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ABSTRACT The plant–mycorrhizal fungi relationship can range from mutualistic to parasitic as a function of the fungal taxa involved, plant ontogeny, as well as the availability of resources. Despite the implications this relationship may have on forest carbon cycling and storage, we know little about how mature trees may be impacted by mycorrhizae and how this impact may vary across the landscape. We collected growth data of two arbuscular mycorrhizal fungi (AMF)‐associated tree species,Acer rubrumandA. saccharum, and one ectomycorrhizal fungi (EMF)‐associated tree species,Quercus rubra, to assess how the mycorrhizal fungi–plant association may vary along a gradient of nitrogen (N) availability. Individual assessments of fungal taxa relative abundances showed non‐linear associations with tree growth; positive associations for the two AMF‐associated trees were mostly under low N, whereas positive to neutral associations for the EMF‐associated tree mainly took place at high N. OnlyA. rubrumexhibited greater tree growth with its tree soil‐specific mycorrhizal community when compared with predictions under a random mycorrhizal soil community. Because mycorrhizal fungi are likely to mediate how plants respond to warming, increasing levels of N deposition and of atmospheric CO2, understanding these relationships is critical to accurately forecasting tree growth.
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The potential for mycobiont sharing between shrubs and seedlings to facilitate tree establishment after wildfire at Alaska arctic treeline
Abstract Root‐associated fungi, particularly ectomycorrhizal fungi (EMF), are critical symbionts of all boreal tree species. Although climatically driven increases in wildfire frequency and extent have been hypothesized to increase vegetation transitions from tundra to boreal forest, fire reduces mycorrhizal inoculum. Therefore, changes in mycobiont inoculum may potentially limit tree‐seedling establishment beyond current treeline. We investigated whether ectomycorrhizal shrubs that resprout after fire support similar fungal taxa to those that associate with tree seedlings that establish naturally after fire. We then assessed whether mycobiont identity correlates with the biomass or nutrient status of these tree seedlings. The majority of fungal taxa observed on shrub and seedling root systems wereEMF, with some dark septate endophytes and ericoid mycorrhizal taxa. Seedlings and adjacent shrubs associated with similar arrays of fungal taxa, and there were strong correlations between the structure of seedling and shrub fungal communities. These results show that resprouting postfire shrubs support fungal taxa compatible with tree seedlings that establish after wildfire. Shrub taxon, distance to the nearest shrub and fire severity influenced the similarity between seedling and shrub fungal communities. Fungal composition was correlated with both foliar C:N ratio and seedling biomass and was one of the strongest explanatory variables predicting seedling biomass. While correlative, these results suggest that mycobionts are important to nutrient acquisition and biomass accrual of naturally establishing tree seedlings at treeline and that mycobiont taxa shared by resprouting postfire vegetation may be a significant source of inoculum for tree‐seedling establishment beyond current treeline.
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- Award ID(s):
- 1636476
- PAR ID:
- 10035564
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 26
- Issue:
- 14
- ISSN:
- 0962-1083
- Page Range / eLocation ID:
- p. 3826-3838
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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