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Heterobasidion root disease (HRD) infection is becoming increasingly common in red pine plantations of the Lake States. Although stump treatment can reduce rates of overland transmission, infested stands continue to experience expansion of mortality pockets. Natural regeneration into HRD mortality pockets can assist with revegetation. The objective of this study was to determine what tree species naturally regenerate in red pine plantations impacted by HRD in Wisconsin and Michigan. We visited 49 pockets (in 31 stands) in Wisconsin and Michigan that had existing confirmed HRD infections during the fall of 2017. We surveyed the regeneration in the pocket and measured the species and basal area of overstory trees 10 m from the expanding edge of the pocket. Overall, pockets were regenerating with desirable species, some of which are susceptible to HRD. Additionally, woody invasive species were present in 39 percent of the pockets. We expect these pockets to generally fill with desirable species of regeneration, although long-term successful regeneration by susceptible species such as pines may be limited. [ABSTRACT FROM AUTHOR]

1 Natural forest systems constitute a major portion of the world's land area, and are subject to the potentially negative effects of both global climate change and invasion by exotic insects. A suite of invasive weevils has become established in the northern hardwood forests of North America. How these insects will respond to increasing CO2 or O3 is unknown. 2 The present study examined the effects of elevated atmospheric CO2 and O3 on the invasive weevil Polydrusus sericeus Schaller at the Aspen Free Air CO2 Enrichment (FACE) site near Rhinelander, Wisconsin. A performance assay was conducted in the laboratory during the summer of 2007 using mated pairs of P. sericeus fed a combination of aspen, birch and maple foliage. We recorded leaf area consumption, oviposition and adult longevity. We also conducted visual abundance surveys in the field from 2004 to 2007 on aspen and birch at Aspen FACE. 3 Elevated CO2, but not O3, significantly affected P. sericeus performance. Female, but not male, longevity was reduced under elevated CO2. Polydrusus sericeus also produced fewer eggs under elevated CO2 conditions compared with ambient conditions. Adult P. sericeus strongly preferred birch over both aspen and maple, regardless of fumigation treatment. 4 The effects of elevated CO2 on P. sericeus populations at Aspen FACE were minimal, and varied among years and host tree species. Polydrusus sericeus abundance was significantly greater on birch than aspen. Over the long term, elevated CO2 may reduce adult female longevity and fecundity of P. sericeus. Further studies are needed to evaluate how this information may scale to ecosystem impacts. [ABSTRACT FROM AUTHOR]