A numerical phytoclimatic classification of China

The relationship is examined between vegetation and climate using climatic variables collected from 644 meteorological stations located throughout China. Multivariate methods are applied directly to the raw climatic data in order to define climatic clusters and to examine the relationship between the clusters and vegetation types. This approach is based on the concept of multidimensional climatic space defined by the combination of climatic variables. Phytoclimatic classes are defined on the basis of the distribution of vegetation types in climatic clusters and a new phytoclimatic classification of China is proposed. Patterns of climatic changes between neighbouring phytoclimatic classes are described. Two indexes of the influence of climate on vegetation are proposed based on discriminant analysis.     

Environmental filtering increases in intensity at both ends of climatic gradients,though driven by different factors,across woody vegetation types of the southwest USA

Species distributions are theorized to be more intensively constrained by abiotic factors in severe than in benign environments. A similar concept can be applied to assemblages of species: environmental filtering is expected to increase in intensity in colder and drier environments. To assess the filtering effects of climate on vegetation at a regional scale, climate niche values were estimated for 338 woody species across 93 vegetation types from arid sub‐tropical to alpine ecosystems of the southwest USA. The standardized range and spacing of climatic niche values in each vegetation type – used as estimates of the intensity of climatic and micro‐environmental filtering, respectively – were correlated with the mean niche values of those vegetation types – used as surrogates for climatic gradients – in order to assess how filtering of vegetation composition varies along broad climatic gradients. The range of climatic niche values was narrower than expected in most vegetation types, indicating significant climatic filtering, with frost having the strongest average effect. Niche spacing differed little from null expectations. Variation in the intensity of climatic filtering along gradients of the same climate variable was primarily asymmetrical, and provided support for the hypothesis that abiotic filtering is most intense in cold and growing season dry environments. However, filtering patterns of at least one climatic factor along gradients of other climatic factors ran counter to the trend of increasing filter intensity in cold or dry environments. In other words, climatic factors exhibited interactive effects on vegetation filtering, often in antagonistic ways. The majority of these interactions were compatible with interspecific niche relationships that correspond with anatomical and physiological tradeoffs among drought, frost and heat tolerances. Filtering patterns and interspecific tradeoffs are likely to vary across taxa and biomes, and application of the methods presented here could help to explain such variation.     

Determinants of bird species richness: role of climate and vegetation structure at a regional scale

We examined the respective roles of climate and vegetation structure on geographical variation in bird species richness. The Province of Buenos Aires (central-eastern Argentina) was divided into 146 squares of 50 km on a side. For each square we evaluated the number of bird species, the value of thirteen climatic variables, and the value of a vegetation strata index. The climatic matrix was analyzed by Principal Component Analysis (PCA), and the first factors resulting from PCA were considered as multifactorial climatic gradients. Simple and Partial Correlation Analysis among bird species richness, vegetation strata, and the first two factors derived from PCA (65% of total variation) indicated that bird richness distribution was determined by the availability of vegetation strata, associated with different vegetation types that, at the same time, were influenced by the climatic conditions summarized in the first climatic factor (a gradient of precipitation, relative humidity, annual termical amplitude, and frost occurrence). This relationships reflect the complexity of factors that can act directly as well as indirectly on the geographical patterns in species richness. Also, we evaluated the importance of study scale comparing our results with previous studies at macrogeographic and local scales, found out that the vegetation structure was the principal determinant of bird species richness at this three geographical scales.     

Trajectory analysis of Chinese vegetation types in a multidimensional climatic space

Abstract. The concept of trajectory of a vegetation type is used as a tool to study the position of vegetation types in a multidimensional climatic space. This space was obtained by Principal Component Analysis based on climatic data - based on monthly means. The positions of the main vegetation types distinguished in China were plotted in the climatic space and trajectory lengths and shapes of the types were compared. Three main groups were found, which correspond to: (1) cold and temperate, (2) alpine and mountain, and (3) subtropical and tropical conditions. Within each main category sub-categories were distinguished on the basis of trajectory length and direction. In total, seven trajectory shapes were defined. Based on the correlation between climatic variables and PCA-axes temperature is suggested to be the overriding factor in determining the trajectory shape. But, trajectories can also be affected by the combination of other climatic variables.     

Global vegetation productivity response to climatic oscillations during the satellite era

Climate control on global vegetation productivity patterns has intensified in response to recent global warming. Yet, the contributions of the leading internal climatic variations to global vegetation productivity are poorly understood. Here, we use 30 years of global satellite observations to study climatic variations controls on continental and global vegetation productivity patterns. El Niño‐Southern Oscillation (ENSO) phases (La Niña, neutral, and El Niño years) appear to be a weaker control on global‐scale vegetation productivity than previously thought, although continental‐scale responses are substantial. There is also clear evidence that other non‐ENSO climatic variations have a strong control on spatial patterns of vegetation productivity mainly through their influence on temperature. Among the eight leading internal climatic variations, the East Atlantic/West Russia Pattern extensively controls the ensuing year vegetation productivity of the most productive tropical and temperate forest ecosystems of the Earth's vegetated surface through directionally consistent influence on vegetation greenness. The Community Climate System Model (CCSM4) simulations do not capture the observed patterns of vegetation productivity responses to internal climatic variations. Our analyses show the ubiquitous control of climatic variations on vegetation productivity and can further guide CCSM and other Earth system models developments to represent vegetation response patterns to unforced variability. Several winter time internal climatic variation indices show strong potentials on predicting growing season vegetation productivity two to six seasons ahead which enables national governments and farmers forecast crop yield to ensure supplies of affordable food, famine early warning, and plan management options to minimize yield losses ahead of time.     

全球气候变暖胁迫下的雅鲁藏布江流域植被覆盖度变化驱动机制探讨

为了解雅鲁藏布江流域内植被变化对气候变化响应的时空差异性,引入重心模型,分析和探讨了2002-2014年雅鲁藏布江流域植被的变化特点与气候因子的相关性。结果表明,植被的NDVI(归一化植被指数,Normalized difference vegetation index)重心与降水重心年际迁移方向具有正相关性。雅鲁藏布江流域的月植被NDVI受前0-1月降水影响最大,而不同季节植被的NDVI对降水影响表现出一定的滞后性,其中春季和冬季的植被NDVI均与前一季的降水呈现正相关性。该流域中乔木、灌木对降水反应的滞后性比草本植物要大;生长季的温度变化与植被的生长具有相关性。植被NDVI与月均温的正相关性达到最大的时间段差异较大。因此,植被NDVI和气候因子间的时空异质性研究对于雅鲁藏布江流域的生态环境保护具有重要意义。     

Colombian dry moist forest transitions in the Llanos Orientales—A comparison of model and pollen-based biome reconstructions

Colombian vegetation, at the ecological level of the biome, is reconstructed at six sites using pollen data assigned a priori to plant functional types and biomes. The chosen sites incorporate four savanna sites (Laguna Sardinas, Laguna Angel, El Piñal and Laguna Carimagua), a site on the transition between savanna and Amazon rainforest (Loma Linda) and a site within the Amazon rainforest (Pantano de Monica). The areal extent of tropical moist forest, tropical dry forest and steppe have been subject to significant change: differential responses of the vegetation to climatic shifts are related to changes in plant available moisture, duration of dry season and edaphic controls on the vegetation. The record from El Piñal shows that the present-day savanna vegetation, dominated by steppe (Poaceae) with little occurrence of woody savanna taxa (e.g. Curatella, Byrsonima), was present since the last glacial period of the northern hemisphere. Unfortunately, El Piñal is located on an edaphic savanna and is not particularly responsive to registering change. Most records cover the early Holocene; one site records the El Abra stadial (Younger Dryas equivalent), when forest expansion reflects more humid climatic conditions and higher plant available moisture. During the early and middle Holocene, the maximum expansion of steppe and tropical dry forest occurred, indicating that dry climatic conditions continued to around 4000 ¹⁴C BP. The following period, from shortly before 4000 ¹⁴C BP, is characterised by an increase in forest and gallery forests, reflecting a wetter period probably with a shorter annual dry season. Anthropogenic influence on the vegetation is recorded by all the records over the last millennial, particularly characterised by a reduction in forest cover and high amplitude changes in vegetation.Biome transitions from one type to another, and the environmental controls on this shift, are investigated by applying a vegetation model (BIOME-3). The model uses climatic data from six meteorological stations that, encompass a range of environments within lowland Colombia, which are similar to the pollen data. The signals of vegetation change can be translated to the main environmental controls of temperature and moisture to indicate the degree of change needed in these parameters to record the vegetation change depicted by the pollen data. Moisture balance is the dominant control on driving vegetation change whether under seasonal or annual control. The combined reconstruction from pollen data and model output of biome-scale vegetation dynamics for lowland Colombia allows an understanding of the environmental controls to be developed.     

