Use of direct gradient analysis to study the climate-vegetation relationships in Galicia,Spain

This paper reports a bioclimatic analysis of plant species in Galicia, NW Spain. A set of floristic data obtained from 150 plots located at euclimatopes (sites with monitored climate) was analysed using direct gradient analysis and clustering with respect to the 8 climatic variables thought to play a major role in regulating the distribution of the species considered in the study area. Principal component analysis (PCA) and hierarchical clustering were based on a matrix of species by climatic variables. Indicator taxa for the variables were identified on the basis of their Indicator values (Brisse & Grandjouan 1978) and grouped by cluster analysis. The groups produced were compatible with the results of principal component analysis and the frequential analysis of the species, which identified their phytoclimatic nature. The groups were then characterized by determining their climatic positions and indicator values with respect to the chief climatic variables. The first three PCA axes, which were associated with Oceanity, Mean minimum temperatures and the temperature range in the coldest month, together accounted for 97.2% of the variance of the data.     

Evolution, origin and age of lineages in the Californian and Mediterranean floras

This paper addresses some of the conceptual issues involved in the analysis of the age and origin of mediterranean‐climate plant taxa, paying particular attention to three topics: (1) the importance of an explicit time frame in the definition of biogeographical origins, (2) the distinction between the age of traits and the age of taxa, and (3) the idea of mediterranean‐type ecosystems as environmental islands. (1) In California, recent analyses demonstrate that the diversity of species derived from different biogeographical origins is significantly correlated with temperature and precipitation gradients. These patterns support the hypothesis that niche conservatism is an important factor structuring modern diversity gradients. However, depending on how far back in time one looks, a species may be assigned to different origins; future discussions of biogeographical origins need to address the appropriate time frame for analysis. (2) Past research has demonstrated distinctive trait syndromes among woody plants of the Mediterranean, Chile, California and Mexico, and proposed that the syndromes are associated with lineages of different age in these floras. Reanalysis of individual traits demonstrates greater variability among regions than previously reported. The classification of plants into ‘old’ and ‘new’ genera is re‐evaluated, and it is suggested that greater attention be paid to the age of traits, rather than to the age of taxa, especially at an arbitrary rank such as genus. (3) The idea of mediterranean‐climate regions as ‘climatic islands’ is examined. Space–time diagrams of climate enable one to view the emergence of distinctive climatic regions in a continental context. The terms ‘synclimatic’ and ‘anticlimatic’ are proposed, referring to migration routes that parallel climate contours in space and time versus those that cross contours (including the case of geographic stasis in the face of climate change), respectively. Mediterranean‐climate regions have served as important case studies in plant ecology and evolution, and merit continued close examination in the light of continued advances in phylogenetics and palaeoecology.     

The performance of models relating species geographical distributions to climate is independent of trophic level

Species–climate ‘envelope’ models are widely used to evaluate potential climate change impacts upon species and biodiversity. Previous studies have used a variety of methods to fit models making it difficult to assess relative model performance for different taxonomic groups, life forms or trophic levels. Here we use the same climatic data and modelling approach for 306 European species representing three major taxa (higher plants, insects and birds), and including species of different life form and from four trophic levels. Goodness‐of‐fit measures showed that useful models were fitted for >96% of species, and that model performance was related neither to major taxonomic group nor to trophic level. These results confirm that such climate envelope models provide the best approach currently available for evaluating reliably the potential impacts of future climate change upon biodiversity.     

