Patterns of species diversity and phylogenetic structure of vascular plants on the Qinghai‐Tibetan Plateau

Large-scale patterns of species richness and the underlying mechanisms regulating these patterns have long been the central issues in biogeography and macroecology. Phylogenetic community structure is a result of combined effects of contemporary ecological interactions, environmental filtering, and evolutionary history, and it links community ecology with biogeography and trait evolution. The Qinghai-Tibetan Plateau provides a good opportunity to test the influence of contemporary climate on shaping species richness because of its unique geological history, cold climate, and high biodiversity. In this study, based on high-resolution distributions of ˜9000 vascular plant species, we explored how species richness and phylogenetic structure of vascular plants correlate with climates on the highest (and species rich) plateau on the Earth. The results showed that most of the vascular plants were distributed on the eastern part of the plateau; there was a strong association between species richness and climate, even after the effects of habitat heterogeneity were controlled. However, the responses of richness to climate remarkably depended on life-forms. Richness of woody plants showed stronger climatic associations than that of herbaceous plants; energy and water availability together regulated richness pattern of woody plants; whereas water availability predominantly regulated richness pattern of herbaceous plants. The phylogenetic structure of vascular species clustered in most areas of the plateau, suggesting that rapid speciation and environment filtering dominated the assembly of communities on the plateau. We further propose that biodiversity conservation in this area should better take into account ecological features for different life-forms and phylogenetic lineages.     

中国斑腿蝗科特有种的分布及特有分布区划分

按照150km×150km对中国陆地部分进行栅格划分,收集整理了中国斑腿蝗科237个特有种在各栅格的分布信息,建立了物种(237)×栅格(168)数据矩阵,研究了中国斑腿蝗科特有种的分布规律并用PAE法进行特有分布区划分。结果表明:除天山山地分布的少数几个种外,中国斑腿蝗科特有种基本分布西南-东北走向。在该范围内南多北少。华南和西南是中国斑腿蝗科特有种最丰富的地区,在秦巴山区、藏东南和浙闽丘陵地带各有一个高密度的分布区。11个特有分布区中5个分布在东洋界部分,两个在中国东部古北和东洋界交界区,天山山地有一个分散的特有分布区,东北有2个特有分布区。特有分布区的分布和划分基本和中国动物地理区划及区系相一致,但台湾地区归入华中区;横断山和秦岭山地的栅格在支序图中多形成未决分类单元,特有分布区划分困难;华南和华中地区的特有分布区可以进一步划分成更小范围的特有分布区;从云南西北的腾冲、保山经过贵州南部到广西桂林的一个东西狭长的区域可以作为一个特有分布区     

云南蕨类植物的物种多样性和区系组成

在一定实地调查和分类的基础上,采用统计分析及区系地理分析法,对云南地区蕨类植物进行研究。结果表明:云南地区共有蕨类植物60科193属1 530种(包括变种和变型),科、属、种分别占中国蕨类植物科总数的58.8%,属的83.9%和种的95.2%;在这60个科中含30种以上的有13个,含5个属以上的有11个,分别占该蕨类植物区系属、种数的56.5%和79.2%,特别是鳞毛蕨科、蹄盖蕨科、水龙骨科和金星蕨科,这4个科共拥有70属761种,分别占总属数、总种数的36.3%、49.7%;193属中含30种以上的有11个,分别占总属、总种数的5.7%和41.7%,最具优势的是鳞毛蕨属和耳蕨属、蹄盖蕨属、铁角蕨属、卷柏属,这5个属共有403种,占总种数的26.3%;该区系中无云南特有科,但具有4个亚洲特有科:雨蕨科、稀子蕨科、柄盖蕨科和骨碎补科;该区系以热带、亚热带性质为主,科的区系成分中热带亚热带分布的科占66.6%,热带成分的属有112个,占68.7%(除世界分布类型);该区系是东亚地区蕨类植物区系的重要组成部分,东亚分布31属和中国特有分布6属,分别占总属数(除世界分布属外)的19.0%和3.7%;该地区蕨类植物区系与西藏、台湾具有共同的区系起源和物种分化形成的背景,属的相似性系数约为70%,种的相似性系数约为30%,均起源于热带亚热带地区;属的热带区系成分与温带区系成分所占比例分别为68.7%和27.6%,存在一定的区系过渡性;该区系科的分化强度为3.2,属的分化强度为7.9,在科、属水平上均表现出较强的区系分化特征。     

Community assembly along a successional gradient in sub‐alpine meadows of the Qinghai‐Tibetan Plateau,China

