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What drives grassland‐forest boundaries? Assessing fire and frost effects on tree seedling survival and architecture
Ecology and Evolution ( IF 2.6 ) Pub Date : 2020-09-20 , DOI: 10.1002/ece3.6730 Monique Botha 1, 2 , Sally Archibald 1 , Michelle Greve 2
中文翻译:
是什么驱动草原与森林之间的界限?评估火灾和霜冻对树木幼苗存活和建筑的影响
更新日期:2020-10-12
Ecology and Evolution ( IF 2.6 ) Pub Date : 2020-09-20 , DOI: 10.1002/ece3.6730 Monique Botha 1, 2 , Sally Archibald 1 , Michelle Greve 2
Affiliation
- Fire and frost represent two major hurdles for the persistence of trees in open grassy biomes and have both been proposed as drivers of grassland‐forest boundaries in Africa.
- We assess the response of young tree seedlings, which represent a vulnerable stage in tree recruitment, to traumatic fire and frost disturbances.
- In a greenhouse experiment, we investigated how seedling traits predicted survival and resprouting ability in response to fire versus frost; we characterized survival strategies of seedlings in response to the two disturbances, and we documented how the architecture of surviving seedlings is affected by fire versus frost injury.
- Survival rates were similar under both treatments. However, different species displayed different levels of sensitivity to fire and frost. Seedling survival was higher for older seedlings and seedlings with more basal leaves. Survivors of a fire event lost more biomass than the survivors of a frost event. However, the architecture of recovered fire‐ and frost‐treated seedlings was mostly similar. Seedlings that recovered from fire and frost treatments were often shorter than those that had not been exposed to any disturbance, with multiple thin branches, which may increase vulnerability to the next frost or fire event.
- Synthesis. Fire caused more severe aboveground damage compared with a single frost event, suggesting that fire is an important driver of tree distribution in these open grassland systems. However, the impact of repeated frost events may be equally severe and needs to be investigated. Also, woody species composition may be influenced by phenomena that affect the timing and frequency of seedling exposure to damage, as mortality was found to be dependent on seedling age. Therefore, changes in fire regime and climate are likely to result in changes in the composition and the structure of the woody components of these systems.
中文翻译:
是什么驱动草原与森林之间的界限?评估火灾和霜冻对树木幼苗存活和建筑的影响
- 火和霜冻是开放的草丛生物群落中树木持久性的两个主要障碍,并且都被认为是非洲草原-森林边界的驱动因素。
- 我们评估了幼树幼苗对创伤性火灾和霜冻干扰的响应,这是树木募集的脆弱阶段。
- 在温室实验中,我们调查了幼苗性状如何预测火灾和霜冻的存活率和发芽能力。我们描述了响应两种干扰的幼苗生存策略,并记录了火灾和霜冻伤害如何影响生存幼苗的结构。
- 两种治疗的存活率相似。但是,不同物种对火和霜的敏感性不同。较老的幼苗和基叶较多的幼苗的幼苗存活率更高。火灾事件的幸存者损失的生物量比霜冻事件的幸存者更多。但是,经过火种和霜冻处理的幼苗的结构基本相似。从火和霜处理中恢复的幼苗通常比没有受到任何干扰的幼苗短,并具有多个细枝,这可能增加对下一次霜或火事件的脆弱性。
- 综合。与单次霜冻事件相比,大火对地面的破坏更为严重,这表明在这些开放的草原系统中,大火是树木分布的重要驱动因素。但是,反复的霜冻事件可能同样严重,需要进行调查。同样,木本植物的成分可能受影响幼苗暴露于损害的时间和频率的现象的影响,因为发现死亡率取决于幼苗的年龄。因此,火灾状况和气候的变化很可能导致这些系统木质成分的组成和结构发生变化。