Standing Crop and Animal Consumption of Fungal Sporocarps in Pacific Northwest Forests

Abstract

Although fungal fruiting bodies are a common food supplement for many forest animals and an important dietary staple for several small mammals, changes in their abundance and consumption with forest succession or disturbance have not been quantified. Above-and belowground fungal fruiting bodies (epigeous and hypogeous sporocarps) were sampled for 46 mo in managed-young, natural-mature, and old-growth western hemlock (Tsuga heterophylla) stands in Washington State. Screen exclosures were placed over the surface of half of the sample plots to prevent aboveground predation of sporocarps. Standing crop of epigeous sporocarps was low in most seasons and then increased 30-fold to a mean of 2.28 kg/ha in the fall. Epigeous biomass varied little between stand types, and animal consumption of these sporocarps was low. Standing crop of hypogeous sporocarps was 0.78 kg/ha in managed-young stands, compared to 4.51 and 4.02 kg/ha in natural-mature and old-growth stands. In all stands, standing crop peaked in the summer and was lowest in the winter. Mean animal consumption of hypogeous sporocarps was 0.64 kg/ha, a value that exceeded the available standing crop quantity of 0.36 kg/ha in managed-young stands during the winter. In natural-mature and old-growth stands, truffle biomass remained high year-round and exceeded consumption in all seasons. Low hypogeous sporocarp biomass in the managed-young stands resulted from the general absence of large clusters of Elaphomyces granulatus, which made up Ͼ90% of the biomass in older stands. This absence in managed-young stands may be associated with the thin organic layer that has developed following harvest and burning 60 yr ago. The consistent level of animal consumption indicates that truffles may be an important and readily available year-round food source, compared to the ephemeral fruiting of epigeous sporocarps. Changes in forest composition and age due to natural disturbance or human management influence fungal sporocarp productivity and diversity and, consequently, affect food availability for animals dependent on hypogeous sporocarps.

Is rarity of pinedrops (Pterospora andromedea) in eastern North America linked to rarity of its unique fungal symbiont?

“…Attempts were made to locate sporocarps in the field sites, but none were recovered. This was not surprising due to the hypogeous nature of the sporocarp, sporadic fruiting, removal of most sporocarps by mammals (North et al 1997) and the putative rarity of this species in eastern forests. This fungal species was not frequent in the soil spore banks of eastern white pine forests with or without pinedrops, but was less frequent in the latter.…”

Truffle abundance and mycophagy by northern flying squirrels in eastern Washington forests

“…We sampled soils for truffles using the same size and number of plots as the methodology of Luoma et al (1991), which has been adopted by others for comparative studies (North et al, 1997;Waters et al, 1997;Smith et al, 2002). We systematically located 25 4 m 2 circular plots 40 m apart on an 8 Â 8 or 7 Â 9 grid used for trapping flying squirrels.…”

“…Much is known about EMF diversity (Fogel and Trappe, 1978;Luoma et al, 1991;North et al, 1997;Colgan et al, 1999;Smith et al, 2002) and rodent mycophagy (Fogel and Trappe, 1978;Maser et al, 1986;Carey, 1995;Carey et al, 1999) in wet Douglasfir forests in the Pacific Northwest (PNW) west of the Cascade Range crest. Others have studied relatively mesic mixed-conifer fir forests in the interior West Rosentreter et al, 1997;Currah et al, 2000;Pyare and Longland, 2001); but, there is scant data for dry low-elevation forests dominated by ponderosa pine (Pinus ponderosa), dry Douglas-fir (Pseudotsuga menziesii), or dry grand fir (Abies grandis) plant associations outside of Arizona (States and Gaud, 1997).…”

“…As host tree species change in dominance among the types, associated EMF assemblages should also differ (Molina et al, 1992;Carey, 1995;States and Gaud, 1997;Massicotte et al, 1999). Moreover, EMF species richness and abundance increase with canopy cover (Amaranthus et al, 1994;States and Gaud, 1997), stand density in general (North et al, 1997;Colgan et al, 1999), or with increasing amounts of litter and woody debris (Amaranthus et al, 1994;Clarkson and Mills, 1994;North and Greenberg, 1998).…”

Spore Dispersal of Fetid Lysurus mokusin by Feces of Mycophagous Insects

“…Furthermore, we found that the sticky gleba of L. mokusin was rarely attached to the body of A. maritima, in accordance with the hypothesis that Dictyophora spores are largely dispersed via guts of visitors rather than by adhering to insect bodies (Tuno, 1998). Advantages of spore dispersal by animals may include extension of dispersal range, access to new nutrient sources, and enhancement of gamete transfer for mating (Ingold and Hudson 1993;North et al 1997;Steinebrunner et al 2007). We found that L. mokusin provides food in the form of gleba to the earwig A. maritima, which may excrete about 1.18×10 7 spores of L. mokusin per day (far more than the numbers, ca.…”