Primary and secondary growth of Pinus halepensis are more sensitive to inter-annual drought variability than to 14 years of rainfall exclusion in a Mediterranean forest.
Léa Veuillen, Prévosto Bernard, Caraglio Yves, Martin Nicolas, Simioni Guillaume, Vennetier Michel, Cailleret Maxime
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引用次数: 0
Abstract
Background and aims: With ongoing climate change, the impact of droughts of increasing intensity on forest functioning is of critical concern. While the adverse effects of drought on tree secondary growth have been largely documented both at the tree and stand scales, our understanding of how primary growth morphological traits, which control crown development, respond to drought remains limited - especially in the long term.
Methods: Based on 14 years of monitoring of four primary growth morphological traits (e.g., shoot elongation, polycyclism rate, branching and needle length) and stem secondary growth in a rainfall exclusion experiment, we investigated (i) the climatic drivers of aboveground growth and (ii) the effect of long-term exacerbated drought conditions on the growth response to drought in a mature Pinus halepensis stand.
Key results: Aboveground growth was strongly and negatively impacted by drought duration during the current year (stem secondary growth), the previous year (polycyclism) and both years (branching, shoot length), and by drought during spring (needle length). While excluding 30% of the incoming rainfall did not significantly affect the number of ramifications, polycyclism rate or stem secondary growth, it reduced needle and shoot lengths by 14.3 and 7.7% over the entire study period, respectively. However, this effect is significant only in the first years after the treatment was established. Such acclimation to exacerbated drought conditions is also reported in the drought-growth relationships which are similar among treatments, except for needles that were slightly shorter under a similar level of drought stress in the exclusion.
Conclusions: Our study highlights the key acclimation capacity in the primary and secondary growth response of P. halepensis to drought. In addition to tree structural adjustments, the relatively limited effect of the 30% rainfall exclusion may also be caused by (i) the substantial inter-annual rainfall variability typical of Mediterranean climates, which modulates the exclusion effect on drought duration, and (ii) the inherent inter-individual variability in drought sensitivity.
期刊介绍:
Annals of Botany is an international plant science journal publishing novel and rigorous research in all areas of plant science. It is published monthly in both electronic and printed forms with at least two extra issues each year that focus on a particular theme in plant biology. The Journal is managed by the Annals of Botany Company, a not-for-profit educational charity established to promote plant science worldwide.
The Journal publishes original research papers, invited and submitted review articles, ''Research in Context'' expanding on original work, ''Botanical Briefings'' as short overviews of important topics, and ''Viewpoints'' giving opinions. All papers in each issue are summarized briefly in Content Snapshots , there are topical news items in the Plant Cuttings section and Book Reviews . A rigorous review process ensures that readers are exposed to genuine and novel advances across a wide spectrum of botanical knowledge. All papers aim to advance knowledge and make a difference to our understanding of plant science.