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1.
高黎贡山自然保护区西坡垂直带蚂蚁群落研究   总被引:22,自引:2,他引:20       下载免费PDF全文
首次研究了高黎贡山自然保护区西坡垂直带蚂蚁群落及共物种多样性。在北段和中北段随海拔升高优势种数目增加,而在南段随海拔升高优势种数目递减。在北段和中北段海随海拔升高优势种所占百分比递减,而在南段随海拔升高优势种所占比例递增。在西坡4个地段均呈现随海拔升高种数目和密度递减的基本规律。北段和中北段随海拔升高优势度指数降低,中南段和南段随海拔升高优势度指数增大。北段随海拔升高多样性指数递增,中北段多样性指数缺乏规律性,中南段和南段随海拔升高多样性指数递减。北段、中北段和中南段均呈现随海拔升高无效度指数递增规律,而南段表现出随海拔升高均匀度指数递减的相反情况。西坡4个地段垂直带上,蚂蚁群落之间的相似系数几乎均在0.00-0.25,处于极不相似水平,只有1个系数超过此范围,我们认为在原始植被状态下,高黎贡山自然保护区西坡蚂蚁群落的基本规律是随着海拔升高。优势种数目递减,优势种所占比 递增,物种数目递减,优势度指数递增,多样性指数递减,均匀度指数递减。山体中部和下部植被的毁坏导致了实际调查中出现的反常情况。  相似文献
2.
Altitudinal zonation of Andean cryptogam communities   总被引:2,自引:0,他引:2  
3.
Altitudinal changes in the vegetation of the Montane Forest Belt of Mt. Elgon, East Africa, were investigated by analysis of aerial photographs and by sample plots along two transects, one on a relatively wet, and the other on a relatively dry aspect.Classifications for both tree and herb/shrub plots show that the forests along the two transects become increasingly similar floristically with altitude. The total number of tree species recorded is greater for the transect on the moister aspect. The mean altitudinal range for tree species increases on both transects with altitude, while that for herb/shrub species remains constant. It is suggested that the upper altitudinal limits of many species are determined principally by temperature-related factors, while the degree to which species extend their ranges downwards is much influenced by competition.Structural heterogeneity is particularly well marked at altitudes corresponding to the bamboo zone on the wetter slopes and, even in the absence of bamboo, tree density here is much reduced. it is suggested that thicket-forming species, including bamboo, have enhanced competitive ability in intermediate altitude montane forests.Previously advanced classificatory schemes for montane forest vegetation in eastern Africa are examined in the light of the findings.Nomenclature follows Agnew (1974) and Dale & Greenway (1961) with minor modifications after Chapman & White (1970), Mabberley (1973) and Pennington & Styles (1975).The work was funded by a grant from the Natural Environment Research Council (U.K.). We are grateful to the Government of Kenya and to the Forest Department, Kenya, for permission to work on Mt. Elgon. Dr. A. D. Q. Agnew and Miss C. Kabuye very kindly identified some of the plant specimens. The illustrations were drawn by Mr. J. Shaw and the manuseript was critically read by Dr. D. Riley.  相似文献
4.
Zonation of forest vegetation and soils of Mount Cameroon, West Africa   总被引:1,自引:0,他引:1  
Mount Cameroon is an active volcano in a wet part of West Africa. The forest vegetation and associated soils on its southern slopes were studied in 1989, 1991 and 1995 in coupled 0.25 ha plots at altitudes of 180, 600, 1,100, 1,800 and 2,180 m. All lianas and trees >10 cm dbh were enumerated and their structural features quantified. The forests were of large stature throughout. The strangling Schefflera species made a substantial contribution to the very high basal areas at 1,800 m. The associated soils were dominated by andisols derived from volcanic ash that showed a distinct increase with altitude in soil organic matter and total N attributed to lower temperatures. Soil pH, exchangeable K+, Ca2+, Mg2+, effective cation-exchange capacity and percentage base saturation showed very marked increases explained by the influence of recent volcanic ashfalls. Available N and P showed less distinct trends with altitude. Although there is a large decrease in tree species richness with altitude, forest stand growth (as compared on a basal area basis) does not appear to be limited by soil fertility or temperature. The forest line (altitude treeline and extensive gaps below it) appear to be controlled by periodic volcanic activity, ashfalls and lava flows, which can destroy existing forest through soil burial and fire effects and inhibit regrowth on bare lava flows and deep deposits of volcanic ash.  相似文献
5.
