Borruso Luigimaria, Bani Alessia, Pioli Silvia, Ventura Maurizio, Panzacchi Pietro, Antonielli Livio, Giammarchi Francesco, Polo Andrea, Tonon Giustino, Brusetti Lorenzo
Department of Science and Technology, Free University of Bozen-Bolzano, Bolzano, Italy.
School of Life Sciences, University of Essex Colchester Campus, Essex, United Kingdom.
Front Microbiol. 2021 Apr 16;12:633535. doi: 10.3389/fmicb.2021.633535. eCollection 2021.
The amount of nitrogen (N) deposition onto forests has globally increased and is expected to double by 2050, mostly because of fertilizer production and fossil fuel burning. Several studies have already investigated the effects of N depositions in forest soils, highlighting negative consequences on plant biodiversity and the associated biota. Nevertheless, the impact of N aerial inputs deposited directly on the tree canopy is still unexplored. This study aimed to investigate the influence of increased N deposition on the leaf-associated fungal and bacterial communities in a temperate forest dominated by Sessile oak [ (Matt.) Liebl.]. The study area was located in the Monticolo forest (South Tyrol, Italy), where an ecosystem experiment simulating an increased N deposition has been established. The results highlighted that N deposition affected the fungal beta-diversity and bacterial alpha-diversity without affecting leaf total N and C contents. We found several indicator genera of both fertilized and natural conditions within bacteria and fungi, suggesting a highly specific response to altered N inputs. Moreover, we found an increase of symbiotrophic fungi in N-treated, samples which are commonly represented by lichen-forming mycobionts. Overall, our results indicated that N-deposition, by increasing the level of bioavailable nutrients in leaves, could directly influence the bacterial and fungal community diversity.
全球范围内，森林的氮（N）沉降量有所增加，预计到2050年将翻倍，这主要是由于肥料生产和化石燃料燃烧。已有多项研究调查了氮沉降对森林土壤的影响，强调了其对植物生物多样性及相关生物群的负面影响。然而，直接沉积在树冠上的大气氮输入的影响仍未得到探索。本研究旨在调查氮沉降增加对以无梗花栎[（Matt.）Liebl.]为主的温带森林中与叶片相关的真菌和细菌群落的影响。研究区域位于蒙蒂科洛森林（意大利南蒂罗尔），那里已建立了一个模拟氮沉降增加的生态系统实验。结果表明，氮沉降影响了真菌的β多样性和细菌的α多样性，但未影响叶片的总氮和碳含量。我们在细菌和真菌中发现了几个施肥和自然条件下均有的指示属，这表明对氮输入变化有高度特异性的反应。此外，我们发现经过氮处理的样本中共生营养真菌增加，这些真菌通常由形成地衣的菌共生体代表。总体而言，我们的结果表明，氮沉降通过增加叶片中生物可利用养分的水平，可能直接影响细菌和真菌群落的多样性。
