On the Classification of Forest Vegetation in Xishuangbanna,Southern Yunnnan

Xishuangbanna of southern Yunnan is a region of extremely interest to biologists and also a hotspot for biodiversity conservation . It is located in a transitional zone from tropical Southeast Asia to temperate East Asia biogeographically. The present paper reviewed vegetation types of Xishuangbanna and suggested a revised classification system based on theupdated study results over the last two decades . By combining physiognomic and floristic characteristics with ecological performances and habitats , the primary forest vegetation in Xishuangbanna can be organized into four main vegetation types: tropical rain forest, tropical seasonal moist forest, tropical montane evergreen broad-leaved forest and tropical monsoon forest. The tropical rain forest can be classified into two subtypes , i. e. tropical seasonal rain forest in the lowlands and tropical montane rain forest on higher elevations. The tropical seasonal rain forest in this region shows similar forest profile and physiognomic characteristics to those of equatorial lowland rain forests and is a type of world tropical rain forest. Because of conspicuous similarity on floristic composition , the tropical seasonal rain forest in Xishuangbanna is a type of tropical Asian rain forest . However , since the tropical seasonal rain forest occurs at the northern edge of tropical SE Asia, it differs from typical lowland rain forests in equatorial areas in maintaining some deciduous trees in the canopy layer , fewer megaphanerophytes and epiphytes but more abundant lianas and more plants with microphyll . It is a type of semi-evergreen rain forest at the northern edge of the tropical zone . The tropical montane rain forest occurs in wet montane habitats and is similar to the lower montane rain forests in equatorial Asia in floristic composition and physiognomy . It is a variety of lower montane rain forests at the northern tropical edges of tropical rain forests . The tropical seasonal moist forest occurs on middle and upper limestone mountains and is similar to the tropical montane evergreen broad-leaved forest of the region in physiognomy, but it differs from the latter in floristic composition. The monsoon forest in Xishuangbanna is a tropical deciduous forest under the influence of a strong monsoon climate and is considered to be a transitional vegetation type between tropical rain forest and savanna in physiognomy and distribution. The tropical montane evergreen broad- leaved forest is the main vegetation type in mountain areas . It is dominated by the tree species of Fagaceae , Euphorbiaceae , Theaceae and Lauraceae in majority. It differs from the tropical montane rain forests in lack of epiphytes and having more abundant lianas and plants with compound leaves . It is considered to be a distinct vegetation type in the northern margin of mainland southeastern Asia controlling by a strong monsoon climate, based on its floristic and physiognomic characteristics.     

海南岛热带森林景观类型多样性

依据景观生态学原理,按地貌、气候、土壤、植被和土地利用方式的分异,以带、域、省、区、类型为5个基本单位及亚、组等为辅助单位,组建海南岛热带森林景观类型分类体系。把海南岛热带森林景观作为省级单位,它隶属于全球热带林景观带、亚洲（东方）热带林景观域、中国热带林景观亚域,其下划分为东部潮湿森林景观、西部半干旱森林景观、中南部山地森林景观、热带常绿针叶林景观、热带竹林景观和热带人工林景观6个森林景观区;以热带低地沟谷热带雨林为代表的11个森林景观亚区;以热带低地沟谷龙脑香森林景观为代表的26个森林景观类型组;以热带低地沟谷青皮林为代表的54个森林景观类型。海南岛热带森林景观类型分类体系较全面地表达了海南岛热带森林景观类型多样性。     

