Plant species, temperature, and bedrock affect net methane flux out of grassland and forest soils

Nadine Praeg,Paul Illmer,Andreas O Wagner

doi:10.1007/s11104-016-2993-z

Abstract

AimsThe objectives of this study were to investigate the influence of plants on net methane flux from forest and grassland soils depending on bedrock, temperature, and plant species, and to determine the abundance of methanogenic and methanotrophic microorganisms.MethodsLab-scale gas measurements with forest and grassland soils and different site-specific plants were performed. Next-generation sequencing was conducted to characterize the archaeal community structure and the abundance of methanotrophic bacteria was determined via quantitative PCR.ResultsForest and grassland soils had a high potential to consume methane under ambient conditions. Irrespective of bedrock and plant species, a highly significant influence of temperature was established. The studied site-specific grassland plants Plantago lanceolata and Poa pratensis significantly increased methane balance with varying extent depending on temperature. In contrast, the studied forest plants Picea abies and especially Larix decidua significantly boosted methane consumption. The flux measurements pointed to higher net methane consumption rates on limestone compared to siliceous bedrock. The proportion of Euryarchaeota -including methanogens- increased in rhizosphere soil of grassland plants compared to bulk soil whereas methanotrophic abundances did not differ between bulk and rhizosphere soil.ConclusionsResults highlight that the methane fluxes in uplands soils are altered depending on plant species, temperature, and vegetation type and emphasize the need to better resolve the influence of plants on the methane cycle and the involved microorganisms.

Highlights

Methane (CH4) is an important greenhouse gas and its concentration in the atmosphere has increased from 0.7 ppm in pre-industrial times to 1.8 ppm at the moment (Dlugokencky et al 1998; Kirschke et al 2013)
At 25 °C ambient CH4 concentration decreased below detection level (0.1 ppm) within 48 h, the most pronounced CH4 net consumption was detected at 25 °C followed by 37 and 10 °C (Fig. 1)
We examined the impact of (1) temperature, (2) bedrock, (3) vegetation type, and (4) plants on net methane flux of upland soils

Summary

Introduction

Methane (CH4) is an important greenhouse gas and its concentration in the atmosphere has increased from 0.7 ppm in pre-industrial times to 1.8 ppm at the moment (Dlugokencky et al 1998; Kirschke et al 2013). Despite this low concentration, its contribution to climate warming is approximately 20 %, as the absorption of infrared radiation is about 20 to 30 times stronger than of CO2 (Milich 1999; Ottow 2011; Stiehl-Braun et al 2011). Most of the methane from natural sources originates from biological processes due to the activities of methanogenic Archaea. Recent studies revealed that various methanogens, especially Methanosarcina and Methanocella, can tolerate oxygen exposure but the underlying processes for this tolerance are still not well understood (Angel et al 2011)

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Conclusion