Abstract

HERNANDEZ CERDA, María Engracia; ORDONEZ DIAZ, María de Jesús  and  GIMENEZ DE AZCARATE, Joaquín. Comparative Analysis of Two Bioclimatic Classification Systems Applied in Mexico. Invest. Geog [online]. 2018, n.95. ISSN 2448-7279.  https://doi.org/10.14350/rig.57451.

The characteristics of the different types of climate result from the functioning of the climate system and reflect the influence of the various components that collectively affect it. The study of climate behavior, distribution and evolution analyzes various meteorological elements (temperature, precipitation, wind, atmospheric pressure, humidity, etc.), at different spatial and temporal ranges that can be considered either individually or in combination.

Bioclimatic studies are structured from the establishment of relationships between climatology and the distribution of plants.

This paper reviews and applies two climate classification proposals related to the vegetation to Mexico: a) the Modified System (SM), based on Köppen’s climate classification, selected because it is widely known, easily applied, based on the implicit premise that natural vegetation is an indicator of climate, and for considering that some of its categories are supported on the climatic boundaries of certain plant formations. It was modified to adapt it to the orographic conditions of Mexico, which largely account for the great biodiversity.

These modifications include, among others, the application of Lang’s index (total annual precipitation/mean annual temperature), percent winter rainfall, thermal zoning, and the use of a plant species locally called gobernadora (Larrea tridentata) as a reference for the distribution of arid regions in northern Mexico and southwestern United States. This system has been used in several issues of official map collections of Mexico.

The other climate classification system is the Worldwide Bioclimatic Classification System (WBCS), which establishes the relationships of reciprocity between the potential vegetation and the bioclimatic thresholds associated with the proposed indices, which characterize the system’s typological units (macrobioclimate, bioclimate and thermotype). The different categories recognized at each level allow setting the type of system defined by the geographical distribution, thermal and ombric figures on an annual, seasonal or monthly basis, and that show specific discriminating threshold values.

We analyzed daily data recorded in 1303 weather stations of Mexico with over 30 years of information between 1955-2008, obtained from the National Meteorological Service (SMN). After application of different homogeneity tests, these data were classified according to the two systems. In the SM, the diagnosis was obtained using the Modifica Program; in the case of the WBCS, the classification was made using a worksheet.

The equivalence between the two systems was explored by comparing the climatic types obtained from the SM, grouped by rainfall regime with macrobioclimates, organized by the degree of moisture with bioclimates and ombrotypes, and sorted by thermal areas with the thermotypes of WBCS. The results obtained are shown in tabular format.

The comparison of the hierarchical units of highest rank in both systems evidences that the climates with summer and intermediate rainfall regime match the Tropical macrobioclimate, while those with winter rainfall regime correspond to the Mediterranean macrobioclimate.

The overall agreement found between SM and Bioclimates was 98%, reaching 100% in some cases, particularly regarding the pluvial and pluvialseasonal bioclimates; the agreement for dry climate types was 70%.

The equivalence between ombrotypes and subtypes grouped according to the humidity conditions of the SM was 100% for the categories of lower humidity and above 75% for humid categories.

The two systems share many similarities in the humidity conditions; nonetheless, the equivalencies between the thermotypes of the WBCS and the thermal zones of the SM are approximations, as the former includes several thermal zones of the SM.

The equivalences found were used to label the different polygons on the map of climates published by CONABIO, at scale one to one million, and the maps of Macrobioclimates and Bioclimates were drawn. These were compared with maps previously published by several authors, noting that the ones obtained in this work agree with them in general terms; the differences found are attributed to the methodologies used in the definition of the bioclimatic and macroclimatic cartographies, as well as to the scale of maps.

Keywords : Mexico; climate; bioclimate; classifications; Garcia; Rivas-MartInez.