Five altitudinal pteridophyte zones are established along the northeastern altitudinal slopes of Mt. Banahaw de Lucban, Quezon, Luzon Is., Philippines using cluster- and ordination analyses, namely: Zone 1, Cyathea contaminans – Dicranopteris–Nephrolepis–Diplazium patches at 700–800 m a.s.l.; Zone 2, Sphaerostephanos hirsutus var. hirsutus – Selaginella delicatula patches at 750–900 m a.s.l.; Zone 3, Cyathea philippinensis – Selaginella patches at 900–1200 m a.s.l.; Zone 4, Cyathea philippinensis – Cyathea callosa–Asplenium cymbifolium–Selaginella cumingiana patches at 1200–1550 m a.s.l. and; Zone 5 which is further divided into Sub-zone 5A, Cyathea callosa – Cyathea loheri-Hymenophyllaceae patches at 1550–1800 m a.s.l. and Sub-zone 5B, Cyathea loheriCephalomanes apiifolia patches at 1800–1875 m a.s.l. These pteridophyte zones coincide with the woody species zones of Mt. Banahaw de Lucban but differ significantly with the altitudinal fern zones of Mt. Makiling. Stepwise multiple regression analysis reveals that altitude exhibits a linear relationship with pteridophyte species distribution. Altitude and soil pH influence 65% of the variation in principal component 1 [PC1 = 0.0839 + 0.0010(altitude) − 0.2072(soil pH); r = 0.8058] and 27% of the variation in principal component 2 [PC2 = 2.0453 − 0.0005(altitude) − 0.2560(soil pH); r = 0.5206]. Thirty-three (33) species are preferential to specific microenvironments along the altitudinal gradient, making them effective altitudinal zone markers and biodiversity conservation indicators for the forest ecosystem of Mt. Banahaw de Lucban.  相似文献
6.
Andreas Hemp 《Plant Ecology》2002,159(2):211-239
140 taxa of 61 genera in 24 families of pteridophytes were recorded on the southern slopes of Mt. Kilimanjaro. These represent about one third of the entire pteridophyte flora of Tanzania. The families richest in species are the Aspleniaceae, the Adiantaceae, the Dryopteridaceae, the Thelypteridaceae and the Hymenophyllaceae. Due to its luxuriant montane rain forest, which receives a precipitation of up to over 3000 mm, Mt. Kilimanjaro is distinctly richer in pteridophyte species than other volcanoes in East Africa. However, compared with the mountains of the Eastern Arc, the number of pteridophytes on Mt. Kilimanjaro is smaller. This can be explained by the widely destroyed submontane (intermediate) forest rather than by the higher age of the Eastern Arc Mts.The altitudinal distribution of all ferns was investigated in 24 transects. On the southern slopes of Mt. Kilimanjaro they were found in an altitudinal range of 3640 m. Cyclosorus quadrangularis, Azolla nilotica, Azolla africana andMarsilea minuta are restricted to the foothills, while Polystichum wilsonii, Cystopteris nivalis and Asplenium adiantum-nigrum are species found in the highest altitudes.Based on unidimensionally constrained clustering and on the analysis of the lowermost and uppermost occurrence of species, floristic discontinuities within the transects were determined. From these data and from an evaluation of the distribution of ecological groups and life forms, 11 altitudinal zones could be distinguished: a colline zone (–900 m asl), a submontane zone (900–1600 m asl) with lower and upper subzones, a montane zone (1600-2800 m asl) divided into 4 subzones, a subalpine zone (2800–3900 m asl) with lower, middle and upper subzones, and finally a (lower) alpine zone above 3900 m. The highest species numbers were observed in the lower montane forest belt between 1600 and 2000 m altitude. The zonation of ferns found at Mt. Kilimanjaro corresponds well with the vegetational zonation described by other authors using bryophytes as indicators in different parts of the humid tropics.  相似文献
7.
Pollen analytical data from a 23-m core taken in the Jammertal subglacial basin, near Biberach an der Riss, has given a continuous sequence from the Rissian late-glacial to the beginning of the Mid-Würmian. The Eemian interglacial is completely preserved and with a high temporal resolution. Two interstadials, Stafflangen I and II, are recognised in the Lower Würmian. These two woodlands were dominant byPinus andPicea and there was a small but significant (up to 12%) component of thermophilous deciduous tree pollen. Stafflangen I and II are correlated with St. Germain I and II as known from Grande Pile. The north-eastern areal boundary of thermophilous deciduous trees lies between Jammertal and Grande Pile. Furthermore, it was possible for the first time to define and describe altitudinal zonation in Eemian vegetation. During the Eemian, the altitudinal boundary of shade-tolerant deciduous trees (Carpinus, Abies andPicea) lay at ca. 625 m in Upper Swabia and the Swiss Alpine foreland, and at ca. 560 m in Upper Bavaria to the east. The sites, which were dominated byCarpinus occur below this limit whereasAbies orPicea show a preference for habitats at higher altitudes.  相似文献
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9.
An altitudinal sampling transect was established in a subtropical mountain river to determine if replacement between two mayfly faunal components (oligostenothermal and polystenothermal) occurred. We detected three main groups: Group A, species with high abundance at higher stations, declining abruptly downstream; Group B, species with maximum abundance at lower elevations; either declining abruptly upstream or absent from higher elevations; and Group C, species with little elevational change. The physical and chemical variables did not change abruptly with altitude during our winter sampling, although the distribution of groups A and B species did. The observed distributional patterns of groups A and B do not appear to be correlated with variations in the physical and chemical variables surveyed.  相似文献
10.
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