In highly disturbed environments, clonality facilitates plant survival via resprouting after disturbance, resource sharing among interconnected stems and vegetative reproduction. These traits likely contribute to the encroachment of deep-rooted clonal shrubs in tallgrass prairie. Clonal shrubs have access to deep soil water and are typically thought of as relatively insensitive to environmental variability. However, how leaf physiological traits differ among stems within individual clonal shrubs (hereafter ‘intra-clonal’) in response to extreme environmental variation (i.e. drought or fire) is unclear. Accounting for intra-clonal differences among stems in response to disturbance is needed to more accurately parameterize models that predict the effects of shrub encroachment on ecosystem processes. We assessed intra-clonal leaf-level physiology of the most dominant encroaching shrub in Kansas tallgrass prairie, Cornus drummondii, in response to precipitation and fire. We compared leaf gas exchange rates from the periphery to centre within shrub clones during a wet (2015) and extremely dry (2018) year. We also compared leaf physiology between recently burned shrubs (resprouts) with unburned shrubs in 2018. Resprouts had higher gas exchange rates and leaf nitrogen content than unburned shrubs, suggesting increased rates of carbon gain can contribute to recovery after fire. In areas recently burned, resprouts had higher gas exchange rates in the centre of the shrub than the periphery. In unburned areas, leaf physiology remained constant across the growing season within clonal shrubs (2015 and 2018). Results suggest single measurements within a shrub are likely sufficient to parameterize models to understand the effects of shrub encroachment on ecosystem carbon and water cycles, but model parameterization may require additional complexity in the context of fire.

中文翻译：

---

在克隆整合的灌木中，叶片生理的时空差异与火有关，而不是干旱

在高度干扰的环境中，克隆性通过干扰后的重新萌芽、相互连接的茎之间的资源共享和无性繁殖来促进植物的生存。这些特征可能导致高草草原中根深蒂固的克隆灌木的侵占。克隆灌木可以接触深层土壤水，通常被认为对环境变化相对不敏感。然而，对于极端环境变化（即干旱或火灾）的反应，单个克隆灌木（以下简称“克隆内”）的茎之间的叶片生理特征如何不同尚不清楚。需要考虑响应干扰的茎之间的克隆内差异，以更准确地参数化预测灌木侵占对生态系统过程影响的模型。我们评估了堪萨斯高草草原中最主要的侵入灌木 Cornus drummondii 对降水和火灾的反应的克隆内叶水平生理学。我们比较了在潮湿（2015 年）和极度干燥（2018 年）年份中灌木无性系从外围到中心的叶片气体交换率。我们还在 2018 年比较了最近燃烧的灌木（新芽）和未燃烧的灌木之间的叶片生理学。新芽的气体交换率和叶片氮含量高于未燃烧的灌木，这表明碳增加率有助于火灾后的恢复。在最近被烧毁的地区，新芽在灌木中心的气体交换率高于外围。在未烧毁的地区，无性系灌木的整个生长季节（2015 年和 2018 年）的叶片生理保持不变。