Abstract

ABSTRACT Green areas in cities provide several benefits to people, however, several biotic and abiotic agents affects the tree’s health. The main goals of this research were to identify tree damages and to assess the impact of mistletoe on dendrometric variables and the crown condition. Four thousand, seven hundred seventy-five trees were evaluated in 16 green areas of eight Mayoralties in Mexico City; each tree was labeled, and total tree height (Th), diameter at breast height (DBH), damage agents (up to three types), and the crown variables: Live crown ratio (Lcr), Crown dieback (Cdie), Mistletoe severity (Ms) and Crown position (Cpo) were recorded. Of the assessed trees, 3318 presented damage. For the type of damage 1, the mistletoes Cladocolea and Struthanthus showed an average incidence of 42%. For type 2, 20 agents and type 3, 11 were identified. Mechanical wounds, sucking insects, vandalism, and cankers were the most common damages. Based on the Principal Component Analysis (PCA), trees of all diameters and heights were infected, however, Struthanthus was associated with taller and larger diameter trees. Lcr was lower, and Cdie and Ms were higher in infected trees. About Cpo, dominant and codominant trees showed the highest levels of severity by mistletoe. The most affected tree genera were Ulmus and Populus (low Lcr and high Cdie and Ms). Cladocolea was found toward southern Mayoralties, and Struthanthus at the north. It is recommended to assess at least two types of damage on each tree, as this will provide a more complete picture of its health. This is the first study in Mexico on the impact of mistletoe on tree crown variables

Highlights

  • RESUMO – As áreas verdes nas cidades oferecem muitos benefícios para as pessoas, no entanto, vários agentes bióticos e abióticos afetam a saúde das árvores

  • Seven hundred seventyfive trees were evaluated in 16 green areas of eight Mayoralties in Mexico City; each tree was labeled, and total tree height (Th), diameter at breast height (DBH), damage agents, and the crown variables: Live crown ratio (Lcr), Crown dieback (Cdie), Mistletoe severity (Ms) and Crown position (Cpo) were recorded

  • For the type of damage 1, the mistletoes Cladocolea and Struthanthus showed an average incidence of 42%

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Summary

Introduction

RESUMO – As áreas verdes nas cidades oferecem muitos benefícios para as pessoas, no entanto, vários agentes bióticos e abióticos afetam a saúde das árvores. The program considers dasometric measurements such as total tree height, diameter at breast height, crown condition, tree damage and others (Stolte et al, 2002) These indicators have been applied in the urban scenario of different green areas of the world (Cumming et al, 2001) and, recently, in Mexico, in Alameda north, east and south (Zaragoza-Hernández et al, 2014), and in the urban park San Juan de Aragon (SaavedraRomero et al, 2016; 2019; 2020). Due to the lack of studies on the current health condition of the urban green areas, the main goals of this research was to identify the different types of tree damage and to assess the impact of mistletoe on dasometric and crown condition variables in tree genera and green areas of Mexico City

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