青藏高原东部原始云杉林及其系列采伐迹地3个林地藓类种群结构与生物量的差异性评估(英文)

Evaluating the Changes in Structure and Biomass of Three Common Forest-floor Mosses in Cutovers and Primary Spruce Forest in the Eastern Tibetan Plateau

森林采伐对地表藓类种群的发育具有重要影响,但很少有人评估这种影响后迹地上的藓类种群状况.本研究调查了四川壤塘县4个系列采伐迹地和附近原始云杉林下3种林地优势藓类种群[锦丝藓(Actinothuidium hookeri)、塔藓(Hylocomium splendens)和大羽藓(Thuidium cymbifolium)]的发生频率和盖度、生物量以及维管束植物盖度和凋落物盖度,通过方差分析检验比较分析了3个藓类种群的盖度和生物量在不同采伐迹地及原始林之间的差异,评估了其自然发展趋势,揭示了维管束植物结构参数与藓类种群盖度和生物量之间的相互关系.发现:1)3种藓类种群的盖度和生物量在采伐迹地和附近原始林间有显著差异,但在系列采伐迹地之间没有明显差异,证实森林采伐后林生地表藓类种群显著衰退,随着迹地自然恢复进程这些藓类种群并未能逐渐恢复;2)微环境尺度上的藓类盖度和生物量在系列采伐迹地之间有较大的波动,Spearman相关分析显示乔木和草本层盖度是影响藓类种群生物量的主要因子.综合分析表明,采伐导致的环境变化以及藓类自身的生态适应性和繁殖策略综合决定着藓类种群的自然恢复能力;如果仅仅依靠迹地自然恢复过程,顶极藓类种群(塔藓和锦丝藓)是难以自然复壮的.

Forest felling is known to seriously affect forest-floor bryophyte population development, but few studies have done to investigate the temporal change of bryophyte population along the cutover restoration process. Selecting three preponderant forest-floor mosses distributing extensively in primary coniferous forests in the eastern Tibetan Plateau, Actinothuidiurn hookeri, Hylocomium splendens and Thuidium cymbifolium, we investigated their frequency, cover and biomass, as well as vascular plant cover （including herbs and shrubs） and litter, in four cutovers with similar background but with different felling time and a nearby primary spruce forest in Ramtang, Sichuan and compared their differences in population structure and biomass. We aimed to assess their changes in structure and biomass of the three moss populations following forest felling. In particular, we tried to test two hypotheses： 1） Forest-floor moss populations would decline significantly after forest felling due to environmental alteration; and 2） they would be gradually restored during the early natural restoration process of cutover vegetation. We found： 1） the three mosses all showed significant differences in cover and biomass between the cutovers and the primary spruce forest, confirming the first hypothesis; however, 2） all the three populations did not show apparent differences in population structure and biomass along the cutover restoration chronosequence, disagreeing with the second hypothesis. The large variability in cover and biomass in the cutovers, on a microhabitat scale, indicated that these three populations were more dynamic in the cutovers than in the primary spruce forest. Spearman rank correlation analysis revealed that both tree and herb covers were crucial factors impacting forest floor bryophyte population biomass. Our results suggested that the features of the three moss populations in the cutovers were indicative of their ecological adaptations and reproductive strategies and of the environmental alteration created by clear-felling, and it was difficult for recovery and restoration of two climax populations, A. hookeri and H. splendens, if only relying on natural restoration in the alpine cutovers in the eastern Tibetan Plateau. Fig 6, Tab 4, Ref44