Sphagnum Bogs: A closer look at why we need them

By Hannah Weiss, University of Vermont

Photos by Adam Spencer

The sphagnum (Sphagnum magellanicum)-dominated bog (>3km by >3km) we explored existed in a depression in the landscape, likely an old river floodplain of the Vargas River that flows east to west towards Tortel. The bog likely formed over thousands of years as water collected in the valley, and is maintained by a high water table.

The expansive wetlands of the Sphagnum bog we studied

We set up twelve transects within a 2km by 2km square within the bog and we monitored four of these transects – transect 2, 5, 7, and 8. Along each transect we marked out five locations 10m apart to analyze plant and lichen species composition as well as relative water depth (to the top of the monitoring wells) and relative sphagnum depth (to be monitored and compared annually). Within each of these five locations, we measured a 1m by 1m area to analyze species composition. Both uprooted and unmarred sphagnum dominated these five plots while murtilla (Empetrum rubrum), chaura (Gaultheria mucronata), Caryx microglochin, and snags of cypress (Pilgerodendron uviferum) were common. Other grammanoids (Juncus sp., Caryx magellanica,), lichens (Usnea spp.), and other plants (Nothofagus dombeyi, Myrteola nummlaria, Gaultheria antartica) were either scattered or rarely found within these plots. All of these species were found within and near the harvested section along the south side of the road towards Tortel, while these along with others, were found along the outside and less disturbed area of the bog. Occasional Fio Fio (Elaenia albiceps), Thorn-Tailed Rayadito (Afrastura spinicauda), and Chucao Tapaculo (Scelorchilus rubecula) were heard and seen along the edge of the bog within the nearby Coigue (N. dombeyi) forest.

Murtilla (Empetrum rubrum) berries thrive in the moist habitat of the Sphagnum bog.

Undisturbed sphagnum appeared red while in the sun and mat-like. It gave, if one applied pressure, to reveal long (8cm) fibers that descended further into the bog. The color changed from a dull red to a decaying yellow-tan look beneath the surface, and in places, the fibers and decaying fibers extended ~45cm below the surface. Murtilla and chaura both were low-growing (up to 10cm in height) small stalks – murtilla contained small needles and chaura contained small spade-shaped leaves with a point at the tip. Caryx microglochin was a low-growing, pale green grass that contained a brown, pointed fruit at the top. The cypress snags were stumps bleached by the sun and the possible result of harvesting.

Undisturbed Sphagnum habitat with islands of Cypress trees.

The bog contained some N. dombeyi forests along the road and surrounding the edge when elevation began to increase, yet the only tall (above 2m) species within the bog were either dead or alive cypress trees. Otherwise the bog was open and received constant, direct sunlight when the sun shone. The days we spent there, the weather was a mix between partly cloudy (50-90% cloud cover) and almost full sun (<10% cloud cover). The wind speed ranged from 1-3. The bog itself was extremely wet – the water table, in many places, was <10cm from the surface and merely stepping on the bog would result in one’s entire foot becoming instantly sodden. The water table became higher the farther we moved south away from the road, as seen from our water table readings on our two sampling days.

This sphagnum bog provides several ecosystem services, including acting as a carbon sink (through slowing the decomposition of organisms that fall into the bog), a water purifier, erosion control, flood mitigation (through providing a saturated area for water to exist in without flowing through quickly), food source (berries rushes, mushrooms can grow), as well as an economic resource.

Aerial surveillance adds to analyze the amount of habitat already harvested.

Sphagnum is used as a commercial product (ie. gardening activities, diapers) and Chile is one of its main exporters. Thus, the harvesting of sphagnum is a lucrative way to spend the summertime – the Chilean sphagnum harvest has occurred for at least the past 30 years. There were four harvesters from several different parts of Chile working on the site we were monitoring and to them, sphagnum was a solid way to make money – one, Marcelo, said that he’d been harvesting for the past 10 years while another, Diego, said that this was his first summer harvesting. Interestingly, none of the four workers were from the closest town, Tortel. This demographic note is interesting because Tortel used to base their economy on cypress extraction and trade, however the trade is dwindling (according to our research instructor, Kayla). Sphagnum could be the next extractive activity for those who have lost material to trade from lack of cypress. According to Marcelo, their extraction process is sustainable – they harvest only 10cm deep and rotate this in a cycle, which allows for 5 years of grow-back time. Thus far, from drone footage, it appears only 1% of the bog has been harvested (since October, 2016) and if the workers actually withhold the 5-year cycle situation, perhaps it can be done in a sustainable way.

Sphagnum harvesting reveals the moss’s long, spongy tendrils.

The effects of the harvest on the bog are still being researched. However, from my observations, once the bog is trampled it becomes more sodden and harder to walk through. The patches that have been harvested are yellowing and the plants growing in the bog have been disturbed as well. It’s not clear whether the water level change (increasingly higher as one moves away from the road) is a result of the harvest or the result of the road. It’s also not clear whether the sphagnum’s regeration is negatively impacted by the alleged 5-year-cycle of growing. On Chiloé Island, the harvest was done unsustainably and now parts of the population has lost access to the water resources they once held – hopefully the harvest here can be completed in a better way.

Maya Morduch-Toubman (Bowdoin College) and Hannah Weiss (UVM) measure plant associations within a plot of harvested Sphagnum.

More research and monitoring, as well as a hopefully sustainable extraction process is all necessary to ensure the bog’s ecosystem services remain intact.

Species List: