What adaptation allows bog plants to live in a bog?

Answer 1

Bogs are highly acid, low nutrient, low-oxygen, water-logged (especially in the lower layers) and, usually, cold. Plants in bogs are severely limited in growth by the lack of available usable nitrogen specifically. Plants have adapted several different ways to compensate for the lack of fixed nitrogen in bogs. Plants that live in Sphagnum bogs are ectomycorrhizal trees (spruce and larch), a variety of ericaceous shrubs, orchids, non-mycorrhizal members of the sedge family, carnivorous plants, and liverworts.

Carnivorous plants adapted leaves to become animal luring traps. They are all apparently non-mycorrhizal, and they obtain most of their nutrients from their prey, rather than the substrate they grow in. They are capable of coexisting when grown near noncarnivorous plants by taking prey as a nitrogen source and avoiding competition. If they do not catch prey they do not grow larger even given sunlight, being limited by lack of nitrogen for amino acid/protein synthesis.


Alders, bog myrtle and others adapted their roots for a symbiotic relationship with Frankia, a class of nitrogen fixing Actinomycete bacteria that live in actinorhizal nodules.

Then spruce, larch, orchids and varieties of ericaceous shrubs have mycorrhizae, fungal symbionts capable of extracting combined N and P from organic substrates in exchange for the products of photosynthesis. Wetland mycorrhizal associations help plants in soils with restricted nutrient access.
Arbuscular mycorrhizal fungi (AMF) associate with 58% dicots vs 13% monocots
AMF <10% in both cattails & sedges
Dark Septate Endophytic fungi (DSE) associate 9% dicots vs 24% monocots
http://cat.inist.fr/?aModele=afficheN&cp...

A few, like sedges, can scavenge amino acids from the soil directly by secreting enzymes from the roots to digest nitrogen bearing proteins from the organic matter in the soil. The roots then take up the free amino acids and other nitrogen bearing compounds.

Bog soil is deficient in nutrients because anaerobic ammonifying & decomposing bacteria, which recycle nutrients by causing organic detritus to decay, cannot perform well in the acidic conditions of most of the bog. Plants rely on the activity of these organisms in other soil types.

These regions are largely non-mycorrhizal because aerobic mycorrhizal fungi also have trouble persisting in these systems but due to lack of oxygen. The lack of aerobic ecology limits all the most active bacteria leaving the less active anaerobic diazotrophs, like Frankia, to supply fixed nitrogen because they live inside root nodules in association with the plants.