Peat Properties, Dominant Vegetation Type and Microbial Community Structure in a Tropical Peatland

Abstract

Tropical peatlands are an important carbon store and source of greenhouse gases, but the microbial component, particularly community structure, remains poorly understood. While microbial communities vary between tropical peatland land uses, and with biogeochemical gradients, it is unclear if their structure varies at smaller spatial scales as has been established for a variety of peat properties. We assessed the abundances of PLFAs and GDGTs, two membrane spanning lipid biomarkers in bacteria and fungi, and bacteria and archaea, respectively, to characterise peat microbial communities under two dominant and contrasting plant species, Campnosperma panamensis (a broadleaved evergreen tree), and Raphia taedigera (a canopy palm), in a Panamanian tropical peatland. The plant communities supported similar microbial communities dominated by Gram negative bacteria (38.9-39.8%), with smaller but significant fungal and archaeal communities. The abundance of specific microbial groups, as well as the ratio of caldarchaeol:crenarchaeol, isoGDGT: brGDGTs and fungi:bacteria were linearly related to gravimetric moisture content, redox potential, pH and organic matter content indicating their role in regulating microbial community structure. These results suggest that tropical peatlands can exhibit significant variability in microbial community abundance even at small spatial scales, driven by both peat botanical origin and localised differences in specific peat properties.

Root oxygen mitigates methane fluxes in tropical peatlands

“…Phospholipid fatty acids (PLFAs) were extracted from peat samples following the Bligh and Dyer protocol (1959) and quantified via GC analysis. Detailed methods and PLFA designations are provided in supplementary information [24].…”

“…However, substantial CH 4 transport can occur through palm pneumatophores [40]. Consequently, the similar peat surface CH 4 fluxes between species, despite different dissolved oxygen inputs, is likely differing contributions of root transport of CH 4 , contrasting peat organic chemistry and rates of decomposition under alternating aerobic or anaerobic conditions [17], and variation in methanogenic and methanotrophic community structure and activity [24,41,42].…”

Expression, Purification, and Characterization of a Well-Adapted Tyrosinase from Peatlands Identified by Partial Community Analysis

“…The microbial community in peatland soils is dominated by bacteria, both in numbers and as far as the influence on carbon cycling is concerned (while archaea and fungi are less prevalent), − and, consequently, tyrosinase activity in peatlands is likely to be equally dominated by bacterial TYR enzymes as well. The species-rich bacterial genus of Streptomyces has been particularly associated with plant necromass degradation .…”

Biological Nitrogen Fixation and Nitrogen Accumulation in Peatlands

“…For the C/N ratio of tropical peat, we compiled a dataset of 160 records (for details of all records, see Supplementary Table S1), which consists of two types of peatlands (defined by their degradation status): natural (labeled as "undisturbed"; n = 71 records), and disturbed (drained or logged, n = 75) peatlands. For undisturbed tropical peat, the oxic, above water-table active layer of peat is approximately 10-30 cm deep (Melling et al, 2005;Girkin et al, 2020). To avoid the overrepresentation of sampling from surface soil, we divided the C/N ratios into two depth groups: surface or near surface peat ("surface peat", n = 78) and deeper peat ("lower peat", n = 51).…”