Classification and ordination of plant communities along an altitudinal gradient on the Presidential Range,New Hampshire,USA

An analysis of vegetation along an altitudinal gradient on the Presidential Range, New Hampshire, USA, using the Braun–Blanquet approach followed by multivariate data analysis is presented. Twelve main plant communities have been distinguished. Floristic information is presented in twelve tables and one appendix. The relationships of the communities to complex environmental gradients are analyzed using Correspondence Analysis. Floristic composition and community structure are controlled primarily by the altitudinal gradient (temperature, precipitation), and by mesotopographic conditions (snow accumulation, exposure and cryoturbation, slope position, and soil moisture).     

Wind chill factor applied to Patagonian climatology

The wind cooling effect determines wind chill equivalent-temperatures, which may be rather different to actual temperature. In a windy region such as Patagonia, this difference may reach a magnitude and persistence to become an important bioclimatic element. This paper quantifies the wind cooling effect in Patagonia by the presentation of equivalent isotherms as an adaptation of the usual isotherm maps to the regional bioclimatic environment. It is concluded that due to seasonal variations in wind speed, the annual equivalent temperature range is smaller than the actual temperature range, thus increasing oceanic features, from a thermal viewpoint, of the Patagonian climate.«Les vents que chassent, à travers une échancrure de la Cordillère des Andes, les hautes pressions du Pacifique, s'étranglent et s'accelèrent dans un étroit couloir de cent kilomètres de front, en direction de l'Atlantique, et raclent tout sur leur passage».Antoine de Saint-Exupéry «Un sens à la vie» (1956)     

Biogeographical and bioclimatic outline of Antarctica

Abstract

This study proposes a bioclimatic characterization and a new biogeographic division for the Antarctic territories up to the province level following the criteria and models of Rivas-Martínez et al. The Antarctic Kingdom comprises the continent of Antarctica, the surrounding ice-covered Antarctic islands, and the associated cold oceanic islands and archipelagos. It has two biogeographic regions: the Antarctic Region and the Subantarctic Insular Region. The Antarctic Region includes the entire pergelid Antarctic continent and the surrounding islands and archipelagos, and is characterized by upper suprapolar hyperoceanic and oceanic or Polar pergelid bioclimates on the coasts. The region has been divided into three pr6ovinces: Maritime Antarctica, West Antarctica and East Antarctica. The Subantarctic Insular Region comprises the circumantarctic islands and archipelagos that are widespread at the southern tip of the planet’s most important oceans, mostly in the subtemperate latitudinal zone inside or not far from the Antarctic Convergence. Bioclimatically, all insular subantarctic territories (excluding the South-American Tierra de Fuego, Terra Magellanica and large islands) are characterized by thermo-suprapolar and semipolar antarctic hyperoceanic bioclimates on the coasts. Four provinces – Falklandian-South Georgian, Kerguelenian, Macquarian and Aucklandian-Campbellian – have been recognized in this region. All these units are characterized by floristic bioindicators.     

Zonobiomes, zonoecotones and azonal vegetation along the Pacific coast of North America

In this study of the Pacific coast of North America, from Baja California to Alaska, we evaluated the hypothesis that the floristic composition of azonal vegetation determines areas and distribution limits similar to those of the corresponding zonobiomes (ZB), and does so in response to the same macroclimatic changes occurring on the continental scale. To this end, 686 vascular plants of the different habitats found in 279 sites along this coastal strip were recorded. Using an objective classification system (Average Linkage Clustering) and factorial analysis, floristic data acquired in fieldwork were classified into groups, which were in turn related to regional macroclimates. Our main finding was that the azonal coastal vegetation follows a distribution model that is closely linked to the corresponding macroclimate. The four ZB of the northern Pacific coast show a flora and azonal vegetation characteristic to each zonobiome; the latitudinal limits of the azonal vegetation practically coinciding with those already established for the zonal vegetation. The Boreal and Temperate ZB show high percentages of broadly distributed elements. The floristically richest zonobiome in terms of endemic taxa is the Mediterranean zonobiome, whereas the flora of Baja California is characterized by a high number of taxa related to Neotropical flora, especially to those showing links with South America. Data on the geographical distribution and habitats of the 247 most significant coastal species are also provided.     

Relation between climate and vegetation along a Mediterranean-Temperate boundary in central Italy

The relationship between climate and vegetation was investigated along a Mediterranean-Temperate boundary in central Italy. The study area is a transition zone between the Temperate (Eurosiberian) and Mediterranean regions and has an altitudinal range of almost 1750 m. Ordination and cluster analysis were used. The results did not show any sharp boundary but a climate-vegetation mosaic ranging from upper mountain thermotype and lower hyperhumid ombrotype with Fagus sylvatica L. woodlands at higher altitudes, to meso-Mediterranean thermotype and lower subhumid ombrotype with Mediterranean maquis and Quercus ilex L. woods on the coast. Six phytoclimatic groups are distinguished and described in terms of climatic parameters, vegetation types and morphological and chorological traits. These parameters indicate a change without sharp discontinuities between groups. The Mediterranean to Temperate transition in this Tyrrhenian sector is broad and includes most of the study area.     

Vegetation formations and associations of the zonobiomes along the North American Pacific coast: from northern California to Alaska

This phytosociological study, carried out according to the Braun–Blanquet method and supported by cluster analysis, describes Walter's zonobiomes along the North American Pacific coast between the California–Oregon state border and Alaska (USA), including some interior zones of British Columbia and the Yukon Territory (Canada). Twenty two floristic associations are identified and each is characterized by a unique floristic combination, a distinctive geographical range and particular bioclimatic or edaphic conditions.     

