【作者】 张黎敏；

【导师】 龙瑞军；

【作者基本信息】 甘肃农业大学 ， 草业科学， 2005， 硕士

【摘要】 对江河源区“黑土型”退化高寒草地(近似未退化草地,轻度退化草地,中度退化草地和重度退化草地)的土壤种子库数量特征、地上植物群落特征、土壤理化性质和植物种子大小等进行系统研究。结果如下: 1、不同退化程度高寒草地种子库存量间差异不显著(P﹥0.05),轻度退化草地种子库存量最大( 15466.67±6072.02 粒/ ㎡), 重度退化草地种子库存量最小(9422.22±1904.09 粒/㎡);不同样地土壤种子库可萌发种子数量是近似未退化草地最少(2374.40±830.28 粒/㎡);轻度退化(7712.00±1395.81 粒/㎡)、中度退化(8614.40±3431.11粒/㎡)和重度退化(6899.20±1514.03 粒/㎡)草地土壤种子库可萌发种子数量间差异不显著(P﹥0.05)。2、近似未退化高寒草地可萌发种子粒径主要介于0.5 ㎜~2 ㎜之间;其余3 种退化草地可萌发种子粒径则介于0.25 ㎜~0.5 ㎜之间。退化高寒草地土壤种子库中可萌发种子总量的94%~98%集中于0.25 ㎜~2 ㎜粒径范围之内。粒径大于6 ㎜的可萌发种子数占可萌发种子总数的2%~6%,小于0.25 ㎜粒径土样中未发现可萌发种子。3、四个样地种子库萌发的种子数量时间格局都近似单峰型,单子叶植物在10 天左右开始萌发,双子叶植物种子5~7 天内开始萌发。中度退化和重度退化样地单子叶植物种子萌发较少,因此这两个样地种子萌发动态基本表现为双子叶植物种子的萌发动态。4、在不同退化阶段各样地植物种类组成发生着一定的变化。从近似未退化草地至重度退化草地,地上植被种类组成成分逐渐从以优良牧草为优势植物演替为以菊科植物和毒杂草为优势;随退化程度的加剧土壤容重呈上升趋势,土壤养分和水分大体呈下降趋势。5、对在试验区域采集的51 种地上植被种子称重发现,种子重量在0.0~25.0mg 的植物种子有40 种,占所实验种子的78.43%,且以多年生植物种子为主(82.35﹪)。更多还原

【Abstract】 The study on quantity characteristics of soil seed bank, standing vegetation, soil physical and chemical property, seed size and weight and so on were carried out in the 4-types of alpine meadows i.e. non-degraded meadow; minor degraded meadow; medium degraded meadow and heavily degraded meadow. The results as follows: 1. The difference of soil seed bank storage was not notable among different 4-types of meadows. The most was minor degraded meadow (15466.67±6072.02 seed/㎡) and the least was heavily degraded meadow (9422.22±1904.09seed/ ㎡). The amount of germinative seeds of soil seed bank in non-degraded meadow (2374.40±830.28 seed/㎡)was less than the other degraded meadows. Whereas no significant different (P﹥0.05) was shown among the minor degraed meadow (7712.00±1395.81seed/㎡), the medium degraded meadow (8614.40±3431.11seed/ ㎡) and heavily degraded meadow (6899.20±1514.03seed/㎡). 2. The soil samples from each type of alpine meadows were separated through 4 kinds of sieves with mesh size of 0.25 ㎜, 0.5 ㎜, 2.0 ㎜and 6.0 ㎜. The results showed that the diameter of the germinative seeds from non-degraded meadow mainly dropped to the size ranged from 0.5 ㎜to 2 ㎜while the diameters of the germinative seeds in the soil samples from the rest 3 types of degraded meadows concentrated on the range of 0.25 ㎜~0.5 ㎜. The further statistical data indicated that 94%~98% alpine meadows germinative seeds have a diameter range of 0.25 ㎜to 2㎜. Only 2%~6% germinative seeds were found in the soil samples of over 6㎜.There was no germinative seeds existed in soil samples of less than 0.25 ㎜. 3. The number and time situation of germinative seeds from each type of alpine meadows are both close to unimodal curve. The monocotyledon seeds began to germinate after ten days and the dicotyledon seeds began to germinate after five or seven days. The monocotyledon germinative seeds of medium and heavily degraded meadow were less than non-degraded and minor degraded meadow. Consequently the germination dynamic of the couple of samples both manifest the germination dynamic of dicotyledon seeds. 4. The plant community composition of different degraded meadows was changed. Species composition of standing vegetation took place change with the increasing of degradation. From non-degraded meadow to heavily degraded, the composing element of vegetation changed from good grasses to noxious weed gradually. The soil nutrients, soil moisture decreased and soil bulk density increased with gradually degrading. 5. The seed size and weight of 51 plant species in test area was researched. There were seeds weight of 40 species concentrated on the range of less 25.0mg, was 78.43% of all testing seeds. Moreover the most were perennial plant seeds (82.35%).更多还原