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19.08.2021
Skadi Menne
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App­li­ca­ti­on of Spha­gnum mosses

A field report from the Uni­ver­si­ty of Heidelberg

One of our first cus­to­mers to recei­ve Spha­gnum mos­ses for sprea­ding from our Sus­taina­bi­li­ty Team was the Uni­ver­si­ty of Hei­del­berg. In the bota­ni­cal gar­den of the Ruprecht-Karls-Uni­ver­si­ty, a peat moss basin was estab­lis­hed in 2019/2020. Mr. Andre­as Franz­ke, who is respon­si­ble for the pro­ject, gave us an over­view of the cur­rent sta­tus in an interview.

Kpoint: Hel­lo Mr. Franz­ke, thank you very much for taking the time. How lar­ge is your peat bog area and how can we ima­gi­ne the con­struc­tion of the area?

Andre­as Franz­ke: The basis of the plant is a sea­led con­cre­te basin, which mea­su­res approx. 15 x 9 meters and has a depth of 0.5 meters. The base is made up of inver­ted PE plastic boxes that have been dril­led through and now ser­ve as a water reser­voir for the peat body. The boxes are pla­ced at a distance of 10 cm from each other. Coar­se white peat was pla­ced on top of the boxes and in the spaces bet­ween them. On top of this, two hig­her, rela­tively lar­ge bulk are­as were mode­led with fine white peat.

In this lay­er abo­ve the boxes the peat body is about 20 to 25 cm thick and the bulbs have a total thic­kness of about 50 cm. The struc­tu­re was then allo­wed to sett­le for about 9 mon­ths befo­re the area was plan­ted. In the midd­le we have what is cal­led the „bog eye”, which is a com­ple­te­ly free area fil­led with water. This was edged with peat bricks to pre­vent the edges from slip­ping and to keep the bog eye clear.

Ska­di Men­ne: How was the Spha­gnum moss spread?

Andre­as Franz­ke: The Spha­gnum mos­ses were even­ly dis­tri­bu­t­ed on the mode­led peat lay­er and pres­sed on a litt­le. Over the win­ter, the area was cove­r­ed to pro­tect it not only from the cold, but also from the leaves.

Ska­di Men­ne: How have the mos­ses we sup­plied developed?

Andre­as Franz­ke: The Spha­gnum mos­ses have deve­lo­ped posi­tively throughout. In addi­ti­on, the fol­lowing spe­ci­es have emer­ged from the soil seed bank: ‚Midd­le Sun­dew’, ‚Round-lea­ved Sun­dew’ and ‚Bell Heath’. The­se have all beco­me firm­ly estab­lis­hed in the plant and are forming good stands. Tha­t’s also exact­ly what we wan­ted to achieve.

Ska­di Men­ne: What kind of irri­ga­ti­on sys­tem do you use?

Andre­as Franz­ke: The basin does not have a drain. So irri­ga­ti­on is done exclu­si­ve­ly by rain­wa­ter. On days without rain, the basin is irri­ga­ted once or twice via cir­cu­lar sprink­lers with rain­wa­ter from a cis­tern, an under­ground or cove­r­ed collec­tion tank.

Ska­di Men­ne: Loo­king back, what expe­ri­ence have you gai­ned in plan­ning, crea­ting and main­tai­ning the area?

Andre­as Franz­ke: One important point is the remo­val of any weeds. So that we can dis­tri­bu­te the weight even­ly during remo­val and not lea­ve any per­ma­nent imprints in the soft sub­soil, we have laid out a lad­der as a foot­bridge, with a board as a sup­port. This pre­vents com­pac­tion of the peat bodies.

Some of the plants that belong in the sys­tem must be regu­lar­ly redu­ced in popu­la­ti­on or replan­ted in the desi­red are­as of the peat­land. ‚Bell hea­ther’ and ‚blue moor grass’, for examp­le, are so vigo­rous in growth that we have to „trap” them regu­lar­ly. More deman­ding spe­ci­es, such as ‚Midd­le Sun­dew’ or ‚White Beak Reed’, on the other hand, have alrea­dy beco­me firm­ly estab­lis­hed in the desi­gna­ted places.

When it rains too much, the water level has to be lowe­red by means of a sub­mer­si­ble pump. This is time-con­suming, as the pump regu­lar­ly beco­mes clog­ged. Pro­bab­ly an adjus­ta­ble drain would be good to avoid clog­ging in the future. In win­ter, the water level is not regu­la­ted. Too high water levels in the win­ter will result in drow­ning of unwan­ted weeds in the low are­as. We have not yet obser­ved any dis­ad­van­ta­ge for the bog plan­ting in this context.
In retro­spect, the plan­ting of the rai­sed bog basin has actual­ly deve­lo­ped as plan­ned. Sin­ce we had no pre­vious expe­ri­ence in this area, this is of cour­se par­ti­cu­lar­ly gra­ti­fy­ing for us.

Ska­di Men­ne: Thank you Mr. Franz­ke for taking the time for this interview!

If you should ever visit Hei­del­berg, you can of cour­se visit the Bota­ni­cal Gar­den at any time. You can then see on site how well our Spha­gnum mos­ses have deve­lo­ped, and you will find even more infor­ma­ti­on about the instal­la­ti­on there.

(Pho­tos: S. Elf­ner Bota­ni­scher Gar­ten Uni­ve­ri­ty of Heidelberg)