Zonal and azonal vegetation revisited: How is wetland vegetation distributed across different zonobiomes

In ‘zonal’ vegetation, climatic factors are the main influence on growth and performance and the climate determines the vegetation type completely, which makes this vegetation dominant in the landscape. If vegetation is ‘azonal’ however, local stresses are assumed to have an overwhelming influence on plant performance and climatic influences will be minimal; typically, this vegetation occurs only in small patches in the landscape. In this study I ask whether wetland plant communities, as they are described for South Africa, are evenly distributed among different terrestrial vegetation types, to test whether they are zonal or azonal. Three contingency tables were construed based on the counts of wetland vegetation records, defined on three hierarchical levels (Main Clusters, Community Groups and Community) and their occurrence in the country (at the level of Biome, Bioregion and terrestrial vegetation type). An ‘azonality index’ was calculated as the sum of all Chi‐square values for each wetland vegetation type divided by the total number of records. The overall correlation between hydroperiod and the azonality index was very weak. At the finest level, terrestrial vegetation types were clustered on the basis of having similar combinations of wetland community types. Eighteen different ‘wetland ecoregions’ have been defined, on the basis of wetland vegetation types occurring within them. Instead of regarding wetland vegetation as azonal, it should rather be regarded as ‘intrazonal’, meaning that climate does have an impact but many vegetation types are widespread across climatic regions. The reason why community types in wetlands are widespread is due to the monodominance of a single widespread, often clonal, species. The different wetland ecoregions do not correspond to terrestrial biomes, so it is expected that wetland vegetation responds differently to climate than terrestrial vegetation.     

土地利用约束下中国东部南北样带生产力和植被分布对全球变化的响应

对现有的区域植被动态模拟模型进行了改进,使之包含了土地利用分布格局对植被和生态系统相关过程的影响。改进后的模型被用地研究中国东部南北样带(NSTEC)植被和净第一性生产力对未来气候变化的响应。模拟结果显示土地利用格局对未来气候条件下植被分布的变迁和生产力形成过程有非常显著的影响。与没有土地利用约束的情形相比较,土地利用作为限制条件缓减了植被类型之间的竞争,从而减少了模拟的样带区域内常绿阔叶林,但增加了模拟灌木和草地的分布。土地利用约束使得模拟得到的当前条件下的净第一性生产力更为接近实际情况,且未来气候条件下的生产力改变量更为可信。对未来CO2倍增条件下7个大气环流模型预测的气候情景的模拟结果表明：落叶阔叶林将显著增加,但针叶林、灌木和草原的分布将下降。未来气候条件下NSTEC样带的净第一性生产力总量将增加。预测样带北部的净第一性生产力的变化范围大于样带南部。温度变化比降水变化对样带的生产力具有更强的控制。     

土地利用约束下中国东部南北样带生产力和植被分布对全球变化的响应

对现有的区域植被动态模拟模型进行了改进,使之包含了土地利用分布格局对植被和生态系统相关过程的影响.改进后的模型被用于研究中国东部南北样带(NSTEC)植被和净第一性生产力对未来气候变化的响应.模拟结果显示土地利用格局对未来气候条件下植被分布的变迁和生产力形成过程有非常显著的影响.与没有土地利用约束的情形相比较,土地利用作为限制条件缓减了植被类型之间的竞争,从而减少了模拟的样带区域内常绿阔叶林,但增加了模拟灌木和草地的分布.土地利用约束使得模拟得到的当前条件下的净第一性生产力更为接近实际情况,且未来气候条件下的生产力改变量更为可信.对未来CO2倍增条件下7个大气环流模型预测的气候情景的模拟结果表明:落叶阔叶林将显著增加,但针叶林、灌木和草原的分布将下降.未来气候条件下NSTEC样带的净第一性生产力总量将增加.预测样带北部的净第一性生产力的变化范围大于样带南部.温度变化比降水变化对样带的生产力具有更强的控制.     

