Fungal communities in soils under global change

Abstract

Soil fungi play indispensable roles in all ecosystems including the recycling of organic matter and interactions with plants, both as symbionts and pathogens. Past observations and experimental manipulations indicate that projected global change effects, including the increase of CO₂ concentration, temperature, change of precipitation and nitrogen (N) deposition, affect fungal species and communities in soils. Although the observed effects depend on the size and duration of change and reflect local conditions, increased N deposition seems to have the most profound effect on fungal communities. The plant-mutualistic fungal guilds - ectomycorrhizal fungi and arbuscular mycorrhizal fungi - appear to be especially responsive to global change factors with N deposition and warming seemingly having the strongest adverse effects. While global change effects on fungal biodiversity seem to be limited, multiple studies demonstrate increases in abundance and dispersal of plant pathogenic fungi. Additionally, ecosystems weakened by global change-induced phenomena, such as drought, are more vulnerable to pathogen outbreaks. The shift from mutualistic fungi to plant pathogens is likely the largest potential threat for the future functioning of natural and managed ecosystems. However, our ability to predict global change effects on fungi is still insufficient and requires further experimental work and long-term observations. Citation: Baldrian P, Bell-Dereske L, Lepinay C, Větrovský T, Kohout P (2022). Fungal communities in soils under global change. Studies in Mycology 103: 1-24. doi: 10.3114/sim.2022.103.01.

Keywords: deposition; drought; elevated CO2; global change; mycorrhiza; nitrogen; warming.

Fig. 1.

Major current and predicted responses to global change factors. Responses to each factor is represented by the location within each section with responses spanning multiple sections indicating the importance of multiple climate change factors.

Fig. 2.

Realised niches of the 200 most frequently observed fungal species in global soils. In panels A–D, each species is represented by a rectangle representing the lower and upper decile of the mean annual precipitation (MAP) and mean annual temperature (MAT) of locations from where it was reported. Colours indicate ecological guild membership: A) green – ectomycorrhizal fungi (n = 24), B) blue – ericoid mycorrhizal fungi (n = 9), C) purple – plant pathogens (n = 22), and D) yellow – saprotrophs (n = 125). The distribution of fungal species niche breadth in E) MAT and F) MAP with color representing guilds and pairwise significant difference between means represented by letters. Individual species are represented with columns. Data from (Větrovský et al. 2019).

Fig. 3.

Observations of the effects of selected global change factors on the A) biomass, B) diversity, C) guild composition and D) community composition of total fungi in the context of experimental length and magnitude of treatment. The pie graphs indicate the total share of experiments reporting statistically significant effects (increase, decrease, no change). Treatment intensities are in ppm applied for CO₂, increase in °C in temperature manipulation, percent reduction in precipitation and kg/ha/y in N addition. For the lists of experiments, see Tables 1–4.

Fig. 4.

Observations of the effects of selected global change factors on the A) biomass, B) diversity and C) community composition of AM fungi in the context of experimental length and magnitude of treatment. The pie graphs indicate the total share of experiments reporting statistically significant effects (increase, decrease, no change). Treatment intensities are in ppm applied for CO₂, increase in °C in temperature manipulation, percent reduction in precipitation and kg/ha/y in N addition. For the lists of experiments, see Tables 1–4.