Vegetation responses to long‐term alkaline cement dust pollution in Pinus sylvestris‐dominated boreal forests – niche breadth along the soil pH gradient

Abstract

Questions: How resilient is boreal forest vegetation growing on acidic podzols to the environmental change caused by alkaline kiln dust pollution? How adaptive is the vegetation, when species pool and time for dispersal do not limit? How constant is the species niche breadth along the soil pH gradient?Location: Region of 30 km around the Kunda cement plant, northern Estonia (59°30′ N, 26°32′ E), which has been continuously polluted last 140 years. Methods:We sampled 20 forest stands on sandy gleyic podzols at various distances from the pollution source, leeward and windward of prevailing winds. Data processing: principal components analysis for gradient generalization, indicator species analysis for grouping species along the pollution gradient and generalized linear model analyses to estimate species reaction to pollution, considering covariates.Results: The impact of alkaline dust accumulated over a century persisted despite resolute reductions of pollution. Forest soil conditions changed 10 km leeward and 5 km windward from the source: the litter pH level changed from 3.6 to 4.5 in unpolluted forests to 7.1-7.4 in the heavily polluted forests, and soil Ca content increased ten-fold. Soil alkalization has induced a remarkable succession from typical boreal vegetation toward vegetation of boreo-nemoral or calcareous habitats. We detected a linear increase of species richness from habitats on acidic soils (unpolluted) to newly formed alkaline soils (polluted habitats), reflecting the species pool composition and size, which is known to be large for calcicolous species. The establishment of several endangered calcicolous species shows the lack of dispersal limitation and points on their narrow soil pH niche. The niche breadth of species along the pH gradient varied among species, but only a few species appeared to be pH generalists.Conclusions: Species ranking along the pH and/or Ca gradients indicates (1) the existence of different ecological guilds in terms of ecological niche use, and (2) the formation of a new community is dictated by the tolerance level of each species. This supports the individualistic community assembly rule suggested by Gleason. We find that such polluted regions with disturbed communities have high scientific value as long-term ecological experiments, but this might lead to conflict between the peculiar biodiversity complex and human well-being.

Trentepohlia umbrina on Scots pine as a bioindicator of alkaline dust pollution

“…Auerbach et al, 1997;Paal et al, 2010); at the same time several plant and lichen species can be found in the habitats where they normally do not grow (e.g. Marmor et al, 2010;Paal et al, 2013). Fine dust particles also pose a threat to human health, and can lead to respiratory and cardiovascular diseases (World Health Organization, 2013).…”

Community response to alkaline pollution as an adjusting re‐assembly between alternative stable states

“…; Martin & Nilson ) and intense pollution near the plant caused the ‘nemoralization’ of the boreal forest community (Paal et al. ).…”

“…The study was performed in the region surrounding the town of Kunda (59°30 0 N, 26°32 0 E) in northern Estonia on the southern coast of the Gulf of Finland. The area within 50 km around the town hosts a diverse meta-pool of lichen species, as the region encompasses a high diversity of habitats from pine-dominated boreal and broadleaved nemoral forests (J€ uriado et al 2009;Paal et al 2013), and various soil types, fragments of sandstone and limestone escarpment (Raukas 1995).…”

“…(Mandre et al 2000; Heidelberg Cement Sustainability report 2007, http://www.heidelbergcement.com/NR/ rdonlyres/E4F7B3FD-FAA3-414D-A70E-98D344D0FBA1/ 0/HCNESustainabilityReportwebversion.pdf). During the period of intensive production and before the installation of dust-removing filters (1970s to early 1990s) signs of dust pollution were detected over a few tens of kilometres (Mandre et al 1992;Martin & Nilson 1992) and intense pollution near the plant caused the 'nemoralization' of the boreal forest community (Paal et al 2013).…”

Regional differences in soil pH niche among dry grassland plants in Eurasia

“…Soil pH stands out as one of the most important edaphic predictors of plant species occurrence (Dupré and Ehrlén , Paal et al ). Although not a primary resource, it is regarded as a ‘master variable’ (Baar and Roelofs ) due to its control over the plant‐availability of nutrients and the presence of toxic cations (e.g.…”