Climate suitability is projected to decline for many subalpine species, raising questions about managing species under a deteriorating climate. Whitebark pine (WBP) (Pinus albicaulis) in the Greater Yellowstone Ecosystem (GYE) crystalizes the challenges that natural resource managers of many high mountain ecosystems will likely face in the coming decades. We review the system of interactions among climate, competitors, fire, bark beetles, white pine blister rust (Cronartium ribicola), and seed dispersers that make WBP especially vulnerable to climate change. A well-formulated interagency management strategy has been developed for WBP, but it has only been implemented across <1% of the species GYE range. The challenges of complex climate effects and land allocation constraints on WBP management raises questions regarding the efficacy of restoration efforts for WBP in GYE. We evaluate six ecological mechanisms by which WBP may remain viable under climate change: climate microrefugia, climate tolerances, release from competition, favorable fire regimes, seed production prior to beetle-induced mortality, and blister-rust resistant trees. These mechanisms suggest that WBP viability may be higher than previously expected under climate change. Additional research is warranted on these mechanisms, which may provide a basis for increased management effectiveness. This review is used as a basis for deriving recommendations for other subalpine species threatened by climate change.

Lactarius (Russulales) is an important component of ectomycorrhizal fungal communities in cold-dominated contiguous arctic and disjunct alpine habitats where it associates primarily with Betula, Dryas and Salix However, little is known of this genus in the central and southern Rocky Mountain alpine zone (3000-3900 m) of North America. Molecular phylogenetic analyses of nuc rDNA ITS1-5.8S-ITS2 (ITS barcode) and the second largest subunit of the RNA polymerase II gene (RPB2) partial sequences in conjunction with detailed morphological examination confirm at least six species occurring above treeline. Most have intercontinental distributions in North America and Eurasia according to molecular comparison with type material and collections from Europe, Fennoscandia, Svalbard and Alaska. Rocky Mountain collections of L. lanceolatus (subgenus Russularia), along with the type from Alaska are paraphyletic with respect to L. aurantiacus and North American taxa L. luculentus and L. luculentus v. laetus Rocky Mountain collections of L. nanus, L. glyciosmus, L. repraesentaneus and L. salicis-reticulatae (subgenus Piperites) all form clades with European material from type localities and other arctic-alpine habitats. The arctic-alpine L. pseudouvidus/L. brunneoviolaceus group appears to be a complex containing additional taxa. North American material originally described as part of this group is well-separated phylogenetically and is described here as L. pallidomarginatus sp. nov. Lactarius lanceolatus, L. nanus and L. salicis-reticulatae appear largely restricted to arctic-alpine habitats with Salix Lactarius glyciosmus and L. repraesentaneus occur in arctic-alpine, subalpine and boreal habitats with Betula and also Picea and possibly Salix for the latter. Species distributions are hypothesized to be shaped by host ranges, glaciation and long distance dispersal.

Aim: Foliar fungi -pathogens, endophytes, epiphytes -form taxonomically diverse communities that affect plant health and productivity. The composition of foliar fungal communities is variable at spatial scales both small (e.g. individual plants) and large (e.g. continents), yet few studies have attempted to tease apart spatial from climatic factors influencing these communities. Moreover, few studies have sampled in more than 1 year to gauge interannual variation in community structure. Location:The Pacific Northwest of western North America.Taxon: Foliar fungi associated with the deciduous tree Populus trichocarpa. Methods:In two consecutive years, we used DNA metabarcoding to characterize foliar fungal communities of Populus trichocarpa across its geographic range, which encompasses a sharp climatic transition as it crosses the Cascade Mountain Range.We used multivariate analyses to (a) test for and differentiate spatial and environmental factors affecting community composition and (b) test for temporal variation in community composition across spatial and environmental gradients. Results:In both study years, we found that foliar fungal community composition varied among sites and between regions (east vs. west of the Cascades). We found that climate explained more variation in community composition than geographic distance, although the majority of variation explained by each was shared. We also found that interannual variation in community composition depended on environmental context: communities located in the dry, eastern portion of the tree's geographic range varied more between study years than those located in the wet, western portion of the tree's range. Main conclusions:Our results suggest that the environment plays a greater role in structuring foliar fungal communities than dispersal limitation. K E Y W O R D S Cascade Mountain Range, fungal leaf endophyte, microbial community structure, plant pathogen 1 | INTRODUC TI ON Foliar fungi exist in and on living plant leaves. The most well-known members of these communities are pathogenic fungi, which cause plant disease and thereby affect the structure and composition of plant communities (Gilbert, 2002). Less well understood are the non-pathogenic epiphytic and endophytic fungi. These fungi are functionally diverse and can be mutualists (Arnold, 2007; Arnold et B I OS K E TCH Edward Barge is a PhD student in the Botany and Plant Pathology Department at Oregon State University. He is working with mentor Posy Busby to characterize the taxonomic structure and ecological function of microbial communities that live in and on plant tissues (https ://bpp.orego nstate.edu/users/ posy-busby ).

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The Greater Yellowstone Ecosystem (GYE), located in the Central Rocky Mountains of western North America, is one of the largest nearly intact temperate-zone ecosystems on Earth. Here, Lactarius is an important component of ectomycorrhizal communities in many habitat types, from low elevation riparian areas to high elevation conifer forests and alpine tundra. Molecular phylogenetic analyses of ITS and RPB2 gene sequences along with detailed morphological examination confirm at least 20 Lactarius species, as well as three varieties, and one unresolved species group in the GYE. Eight taxa are reported from the GYE for the first time, and nearly every major ectomycorrhizal host plant in the GYE appears to have at least one Lactarius species associated with it. Broad intercontinental distributions are suggested for alpine Salix and Betula associates, and for certain subalpine Picea and aspen (Populus spp.) associates. Some species appear to be restricted to western North America with Pinus, Pseudotsuga or Abies. The distribution and/or host affinities of others is not clear due in part to ambiguous host assignment, taxonomic problems or the relative rarity with which they have been reported. Key words