| Soil seed bank is an important research area in plant ecology. The soil seed bank is potential community, which is the important material base on natural vegetation update. Soil seed bank has important theoretical value and practical significance in ecological systems of restoration. The Huangfuchuan watershed warm-grassland has great representation in the Mongolian Plateau grassland. Huangfuchuan in transition zone between warm temperate and mid temperate, belonged semi-arid grassland. It is in ordos plateau and the loess plateau, domidated by hills and donga ravine. Because of reclamation and heavy grazing, natural vegetation was destroyed. It is important in theoretical value and practical significance to reveal the characteristics of the seed bank in degradated grassland restoration process. It has great value to configurate species and species group vegetation in restoration work. So, we were conducting experiments in soil and water conservation in Huangfuchuan. Thymus serphyllum + Cleistogenes squarrosa community sample I was chosen because of degradation in east coast of the second tributary of Huangfuchuan watershed. Other three samples were chosen in Hejiawan which is in the east coast of the second tributary of the Huangfuchuan watershed warm-grassland. Cleistogenes squarrosa+Leymus chinensis community sample II had been recovered 20 years, Leymus chinensis+Poa sphondylodes community sample III had been recovered 25 yeas and recovered 30 years Stipa bungeana community sample IV. In order to reveal the characteristics of successional stages of soil seed banks and dynamics of soil seed bank, soil samples were collected in early April, late June, late August 2007 and Early April, late June, late August 2008. Soil seed banks composition and structure were identified using germination method. The method of taking samples was line-intercept method and in large quantity. Our results are described as follows:1. Seasonal dynamic of the soil seed bank in each sample in same year.Species, density and Shannon-Wiener index of soil seed bank of each samplewere maximum in August 2007 and August 2008, minimum in June. Proprotion of perennial herb soil seed bank was highest in June 2007 and June 2008. Xerophil soil seed bank was highest in June 2007 and June 2008. Similarity of soil seed bank of sample I and sample IV between April and August 2008 was highest, lowest between June and August. Similarity of soil seed bank of sample II and sample III between April and June 2008 was highest, lowest between June and August. Similarity of soil seed bank was lowest between June and August.2. Comparision of characteristics of the soil seed bank between in 2007 and 2008. Similarity of soil seed bank of each sample between April 2007 and April 2008 was above average, low in June 2007 and June 2008, low in August 2007 and August 2008. So, persistent soil seed bank is stable than temporary soil seed bank.3. Characteristics of the soil seed bank of each sample at same time.After investigation two years display: with the succession species and density of soil seed bank increased in April, June and August 2007 and April, June and August 2008, density of perennial herb soil seed bank and density of xerophyte soil seed bank were also.ANOVA analysis suggested density of soil seed bank of four samples in 2007 had significant difference(F=47.890, P<0.001, df.=41). ANOVA analysis suggested density of soil seed bank of four samples in 2008 had significant difference(F=9.885, P<0.001, df.=71). So, density of soil seed bank of managed samples had significant difference with non-managed sample, and managed samples had significant difference with each other.4. Relation between Characteristics of the soil seed bank in 2007 and 2008 and standing vegetation of samples.Similarity between soil seed bank of sample IV in August 2007 and it's standing vegetation was highest. Similarity between soil seed bank of sample II in June 2008 and it's standing vegetation was highest. It demostraed that similarity between soil seed bank and standing vegetation emerged in restored long sample.Regardless of 2007 or 2008, similarity between soil seed bank and it's standing vegetation was highest in samples.In April, June 2007 and April, June and August 2008, similarity between soil seed bank of same sample was higher than similarity between soil seed bank and it's standing vegetation. It demostraed that seed bank was more stable than standing vegetation. Similarity between soil seed bank of same sample in August 2007 was lower than similarity between soil seed bank and standing vegetation. Because of latly sampling, seeds just fell and didn't germinate, so similarity between soil seed bank and standing vegetation was higher than similarity between soil seed bank of same sample.
|
PDF Full Text Request