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Eleven populations of Taxus globosa were located and evaluated along of the Sierra Madre Oriental in the States of Nuevo Leon and Tamaulipas, Mexico. A complete inventory of the individuals in all Taxus globosa populations was recorded; data of height, diameter, canopy cover and density were also evaluated. The population data were organized in databases on rank classes into six height categories, seven canopies cover categories and seven diameter categories. A χ² test indicates that all the populations showed a normal distribution. The canopy cover and diameter variables showed higher values in correlation analysis (r = 0.9). The population curve tendency on height, canopy cover and diameter shows that isolated or inaccessible populations of Taxus globosa Las Tinajas, Julilo and La Camotera are the populations with more young individuals than the rest of the northeastern populations. [ABSTRACT FROM AUTHOR]

The effect of land use on the structural diversity of Tamaulipan thornscrub in northeastern Mexico was examined. The objective was to determine whether land use modified diversity, ecological indicators, structural and vertical distribution of trees and shrubs. The analysis was performed by comparing three ecosystems with different land use history: extensive cattle grazing, traditional agriculture and clear cutting with 21 year of abandonment. The methodology used was a combination of rectangular sites and a sampling analysis called "structural group of four trees". Results showed differences in diversity, ecological indicators, vertical distribution and dimensional structure. [ABSTRACT FROM AUTHOR]