1. Plants minimize fitness losses through grazing by three fundamental strategies: tolerance, avoidance and escape. Annual species have been traditionally assumed to escape grazing through their short life cycle and seed dormancy; however, their grazing response strategies remain almost unexplored. How traits and their coordination affect species' grazing responses, and whether the generalized grazing model, which posits convergent filtering by grazing and drought, is applicable to this ecologically and economically important species group thus remain unclear.
2. We used a trait-based approach to evaluate grazing response strategies of winter annuals from the Middle East. Across 23 species, we examined the coordination of 16 traits hypothesized to be relevant for grazing responses, and linked them to species' fecundity responses, as proxy for fitness responses, to simulated grazing in controlled conditions, to species' abundance responses to grazing in the field and to species' distribution along a large-scale rainfall gradient.
3. Winter annuals exhibited both grazing escape and to a lesser extent tolerance indicated by (a) independent coordination of escape and tolerance traits, and (b) maintenance of higher fecundity in species with more pronounced escape or tolerance traits under simulated grazing. In the natural habitat, species with a more pronounced escape but not tolerance strategy maintained higher abundance under grazing in dry habitats, indicating convergent favouring of escape by both grazing and drought. However, this finding at the local scale was not mirrored by a strategy shift along a large-scale rainfall gradient.
4. Synthesis. The convergent favouring of escape traits by grazing and drought in annuals is consistent with the generalized grazing model. This model, which has been developed for perennials based on the avoidance strategy, can thus be extended to annuals based on escape, a finding that should facilitate projecting consequences of global change in drylands dominated by annuals.

中文翻译：

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评估冬季一年生植物的放牧响应策略：一种多特征方法

1. 植物通过三种基本策略通过放牧来最大限度地减少适应性损失：容忍、回避和逃避。传统上认为，一年生物种由于生命周期短和种子休眠而逃避放牧；然而，他们的放牧反应策略几乎仍未得到探索。性状及其协调如何影响物种的放牧反应，以及假设通过放牧和干旱进行收敛过滤的广义放牧模型是否适用于这一具有生态和经济重要性的物种群，因此尚不清楚。
2. 我们使用基于特征的方法来评估来自中东的冬季一年生植物的放牧响应策略。在 23 个物种中，我们检查了 16 个假设与放牧反应相关的性状的协调，并将它们与物种的繁殖力反应（作为适应度反应的代表）、受控条件下的模拟放牧、物种对放牧的丰度反应联系起来。场和物种沿大尺度降雨梯度的分布。
3. 冬季一年生植物表现出放牧逃逸和较小程度的耐受性，这表明（a）逃逸和耐受性状的独立协调，以及（b）在模拟放牧下具有更明显逃逸或耐受性状的物种保持较高的繁殖力。在自然栖息地，具有更明显的逃逸而不是耐受策略的物种在干旱栖息地的放牧下保持较高的丰度，表明放牧和干旱都倾向于逃逸。然而，在局部尺度上的这一发现并没有被沿大尺度降雨梯度的战略转变所反映。
4. 合成。一年生放牧和干旱对逃逸性状的趋同偏好与广义放牧模型一致。这种基于回避策略为多年生植物开发的模型因此可以扩展到基于逃逸的一年生植物，这一发现应该有助于预测以一年生植物为主的旱地全球变化的后果。