Canopy condition: Health indicator of urban trees in the San Juan de Aragón Forest, Mexico City

Urban green areas provide various services to society and the environment. The Bosque San Juan de Aragón is one of the few green areas in the northeast of Mexico City and the current condition of its trees in terms of health is not known with precision. In the present study, the protocol for the crown condition indicator was implemented and adapted in 28 circular plots of 0.1 ha, randomly established in the aforementioned forest. All trees within each plot were measured for normal diameter (ND) and total height (TA), and their taxonomic classification, crown condition and plantation density were determined. For crown condition, six variables were measured: proportion of live crown (PLC), crown density (CD), crown transparency (CTR), dieback (DB), crown position (CP) and light exposure (LE). The first four were measured in 5% classes and the remaining two were measured on an ordinal scale. A total of 760 trees were evaluated, grouped into 10 families, 11 genera and 12 species. The average values for the crown variables were 56.37% PLC, 44.38% CD, 4.04% DB and 38.4% CTR. Only PLC reached the established standards of tree health found in other studies, while CD was low and CTR and DB values were high.