Effects of climate trends and drought events on urban tree growth in Santiago de Chile

Abstract

Urban trees and the services they provide (e.g., evapotranspirational cooling,

shading, recreation, carbon storage, air pollution filtering) can have major effects on the

microclimate of a city, although the growth conditions are often inadequate to ensure tree vitality

and growth, negatively affecting their beneficial effects. In a worldwide dendrochronological

study on ten urban tree species in four climatic zones, the growth and impacts of common urban

tree species were assessed. This paper focuses on the results for Robinia pseudoacacia L. in the

Mediterranean climate city of Santiago de Chile, highlighting the faster growth of the studied

black locust trees since 1960 than its growth in the years before 1960. Furthermore, black

locust displayed the best growth when situated closer to the city center than the city periphery

and when in the northern and western parts of Santiago de Chile. The species characteristics of

black locust also revealed an immediate negative growth reaction to drought events, followed

by a rapid recovery, which was similarly influenced by the direction from and distance to the

city center of the growing site. The results underline the overall worldwide findings on urban

tree growth that indicate that a city climate with an extended growing season and increased

temperatures can lead to improved growth of urban trees in the Mediterranean climatic zone.

However, with increased growth, more rapid ageing and tree death might follow, leading to

increased costs for new plantings and tree management.