The Floristic Characteristics and Geographical Distribution of the Rosaceae in Xizang

The Rosaceae is one of the five largest families of Xizang flora, consisting of 30 genera with 242 species, the total number of species is slightly less than those of Compositae, Graminae, Leguminosae and Ericaceae in Xizang, amounting to 62.5% of the total number of genera and 28% of the total number of species of the rosaceous flora in China. The four subfamilies of Rosaceae including primitive, intermediate and advanced groups have been found in Xizang. These groups consist of 11 types of floristic elements, i.e. 4 genera belong to cosmopolitan, 9 genera belong to North Temperate, 3, E. Asian-N. American, 3 Sino-Himalayan, 3 Sino-Japanesa, 2 Old World Temperate, 1 Temperate Asian, 2 Mediterranean-W. and O. Asian, 1 C. Asian, I Tropical Asian and 1 endemic to China. It is obvious that Rosaceae in Xizang comprises holarctic, Ancient Mediterranean and paleotropical elements, among which the temperate components are the most dominant. The characteristics of the floristic composition of Rosaceae in Xizang may be summarized as follows: (1) Xizang abounds in both genera and species of the family which are diverse in forms, including the primitive, intermediate and advanced groups, (2) The geographical elements are rather complex, mostly belonging to the temperate, among which the Sino- Himalayan components and the elements endemic to China are dominant, (3) The proportion of plants endemic to China and distributed in Xizang is much higher than those endemic to Xizang itself, but there exist newly arisen species and infraspecific forms or varieties which show that the speciation is apparently still active in Xizang. The rosaceous flora of Xizang is a combination of old and new floristic elements, based on the old floristic components, affected by the upheaval of the Himalayas, the differentiation and speciation have been taking place in the long history. The geographical distribution of Rosaceae in Xizang may be divided into 5 regions, i.e. the northeastern, southeastern, southern, northwestern and northern. The rosaceous plants are most abundant in the southeastern area, next in southern area, fewer in the northeastern and very rare in the northwestern and northern regions. The general tendency of the distribution of Rosaceae in Xizang is that the number of species gradually decreases from the southeast to the northwest and the habit gradually changes from trees, shrubs and herbaceous plants in the southeast to cushion-like scrubs and dwarf perennial herbs in the northwest. These facts clearly show that the uplift of the Himalayas has deeply affected the phytogeographical distribution of Xizang Rosaceae. The rosaceous flora of Xizang has close relationships with those of the adjoring regions, i.e. Yunnan and Sichuan. Besides, it is connected with floras of Nepal, Sikkim, Bhutan nothern Buram and nothern India, but silghtly influenced by the Ancient Mediterranean flora.     

中国苔藓植物的地理分区及分布类型

在对中国苔藓植物相关研究资料进行总结归纳的基础上,对中国苔藓植物的分区进行了重新划分,将最初的7个分区划分为10个分区,从华中区中分出华东区,由华北区中分出华西区,并将青藏区及云贵区内的云南西北部、四川西南部和西藏东南部组成单独的横断山区。就中国苔藓植物的分布类型及可能的分布路线也作了讨论,指出中国苔藓植物的分布路线有3条,一条是从喜马拉雅地区经滇西北、川西沿长江流域到中国的东南部;一条位于喜马拉雅、横断山区和台湾之间;第三条则从喜马拉雅地区通过秦岭直至长白山区。     

The formation and differentiation of the Leguminosae flora in Xizang (Tibet)