Quantitative palaeoclimatic inference based on terrestrial mammal faunas

Aim The main goal of this paper is to propose a new tool, in the form of Quantitative Bioclimatic Models (QnBMs), for reconstructing past climates based on fossil mammal associations. As a case study, European climatic conditions during the basal early Pleistocene will be inferred using QnBMs. Location The study uses faunas throughout the world to develop a quantitative bioclimatic model, which is then applied to Quaternary faunas from Eurasia. Methods The models were constructed by applying multivariate linear regression to modern mammal faunas and climates from all over the world. The models were validated with a second group of modern faunas, which includes several from transitional zones between different climates (ecotones). To test the reliability of the method when applied to fossil associations, the results obtained for the Pleistocene have been compared with those obtained from palynology. Results Validation of the models shows that as many as 11 climatic factors can be inferred with high reliability using the regression models developed in this work. Comparisons of results in the late Pleistocene–Holocene of Barová (Czech Republic) between a palynological study and the quantitative bioclimatic analysis show a high degree of similarity. The results for the early Pleistocene show colder and drier climatic conditions for Europe than today. Main conclusions The application of the quantitative bioclimatic models to present day as well as Quaternary mammal faunas proves to be a useful tool for palaeoclimatic reconstruction during the Quaternary and probably most of the Neogene. Transfer functions are presented for a complete set of climatic factors, allowing a precise estimation of the climate in a locality from its mammal fauna.     

Actual evapotranspiration and deficit: biologically meaningful correlates of vegetation distribution across spatial scales

Correlative approaches to understanding the climatic controls of vegetation distribution have exhibited at least two important weaknesses: they have been conceptually divorced across spatial scales, and their climatic parameters have not necessarily represented aspects of climate of broad physiological importance to plants. Using examples from the literature and from the Sierra Nevada of California, I argue that two water balance parameters—actual evapotranspiration (AET) and deficit (D)—are biologically meaningful, are well correlated with the distribution of vegetation types, and exhibit these qualities over several orders of magnitude of spatial scale (continental to local). I reach four additional conclusions. (1) Some pairs of climatic parameters presently in use are functionally similar to AET and D; however, AET and D may be easier to interpret biologically. (2) Several well-known climatic parameters are biologically less meaningful or less important than AET and D, and consequently are poorer correlates of the distribution of vegetation types. Of particular interest, AET is a much better correlate of the distributions of coniferous and deciduous forests than minimum temperature. (3) The effects of evaporative demand and water availability on a site's water balance are intrinsically different. For example, the 'dry' experienced by plants on sunward slopes (high evaporative demand) is not comparable to the 'dry' experienced by plants on soils with low water-holding capacities (low water availability), and these differences are reflected in vegetation patterns. (4) Many traditional topographic moisture scalars—those that additively combine measures related to evaporative demand and water availability—are not necessarily meaningful for describing site conditions as sensed by plants; the same holds for measured soil moisture. However, using AET and D in place of moisture scalars and measured soil moisture can solve these problems.     

The bioclimatic model: a method of palaeoclimatic qualitative inference based on mammal associations

Aim The bioclimatic model is a new method for palaeoclimatic reconstruction built on the assumption of a significant correlation between climate and mammal community composition. The goal of this approach is to infer past climatic conditions using mammal fossil associations as source data. Location The study used mammal faunas from all over the world to develop the bioclimatic model. As an example of the potential of the model, we have applied it to Quaternary faunas from Eurasia. Methods The proposed model was constructed by applying multivariate discriminant analysis to modern mammal faunas and climates from throughout the world. The model was validated with a different set of modern faunas than those used in the discriminant analysis, including some from transitional zones between different climates (ecotones). To test the reliability of the method in the Pleistocene, the results have been compared to those obtained with data from other disciplines, such as palaeobotany. Results The results obtained in the validation of the model show that more than 90% of the localities have been classified correctly. Comparisons of results in the late Pleistocene‐Holocene of Barová between a palaeobotanical study and the bioclimatic analysis show the latter to be highly accurate. The results for early Pleistocene faunas show somewhat drier and more open climatic conditions for Europe than the present day, with larger areas of steppe environments. Main Conclusions The bioclimatic model could be used to infer climatic conditions from mammal faunas. The results presented in this work provide a preliminary example of the potential that bioclimatic analysis has as a tool for palaeoclimatic inference. Finally, this method offers the opportunity to standardize data coming from vertebrate palaeontology for use in the construction and evaluation of climatic models.     

Potential impacts of climate change on habitat suitability of Fagus sylvatica L. forests in spain

Abstract

Fagus sylvatica forests are considered to be of Community interest according to Directive 92/43/EEC. Climate change predictions for Spain point to a warming scenario, coupled with decreasing rainfall, which may have an impact on their future distribution particularly at the extremes of its distribution area. Species distribution models incorporating bioclimatic, topographic and phytogeographic variables were used as predictors to assess their habitat suitability under current conditions and a climate change projection. Ten single models were generated and an ensemble-forecasting model was subsequently built by computing a consensus of single-model projections. The results revealed that ombrothermic indices are the main factors controlling the distribution of Spanish beech forests. They are highly vulnerable to climate change and could suffer a decline in their habitat suitability if climate trends observed are maintained in the future. The least favoured areas for them will be located close to the limit between the Temperate and Mediterranean climates, where they could suffer a loss of habitat suitability. Conversely, suitable new areas could be found mainly in western areas of the Cantabrian Range and in the Central Pyrenees.