Refining vegetation simulation models: From plant functional types to bioclimatic affinity groups of plants

Question: How to refine simulations based on a global vegetation model in order to apply it to regional scale? Location: Europe from 35° N to 71° N and 25° W to 70° E. Methods: Geographical ranges of European plants were georeferenced and used with monthly mean climatic data (diurnal temperature ranges, ground frost frequencies, precipitation, relative humidity, rain frequencies, amount of sunshine hours and temperature) and growing degree days to infer climatic boundaries for 320 taxa. We performed a discriminant analysis to define their potential geographic ranges. Hierarchical clustering was computed on potential ranges. Results: Clustering provided 25 Bioclimatic Affinity Groups (BAG) of plants consisting of 13 tree, seven shrub and five herb groups. These B AGs are characterized by different geographical ranges and climatic tolerances and requirements. Conclusion: The use of monthly data instead of annual values improved the prediction of potential distribution ranges and highlighted the importance of climate seasonality for defining the plant groups with accuracy. The B AGs are detailed enough to provide finer reconstructions and simulations of the vegetation at the regional scale.     

Evolution of the realized climatic niche in the genus Arabidopsis (Brassicaceae)

The evolution of the realized climatic niche in the genus Arabidopsis was studied using an almost complete phylogenetic tree based on DNA sequences of the ribosomal internal transcribed spacers. The realized climatic niche (climate space) was determined by the intersections of the distribution ranges of the taxa with climate data and is presented in temperature/precipitation diagrams. A positive correlation exists between the climate spaces of the taxa and their range sizes. The diagrams revealed a core climate; that is, a climate space in which all taxa co-exist. This core climate is almost identical to the most parsimonious reconstruction of the genus' ancestral climate space and may be considered an ancestral state of these characters. Mapping the evolutionary changes occurring in the realized climatic space on the phylogenetic tree from the core climate proved to be the most parsimonious procedure. The character complex is homoplastic; that is, many parallel evolutionary events have occurred in the subclades. With the exception of A. thaliana, which is sister to the other species of the genus and occupies a very large climate space, the late-diverged taxa of the other subclades experienced great evolutionary changes whereas the realized climate space of the taxa that diverged earlier resembles the core climate. The latter also show some parallel contractions in the climate space. It is hypothesized that the diversification of Arabidopsis may have started from small to midsized ranges in a temperate climate.     

Mexical plant phenology: is it similar to Mediterranean communities?

The sclerophyllous, evergreen vegetation found in Mexico under tropical climate is named 'Mexical' (MEX) and presents many traits that have been thought to converge under a Mediterranean climate. Flowering phenology is strongly similar across Mediterranean-type ecosystems (MTEs) and this paper investigates MEX plant phenology in this context. The common history of the vegetation and the differences in the climatic conditions experienced by MEX and MTE taxa provide an ideal scenario to infer the relative importance of natural selection and historical constraints in the phenological response of plants to climatic conditions. This study has involved collecting field and bibliographic data on flowering phenology of MEX communities to detect (1) similarities at the community level between MTEs and MEX, (2) similarities between Tertiary and Quaternary taxa in MTEs and MEX, and (3) similarities between congeneric taxa from MEX and MTEs (taxa sharing a common ancestor but having evolved under different climates). Flowering in MEX does not occur mainly in spring, as in MTEs, but in summer, suggesting a response that maximizes water use in the rainy season. Flowering phenology of MEX species differed from their MTE congeneric species, suggesting that even though a common ancestor is shared, environmental pressures have led to different phenological responses in MEX and MTE plants. The flowering season for species that originated in the Tertiary and Quaternary did not differ in MEX, as expected, because of climatic uniformity along the whole time line. In MTEs, flowering differences between Tertiary and Quaternary species were not congruent, suggesting that the balance between the historical constraints and the selective force of the Mediterranean climate is different among the three MTEs, and a particular explanation is needed for each. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 297–303.     

