Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK.
School of Natural Sciences, Department of Biological Sciences, Keimyung University, Taegu, 42601, Republic of Korea.
Sci Rep. 2020 Dec 8;10(1):21419. doi: 10.1038/s41598-020-78413-z.
Little is known of the earliest stages of soil biota development of volcanic ash, and how rapidly it can proceed. We investigated the potential for soil biota development during the first 3 years, using outdoor mesocosms of sterile, freshly fallen volcanic ash from the Sakurajima volcano, Japan. Mesocosms were positioned in a range of climates across Japan and compared over 3 years, against the developed soils of surrounding natural ecosystems. DNA was extracted from mesocosms and community composition assessed using 16S rRNA gene sequences. Metagenome sequences were obtained using shotgun metagenome sequencing. While at 12 months there was insufficient DNA for sequencing, by 24 months and 36 months, the ash-soil metagenomes already showed a similar diversity of functional genes to the developed soils, with a similar range of functions. In a surprising contrast with our hypotheses, we found that the developing ash-soil community already showed a similar gene function diversity, phylum diversity and overall relative abundances of kingdoms of life when compared to developed forest soils. The ash mesocosms also did not show any increased relative abundance of genes associated with autotrophy (rbc, coxL), nor increased relative abundance of genes that are associated with acquisition of nutrients from abiotic sources (nifH). Although gene identities and taxonomic affinities in the developing ash-soils are to some extent distinct from the natural vegetation soils, it is surprising that so many of the key components of a soil community develop already by the 24-month stage. In this system, however, rapid development may be facilitated by the relatively moderate pH of the Sakurajima ash, proximity of our mesocosms to propagule sources, and the rapid establishment of a productive bryophyte and lichen layer on the surface. Ash from other volcanoes richer in acids or more distant from propagule sources could show a different pattern and slower soil biota development.
关于火山灰土壤生物区系发展的最早阶段，以及它能多快发展，人们知之甚少。我们使用来自日本樱岛火山的新鲜落下的无菌火山灰户外中规模培养皿，研究了前 3 年内土壤生物区系发展的潜力。中规模培养皿被放置在日本各地不同的气候中，并与周围自然生态系统中已发育的土壤进行了 3 年的比较。从中规模培养皿中提取 DNA，并使用 16S rRNA 基因序列评估群落组成。使用鸟枪法宏基因组测序获得宏基因组序列。虽然在 12 个月时，用于测序的 DNA 不足，但在 24 个月和 36 个月时，灰土壤宏基因组已经显示出与已发育土壤相似的功能基因多样性，功能范围相似。与我们的假设形成惊人对比的是，与已发育的森林土壤相比，我们发现正在发育的灰土壤群落已经显示出相似的基因功能多样性、门多样性和生命王国的整体相对丰度。灰土壤中规模培养皿也没有显示出任何与自养（rbc、coxL）相关的基因相对丰度增加，也没有显示出与从非生物来源获取营养相关的基因相对丰度增加（nifH）。尽管发育中的灰土壤中的基因身份和分类群亲和力在某种程度上与自然植被土壤不同，但令人惊讶的是，到 24 个月时，土壤群落的许多关键组成部分已经发育。然而，在这个系统中，快速发展可能是由于樱岛灰的相对适中的 pH 值、我们的中规模培养皿与繁殖体来源的接近以及表面上迅速建立的多产苔藓和地衣层促成的。来自其他富酸或离繁殖体来源更远的火山的灰可能会表现出不同的模式和更慢的土壤生物区系发展。
