Differences in physiological and biochemical responses to summer drought of Pinus nigra subsp. pallasiana and Pinus brut
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ORIGINAL PAPER
Differences in physiological and biochemical responses to summer drought of Pinus nigra subsp. pallasiana and Pinus brutia in a natural mixed stand Ays¸ e Deligo¨z1 • Fatma Go¨kc¸e Cankara1
Received: 12 March 2018 / Accepted: 18 October 2018 Northeast Forestry University 2019
Abstract Understanding how tree species respond to drought in their natural environment is needed to predict forest adaptation and management practices under global environmental changes. This study was carried out to determine and compare physiological and biochemical responses to variations in environmental conditions during summer drought of mixed natural stands of Pinus nigra Arn. subsp. pallasiana (Lamb.) Holmboe and Pinus brutia Ten. Midday xylem water potential (Wmd), water relations, photosynthetic pigments, total soluble sugar and proline contents were investigated during the growing season. Wmd followed a similar seasonal trend in both species but P. nigra subsp. pallasiana had higher Wmd than P. brutia. The Wmd gradually decreased from June, reached its lowest value in August, and then increased again. Gradual decreases in the osmotic potential at turgor loss point (WgTLP) were observed during the summer. Generally, WgTLP was lower in P. brutia. Total soluble sugars decreased from April to June for P. brutia, then increased and stayed relatively constant August to October. Similar changes were found at lower values in P. nigra subsp. pallasiana. Prolin accumulation and photosynthetic
Project funding: The work was supported by the Suleyman Demirel University, Scientific Research Projects Coordination Unit (Project Number: 4513-YL1-15). The online version is available at http://www.springerlink.com Corresponding editor: Tao Xu. & Ays¸ e Deligo¨z [email protected] 1
Faculty of Forestry, Isparta University of Applied Sciences, 32260 Isparta, Turkey
pigments were higher in P. brutia. The results indicate that physiological and biochemical responses of both species against changing environmental conditions were in different degrees but followed similar trends. P. nigra subsp. pallasiana is more sensitive to summer drought than P. brutia in their natural environment. Keywords Pinus nigra subsp. pallasiana Pinus brutia Osmotic potential Photosynthetic pigments Soluble sugars Proline Summer drought
Introduction An increase in climate extremes (low or high temperatures, drought or flooding) is expected as a consequence of climate change. These effects have already begun to be felt throughout the Mediterranean. Rapid and acute changes in climatic conditions within the next 100 years will have a significant impact on Mediterranean forests (Solomou et al. 2017). Recently, increased tree mortality in some areas has been linked to global climate change through combinations of drought and high temperatures (Sala et al. 2010; Mildrexler et al. 2016; Buras et al. 2018). An increase in temperature combined with low water availability, especially in the summer months, is expected to lead to photosynthesis de
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