Of course, in the long-term perspective rewetting of peatlands has the potential to fulfil the multiple restoration goals including those targeting on climate, water, and species protection. However, in particular if long-term drained and agricultural used sites are rewetted often shallow lakes are formed due to peat loss and soil shrinkage. Such inundation could be problematic if areas are affected which still have a higher conservation value due to occurrence of rare orchids or butterflies like Euphydras aurinia. Such a case seems to be an exception but indeed such remnants can be occasionally found in larger drained riparian peatlands located in depressions or other areas which were less affected by drainage measures. Is there any publications available reporting on (non-intended) negative consequences on biodiversity due to rewetting measures?
Dominik Zak
Dear Dr. Zak, this is an interesting question. In my view, the shift in the soil environment from aerobic to anaerobic could trigger a dramatic change in soil biology and soil chemistry. Likewise, plant species that do not thrive under poorly drained conditions will be replaced by those that grow well under such conditions.
Dear Victor,
many thanks for sharing your thoughts. I fully agree that there is a drastic change in soil conditions and we know that that the succession toward lost peat-forming plant species can be retarded over long-time even decades depending on many factors like ongoing high nutrient levels, missing seed bank or as mentioned inundated conditions. Indeed I am talking about the possibility that even under drained conditions in some remnant areas some valuable peatland species survived since environmental conditions where still favorable. I found such situation in two long-term drained peatlands and in one peatland upon rewetting the last population of a rare butterfly died off since the habitat with "host plants" (Scabiosa succisa L.) became fully inundated. I was searching the literature to find other examples without any success so far :- ((!
BWD
Peatlands are strategic areas for climate change mitigation because of their matchless carbon stocks. Drained peatlands release this carbon to the atmosphere as carbon dioxide (CO2). Peatland rewetting effectively stops these CO2 emissions, but also re-establishes the emission of methane (CH4).
https://www.nature.com/articles/s41467-020-15499-z#:~:text=Peatlands%20are%20strategic%20areas%20for,of%20methane%20(CH4).
Dear SJ Malik,
I can understand your point very well. Indeed from strategic reasons the climate issue can be set as priority in particular for large degraded peatland sites. The benefit can be enormous if you take into account that the annual release of carbon dioxide from drained peatlands can be up to 30 t CO2-C/ha. Even if accelerated methane emissions might overwhelm to some extent the strongly reduced carbon dioxide emissions from inundated peat soils at first glance as nicely elucidated in the suggest work. In turn, I fully agree that biodiversity restoration targets are mostly relevant for smaller less degraded areas. Still it might be valuable to take also biodiversity issues into account for larger drained peatland areas in particular if highly-endangered species can be found in some "remnant areas". Such areas could be eventually also a valuable step stone upon rewetting of the other highly deteriorated peatland area, however this might be too illusory?!
BWD
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