Phellinus weirii and other native root pathogens as derterminants of forest structure and process in western North America
ABSTRACT The population structure and ecological roles of the indigenous pathogen Phellinus weirii, cause of laminated root rot in conifer forests of western North America, are examined. This pathogen kills trees in slowly expanding mortality centers, creating gaps in the forest canopy. It is widespread, locally abundant, and very long-lived. It is among the most important disturbance agents in the long intervals between stand-replacing events such as wildfire or harvest in these ecosystems and shapes the structure and composition of both wild and managed forests. Trees are infected and killed regardless of individual vigor. Management of public lands is changing dramatically, with renewed emphasis on natural forest structures and processes but pathogens, especially root rot fungi, remain a significant challenge to "ecosystem management."
Canadian Journal of Forest Research 06/2015; DOI:10.1139/cjfr-2014-0512 · 1.66 Impact Factor
- "Thinnings, for example, are well known to increase tree resistance to insect pests such as bark beetles (reviewed by Fettig et al. (2007) and Coops et al. (2009)) or spruce budworms (e.g., Bauce and Fuentealba 2013). The impacts of thinning on the resistance against fungi are less studied, and in the case of root pathogens, the results remain controversial (Waring et al. 1987; Entry et al. 1991; Hansen and Goheen 2000). To our knowledge, the question of whether harvesting of the surrounding trees can mitigate the dieback of mature ash trees has not been addressed. "
- "New methods yielding rapid woody sample identifications could facilitate determinations of biological activities, interactions, and ecological roles of microorganisms, insects, and other invertebrates that interact with wood in living and dead trees or coarse woody debris on the forest floor. Organisms associated with wood in forest ecosystems are involved in such activities as wood decomposition, nutrient cycling, and other functional niches that affect forest stand structure, dynamics, and ecosystem processes (Andrews and Harris, 2000; Hansen and Goheen, 2000; Whipps, 2001). Many microbes have effects on forest health and ecosystem functions because they include causal agents of tree mortality, forest diseases, wood decay, and lumber defects of importance in ecosystem and timber management, and in the manufacture of forest products. "
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- "On the positive side are various types of mycorrhizal associations that aid in mineral uptake, as well as several other beneficial aspects, including soil structure formation and maintenance (Miller and Jastrow, 2000). On the negative side are a variety of root-borne pathogens that may severely impact plant populations and, in some instances indirectly contribute to major shifts in ecosystem viability (e.g., Hansen and Goheen, 2000). With this understanding of the ecological importance of fungal root endophytes in ecosystems today it is reasonable to anticipate a similar abundance, diversity, and biological impact of fungal root endophytes in ancient plant communities. "
ABSTRACT: A distinctive fungal endophyte, Cashhickia acuminata nov. gen. et sp., is described from permineralized calamite roots from the Upper Pennsylvanian Grand-Croix cherts of France. Heavily infected roots contain numerous intracellular hyphae in the outer cortex that arise from a meshwork-like mycelium extending between cortical cells. All intracellular hyphae are oriented toward the root center; none occur on the inner periclinal host cell walls. Other roots of the same type show localized infection by this fungus in which isolated cortical cells contain or give rise to intracellular fungal growth. Within the cortical cells are host responses in the form of callosities that indicate the roots were alive at the time of infection. Other endophytes are present in the same host tissue but are less frequent. The discovery of this association provides the first detailed account on the morphology of a Carboniferous fungal root endophyte, as well as the spatial distribution within the host, and infection pathways within the cortical tissues.Review of Palaeobotany and Palynology 12/2012; 171:9–18. DOI:10.1016/j.revpalbo.2011.11.009 · 1.66 Impact Factor