Tree plantation systems influence nitrogen retention and the abundance of nitrogen functional genes in the Solomon Islands

Frederique Reverchon; Shahla Hosseini Bai; Xian Liu; Timothy J Blumfield

doi:10.3389/fmicb.2015.01439

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Tree plantation systems influence nitrogen retention and the abundance of nitrogen functional genes in the Solomon Islands

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Tree plantation systems influence nitrogen retention and the abundance of nitrogen functional genes in the Solomon Islands

Frederique Reverchon, Shahla Hosseini Bai, Xian Liu and Timothy J Blumfield

Frontiers in Microbiology, Vol.6, 1439

2015

DOI: https://doi.org/10.3389/fmicb.2015.01439

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Abstract

tectona grandis

flueggea flexuosa

mixed species plantations

δ15N

tropical soil

qPCR

Tree mono-plantations are susceptible to soil nutrient impoverishment and mixed species plantations have been proposed as a way of maintaining soil fertility while enhancing biodiversity. In the Solomon Islands, mixed species plantations where teak (Tectona grandis) is inter-planted with a local tree species (Flueggea flexuosa) have been used as an alternative to teak mono-plantations and are expected to increase soil microbial diversity and modify microbial biogeochemical processes. In this study, we quantified the abundance of microbial functional genes involved in the nitrogen (N) cycle from soil samples collected in teak, flueggea, and mixed species plantations. Furthermore, we measured soil properties such as pH, total carbon (C) and total N, stable N isotope composition (δ15N), and inorganic N pools. Soil pH and δ15N were higher under teak than under flueggea, which indicates that intercropping teak with flueggea may decrease bacterial activities and potential N losses. Higher C:N ratios were found under mixed species plantations than those under teak, suggesting an enhancement of N immobilisation that would help preventing fast N losses. However, inorganic N pools remained unaffected by plant cover. Inter-planting teak with flueggea in mixed species plantations generally increased the relative abundance of denitrification genes and promoted the enrichment of nosZ-harboring denitrifiers. However, it reduced the abundance of bacterial amoA (ammonia monooxygenase) genes compared to teak mono-plantations. The abundance of most denitrification genes correlated with soil total N and C:N ratio, while bacterial and archeal nitrification genes correlated positively with soil NH4+ concentrations. Altogether, these results show that the abundance of bacterial N-cycling functional guilds vary under teak and under mixed species plantations, and that inter-planting teak with flueggea may potentially alleviate N losses associated with nitrification and denitrification and favour N retention. Mixed plantations could also allow an increase in soil C and N stocks without losing the source of income that teak trees represent for local communities.

Details

Title: Tree plantation systems influence nitrogen retention and the abundance of nitrogen functional genes in the Solomon Islands
Authors: Frederique Reverchon (Author) - Griffith University
Shahla Hosseini Bai (Author) - University of the Sunshine Coast - Faculty of Science, Health, Education and Engineering
Xian Liu (Author) - Griffith University
Timothy J Blumfield (Author) - Griffith University
Publication details: Frontiers in Microbiology, Vol.6, 1439; 12
Publisher: Frontiers Research Foundation
Date published: 2015
DOI: 10.3389/fmicb.2015.01439
ISSN: 1664-302X
Copyright note: Copyright © 2015 Reverchon, Hosseini Bai, Liu and Blumfield. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Organisation Unit: School of Science and Engineering - Legacy; University of the Sunshine Coast, Queensland
Language: English
Record Identifier: 99449947802621
Output Type: Journal article