Incidence and ecology of the chaga fungus (Inonotus obliquus) in hardwood New England – Acadian forests

Inonotus obliquus (Ach. ex Pers.) Pilát is a fungal pathogen of birch trees (Betula spp.) and other hardwoods that produces a sterile conk known colloquially as chaga. Chaga has medicinal value as an anti-mutagen and for gastro-peptic relief. Chaga harvesting has recently increased throughout its natural range in North America, including the White Mountain National Forest (WMNF). There is currently a lack of knowledge on chaga resource incidence and ecology in North America, which this project sought to rectify. Two surveys were conducted in 2017 and 2018 in the WMNF, totaling 2611 sampled trees. Positive correlations were found between chaga presence and mean stand tree age, diameter at breast height, and elevation. Overall chaga frequency was low (3.75%); however, sclerotia were widely distributed throughout the study area, with infected trees clustering. Chaga presence did not correlate with stand-level species composition or annual basal area increment, though it did appear with significantly greater frequency in yellow birch trees compared with other birch species. Additional damages related to biotic and abiotic stressors did not correlate with chaga presence, except for those resulting directly from chaga presence. These results have important silvicultural and forest management implications for chaga harvest practices across its North American range.

Reply to the comment by Bailey et al. on “Long-term decline of sugar maple following forest harvest, Hubbard Brook Experimental Forest, New Hampshire”

Sugar maple decline in eastern North America is caused by a complex combination of factors, with soil nutrition being one of several important determinants. Given the complexity of sugar maple population dynamics and the geographic extent of the species, we support Bailey et al.’s (2019, Can. J. For. Res. 49(7), doi: 10.1139/cjfr-2018-0207 ) argument to interpret results from Cleavitt et al. (2018, Can. J. For. Res. 48(1): 23–31, doi: 10.1139/cjfr-2017-0233 ) with due caution. The experiment at Hubbard Brook Experimental Forest represents an atypical application of contemporary forest practice in the White Mountain National Forest; however, some comments in Bailey et al. (2019) missed the point; others inaccurately characterized our paper. Cleavitt et al.’s (2018) 30-year record of vegetation recovery following whole-tree harvest documented a worrisome inability of a sugar maple population that successfully established after harvest to maintain its position in the understory. This lack of persistence on base-poor soils such as those in the mid and upper elevations of Hubbard Brook Experimental Forest suggests that the successful recruitment of sugar maple is not guaranteed.

Climate-Related Distribution Shifts of Migratory Songbirds and Sciurids in the White Mountain National Forest

Climate change has been linked to distribution shifts and population declines of numerous animal and plant species, particularly in montane ecosystems. The majority of studies suggest both that low-elevation avian and small mammal species are shifting up in elevation and that high-elevation avian communities are either shifting further upslope or relocating completely with an increase in average local temperatures. However, recent research suggests numerous high elevation montane species are either not shifting or are shifting down in elevation despite the local increasing temperature trends, perhaps as a result of the increased precipitation at high elevations. In this study, we examine common vertebrate species distributions across the Hubbard Brook valley in the White Mountain National Forest, including resident and migratory songbirds and small mammals, in relation to historic spring temperature and precipitation. We found no directional change in distributions through time for any of the species. However, we show that the majority of low-elevation bird species in our study area respond to warm spring temperatures by shifting upslope. All bird species that shifted were long-distance migrants. Each low-elevation migrant species responded differently to warm spring temperatures, through upslope distribution expansion, downslope distribution contraction, or total distribution shift upslope. In contrast, we found a majority of high-elevation bird species and both high- and low-elevation mammal species did not shift in response to spring temperature or precipitation and may be subject to more complex climate trends. The heterogeneous response to climate change highlights the need for more comprehensive studies on the subject and careful consideration for appropriate species and habitat management plans in northeastern montane regions.