Community assembly is a dynamic progression that reflects the interaction of several processes functioning at multiple scales. Understanding how these processes work in communities at different successional stages is important for identifying when regional or local processes are more important for community assembly, and for developing effective preservation and restoration strategies. We examined community assembly using a chronosequence of sub‐alpine meadows in Qinghai‐Tibetan Plateau that range from ‘natural’ (never farmed), to those that have been protected from agricultural exploitation for 1 to 10 years. We tested for shifts in species and traits among meadows and also for changes in environmental and spatial correlates of species distributions within meadows. We found that species richness increased and species composition returned to natural conditions within ten years of protection. These changes coincided with shifts in species traits; abundant species had high seed mass and specific leaf area in late‐successional meadows, whereas the opposite occurred in early‐successional meadows. Despite these shifts among meadows of different ages, spatial distributions of species within meadows did not change – when associated with abiotic variables, these spatial patterns reflected changes in soil pH and nitrogen. There was also no consistent change in the relative importance of environmental and spatial correlates of species distributions within meadows. These trends indicate that local processes of community assembly are similar within meadows even when species in those meadows differ. We conclude that successional change is a large‐scale process that alters the species pool and resulting suite of traits that are present within meadows. As a result, regional planning that incorporates successional age should be the focus for the conservation of diversity in this area. In contrast, local processes work within the constraints of the species pool set by successional age, producing consistent patterns within meadows of different ages.     

An assessment of endemism and species richness patterns in the Australian Anura

Aim To assemble a continental‐scale data set of all available anuran records and investigate trends in endemism and species richness for the Anura. Location Continental Australia. Methods 97,338 records were assembled, covering 75% of the continent. A neighbourhood analysis was applied to recorded locations for each species to measure richness and endemism for each half‐degree grid square (c. 50 km) in the continent. This analysis was performed for all anurans, and also for each of the three main anuran families found in Australia. A Monte Carlo simulation was used to test a null hypothesis that observed centres of endemism could result simply from an unstructured overlapping of species ranges of different sizes. Results Eleven main centres of anuran endemism were identified, the most important being the Wet Tropics and the south‐west near Bunbury‐Augusta and near Walpole. With the exception of south‐western Australia, all of the identified significant endemic centres are in the northern half of the continent. The regions identified as significant for endemism differed from those identified for species richness and are more localized. Species richness is greatest in the Wet Tropics and the Border Ranges. High species richness also occurs in several areas not previously identified along the east and northern coasts. Main conclusions Weighted endemism provides a new approach for determining significant areas for anuran conservation in Australia and areas can be identified that could be targeted for beneficial conservation gains. Patterns in endemism were found to vary markedly between the three main anuran families, and south‐eastern Australia was found to be far less significant than indicated by previous studies. The need for further survey work in inland Australia is highlighted and several priority areas suggested. Our results for species richness remain broadly consistent with trends previously observed for the Australian Anura.     

Biogeographical analysis of rodent endemism and distributional congruence in the southern–central Andes (north‐western Argentina)

The recognition of areas of endemism (AEs) is important for conservation biology and biogeographical regionalization. Our objective was to quantitatively identify AEs and distributional congruence patterns of native rodents at the tropical/temperate transition in the central Andes. We analysed 6200 geo‐referenced distributional records of 80 species in north‐western Argentina using NDM/VNDM software. We found 20 AEs defined by 22 endemic species (27% of the total rodent fauna) and 34 patterns of distributional congruence in non‐endemic rodents. Geographical range congruence follows two main patterns running parallel along the Andes. One is related to the humid eastern slopes of the Andes (Argentinean Yungas forest) and the other to the high Andes (Argentinean Puna plateau). Endemism was mainly restricted to the southernmost part of the Yungas forest and adjacent dryer valleys (Monte desert). Species diversity was highest in the northern sector of the Argentinean Yungas forest, where several species reach their southern distributional range. This incongruence among hotspots of diversity and endemism has also been also noted in diversity studies at continental and global scales. Our results provide a starting point for conservation planning in the southernmost Central Andes, which combines the taper of tropical diversity and range‐restricted species endemic to the tropical–temperate transition. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 163–179.     