Xizang (Tibet) is rich in Leguminosae flora, comprising 41 genera and 254 species so far known, exclusive of the commonly cultivated taxa (including 11 genera and 16 species). There are 4 endemic genera (with 8 species), 10 temperate genera (with 175 species) and 19 tropical genera (with 46 species) as well as the representatives of those genera whose distribution centers are in East Asia-North America, Mediterranean and Central Asia. 1. There are altogether 4 endemic genera of Leguminosae in this region. According to their morphological characters, systematic position and geographical distribution, it would appear that Salweenia and Piptanthus are Tertiary paleo-endemics, while Straceya and Cochlianths are neo-endemics. Salweenia and Piptanthus may be some of more primitive members in the subfamily Papilionasae and their allies are largely distributed in the southern Hemisphere. The other two genera might have been derived from the northern temperate genus Hedysarum and the East Asian-North American genus Apios respectively, because of their morphological resemblance. They probably came into existanc during the uplifting of the Himalayas. 2. An analysis of temperate genera There are twelve temperate genera of Leguminosae in the region, of which the more important elements in composition of flora, is Astragalus, Oxytropis and Caragana. Astragalus is a cosmopolitan genus comprising 2000 species, with its center distribution in Central Asia. 250 species, are from China so far known, in alpine zone of Southwest and Northwest, with 70 species extending farther to the Himalayas and Xizang Plateau. Among them, there are 7 species (10%) common to Central Asia, 12 species (15.7%) to Southwest China and 40 species (60%) are endemic, it indicates that the differentiation of the species of the genus in the region is very active, especially in the subgenus Pogonophace with beards in stigma. 27 species amounting to 78.5% of the total species of the subgenus, are distributed in this region. The species in the region mainly occur in alpine zone between altitude of 3500—300 m. above sea-level. They have developed into a member of representative of arid and cold alpine regions. The endemic species of Astragalus in Xizang might be formed by specialization of the alien and native elements. It will be proved by a series of horizontal and vertical vicarism of endemic species. For example, Astragalus bomiensis and A. englerianus are horizontal and vertical vicarism species, the former being distributed in southeast part of Xizang and the latter in Yunnan; also A. arnoldii and A. chomutovii, the former being an endemic on Xizang Plateau and latter in Central Asia. The genus Oxytropis comprises 300 species which are mainly distributed in the north temperate zone. About 100 species are from China so far known, with 40 species extending to Himalayas and Xizang Plateau. The distribution, formation and differentiation of the genus in this region are resembled to Astragalus. These two genera are usually growing together, composing the main accompanying elements of alpine meadow and steppe. Caragana is an endemic genus in Eurasian temperate zone and one of constructive elements of alpine bush-wood. About 100 species are from China, with 16 species in Xizang. According to the elements of composition, 4 species are common to Inner Mongolia and Kausu, 4 species to Southwest of China, the others are endemic. This not only indicates that the species of Caragana in Xizang is closely related to those species of above mentioned regions, but the differentiation of the genus in the region is obviously effected by the uplifting of Himalayas, thus leading to the formations of endemic species reaching up to 50%. 3. An Analysis of Tropical Genera There are 19 tropical genera in the region. They concentrate in southeast of Xizang and southern flank of the Himalayas. All of them but Indigofera and Desmodium are represented by a few species, especially the endemic species. Thus, it can be seen that they are less differentiated than the temperate genera. However, the genus Desmodium which extends from tropical southeast and northeast Asia to Mexio is more active in differentiation than the other genera. According to OhaShi_,s system about the genus in 1973, the species of Desmodium distributed in Sino-Himalaya region mostly belong to the subgenus Dollinera and subgenus Podocarpium. The subgenus Dollinera concentrates in both Sino-Himalaya region and Indo-China with 14 species, of which 7 species are endemic in Sino-Himalaya. They are closely related to species of Indo-China, southern Yunnan and Assam and shows tha tthey have close connections in origin and that the former might be derived from the latter. Another subgenus extending from subtropical to temperate zone is Podocarpium. Five out of the total eight species belonging to the subgenus are distributed in Sino-Himalaya and three of them are endemic. An investigation on interspecific evolutionary relationship and geographic distribution of the subgenus shows that the primary center of differentiation of Podocarpium is in the Sino-Himalaya region. Finally, our survey shows that owing to the uplifting of the Himalayas which has brought about complicated geographic and climatic situations, the favorable conditions have been provided not only for the formation of the species but also for the genus in cer-tain degree.     

中国热带生物地理北界的建议

以前多个关于中国热带北界的建议由于依据的指标和学科不同,存在很大的差异。我们基于202个中国地理区的植物区系和气象资料,对中国种子植物属的地理成分分布格局及其与气候、经纬度分布的关系进行研究,同时依据覆盖中国北纬30°以南地区的135个地方植物区系资料,对种子植物属的地理成分分布格局进行了研究。结果显示,在中国植物区系中,依据种子植物区系科和属的地理成分(即分布区类型),发现热带分布属中80%以上的区域基本上在中国南部和东南部北纬22°30'以南。在这条界线以南地区,位于基带(低海拔或水平地带性区域)的原始植被为热带森林(热带雨林、季雨林),并且具有在中国分布的典型热带植物科,但在中国西南部,热带森林沿云南西部可达到北纬24°30',在西藏南部的深切河谷可达到北纬29°。这条界线与中国的热带雨林、季雨林区划的北界相符合,亦与植物区系分区上的泛北极植物区系与古热带植物区系的地理分界线相吻合。结合中国植被和植物区系区划,我们建议将北纬22°30'作为中国南部和东南部的生物地理热带北界。这条热带北界比气候上的热带北界(21°30'N,年积温8000℃以上)更北,这暗示中国热带地区在历史上可能曾达到更北的范围,支持在古生态学研究上提出的全新世中期中国东部地区热带和亚热带常绿阔叶林曾北移的结论。     

Floristic analysis of vascular plant genera of North America north of Mexico: characteristics of phytogeography

The phytogeographical characteristics of North America north of Mexico (NANM) were examined based on an analysis of the 1904 indigenous genera of the vascular plants known to the area. According to the worldwide distribution patterns of the genera, the 1904 genera were grouped into ten phytogeographical elements (categories). About 67.3% of the genera found in the native flora of NANM also occur in other areas of the world; of these, 71.4% occur in the Old World. About 32.7% of the 1904 genera are endemic to North America. The origins of the floristic relationships between North America and the rest of the world and the origin of the present-day flora of North America are discussed. The current floristic patterns of the NANM vascular plant genera resulted in part from palaeogeological events such as the unification of tectonic plates into a single supercontinent, Pangaea, and then the breakup of the united supercontinent into Laurasia and Gondwana followed by the fragmentation of Laurasia and Gondwana into individual continents as they are today due to the movement of plate tectonics. Many of the endemic genera of North America likely originated in the North American continent during the Tertiary, particularly during the uplifting of Rocky Mountains.     

