冀西北坝上地区围封对植物物种多样性及生物量的影响

Impact of enclosure on plant diversity and biomass in the Bashang area in northwest of Hebei Province

冀西北坝上地区为典型的生态脆弱区,为了解围封对冀西北坝上地区植被的影响,对封育林地及未封育林地草本植物层的物种多样性及其生物量进行调查研究。结果表明:围封采伐地内草本植物的科、属、种数量,以及α多样性指数均显著高于未围封林地(P<0.05);围封林地内草本植物的丰富度指数高于未围封林地(P<0.05),但多样性指数和均匀度指数低于未围封林地(P<0.05)。3种林地的生物量具有显著差异(P<0.05),以围封采伐地最高,围封林地次之,未围封林地最低,未围封林地仅为围封林地、围封采伐地的49%和23%。该地区草本植物层中具有典型草原的建群种,包括冰草(Agropyron cristatum)、羊草(Leymus chinensis)和针茅(Stipa capillata)等,且已成为该地区的优势种。由此得出结论,围封明显提高了冀西北坝上地区草本植被的物种多样性及生物量,促进了草本植被的恢复;通过围封排除外来干扰可促进该地区草本植被向地带性草原植被的演替。

The Bashang region is an ecologically fragile area in northwest of Hebei Province.In order to understand the impact of enclosure on the vegetation in the region,a field survey was carried out to measure the species diversity and biomass of herb layers in enclosed woodlands and unenclosed woodlands.The results showed that the number of families,genera,and species of the herbs in the enclosed newly harvested forest land(ENFL)and theirαbiodiversity index were significantly higher than that in the unenclosed forest land(NEFL)(P<0.05).The enclosed forest land(EFL)was higher than NEFL in herb richness(P<0.05),but lower in biodiversity index and evenness index(P<0.05).There was a significant difference among different forest lands in herb biomass(P<0.05).ENFL were the highest in biomass,followed by EFL,and NEFL were the lowest,which were only 49%and 23%of the EFL and ENFL.In the herb layer of this area,some species dominated in the typical steppe,such as Agropyron cristatum,Leymus chinensis and Stipa capillata were found,and they had become the dominant species in the herb layer in the area.It was concluded that the enclosure significantly increased the species diversity and biomass of the herb vegetation in the Bashang area of northwestern Hebei,and promoted the restoration of the herb vegetation.The exclusion of external disturbances through the enclosure can promote the succession of the herb vegetation to the zonal steppe.