论滇南西双版纳的森林植被分类

本文基于多年研究成果的总结,对西双版纳森林植被的分类、主要植被类型及其特征进行了系统归纳,并讨论了它们与世界类似热带森林植被的关系。以群落的生态外貌与结构、种类组成和生境特征相结合作为植被分类的原则和依据,可以将西双版纳的热带森林植被分类为热带雨林、热带季节性湿润林、热带季雨林和热带山地常绿阔叶林四个主要的植被型,包括有至少二十个群系。热带雨林包括热带季节雨林和热带山地(低山)雨林二个植被亚型。热带季节雨林具有与赤道低地热带雨林几乎一样的群落结构和生态外貌特征,是亚洲热带雨林的一个类型,但由于发生在季风热带北缘纬度和海拔的极限条件下,受到季节性干旱和热量不足的影响,在其林冠层中有一定比例的落叶树种存在,大高位芽植物和附生植物较逊色而藤本植物和在叶级谱上的小叶型植物更丰富,这些特征又有别于赤道低地的热带雨林。热带山地雨林是热带雨林的山地亚型,是该地区热带山地较湿润生境的一种森林类型,它在植物区系组成和生态外貌特征上类似于热带亚洲的低山雨林,隶属于广义热带雨林植被型下的低山雨林亚型。热带季节性湿润林分布在石灰岩山坡中、上部,在群落外貌上类似热带山地常绿阔叶林但在植物区系组成上与后者不同,它是石灰岩山地垂直带上的一种植被类型。热带季雨林是分布在该地区开阔河谷盆地及河岸受季风影响强烈的生境的一种热带落叶森林,是介于热带雨林与萨王纳之间的植被类型。热带山地常绿阔叶林(季风常绿阔叶林)是西双版纳的主要山地植被类型,它分布在热带季节雨林带之上偏干的山地生境。它在植物区系组成上不同于该地区的热带季节雨林,在生态外貌特征上亦不同于热带山地雨林,是发育在受地区性季风气候强烈影响的热带山地的一种森林植被类型。     

海南岛霸王岭垂直带热带植被物种多样性的空间分析

以常用的Shannon-Wiener指数,Simpson指数以及新近提出的两个非参数指数(Chao多样性指数和二阶刀切法多样性指数),计测了海南岛霸王岭垂直带上不同植被类型(包括热带低山雨林、热带山地雨林、热带云雾林、热带山地矮林)的物种多样性.在此基础上,借助地理信息系统的空间分析技术,模拟绘制了整个梯度的多样性变化谱.总体而言,样带下部的物种多样性高于上部,或者说热带低山雨林与热带山地雨林的物种多样性高于热带云雾林与热带山地矮林,而南部稍高于北部.这种基于插值方法的空间分析技术为探索植被结构分析提供了一条新的途径.     

Long-term potential for tropical-forest degradation due to deforestation and fires in the Brazilian Amazon

Biome models of the global climate-vegetation relationships indicate that most of the Brazilian Amazon has potential for being covered by tropical forests. From current land-use processes observed in the region, however, substantial deforestation and fire activity have been verified in large portions of the region, particularly along the Arc of Deforestation. In a first attempt to evaluate the long-term potential for tropical-forest degradation due to deforestation and fires in the Brazilian Amazon, we analysed large-scale data on fire activity and climate factors that drive the distribution of tropical forests in the region. The initial analyses and results from this study lead to important details on the relations between these quantities and have important implications for building future parameterizations of the vulnerability of tropical forests in the region.     

Diversity of tropical forest landscape types in Hainan Island, China

A novel landscape classification system was proposed in this study based on landscape ecological theory and the differentiation in climate, topography, soil, vegetation and land use mode. Five basic units (zone, tract, province, region and type) and two assistant units (sub and group) were used in this system. The tropical forest landscape in Hainan Island was regarded as a landscape province, belonging to global tropical forest landscape zone, Asiatic (oriental) tropical forest landscape tract and Chinese tropical forest landscape subtract. Based on the grade system of region, sub-region, type-group and type, this landscape province (Hainan Island) is divided into 6 landscape regions (east moist forest landscape, west semi-arid forest landscape, central-south mountainous forest landscape, tropical evergreen needle-leaved forest landscape, tropical bamboo landscape and tropical plantation landscape), 11 tropical forest landscape sub-regions represented by tropical lowland valley rain forest landscape, 26 tropical forest landscape-type groups represented by tropical lowland valley Dipterocarpaceae forest landscape, and 54 forest landscape types (FLT) represented by lowland valley Vatica mangachapoi forest. Generally, this classification system represents the landscape diversity of the tropical forest in Hainan Island. Further studies are needed to better understand the landscape diversity of Hainan Island.     

