Effects of simulated warming on bacterial diversity and abundance in tropical soils from East Malaysia using open top chambers

Abstract

The effects of global warming are increasingly evident, where global surface temperatures and atmospheric concentration of carbon dioxide have increased in past decades. Given the role of terrestrial bacteria in various ecological functions, it is important to understand how terrestrial bacteria would respond towards higher environmental temperatures. This study aims to determine soil bacterial diversity in the tropics and their response towards in situ warming using an open-top chamber (OTC). OTCs were set up in areas exposed to sunlight throughout the year in the tropical region in Malaysia. Soil samples were collected every 3 months to monitor changes in bacterial diversity using V3–V4 16S rDNA amplicon sequencing inside the OTCs (treatment plots) and outside the OTCs (control plots). After 12 months of simulated warming, an average increase of 0.81 to 1.15 °C was recorded in treatment plots. Significant changes in the relative abundance of bacterial phyla such as Bacteroidetes and Chloroflexi were reported. Increases in the relative abundance of Actinobacteria were also observed in treatment plots after 12 months. Substantial changes were observed at the genus level, where most bacterial genera decreased in relative abundance after 12 months. This study demonstrated that warming can alter soil bacteria in tropical soils from Kota Kinabalu.

Forecasting the impact of global warming on soil bacterial communities using simulated systems

“…The warming impact and heat entrapment of soils inside the OTCs are validated in various studies. The difference in soil temperature between the treatment plots and control plots was between 0.81 °C to 1.15 °C (Chua and Wong, 2021), similar result is reported by Bokhorst et al (2011) (0.5 °C to 1.4 °C). A study by Yergeau et al (2011) recorded an average soil surface temperature of 0.7 °C inside OTC, while Camac et al (2015) observed a 1.2 °C increase in average soil surface temperature.…”

“…Planctomycetes and Actinobacteria are better acclimated to higher temperatures, while other bacterial groups, like Acidobacteria, Betaproteobacteria and Deltaproteobacteria experience a decrease in relative abundance as the temperature rises (Rui et al, 2015). Research done by Chua and Wong (2021) showed that increases in the relative abundance of Actinobacteria and Chloroflexi were observed after twelve months of in situ OTC-simulated warming, while a significant decrease in the relative abundance of Bacteroidetes was recorded.…”

“…The plots should be clear to retain the OTCs in position during high winds or in situations when removal of the OTCs is necessary for specific measurements such as measurement of vegetation potential or vegetation solar spectral reflectance within the OTCs (Hollister et al, 2023). Overall, minimal environmental disruption, easy deployment and low maintenance costs make OTCs a good choice for simulated warming studies (Chua and Wong, 2021;Hollister et al, 2023).…”

“…In addition, Chua and Wong (2021) conducted a similar study in tropical soils in Malaysia aimed at improving our understanding of the effects of rising temperatures on the composition of terrestrial bacteria in tropical soils. Although the study only lasted a year, they discovered a significant decrease in the relative abundance of Bacteroidetes and an increase in the relative abundance of Chloroflexi at the phylum level.…”

“…These simulated models allow researchers to manipulate key environmental variables, including temperature and observe the corresponding changes in soil bacterial diversity and composition. Various researchers have used various simulation strategies in the past (Price and Waser, 2000;Emmett et al, 2004;Chua and Wong, 2021), each with their own set of advantages and disadvantages, as discussed in the following sections. The results generated using these systems and some mitigation strategies for retaining beneficial soil bacteria are discussed.…”