Climate change-driven extinctions of tree species affect forest functioning more than random extinctions
Climate change-driven extinctions of tree species affect forest functioning more than random extinctions
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DOI：
10.1111/ddi.12744
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发表时间：
2018-07-01
影响因子：
4.6
通讯作者：
Morin, Xavier
中科院分区：
文献类型：
--
作者：
Garcia-Valdes, Raul;Bugmann, Harald;Morin, Xavier
目的：气候变化不仅通过改变光合作用和生长季节长度等直接生理效应影响森林功能，而且还通过间接影响与物种灭绝和定居有关的群落组成。与直接影响相比，对这种间接影响的研究仍然很少。生物多样性-生态系统功能(BEF)研究通常通过随机消除物种来检查物种丧失的影响。然而，气候变化造成的物种灭绝将取决于物种对新环境条件的脆弱性，因此以特定的、非随机的顺序发生。在这里，我们根据树种对气候变化的脆弱性来评估连续树种灭绝是否会对森林功能产生不同于随机物种丧失的影响。地点：中欧气候条件梯度上的11个温带森林。方法：我们用森林演替模型模拟树木群落动态，研究物种丧失对群落地上生物量、生产力和时间稳定性的影响。根据(2)树种不能在较温暖的气候下被招募或(3)在较干燥的条件下增加死亡率，(1)随机地将树种从本地池中移走。结果：结果表明，非随机的物种损失(即基于它们对更温暖或更干燥条件的脆弱性)改变森林功能的速度和方向与随机的物种损失不同。此外，定向灭绝与随机灭绝不同，它在物种丧失过程中触发了临界点，森林功能受到了强烈影响。这些临界点发生在位于最寒冷地区的森林较少灭绝之后，那里的生态系统功能依赖于较少的物种。主要结论：我们表明，物种以确定性和机械动机的顺序灭绝，在这种情况下，物种对气候变化的脆弱性，加强了多样性对生态系统功能的选择作用。BEF的研究利用随机灭绝来探索物种丧失对生态系统功能的影响，因此可能低估了在气候变化等方向性力量的驱动下生物多样性丧失的潜在影响。
Aim: Climate change affects forest functioning not only through direct physiological effects such as modifying photosynthesis and growing season lengths, but also through indirect effects on community composition related to species extinctions and colonizations. Such indirect effects remain poorly explored in comparison with the direct ones. Biodiversity-ecosystem functioning (BEF) studies commonly examine the effects of species loss by eliminating species randomly. However, species extinctions caused by climate change will depend on the species' vulnerability to the new environmental conditions, thus occurring in a specific, non-random order. Here, we evaluated whether successive tree species extinctions, according to their vulnerability to climate change, impact forest functions differently than random species losses.Location: Eleven temperate forests across a gradient of climatic conditions in central Europe.Methods: We simulated tree community dynamics with a forest succession model to study the impact of species loss on the communities' aboveground biomass, productivity and temporal stability. Tree species were removed from the local pool (1) randomly, and according to (2) their inability to be recruited under a warmer climate or (3) their increased mortality under drier conditions.Results: Results showed that non-random species loss (i.e., based on their vulnerability to warmer or drier conditions) changed forest functioning at a different rate, and sometimes direction, than random species loss. Furthermore, directed extinctions, unlike random, triggered tipping points along the species loss process where forest functions were strongly impacted. These tipping points occurred after fewer extinctions in forests located in the coldest areas, where ecosystem functioning relies on fewer species.Main conclusions: We showed that the extinction of species in a deterministic and mechanistically motivated order, in this case the species vulnerability to climate change, strengthens the selection effect of diversity on ecosystem functioning. BEF studies exploring the impact of species loss on ecosystem functioning using random extinctions thus possibly underestimate the potential effect of biodiversity loss when driven by a directional force, such as climate change.