Forest Investment Account (FIA) - Forest Science Program
FIA Project Y091062

    Underlying biological processes: the role of ectomycorrhizal fungal communities in early growth and relocation success of whitebark pine under climate change
 
Project lead: Massicotte, Hugues B. (University of Northern British Columbia)
Contributing Authors: Massicotte, Hugues B.; Green, D. Scott; Tackaberry, Linda E.
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
Description:
In a 1-year greenhouse bioassay, the proposed project will examine how soils from subalpine habitats (specifically, those containing whitebark pine (WBP)) and alpine sites (with no WBP) impact seedling growth adaptive traits and symbiotic root-fungal (ectomycorrhizas=ECM) communities. To explore limits of location and population sensitivity, soils from multiple locations and geographically distinct WBP seed populations (south and north interior BC) will be used. Within the context of climate change, we expect study findings will extend our understanding of how WBP may respond to natural or assisted relocation under genetic, soil microbial, and elevation shifts.

Whitebark pine (Pinus albicaulis Engelm.), a high elevation conifer limited to subalpine to treeline habitats in western North America, is experiencing dramatic declines in many populations across its range. In Canada, efforts are underway to list WBP as a ‘species at risk’ (J Vinnedge, BC MoE, pers comm). Historically, it has dominated upper subalpine forests (3) where it is considered a ‘keystone species’, upon which many other species depend for their survival and persistence (11). Where risk of ecological impacts is high, proactive management in high elevation forests might sustain threatened species and ecosystem function under present and predicted climate change (8).

WBP, a pioneer species, often persists in these landscapes over a long time interval. It is unlikely, therefore, to move rapidly towards adaptive change in response to environmental stress (8). If WBP cannot adapt to local change, it must expand naturally (or by intervention) into present alpine areas, or northward in latitude with climate change. In addition to changing environments, other major threats leading to significant losses in WBP populations include the white pine blister rust and the mountain pine beetle as it spreads eastward and upward, infecting lower elevation lodgepole pine before threatening mature, cone-bearing WBP trees (12,13). Climate shifts leading to seasonal warming and increased moisture, favor both white pine blister rust and mountain pine beetle. Under climate warming, WBP may also not be able to out compete more shade-tolerant high elevation species such as subalpine fir and Engelmann spruce that often share these transitional ecosystems (9); seedling recruitment may decrease due to lower seed production, germination and establishment sensitivity to environmental variations. For relocation and seedling establishment to be successful, any new area must be suitable with respect to both soil microbial processes as well as soil abiotic factors. All species in the Pinaceae (including WBP), form obligate root-fungal symbiosis (ECM) that aid seedling establishment and sustainability through improved water uptake, as well as N and P nutrient acquisition (7). In nutrient-poor alpine soils, this may be critical to species establishment.

Overall, studies on WBP microbial and (or) soil growth constraints are greatly lacking. There is almost no understanding of the underlying biology in WBP root-soil interactions that could provide important information for the conservation, protection and transfer of WBP, given the species limited range and migratory potential. In response to growing threats, efforts are underway in BC to collect WBP cones for possible restoration and WBP trials (D Kolotelo, BC MoFR, pers comm), and Parks Canada is involved in trial projects for prescribed fire in high elevation Rocky Mountain parks to improve WBP regeneration. In August 2007, the Forest Genetics Council of BC sponsored a workshop (Whitebark Pine in Western Canada) to address current research and management issues, including climate change, white pine blister rust and mountain pine beetle attack.

The proposed study will examine variables of WBP ECM fungal communities as they relate to early seedling growth in soils collected from subalpine mixed-WBP forests and alpine ecosystems (projected future sites that currently have no WBP). Several studies suggest a decrease in conifer-ECM fungal communities as distance increases from the forest edge (5,1). Recently, Mohatt (6) examined ECM fungi of naturally regenerating WBP seedlings in mature forests and adjacent avalanche slopes near Yellowstone Park. They identified 19 distinct ECM fungal taxa on WBP roots, but no difference in ECM species richness between the mature forest and avalanche slopes. Along elevation gradients, slightly lower ECM richness occurred at the bottom of avalanche paths. Avalanche seedlings naturally regenerated on paths and those selected were not further than 11-22 m from mature forest edge. The study did not measure growth nor examine areas beyond the current WBP forest. The current study will be used to clarify biological limits as well as the suitability of prospective sites, and the capacity of WBP to respond to these variables and to relocation.

The ability of WBP to persist at high elevations confers on this species a vital role in slope stabilization, plant succession, and containment of snowmelt for watershed protection. These conditions are critical to the management and silviculture practices on these slopes, and to community succession. Climate warming will potentially result in replacement of WBP forests and lead to changes in current plant and wildlife diversity, as well as snow capture and watershed hydrology (10). Although well adapted to cold, geographic variation in cold hardiness in WBP may restrict its transfer; seed transfer from warmer to colder winter environments may result in seedling cold injury (2). Latitudinal variation in conifer growth also suggests potential limitations to seed transfer across elevations (4). Transfer limitations with respect to seed populations may be further confounded if fungal communities are lacking or restricted in new locations, or if WBP populations have variable affinities to ECM fungal communities. The current study will examine growth traits of seedlings from both southern and northern WBP populations with respect to ECM fungal inoculum potential in elevation soils. Growth response data will extend present knowledge on how seed origin, outplanting choices and soil communities may impact establishment. Within the context of climate warming, understanding why a species may or may not be able to successfully re-establish or relocate could inform and direct management decisions for relocation or conservation efforts for numerous conifer species.

Although species extinction is not likely imminent for WBP, local extinctions due to one or more combined threats could impact WBP genetic diversity (i.e. possible loss or redistribution of adaptive response traits of some populations) as well as ecosystem function (8). To our knowledge, no studies have been identified that measure possible WBP ECM or soil limitations that relate to growth adaptations in the northern range of this species.

Refs 1-Bidartondo MI et al 2001 Can J Bot 79: 293-299; 2-Bower AD, SN Aitken 2006 Can J For Res 36: 1842-1850; 3-Campbell EM, JA Antos 2000 Can J For Res 30: 1051-1059; 4-Green DS 2005 Can J For Res 35: 910-917; 5-Kranabetter JM, J Friesen 2002 Can J Bot 80: 861-868; 6-Mohatt KR 2006 MS thesis, Montana State U; 7-Molina R et al 1992 In Mycorrhizal functioning Ed MF Allen, Routledge, Chapman and Hall, NY pp. 357-423; 8-Schoettle AW, RA Sniezko 2007 J For Res 12: 327-336; 9-Tomback DF et al 2001 In Tomback DF, SF Arno, RE Keane eds. Whitebark pine communities, Washington DC: Island press: 3-25; 10-Tomback DF, KC Kendall 2001 In Tomback DF, SF Arno, RE Keane eds. Whitebark pine communities Washington DC: Island press: 243-262; 11-Tomback DF 2007 In Conf. Proc. Whitebark pine Ed EM Goheen, RA Sniezko, USDA FS R6-NR-FHP-2007-1, pp 6-19; 12-Zeglen S 2002 Can J For Res 32: 1265-1274; 13-Zeglen S 2007 In Conf. Proc. Whitebark pine, Ed by EM Goheen, RA Sniezko, USDA FS R6-NR-FHP-2007-1, pp 36-38

Contact: Massicotte, Hugues B., (250) 960-5813, hugues@unbc.ca

    Deliverables:

Executive summary (91Kb)

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Updated August 16, 2010 

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