Marshes, bogs, and marshy areas: which mushrooms grow in moist soil?

Introduction to wet ecosystems: marshes, bogs, and wetlands

What marshes are and how they form

Marshes are wetlands characterized by the presence of stagnant or slow-moving water, with predominantly herbaceous vegetation. They form in land depressions where water accumulates, creating anaerobic conditions that influence the decomposition of organic matter. This process leads to the formation of peat, a partially decomposed organic material that acidifies the soil. The acidity and constant moisture create a unique environment for specialized fungal species, which have developed specific adaptations to thrive in these conditions.

The formation of bogs and their ecological importance

Bogs are a particular type of wetland where peat accumulates, formed from partially decomposed plant material under conditions of acidity and anaerobiosis. These ecosystems are crucial for climate regulation, as they sequester large amounts of carbon. The mycology of bogs is particularly interesting because it hosts fungi not found in other habitats. The incomplete decomposition of organic matter offers unique resources for saprotrophic fungi, while symbiotic relationships with plants typical of these environments, such as mosses of the genus Sphagnum, support specialized mycorrhizal fungi.

Wetlands: characteristics and distribution

Wetlands include a variety of environments, from temporary marshes to the shores of lakes and rivers. They are characterized by fluctuating water levels, which create dynamic conditions for fungal life. Fungi in these areas must adapt to periods of submersion and exposure to air, developing strategies such as producing resistant spores or symbiosis with aquatic plants. Fungal diversity in these areas is influenced by seasonality and the availability of specific substrates, such as submerged wood or roots of marsh plants.

Marsh fungi: adaptations and representative species

Lignicolous fungi of marshes: specialized decomposers

Lignicolous fungi are those that grow on wood, decomposing it and recycling nutrients. In marshes, submerged or partially submerged wood provides an ideal substrate for species such as Xylaria longipes, which fruits on decaying branches and trunks. This fungus, with its characteristic club-shaped and blackish appearance, is common in many temperate wetlands. Another interesting species is Pholiota alnicola, which grows on alder trees, typical of marshes. These fungi produce enzymes capable of degrading lignin and cellulose even under low oxygen conditions, contributing significantly to the carbon cycle.

Mycorrhizal fungi of marshes: symbiosis with marsh plants

Mycorrhizal relationships are crucial in nutrient-poor environments like marshes. Fungi such as Lactarius trivialis form mycorrhizae with trees like willows and birches, helping them absorb water and nutrients in exchange for carbohydrates. This symbiosis is particularly important in acidic, water-saturated soils where the availability of phosphorus and nitrogen is limited. Other fungi, like Russula paludosa, are specific to conifers in acidic bogs. These relationships are so specialized that some marsh plants, such as orchids, depend on mycorrhizal fungi for seed germination and growth.

Parasitic and pathogenic fungi in wet environments

Parasitic fungi also find a favorable environment in marshes, exploiting plants stressed by extreme conditions. Armillaria mellea, for example, can attack trees weakened by stagnant water, causing root rot. Similarly, Phytophthora spp., although oomycetes and not true fungi, are important pathogens in these areas, causing diseases like root rot in various plant species. Understanding these dynamics is crucial for the conservative management of wetlands.

Illustrative tables on fungal biodiversity in marshes

Table 1: distribution of fungal genera in relation to wetland type and pH

Source: "Fungal Diversity in Wetlands" (2018)

Statistics on fungal richness in relation to soil moisture

Recent studies have shown that fungal richness in marshes peaks at soil moisture levels around 80-90%. Above or below this range, diversity decreases due to drowning or desiccation stress. The following table summarizes data from a study conducted in temperate bogs:

Table 2: fungal richness in relation to soil moisture in temperate bogs

Source: Smith et al. (2020) "Fungal responses to moisture gradients in peatlands"

Edible and toxic fungi of wetlands: a recognition guide

Edible fungi of marshes: didden delicacies

Among the edible fungi of marshes, Cantharellus luteocomus stands out, a species typical of sphagnum bogs, with an orange cap and a slender stem. This mushroom, with its fruity flavor, is sought after by gourmets but must be harvested carefully to avoid damaging the delicate ecosystem. Another prized mushroom is Leccinum versipelle, which grows under birches in wet areas, recognizable by its orange-brown cap and stem covered in black scales. Its firm, flavorful flesh makes it ideal for drying.

Toxic and deadly fungi: the dangers of wetlands

Marshes also host dangerous fungi, such as Galerina paludosa, a deadly mushroom that grows on mosses in bogs. This small brown mushroom contains amatoxins, the same as the deadly Amanita phalloides, and can be mistaken for edible species by inexperienced foragers. Another toxic fungus is Cortinarius rubellus, typical of acidic bogs, which causes kidney failure. Its resemblance to other edible Cortinarius makes careful microscopic identification essential.

Recommendations for sustainable harvesting

Mushroom harvesting in marshes must be conducted with extreme caution to preserve these fragile ecosystems. It is recommended to: limit harvesting to personal quantities, avoid damaging the underground mycelium, and not harvest rare or endangered species. In many areas, bogs are protected, and harvesting may be regulated or prohibited. Always consult local authorities before venturing into these environments.

Scientific research and curiosities about marsh fungi

Bioluminescence: fungi that glow in the dark

Some fungi of marshes, like Armillaria mellea, are bioluminescent, emitting a greenish-bluish light in the dark. This phenomenon, due to enzymatic reactions involving luciferin, might function to attract dispersing insects or for metabolic regulation. On humid nights, logs colonized by these fungi offer a magical spectacle, though rare to observe.

Adaptations for spore dispersal in aquatic environments

Fungi of marshes have developed innovative strategies for spore dispersal in water-saturated environments. Some species produce spores with hydrophobic appendages that help them float, while others hitch rides on aquatic insects for transport. Xylaria aquatica, for example, produces spores that only germinate after floating for a period, ensuring the colonization of new substrates.

Historical and cultural curiosities about marsh fungi

Historically, marsh fungi have had interesting uses. Some native cultures used Daldinia concentrica, a common woody fungus in wetlands, as tinder for fire due to its ability to burn slowly. Other fungi were used in dyeing or traditional medicine, though with caution given the toxicity of some species.