沙尘沉降可能阻滞泥炭地植被的自发演替

以长白山区泥炭地的6种泥炭藓孢子和8种维管植物种子为受试材料,进行室内模拟实验,对比研究了沙尘沉降对泥炭藓孢子和维管植物种子萌发的影响。数据分析显示,施加沙尘抑制除锈色泥炭藓外其他所有泥炭藓孢子的萌发,在接近自然沉降的50 g/(m²·a)水平时,这些泥炭藓孢子的萌发率均下降一半以上。无论沙尘施加量如何,有4种维管植物种子均未萌发。施加沙尘抑制了狭叶杜香（Rhododendron tomentosum）和小白花地榆（Sanguisorba parviflora）种子的萌发,但却对宽叶杜香（Rhododendron palustre）和燕子花（Iris laevigata）种子的萌发呈现一定的促进趋势。研究表明,沙尘沉降可抑制泥炭地泥炭藓孢子和部分典型维管植物种子的萌发,但可能会对非典型的或喜营养的泥炭地维管植物种子萌发产生促进作用。所以,长期存在的沙尘沉降,可能通过提高泥炭地N、Ca水平和pH值的作用,抑制泥炭藓孢子定居,阻滞中国长白山区泥炭地自发演替的进程。

Sand and Dust Deposition May Retard the Autogenic Vegetation Succession of Peatlands

Peatlands usually are acid, nutrient-poor and mineral deficient. The effect of sand and dust with nutrients, mineral elements and high pH on plant population regeneration and vegetation succession in peatlands is unknown. The spores of six Sphagnum species and the seeds of eight vascular plants from the peatlands of the Changbai Mountains were chosen as experimental materials. We carried out an indoor simulation experiment to comparatively study the effect of sand and dust deposition on bryophyte spores and vascular plant seeds. Sand and dust addition inhibited spore germination in Sphagnum. At the level of 50 g/(m²·a) close to natural deposition in Hani Peatland, spore germination percentage decreased more than 50% compared with that without sand and dust addition in the bryophytes except S. fuscum. No matter how much sand and dust were added, the seeds of four vascular plants did not germinate. It decreased germination percentage of the seeds of Rhododendron tomentosum and Sanguisorba parviflora but tended to facilitate seed germination in Rhododendron palustre var. dilatatum and Iris laevigata. Our study suggests that sand and dust deposition may inhibit the germination of Sphagnum spores and some typical peatland vascular plants but may be in favor of the seed germination of non-typical or minerotrophic peatland vascular plants. We hence put forward the hypothesis that by increasing the concentration of N and Ca and pH, long-lasting sand and dust deposition probably has inhibited Sphagnum spore establishment to retard the autogenic succession of peatlands in the Changbai Mountains.