关于浙江南部森林植物华南,华东两个区系的划分问题

选取分布于浙江南部的１１６个华南森林植物区系成份的工表种。根据自然地理条件的异同,在浙江南部的温州地区和丽水地区中选择５个代表性区域,分析其与华南区系的亲缘关系,在此基础上提出本区内华南,华东两个区系的划分意见,以乐清湾的清江为起点,向东越过乐清湾至温岭县南端（坞根）,再经石头桥至交陈而出东海,向西南则沿北雁荡山东南山麓地带经永嘉县南端（上塘）至青田县东端（温溪）,再越过瓯江向东南拐弯至瓯海（瞿溪     

Responses of forest eucalypts to moderate and high intensity fire in the Tingle Mosaic,south‐western Australia: comparisons between locally endemic and regionally distributed species

Responses of three locally endemic (Eucalyptus brevistylis, Eucalyptus jacksonii and Eucalyptus guilfoylei) and three co‐occurring regional eucalypts (Eucalyptus marginata, Eucalyptus diversicolor and Corymbia calophylla) to moderate‐ and high‐intensity fires were examined in granitic terrain of the Tingle Mosaic, south‐western Australia. Significant associations between diameter distributions and community type (CT) for each species (P < 0.001) suggest that fire response will also vary according to the habitat/fire interaction. None of the species were fire sensitive, although responses differed both within and between species, and with CT. All species examined predominately consisted of several cohorts of regeneration within a forest stand. Each species had thick bark and re‐sprouted from crown epicormics following 100% scorch of the mature tree. The quantity and type of regeneration in relation to gaps created by individual dead trees following fire differed between species; for example, E. guilfoylei regeneration was strongly associated with gaps, and C. calophylla with non‐gaps. However, regeneration of the two tall open‐forest species, E. jacksonii and E. diversicolor were not most associated with either gaps or non‐gaps. The very low levels of regeneration of E. brevistylis following fire and the high proportion of stems of E. jacksonii that were hollow butted (40% of stems > 1 m DBHOB) may be factors associated with narrow endemism of these species and may affect the vulnerability of these eucalypts to fire. The interaction of seed availability, intense fires and subsequent rainfall may be critical in the long term survival of these species. Eucalyptus guilfoylei, by contrast, appears well adapted to the increasing levels of disturbance likely in the region where these species occur. The vulnerability of a locally endemic species in a fire‐prone environment is likely to reflect differences to the prevailing adaptations of the dominant species rather than an inherent ability of the species to survive or respond. Management regimes must account for variations in species responses to fire in different CTs if the long‐term survival chances of local endemics are to be enhanced.     

Experimental warming causes large and rapid species loss, dampened by simulated grazing, on the Tibetan Plateau

We investigated the independent and combined effects of experimental warming and grazing on plant species diversity on the north‐eastern Tibetan Plateau, a region highly vulnerable to ongoing climate and land use changes. Experimental warming caused a 26–36% decrease in species richness, a response that was generally dampened by experimental grazing. Higher species losses occurred at the drier sites where N was less available. Moreover, we observed an indirect effect of climate change on species richness as mediated by plant–plant interactions. Heat stress and warming‐induced litter accumulation are potential explanations for the species’ responses to experimental warming. This is the first reported experimental evidence that climate warming could cause dramatic declines in plant species diversity in high elevation ecosystems over short time frames and supports model predictions of species losses with anthropogenic climate change.     

Altitudinal biodiversity patterns of seed plants along Gongga Mountain in the southeastern Qinghai–Tibetan Plateau

The mechanisms underlying elevation patterns in species and phylogenetic diversity remain a central issue in ecology and are vital for effective biodiversity conservation in the mountains. Gongga Mountain, located in the southeastern Qinghai–Tibetan Plateau, represents one of the longest elevational gradients (ca. 6,500 m, from ca. 1,000 to 7,556 m) in the world for studying species diversity patterns. However, the elevational gradient and conservation of plant species diversity and phylogenetic diversity in this mountain remain poorly studied. Here, we compiled the elevational distributions of 2,667 native seed plant species occurring in Gongga Mountain, and estimated the species diversity, phylogenetic diversity, species density, and phylogenetic relatedness across ten elevation belts and five vegetation zones. The results indicated that species diversity and phylogenetic diversity of all seed plants showed a hump‐shaped pattern, peaking at 1,800–2,200 m. Species diversity was significantly correlated with phylogenetic diversity and species density. The floras in temperate coniferous broad‐leaved mixed forests, subalpine coniferous forests, and alpine shrublands and meadows were significantly phylogenetically clustered, whereas the floras in evergreen broad‐leaved forests had phylogenetically random structure. Both climate and human pressure had strong correlation with species diversity, phylogenetic diversity, and phylogenetic structure of seed plants. Our results suggest that the evergreen broad‐leaved forests and coniferous broad‐leaved mixed forests at low to mid elevations deserve more conservation efforts. This study improves our understanding on the elevational gradients of species and phylogenetic diversity and their determinants and provides support for improvement of seed plant conservation in Gongga Mountain.     