Climate and vegetation at the Eurosiberian-Mediterranean boundary in the Iberian Peninsula

Abstract. The Northern Iberian Peninsula is dominated by various types of vegetation from deciduous oak and ash to evergreen oak woodlands. A recent vegetation map of Spain portrays vegetation series which are characterized in terms of their phytogeographic region or bioclimatic (altitudinal) belt. The aim of this paper is to determine whether the areas comprised by both phytogeographic regions (Eurosiberian and Mediterranean) in the study area, as established from the phytogeographic characterization of the vegetation, can be discriminated by climatic variables using multivariate methods, and to compare these with other conventional approaches. In addition, bioclimatic (altitudinal) belts and the main vegetation types were tested for discrimination by climatic variables. Conventional climatic criteria as well as discriminant and principal component analysis were applied to climatic data from 205 meteorological stations for which vegetation information had been taken from the vegetation map. Conventional criteria are good predictors of the phytogeographic division (Mediterranean and Eurosiberian regions) in the study area. Results were improved by multiple discriminant analysis based on climatic data of the dry period of the year (June to September). Both regions in the study area can be predicted with over 95 % accuracy. Using the same multivariate procedure and temperature data the bioclimatic (altitudinal) belts of the study area can be predicted with over 90 % accuracy. The main vegetation groups of the study area can also be predicted with over 80 % accuracy. Ordination analysis supported the results of the discriminant analysis. Empirical models have been generated to predict the phytogeographic- and belt character of any station in the area. The significance of the various periods of the year for discriminating regions and belts is evaluated. The responsiveness to climatic events during the year may be region specific. This study confirms the strong relationship between climate and vegetation in the Northern Iberian Peninsula, particularly regarding the Eurosiberian-Mediterranean boundary.     

Climate and coastal dune vegetation: disturbance, recovery, and succession

The sand dune habitats found on barrier islands and other coastal areas support a dynamic plant community while protecting areas further inland from waves and wind. Foredune, interdune, and backdune habitats common to most coastal dunes have very different vegetation, likely because of the interplay among plant succession, exposure, disturbance, and resource availability. However, surprisingly few long-term data are available describing dune vegetation patterns. A nine-year census of 294 plots on St. George Island, Florida suggests that the major climatic drivers of vegetation patterns vary with habitat. Community structure is correlated with the elevation, soil moisture, and percent soil ash of each 1 m² plot. Major storms reduce species richness in all three habitats. Principle coordinate analysis suggests that changes in the plant communities through time are caused by climatic events: changes in foredune vegetation are correlated with temperature and summer precipitation, interdune vegetation with storm surge, and backdune vegetation with precipitation and storm surge. We suggest that the plant communities in foredune, interdune, and backdune habitats tend to undergo succession toward particular compositions of species, with climatic disturbances pushing the communities away from these more deterministic trajectories.     

Extreme climatic events and vegetation: the role of stabilizing processes

Current climatic trends involve both increasing temperatures and climatic variability, with extreme events becoming more frequent. Increasing concern on extreme climatic events has triggered research on vegetation shifts. However, evidences of vegetation shifts resulting from these events are still relatively rare. Empirical evidence supports the existence of stabilizing processes minimizing and counteracting the effects of these events, reinforcing community resilience. We propose a demographic framework to understand this inertia to change based on the balance between adult mortality induced by the event and enhanced recruitment or adult survival after the event. The stabilizing processes potentially contributing to this compensation include attenuation of the adult mortality caused by the event, due to site quality variability, to tolerance, phenotypic variability, and plasticity at population level, and to facilitative interactions. Mortality compensation may also occur by increasing future survival due to beneficial effect on growth and survival of the new conditions derived from global warming and increased climatic variability, to lowered competition resulting from reduced density in affected stands, or to antagonistic release when pathogens or predators are vulnerable to the event or the ongoing climatic conditions. Finally, mortality compensation may appear by enhanced recruitment due to release of competition with established vegetation, for instance as a consequence of gap openings after event‐caused mortality, or to the new conditions, which may be more favorable for seedling establishment, or to enhanced mutualistic interactions (pollination, dispersal). There are important challenges imposed by the need of long‐term studies, but a research agenda focused on potentially stabilizing processes is well suited to understand the variety of responses, including lack of sudden changes and community inertia that are frequently observed in vegetation under extreme events. This understanding is crucial for the establishment of sound management strategies and actions addressed to improve ecosystem resilience under climate change scenarios.     

Is vegetation in equilibrium with climate? How to interpret late-Quaternary pollen data

Current methods for estimating past climatic patterns from pollen data require that the vegetation be in dynamic equilibrium with the climate. Because climate varies continuously on all time scales, judgement about equilibrium conditions must be made separately for each frequency band (i.e. time scale) of climatic change. For equilibrium conditions to exist between vegetation and climatic changes at a particular time scale, the climatic response time of the vegetation must be small compared to the time scale of climatic variation to which it is responding. The time required for vegetation to respond completely to climatic forcing at a time scale of 10⁴ yr is still unknown, but records of the vegetational response to climatic events of 500-to 1000-yr duration provide evidence for relatively short response times. Independent estimates for the possible patterns and timing of late-Quaternary climate changes suggest that much of the vegetational evidence previously interpreted as resulting from disequilibrium conditions can instead be interpreted as resulting from the individualistic response of plant taxa to the different regional patterns of temperature and precipitation change. The differences among taxa in their response to climate can lead a) to rates and direction of plant-population movements that differ among taxa and b) to fossil assemblages that differ from any modern assemblage. An example of late-Holocene vegetational change in southern Quebec illustrates how separate changes in summer and winter climates may explain the simultaneous expansion of spruce (Picea) populations southward and beech (Fagus) populations northward.     

