Spore heat resistance plays an important role in disturbance-mediated assemblage shift of ectomycorrhizal fungi colonizing Pinus muricata seedlings
Spore heat resistance plays an important role in disturbance-mediated assemblage shift of ectomycorrhizal fungi colonizing Pinus muricata seedlings
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DOI：
10.1111/j.1365-2745.2009.01489.x
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发表时间：
2009-05-01
影响因子：
5.5
通讯作者：
Bruns, Thomas D.
中科院分区：
文献类型：
--
作者：
Peay, Kabir G.;Garbelotto, Matteo;Bruns, Thomas D.
非生物干扰在确定许多生态系统的组合结构和维持物种丰富度方面发挥着重要作用。干扰事件很复杂，通常会同时影响多个环境参数并导致生物量的选择性去除。因此，观察研究常常无法阐明干扰改变装配结构的主要机制。对于微生物系统来说尤其如此，其中生物量的减少或竞争优势的消除在视觉上并不明显。火灾是松科森林的主要干扰，其特征是外生菌根真菌根联合体。为了确定这种干扰影响外生菌根群落的具体机制，我们通过在暴露于土壤加热和灰添加的因子组合的田间土壤中种植幼苗来实验模拟火灾的影响。然后使用 DNA 序列从幼苗根中鉴定出每个处理中的外生菌根定殖者。土壤加热和灰分添加都会导致土壤化学环境的变化，并改变幼苗根上发现的真菌组合。土壤加热对外生菌根组装的影响最为明显，这导致了一些具有粗鲁生活史策略的类群的总体简化和优势地位的增加。我们还进行了一项后续实验，看看外生菌根孢子的选择性死亡是否可能导致这些模式。热暴露对所有测试的物种都有强烈的负面影响。然而，对于在加热土壤中生长的幼苗丰度增加最多的物种来说，孢子耐热性最高。合成。火灾通过改变土壤化学和常驻生物的死亡率来改变地下群落。我们的结果表明，土壤加热和选择性死亡是决定火灾后外生菌根真菌组合结构的关键机制。这些干扰有利于竞争较差的物种，并可能有助于维持景观尺度上外生菌根组合的多样性。
Abiotic disturbance plays an important role in determining assemblage structure and maintaining species richness in many ecosystems. Disturbances events are complex, often affecting multiple environmental parameters simultaneously and causing selective removal of biomass. For this reason, observational studies often fail to elucidate the primary mechanism by which disturbance modifies assembly structure. This is particularly true of microbial systems where reduction in biomass or removal of competitive dominants is not visually obvious.Fire is a major disturbance in pinaceous forests, which are characterized by ectomycorrhizal fungal root associations. To determine the specific mechanisms through which this disturbance affects ectomycorrhizal communities, we experimentally simulated the effects of fire by growing seedlings in field soil exposed to factorial combinations of soil heating and ash addition. Ectomycorrhizal colonists in each of the treatments were then identified from seedling roots using DNA sequences.Both soil heating and ash addition caused changes to the soil chemical environment and altered the fungal assemblages found on seedling roots. The effect on the ectomycorrhizal assembly was most pronounced from soil heating, which caused an overall simplification and increasing dominance by a few taxa with ruderal life-history strategies.We also conducted a follow-up experiment to see whether selective mortality of ectomycorrhizal spores might contribute to these patterns. Heat exposure had strong negative effects on all species tested. However, spore heat tolerance was highest for the species that showed the greatest increase in abundance on seedlings grown in heated soils.Synthesis. Fire alters below-ground communities through changes in soil chemistry and mortality of resident organisms. Our results show that soil heating and selective mortality are key mechanisms determining post-fire assemblage structure of ectomycorrhizal fungi. These disturbances favour competitively inferior species and may help maintain diversity of ectomycorrhizal assemblages at the landscape scale.