西藏壳斗科的地理分布

在野外考察、分类清理和修订的基础上讨论了西藏壳斗科的地理分布。自然分布的西藏壳斗科植物,共３属３３种,集中分布于藏东南的河谷地带和喜马拉雅山脉的聂拉木县,印度栲、刺栲、喜马拉雅石栎和西藏石栎是这些地区海拔２００米以下群落建群种;通麦栎、俅江栎和薄片青冈是西藏海拔１８００－２５００米地段森林植物被的建群种;硬叶高山栎类则是海拔２５００米以上硬叶常绿阔叶林及高山灌丛植被的建群种。种的区系成分分析表明：     

A biogeographical study on tropical flora of southern China

The tropical climate in China exists in southeastern Xizang (Tibet), southwestern to southeastern Yunnan, southwestern Guangxi, southern Guangdon, southern Taiwan, and Hainan, and these southern Chinese areas contain tropical floras. I checked and synonymized native seed plants from these tropical areas in China and recognized 12,844 species of seed plants included in 2,181 genera and 227 families. In the tropical flora of southern China, the families are mainly distributed in tropical areas and extend into temperate zones and contribute to the majority of the taxa present. The genera with tropical distributions also make up the most of the total flora. In terms of geographical elements, the genera with tropical Asian distribution constitute the highest proportion, which implies tropical Asian or Indo‐Malaysia affinity. Floristic composition and geographical elements are conspicuous from region to region due to different geological history and ecological environments, although floristic similarities from these regions are more than 90% and 64% at the family and generic levels, respectively, but lower than 50% at specific level. These differences in the regional floras could be influenced by historical events associated with the uplift of the Himalayas, such as the southeastward extrusion of the Indochina geoblock, clockwise rotation and southeastward movement of Lanping–Simao geoblock, and southeastward movement of Hainan Island. The similarity coefficients between the flora of southern China and those of Indochina countries are more than 96% and 80% at family and generic levels, indicating their close floristic affinity and inclusion in the same biogeographically floristic unit.     

Relationships Between the Bryoflora of Mt. Wuyi,SE China,and Those of Neighbouring Mountain Regions

