TREE HEALTH ASSESSMENT IN AN INSTITUTIONAL GREEN SPACE: INAOE CASE STUDY.

Knowledge of the health condition of urban trees is fundamental for making decisions regarding management and resource allocation. The objective of this study was to determine the current health status of the trees at the National Institute of Astrophysics, Optics, and Electronics (INAOE) in San Andres Cholula, Mexico. Five health indicators previously used in urban forests were assessed. The structure and diversity indicator indicated the existence of 2210 trees, mostly (58.8 %) of small size (< 20 cm average diameter at breast height), 20 botanical families, and 32 tree species. The crown condition and its variables indicated high foliage transparency (> 40 %) in some of its species and low percentages of dieback. Live crown ratio and crown density were moderate in eight and six species, respectively. The tree damage indicator showed the existence of 44 damaging agents in 956 trees (43.3 % of the total), highlighting the ball moss (Tillandsia recurvata), the felt fungus of evergreen ash (Septobasidium sp.) associated with an armored scale, the same fungus also affecting white cedar (Hesperocyparis lusitanica) in association with another scale (a new record), and two bark beetles, Hylesinus aztecus in evergreen ash, and Phloesinus sp. in white cedar. Regarding the mortality indicator, 75 trees (3.3 %) were recorded. Finally, the soil condition indicated that the pH was close to neutral, with electrical conductivity values above 2 dS m-1 and a low beneficial mycoflora population. All these factors, together with the imbalance in tree diversity, high planting density, compacted soils, and the presence of risky trees, are negatively affecting the health of INAOE's tree community. [ABSTRACT FROM AUTHOR]