Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK.
Institute of Marine Sciences, University of California, Santa Cruz, CA, 95060, USA.
Ecol Lett. 2021 May;24(5):1007-1017. doi: 10.1111/ele.13719. Epub 2021 Mar 10.
Global change is shifting disturbance regimes that may rapidly change ecosystems, sometimes causing ecosystems to shift between states. Interactions between disturbances such as fire and disease could have especially severe effects, but experimental tests of multi-decadal changes in disturbance regimes are rare. Here, we surveyed vegetation for 35 years in a 54-year fire frequency experiment in a temperate oak savanna-forest ecotone that experienced a recent outbreak of oak wilt. Different fire regimes determined whether plots were savanna or forest by regulating tree abundance (r = 0.70), but disease rapidly reversed the effect of fire exclusion, increasing mortality by 765% in unburned forests, but causing relatively minor changes in frequently burned savannas. Model simulations demonstrated that disease caused unburned forests to transition towards a unique woodland that was prone to transition to savanna if fire was reintroduced. Consequently, disease-fire interactions could shift ecosystem resilience and biome boundaries as pathogen distributions change.
全球变化正在改变干扰格局，这可能会使生态系统迅速发生变化，有时甚至会导致生态系统在不同状态之间发生转变。火灾和疾病等干扰因素之间的相互作用可能会产生特别严重的影响，但对干扰机制数十年变化的实验测试却很少见。在这里，我们在一个经历了最近橡树萎蔫病爆发的温带橡树稀树草原-森林交错带的 54 年火灾频率实验中进行了 35 年的植被调查。不同的火灾机制通过调节树木丰度（r = 0.70）来决定斑块是稀树草原还是森林，但疾病迅速逆转了火灾排除的影响，使未燃烧森林的死亡率增加了 765%，而在频繁燃烧的稀树草原中则引起相对较小的变化。模型模拟表明，疾病使未燃烧的森林向一种独特的林地过渡，如果引入火灾，这种林地很容易向稀树草原过渡。因此，随着病原体分布的变化，疾病与火灾的相互作用可能会改变生态系统的恢复力和生物群落的边界。
