To further understand the relationship between vegetation succession and soil fertility within farming-plantation ecotone in Ziwuling Mountains of the Loess Plateau, nine kinds of widely distributed communities at dif...To further understand the relationship between vegetation succession and soil fertility within farming-plantation ecotone in Ziwuling Mountains of the Loess Plateau, nine kinds of widely distributed communities at different succession stages were selected, and the effects of vegetation succession on soil fertility were studied through the methods of comparing two hierarchical clustering （similarity index： B） and other multivariate analysis. The results showed that： （i） the similarity in clustering pattern of nine communities which classified by plant species and soil nutrients respectively showed a trend of B ^-overall plant-soil0-10cn〉B^-overall plant-soil 10-20 cm 〉B^- overall plant-soil 20-40 cm, and for the top soil, it showed a trend of B^- grass-soil 0-10 cm 〉 B^-shrub-soil 0-10 cm 〉 Btree-soil0-10 cm; （ii） soil fertility increased during the succession process from abandoned land to forest community, and the soil fertility of forest community showed an increased order of coniferous forest →mixed forest →broadleaf forest; （iii） during the process of vegetation succession, the variation of topsoil fertility was higher than that of the subsurface soil （coefficient of variation： CV0-10 cm 〉CV 10-20 cm 〉 CV20-40 cm）, and when the succession developed into the stages of shrub and forest communities, the top soil fertility had been improved significantly; and （iv） for the subsurface soil of the communities at the advanced succession stages, the soil fertility also increased to some extent. Our results suggested that the method of comparing two hierarchical clustering reflected the similarity level of different cluster patterns, therefore, it was helpful to study the relationship between vegetation succession and soil fertility. There was a corresponding relationship between the change process of soil fertility from the top soil to subsurface soil and the process of vegetation succession from the early stages to the advanced stage. The differentiations of soil fertility in vertical space and horizontal space were both caused by vegetation succession, which was significant for both the shrub and forest communities. The improved level of forest soil fertility was related to forest vegetation types and the improved fertility level of broad-leaved forest-soil community was higher than that of the coniferous forest soil. In the practice on soil fertility ecological restoration of the loess plateau, it is important to carry out reasonably artificial forestation so as to enhance the restoration and improvement of soil fertility.展开更多
Information from eleven profiles of eolian earthy red silty clay and loess of the middle of the Late Miocene to Holocene age have been studied and correlated.A complete summary profile with projected isotopic ages and...Information from eleven profiles of eolian earthy red silty clay and loess of the middle of the Late Miocene to Holocene age have been studied and correlated.A complete summary profile with projected isotopic ages and fossil-bearing beds has been assembled.The profile is subdivided into 12 stratigraphic units proceeding from the lower(older)to the upper(younger)one.The character of mammalian assemblages contained in each unit was analyzed and the corresponding pa-leo-climatic environments were deduced.The environmental character of each period and the change from the middle of the Late Miocene at about 8.0 Ma B.P.up to the Holocene progressed from the hot semiarid and semi-moist,warmer-moist,warm-moister of the Late Miocene.To slightly less warm moist,cool-dry,slight-warmer-moister of the Pliocene;later the cool to cold dry periods alternated frequently with the mild semiarid and semi-moist periods of the Quaternary.Vegetation progressed from the grasslands with sparse woods,wooded shrub-grasslands and subtropical forest-grasslands of the Late Miocene age to sparse grasslands and dry grasslands of the Pliocene;and to sparse grasslands,dry grasslands and tundras of the Quaternary.The climate changes in the Neogene were of low-amplitute in a generally warm-humid background.Those of the Quaternary were of higher am-plitude with a longer phase.Cool or cold dry and slightly warm semiarid and semi-moist climates al-ternated on a generally cool-dry background.The tendency since the start of the Quaternary was the change to more northern and western shift in the Loess Plateau,with progressively cooler and dryer conditions.The dramatic uplift of the Qinghai-Xizang(Tibet)Plateau and the forming and expansion of the Arctic ice sheet might be the main reasons of the more pronounced changes in the Quaternary.展开更多
