Resilience of Arctic Mycorrhizal Fungal Communities after Wildfire Facilitated by Resprouting Shrubs Author(s): Rebecca E. Hewitt , Elizabeth Bent , Teresa N. Hollingsworth , F. Stuart Chapin III & D. Lee Taylor Source: Ecoscience, 20(3):296-310. 2013. Published By: Centre d'études nordiques, Université Laval DOI: http://dx.doi.org/10.2980/20-3-3620 URL: http://www.bioone.org/doi/full/10.2980/20-3-3620 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. 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BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. ௅ Resilience of Arctic mycorrhizal fungal communities after wildfire facilitated by resprouting shrubs1 5HEHFFD(+(:,772 (OL]DEHWK%(173,'HSDUWPHQWRI%LRORJ\DQG:LOGOLIH,QVWLWXWHRI$UFWLF%LRORJ\ 8QLYHUVLW\RI$ODVND)DLUEDQNV)DLUEDQNV$ODVND86$HPDLOUHKHZLWW#DODVNDHGX 7HUHVD1+2//,1*6:257+ US Forest Service, Pacific Northwest Research Station, Boreal Ecology &RRSHUDWLYH5HVHDUFK8QLW)DLUEDQNV$ODVND86$ )6WXDUW&+$3,1,,, '/HH7$</254,'HSDUWPHQWRI%LRORJ\DQG:LOGOLIH,QVWLWXWHRI $UFWLF%LRORJ\8QLYHUVLW\RI$ODVND)DLUEDQNV)DLUEDQNV$ODVND86$ Abstract: Climate-induced changes in the tundra fire regime are expected to alter shrub abundance and distribution across the Arctic. However, little is known about how fire may indirectly impact shrub performance by altering mycorrhizal symbionts. :HXVHGPROHFXODUWRROVLQFOXGLQJ$5,6$DQGIXQJDO,76VHTXHQFLQJWRFKDUDFWHUL]HWKHP\FRUUKL]DOFRPPXQLWLHVRQ resprouting Betula nana shrubs across a fire-severity gradient after the largest tundra fire recorded in the Alaskan Arctic -XO\±2FWREHU )LUHHIIHFWVRQWKHFRPSRQHQWVRIIXQJDOFRPSRVLWLRQZHUHGHSHQGDQWRQWKHVFDOHRIWD[RQRPLF resolution. Variation in fungal community composition was correlated with fire severity. Fungal richness and relative DEXQGDQFHRIGRPLQDQWWD[DGHFOLQHGZLWKLQFUHDVHGILUHVHYHULW\<HWLQFRQWUDVWWRWHPSHUDWHDQGERUHDOUHJLRQVZLWK frequent wildfires, mycorrhizal fungi on resprouting shrubs in tundra were not strongly differentiated into fire-specialists DQGILUHVHQVLWLYHIXQJL,QVWHDGGRPLQDQWIXQJLLQFOXGLQJWD[DFKDUDFWHULVWLFRIODWHVXFFHVVLRQDOVWDJHVZHUHSUHVHQW UHJDUGOHVVRIILUHVHYHULW\,WLVOLNHO\WKDWWKHUHVSURXWLQJOLIHKLVWRU\VWUDWHJ\RIWXQGUDVKUXEVFRQIHUVUHVLOLHQFHRIGRPLQDQW mycorrhizal fungi to fire disturbance by maintaining an inoculum source on the landscape after fire. Based on these results, we suggest that resprouting shrubs may facilitate post-fire vegetation regeneration and potentially the expansion of trees and shrubs under predicted scenarios of increased warming and fire disturbance in Arctic tundra. Keywords: Arctic tundra, Betula nanaILUHIXQJDOLQWHUQDOWUDQVFULEHGVSDFHU ,76 UHJLRQP\FRUUKL]DOFRPPXQLW\VWUXFWXUH nurse plant. Résumé2QV DWWHQGjFHTXHGHVFKDQJHPHQWVGDQVOHUpJLPHGHVIHX[GDQVODWRXQGUDFDXVpVSDUOHFOLPDWPRGLILHQW O DERQGDQFHHWODGLVWULEXWLRQGHVDUEXVWHVjWUDYHUVO $UFWLTXH&HSHQGDQWODPDQLqUHGRQWOHIHXSRXUUDLWDYRLUXQHIIHW