首页> 外文期刊>Trees. Structure and Function >Summer-drought constrains the phenology and growth of two coexisting Mediterranean oaks with contrasting leaf habit: implications for their persistence and reproduction.
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Summer-drought constrains the phenology and growth of two coexisting Mediterranean oaks with contrasting leaf habit: implications for their persistence and reproduction.

机译:夏季干旱限制了两种并存的地中海橡木的物候和生长,并具有相反的叶习性:对其持久性和繁殖的影响。

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This study analyses how coexisting evergreen and deciduous oaks adjust their phenology to cope with the stressful Mediterranean summer conditions. We test the hypothesis that the vegetative and reproductive growth of the winter deciduous (Quercus faginea Lam.) is more affected by summer drought than that of the evergreen [Quercus ilex L. subsp. ballota (Desf.) Samp.]. First, we assessed the complete aboveground phenology of both species during two consecutive years. Shoot and litter production and bud, acorn and secondary growth were monitored monthly. Second, we identified several parameters affected by summer conditions: apical bud size, individual leaf area (LA), leaf mass per area (LMA) and acorn yield in both species, and leaf-fall in Q. faginea; and analysed their variation over 10 years. Q. ilex performed up to 25% of shoot growth and most leaf development during summer, whereas Q. faginea completed most of both phenophases during spring. Secondary growth was arrested in summer under drought conditions. Approximately, 30-40% of bud and 40-50% of acorn growth was undertaken during summer in both species. Summer drought related to differences in LA, LMA and leaf senescence, but not to acorn yield. Both species had similar year-to-year patterns of acorn production, though yields were always lower in Q. faginea. Bud size decreased severely in both species during extremely dry years. In Q. ilex, bud size tended to alternate between years of large and small buds, and these patterns were followed by opposite trends in stem length. In Q. faginea, bud size was more stable through time. Q. ilex was more phenologically active during summer than Q. faginea, indicating a higher tolerance to drought. Furthermore, bud and fruit growth (the only two phenophases that both species performed during summer) were more severely affected by summer drought in Q. faginea than in the evergreen. The differential effects of summer drought on key phenophases for the persistence (bud growth) and colonization ability (fruit production) of both species may have consequences for their coexistence.
机译:这项研究分析了常绿和落叶橡树并存如何调整其物候特性,以应对地中海夏季的压力。我们检验了以下假设,即冬季落叶( Quercus faginea Lam。)的营养生长和生殖生长比常绿[ Quercus ilex L]受夏季干旱的影响更大。亚种 ballota (Desf。)Samp。]。首先,我们评估了连续两年中两个物种的完整地上物候。每月监测芽和凋落物的产生以及芽,橡子和次生的生长。其次,我们确定了受夏季条件影响的几个参数:两种物种的根尖芽大小,单叶面积(LA),每面积叶质量(LMA)和橡子产量,以及Qi中的叶落量。 faginea ;并分析了他们10年的变化。问:夏季,冬青属植物的嫩芽生长和大部分叶片发育最多达到25%,而 Q。在春季,faginea 完成了这两个表位的大部分。夏季在干旱条件下阻止了次生生长。在两个物种中,大约在夏季都进行了30-40%的芽和40-50%的橡子生长。夏季干旱与LA,LMA和叶片衰老的差异有关,但与橡子产量无关。两种品种的橡子产量年比相似,尽管在Q期产量始终较低。 faginea 。在极度干旱的年份中,两个物种的芽大小均急剧下降。在 Q。 ilex ,芽的大小倾向于在大芽和小芽的年间交替变化,并且这些模式之后的茎长趋势相反。在 Q。 faginea ,随着时间的推移,芽的大小更加稳定。问: ilex 在夏季比 Q更活跃。 faginea ,表明对干旱的耐受性更高。此外,发芽和果实的生长(两个物种在夏季都进行的仅有的两个表相)在Q期受到夏季干旱的严重影响。 faginea 而不是常绿。夏季干旱对这两个物种的持久性(芽生长)和定植能力(果实产量)的关键性状期的不同影响可能会影响它们的共存。

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