基金supported by the National Key Basic Research Program of China(973Program,2002CB111505)
文摘To further understand the relationship between vegetation succession and soil fertility within farming-plantation ecotone in Ziwuling Mountains of the Loess Plateau, nine kinds of widely distributed communities at different succession stages were selected, and the effects of vegetation succession on soil fertility were studied through the methods of comparing two hierarchical clustering （similarity index： B） and other multivariate analysis. The results showed that： （i） the similarity in clustering pattern of nine communities which classified by plant species and soil nutrients respectively showed a trend of B ^-overall plant-soil0-10cn〉B^-overall plant-soil 10-20 cm 〉B^- overall plant-soil 20-40 cm, and for the top soil, it showed a trend of B^- grass-soil 0-10 cm 〉 B^-shrub-soil 0-10 cm 〉 Btree-soil0-10 cm; （ii） soil fertility increased during the succession process from abandoned land to forest community, and the soil fertility of forest community showed an increased order of coniferous forest →mixed forest →broadleaf forest; （iii） during the process of vegetation succession, the variation of topsoil fertility was higher than that of the subsurface soil （coefficient of variation： CV0-10 cm 〉CV 10-20 cm 〉 CV20-40 cm）, and when the succession developed into the stages of shrub and forest communities, the top soil fertility had been improved significantly; and （iv） for the subsurface soil of the communities at the advanced succession stages, the soil fertility also increased to some extent. Our results suggested that the method of comparing two hierarchical clustering reflected the similarity level of different cluster patterns, therefore, it was helpful to study the relationship between vegetation succession and soil fertility. There was a corresponding relationship between the change process of soil fertility from the top soil to subsurface soil and the process of vegetation succession from the early stages to the advanced stage. The differentiations of soil fertility in vertical space and horizontal space were both caused by vegetation succession, which was significant for both the shrub and forest communities. The improved level of forest soil fertility was related to forest vegetation types and the improved fertility level of broad-leaved forest-soil community was higher than that of the coniferous forest soil. In the practice on soil fertility ecological restoration of the loess plateau, it is important to carry out reasonably artificial forestation so as to enhance the restoration and improvement of soil fertility.
基金supported by the State Key Laboratory of Loess and Quatemary Ge-ology,CAS(Grant No.SKLLQGO219).
文摘Information from eleven profiles of eolian earthy red silty clay and loess of the middle of the Late Miocene to Holocene age have been studied and correlated.A complete summary profile with projected isotopic ages and fossil-bearing beds has been assembled.The profile is subdivided into 12 stratigraphic units proceeding from the lower(older)to the upper(younger)one.The character of mammalian assemblages contained in each unit was analyzed and the corresponding pa-leo-climatic environments were deduced.The environmental character of each period and the change from the middle of the Late Miocene at about 8.0 Ma B.P.up to the Holocene progressed from the hot semiarid and semi-moist,warmer-moist,warm-moister of the Late Miocene.To slightly less warm moist,cool-dry,slight-warmer-moister of the Pliocene;later the cool to cold dry periods alternated frequently with the mild semiarid and semi-moist periods of the Quaternary.Vegetation progressed from the grasslands with sparse woods,wooded shrub-grasslands and subtropical forest-grasslands of the Late Miocene age to sparse grasslands and dry grasslands of the Pliocene;and to sparse grasslands,dry grasslands and tundras of the Quaternary.The climate changes in the Neogene were of low-amplitute in a generally warm-humid background.Those of the Quaternary were of higher am-plitude with a longer phase.Cool or cold dry and slightly warm semiarid and semi-moist climates al-ternated on a generally cool-dry background.The tendency since the start of the Quaternary was the change to more northern and western shift in the Loess Plateau,with progressively cooler and dryer conditions.The dramatic uplift of the Qinghai-Xizang(Tibet)Plateau and the forming and expansion of the Arctic ice sheet might be the main reasons of the more pronounced changes in the Quaternary.
