Human Impact on Water Circulation Patterns in Raised Bogs of the Baltic Type, Northern Poland

Abstract

Raised bogs of the Baltic type are unique because of their geomorphologic structure and hydrologic conditions. There are about 80 bogs of this type in Poland. All are affected by human impact, and their water circulation patterns are disrupted by artificial outflows. The aim of the study was to show the effects of human impact on water circulation patterns in raised bog on an example of the Wielkie Bagno peat bog. The main work consisted of field studies, during which measurements of groundwater fluctuations, flows at main outflows, and hydrographic mapping were performed. Data on precipitation and evaporation were also obtained from state institutions. Research has shown that fluctuations in groundwater levels in the Wielkie Bagno bog average 78 cm per year (hydrological years 2018–2019) and the bog is in poor condition. This is mainly due to climate change, which manifests itself in too little precipitation in summer and an increase in evaporation, a too dense drainage network causing the lowering of the groundwater level in the peat bog, and the close proximity of a peat mine causing significant drainage of water from the examined peat bog, as well as too large fluctuations of groundwater during the year and in individual months. In some areas, a near-surface layer of the bog was also detected, about 30 cm thick, which is a sign of bog desiccation (especially in summer). Water balance data were used to show that the quantity of water available in the bog is determined by atmospheric precipitation, which is too small in the warm period. As a consequence, there are months with a negative climatic balance. It was also observed that factors such as physical location in different parts of the bog and the degree of degradation also affect water circulation patterns in the study area. At the moment, the most important task in the peat bog is to raise the groundwater level, reduce its fluctuations, and reduce human pressure on the bog.

Use of the Gas Emission Site Type Method in the Evaluation of the CO2 Emissions in Raised Bogs

“…In connection with the functions they perform for the environment, it is very important to protect peatbogs, especially since they are one of the fastest-disappearing ecosystems in our climate zone. They are subject to progressive degradation due to changes in hydrological conditions, mainly as a result of numerous drainage and land use changes [78,79]. This statement is supported by the research of Xiao et al [80] on the eutrophic Lake Taihu.…”

The use of the GEST method to estimate greenhouse gases uptake or emissions in the absence of data for a raised bog

“…According to studies by Panai et al (2017), carbon accumulation was at times larger during wetter and warmer conditions when Sphagnum was dominant, and smaller during periods of mixed Sphagnum and vascular plant (mainly sedges) growth under drier/unstable hydrological conditions. Currently, there is an increase in the number of dry periods, which is directly related to climate change, and it has caused extreme weather phenomena and required human intervention (Mikhaylov et al, 2020;Lipińska et al, 2023). It is also vital that peat bogs function based on an hydrological equilibrium that may be easily disturbed by drainage works and overall changes in water circulation patterns (Haapalehto et al, 2011).…”