کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4525287 1625625 2015 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Contrasting leaf phenological strategies optimize carbon gain under droughts of different duration
ترجمه فارسی عنوان
استراتژی های فنولوژیک برگ سبز به دلیل افزایش خسارات ناشی از دوره های مختلف، افزایش کربن را افزایش می دهد
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
چکیده انگلیسی


• Leaf phenology during drought is investigated with a plant C-hydraulic model.
• Four phenological strategies are defined based on C uptake maximization and isohydry.
• These strategies and drought duration result in different growing-season C gains.
• Deciduous (resp. evergreen) strategies maximize C gain under long (short) droughts.
• Isohydric species sacrifice C gain by shedding leaves earlier than other strategies.

In most ecosystems, plants face periods with limited water availability, during which stomatal conductance is reduced to maintain hydration. However, prolonged dry spells might require more drastic strategies to conserve water, such as drought-deciduousness. If drought-related changes in leaf area are adaptive, it can be hypothesized that leaf area is optimized to maximize the growing-season carbon (C) gain. Different phenological strategies during drought have been proposed: (i) leaf area index (L) declines when net photosynthetic rates (Anet) reach zero to maintain a non-negative Anet; (ii) L adjusts to avoid water potentials with negative impacts on Anet; (iii) a constant leaf water potential is maintained (isohydric behavior); and (iv) leaf area remains unaltered (i.e., summer-evergreen leaf habit). However, whether these strategies are optimal in terms of growing season C gains has not been assessed. Here we consider these theories in a unified framework using the same set of equations to describe gas exchanges and water transport in the soil–plant–atmosphere continuum, and quantify the effect of the leaf phenological strategy on plant C gain over the entire growing season in different climates. Longer dry periods tend to favor drought-deciduous rather than summer-evergreen habit. Deciduous plants that allow leaf water potential to fluctuate (anisohydric) while preventing negative Anet assimilate more carbon than deciduous plants with fixed leaf water potentials (isohydric). Increased rooting depth allows evergreens to more effectively compete with drought-deciduous species. Moreover, increasing leaf nitrogen concentrations and thus photosynthetic capacity can be an effective acclimation strategy when dry periods are relatively short.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Advances in Water Resources - Volume 84, October 2015, Pages 37–51
نویسندگان
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