高寒干旱草原披针叶黄华植物群落土壤种子库与地上植被的关系

摘要

以祁连山高寒干旱退化草地披针叶黄华(Thermopsis lanceolate)群落为研究对象,采取野外调查取样和室内分析相结合的方法,对群落土壤种子库与地上植被的关系进行了对比研究.结果表明:地上植被物种共调查出15种,土壤种子库检测出植物18种,地上植被阿尔泰针茅(S.krylovii)、赖草(A.dasystachys)和扁穗冰草等可食草以及不食草披针叶黄华和阿尔泰狗哇花(H.altaicus)优势度明显,其它物种不明显;土壤种子库与地上植被物种组成的相似性程度较低;土壤种子库与地上植被中可食草的物种数多于不食草,土壤种子库的物种数均不小于地上植被中的物种数,地上植被中存在而未在土壤种子库中检测到的可食草物种有阿尔泰针茅和赖草,土壤种子库中存在而地上植被中未被发现的物种有早熟禾(P.annua)、灰绿藜(C.glaucum)、碱韭(A.polyrhizum)、酸模(R.patientia)、独行菜(Lapetalum和秦艽(G.macrophyUa);原生禾草物种在可食草功能群中生物量所占比例较低,毒杂草物种生物量所占比例增加显著,而土壤种子库的数量百分含量较低;可食草与不食草的生物量在植被梯度下的变化呈显著负相关(r=-0.940,P=0.018),而土壤种子库密度变化无相关性;可食草生物量变化与其土壤种子库密度变化不相关,不食草生物量变化与其土壤种子库密度的增加呈显著正相关(r=0.902,P=0.036).%The main objective of this study was to address questions with regard to how the soil seed banks and vegetation change along a habitat gradient.In this article,we chose the Thermopsis lanceolata community in degraded alpine arid grasslands as our research subject and determined the relationship between the alpine arid grassland soil seed bank and above-ground vegetation in the Qilian Mountains using field investigation and laboratory analysis.Fifteen species were present in the above-ground vegetation and 18 species were present in the soil seed bank.Dominant above-ground vegetation species included edible grasses such as Stipa krylovii,Aneurolepidium dasystachys and Agropyron cristatum,and non-edible grasses such as Thermopsis Lanceolata and Heteropappus altaicus;however,no other species was observed to exhibit any distinct dominance.Moreover,the degree of similarity between the above-ground vegetation and the soil seed bank was distinctive.The Sorenson similarity index was low between the above-ground vegetation and the soil seed bank along the vegetation gradient.The Sorenson similarity index between the soil seed bank and observed vegetation functional groups exhibited varying characteristics.The number of edible grasses was greater than that of non-edible grasses in the soil seed bank (except V gradient).The number of species of vegetation was also greater than that of non-edible grasses (except III gradient).The number of species in the soil seed bank was not lower than that of the above-ground vegetation species.S.krylovii and A.dasystachys were founded in the above-ground vegetation but not in the soil seed bank,whereas Poa annua,Chenopodium glaucum,Allium polyrhizum,Rumex patientia,Lepidium apetalum,and Gentiana macrophylla were found in the soil seed bank but not in the vegetation.The proportion of biomass attributable to gramineous plants was low for edible grasses,whereas the biomass of poisonous weeds was significantly greater in the vegetation gradient than in the soil seed bank.The plant population biomass had no unanimous relation with seed amount.Edible grass and non-edible grass were significantly negatively correlated (r=-0.940,P=0.018) along the vegetation gradient,but changes in the soil seed bank density were not correlated.The relationship between the biomass of edible grass and the soil seed bank density was uncorrelated.The biomass of non-edible grass and the soil seed bank density were significantly correlated along the vegetation gradient (r =0.902,P =0.036).Our research indicated that the seed bank could retain and restore several species in the process of grassland degradation,and these species could be valuable for vegetation succession and grassland restoration.