S. del Río

Recent trends in mean maximum and minimum air temperatures over Spain (1961–2006)

This study analyzes the mean maximum and minimum temperature trends on a monthly, seasonal, and annual timescale by applying various statistical tools to data from 476 Spanish weather stations during the period between 1961 and 2006. The magnitude of the trends was derived from the slopes of the regression lines using the least squares method, and the nonparametric Mann–Kendall test was used to determine the statistical significance of the trends. Temperature significantly increased in over 60% of the country in March, June, spring, and summer in the case of maximum temperatures and in March, May, June, August, spring, and summer for minimum temperatures. At the annual resolution, temperatures significantly increased in over 90% of Spain with a rise of around 0.3°C/decade. The maximum temperature increased at a higher rate than the minimum temperature from midsummer to early winter as well as in winter, spring, and summer and also on an annual basis.

Potential areas of deciduous forests in Spain (Castile and Leon) according to future climate change

Abstract Areas that currently may be potentially occupied by deciduous forests represent approximately 5.5% of the Castile and Leon area. These forests include plant communities mainly dominated by Fagus sylvatica L., Quercus petraea (Mattuschka) Libl. and Betula pubescens Ehrh. subsp. celtiberica (Roth. & Vasc.) Rivas-Martínez. Taking into account the observed trends in annual mean temperature and precipitation in this region over a 37 years period (1961 – 1997), three climatic variation scenarios (for 2025, 2050 and 2075) have been proposed to determine the potential consequences of climatic change on the distribution patterns of the most representative deciduous forests. According to these scenarios, a more oceanic climate can be expected, leading to an increase in territories having a temperate climate. In this situation, deciduous forests could increase their distribution limits, thus replacing some semi-deciduous and evergreen ones. The paper also emphasizes the relevance of using bioclimatic models to anticipate possible changes in the natural vegetation of a territory. Thus, better knowledge of the seasonal distribution of temperature and rainfall under a climate change is necessary for forecasting effects on the forest distribution of a given region.

Incorporating bioclimatic and biogeographic data in the construction of species distribution models in order to prioritize searches for new populations of threatened flora

The aim of this study was to analyse the usefulness of incorporating bioclimatic and biogeographic data into digital species prediction and modelling tools in order to identify potential habitats of rare or endangered flora taxa. Species distribution models (SDMs) were obtained using the Maximum entropy algorithm. Habitat suitability maps were based on sites of known occurrence of studied species. The study showed that highly reliable habitat prediction models can be obtained through the inclusion of bioclimatic and biogeographic maps when modelling these species. The resultant SDMs are able to fit the search area more closely to the characteristics of the species, excluding the percentage of highly suitable areas that are located far from the known distribution of the taxon, where the probability of finding the plant is low. Therefore, it is possible to overcome one of the most commonly encountered problems in the construction of rare or threatened flora taxa SDMs, derived from the low number of initial citations. The resulting SDMs and the vegetation map enable prioritization of the search for new populations and optimization of the economic and human resources used in the collection of field data.

Contribution to the phytosociological survey of the primary forests in the NE of Rio Grande do Sul (Brazil)

Abstract We present the results of a phytosociological survey of the primary forests of different areas in the NE of Rio Grande do Sul (Brazil). The study combines the Braun‐Blanquet’s methodology of collecting phytosociological data with a technique of numerical classification (Average Linkage Clustering based on Euclidean distance). Five associations, five sub‐associations, three alliances, two orders and one phytosociological class are proposed in this paper on the basis of the cluster analysis of 59 phytosociological relevés, and of floristic, biogeographical, bioclimatic, edaphic, and physiognomic data from previous phytosociological studies of Brazil’s forests.

A phytosociological survey of some serpentine plant communities in the Dominican Republic

This paper presents a floristic and vegetation study of the serpentinised territories of the Dominican Republic, corresponding to the Yamasá and Prieta mountains, Dajabón, Puerto Plata and Gaspar Henández. These sites are very important at a local level as they act as speciation centres and have a specific ultramafic flora with a high endemicity rate. The floristic analysis revealed the existence of 219 species, of which 54 (24.7%) are endemic. Twenty-one plots of vegetation distributed in five areas dominated by serpentines have been analysed in this study. The phytosociological approach is based on the Braun-Blanquet method. The study was combined with statistical techniques such as multivariate analyses. The results revealed three different kinds of forests, one dominated by the endemic Bignoniaceae, Tabebuia berterii (CC.) Britton, which is peculiar to the subhumid–humid environments of the Caribbean-Cibensean territory. The second type of forest is dominated by the serpentinophyte Polygonaceae, Leptogonum buchii Urb. which thrives in the humid ombrotype of the north territory. Finally, the third one adopts the form of the pine forest of Dajabón, dominated by Pinus occidentalis Sw. Four associations and three alliances are proposed as new syntaxa based on statistical and phytosociological analyses.

Temporihygrophilous Quercus broteroi forests in southern Portugal: Analysis and conservation

Abstract This article deals with a phytosociological survey of marcescent Portuguese oak (Quercus broteroi) forests in southern Portugal, and presents the results of an analysis of 56 relevés, combining Braun–Blanquets methodology with hierarchical cluster analysis (Wards Hierarchical Clustering, based on Bray–Curtis distance). From these results, a new temporihygrophilous Portuguese oak forest association is described. Largely thermomediterranean, upper dry to subhumid, Ulici welwitschiani–Quercetum broteroi occurs on limestone soils within the Coastal Lusitan-Andalusian Province. Its high conservation value – mainly due to its rarity and floristic structure – supports this forests integration in Habitat 9240 (Annex B-I from Council Directive 92/43/EEC) in order to ensure its preservation. Based on the results, new biogeographic borders for the Ribatagan-Sadensean Sector are proposed.

Syntaxonomic update on the relict groves of Mirbeck's oak (Quercus canariensis Willd. and Q. marianica C. Vicioso) in southern Iberia

As relict traces of the Tertiary period, Quercus canariensis Willd. and the forests it forms comprise one of the most interesting woodlands, which prevails in southern Iberia with very particular edaphoclimatic envelopes. Combining phytosociological methodology with hierarchical cluster analyses, we aim to update the syntaxonomic scheme of the forests related to this species and the complex matrixes it forms with the hybrid species Quercus marianica C. Vicioso. We propose one new association from Portugal, in a total of four types of Mirbecks oak woodlands, in Southern Iberia. We conclude the necessity to maintain high standards on taxonomic and geobotanical surveys, with major biogeographic knowledge; it is indissociable from an accurate analysis and comprehension on the functional ecology and structure of these woodlands, regarding its dynamics. Therefore, their high conservation value, related to its relict status, supports the integration of these forests in Habitat 9240 (Annex B-I from Council Directive 92/43/EEC) in order to ensure its preservation.