Comparative phylogeography of five avian species: implications for Pleistocene evolutionary history in the Qinghai‐Tibetan plateau

Pleistocene climate fluctuations have shaped the patterns of genetic diversity observed in extant species. In contrast to Europe and North America where the effects of recent glacial cycles on genetic diversity have been well studied, the genetic legacy of the Pleistocene for the Qinghai‐Tibetan (Tibetan) plateau, a region where glaciation was not synchronous with the North Hemisphere ice sheet maxima, remains poorly understood. Here, we compared the phylogeographical patterns of five avian species on the Qinghai‐Tibetan plateau by three mitochondrial DNA fragments: the Tibetan snow finch (Montifringilla adamsi), the Blanford’s snow finch (Pyrgilauda blanfordi), the horned lark (Eremophila alpestris), the twite (Carduelis flavirostris) and the black redstart (Phoenicurus ochruros). Our results revealed the three species mostly distributed on the platform region of the plateau that experienced population expansion following the retreat of the extensive glaciation period (0.5–0.175 Ma). These results are at odds with the results from avian species of Europe and North America, where population expansions occurred after Last Glacial Maximum (LGM, 0.023–0.018 Ma). A single refugium was identified in a restricted semi‐continuous area around the eastern margin of the plateau, instead of multiple independent refugia for European and North American species. For the other two species distributed on the edges of the plateau (the twite and black redstart), populations were maintained at stable levels. Edge areas are located on the eastern margin, which might have had little or no ice cover during the glaciation period. Thus, milder climate may have mitigated demographic stresses for edge species relative to the extremes experienced by platform counterparts, the present‐day ranges of which were heavily ice covered during the glaciation period. Finally, various behavioural and ecological characteristics, including dispersal capacities, habitat preference and altitude specificity along with evolutionary history might have helped to shape different phylogeographical structures appearing in these five species.     

The coincidence of rarity and richness and the potential signature of history in centres of endemism

We investigate the relative importance of stochastic and environmental/topographic effects on the occurrence of avian centres of endemism, evaluating their potential historical importance for broad‐scale patterns in species richness across Sub‐Saharan Africa. Because species‐rich areas are more likely to be centres of endemism by chance alone, we test two null models: Model 1 calculates expected patterns of endemism using a random draw from the occurrence records of the continental assemblage, whereas Model 2 additionally implements the potential role of geometric constraints. Since Model 1 yields better quantitative predictions we use it to identify centres of endemism controlled for richness. Altitudinal range and low seasonality emerge as core environmental predictors for these areas, which contain unusually high species richness compared to other parts of sub‐Saharan Africa, even when controlled for environmental differences. This result supports the idea that centres of endemism may represent areas of special evolutionary history, probably as centres of diversification.     

Examining differences in phylogenetic composition enhances understanding of the phylogenetic structure of the shrub community in the northeastern Qinghai‐Tibetan Plateau

Periodic climatic oscillations and species dispersal during the postglacial period are two important causes of plant assemblage and distribution on the Qinghai‐Tibet Plateau (QTP). To improve our understanding of the bio‐geological histories of shrub communities on the QTP, we tested two hypotheses. First, the intensity of climatic oscillations played a filtering role during community structuring. Second, species dispersal during the postglacial period contributed to the recovery of species and phylogenetic diversity and the emergence of phylogenetic overdispersion. To test these hypotheses, we investigated and compared the shrub communities in the alpine and desert habitats of the northeastern QTP. Notably, we observed higher levels of species and phylogenetic diversity in the alpine habitat than in the desert habitat, leading to phylogenetic overdispersion in the alpine shrub communities versus phylogenetic clustering in the desert shrub communities. This phylogenetic overdispersion increased with greater climate anomalies. These results suggest that (a) although climate anomalies strongly affect shrub communities, these phenomena do not act as a filter for shrub community structuring, and (b) species dispersal increases phylogenetic diversity and overdispersion in a community. Moreover, our investigation of the phylogenetic community composition revealed a larger number of plant clades in the alpine shrub communities than in the desert shrub communities, which provided insights into plant clade‐level differences in the phylogenetic structures of alpine and desert shrub communities in the northeastern QTP.     

