Shevtsova A, Neuvonen S
Department of Biology, University of Turku, FIN-20014 Turku, Finland.
Kevo Subarctic Research Institute, University of Turku, FIN-20014 Turku, Finland.
New Phytol. 1997 Aug;136(4):613-625. doi: 10.1046/j.1469-8137.1997.00782.x.
The effects of prolonged simulated acid rain on percentage cover of ground vegetation, and on growth and reproduction of two dominating dwarf shrubs (Emapetrum nigrum and Vaccinium vaitisidaea) 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 HNO , 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 ram 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 Nephroma arcticum 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, Enigrum 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 I, 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 rain, 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 berry production at the ramet level. Simulated acid rain had mainly negative effects on berry production by V. vitis-idaea.
在芬兰亚北极地区进行的一项田间试验中，研究了长期模拟酸雨对地面植被覆盖百分比以及两种优势矮灌木（黑果岩高兰和越桔）生长和繁殖的影响，该地区硫和氮的环境沉降水平较低。酸雨处理包括中等浓度（pH 3.8）和高浓度（pH 2.9）的硫酸、硝酸或它们的混合物，并与灌溉（pH 6）和干燥对照地块进行比较。长期施用酸雨导致地面植被的覆盖度和组成发生显著变化。酸雨的影响取决于伴随的阴离子和pH值。不同树冠树种下的子地块反应不同，这表明空间异质性在预测酸化污染对该植物群落的影响方面很重要。在底层，酸雨导致蓝藻地衣北极肾盘衣和皮果衣属的覆盖度显著降低。主要由石蕊属组成的灌丛地衣覆盖度的降低，更可能是由于额外浇水所致。在草本层，含有中等浓度硝酸的酸雨导致禾本科植物的覆盖度增加。两种优势常绿矮灌木黑果岩高兰和越桔的生长和覆盖度仅有轻微变化，这表明这些物种能够耐受低至pH 3的酸雨。甚至还观察到矮灌木有一些积极反应，这取决于树冠树种。在松树下的地块施用pH 3的酸雨会导致越桔的覆盖度增加，而仅施用硝酸时，黑果岩高兰的新梢数量会有短期增加。与营养生长相反，矮灌木的繁殖受酸雨影响更大，但这也取决于当地条件和酸雨的阴离子组成。在“松树”地块上，pH 3的雨水减少了黑果岩高兰顶生当年生枝条上的浆果和花芽数量，然而，这在分株水平上浆果产量的增加中得到了部分补偿。模拟酸雨对越桔的浆果产量主要有负面影响。
