Is spontaneous regeneration of raised mire vegetation possible? A case study of the `Czarne Bagno' mire in the Bystrzyckie Hills, southern Poland

Abstract

Research carried out at the `Czarne Bagno' raised mire in the Bystrzyckie Hills range of Poland's Sudety Mountains aimed to determine dynamic trends for the site's peatland vegetation. Present vegetation was therefore characterized. An analysis of plant macroremains from peat cores was used to reconstruct the identity of the past peat-forming plant communities. Several succession stages of vegetation from the time of origin of the peatland through to the present day were indicated on this basis. Ecological indicative values of plant species were also used to determine the palaeohydrological changes experienced. Stages of the development of the tree stand growing on the mire were established from dendrochronology series. Results obtained point to an interruption of the succession of primary vegetation on the peatland around 250 years ago, when today's sparse tree stand of rhaetic pine, Norway spruce and downy birch began to develop. Nevertheless, the last 50 years have brought a reversal of this developmental trend, with elements typical for raised mire returning and the tree stand in retreat. These phenomena seem to have coincided with the onset of peatland drainage, followed by a gradual overgrowing of drainage ditches and consequent re-raising of water level in the mire, respectively.

Drainage ditches enhance forest succession in a raised bog but do not affect the spatial pattern of tree encroachment

“…Peaks in tree encroachment in the 1860’s and the 1940’s can be directly related to the drainage operations being conducted at that time according to historical materials (map of the bog with the locations of the ditches from 1934). Similar processes of increasing the rate of forest succession onto open mires was documented from other locations [ 24 , 28 ]. According to the study by Sarkkola [ 40 ], the number of trees encroaching onto open mires during the first 20 years after drainage operations can double or triple, which stays in line with the phase of intensive tree encroachment detected in Kusowo Bog.…”

“…Increase in the tree cover as the effect of the drainage has been reported in other studies regarding raised bogs in Poland [ 23 ]. In many cases the plausible explanation of intensive tree encroachment is the renewal of drainage system, as it happened in Stążki Baltic bog [ 23 , 26 ] and Czarne Bagno raised bog [ 28 ]. However, records of management activities inspected in archive of Kusowo Bog Manager, available since early 1970’s confirm no drainage operations since that time.…”

“…Drainage breaks this natural cycle of tree establishment and tree dieback allows Scots pine to persist in open mires and eventually turn it into a pine bog forest. Intensified tree encroachment as a result of drainage was reported in numerous studies [ 11 , 19 , 23 – 28 ]. Increase in the tree cover as a result of long-lasting legacy of former drainage human-related disturbances, causes decreasing and withdrawal of the major functions of raised bog ecosystems regarding a water retention and carbon sequestration balance on the landscape level.…”

The colonization history of Scots pine (Pinus sylvestris) in pristine and drained raised bogs in Latvia

“…~6400 km 2 (Pakalne 2008). The development of tree cover has been observed in many ombrotrophic bogs in Latvia during the last century, as has been documented elsewhere in Northern Europe (Linderholm 1999;Ohlson et al 2001;Linderholm, Leine 2004), Central Europe (Frelechoux et al 2000a;Frelechoux et al 2000b;Frelechoux et al 2003;Obidzinski et al 2009), and Canada (Pellerin, Lavoie 2003). As a result of overgrowing, the habitats and plant and animal species typical for raised bogs disappear and the growth and deposition of Sphagnum mosses is reduced, and these factors, in turn, affect the accumulation of carbon in mire ecosystems (Ohlson et al 2001).…”

Natural and Anthropogenic Transformations of A Baltic Raised Bog (Bagno Kusowo, North West Poland) in the Light of Dendrochronological Analysis of Pinus sylvestris L.

“…At least four episodes of drainage took place there, and three of them were recorded in tree-ring width very well (1910s, 1930s, and 1960s). Different growth responses to changes in water level in a peatland (drying and rewetting of peat) in various tree species were noted by Obidziński et al [19]. During peat extraction and the associated low water level, peatland was overgrown by coniferous trees (Pinus rhaetica Brügger and Picea abies), characterized by fast growth, and next also by Betula pubescens Ehrh.…”