Legacy attributes from land-use history have lingering effects on soil and its below-ground components undergoing succession that has important consequences for regenerating tropical secondary forests. Yet, even landscapes of similar origins with analogous land-use histories have exhibited differing routes of forest recovery with different outcomes. There is increasing evidence that tree species-generated soil microbial heterogeneity is an important factor in facilitating regeneration, particularly nitrogen (N)-fixing tree species. However, it is unclear how land-use history influences the soil microbiome of important N-fixing plants developing under these conditions; at different life stages of N-fixing plant development; and how this compares to a primary forest. We examined differences in composition of the soil bacterial and fungal communities and their determinants (i.e. soil environmental factors) associated with large-, medium-, and small-sized Pentaclethra macroloba trees in a primary forest and in a 23-year-old secondary forest with contrasting land-use histories. We show that as Pentaclethra increases in size (and/or age), the soil microbiome associated with Pentaclethra also changes, and that these soil microbiomes can become similar even when developed in soils of contrasting land-use histories. We found that soil NH4+ and NO3− explained 61% of the variation in the soil bacterial community composition of small trees between the primary and secondary forest. This highlights the importance of inorganic N during tree soil microbiome development in contrasting land-use history of soils. Our findings suggest that legacy effects on may be mediated through size (and/or age) of Pentaclethra and its associated soil microbiome.

中文翻译：

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Pentaclethra macroloba 的土壤微生物组在不同树木大小和对比土地利用历史中的差异

土地利用历史的遗产属性对土壤及其地下组成部分具有持续影响，对热带次生林的再生具有重要影响。然而，即使是具有相似土地利用历史的相似起源的景观，也表现出不同的森林恢复路线和不同的结果。越来越多的证据表明，树种产生的土壤微生物异质性是促进再生的重要因素，尤其是固氮 (N) 树种。然而，尚不清楚土地利用历史如何影响在这些条件下发育的重要固氮植物的土壤微生物组。在固氮植物发育的不同生命阶段；以及这与原始森林相比如何。我们研究了与原生林和 23 年生次生林中大、中、小型五角星树相关的土壤细菌和真菌群落组成及其决定因素（即土壤环境因素）的差异与对比的土地使用历史。我们表明，随着 Pentaclethra 大小（和/或年龄）的增加，与 Pentaclethra 相关的土壤微生物群也会发生变化，即使在土地利用历史截然不同的土壤中发育时，这些土壤微生物群也会变得相似。我们发现土壤 NH4+ 和 NO3− 解释了原生林和次生林之间小树土壤细菌群落组成变化的 61%。这突出了无机氮在树木土壤微生物群发展过程中对比土壤土地利用历史的重要性。