Diversity of tropical forest landscape types in Hainan Island, China

A novel landscape classification system was proposed in this study based on landscape ecological theory and the differentiation in climate, topography, soil, vegetation and land use mode. Five basic units (zone, tract, province, region and type) and two assistant units (sub and group) were used in this system. The tropical forest landscape in Hainan Island was regarded as a landscape province, belonging to global tropical forest landscape zone, Asiatic (oriental) tropical forest landscape tract and Chinese tropical forest landscape subtract. Based on the grade system of region, sub-region, type-group and type, this landscape province (Hainan Island) is divided into 6 landscape regions (east moist forest landscape, west semi-arid forest landscape, central-south mountainous forest landscape, tropical evergreen needle-leaved forest landscape, tropical bamboo landscape and tropical plantation landscape), 11 tropical forest landscape sub-regions represented by tropical lowland valley rain forest landscape, 26 tropical forest landscape-type groups represented by tropical lowland valley Dipterocarpaceae forest landscape, and 54 forest landscape types (FLT) represented by lowland valley Vatica mangachapoi forest. Generally, this classification system represents the landscape diversity of the tropical forest in Hainan Island. Further studies are needed to better understand the landscape diversity of Hainan Island.     

滇南热带季雨林的一些问题讨论

通过分析云南南部的水、热条件及植被分布,讨论了季雨林植被类型及其特征,认为云南南部的季雨林是介于热带雨林与萨王纳之间的,在干季基本上是落叶的一种森林植被类型,符合Schimper (1903)定义的热带季雨林植被,并考虑它是一种生态学意义上的经向地带性植被,与该地区的纬向地带性植被热带季节雨林一起共同构成云南南部的水平地带性植被。在云南南部的石灰岩山坡分布的过去被认为是季雨林的森林植被,尽管也受到季节性干旱的影响而不同程度地具有落叶成分,但它在群落外貌上与典型的季雨林不相同,在植物区系组成上也明显不同于该地区非石灰岩山地的季风常绿阔叶林,在分布上亦是在石灰岩低山沟谷的热带季节性雨林水平地带性植被带之上,根据其生态外貌、植物区系组成和生境特点,我们建议用“热带季节性湿润林”来称呼这类石灰岩山地森林类型,在性质上属东南亚热带北缘石灰岩山地垂直带上的一种植被类型。     

武功山地区种子植物区系研究

通过多次野外调查及资料整理,对武功山地区种子植物科、属、种的组成及区系特征进行了调查分析,为该区植物资源的保护以及植物分区提供理论依据。结果表明:(1)武功山地区共有种子植物166科、814属、2 079种,分别占江西省种子植物科、属、种总数的72.81%、61.11%、50.46%,其中裸子植物有7科、15属、19种,分别占江西裸子植物总数的77.78%、65.21%、54.28%。(2)武功山地区科包含12个分布区类型,热带成分占优势(70科,占57.96%),温带成分丰富(46科,38.65%);属包含14个分布区类型,热带成分略占优势(368属,49.40%),温带成分增加(354属,47.53%);种包含14个分布类型,热带分布性626种(31.04%),温带分布性663种(32.87%),温带成分略占优势;武功山地区植物成分具有热带向温带过渡的特点,并且热带和温带成分相互交融、渗透。(3)武功山地区种子植物具有单种和少种的科属较多,具有起源古老的特点,其中单种属有414属,占总属数的50.86%。中国特有成分有4科、23属、728种。(4)与相邻的15个代表性区系比较表明,武功山地区种类较为丰富,聚类分析表明该区系与黄山、庐山、武夷山、井冈山等地区的关系很密切,与秦岭、西双版纳和高黎贡山的区系关系最疏远。     

Ecological relations in the evolution of acanthopterygian fishes in warm-temperate communities of the northeastern Pacific

