澳大利亚维多利亚州，降雨和计划火烧对褶唇贝母兰种群及其内生真菌的影响。
Changes in orchid populations and endophytic fungi with rainfall and prescribed burning in Pterostylis revoluta in Victoria, Australia.
机构信息
School of Science, RMIT University (Bundoora West Campus), Bundoora, VIC, Australia.
出版信息
Ann Bot. 2018 Feb 12;121(2):321-334. doi: 10.1093/aob/mcx164.
BACKGROUND AND AIMS
Wildfires are common in seasonally dry parts of the world with a Mediterranean climate. Prescribed burning is used to reduce fuel load and fire risk, but often without reliable information on its effects. This study investigated the effects of prescribed burns in different seasons on Pterostylis revoluta, an autumn-flowering Australian terrestrial orchid, and its orchid mycorrhizal fungi (OMFs) to find the least damaging season for a prescribed burn.
METHODS
Burns were conducted mid-season in spring and summer 2011 and autumn and winter 2012. Orchids were enumerated and measured during their flowering season in autumn 2011-2014 and mycorrhizal fungi were isolated before and after the burns in autumn 2011, 2012 and 2014. Micro-organisms isolated were characterized. DNA was extracted from the OMFs, and the internal transcribed spacer region was amplified by PCR. Amplicons were clustered by restriction fragment length polymorphism (RFLP), and representative amplicons were sequenced. OMF were tested for sensitivity to smoke water.
KEY RESULTS
The number of plants increased up to 4-fold and 90 % of plants became vegetative during this study. Isolation of mycorrhizal fungi increased and isolation of bacteria decreased. Before the burns, the main OMF isolated was unexpectedly Tulasnella calospora (Boud.) Juel. By 2014, after the burns, the expected Ceratobasidium sp. D.P. Rogers was the only OMF isolated in most burnt quadrats, whereas T. calospora was confined to a minority of unburnt 'control' and the 'spring burn' quadrats, which were also the only ones with flowering plants.
CONCLUSIONS
The decline in rainfall during 2010-2012 probably caused the switch from mainly flowering to mainly vegetative plants and the change in OMFs. Burning in spring to summer was less damaging to this orchid than burning in autumn to winter, which should be noted by authorities in fire management plans for fire-prone areas in which this orchid occurs.
背景和目的
野火在具有地中海气候的季节性干燥地区很常见。采用计划火烧来减少燃料负荷和火灾风险，但通常缺乏对其影响的可靠信息。本研究调查了不同季节的计划火烧对秋季开花的澳大利亚陆生兰花 Pterostylis revoluta 及其兰花菌根真菌 (OMF) 的影响，以找到对计划火烧最不具破坏性的季节。
方法
2011 年春季和夏季以及 2012 年秋季和冬季进行火烧。在 2011 年至 2014 年秋季开花期间对兰花进行计数和测量，并在 2011 年、2012 年和 2014 年秋季火烧前后分离菌根真菌。对分离出的微生物进行特征描述。从 OMF 中提取 DNA，通过 PCR 扩增内部转录间隔区。通过限制性片段长度多态性 (RFLP) 对扩增子进行聚类，并对代表性扩增子进行测序。测试 OMF 对烟雾水的敏感性。
主要结果
在本研究中，植物数量增加了 4 倍，90%的植物变成了营养生长。菌根真菌的分离增加，细菌的分离减少。在火烧之前，出乎意料地分离到主要的 OMF 是 Tulasnella calospora (Boud.) Juel。到 2014 年，经过火烧后，唯一在大多数火烧样方中分离到的 OMF 是 Ceratobasidium sp. D.P. Rogers，而 T. calospora 仅限于少数未燃烧的“对照”和“春季燃烧”样方，这些样方也是唯一有开花植物的样方。
结论
2010 年至 2012 年降雨量减少可能导致植物从主要开花转变为主要营养生长，以及 OMF 的变化。春季至夏季的火烧对这种兰花的破坏性小于秋季至冬季的火烧，这一点应该引起火灾管理计划当局的注意，这些计划是在发生这种兰花的火灾多发地区制定的。
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