| Most of the analyses on vegetation of Yellow River Delta concentrated on the vegetation type, based on the reaserch and the survey samples, we analysed the correlation between vegetation and soil, take the corridor effect of Yellow River as the clue, we analysed the characters of vegetation and the status of biodiversity, and reaserched the correlation with drought arid/semi-arid region; Most of the research on no-flow of Yellow River with climate based on large river basin and long peroid, the conclusion usually was indefinite. For the situation, we used the data of annual average precipitation and air temperature of 25 weather stations (1972-2000) up Inner Mongolian along Yellow River, analysed the correlation with annual average runoff of Lijin station, Dongying. Based on the multi-temporal Remote Sensing data , the statistical data of Dongying city and the survey on the ground, we completely analysed the status of land use/cover and its dynamic change.The main conclusions are as follows:1. The landscape type of land use/cover and the statusThe landscape type of land use/cover in Yellow River Delta include foreshore, billabong, flat, fluvial elevation, hillock and river bottomland. The total area is 7650.37 km2, farmland is the largest type. The un-used land types such as Foreshore, Suaeda bare land, Tamarix chinensis boskage and Phragmites austral is meadow occupies a great deal of proportion.2. The dynamic of land use/coverFrom 1978 to 1987 and 2002, the filling up exceeded eroding, so that the area of Yellow River was increased. In the three years, the largest land use/cover type was farmland. During the whole period, the change of farmland, rural resident and Water course was little, but the other types changed frequentlly from one to another, which showed the constant evolvement character of Yellow River Delta as a young land ecosystem predominately with saline soil.In each stage, the spacial evolvement for each land use/cover type was different too. From 1978, the largest spacial evolvement took place among the un-used land use/cover types.3. The landscape pattern character of land use/cover and the dynamic changeFarmland was the predominate landscape type, foreshore, Stiaeda bare land or Phragmites australis- Tamarix chinensis was the second one. Wholly, the un-used land type occupied a great deal of proportion, so the land use potential was great. The patch number of rural resident, artificial reservoir and Stiaeda bare land was great, which showed that the fragment degree was increased.Under the human disturbance, the landscape pattern of Yellow River Delta changed obviously. From 1978, the general shape index increased, which showed that: with time went on, the patch shape became complicated and the fragment degree increased. Although the dominance index decreased, but the dominance index was still larger, which showed that there were obvious dominant landscape types in the Delta. The whole evenness index increased too.4. The character of ecosystem and biodiversityThe average salt content, organic material content, the N and P content among 0-30cm soil layers changed regularly under different vegetation.The previous research gave emphases on the survey and analysis of vegetation, we analysed the bildiversity correlation between Yellow River Delta and the border region. The characteristics of biodiversity of Yellow river delta are as follows: the flora composition is simple, the community structure was simplex, the vegetation coverage was lower, the plants usually could resist against salt and drought; It charactered with obvious younger nature; Wetland is flourishing; the xerophytes and meso-xerophytes are abundant, there are many mutual species with Inner Mongolia, which incarnated the biology corridor function of Yellow River; There are many species belong to national protected species, so that the significance for biodiversity protection is great.5. The no-folw in the lower Yellow River and its ecological affectionYellow River dried out naturally first time in 1972, from then on, it had happened in 20 years by the end of 2000. The phenomena of no-flow showed a tendency that the beginning time advanced greatly, the interval of dry out prolonged and the river segment drought out gradually extended to the upriver.Using the data of annual average precipitation and temperature of 25 weather stations along Yellow River, we first made the quantitative correlation analysis on the precipitation and temperature with annual average runoff of Lijin of Dongying city. The runoff of lower Yellow River correlated closely with the 80% weather stations along Yellow River in Qinghai and upwardsDongxiang of Gansu(correlation coefficient exceed 0. 3, reliability degree exceed 90%), but had no correlation with the precipitation of the weather stations downwards Dongxiang, even had negative correlation; The air temperature of most stations(except Gande station in Qinghai: correlation coefficient is 0. 06, reliability degree is 22%) had obvious negative correlation with the runoff of lower reaches(correlation coefficient exceed -0. 356, reliability degree exceed 94. 2%).Influenced by the no-flow of Yellow River in 1997; the land use/cover changed obviously Within 10 km intercostals buffer region along the river in Yellow River Delta, from 1987 to 1997, a great deal of un-used land changed into farmland, but from 1997 to 2002, a lot of farmland changed into other land types.Yellow River schlepped a great deal of sand into the sea, it caused the coastline of Yellow River Delta filled up to sea. But affected by the no-flow and the decreased flux of Yellow River, the filling up speed decreased constantly, a part of coastline had transformed from filling up into eroding.
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