Predicting edible mushroom productivity using forest carbon allocation modeling and immunoassays of ectomycorrhizae

Carbon Allocation

A variety of factors are known to influence the allocation of carbon below ground. For instance, trees are known to allocate a larger proportion of their NPP below ground on infertile sites than on fertile sites. Much of this allocation goes to mycorrhizal fungi to enhance their ability to obtain nutrients. The same is true of old forests, and of boreal or high elevation forests growing on cold soils, where nutrients are often tightly bound in accumulated organic matter. Drought-related stress can also influence below-ground carbon allocation when trees provide more carbohydrates to roots and mycorrhizae to obtain scarce water. In some cases drought related stress can be influenced by tree size because tall trees experience greater hydraulic resistance moving water to a more distant canopy, while small trees might not fully exploit available soil water.

Most factors that limit tree growth also increase the proportion of NPP allocated below ground. It is possible that mushroom productivity will be significantly correlated with a simple integrative measure of growth constraints such as site index (the ratio of tree height to age), and we will test this possibility. Our hypothesis states, however, that mushroom productivity is correlated with the amount (kg/ha/yr) of NPP allocated below ground, not the proportion. Because NPP is a relatively constant fraction of GPP (see definitions) the quantity of NPP allocated belowground is a function of gross primary productivity as well as proportional allocation of NPP. In other words, although growth constraints cause trees to allocate a greater proportion of their food resources belowground, they have less available food to begin with because they are growing more slowly.

Stand conditions

One of the more important questions we hope to address with our research is how the quantity of food available to mycorrhizal fungi varies across gradients of site fertility, soil temperatures, and stand age.


 Site Fertility

 Stand Age

American matsutake fruiting under snow near Chemult, OR. High edible mushroom productivity values have been recorded in alpine and boreal forests.

Although sand dunes lack fertility, the highest American matsutake (Tricholoma magnivelare) productivity in Oregon has been measured in shore pine (Pinus contorta) forest on Oregon coastal dunes.

Edible ectomycorrhizal mushrooms certainly fruit in old growth forests, but they are typically more abundant in younger stands.


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