Mt. Wuyi, located at 27°37‛-27°54‛ N, 117°27‛-117°51‛ E, is the highest mountain in South-East China. Its main peak, Huanggangshan, is 2158 m above the sea level. In 1955, P. C. Chen organized the first expedition to Mt. Wuyi, and the authors investigated the different ravines and the forests of that area in 1976 and from 1979 to 1984 respectively. Up to now 355 species of the bryophytes have been found in Mt. Wuyi. I. The influence of the factors of geological history on the bryoflora of Mt. Wuyi Fujian Province, belonging to Cathaysian, one of three Chinese ancient lands, was a part of ocean until the end of the lower Tertiary. In the early Devonian, Fujian uplifted above the sea level, but it submerged in the sea later, and then uplifted above the sea level again in the upper Triassic. By the end of the lower Triassic the Himalayan movement influenced the paleogeography of China deeply, and the eastern and central mountains of Fujian uplifted again. In the Tertiary, Fujian was influenced by the hot maritime weather, so the tropical evergreen forests existed in southern Fujian at that time. The conclusion was made by Z. B. Zhao in 1983 after his long period of study on geological history of Fujian Province since the Yanshan movement. According to the morden geographical distribution of Chinese bryophytes, it seems that the above influence might be related to the bryophytes of Mt. Wuyi and also the southern part of Zhejian Province. By the end of the Tertiary the weather became cold in most parts of China. Since then the cold weather and hot weather alternated several times. One kind of the endemic elements of the bryoflora formed in the area from the south-eastern coast of China to the southeastern Xizang (Tibet), including Japan. They are not specialized at the family level or closely related to each other, but they have similar distribution and belong to different families. In the Quaternary, Mt. Wuyi gradually uplifted following the Himalayan movement. As the weather cooled down in the upper part of the mountain, deciduous broad-leaved and needleleaved trees increased there. Meanwhile, temperate genera and species of the bryophytes spread and invaded South China and entered Mr. Wuyi. Rhytidiadelphus and Hvlocomium probably began to grow in Mt. Wuyi at that time, and their distribution is quite different from their primary one. On the other hand, a part of tropical and subtropical bryophytes might enjoy the changed weather and environment in the Quaternary and existed in a few small localities of Mt. Wuyi, and the genera Haplomitrium, Endotrichella and Floribundaria are probably their representatives. From the point of view of geological history we are now living in the interglacial period and the present natural conditions will last continuously, so they will steadily influence the bryoflora of Mt. Wuyi in a long period of time. 2. Essential characteristics of the bryoflora in Mt. Wuyi Due to the geographical position and the other factors of Mt. Wuyi the bryoflora is represented by numerous tropical and subtropical elements (34.1%), but the East-Asiatic endemic ones (79.2%) are characteristic of the bryoflora in Mt. Wuyi (Tab. 1). The tropical and subtropical families of the bryophytes, found south of Changjiang (Yangtzi) River, are Haplomitriaceae (1 genus, 3 species), Porellaceae (2 genera, 8 species), Frullaniaceae (2 genera, 10 species), Lejeun eaceae (21 genera, 35 species), Trachypodaceae (3 genera, 4 species), Meteoriaceae (10 genera, 17 species), Neckeraceae (5 genera, 8 species) and Hookeriaceae (3 genera, 3 species). The above 8 families, including 46 genera and 85 species, represent about 1/4 genera (24.3%) and less than 1/4 species (23.9%) of the bryoflora of Mt. Wuyi. Most species of East-Asiatic elements show very close relationships with Japan, and are widely distributed from the low altitude of Mt. Wuyi to the summit of Mt. Huanggangshan. However, the Holarctic species (26.8%) are also important elements of the bryoflora in Mt. Wuyi, showing its transition nature, although it is located in the subtropics. Moreover, the in fluence of the Himalayas also exists in Mt. Wuyi, and the Himalayan elements cover 14.4% in the bryoflora of Mt. Wuyi. The similarity coefficients between the bryofloras of Central and South America, Africa and Oceania and that of Mt. Wuyi are from 5.0-9.2% respectively. The endemic species are not very many and cosmopolitan species are only 7 there. In 1958, P. C. Chen designated Mt. Wuyi as “the transition region of South and North China rich in East-Asiatic genera and species”. His very important conclusion is essentially in accordance with the fact of the bryoflora on Mt. Wuyi. Recently, some of the new records fur ther show the characteristics of the bryoflora in Wuyi. Two facts are worth being mentioned. One is that East-Asiatic genera are only five in Mt. Wuyi. However, there are 9 East-Asiatic genera in Mt. Huangshan more than in Mt. Wuyi; 4 East-Asiatic genera are recorded in Mt. Shennongjia. The other is that epiphyllous liverworts in Mt. Wuyi, consisting of 7 families, 21 genera and 36 species, are less than on Hainan Island and Xishuangbannan, located in the tro pics in China. 3. Comparison between the bryoflora of Mt. Wuyi and those of the neighbouring regions As China covers a very large area, bryofloristic elements are quite different in the diffe rent regions. In this section, we are concentrated on making a comparison between the bryof loras of Mt. Wuyi and the regions belonging to the Central China of the bryoflora named by P. C. Chen. Huaping Forest Region, Guangxi Zhuang Autonomous Region in South China, with both latitute and altitude very similar to Mt. Wuyi, is included in this comparison (Fig. 1). According to the rough estimation, the similarity coefficient of moss genera between Mt. Wuyi and Huaping is 56.3%, and those between the mountain and southern Zhejian and Mt. Huangshan, Anhui, are 62.7% and 51.6% respectively, while the similarity coefficient of the genera of the mossfloras between Mt. Shennongjia and Mt. Wuyi is 46.8%. Table 2 shows the statistics of mosses in Mt. Wuyi and the others, but the bryoflora of Huaping needs further study However, it is very interesting to note that Haplomitrium and Pleurozia of liverworts are both found in Mt. Wuyi and Huaping Forest Region, and the similarity coefficient between the mossfloras of Mt. Wuyi and Zhejian Province is also higher than those mentioned above. Tropical and subtropical elements reduce towards the north in China, and temperate ones increase. Huaping is located in the south, and, as expected, some tropical and subtropical genera such as Hookeriopsis and Symphyodon have been found there, but not in Mt. Wuyi; several temperate genera, such as Schwetschkeopsis and Fauriella, have been recorded in Mt. Huangshan, but not in Mt. Wuyi. For some unknown reasons, Octoblepharum and Neckeropsis are only found in southern Zhejiang, but not in Mt. Wuyi. Mt. Shennongjia, with its main peak over 1000 m higher than that of Mt. Wuyi, is located in its northwest, and more than ten temperate genera, such as, Ceratodon, Aulacomnium Myurella, Bryonoguchia and Abietinella have been found there. Generally, Mt. Wuyi belongs to the central subtropical region of China, and East-Asiatic endemic genera are the main elements of its bryoflora, but the bryoflora also consists of tropical and subtropical elements with some temperate ones. 4. East-Asiatic endemic genera in the bryoflora of Mt. Wuyi In the bryoflora of Mt. Wuyi, one of the main elements, East-Asiatic endemic genera, should not be neglected (Tab. 4). East-Asiatic endemic genera in Mt. Wuyi (five) are less than in Mt. Huangshan and Mt. West Tianmu, although the positions of the latter two are very close to Mt. Wuyi. East-Asiatic endemic genera of liverworts are Trichocolea and Macvicaria so far found in Mt. Wuyi, and the mosses are Myuriopsis, Meteoriella, Pseudospiridentopsis (Fig. 1). Myuriopsis is only distributed in Taiwan Province and Mt. Wuyi, and the other four are distributed in Mt. Huangshan or Mt. West Tianmu, and also in Taiwan, besides in Mt. Wuyi. About thirty EastAsiatic endemic genera have so far been known in China, which means that about one sixth of East- Asiatic endemic genera of the bryophytes occur in Mt. Wuyi. We may notice that nine and seven East-Asiatic endemic genera of the bryophytes have been recorded in Mt. Huangshan and Mt. West Tianmu respectively. In Mt. Shennongjia, Central China, there are four East Asiatic endemic genera, but only two have been found in the Huaping Forest Region, South China. In Mt. Dinghua, located south of Mt. Wuyi, on East-Asiatic endemic genus of the bryophytes has so far been found. East-Asiatic endemic genera of the bryophytes are mainly limited to China, Korea and Japan, including the East Himalayas, rarely occur in South Asia, Siberia of the Soviet Union. Therefore, these genera enjoy a warm and moist environment. In Mt. Wuyi, all the East-Asiatic endemic genera are monotypic ones with a disjunct distribution. Now in Taiwan Province five of six recorded East-Asiatic endemic genera are common to Mt. Wuyi. In Japan, about eleven, i.e. one third of, East Asiatic endemic genera so far found are common to China, which shows a long history of the phytogeographical relationships between Japan and China. East Asiatic endemic genera of the bryophytes might therefore exist on islands of Taiwan Province and Japan before they were separated from the mainland of Asia. However the fossil evidence is still lacking in the bryophytes, so we are not able to discuss about the distribution area and the distribution center of the East-Asiatic bryoflora in detail. The above estimation is more or less related to geological history, and we assume that the East-Asiatic endemic genera have existed at least since the end of the Tertiary. Starting from the Quaternary, the climatic change during glacial epoch has been possibly the most important factor affecting the bryoflora in Asia, and the upheaval of the Himalayas has stimulated the diversity and the specialization of the bryophy tes. Considering these factors, East-Asiatic endemic genera might be the “Tertiary fossil plants”. Another problem is difficult to explain, because Mts. Huangshan, West Tianmu and Shen nongjia were once influenced by glaciation directly, although Chinese geologists hold different views. However, no evidence of glaciation has been found in Mt. Wuyi. It is worth to study the close relationships between Mt. Wuyi, Mt. Huangshan and Mt. West Tianmu, where is the distri bution center of the East-Asiatic endemic genera. The above three mountain regions share half of the East-Asiatic endemic genera, and about 32% genera of the others are found in two of them (Fig. 2). Myuriopsis, one of the East Asiatic types, was only recorded in Taiwan Pro vince, Japan and Korea. Neodolichomitra, occuring in Taiwan Province, is endemic to China. More or less the differentiation has taken place in Mt. Huangshan, Mt. West Tianmu and Mt. Wuyi. The number of the East-Asiatic endemic genera is smaller in Mt. Wuyi, so it is possibly located on the border of the distributional center of the East-Asiatic endemic genera. Moreo ver, three of four East-Asiatic endemic genera in Mt. Shennongjia are also found in Mt. Huang shan and Mt. West Tianmu, but the other East-Asiatic genus in Mt. Wuyi is common to the mountain areas in SW China, the Qinglin Range of NW China, and the isolated mountain areas of NE China. Considering all the characteristics of the bryoflora of Mt. Shennongjia, we assume that Mt. Shennongjia may belong to another distribution center, including SW part of Sichuan Province, and the other neighbouring mountains.     