Synopsis The species composition of acanthopterygian fishes in warm-temperate communities of the northeastern Pacific reflects the influence of ecological relations on teleostean evolution. The species are of either temperate or tropical derivation, with the temperate derivatives (e.g., scorpaeniforms, pleuronectiforms and zoarcoid perciforms) being mostly generalized carnivores, and the tropical derivatives (almost all of them perciforms) ranging from generalized carnivores to a diversity of specialized carnivores and herbivores. The tropical group dominates, with species of the labroid families Pomacentridae, Embiotocidae and Labridae being especially prominent, based mainly on specialized abilities to feed on sessile invertebrates and zooplankters. Other perciforms of tropical stock that do well here include kyphosids, which are herbivores. These trophic capabilities have been inherited from tropical ancestors and are poorly developed among the temperate derivatives. Despite their successes in warm-temperate habitats, few tropical derivatives have extended their distributions into the cold-temperate region; similarly, temperate derivatives have been to a large extent limited in spreading southward into the warm-temperate region. These limits to distribution cannot be attributed to problems with food resources, but are readily explained by effects of surface currents on early life-history stages in this coastal upwelling system.     

西双版纳森林植被研究

西双版纳是世界生物学多样性保护的关键和热点地区,倍受国际学术界的关注。笔者依据30多年来对西双版纳植被的调查,结合植物群落生态学与植物区系地理学研究,并参考世界类似热带植被的研究成果,对西双版纳植被的分类、物种组成、群落生态表现和植物区系特征等作了系统探讨,还进一步分析比较了其与世界类似热带森林植被的关系。结果显示,西双版纳的森林植被共包括32个较为典型的群系,且分属于7个主要的植被型,即热带雨林、热带季节性湿润林、热带季雨林、热带山地(低山)常绿阔叶林、热带棕榈林、暖热性针叶林和竹林。本文对西双版纳植被进行的全面记录和系统归纳,可为科学研究、生物多样性保护和自然保护区的管理提供参考。     

论季雨林的水平地带性

季雨林是受制于湿度因子的经度地带性植被类型,它是随着湿度条件的下降由热带雨林向热带疏林过渡的居间类型,而不是受制于温度因子的纬度地带性植被类型,不是随着温度条件的下降由热带雨林向亚热带常绿阔叶林过渡的居间类型。我国南亚热带的榕树群系、黄桐群系,以及热带北缘的青皮群系均不应是季雨林,前二者是典型的南亚热带低地常绿阔叶林或南亚热带雨林,后者则是热带雨林的一分类群。     

中国外来入侵植物区系组成的大尺度格局及其气候解释

外来入侵物种的空间分布格局及其影响因子的研究是外来物种管理和控制的基础。本研究利用文献数据和气候资料,探讨了中国外来人侵植物（属）区系组成的大尺度格局及其与气候因子之间的联系。从植物区系的总体构成来看,热带区系成分所占比重较大,其次为温带成分和世界分布成分,说明研究区域内外来人侵植物主要起源于热带地区,其次为温带地区。从空间格局来看,从南到北,热带区系成分所占比重呈递减趋势,而温带区系成分所占比重则呈递增趋势。这说明,在南部区域,外来入侵植物更多的来自于热带地区,但在北部区域,来自于温带地区的外来入侵植物可能占据主导地位。热量水平显著影响外来入侵植物的空间格局,随着热量水平的提高,热带区系比重呈递增趋势,而温带区系成分所占比重则呈递减趋势,这可能与不同区系成分植物的生态特性有关。     

Fish larvae assemblages in the Gulf of California

The distributional diversity and assemblages of fish larvae in the Gulf of California indicated two main seasonal stages and two transitional periods: in winter, the tropical water mass is confined to the south‐east portion of the mouth of the Gulf and larval fish assemblages are dominated by subtropical and temperate‐subarctic species; in summer; tropical water invades the Gulf and assemblages are dominated by tropical species. Both seasonal stages are separated by transitional periods coinciding with strong latitudinal temperature gradients. During the autumn and spring transitional periods, the Gulf of California splits into three regions: a northern region where temperate and subarctic species spawn from autumn to spring, a southern region dominated by tropical and subtropical species year round and a central region where tropical and temperate assemblages merge. Seasonal changes in the location of the regions, as well as the borders between them, show expansion and contraction of the northern and southern faunas related to the general oceanic circulation patterns during the year.     