Impacts of climate change on national biodiversity population trends

Climate change has had well‐documented impacts on the distribution and phenology of species across many taxa, but impacts on species’ abundance, which relates closely to extinction risk and ecosystem function, have not been assessed across taxa. In the most comprehensive multi‐taxa comparison to date, we modelled variation in national population indices of 501 mammal, bird, aphid, butterfly and moth species as a function of annual variation in weather variables, which through time allowed us to identify a component of species’ population growth that can be associated with post‐1970s climate trends. We found evidence that these climate trends have significantly affected population trends of 15.8% of species, including eight with extreme (> 30% decline per decade) negative trends consistent with detrimental impacts of climate change. The modelled effect of climate change could explain 48% of the significant across‐species population decline in moths and 63% of the population increase in winged aphids. The other taxa did not have significant across‐species population trends or consistent climate change responses. Population declines in species of conservation concern were linked to both climatic and non‐climatic factors respectively accounting for 42 and 58% of the decline. Evident differential impacts of climate change between trophic levels may signal the potential for future ecosystem disruption. Climate change has therefore already driven large‐scale population changes of some species, had significant impacts on the overall abundance of some key invertebrate groups and may already have altered biological communities and ecosystems in Great Britain.     

Apport des pollens fossiles d''ombelliferes a la connaissance paléoecologique et paleoclimatique de l''eocene français

Fossil pollen of the Umbelliferae occur frequently and with considerable diversity in Eocene sediments in France. We have been able to recognise 43 forms belonging to 23 genera. The Thanetian II, the Sparnacian, the Marinesian and the Ludian are characterised by particular assemblages. While in the Thanetian II pollen of a very archaic character predominate, the Ludian shows the greatest diversification of the family.

With respect to climate, the Sparnacian warming is confirmed by the appearance of Steganotaenia, a taxon characteristic of the tropical savannah. A drier climatic phase developed in the Marinesian, indicated by the development of Hohenackeria, a mediterranean taxon of xerophilous affinities. The appearance and extension of modern temperate taxa in the Ludian confirm the climatic change at the end of the Eocene.     

Species Richness Patterns and Water-Energy Dynamics in the Drylands of Northwest China

Dryland ecosystems are highly vulnerable to climatic and land-use changes, while the mechanisms underlying patterns of dryland species richness are still elusive. With distributions of 3637 native vascular plants, 154 mammals, and 425 birds in Xinjiang, China, we tested the water-energy dynamics hypothesis for species richness patterns in Central Asian drylands. Our results supported the water-energy dynamics hypothesis. We found that species richness of all three groups was a hump-shaped function of energy availability, but a linear function of water availability. We further found that water availability had stronger effects on plant richness, but weaker effects on vertebrate richness than energy availability. We conducted piecewise linear regressions to detect the breakpoints in the relationship between species richness and potential evapotranspiration which divided Xinjiang into low and high energy regions. The concordance between mammal and plant richness was stronger in high than in low energy regions, which was opposite to that between birds and plants. Plant richness had stronger effects than climate on mammal richness regardless of energy levels, but on bird richness only in high energy regions. The changes in the concordance between vertebrate and plant richness along the climatic gradient suggest that cautions are needed when using concordance between taxa in conservation planning.     

Biogeographical synthesis of Andalusia (southern Spain)

Andalusia is a large territory of almost 90,000 km² in the south of Spain. The marked heterogeneity of its orographic, lithological and climatic features affords its plants and vegetation a high degree of biodiversity. A biogeographical classification for Andalusia is proposed, based on studies of the physical environment, bioclimatic and analysis of the endemic taxa, series and plant communities found in the territory.     

Climate Analysis of Endemic Species-A Novel Method for Quantitative Analysis of Global Climate Change Since Tertiary

