How Do Tilia cordata Greenspire Trees Cope with Drought Stress Regarding Their Biomass Allocation and Ecosystem Services?

Abstract

In the context of climate change, drought is likely to become more frequent and more severe in urban areas. Urban trees are considered to play an important role in fixing carbon, improving air quality, reducing noise and providing other ecosystem services. However, data on the response of urban trees to climate change, particularly to drought, as well as the relationship between their below- and above-ground processes in this context, are still limited, which prevents a comprehensive understanding of the role of urban trees in ameliorating some of the adverse effects of climate change and their ability to cope with it. To investigate whole-plant responses to water shortages, we studied the growth of Tilia cordata Greenspire, a commonly planted urban tree, including development of its roots and stem diameter, leaf parameters and the harvested biomass. Our results showed that this cultivar was susceptible to drought and had reduced biomass in all three compartments: branch (30.7%), stem (16.7%) and coarse roots (45.2%). The decrease in the root:shoot ratio under drought suggested that more carbon was invested in the above-ground biomass. The development of fine roots and the loss of coarse root biomass showed that T. cordata Greenspire prioritised the growth of fine roots within the root system. The CityTree model’s simulation showed that the ability of this cultivar to provide ecosystem services, including cooling and CO2 fixation, was severely reduced. For use in harsh and dry urban environments, we recommend that urban managers take into account the capacity of trees to adapt to drought stress and provide sufficient rooting space, especially vertically, to help trees cope with drought.

A single tree model to consistently simulate cooling, shading, and pollution uptake of urban trees

“…The introduction of such a feature would also provide the means for considering the potential positive effects of reduced ozone concentrations on the water balances. In addition, seasonal responses of trees, such as leaf shedding, xylem embolism, and higher root turnover or the death of trees might be introduced in response to pollution or drought stress (Stratópoulos et al 2019 ; Zhang et al 2019 ). Finally, not only direct temperature effects but also changes in the air humidity should be simulated based on evaporation, which also improves the human thermal comfort and thus may add to the benefit of urban tree abundance (Upreti et al 2017 ; Wang et al 2018 ).…”

Variable Fall Climate Conditions on Carbon Assimilation and Spring Phenology of Young Peach Trees

“…Warmer temperature, specifically during the night, inside the greenhouse may have slowed down root growth on DS trees due to higher respiration [ 14 ] or growth cessation [ 37 ]. Increased R:S ratio have been previously linked to improved water use efficiency (WUE) as a physiological response for better coping with water deficit [ 38 ]. The DS trees had both lower leaf WUE (data not shown) and R:S ratio than NS trees, but each of these measurements were taken in different seasons (WUE in fall during gas exchange measurements, R:S ratios in spring) in this study.…”

Effects of Drought on the Phenology, Growth, and Morphological Development of Three Urban Tree Species and Cultivars

“…We employed an experimental setting where we simulated the conditions of a sustained drought to investigate the physiological and growth responses of the trees [15,28] as well as their phenological timings, the architecture of the root systems, and the carbon partitioning and allocation. The rainfall exclusion experiment started in May 2017 and was conducted throughout the growing period of the year until November.…”