Responses of ground vegetation to prolonged simulated acid rain in sub‐arctic pine—birch forest

Abstract

S U M M A R YThe efiects of prolonged simulated acid rain on percentage cover of ground vegetation, and on growth and reproduction of two dominating dwarf shrubs {Empetrum nigrum and Vaccinium vitis-idaea) were examined in a field experiment in the Finnish Subarctic, in an area with low ambient levels of sulphur and nitrogen deposition. Acid rain treatments included moderate (pH 3'8) and high (pH 2-9) concentrations of either H,SO^, or HNO3, or a mixture of them, and were compared with irrigated (pH 6) and dry control plots.Long-term application of acid rain caused significant alteration in the cover and composition of ground vegetation. Effects of acid rain depended on the accompanying anion and on pH. Sub-plots under different canopy tree species differed in responses indicating that spatial heterogeneity is important in predicting the effect of acidifying pollution on this plant community.In the bottom layer, acid rain caused significant reduction in cover of the cyanobacterial lichens Aephroma arcticuw and Peltigera spp. Decrease in cover of fruticose lichens, mainly composed of Cladina spp., more likely resulted from additional watering.In the field layer, acid rain containing moderate concentrations of NO.," caused an increase in cover of graminoid species. There were only slight alterations in growth and cover of the two dominant evergreen dwarf shrubs, E. nigrum and V. vitis-idaea, indicating that these species are tolerant to acid rain of as low as pH 3. Even some positive responses of dwarf shrubs were observed, depending on canopy tree. Application of acid rain of pH 3 to plots under pine trees caused an increase in cover of V. vitis-idaea and, when the nitric acid only was applied, a short-term increase in the number of new shoots of E. nigrum.In contrast to vegetative growth, reproduction of the dwarf shrubs was more strongly affected by acid ram, but this also depended on local conditions and anion composition of acid rain. On 'pine' plots, rain of pH 3 reduced the number of berries and flower buds on terminal current shoot of E. nigrum, however, this was partially compensated by an increase in berr\' production at the ramet level. Simulated acid rain had mainly negati\-e effects on berry production by V. vitis-idaea.

Comparison of five physiological parameters to assess the vitality of the lichen Ramalina lacera exposed to air pollution

“…The decrease of F v /F m ratios, A 435nm /A 415nm ratios and NDVI values in the lichen R. lacera exposed to anthropogenic activity in the study area, is in accordance with studies on the impact of acid rain on lichens ( Hallingbäck and Kellner 1992; Kytöviita and Crittenden 1994; Shevtsova and Neuvonen 1997). The occurrence of acid rain in the study area was already acknowledged.…”

Global change and arctic ecosystems: is lichen decline a function of increases in vascular plant biomass?

“…Scott & Rouse 1995), large‐scale pollution including ‘acid rain’ (e.g. Klein & Vlasova 1992; Gorshkov 1993; Nash & Gries 1995; Shevtsova & Neuvonen 1997) and changing fire frequency regimes (Longton 1988; Landhäusser & Wein 1993) have all been linked with northern lichen physiology or performance but are beyond the scope of this paper.…”

Effects of calcium on seed germination, seedling growth and photosynthesis of six forest tree species under simulated acid rain

“…A significant variation in root growth, but not in shoot growth, was observed. Similarly, Shevtsova and Neuvonen (1997) reported no remarkable changes in shoot growth under acid rain for Quercus rubra in northern Finland. Another study of P. massoniana also Ca effects on germination, growth and photosynthesis under simulated acid rain 409 Figure 3.…”