【摘要】 连续2年对不同退化程度天然干旱荒漠草原围封后群落的土壤种子库进行研究。结果显示,土壤种子库物种数、种子密度和植物生活型在年际间、封育与放牧样地间及退化梯度间均有明显差异。种子库物种数为封育高于放牧样地;退化梯度相比,物种数除2003年封育样地随退化程度加剧呈减少趋势外,放牧样地及2004年各样地均随退化程度加剧而增加。种子库密度结果显示,2003年种子库密度明显高于2004年;各封育样地2年中土壤种子库密度显著或极显著(P<0.01)高于放牧样地;退化梯度相比种子库密度除2003年封育样地随退化程度加剧而急剧增加外,其余各样地种均随退化程度加剧而明显下降。植被生活型分析结果为,2003年以一年生草本植物种出现频率最高,各样地分别达94.0%~98.4%,多年生草本及灌木出现频率则很低,分别为1.59%~5.15%和0.03%~0.4%,2004年则为多年生草本植物种比例上升,且显示出封育高于放牧、退化程度愈轻增幅愈大的趋势。2年的结果显示种子库物种Shannon-W iener多样性指数和Pe ilow均匀性系数均以封育低于放牧样地。种子库密度与地上植被盖度相关性分析表明,2年结果中仅一年生草本和2003年灌木的土壤种子库密度与相应地上植被盖度之间具相关趋势和显著(P<0.01)相关。更多还原

【Abstract】 The soil seed banks of the communities in differently degenerated grasslands in which grazing was suspended by fencing were studied in consecutive two years.The results showed that the soil seed banks appeared significantly different in species number,seed density and life form between the different years,the quadrats under grazing and grazing suspension and the different degeneration gradients.The soil seed banks showed a higher species number in the grazing-suspended grassland than in the grazing grassland;the species numbers in the grazing-suspended quadrats of 2003 tended to decrease as the degeneration gradient increased but these in the grazing quadrats of 2003 and the various quadrats of 2004 increased as the degeneration gradients increased.The seed densities in the study showed that the seed densities of the soil seed banks in 2003 were remarkably higher that those in 2004;in the two years,the seed densities of the soil seed banks in the grazing suspended quadrats were remarkably or significantly(p<0.01) higher than those in the grazing quadrats.The seed densities in all the quadrats of 2003 but the grazing suspended ones whose seed densities remarkably increased as the degeneration gradients increased decreased remarkably as the degeneration gradients increased.The analysis of the life forms indicated that in 2003,annual herbaceous plants had the highest occurrence frequency which stood at 94.0%～98.4% in the various quadrats,and perennial herbaceous plants and shrub plants had low occurrence frequencies which were 1.59%～5.15% and 0.03%～0.4%,respectively.In 2004,perennial herbaceous plants showed an increased proportion and the proportion appeared higher under grazing-suspension than grazing and tended to have a high increment as the degeneration gradients decreased.The results of the two-year study indicated that the Shannon-Wiener’s diversity indexes and Peilow evenness indexes of the soil seed banks were lower in the grazing-suspended quadrats than in the grazing quadrats.The correlation analysis of the seed densities and vegetation coverages in the two consecutive years illustrated that the annual herbaceous in only one year of the two years and the shrub plants in 2003 had the seed densities which tended to correlate or significantly correlate(P<0.01)with the corresponding vegetation coverages.更多还原