ANgIllACT: There are 463 species of woody plant, belonging to 166 genera and 70 families in Shanxi, North China. The floristic composition types of genera and species are abundant, in which the compositions distributed in temperate zones (including North Temperate, Old World Temperate and Temperate Asia), having 62 genera, are dominant and account for 38.27% in total genera (except for Cosmopolitan), and they are major constructive or dominant species of vegetation in Shanxi. The floristie compositions of woody plants of Shanxi, Hebei, Beijing, Shandong, Henan, Jiangxi and Inner Mongolia were studied comparatively by using diversity index, principal component analysis (PIEA) and group-average clustering, respectively. The florisfic composition of Shanxi was considerably similar to that of Hebei, Beijing and Shandong because they shared a lot of genera, specially genera distributed in temperate regions, such as Rosa, Quercus , Populus , Salix , Acer , Ulrnus , Pinus etc. and their eco-environment were considerably similar. However, the flora of Sha~i was comparatively different from that of Henan, ]iangxi and Inner Mongolia by reason that there were distinct differences among their coo-geographic conditions, floristie compositions and constructive or dominant species of dominant vegetation types.

Forest soil is a major component of terrestrial ecosystems for carbon sequestration and plays an important role in the global carbon cycle. Soil carbon flux and soil carbon pools were investigated in a poplar plantation chronosequence over a rotation in northwest China. Based on continuous field observation in 2007, the results showed that mean soil CO 2 efflux rate was 5.54, 4.81, and 3.93 lmol CO 2 m À2 s À1 for stands of 2-, 8-, and 15-year-old, respectively, during the growing season. Significant differences in soil respiration of three age classes were mainly because soil temperature, carbon allocation, and fine root growth changed greatly with stand age. Multiple regression analysis suggested that soil temperature and fine root biomass in the upper layer could explain 78-85% of the variation in soil respiration. Mineral soil C stock at 0-40 cm depth was 55.77, 55.09, and 58.14 t ha À1 in the 2-, 8-, and 15-year-old stands, respectively. The average rate of soil C sequestration was 0.13 t ha À1 year À1 following afforestation on former crop lands. Although the plantations had similar management practices and soil types since their establishment, many biotic and abiotic factors such as root biomass and turnover rate, soil condition of the plantations had undergone marked changes at different development stages, which could result in the remarkable differences in soil carbon flux and storage over a rotation. Our results highlight the importance of the development stage within a rotation of poplar plantation in assessment of soil carbon budget.

The exploitation and utilization of coal resources have been lasting for thousands of years, resulting in a series of ecological environmental problems in China. So far, the mining area has changed into severe and typical damaged ecosystem locally and globally. The coal exploitation history is long in Shanxi province, but goafs are distributed widely. In this study, we addressed this point and took a coal mine, located in Shanxi province where the coal mining has a long exploitation history with goaf densely distributed, as an example. The growth patterns of above ground plant communities, succession characteristics of vegetation community and soil quality characters in the goafs, which could provide theoretical basis for the sustainable development of coal resources and ecological reconstruction in this region, have been studied.

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The influence of soil physicochemical properties and the relationship between the plant community and edaphic factors have been studied through monitoring the community dynamic parameters and analyzing the soil properties from four plant plots at the Pingshuo opencast coal mine eco-reclamation area. The results are obtained as follows:(1) the law of the quantity variation of total N and available K is affected by the different kinds of plant configuration mode. It is Robinia pseudoacacia þ Pinus tabuliformis (SIV) > R. pseudoacacia (SV) > R. pseudoacacia þ P. tabuliformis (SI) > R. pseudoacacia þ Ulmus pumila þ Ailanthus altissima (SIII). The quantity is close to or exceeds the level of the original geomorphology. The average content of available N has the following order: SIV > SI > SIII > SV; the average content of available P SV > SIII > SIV > SI, both are far below the level of the original geomorphology; pH SIV < SIII < SI < SV; bulk density SI < SIV < SV < SIII, moisture content SIV > SIII > SI > SV; in the soil layer of 20-40 cm, except the available P, other physicochemical factors are in accordance with the factors of the surface soil; (2) the population average density, height and diameter at breast height (DBH) have no obvious relevance with the average density of the stumpage; (3) the average density, height, and DBH of R. pseudoacacia are closely related to pH and the content of available N and available P and all the index can be fitted by the equation of linear regression of the edaphic factors mentioned above. The principal component analysis shows that the magnitude of the impacts of three kinds of edaphic factors on the R. pseudoacacia population has the following order: pH > available N > available P. The average density of U. pumila is closely related to the moisture content of the soil. This regression model can be used to direct the cultivation and propagation of R. pseudoacacia and U. pumila population at the mine eco-reclamation area.