西藏羽藓科植物的地理分布及区系成分的初步分析

关于西藏苔藓植物的研究,过去报道甚少,据有关资料,W.Mitten(1859)整理鉴定了T.Thomson(1847-1849)在西藏西部及其邻近地区所采标本,发表了66种藓类,其中至今仍隶属于或已调入羽藓科的植物计23种,其后尚有E.S.Salmon(1900),V.F.Brotherus(1948,1929)有过报道。     

Track analysis of the marine palaeofauna from the Turonian (Late Cretaceous)

Aim  To analyse the worldwide distribution patterns of Turonian marine biotas using a panbiogeographical approach.
Location  Turonian localities of southern and north-eastern Brazil, Mexico, Canada, central Europe, England and Morocco.
Method  Panbiogeographical track analysis.
Results  Nine generalized tracks and six nodes were found. The generalized tracks comprise two vicariant track patterns (one northern and one mid-southern) across the Atlantic.
Main conclusions  The generalized tracks show clearly two separate marine biotas, which were associated with the proto-South Atlantic and the proto-North Atlantic oceans. These generalized tracks, as well as the two vicariant track clusters between the north and south Atlantic, are identified by vicariant relationships shared by most of the taxa analysed, and illustrate the final break up of the Gondwana and Laurasia supercontinents and the consequences of vicariant events for the biogeography of the Atlantic Ocean.     