LQGLUHFWVXUODSHUIRUPDQFHGHVDUEXVWHVHQSHUWXUEDQWOHVV\PELRWHVP\FRUKL]LHQVHVWSHXFRQQXH1RXVDYRQVXWLOLVpGHV RXWLOVPROpFXODLUHVGRQW$5,6$HWOHVpTXHQoDJHGHV,76IRQJLTXHVSRXUFDUDFWpULVHUOHVFRPPXQDXWpVGHP\FRUKL]HVGDQV des rejets d’arbustes de Betula nanajWUDYHUVXQJUDGLHQWGHVpYpULWpGHIHXjODVXLWHGXSOXVJUDQGLQFHQGLHD\DQWMDPDLV HXOLHXGDQVODWRXQGUDDUFWLTXHGHO¶$ODVND MXLOOHWRFWREUH /HVHIIHWVGXIHXVXUODFRPSRVLWLRQIRQJLTXHpWDLHQW GpSHQGDQWVGHO pFKHOOHGHUpVROXWLRQWD[RQRPLTXH/HVYDULDWLRQVGDQVODFRPSRVLWLRQGHODFRPPXQDXWpIRQJLTXHpWDLHQW FRUUpOpHVDYHFODVpYpULWpGXIHX/DULFKHVVHIRQJLTXHHWO¶DERQGDQFHUHODWLYHGHVWD[RQVGRPLQDQWVGLPLQXDLHQWDYHFXQH DXJPHQWDWLRQGHODVpYpULWpGXIHX7RXWHIRLVFRQWUDLUHPHQWDX[UpJLRQVWHPSpUpHVHWERUpDOHVROHVIHX[G RULJLQHQDWXUHOOH VRQWIUpTXHQWVOHVFKDPSLJQRQVP\FRUKL]LHQVREVHUYpVVXUGHVUHMHWVG DUEXVWHVGDQVODWRXQGUDQ¶pWDLHQWSDVFODLUHPHQW GLIIpUHQFLpVHQWUHHVSqFHVVSpFLDOLVWHVGXIHXHWHVSqFHVVHQVLEOHVDXIHX(QHIIHWOHVFKDPSLJQRQVGRPLQDQWVLQFOXDQW GHVWD[RQVFDUDFWpULVWLTXHVGHVGHUQLHUVVWDGHVVXFFHVVLRQQHOVpWDLHQWSUpVHQWVLQGpSHQGDPPHQWGHODVpYpULWpGXIHX,O HVWSUREDEOHTXHODVWUDWpJLHG¶KLVWRLUHGHYLHGHVDUEXVWHVGHODWRXQGUDTXLFRPSUHQGODSURGXFWLRQGHUHMHWVFRQIqUHXQH UpVLOLHQFHDX[FKDPSLJQRQVP\FRUKL]LHQVGRPLQDQWVIDFHDX[SHUWXUEDWLRQVSDUOHIHXHQPDLQWHQDQWGDQVOHSD\VDJHDSUqV IHXXQHVRXUFHG LQRFXOXP(QQRXVEDVDQWVXUFHVUpVXOWDWVQRXVVXJJpURQVTXHODSURGXFWLRQGHUHMHWVSDUOHVDUEXVWHV SRXUUDLWIDFLOLWHUODUpJpQpUDWLRQGHODYpJpWDWLRQDSUqVIHXHWSRWHQWLHOOHPHQWO H[SDQVLRQG DUEUHVHWG¶DUEXVWHVGDQVGHV VFpQDULRVGHUpFKDXIIHPHQWFOLPDWLTXHHWG¶DXJPHQWDWLRQGHVIHX[GDQVODWRXQGUDDUFWLTXH Mots-clés : Betula nanaHVSDFHXUWUDQVFULWLQWHUQH UpJLRQ,76 IRQJLTXHIHXSODQWHFRPSDJQHVWUXFWXUHGHODFRPPXQDXWp de mycorhizes, toundra arctique. Nomenclature$QQRWDWHG&KHFNOLVWRIWKH3DQDUFWLF)ORUDRQOLQH,QGH[)XQJRUXP3DUWQHUVKLSRQOLQH Introduction Fire frequency and severity play a strong role in regu- (Racine et al./DQW]*HUJHO +HQU\ \HW lating shrub regeneration and distribution in the Arctic little is known about the response to fire of soil fungal com- munities critical to shrub growth. Shifts in the tundra fire 5HFDFF regime could influence vegetation change directly by open- $VVRFLDWH(GLWRU7LP0RRUH ing new microsites for colonization and succession (White, 2 Author for correspondence. RULQGLUHFWO\E\DOWHULQJWKHDYDLODELOLW\RIFULWLFDO 3 Present address: School of Environmental Sciences, University of Guelph, Guelph, fungal symbionts, ectomycorrhizal fungi (EMF), that influ- 2QWDULR1*:&DQDGD 4 Present address: Department of Biology, University of New Mexico, Albuquerque, ence host plant performance (Hoeksema et al. ,Q 1HZ0H[LFR86$ general, fire effects on mycobionts are governed by burn '2, severity, which impacts the availability of host plants, and ÉCOSCIENCE, VOL. 20 (3), 2013 the depth of burning in the soil profile (Neary et al. VSRUHVDQG³ODWHVWDJH´IXQJLZKLFKFRORQL]HURRWVRI &HUWLQL ,WLVWKHUHIRUHOLNHO\WKDW(0)UHVSRQVH more mature trees and spread by mycelial growth but not to fire disturbance may be an important determinant of