Vegetation dynamics and responses to recent climate change in Xinjiang using leaf area index as an indicator

There is a strong signal showing that the climate in Xinjiang, China has changed from warm-dry to warm-wet since the early 1980s, leading to an increase in vegetation cover. Based on a regression analysis and Hurst index method, this study investigated the spatial–temporal characteristics and interrelationships of the vegetation dynamics and climate variability in Xinjiang Province using the leaf area index (LAI) and a gridded meteorological dataset for the period 1982–2012. Further analysis focused on the discrimination between climatic change and human-induced effects on the vegetation dynamics, and several conclusions were drawn. (1) Vegetation dynamics differ in mountain and plains regions, with a significant increasing trend of vegetation cover in oases and decreasing trend of vegetation growth in the Tienshan and Altay Mountain. The Hurst exponent results indicated that the vegetation dynamic trend was consistent, with a sustainable area percentage of 51.18%, unsustainable area percentage of 4.04%, and stable and non-vegetated area ratio of 44.78%. (2) The warm-dry to warm-wet climatic pattern in Xinjiang Province since the 1980s mainly appeared in the western part of the Tienshan region and North Xinjiang. Temperatures increased in all seasons over the majority of Xinjiang, and precipitation showed a significant increasing trend in the mountainous regions in spring, summer and autumn, whereas the rate of precipitation change was higher in the plains region in winter compared with that in other seasons. (3) A correlation occurs between the climate variables (precipitation and temperature) and mean LAI, and this correlation varies at the seasonal and regional scales, with coniferous forest, meadow and grassland more correlated with precipitation in spring and summer and not correlated with temperature, which indicated that precipitation was the dominant factor affecting the growth of mountain vegetation. The mean LAI of vegetation in the plains exhibited significant correlation with precipitation in winter and temperature in spring and summer. (4) A residual analysis showed a human-induced change that was superimposed on the climate trend and exhibited two effects: vegetation regeneration in oases throughout Xinjiang and desertification in the meadow located in the mountainous area of the western Tienshan Mountains and Altay Mountains. (5) Grassland is the most sensitive vegetation type to short-term climatic fluctuations and is the land-use type that has been most severely degraded by human activity; thus, local governments should take full advantage of this climatic warm-wet shift and focus on protecting vegetation to improve this fragile arid environment.     

Diversity of Rich Fen Vegetation and Related Plant Specialists in Mountain Refugia of the Iberian Peninsula

In temperate mountains, fens have been reported as relict habitats subject to geographical fragmentation and broad climatic gradients, but few studies have analyzed the influence of these factors on plant diversity. Here we investigate the effect of isolation on the vegetation diversity of rich fens (Caricion davallianae) in the mountains of the Iberian Peninsula, the distribution limit of these habitats in south-western Europe. We used plot-based vegetation data from the Pyrenees and the Cantabrian mountain range to evaluate their regional species-pool, occurrence of specialists, beta-diversity and the effect of geo-climatic variables on their species-richness and species-composition. We found a lower ratio of rare specialists in the Pyrenees than in the Cantabrian range, but similar estimates in the species pools, total species-richness per plot and beta-diversity. The isolation of the two mountain regions resulted in different species assemblages best predicted by summer precipitation and bedrock types, showing region-based differences in the response of vegetation and plant specialists to the environment. The tighter correlation between local climate and diversity estimates in the Cantabrian range suggests relict character of rich fens in that region, where climatic conditions have restricted local distribution of formerly more widely distributed specialists. Although there is no relevant evidence of vegetation impoverishment in that region, historical isolation has probably resulted in the existence of fragmentary plant communities. We conclude that fen vegetation may experience long-time persistence in climatically sub-optimal mountain refugia, but related plant specialists may be sensitive to climatic changes and subject to the extinction of local populations.     

