Foliar N Content Parallels Increasing Aridity in a Mediterranean-Saharan Transition Zone: Evidence From Regional and Global Trends

IF 3.4 2区环境科学与生态学 Q2 ECOLOGY

Journal of Biogeography Pub Date : 2024-10-19 DOI:10.1111/jbi.15027

Tomasz P. Wyka, Piotr Robakowski, Angel Romo, Adam Boratyński, Roma Żytkowiak, Jacek Oleksyn

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引用次数: 0

Abstract

Aim

Warm deserts are characterised by water shortages and high temperature extremes. A commonly reported adaptive strategy in such environments is maximisation of photosynthetic capacity, which allows plants to achieve positive carbon budgets by taking advantage of short periods of water availability and non-inhibitory temperatures. Considering the well-supported interspecific covariation between photosynthetic capacity and leaf N concentration, we tested the hypothesis that environmental aridity is related to an elevated leaf nitrogen content.

Location

53 locations in the transitional zone spanning the Mediterranean and the Sahara Desert in Morocco. The mean maximal temperature (T_max) within the area varied between 35.7°C and 43.5°C, and the mean annual precipitation (MAP) was between 12 and 246 mm.

Taxon

225 vascular species representative of local vegetation.

Methods

Leaf samples were collected along a regional aridity gradient and preserved in herbarium presses. The leaf mass per area (LMA) and N concentrations expressed on leaf mass (N_mass) and area (N_area) basis were determined. We also obtained LMA and N_mass values for 6711 species from a worldwide database for comparative analysis.

Results

Significant increases in mean LMA, N_mass and N_area accompanied the increase in T_max and the decrease in MAP in woody species and in non-graminoid herbs, but not in graminoids. Considering the overall aridity of our sampling area, we compared the N_mass values of Moroccan plants with those from a worldwide database. We found that at a common LMA, the Moroccan plants showed on average elevated N_mass relative to global values.

Main Conclusions

These two lines of evidence: regional gradient and global comparison confirm that hot deserts select for high leaf N content. This result suggests the direction of natural selection that will accompany future climate warming and habitat aridification.

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目的暖沙漠的特点是缺水和极端高温。在这种环境中，一种常见的适应策略是最大限度地提高光合作用能力，使植物能够利用短时间的水分供应和非抑制性温度实现正碳预算。考虑到光合作用能力与叶片氮浓度之间的种间协变关系已得到充分证实，我们检验了环境干旱与叶片氮含量升高有关的假设。地点 53 个地点位于摩洛哥横跨地中海和撒哈拉沙漠的过渡地带。该地区的平均最高温度（Tmax）介于 35.7°C 和 43.5°C 之间，平均年降水量（MAP）介于 12 毫米和 246 毫米之间。分类群 225 个维管束物种代表了当地的植被。方法沿地区干旱梯度采集叶片样本，并保存在标本馆的压片机中。测定了单位面积的叶片质量（LMA）以及以叶片质量（Nmass）和面积（Narea）表示的氮浓度。我们还从全球数据库中获得了 6711 个物种的 LMA 和 Nmass 值，以进行比较分析。结果在木本植物和非禾本科草本植物中，平均LMA、Nmass和Narea的显著增加伴随着Tmax的增加和MAP的降低，而在禾本科植物中则没有。考虑到我们取样地区的总体干旱程度，我们将摩洛哥植物的 Nmass 值与全球数据库中的数值进行了比较。我们发现，在一个共同的低海拔地区，摩洛哥植物的氮质量平均高于全球数值。主要结论区域梯度和全球比较这两个证据证实，炎热沙漠选择了高叶片氮含量。这一结果表明，未来气候变暖和生境干旱化将伴随着自然选择的方向。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Biogeography 环境科学-生态学

CiteScore

7.70

自引率

5.10%

发文量

203

审稿时长

2.2 months

期刊介绍： Papers dealing with all aspects of spatial, ecological and historical biogeography are considered for publication in Journal of Biogeography. The mission of the journal is to contribute to the growth and societal relevance of the discipline of biogeography through its role in the dissemination of biogeographical research.