E\VSRUHV 'HDFRQ'RQDOGVRQ /DVW)R[ post-fire vegetation regeneration and expansion in the 1HZWRQ :KLOHWKLVFODVVLILFDWLRQV\VWHPLVOLNHO\ Alaskan Arctic. over-simplistic, the wide dispersal and rapid colonization High-latitude climate warming has altered landscape- of the early colonizers is suggestive of an r-strategy, while scale disturbance regimes in the Arctic (Hu et al. the later colonizers display some attributes consistent with a 7XQGUDILUHVRQWKH1RUWK6ORSHRI$ODVNDZHUHUDUHRFFXU- .VWUDWHJ\,QDGGLWLRQWR(0)KRVWSODQWVWKDWDUHSULPDU- UHQFHVRYHUWKHODVW\ +X et al. GXHWRFRRO ily ectomycorrhizal sometimes associate with dark septate moist conditions and low biomass of dry fuels (Wein, endophytes (DSE) and ericoid mycorrhizal fungi (ERM) ,QFUHDVHGIUHTXHQF\RIZDUPZHDWKHUWRJHWKHUZLWK 7HGHUVRR et al., 2009). Mycorrhizal composition has dif- ORZVXPPHUSUHFLSLWDWLRQ 6KXOVNL :HQGOHU ferential effects on host plant performance through nutri- however, has caused a non-linear increase in tundra area ent translocation, water uptake, carbon cost, and pathogen burned annually (Hu et al. ,QWKH$QDNWXYXN resistence, among other factors (Smith & Read, 2008). River Fire (ARF), the largest tundra fire recorded in the 7KXVLWLVOLNHO\WKDWVKLIWVLQP\FRUUKL]DOFRPSRVLWLRQ FLUFXPSRODU$UFWLFEXUQHG NP2 on the North Slope due to fire have an impact on mycorrhiza-mediated host RI$ODVND7KH$5)ZDVXQSUHFHGHQWHGLQERWKVL]HDQG plant performance and may influence shrub expansion into severity in the modern fire record and may be a harbinger of non-shrub tundra. Host plants that survive fire, such as greater landscape flammability in a future warmer climate resprouting shrubs, however, may maintain their pre-fire (Jones et al., 2009). Climate-sensitive changes in the fire mycorrhizal partners and facilitate mycorrhizal resilience regime are predicted to accelerate vegetation change attrib- to fire. uted to climate warming across the Arctic (Landhausser Here, we conducted the first investigation on the :HLQ LQFOXGLQJLQFUHDVHGVKUXEDEXQGDQFHDQG effects of fire on mycorrhizal community structure in Arctic shrub tundra expansion into graminoid tundra. tundra. We sampled roots from resprouting B. nana and Betula nana, one of the 4 dominant vascular plants used molecular tools to characterize fungal community in northern Alaskan tundra (Walker et al. H[KLELWV composition across a fire-severity gradient in the ARF. increased productivity in response to warming (Bret-Harte, 7KLVEXUQVFDULVLGHDOIRUVWXG\LQJILUHVHYHULW\HIIHFWVRQ 6KDYHU =RHUQHU DQGLVWKHRQO\GRPLQDQWVSHFLHV mycorrhizal communities because the large area burned that is obligately ectomycorrhizal (Molina et al. allowed us to examine landscape effects of fire on EMF While dwarf shrubs such as B. nana resprout from below- communities, and the wide spectrum of burn severities ground stems after fire, recovery to pre-fire productivity within the burn scar allowed us to investigate fire effects