rain forest and seasonally dry tropical forest (SDTF) ecosystems, including supposedly endemic species previously recorded only in the latter areas. Rarefaction curves and estimators of the total number of species showed species richness to be comparable with other highly diverse forest areas in the Neotropics, such as the Brazilian Amazon and Costa Rica. Main conclusions This short‐term study is the first systematic survey of hawkmoths in the Cerrado. It has recorded around 22% of the South American fauna and highlighted the high species richness of the region, which compares favourably with that in other rain forest ecosystems. The survey indicates high regional diversity, and has shown that the Cerrado harbours a hawkmoth fauna comprising both rain forest elements, probably distributed along humid gallery forest corridors, and SDTF elements, supporting the idea of a historical Pleistocene arc connecting the Caatinga domain and other seasonal dry forest areas across the Cerrado region.  相似文献   

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