Study on the Floristic Phytogeographical Differentiation of Xizang Tibet

The geoecological conditions of Xizang (Tibet) are very complicated. An approach on the floristic phytogeographical differentiation of Xizang has been made in the present paper with a quantitative floristic method. According to areal types of the species the flora of Xizang may be classified under five major geoelements: the north temperate zone geo-element (N), the Central Asiatic geoelemcnt (C), the Qinghai-Xizang Tibetan Plateau geo-element (T), the Sino-Himalayan geo-element (SH) and the tropical geo-element (Tr). Different diagrams of spectra of floristic elements of Xizang are presented. Four cross-sections were chosen for illustrating the regional differentiation of spectra of floristic elements of Xizang. It is obvious that the SH-geo-element prevails in the Eastern and Southeastern Xizang and the Trgeo-element is confined at lower elevation of the southern flanks of the Himalayas. On the contrary, on the Plateau proper the Tgeoelement dominates and the C-geo-element plays a significant role in the northwestern part of Xizang. It corresponds to the following horizontal zones of vegetation from southeast to northwest: montane forest-alpine meadow-alpine steppe-alpine desert. An example at the southern slopes of the Eastern Himalayas has been taken to investigate the vertical variation of the spectra of floristic elements, the boundary between the both subbelts of the montane evergreen broad-leaved forest belt at an elevation of 1,800 m has been proposed as the upper limit dominated by the tropical geo-element. On the basis of dominance spectra of the fioristic elements in the grid-square system floristic boundaries are defined, which separate different floristic regions from one another, thereafter a floristic division of Xizang has been discussed. There are the sub-region of the "Himalayan flanks belonging to the Indo-Malaysian sub-kingdom of the Palaeotropical kingdom, the Sino-Himalayan sub-kingdom and the Qinghai-Xizang Plateau sub-kingdom of the Holarctic kingdom.     

中国西藏种子植物区系新资料

本文报道了采自西藏喜马拉雅南坡的8个中国种子植物新记录种以及1个西藏新记录属。前者分别是吉隆牛奶菜(Marsdenia roylei)、塔基棕榈(Trachycarpus takil)、喀西蜂斗草(Sonerila khasiana)、旋花锡生藤(Cissampelos convolvulacea)、吉隆角盘兰(Herminium edgeworthii)、尼泊尔西番莲(Passiflora napalensis)、椭穗姜花(Hedychium ellipticum)和藏南象牙参(Roscoea brandisii); 1个西藏新记录属为箭药藤属(Belostemma) (箭药藤 Belostemma hirsutum)。凭证标本存放于中国科学院西双版纳热带植物园标本馆(HITBC)和西藏自治区高原生物研究所标本室(XZ)。     

西藏墨脱县孟加拉虎种群数量调查

孟加拉虎曾在西藏墨脱县各乡镇均有分布记录,但自2002年后该地区未见确认报道。2013—2018年间,我们利用红外相机技术、信息网络收集法和足迹鉴定法调查了墨脱县孟加拉虎的9个潜在分布区域。结果显示,墨脱县仅存1~3只孟加拉虎非定居个体,仅在旱季(每年10月至来年3月)游荡活动于背崩乡、墨脱镇雅鲁藏布江南岸区,以及格当乡金珠藏布南岸区。该区域内孟加拉虎的保护前景不容乐观,其原因是多方面的。本文提出如下建议以加强针对野生孟加拉虎的保护:(1)继续加强虎的基础性监测;(2)加强针对偷盗猎活动的野外巡护与执法管理;(3)加强对原始森林的保护;(4)改善原住民生计,加强宣传教育,以减少对自然资源的消耗;(5)恢复与建立景观廊道,改善栖息地连通性,以促进虎的自然扩散;(6)加强不同机构与参与方之间的合作研究和技术交流。     

Paleobiogeography of Africa: How distinct from Gondwana and Laurasia?

