Changes in vegetative and reproductive phenology rank among the most obvious plant responses to climate change. These responses vary broadly among species, but it is largely unknown whether they are mediated by functional attributes, such as size or foliar traits. Using a manipulative experiment conducted over two growing seasons, we evaluated the responses in reproductive phenology and output of 14 Mediterranean semiarid species belonging to three functional groups (grasses, nitrogen-fixing legumes and forbs) to a ~3°C increase in temperature, and assessed how leaf and size traits influenced them. Overall, warming advanced flowering and fruiting phenology, extended the duration of flowering and reduced the production of flowers and fruits. The observed reduction in flower and fruit production with warming was likely related to the decrease in soil moisture promoted by this treatment. Phenological responses to warming did not vary among functional groups, albeit forbs had an earlier reproductive phenology than legumes and grasses. Larger species with high leaf area, as well as those with small specific leaf area, had an earlier flowering and a longer flowering duration. The effects of warming on plant size and leaf traits were related to those on reproductive phenology and reproductive output. Species that decreased their leaf area under warming advanced more the onset of flowering, while those that increased their vegetative height produced more flowers. Our results advance our understanding of the phenological responses to warming of Mediterranean semiarid species, and highlight the key role of traits such as plant size and leaf area as determinants of such responses.

中文翻译：

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植物大小和叶面积影响半干旱地中海物种对变暖的物候和生殖反应。


营养和生殖物候的变化是植物对气候变化最明显的反应之一。这些反应在物种之间差异很大，但很大程度上未知它们是否是由功能属性（例如大小或叶性状）介导的。通过在两个生长季节进行的操作性实验，我们评估了属于三个功能组（禾本科、固氮豆科植物和禾本科植物）的 14 种地中海半干旱物种的生殖物候和产量对温度升高约 3°C 的反应，以及评估了叶子和大小特征如何影响它们。总体而言，变暖促进了花果物候，延长了花期，减少了花果产量。观察到的花卉和水果产量随变暖而减少可能与该处理促进的土壤湿度下降有关。尽管非禾本科植物比豆科植物和禾本科植物具有更早的繁殖物候，但不同功能群体对变暖的物候反应没有差异。叶面积较大的物种以及比叶面积较小的物种开花较早，花期较长。变暖对植物大小和叶片性状的影响与对生殖物候和生殖产量的影响有关。在气候变暖的情况下，叶面积减少的物种会提前更多的开花时间，而那些增加营养高度的物种会产生更多的花朵。我们的研究结果增进了我们对地中海半干旱物种对变暖的物候反应的理解，并强调了植物大小和叶面积等性状作为此类反应的决定因素的关键作用。