Diversity, structure and health of trees in green areas of Texcoco city, Mexico

Abstract

Urbanization without proper planning is the cause of a number of ecological problems, including degradation and loss of vegetation. Analysis of trees’ diversity and structure is relevant due to their relationship with tree health and the trees’ consequent capacity to provide environmental, social and economic benefits. Trees in favorable conditions have a direct impact on urban sustainability, planning and management. The aim of this study was to evaluate the health of trees located in green areas of the city of Texcoco de Mora, Mexico and its relationship with the structure, diversity and typology of urban green areas, in order to provide management and planning recommendations. 21 green areas of the city were evaluated and a tree census was carried out. Richness and diversity indices were used to analyze tree vegetation and chlorophyll fluorescence (Fv/Fm) as indicators of tree health. 1,543 trees were registered, including 53 species distributed in 36 genera and 24 families. The evaluation revealed that the urban trees were made up mostly of young individuals, and showed tree density to be higher than other green spaces in Mexico. The use of richness and diversity indices allowed the researchers to evaluate the presence of a greater number of non-native species and denoted the differences between between Urban Green Areas (AVU). Evaluation of chlorophyll fluorescence (Fv/Fm) indicated that the trees are under stress conditions (Fv/Fm < 0.780). No correlation was found between the values of Fv/Fm, richness and diversity in the studied areas, however, the shape and surface of the green areas were correlated with the aforementioned indices.