Although Africa was south of the Tethys Sea and originally belonged to the Gondwana, its paleobiogeographical history appears to have been distinct from those of both Gondwana and Laurasia as early as the earliest Cretaceous, perhaps the Late Jurassic. This history has been more complex than the classical one reconstructed in the context of a dual world (Gondwana vs. Laurasia). Geological and paleobiogeographical data show that Africa was isolated from the Mid-Cretaceous (Albian-Aptian) to Early Miocene, i.e., for ca. 75 million years. The isolation of Africa was broken intermittently by discontinuous filter routes that linked it to some other Gondwanan continents (Madagascar, South America, and perhaps India), but mainly to Laurasia. Interchanges with Gondwana were rare and mainly “out-of-Africa” dispersals, whereas interchanges with Laurasia were numerous and bidirectional, although mainly from Laurasia to Africa. Despite these intermittent connections, isolation resulted in remarkable absences, poor diversity, and emergence of endemic taxa in Africa. Mammals suggest that an African faunal province might have appeared by Late Jurassic or earliest Cretaceous times, i.e., before the opening of the South Atlantic. During isolation, Africa was inhabited by vicariant West Gondwanan taxa (i.e., taxa inherited from the former South American-African block) that represent the African autochthonous forms, and by immigrants that entered Africa owing to filter routes. Nearly all, or all immigrants were of Laurasian origin. Trans-Tethyan dispersals between Africa and Laurasia were relatively frequent during the Cretaceous and Paleogene and are documented as early as the earliest Cretaceous or perhaps Late Jurassic, i.e., perhaps by the time of completion of the Tethys between Gondwana and Laurasia. They were permitted by the Mediterranean Tethyan Sill, a discontinuous route that connected Africa to Laurasia and was controlled by sea-level changes. Interchanges first took place between southwestern Europe and Africa, but by the Middle Eocene a second, eastern route — the Iranian route — involved southeastern Europe and southwestern Asia. The Iranian route was apparently the filtering precursor of the definitive connection between Africa and Eurasia. The relationships and successive immigrations of mammal (mostly placental) clades in Africa allow the recognition of five to seven phases of trans-Tethyan dispersals between Africa and Laurasia that range from the Late Cretaceous to the Eocene-Oligocene transition. These Dispersal Phases involve dispersals toward Laurasia and/or toward Africa (immigrations). The immigrations in Africa gave rise to faunal assemblages, the African Faunal Strata (AFSs). All successful and typical African radiations have arisen from these AFSs. We recognize four to six AFSs, each characterized by a faunal association. Even major, old African clades such as Paenungulata or the still controversial Afrotheria, which belong to the oldest known AFS involving placentals, ultimately originated from a Laurasian stem group. Africa was an important center of origin of various placental clades. Their success in Africa is probably related to peculiar African conditions (endemicity, weak competition). Although strongly marked by endemicity, the African placental fauna did not suffer extinctions of major clades when Africa contacted Eurasia. The present geographic configuration began to take shape as early as the Mid-Cretaceous. At that time, the last connections between Africa and other Gondwanan continents began to disappear, whereas Africa was already connected to Eurasia by a comparatively effective route of interchange.     

Phytogeographical relations of the Andean dry valleys of Bolivia

Aim The objective of this study is to examine the phytogeographical affinities of the Andean dry valleys of Bolivia in order to contribute to a better understanding of the Andean dry flora's distribution, origin and diversity. Particular emphasis is given to the analysis of the floristic connections of this flora with more austral parts of South America. Location The dry valleys of Bolivia are located in the Andes of the southern half of the country, at elevations between 1300 and 3200 m. Methods An extensive floristic list compiled by the author to evaluate plant diversity in these Andean regions was used as the base for this study. To accomplish this, all recorded genera and species were assigned, respectively, to 11 and 12 phytogeographical elements established previously by the author. Two phytogeographical spectra were thus obtained and analysed. Results At the genus level, the Andean dry valleys of Bolivia are clearly dominated by genera that have widespread distributions (cosmoplitan and subtropical genera). Many of these reached the Andes from the lowland region of the Chaco. At species level, Andean elements constitute more than 60% of the species total, most of which are restricted to the central‐southern Andes. This suggests that Chaco‐related and Andean genera had considerable levels of speciation in these valleys. Many genera and more than half the species have their northernmost distribution in the dry valleys of Bolivia, thereby underlining strong relationships with central‐southern South America (mainly Argentina, Paraguay and southern Brazil). The data supports the belief of the existence, in central‐southern Peru, of a floristic disjunction in dry to arid environments that separates a tropical dry flora north of this limit from a dry subtropical/warm temperate flora south of it. Main conclusions The Andean dry valleys of Bolivia are diverse plant communities with high levels of endemism (c. 18% of the species). The species of this region are more related to those present in central‐southern South America than to the flora of northern South America that ranges southwards to Peru. Many of the species have restricted distributions in the dry Andes of Bolivia and Argentina, and many genera of these dry valleys have their northernmost distribution in Bolivia/southern Peru, too. The data point to high levels of speciation also in the central Andes.     

