Morphological and biochemical changes in Quercus humboldtii in response to warmer and polluted urban areas in a tropical Andean city

Abstract

Abstract The rapid growth of urban population has significantly changed human settlement patterns, leading to a decline in air quality and changes in climatic conditions in urban areas. Trees are recognized as nature-based solutions because they can remove particles from the air and regulate the climate. However, trees are negatively affected by pollution and temperatures, which represent a challenge for urban planning, management, and human health. To assess the impact of urban pollution and warmer climates on functional traits, we conducted a study using Quercus humboldtii, an endangered tree species endemic to Colombia and Panamá that dominates Andean forests and urban green areas in Bogotá. We selected three localities with contrasting pollution levels and climate conditions and measured 10 morphological and biochemical traits in six individuals at each location. Our findings revealed that Q. humboldtii adjusted morphological and biochemical traits in response to the environmental challenges posed by urban environments. The functional strategies varied between individuals with thin and large leaves and acidic pH in the colder and unpolluted native forest, while others displayed a conservative resource strategy (high leaf dry matter content) and neutral pH in the warmer and most polluted locality. Despite these differences, several traits indicate that Q. humboldtii is not a species tolerant to pollution. This is further supported by the air pollution tolerance index (APTI) values. Our results suggest that Q. humboldtii should be planted in areas of Bogotá with low pollution levels in order to promote its long-term survival and support ecosystem services.