Duval, Valeria Soledad; Benedetti, Graciela; Campo, Alicia María; Climate-vegetation relationship: adaptations of the jarillal community to the semi-arid climate, Lihué Calel National Park, La Pampa province, Argentina; National Autonomous University of Mexico. Institute of Geography; Geographic Investigations; 88; 12-2015; 33-44
The study of vegetation from Geography focuses on the analysis of its spatial distribution and the factors that affect it. One of them is the climate that determines the characteristics of the plant formations and, on a larger scale, the communities. The objective of this work is to analyze the climate-vegetation relationship by studying the adaptations of the jarillal community with respect to the semi-arid climate in the Lihué Calel National Park, Argentina. For this, the water balance of Thornthwaite and Mather is carried out using data from the park’s meteorological station belonging to the period 1995-2010. Bioclimatic indices are applied and stands are made to know the floristic composition and physiognomy of the vegetation. The adaptive responses identified in the surveyed plant individuals are analyzed and it is verified that the semi-arid climate conditions the morphology and physiognomy of the park. The presence of xerophytic vegetation with a predominance of bushes and open cover is demonstrated. Among the adaptations observed are the loss of leaves in the unfavorable season, the replacement of leaves by thorns, small and resinous leaves, inclination of the leaf and extensive roots.
The study of vegetation from the Geography perspective focuses on the analysis of the spatial distribution and on the factors affecting it. One of these factors is the climate, which determines the characteristics of the vegetation and, on a larger scale, of the communities. The aim of this paper is to analyze the climate-vegetation relationship by studying adaptations of the jarillal community regarding the semiarid climate in the Lihué Calel National Park, Argentina. Therefore, this contribution is concerned with the knowledge of the characteristics of the environment in order to understand how vegetation responds to certain phenomena, so management of protected areas will be more suitable. Lihué Calel National Park is a national protected area located in the south-center of La Pampa province, Argentina. According to Cabrera (1976) the area belongs to the floristic province of “monte” and the climate is warm and dry. In the interest to achieve the goals of this paper, Thornthwaite and Mather´s water balance was done. The data was collected from a weather station that belongs to the national park, for the period 1995-2010. Emberger›s pluviothermic coefficient, Lang´s rainfall index, De Martonne´s aridity index and Currey´s continentality index were analyzed. In addition, ten stands or plots of vegetation were placed to determine the floristic composition and the vegetation physiognomy. Then, plants species were identified as individuals and their adaptive responses were also analyzed. In conclusion, the survey verified that semi-arid climate conditions determine the morphology and the appearance of jarillal. Climate analysis shows that for the period 1995-2010 the average annual temperature is 16.2° C and reveals that thermal summers and winters are well differentiated. Large water deficit is defined, because water balance indicates that the evapotranspiration exceeds precipitation during every month of the year. According to Thornthwaite’s criteria, the area is a semiarid climate type. With the analysis of other bioclimatic indices, more information is obtained: Lang´s index value is 25.7 (arid), Emberger’s index is 41.8 (semiarid), De Martonne’s index is 15.9 (that refers to a semi-arid climate) and, at last, Currey’s index certified the existence of a continental climate because the result was 1.16. Vegetation was surveyed and the result was quite interesting: 1 508 individuals that belong to 33 species. The percentage is: shrubs 57.6%, grasses 36.4% and trees 6.1%. Most of them were evergreen and only some deciduous. The distribution of vegetation in Lihué Calel responds to the semi-arid conditions. Some adaptations were observed like the development of the deep root system with an horizontal pattern in order to absorb the water from the soil, the loss of leafs in the unfavorable season, the replacement of leaves by thorns, small resinous leaves, leaf tilting and extensive roots, among others. The dominant plant of the jarillal is Larrea divaricata and it is considered as a xerofite plant. The process indicates that when stomata are open, transpiration rates increase; when they are closed, transpiration rates decrease. The Cactaceae family is represented by two species: Opuntia puelchana and Cereus aethiop. They are considered succulent plants that keep humidity inside. During rainy periods they absorb large amounts of water that they then use during the dry periods. These types of studies are relevant to understand how plants adapt to different environmental events, whether they are natural and/or anthropogenic. As a reference, in 2003, major fires occurred inside the National Park and they affected 7 000 hectares. The resinous leaves of the jarilla helped to propagate the fire all around the place. The next phase of the investigation process will be related to the physiological and morphological properties, through chemical analysis, so the adaptation of vegetation can be tested. With these new studies, the final purpose will be reached: good practice for plant conservation.
National Autonomous University of Mexico. Institute of Geography
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LIHUE CALEL NATIONAL PARK
Climate-vegetation relationship: adaptations of the jarillal community to the semi-arid climate, Lihué Calel National Park, La Pampa province, Argentina
Climate-vegetation relationship: adaptations of jarillal community to the semiarid climate. Lihué Calel National Park, province of La Pampa, Argentina
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Fil: Duval, Valeria Soledad. National University of the South. Department of Geography and Tourism; Argentina. Buenos Aires province. Governorate. Commission of Scientific Investigations; Argentina
Fil: Benedetti, Graciela. National University of the South. Department of Geography and Tourism; Argentina
Fil: Campo, Alicia María. National Council for Scientific and Technical Research. Conicet Scientific Technological Center – Bahía Blanca; Argentina. National University of the South. Department of Geography and Tourism; Argentina