Bryophyte evolution and geography

The three extant Divisions comprising the bryophytes extend, as fossils, well back into Palaeozoic time. Bryophyte origin is part of the rise of terrestrial, vascularized, plants with sporopollenin-walled spores in the Silurian. Before the end of Carboniferous time, bryophyte lines were widely present. Separation of Gondwana and Laurasia by the Permian Tethys Sea and subsequent widespread desert episodes fragmented an already diversified bryoflora subjecting it to intense selective pressure. The cool, mesic climate of southern Gondwana provided a refugium for austral bryophytes. Warmer and drier climates of the Permo-Triassic Laurentian-Laurasia favoured drought-adapted or niche-specific groups creating marked systematic discontinuities. The Angaran wet, probably cool, temperate region provided refuge for basic stock for much of today's rich holarctic and wet ‘tropical’ bryofloras. Climatic changes, correlated with tectonic events and the rise of angiosperms, opened habitats favourable for a diversity explosion. Despite demonstrated potential for long-distance dispersal, modern distributions are mostly linked with total floras or establishment on islands prior to niche saturation. Remnants of Gondwanan bryoflora persist in high southern latitudes as disjunctions with the possibility that the folded ranges of the African Cape have been an insular fragment at higher latitudes becoming attached shortly after angiosperm diversification. Floras of southern India and east Africa have common features but the Himalayan flora shows evidence that the Gondwanan flora of the Indian plate was lost during the movement through desert and tropical latitudes; neotropical and palaeotropical floras are distinctive. Much of the northern Australian bryoflora is recently Malesian-derived while the southeast shows strong austral influence and commonality with New Zealand. Tropical Pacific island floras are mostly Malesian-derived but with both holarctic and austral elements present as in Hawaii and the Society Islands. Holarctic bryoflora is circum-polar with temperate areas of Euro-American and far eastern elements floristically bound by disjunct and vicariad species. Kroeber Coefficients of Correlation differ as Pacific island floras are compared and Guttman-Lingoes Smallest Space Coordinates indicates floristic subgroups within Polynesia. Although these and other mathematical treatments yield potentially promising results, the methods are yet unrefined and there is some uncertainty whether characteristics of numbers or of organisms are implicit in the summations.     

西藏东南部棘蛙属一新种记述(两栖纲：蛙科)

对产于西藏东南部察隅和墨脱的察隅棘蛙通过形态特征和数值分类作了进一步比较研究,结果认为：产于察隅的察隅棘蛙是一个有效种,而产于墨脱的标本应为一个新种,即墨脱棘蛙Paa medogensis sp.nov.。     

西藏列当科一新记录属--野菰属

列当科野菰属主要分布于南亚和东南亚,在西藏的分布为新记录。     

高黎贡山北段种子植物区系研究

高黎贡山北段种子植物种类十分丰富,共记载野生种子植物172科,778属,2514种及302变种(亚种),是植物多样性最为丰富的地区之一。区系成分分析表明:1)本区种子植物区系的性质具有鲜明的温带性,并深受热带植物区系的影响,区系地理成分复杂、联系广泛;2)现代种子植物区系是在古南大陆热带亚洲植物区系的基础上,由古南大陆成分及古北大陆成分在漫长的地质历史过程中融合发展而来,许多源于印度-马来、北温带(特别是东亚)的成分在此都产生了较为丰富的特有类群,它们共同演变成今天的植物区系外貌;3)种子植物区系具有明显的水平和垂直替代现象,间断现象也较为显著,主要表现为滇西北-滇东南间断分布或在此线西南侧连续分布;4)种子植物区系的特有现象十分丰富,物种分化强烈,新老兼备,而以新生的进化成分为主,由此表明高黎贡山北段在保存古老成分的同时,又分化出许多新生成分,它是一个孕育新特有现象的重要舞台。     

Ecological and biogeographical studies on the tropical rain forest of south Yunnan,SW China with a special reference to its relation with rain forests of tropical Asia

Abstract. Ecological and biogeographic analyses of the tropical rain forest in south Yunnan were made using data from seventeen sample plots and floristic inventories of about 1000 species of seed plants. The rain forest is shown to be a type of true tropical rain forest because it has almost the same profile, physiognomic characteristics, species richness per unit area, numbers of individuals in each tree species and diameter classes of trees as classic lowland tropical rain forests. As the area is at the northern margin of monsoonal tropics, the rain forest differs from equatorial lowland rain forests in having some deciduous trees in the canopy layer, fewer megaphanaerophytes and epiphytes but more species of lianas as well as more species of microphylls. In its floristic composition, about 80% of total families. 94% of total genera and more than 90% of total species are tropical, of which about 38% of genera and 74% of species are tropical Asian. Furthermore, the rain forest has not only almost the same families and genera, but also the same families rank in the top ten both in species richness and in dominance of stems, as lowland forests in southeast Asia. It is indisputable that the flora of the rain forest is part of the tropical Asian flora. However, most of the tropical families and genera have their northern limits in south Yunnan and most have their centre of species diversity in Malesia. More strictly tropical families and genera have relatively lower species richness and importance compared with lowland rain forests in tropical southeast Asia. Thus, the flora also shows characteristics of being at the margin of the tropics. Based mainly on physiognomy and floristic composition the tropical rain forest of Yunnan is classified into two types, i.e. seasonal rain forest and wet seasonal rain forest, the latter is further divided into two subtypes, i.e. mixed rain forest and dipterocarp rain forest. From analysis of geographic elements it is also shown that the tropical rain forest of Yunnan occurs at a geographical nexus with its flora coming mainly from four sources, i.e. Malesia, south Himalayas, Indochina and China.