There are many extant endemic plants in China, which were widely distributed in the North Hemisphere during Tertiary. The global cooling during the Tertiary caused a series of narrow distribution regions of the plants. Quaternary glaciation invaded most regions of North America and Eurasia where severe destruction was imposed onto vegetation. However, such destruction was lessened in China largely because of specific topographic and geographical and obviously, a number of other conditions accounted for an unusual refugee camp for the relics of plants in China, among which lots of endemic taxa exist. Recently, Chinese endemic species, such as Metaseqouia, Eucommia , have been employed to conduct multi-disciplinary comprehensive studies so as to analyze Tertiary climate changes quantitatively. Meanwhile, a rigorous method, i.e. climate analysis of endemic species (CAES) has come to maturation. This method is characteristic of some generality because it is supposed to be applicable to the endemic species in other regions of the world. CAES is involved in the following aspects: 1. Conduct multidisciplinary studies on living and fossil species of endemic plants and trace their evolutionary courses. 2. Compare fossil species with living one and clarify which is the nearest living relative (NLR) to fossil counterpart. 3. Fossils and their living counterparts (NLR) are supposed to have similar ecological requirements to meet their life cycles. 4. Investigate the geographic distribution of living and fossil plants within the same taxa and ascertain the dynamic changes of their distributions in geological age. 5. Analyze climate factors in the distribution of specific endemic taxa and obtain the data of climatic characters which are suitable for reconstruction of paleoclimate where fossil counterparts lived. 6. Further study the physio-ecology of living species and determinate paleoclimate where fossil counterparts lived. 7. Integrate analysis of the data from steps 4, 5 and 6, and quantitatively reconstruct the climate where fossil and living plants survive.     

Cladistics and the land plants: A response to Robinson

The reconstruction of phylogenetic relationships should be based not on belief but on an explicit and logical analysis of all available characters. Hennigian phylogenetic systematics (cladistics) provides a framework for evaluating putative homologies characterizing particular hierarchical levels, determining relationships of taxa sharing congruent patterns of homologies, and constructing a classification based on this information. Fossils can and should be included in the analysis if enough of the relevant characters are preserved; this is not currently possible for early land plants because of the fragmentary fossil record. To avoid circularity, adaptive and functional considerations should be addressed only after a phylogenetic hypothesis based on patterns on patterns of shared homologies is available.     

Early Miocene repetitive vegetation and climatic changes in the lacustrine deposits of the Rubielos de Mora Basin (Teruel, NE Spain)

Pollen analysis of a Lower Miocene succession from the Rubielos de Mora Basin (NE Spain) has been carried out with the aim of reconstructing the flora, vegetation and climatic changes. Previous paleobotanical studies on these sedimentary rocks and adjacent areas interpreted very diverse climates for the Early Miocene: from humid temperate to dry subtropical. In this study, a rich thermophilous pollen spectrum and a diverse subarid flora including Nitraria, Caesalpiniaceae, Ephedra and Acacia, indicative of a dry subtropical climate are identified. On the other hand, mesothermic taxa with high water requirements are also abundant. Therefore, the pollen assemblages evidence the juxtaposition of very contrasted environments: the presence of subdesertic taxa, typical of plants growing in the lowlands and conditioned by a long warm, dry season, together with others with very high water requirements, needing constant water. This can be explained by the presence of the Rubielos de Mora Lake providing local conditions for developing riparian forests. The vegetation was clearly controlled by the water availability under a subtropical and dry-seasonal climate. Pollen changes along the succession, which coincide with sedimentological changes, are related to climatic variations. Alternation in pollen taxa (thermophilous–dry vs. mesothermic–riparian) reflects the influence of the cyclicity of temperature and precipitation on the lake level and vegetation.     

Reliability of abundance ratios between aeropalynological taxa as indicators of the climate in France

The abundance ratio between two aeropalynological taxa can sometimes give more reliable information about climate than a single taxon, especially in poorly standardized spectra of sediments, mosses or dusts. The reliabilities of 8385 ratios have been computed from 130 taxa observed in a net of 80 annual standardized aeropalynological spectra measured mostly in France. Ten average climatic factors express cold, heat and rain. The reliability of a pollen ratio is the relative frequency (between 0 and 100%) of the ranks, in the range of the climatic factor, where the ratio is more indicative than its two parent taxa. Only 169 out of the 8,385 ratios have a reliability of 80% or more, with one thousand ratios having a reliability of 50% or more. The most reliable ratios are from the less indicative taxa, whereas ubiquitous taxa give generally unreliable ratios. The accuracy and stability of estimates are approximately the same from the ratios as from the single taxa. The use of ratios foreshadows the use of sociological relations between taxa. Sociological processing will be used to transform the intermittent information about the environment given by the observed abundance of taxa into a gradual information given by their probable abundance.     

