期刊
TREE PHYSIOLOGY
卷 38, 期 2, 页码 159-172出版社
OXFORD UNIV PRESS
DOI: 10.1093/treephys/tpx157
关键词
ecophysiology; functional xylem traits; secondary growth; stable isotopes; water-use efficiency; wood anatomy
类别
资金
- K-Egokitzen project (Basque Government)
- Spanish Ministry of Economy Fundiver project [CGL2015-69186-C2-1-R]
- Juan de la Cierva research contract (Spanish Ministry of Economy and Competitiveness) [FJCI-2014-19615]
- [JCI-2012-12508]
- [CGL2014-55976-R]
The ability of trees to cope with climate change is a pivotal feature of forest ecosystems, especially for rear-edge populations facing warm and dry conditions. To evaluate current and future forests threats, a multi-proxy focus on the growth, anatomical and physiological responses to climate change is needed. We examined the long-term xylem adjustments to climate variability of the temperate Quercus robur L. at its rear edge and the sub-Mediterranean Quercus pyrenaica Willd. Both species coexist at a mesic (ME, humid and warmer) and a xeric (XE, dry and cooler) site in northern Spain, the latter experiencing increasing temperatures in recent decades. We compared xylem traits at each site and assessed their trends, relationships and responses to climate (1960-2008). Traits included basal area increment, earlywood vessel hydraulic diameter, density and theoretical-specific hydraulic conductivity together with latewood oxygen (delta O-18) stable isotopes and delta C-13-derived water-use efficiency (iWUE). Quercus robur showed the highest growth at ME, likely through enhanced cambial activity. Quercus pyrenaica had higher iWUE at XE compared with ME, but limited plasticity of anatomical xylem traits was found for the two oak species. Similar physiological performance was found for both species. The iWUE augmented in recent years especially at XE, likely explained by stomatal closure given the increasing delta O-18 signal in response to drier and sunnier growing seasons. Overall, traits were more correlated at XE than at ME. The iWUE improvements were linked to higher growth up to a threshold (similar to 85 mu mol mol(-1)) after which reduced growth was found at XE. Our results are consistent with Q. pyrenaica and Q. robur coexisting at the central and dry edge of the climatic species distribution, respectively, showing similar responses to buffer warmer conditions. In fact, the observed adjustments found for Q. robur point towards growth stability of similar rear-edge oak populations under warmer climate conditions.
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