Responses of Contrasting Tree Functional Types to Air Warming and Drought

Elisabet Martínez-Sancho,Lizeth K Vásconez Navas,Annette Menzel,Hannes Seidel,Isabel Dorado-Liñán

doi:10.3390/f8110450

Elisabet Martínez-Sancho, Lizeth K Vásconez Navas + Show 3 more

Open Access

https://doi.org/10.3390/f8110450

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Abstract

Climate change-induced rise of air temperatures and the increase of extreme climatic events, such as droughts, will largely affect plant growth and hydraulics, leading to mortality events all over the globe. In this study, we investigated the growth and hydraulic responses of seedlings of contrasting functional types. Pinus sylvestris, Quercus spp. and Castanea sativa seedlings were grown in a common garden experiment under four treatments: control, air warming, drought and their combination during two consecutive growing periods. Height and diameter increments, stomatal conductance and stem water potentials were measured during both growing seasons. Additionally, hydraulic parameters such as xylem-specific native and maximum hydraulic conductivities, and native percentage of loss of conductivity were measured at the end of the entire experiment. Our results clearly pointed to different adaptive strategies of the studied species. Scots pine displayed a relatively isohydric behavior with a strict stomata control prohibiting native embolism whereas sweet chestnut and oak as relatively anisohydric species displayed an increased loss of native conductivity as a results of low water potentials. Seasonal timing of shoot and diameter growth also differed among functional types influencing drought impacts. Additionally, the possibility of embolism reversal seemed to be limited under the study conditions.

Highlights

Climate change is certainly affecting forests at different spatial and temporal scales [1]
Among the climate changes forecasted by the last Intergovernmental Panel on Climate Change (IPCC) report [4], a rise of mean temperatures and an irregular rainfall distribution, and an increase in frequency and intensity of extreme climate events such as drought are predicted by the end of 21th century for Europe
We focused on the following questions: (i) Are there inter-specific differences in the response to prolonged drought and warming? (ii) Is competition enhancing drought stress? (iii) Is the relation between stomatal conductance and water potential equal among species? (iv) Do the studied species recover their hydraulic conductivity after experiencing very low water potentials?

Summary

Introduction

Climate change is certainly affecting forests at different spatial and temporal scales [1]. Forests are especially sensitive to climate change because trees have a long life-span reducing their ability to adapt to environmental changes [2]. Several mortality events have been observed across different ecosystems, species and continents triggered by drought and heat spells; pointing to a global vulnerability of forests to the ongoing climate change [3]. The risk of forest mortality may increase as a consequence of future detrimental climatic conditions. Since forest ecosystems play a major role in different natural cycles, climate change-induced mortality would imply, for instance, changes in ecological communities leading to a loss of ecosystem services [5].

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