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Universidad Autónoma de Nuevo León (2013)

Caracterización estructural de dos matorrales del noreste de México

Mora Donjuán, Carlos Alberto

Titre : Caracterización estructural de dos matorrales del noreste de México.

Auteur : Mora Donjuán, Carlos Alberto

Université de soutenance : Universidad Autónoma de Nuevo León

Grade : Maestría en Ciencias Forestales UANL, 2013

The bushes are vegetation communities that are recognized for being of short stature and their stems branch above the ground. These are the vegetation communities more abundant in México, they covering about 45% of the surface. They are distributed throughout the north of the country and extended some parts of central and southern (Oaxaca). There are many kinds of bushes, these variations in the type of bushes are due for the different ecological where they develop, especially temperature, precipitation and kind of ground. The bushes are located in all the soil types and altitudinal levels in north of México.
This investigation was divided in six chapters for a best comprehension. In all the investigations they were performed characterizations and evaluations of two xerophytic bushes, the Tamaulipan thornscrub and the microphyll desert bush. Both bushes are characterized structurally, evaluating their composition through their abundance, dominance, frequency and its composition, species richness, diversity (alpha and beta), the richness of vegetation community. In the Tamaulipan thornscrub” bush it was also consider the mixture and species evenness, dimensional differentiation and special distribution. To the microphyll desert bush was estimated (also the mentioned indexes before) the Pretzsch index to analyze vertically the vegetation in each one of the strata (high, medium and low). Also of the performances, it was making a comparative investigation to assess the effect of the animal husbandry activity in the vegetation community from Tamaulipan thornscrub.
The chapter second assessed the composition and the diversity of the arboreal and shrub species from a reference area of the Tamaulipan thornscrub. The results registered 21 species, distributed in 20 different genres and 14 families, where the more representative family was Fabaceae with seven species. The studied community integrates principally at the species Acacia amentacea, Diospyros texana and Havardia pallens with an importance value index of 24.94%, 15.57% and 13.01% respectively. The area registred an diversity´s index of H´=1.94 and a specie richness of DMg=2.0.
The third chapter characterizes structurally a reference ecosystem from the registred in the northwest of Mexico, where is estimated the Uniformity of Gadow´s indexes which records a value of Wi=0.58±0.22, species’ mixture a value of Mi=0.62±0.31 ; and of dimensional differentiation ; diameter Uid=0.50±0.018 and of heigh, Uih=0.58±0.34. The results show that the structure of the four areas are highly homogeneous in dimensional differentiation ; the values of Gadow´s uniformity indicate a distribution with tendency toward randomness and the species´mixture two places show vicinity with three or four individuals, while the two remaining sites show vicinity with one or two different individuals about it.
In the chapter IV is made a comparative analysis in three areas of the registred (Reference, Regeneration and Livestock), to evaluate the impact of the livestock in the composition and tree and bush diversity. The results recorded 22 species, distributed in 20 genres and 14 families. The ecological weight is represented by three species ; in the reference area, Diospyros texana ; Regeneration, Acacia farnesiana ; and livestock, Prosopis laevigata. The results of the investigation show that the livestock reduces the abundance significantly, dominance and alpha diversity of the tree and bush species communities ; and that these resulting plant communities show a low species similarity.
The fifth chapter characterized a desert bush microphill with livestock history, assessed the impact in the livestock in the composition and plant diversity. The results show Gutierrezia microcephala like the specie more abundant with 584 N/ha (33%), followed by Prosopis glandulosa with 368 N/ha (21%) ; the specie that shows more dominance and frequency was P. glandulosa with 1574 m2/ha and with presence in 19 of the 25 places, which affects in the IVI, being the specie which presents the highest value with 34.6%. Obtaining a value of DMg=2.29 to species richness and a diversity index of H´=1.87.

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Page publiée le 5 décembre 2016, mise à jour le 13 août 2017