Historical climate change and speciation: neotropical seasonally dry forest plants show patterns of both tertiary and quaternary diversification

Historical climate changes have had a major effect on the distribution and evolution of plant species in the neotropics. What is more controversial is whether relatively recent Pleistocene climatic changes have driven speciation, or whether neotropical species diversity is more ancient. This question is addressed using evolutionary rate analysis of sequence data of nuclear ribosomal internal transcribed spacers in diverse taxa occupying neotropical seasonally dry forests, including Ruprechtia (Polygonaceae), robinioid legumes (Fabaceae), Chaetocalyx and Nissolia (Fabaceae), and Loxopterygium (Anacardiaceae). Species diversifications in these taxa occurred both during and before the Pleistocene in Central America, but were primarily pre-Pleistocene in South America. This indicates plausibility both for models that predict tropical species diversity to be recent and that invoke a role for Pleistocene climatic change, and those that consider it ancient and implicate geological factors such as the Andean orogeny and the closure of the Panama Isthmus. Cladistic vicariance analysis was attempted to identify common factors underlying evolution in these groups. In spite of the similar Mid-Miocene to Pliocene ages of the study taxa, and their high degree of endemism in the different fragments of South American dry forests, the analysis yielded equivocal, non-robust patterns of area relationships.     

定量分析第三纪以来环境变化的新方法：—特有种气候分析法

1　全球气候变化研究新动向自 2 0世纪 80年代以来 ,全球气候变化研究至今仍方兴未艾。全球气温波动、大气中温室气体丰度变化、气候格局改变、气候带迁移和降水量增减 ,都影响到社会经济的发展和人类生活质量的提高。各国政府对全球气候变化的研究 ,如气候演变的过程、短期和长期气候变化的预测和自然灾害的防治都给予极大关注和财力支持[1] 。目前全球气候变化的研究正向两个方向发展。1.1　加大全球气候变化研究时间尺度 ,从研究当今气候发展到研究地质历史时期气候变化全球气候变化 ,如大气中ＣＯ2 浓度的变化、温度的升降和降水量的变…     

A biogeographical analysis of the European Atlantic lowland heathlands

Questions: What is the climatic envelope of European Atlantic heathlands and the relationship between their floristic geographical variability and climatic parameters? Are the biogeographic patterns extracted from genuine heath plants comparable to those extracted from the accompanying flora? To what extent does the species composition extracted from phytosociological data support the current theory of refuge areas of heath vegetation in southern Atlantic Europe during the Pleistocene ice ages? Location: Atlantic Europe and NW Morocco. Methods: The geographical territory in which Atlantic heathlands occur was divided into 23 sectors following geographic and chorological criteria. A presence–absence table with 333 taxa was then constructed with the available phytosociological data. The taxa were classified into different groups according to their phytosociological affinity. Several types of numerical analysis were performed with this matrix and the climatic data obtained from meteorological sources. Results: Heathlands require a humid and oceanic climate and are limited by cold temperatures in the north and by summer droughts in the south. The highest floristic richness of this vegetation type is found in NW Iberia. Ordinations indicate a strong correlation between floristic composition of biogeographic sector and summer drought (Ios) and thermicity (It). Conclusions: The main climatic factors determining lowland heathland floristic distribution are thermicity and summer drought. The current optimal conditions for heath flora in NW Iberia suggest that there were southern refuges during the Pleistocene ice ages from which northward expansion has taken place.     

