Ectomycorrhizal fungal response to warming is linked to poor host performance at the boreal‐temperate ecotone

Abstract

Rising temperatures associated with climate change have been shown to negatively affect the photosynthetic rates of boreal forest tree saplings at their southern range limits. To quantify the responses of ectomycorrhizal (EM) fungal communities associated with poorly performing hosts, we sampled the roots of Betula papyrifera and Abies balsamea saplings growing in the B4Warmed (Boreal Forest Warming at an Ecotone in Danger) experiment. EM fungi on the root systems of both hosts were compared from ambient and +3.4 °C air and soil warmed plots at two sites in northern Minnesota. EM fungal communities were assessed with high-throughput sequencing along with measures of plant photosynthesis, soil temperature, moisture, and nitrogen. Warming selectively altered EM fungal community composition at both the phylum and genus levels, but had no significant effect on EM fungal operational taxonomic unit (OTU) diversity. Notably, warming strongly favored EM Ascomycetes and EM fungi with short-contact hyphal exploration types. Declining host photosynthetic rates were also significantly inversely correlated with EM Ascomycete and EM short-contact exploration type abundance, which may reflect a shift to less carbon demanding fungi due to lower photosynthetic capacity. Given the variation in EM host responses to warming, both within and between ecosystems, better understanding the link between host performance and EM fungal community structure will to clarify how climate change effects cascade belowground.

Poor plant performance under simulated climate change is linked to mycorrhizal responses in a semi‐arid shrubland

“…In contrast, the opposite response (i.e. decreased plant photosynthesis along with decreased EMF relative abundance and richness under warming) has been recently reported in a boreal/temperate ecotone ecosystem located near the lower latitudinal limit of the host plant range where productivity is limited by water availability (Fernandez et al., ). We found that warming, rainfall reduction and their combination altered ectomycorrhizal community structure and led to drastic decreases in the relative abundance of EMF sequences in the rhizosphere of H. squamatum , which is the only EMF host plant species at our study site.…”

“…saprotrophs) did not change significantly in the climate manipulation treatments. This strongly suggests that altered EMF community structure and decreased relative abundance of EMF sequences with climate manipulation was linked to plant responses and largely driven by decreased carbon supply to mycorrhizae from their stressed host plants under hotter and/or drier conditions (Castaño et al., ; Fernandez et al., ).…”

Extreme rainfall affects assembly of the root‐associated fungal community

“…Negative values were considered zeros before data were finally converted to relative abundances (as percentage of normalized read numbers) as per Fernandez et al . (). The negative binomial model performed within D e S eq 2 can simultaneously account for variation in library sizes and biological variability better than simply subsampling to a uniform sequencing depth alone.…”

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

“…The relative abundance of ECMF exploration strategies (% of ECMF OTUs) per site were assigned by matching ECMF genera against published lists (Agerer, ; Tedersoo & Smith, ), which are available online (http://www.deemy.de). Strategies were assigned to the following categories according to Fernandez et al (): contact short (CS), contact medium (CM) and medium long (ML). Because of potential differences in the relationship between DNA copy number and fungal biomass, particularly among functional groups known to differ in their morphology, we restricted our analyses to intraguild comparisons (e.g.…”

“…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, ).…”