The biogeography and phylogeny of schizothoracine fishes (Schizopygopsis) in the Qinghai‐Tibetan Plateau

Freshwater fish belonging to the genus Schizopygopsis are widespread in drainages throughout the Qinghai‐Tibetan Plateau and, thus, a model group with which to investigate how paleo‐drainage changes linked to historical uplifting within the Qinghai‐Tibetan Plateau influence speciation. To date, the phylogenetic and taxonomic relationships within Schizopygopsis remain controversial. In this study, we constructed a comprehensive molecular phylogeny of Schizopygopsis based on six mitochondrial gene sequences. We compared the taxonomic relationships revealed by this phylogeny with those obtained from morphological data. We also used this phylogeny to assess the extent to which the evolution of Schizopygopsis has been driven by paleo‐drainage changes linked to uplifting of the Qinghai‐Tibetan Plateau. Results indicated that all Schizopygopsis taxa formed a monophyletic group comprising five major clades, which were inconsistent with the taxonomic relationships based on morphology for this group. Our results also strongly supported the validity of S. anteroventris and S. microcephalus as distinct species within Schizopygopsis. Molecular calibrations showed that species within the middle Yangtze species diverged earlier (~4.5 Mya) than species within the Indus River (~3.0 Mya), the Mekong River (~2.8 Mya) and the Tsangpo + Salween rivers (~2.5 Mya). The most recent evolutionary splits occurred among species from the upper and lower Yangtze River, the Yellow River and the Qiadam Basin at about 1.8 to 0.3 Mya. Our molecular evidence and use of the molecular clock calibration have allowed us to associate speciation events within the genus Schizopygopsis to the formation and separation of paleo‐drainage connections caused by tectonic events during the uplifting of the Qinghai‐Tibetan Plateau (~4.5 Mya). This work underlines the dominant role of vicariance in shaping the evolutionary history of the genus Schizopygopsis. Further research using multiple loci and more extensive sampling will reveal a more complete picture of the phylogenetic relationships and biogeography of Schizopygopsis fishes.     

An evaluation of government‐recommended stocking systems for sustaining pastoral businesses and ecosystems of the Alpine Meadows of the Qinghai‐Tibetan Plateau

China introduced the “Retire Livestock and Restore Grassland” policy in 2003. It was strengthened in 2011 by additional funding for on‐farm structures. On the Qinghai‐Tibetan Plateau (QTP), fences were erected, livestock excluded from degraded areas, rotational stocking introduced, nighttime shelters were built, forages grown, and seed sown. However, the effectiveness of these actions and their value to Tibetan herders has been questioned. We conducted a sheep stocking experiment for 5 years in an Alpine Meadow region of the QTP to evaluate stocking options recommended by Government. Cold and warm season stocking each at three rates (0, 8, and 16 sheep/ha) and continuous stocking at 0 and 4 sheep/ha were compared. We measured live weights of sheep, plant species richness and evenness, root biomass and carbon (C), nitrogen (N) and phosphorus (P) contents of the 0–10 cm of soil. We found that resting grassland from stocking during the warm season for later cold season stocking significantly reduced plant species richness and evenness and root biomass but not soil C, N, and P. During cold season stocking, live weights of sheep declined whether at a stocking rate of 8 or 16 per ha. In contrast, sheep continuously stocked on grassland at 4 per ha gained weight throughout both the warm and cold seasons and plant species richness and evenness were maintained. Warm season stocking at 8 and 16 sheep/ha increased plant species richness and root biomass but reduced plant species evenness. Resting these alpine grasslands from stocking in the warm season has adverse consequences for plant conservation. Fencing from stocking in the warm season is not justified by this study; all grassland should be judiciously stocked during the warm season to maintain plant species richness. Neither resting nor stocking during the cold season appears to have any adverse consequences but sheltering and in‐door feeding of sheep during the cold season may be more profitable than cold season stocking with use of open nighttime yards.     

Density and species diversity of trees in four tropical forests of the Albertine rift, western Uganda

We assessed tree species density and diversity in 12 1‐ha plots in four forests of the Albertine rift, western Uganda. There were 5747 trees of diameter ≥ 10 cm in 53 families, 159 genera, and 212 species. Density ranged between 344 and 557 trees ha^?1 (average 479 trees ha^?1). Tree species diversity was highest in the Bwindi and Budongo forests. The Euphorbiaceae family was the most species rich (25 species) followed by Rubiaceae and Meliaceae with 16 species each. Canonical Correspondence Analysis (CCA) showed that major gradients in environmental variables influenced tree species distribution. Sample scores on ordination axes 1 and 2 were strongly correlated with pH and altitude, respectively. Correlated with rainfall and other soil factors, pH and altitude are presumed to be among the most important in influencing the distribution of tree species in the Albertine rift forests. Strategies that take account of variations in pH and elevation are required to conserve tree species in forests of the Albertine rift.