Scorched Earth: Suillus colonization of Pinus albicaulis seedlings planted in wildfire-impacted soil affects seedling biomass, foliar nutrient content, and isotope signatures
2018
Jenkins, Martha L. | Cripps, Cathy L. | Gains-Germain, Leslie
AIMS: In western North America ectomycorrhizal fungi are critical to establishment of conifers in low nitrogen soils. Fire can affect both ectomycorrhizal fungi and soil properties, and inoculation with ectomycorrhizal fungi is recommended when planting on burns for restoration. The aim of this study was to examine how Suillus species used in inoculation affect whitebark pine (Pinus albicaulis L.) seedlings planted in fire-impacted soil. METHODS: In a greenhouse experiment, Suillus-colonized and uncolonized whitebark pine seedlings were planted in unsterilized and sterilized (control) soil from a recent burn. After 6 months, foliar nitrogen and carbon content, concentration, and stable isotope values were assessed, along with growth parameters. RESULTS: When seedlings were colonized, biomass was 61% greater, foliar nitrogen content 25% higher, foliar nitrogen concentration 30–63% lower; needles had lower δ¹⁵N and higher δ¹³C. Differences were more pronounced in sterilized soil where colonization was higher. Foliar N content was negatively correlated with δ¹⁵N values. CONCLUSIONS: Colonization by host-specific fungi produced larger seedlings with higher foliar nitrogen content in both burn soils. The hypothesis that ectomycorrhizal fungi on roots fractionate nitrogen isotopes leading to lower δ¹⁵N in needles is supported. This helps explain restoration outcomes, and bridges the gap between field and in vitro investigations.
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