Fungal Communities Respond to Long-Term CO ₂ Elevation by Community Reassembly

Abstract

Fungal communities play a major role as decomposers in the Earth's ecosystems. Their community-level responses to elevated CO 2 (eCO 2 ), one of the major global change factors impacting ecosystems, are not well understood. Using 28S rRNA gene amplicon sequencing and co-occurrence ecological network approaches, we analyzed the response of soil fungal communities in the BioCON (biodiversity, CO 2 , and N deposition) experimental site in Minnesota, USA, in which a grassland ecosystem has been exposed to eCO 2 for 12 years. Long-term eCO 2 did not significantly change the overall fungal community structure and species richness, but significantly increased community evenness and diversity. The relative abundances of 119 operational taxonomic units (OTU; ϳ27% of the total captured sequences) were changed significantly. Significantly changed OTU under eCO 2 were associated with decreased overall relative abundance of Ascomycota, but increased relative abundance of Basidiomycota. Cooccurrence ecological network analysis indicated that eCO 2 increased fungal community network complexity, as evidenced by higher intermodular and intramodular connectivity and shorter geodesic distance. In contrast, decreased connections for dominant fungal species were observed in the eCO 2 network. Community reassembly of unrelated fungal species into highly connected dense modules was observed. Such changes in the co-occurrence network topology were significantly associated with altered soil and plant properties under eCO 2 , especially with increased plant biomass and NH 4 ؉ availability. This study provided novel insights into how eCO 2 shapes soil fungal communities in grassland ecosystems.

Interactive network configuration maintains bacterioplankton community structure under elevated CO<sub>2</sub> in a eutrophic coastal mesocosm experiment

“…4). It has also been reported that sparsely distributed fungal species were reassembled into highly connected dense modules under long-term elevated CO 2 conditions (Tu et al, 2015).…”

“…Elucidating the complex interactions between bacterioplankton and other marine organisms under anthropogenic perturbations will increase our understanding of their impact in a holistic way. Previous studies using ecological network analysis showed that elevated CO 2 significantly impacted soil bacterial/archaeal community networks by decreasing the connections for dominant fungal species and reassembling unrelated fungal species in a grassland ecosystem (Tu et al, 2015). It was also reported using ecological network analysis that elevated pCO 2 did not significantly affect microbial community structure and succession in the Arctic Ocean, suggesting bacterioplankton community resilience to elevated pCO 2 (Wang et al, 2016).…”

Ectomycorrhizal fungal diversity predicted to substantially decline due to climate changes in North American Pinaceae forests

“…Climate change can alter the community composition of ECMF by pushing fungi (Kipfer, Egli, Ghazoul, Moser, & Wohlgemuth, ) or their host plants (Fernandez et al, ) outside their ranges of physiological tolerance (Pickles, Egger, Massicotte, & Green, ). However, most studies to date that have examined ECMF or whole fungal community responses to simulated climate change have found fairly small effects (Fernandez et al, ; Mucha et al, ; Parrent, Morris, & Vilgalys, ; Tu et al, ) relative to natural changes in fungal communities observed along large natural gradients of temperature and precipitation (Jarvis, Woodward, Alexander, & Taylor, ; Nottingham et al, ; Peay et al, ; Talbot et al, ; Tedersoo et al, ). Yet, few datasets currently exist with spatial resolution necessary to make accurate predictions of ECMF response to climate change across relevant geographic regions (Mohan et al, ).…”

Eukaryotic Biodiversity in Mixed Peat Ecosystems in Sarawak, Malaysia

“…Estimates of global fungal species richness are in the millions (Taylor et al, 2014), while less than 2% have been formally described (Taylor et al, 2016). Long-term elevated CO 2 significantly decreased overall relative abundance of Ascomycota, but increased relative abundance of Basidiomycota (Tu et al, 2015). However, the Basidiomycetous fungi activities are reduced due to the anoxic upper layers in different types of peatland (Winsborough and Basiliko, 2010).…”

“…Glomeromycota and Neocallimastigomycota were present in logged-over peat at Cermat Ceria ( Figure 5b) and absent in the other peat ecosystems (Figures 5a,5c and 5d). Glomeromycota is the phylum for most arbuscular mycorrhizal fungi, which form symbioses with many herbaceous plants (Tu et al, 2015) found in logged-over forest at Cermat Ceria, the low relative abundance of Glomeromycota resulted from perennial plant species composition (Tu et al, 2015) such as in Maludam and matured oil palm at Durafaram and Naman. Glomeromycota is an important soil microbial group that affects multiple ecosystem functions and processes, including nutrient cycling, plant productivity and competition, and plant diversity (Alguacil et al, 2016).…”