Encroachment of woody species on a drained transitional peat bog in ‘Mszar Bogdaniec’ nature reserve (Western Poland)

Abstract

One of the most important threats for open peat bog ecosystems is encroachment of woody species, which causes transformation of habitat conditions and leads to retreat of specialised species. Drainage increases the rate of succession. The aim of study is the assessment of human-accelerated succession in a transitional bog. The study was conducted in ‘Mszar Bogdaniec’ nature reserve (W Poland). The structure of vegetation and tree stands was described and compared using ordination methods. Near the peat bog border, tree stands of Betula pubescens developed. Towards the middle part of the peat bog, the number, cover and height of trees decreased. The central part of the peat bog was covered by Sphagno recurvi–Eriophoretum vaginati in dryer parts and Sphagno recurvi–Eriophoretum angustifolii in wetter parts. The study showed that the successional sequence in these conditions differs from the classical bog succession scheme. Despite high propagule pressure of Pinus sylvestris, the most important woody species was B. pubescens, which performed better than other species. Erechtites hieracifolia, an alien invasive herb species, which previously was rarely recorded in bogs, appeared when the bog was dried by drainage. In this study, it reached high frequency and abundance, which shows that it may be a next serious threat to disturbed wetland ecosystems.

Peatland degradation: The relationship between raised bog hydrology and normalized difference vegetation index

“…The significance of relations between the WT and the production of bryophytes and shrubs in bog communities has been reported in other previous studies (Weltzin, Harth, Bridgham, Pastor, & Vonderharr, 2001). Therefore, the links between NDVI and WTD that were confirmed in our research (by the strong positive correlation between NDVI avg-c and WTD; r = .74, p < .01 compared with W2, r = .64, p < .05 compared with W3) enable NDVI to be ; increased colonization by woody vegetation is in agreement with the tendencies in other European countries (Dyderski et al, 2015;Frelechoux et al, 2003;Smiljanić et al, 2014). However, the lack of hydrological monitoring data may impede the detection of degrading wetland areas or constrain it to a limited area, restricting the possibility of viewing the overall situation of the wetland complex.…”

“…Increased colonization by woody vegetation is reported from multiple peatland complexes in Europe (Dyderski, Gdula, & Jagodziński, 2015;Frelechoux, Buttler, Gillet, Gobat, & Schweingruber, 2003;Smiljanić et al, 2014). Short-term measurements, cartographic analysis, and visual observations confirm the same tendencies are occurring in Lithuania.…”

Do understorey or overstorey traits drive tree encroachment on a drained raised bog?

“…Low densities of P. sylvestris natural regeneration in birch peatland forests on drained peatland confirm our previous findings (Dyderski et al . ). In the cited paper we connected low P. sylvestris densities to strong competition with herbaceous plants, especially Molinia caerulaea and Eriophorum vaginatum , which benefit from peatland drainage through increased nitrogen availability (Limpens et al .…”

“…; Dyderski et al . ). Semi‐natural forest can develop within a relatively short time after drainage, further accelerating dehydration by increased evapotranspiration (Fay & Lavoie ; Sarkkola et al .…”

“…Despite the paper of Dyderski et al . (), in which human‐accelerated woody species encroachment in the ‘Mszar Bogdaniec’ transitional bog was described (based on vegetation structure, tree stand features and densities of natural regeneration of woody plant species throughout the drained mire), there is a clear lack of quantitative assessment of natural tree regeneration in wetlands, as previous studies concerning encroachment of woody species into wetlands have focused mainly on vegetation analyses ( e.g . Laine et al .…”