Unusual forest growth decline in boreal North America covaries with the retreat of Arctic sea ice

The 20th century was a pivotal period at high northern latitudes as it marked the onset of rapid climatic warming brought on by major anthropogenic changes in global atmospheric composition. In parallel, Arctic sea ice extent has been decreasing over the period of available satellite data records. Here, we document how these changes influenced vegetation productivity in adjacent eastern boreal North America. To do this, we used normalized difference vegetation index (NDVI) data, model simulations of net primary productivity (NPP) and tree‐ring width measurements covering the last 300 years. Climatic and proxy‐climatic data sets were used to explore the relationships between vegetation productivity and Arctic sea ice concentration and extent, and temperatures. Results indicate that an unusually large number of black spruce (Picea mariana) trees entered into a period of growth decline during the late‐20th century (62% of sampled trees; n = 724 cross sections of age >70 years). This finding is coherent with evidence encoded in NDVI and simulated NPP data. Analyses of climatic and vegetation productivity relationships indicate that the influence of recent climatic changes in the studied forests has been via the enhanced moisture stress (i.e. greater water demands) and autotrophic respiration amplified by the declining sea ice concentration in Hudson Bay and Hudson Strait. The recent decline strongly contrasts with other growth reduction events that occurred during the 19th century, which were associated with cooling and high sea ice severity. The recent decline of vegetation productivity is the first one to occur under circumstances related to excess heat in a 300‐year period, and further culminates with an intensifying wildfire regime in the region. Our results concur with observations from other forest ecosystems about intensifying temperature‐driven drought stress and tree mortality with ongoing climatic changes.     

Quantifying the biologically possible range of steady-state soil and surface climates with climate model simulations

The terrestrial biosphere shapes the exchange fluxes of energy and mass at the land surface. The diversity of plant form and functioning can potentially result in a wide variety of possible climatic conditions at the land surface and in the soil, which in turn feed back to more or less suitable conditions for terrestrial productivity. Here, I use sensitivity simulations to vegetation form and functioning with a global climate model to quantify this possible range of steady-states (“PROSS”) of the surface energy-and mass balances. The surface energy-and water balances over land are associated with substantial sensitivity to vegetation parameters, with precipitation varying by more than a factor of 2, and evapotranspiration by a factor of 5. This range in biologically possible climatic conditions is associated with drastically different levels of vegetation productivity. Optimum conditions for maximum productivity are close to the simulated climate of present-day conditions. These results suggest the conclusions that (a) climate does not determine vegetation form and function, but merely constrains it, and (b) the emergent climatic conditions at the land surface seem to be close to optimal for the functioning of the terrestrial biosphere.     

The use of climatic parameters and indices in vegetation distribution. A case study in the Spanish Sistema Central

In this study, over 100 phytoclimatic indices and other climatic parameters were calculated using the climatic data from 260 meteorological stations in a Mediterranean territory located in the centre of the Iberian Peninsula. The nature of these indices was very different; some of them expressed general climatic features (e.g. continentality), while others were formulated for different Mediterranean territories and included particular limits of those indices that expressed differences in vegetation distribution. We wanted to know whether all of these indices were able to explain changes in vegetation on a spatial scale, and whether their boundaries worked similarly to the original territory. As they were so numerous, we investigated whether any of them were redundant. To relate vegetation to climate parameters we preferred to use its hierarchical nature, in discrete units (characterized by one or more dominant or co-dominant species), although it is known to vary continuously. These units give clearer results in this kind of phytoclimatic study. We have therefore used the main communities that represent natural potential vegetation. Multivariate and estimative analyses were used as statistical methods. The classification showed different levels of correlation among climatic parameters, but all of them were over 0.5. One hundred and eleven parameters were grouped into five larger groups: temperature (T), annual pluviothermic indices (PTY), summer pluviothermic indices (SPT), winter potential evapotranspiration (WPET) and thermal continentality indices (K). The remaining parameters showed low correlations with these five groups; some of them revealed obvious spatial changes in vegetation, such as summer hydric parameters that were zero in most vegetation types but not in high mountain vegetation. Others showed no clear results. For example, the Kerner index, an index of thermal continentality, showed lower values than expected for certain particular types of vegetation. Parameters relating to the water balance turned out to be very discriminative for separating vegetation types according to the season or the month when water begins to be scarce. Thus, water availability in soils is a limiting factor for the development of vegetation in spring or autumn as well as in summer. As expected, precipitation and temperature discriminated the altitudinal levels of vegetation. Finally, these index limits only worked in the territories where they were formulated, or in nearby areas.