定量分析第三纪以来环境变化的新方法——特有种气候分析法

There are many extant endemic plants in China, which were widelydistributed in the North Hemisphere during Tertiary. The global cooling during the Tertiary caused a series of narrow distribution regions of the plants. Quaternary glaciation invaded most regions of North America and Eurasia where severe destruction was imposed onto vegetation. However, such destruction was lessened in China largely because of specific topographic and geographical and obviously, a number of other conditions accounted for an unusual refugee camp for the relics of plants in China, among which lots of endemic taxa exist. Recently, Chinese endemic species, such as Metaseqouia, Eucommia, have been employed to conduct multi-disciplinary comprehensive studies so as to analyze Tertiary climate changes quantitatively. Meanwhile, a rigorous method, i.e. climate analysis of endemic species (CAES) has come to maturation. This method is characteristic of some generality because it is supposed to be applicable to the endemic species in other regions of the world. CAES is involved in the following aspects: 1. Conduct multidisciplinary studies on living and fossil species of endemic plants and trace their evolutionary courses. 2. Compare fossil species with living one and clarify which is the nearest living relative (NLR) to fossil counterpart. 3. Fossils and their living counterparts (NLR) are supposed to have similar ecological requirements to meet their life cycles. 4. Investigate the geographic distribution of living and fossil plants within the same taxa and ascertain the dynamic changes of their distributions in geological age. 5. Analyze climate factors in the distribution of specific endemic taxa and obtain the data of climatic characters which are suitable for reconstruction of paleoclimate where fossil counterparts lived. 6. Further study the physio-ecology of living species and determinate paleoclimate where fossil counterparts lived. 7. Integrate analysis of the data from steps 4, 5 and 6, and quantitatively reconstruct the climate where fossil and living plants survive.     

Toward genetics-based virus taxonomy: comparative analysis of a genetics-based classification and the taxonomy of picornaviruses

Virus taxonomy has received little attention from the research community despite its broad relevance. In an accompanying paper (C. Lauber and A. E. Gorbalenya, J. Virol. 86:3890-3904, 2012), we have introduced a quantitative approach to hierarchically classify viruses of a family using pairwise evolutionary distances (PEDs) as a measure of genetic divergence. When applied to the six most conserved proteins of the Picornaviridae, it clustered 1,234 genome sequences in groups at three hierarchical levels (to which we refer as the "GENETIC classification"). In this study, we compare the GENETIC classification with the expert-based picornavirus taxonomy and outline differences in the underlying frameworks regarding the relation of virus groups and genetic diversity that represent, respectively, the structure and content of a classification. To facilitate the analysis, we introduce two novel diagrams. The first connects the genetic diversity of taxa to both the PED distribution and the phylogeny of picornaviruses. The second depicts a classification and the accommodated genetic diversity in a standardized manner. Generally, we found striking agreement between the two classifications on species and genus taxa. A few disagreements concern the species Human rhinovirus A and Human rhinovirus C and the genus Aphthovirus, which were split in the GENETIC classification. Furthermore, we propose a new supergenus level and universal, level-specific PED thresholds, not reached yet by many taxa. Since the species threshold is approached mostly by taxa with large sampling sizes and those infecting multiple hosts, it may represent an upper limit on divergence, beyond which homologous recombination in the six most conserved genes between two picornaviruses might not give viable progeny.     

The relationship between temporal patterns of wildfires and phytoclimatic regions in Sardinia (Italy)

Abstract

As a precursor to land management and biodiversity conservation, hierarchical landscape classification and mapping has recently received renewed attention. Since climate is the main factor affecting the coarse‐scale spatial distribution of vegetation types, the first step to deal with for developing a hierarchical landscape classification is to categorize the landscape based on the climatic variables that influence the biological systems. Climate also plays an important role in characterizing wildfire regimes. Through its influence on biomass production, climate controls fuel availability. At the same time, climate affects fuel moisture, which is the main determinant for fire ignition and propagation. The influence of climate on coarse‐scale landscape classification and fire regimes invites a comparison of phytoclimatic maps to wildfire data. The main objectives of this paper are: (1) to evaluate the phenological uniqueness of the main phytoclimatic regions of Sardinia (Italy) based on five‐year data (2000–04) of SPOT‐Vegetation NDVI profiles, and (2) to evaluate to what extent the wildfire time series associated to the phytoclimatic regions of Sardinia differ in their temporal properties over the same time span.