Natural disturbance regimes in forest ecosystems are being rapidly modified by anthropogenic pressures, including silvicultural practices and climate change. Australian forests dominated by mountain ash (Eucalyptus regnans) are critically endangered, with wildfires and clearfell logging predicted to cause ecosystem collapse within the next 50 years. To investigate the influence of disturbance on patterns and extent of genetic diversity in mountain ash, we compare replicated sites with three different disturbance histories (undisturbed, burnt, and logged). We employ genetic analysis at five chloroplast microsatellite loci and 2866 nuclear single-nucleotide polymorphisms (SNPs) to estimate within- and among- population genetic diversity, and assess the extent of fine-scale spatial genetic structure among individuals, for the three disturbance treatments. Consistent with the expectation of extensive pollen dispersal but limited seed dispersal, we detected low levels of genetic differentiation at nuclear SNPs (F_ST = 0.067), and very high levels of differentiation at cpDNA microsatellites (F_ST = 0.751). While differences among treatments at nuclear SNPs were small, we found stronger spatial genetic structure in the undisturbed treatment, higher levels of genetic differentiation in the logged treatment and greater partitioning of genetic diversity among logged sites. Analysis of cpDNA revealed significantly higher levels of total and within-site genetic diversity in the logged treatment than the burnt or undisturbed treatments, with haplotypes entering the system via the use of non-local seed in the regeneration process. We suggest that artificial regeneration activities should utilise a greater number of maternal parents, which could be achieved via variable retention harvesting or utilising a regional admixture provenancing approach.

森林生态系统中的自然扰动制度正受到人为压力（包括造林方式和气候变化）的迅速改变。以山灰为主的澳大利亚森林（桉树）处于极度濒危的状态，预计在接下来的50年之内，山火和砍伐森林将导致生态系统崩溃。为了调查干扰对山灰中遗传多样性的模式和程度的影响，我们比较了三种不同干扰历史（未受干扰，被烧毁和被记录）的复制地点。我们对五个叶绿体微卫星基因座和2866个核单核苷酸多态性（SNP）进行了遗传分析，以估计种群内和种群间的遗传多样性，并评估了这三种干扰治疗方法中个体之间精细尺度空间遗传结构的程度。与花粉广泛散布的预期一致，但种子散布受到限制，我们在核SNP处检测到低水平的遗传分化（F _ST = 0.067），并且cpDNA微卫星的分化水平很高（F _ST = 0.751）。尽管核单核苷酸多态性的处理之间的差异很小，但我们发现未受干扰的处理具有更强的空间遗传结构，测井处理中的遗传分化水平更高，并且测井部位之间的遗传多样性分配更大。对cpDNA的分析表明，伐木处理后的总和现场遗传多样性水平明显高于烧录或未扰动处理，且单倍型通过在再生过程中使用非本地种子进入系统。我们建议人工再生活动应利用更多的父母，这可以通过可变保留收获或利用区域混合种源来实现。