Draining a peatland rebuilds its fungal community

A peatland stores organic matter because a high water table limits access to oxygen and slows decay. Drainage changes that fundamental property. A study of the Zoige plateau compared sites drained for three and for 48 years, and different water table levels. The team analysed soil chemistry, sequences of bacterial and fungal communities, and microbial activity.

Both the length of drainage and the lowering of the water changed community composition. Fungal structure responded strongly, and in more aerobic conditions the role of some decomposers increased. The authors recorded an increase in some measures of fungal diversity after the water table fell. This is not evidence of improvement. A new community may accelerate the use of old peat carbon and displace organisms tied to a wet environment.

In conservation, the number of taxa has to be separated from the integrity of the ecosystem. A drained site may show more sequences from oxygen-tolerant groups while at the same time losing its carbon-store function, its peat-forming vegetation and its specialists. A single sample will not show the full change; water gradients, depth layers and repeated sampling are needed.

The most important action is maintaining the hydrology of an intact peatland, and in a degraded one, cautious rewetting together with monitoring. Simply blocking a ditch does not guarantee an immediate return of the former community. Fungi should be measured alongside greenhouse gases, plants and water chemistry. A boardwalk and a ban on leaving the route protect the surface, but they will not replace a decision about the whole catchment.

Two sites, not a 48-year experiment

The study compared two Zoige Plateau sites drained for 3 and 48 years, with three water-table positions at each. Sequencing, soil chemistry and activity measurements showed that drainage duration and drawdown changed bacterial and fungal composition; duration explained more variation in fungal communities. Mineral nitrogen shifted, and fungal communities explained more variation in microbial activity than bacterial communities. This does not mean “more fungi” indicate peatland health or that every peatland responds identically. Two sites with different histories are not a 48-year experiment following the same plot, so drainage age may covary with site characteristics. The study did not measure a complete carbon balance or recovery after rewetting.