Grassland and savanna ecosystems, important for both livelihoods and biodiversity conservation, are strongly affected by ecosystem drivers such as herbivory, fire, and drought. Interactions among fire, herbivores and vegetation produce complex feedbacks in these ecosystems, but these have rarely been studied in the context of fuel continuity and resultant fire heterogeneity. We carried out 36 controlled burns within replicated experimental plots that had allowed differential access by wild and domestic large herbivores since 1995 in a savanna ecosystem in Kenya. Half of these were reburns of plots burned five years previously. We show here that the fine-scale spatial heterogeneity of fire was greater in plots a) previously burned, b) accessible to large herbivores, and especially c) these two in combination. An additional embedded experiment demonstrated that even small experimental burn-free patches can have strong positive effects on tree saplings, which experienced less damage during controlled burns and quicker post-fire recovery. This work highlights the importance of simultaneously examining the interactions between fire and herbivory on fuel heterogeneity, which can have important impacts on the growth of woody saplings in savanna grasslands.

中文翻译：

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长期食草和先前火灾对指定草地烧伤的细尺度异质性的协同作用

草原和热带稀树草原生态系统对生计和生物多样性保护都很重要，但受到食草、火灾和干旱等生态系统驱动因素的强烈影响。火、食草动物和植被之间的相互作用在这些生态系统中产生复杂的反馈，但很少在燃料连续性和由此产生的火异质性的背景下研究这些。自 1995 年以来，我们在重复的实验地块内进行了 36 次受控燃烧，这些地块允许野生和家养大型食草动物在肯尼亚的稀树草原生态系统中进行不同的访问。其中一半是五年前烧毁的地块的重新烧毁。我们在这里表明，在 a) 以前燃烧过的地块中，火的精细空间异质性更大，b) 大型食草动物可以进入，尤其是 c) 这两者的组合。一项额外的嵌入式实验表明，即使是小的实验性免烧补丁也可以对树苗产生强烈的积极影响，在受控燃烧期间受到的损害较小，火灾后恢复速度更快。这项工作强调了同时检查火和食草动物对燃料异质性的相互作用的重要性，这可能对稀树草原草原木本树苗的生长产生重要影响。