Vegetation at ecotone transitions between open and forested areas is often heavily affected by two key processes: climate change and management of large herbivore densities. These both drive woody plant state shifts, determining the location and the nature of the limit between open and tree or shrub‐dominated landscapes. In order to adapt management to prevailing and future climate, we need to understand how browsing and climatic factors together affect the growth of plants at biome borders. To disentangle herbivory and climate effects, we combined long‐term tree growth monitoring and dendroecology to investigate woody plant growth under different temperatures and red deer (Cervus elaphus) herbivory pressures at forest–moorland ecotones in the Scottish highlands. Reforestation and deer densities are core and conflicting management concerns in the area, and there is an urgent need for additional knowledge. We found that deer herbivory and climate had significant and interactive effects on tree growth: in the presence of red deer, pine (Pinus sylvestris) growth responded more strongly to annual temperature than in the absence of deer, possibly reflecting differing plant–plant competition and facilitation conditions. As expected, pine growth was negatively related to deer density and positively to temperature. However, at the tree population level, warming decreased growth when more than 60% of shoots were browsed. Heather (Calluna vulgaris) growth was negatively related to temperature and the direction of the response to deer switched from negative to positive when mean annual temperatures fell below 6.0°C. In addition, our models allow estimates to be made of how woody plant growth responds under specific combinations of temperature and herbivory, and show how deer management can be adapted to predicted climatic changes in order to more effectively achieve reforestation goals. Our results support the hypothesis that temperature and herbivory have interactive effects on woody plant growth, and thus accounting for just one of these two factors is insufficient for understanding plant growth mechanics at biome transitions. Furthermore, we show that climate‐driven woody plant growth increases can be negated by herbivory.

中文翻译：

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食草和气候是木本植物生长的驱动力：鹿能减少变暖的影响吗？

开阔林区之间的过渡过渡带上的植被通常受到两个关键过程的严重影响：气候变化和大型草食动物密度的管理。这两者都推动了木本植物的状态转变，从而决定了开放和树木或灌木为主的景观之间界限的位置和性质。为了使管理适应当前和未来的气候，我们需要了解浏览和气候因素如何共同影响生物群落边界植物的生长。为了消除草食和气候影响，我们结合了长期树木生长监测和树状生态学，以研究不同温度和马鹿（鹿）下木本植物的生长。）苏格兰高地森林－荒地过渡带的食草压力。植树造林和鹿的密度是该地区的核心和相互冲突的管理问题，因此迫切需要更多的知识。我们发现，鹿的食草和气候对树木的生长具有显着的交互作用：在有马鹿的情况下，松树（Pinus sylvestris）的生长对年温度的响应要比在没有鹿的情况下更为强烈，这可能反映了不同的植物竞争和便利条件。正如预期的那样，松树的生长与鹿的密度呈负相关，而与温度呈正相关。但是，在树木种群水平上，当浏览超过60％的芽时，变暖会降低生长速度。希瑟（寻常的紧急电报）生长与温度呈负相关，当年平均温度降至6.0°C以下时，对鹿的响应方向从负变为正。此外，我们的模型还可以估算木本植物在特定温度和食草条件下的生长情况，并说明如何将鹿的管理方法适应预测的气候变化，从而更有效地实现造林目标。我们的结果支持以下假设：温度和草食对木本植物的生长具有相互作用的影响，因此，仅考虑这两个因素之一不足以理解生物群落转变时的植物生长机理。此外，我们表明，食草可以抵消气候驱动的木本植物生长的增加。