Artificial nest predation rates in tropical and temperate forests: a review of the effects of edge and nest site

Nest predation rates are believed to be higher in tropical than in temperate forests. This notion is central in explaining different life history traits of tropical and temperate birds, but it is not known whether this assertion is true for all nest sites, such as ground and shrub nests, and at different distances from forest edge. I reviewed 22 studies using artificial nest experiments which concurrently contrasted predation rates of ground and shrub nests in temperate and tropical forests and found, contrary to the current dogma, no overall difference in predation rates between regions. However, there was a significant interaction between region and nest site. Ground nest predation rates were significantly higher in the tropical region, while predation rates on shrub nests were similar between regions. Within the tropical region, ground nests had significantly higher predation rates than shrub nests. Elevated nest predation rates at forest edges were found in both temperate and tropical forests. The results may have great implications for expected patterns of avian life histories and for the effects of forest fragmentation in temperate and tropical regions. First, if nest predation affects avian life histories, my results predict ground-nesting species in tropical forests to have shorter nestling periods, more broods and smaller clutch sizes than shrub-nesting species. Second, vulnerability of ground- and shrub-nesting guilds is suggested to differ between regions due to differences in forest vegetation structure, and the composition of predator faunas and their specific responses to forest fragmentation. Data to test these hypotheses are limited, but agree with the results of this review.     

Geological History,Flora, and Vegetation of Xishuangbanna,Southern Yunnan,China1

Xishuangbanna of southern Yunnan is biogeographically located at a transitional zone from tropical Southeast (SE) Asia to subtropical East Asia, and is at the junction of the Indian and Burmese plates of Gondwana and the Eurasian plate of Laurasia. The flora of the region consists of a recorded 3336 native seed plant species, belonging to 1140 genera in 197 families, among which 83.5 percent are tropical genera and 32.8 percent are endemic to tropical Asia, suggesting a strong affinity to tropical Asian flora. The vegetation of Xishuangbanna is organized into four forest types: tropical rain forest, tropical seasonal moist forest, tropical montane evergreen broad‐leaved forest, and tropical monsoon forest. The tropical rain forest in Xishuangbanna has the same floristic composition of families and genera as some lowland equatorial rain forests in SE Asia, and is dominated (with a few exceptions) by the same families both in species richness and stem dominance. The exceptions include some deciduous trees in the canopy layer, fewer megaphanerophytes and epiphytes, and a higher abundance of lianas and microphyllic plants. We consider the tropical rain forest of Xishuangbanna as a type of tropical Asian rain forest, based on their conspicuous similarities in ecological and floristic characteristics.     

The effects of disturbance on forest structure and diversity at different altitudes in Garhwal Himalaya

The effects of disturbance on forest structure and diversity along an altitudinal gradient in the temperate, sub-tropical, and tropical regions of Garhwal Himalaya were assessed. Each region was further categorized into undisturbed (UD), mildly disturbed (MD), and highly disturbed (HD) sites on the basis of magnitude of disturbance in these forests. On UD sites of temperate, sub-tropical and tropical regions, Quercus leucotrichophora, Anogeissus latifolia and Holoptelea integrifolia were the dominant tree species respectively. The highest values of tree density (1028 ind*hm-2) and total basal cover at breast height (31.70 m2 *hm-2) were recorded for UD site of temperate region, whereas maximum species diversity (3.128) and equitability (14.09) values were observed for HD site of tropical region. The structure and composition of the forests were greatly affected by the degree of disturbance.     

Patterns of molecular evolution associated with two selective sweeps in the Tb1-Dwarf8 region in maize

We focused on a region encompassing a major maize domestication locus, Tb1, and a locus involved in the flowering time variation, Dwarf8 (D8), to investigate the consequences of two closely linked selective sweeps on nucleotide variation and gain some insights into maize geographical diffusion, through climate adaptation. First, we physically mapped D8 at approximately 300 kb 3' of Tb1. Second, we analyzed patterns of nucleotide variation at Tb1, D8, and seven short regions (400-700 bp) located in the Tb1-D8 region sequenced on a 40 maize inbred lines panel encompassing early-flowering temperate and late-flowering tropical lines. The pattern of polymorphism along the region is characterized by two valleys of depleted polymorphism while the region in between exhibits an appreciable amount of diversity. Our results reveal that a region approximately 100 kb upstream of the D8 gene exhibits hallmarks of divergent selection between temperate and tropical lines and is likely closer than the D8 gene to the target of selection for climate adaptation. Selection in the tropical lines appears more recent than in the temperate lines, suggesting an initial domestication of early-flowering maize. Simulation results indicate that the polymorphism pattern is consistent with two interfering selective sweeps at Tb1 and D8.     

Spatial patterns and recent trends in the climate of tropical rainforest regions

We present an analysis of the mean climate and climatic trends of tropical rainforest regions over the period 1960-1998, with the aid of explicit maps of forest cover and climatological databases. Until the mid-1970s most regions showed little trend in temperature, and the western Amazon experienced a net cooling probably associated with an interdecadal oscillation. Since the mid-1970s, all tropical rainforest regions have experienced a strong warming at a mean rate of 0.26 +/- 0.05 degrees C per decade, in synchrony with a global rise in temperature that has been attributed to the anthropogenic greenhouse effect. Over the study period, precipitation appears to have declined in tropical rainforest regions at a rate of 1.0 +/- 0.8% per decade (p < 5%), declining sharply in northern tropical Africa (at 3-4% per decade), declining marginally in tropical Asia and showing no significant trend in Amazonia. There is no evidence so far of a decline in precipitation in eastern Amazonia, a region thought vulnerable to climate-change-induced drying. The strong drying trend in Africa suggests that this should be a priority study region for understanding the impact of drought on tropical rainforests. We develop and use a dry-season index to study variations in the length and intensity of the dry season. Only African and Indian tropical rainforests appear to have seen a significant increase in dry-season intensity. In terms of interannual variability, the El Niño-Southern Oscillation (ENSO) is the primary driver of temperature variations across the tropics and of precipitation fluctuations for large areas of the Americas and southeast Asia. The relation between ENSO and tropical African precipitation appears less direct.     

Mitogenomic Evidence for an Indo-West Pacific Origin of the Clupeoidei (Teleostei: Clupeiformes)

The clupeoid fishes are distributed worldwide, with marine, freshwater and euryhaline species living in either tropical or temperate environments. Regional endemism is important at the species and genus levels, and the highest species diversity is found in the tropical marine Indo-West Pacific region. The clupeoid distribution follows two general pattern of species richness, the longitudinal and latitudinal gradients. To test historical hypotheses explaining the formation of these two gradients, we have examined the early biogeography of the Clupeoidei in reconstructing the evolution of their habitat preferences along with their ancestral range distributions on a time-calibrated mitogenomic phylogeny. The phylogenetic results support the distinction of nine main lineages within the Clupeoidei, five of them new. We infer several independent transitions from a marine to freshwater environment and from a tropical to temperate environment that occurred after the initial diversification period of the Clupeoidei. These results combined with our ancestral range reconstruction hypothesis suggest that the probable region of origin and diversification of the Clupeoidei during the Cretaceous period was the tropical marine precursor to the present Indo-West Pacific region. Thus, our study favors the hypotheses of “Region of origin” and “Tropical conservatism” to explain the origins of the longitudinal and latitudinal gradients of clupeoid species richness, respectively. Additional geological and paleontological evidence further define the tropical marine paleo-region of origin as the eastern Tethys Sea region. The Cretaceous fossil record of the Clupeoidei is partially incongruent with the results here as it contains taxa found outside this region. We discuss three possible causes of conflict between our biogeographical hypothesis and the distributions of the Cretaceous clupeoid fossils: regional extinction, incomplete taxonomic sampling and incorrect timescale estimation.