Study On The Relationship Between Pollen Assemblages In Topsoil And Modern Vegetation In The Typical Karst Rocky Desertification Area

The karst areas are characterized of vulnerable envrioments which lie at the intersection where atmosphere, water shpere, creature sphere and human activities converge at. The soil here has special features such as shallow soil thickness,discontinuity of soil distrubution, lack of C horizon, lack of sTableility, in a state of negative growth in amount and in a state of non-renewable nature compared with the low rate of soil process.Irrational land-use patterns superimposed on the fragile karst ecosystem, causing serious decline in soil quality and land productivity. The ecological environment in desertification areas of rehabilitation and reconstruction, most of them focused on the hydrological, ecological and other aspects of soil, pollen studies have been vacancies. Therefore, desertification regions in a typical modern vegetation and pollen study of the relationship of desertification areas in the comprehensive treatment, rehabilitation and reconstruction of the natural ecological environment has very important significance.This study selected Chongqing vegetation well preserved karst mountains, a typical karst mountain vegetation restoration and modern vegetation damage typical of the more serious desertification areas of different vegetation types, pollen analysis of the relationship between modern vegetation.1) Through survey and sampling to 14 different vegetation types' topsoil of Mt.Jinfo Nature Reserve,Chongqing, to study the features of the spore-pollen assemblage. The results show that:the spore-pollen is composed of 106 genus, among which, coniferous tree pollen, ferns spore and broad-leaved tree pollen dominated contents were 8.94～56.30%,19.73～46.77% and 6.17～39.28%, the shrub pollen and herbs pollen takes the 2nd place with the content were 6.24～29.77% and 5.58～18.24%, and the marsh grass pollen the least,is only found in a small amount of JFS-5 (0.14%).Study area at different vegetation types of the basic characteristics of surface spore-pollen assemblages reflects the local current plant composition, appearance and vertical distribution of vegetation, to better reflect the basic characteristics of mountain communities.2) The spore-pollen analysis of surface soil and vegetation investigation in five typical of communities (slope farmland,1-year abandoned farmland,bush-grass land,15-year scattered woodland and 25-year woodland) which represent the different period of vegetation restoration showed that:(1) 46 pollen taxa are recorded totally, among which, herbs and ferns are dominate with 57.61%～95.06%,then the trees(mainly Cedrus deodar a and Pinus massoniana) with 2.53～21.31%, and the shrub pollen is only about 1.04～8.88%, indicating the character of a serious degradation of local vegetation; (2) Abundance of pollen types is not change obvious in the recovery procedure various stages, the species mainly represented by the taxa changes of ferns, shrubs and shrubs; (3) Pollen assemblages are obvious differentiation during the typical vegetation restoration in karst mountain, which corresponding to the actual vegetation and reflecting the present conditions of the modern vegetation in karst mountain, indicating pollen analysis can give a reference to the rehabilitation and reconstruction of natural environment in the study area.3) The pollen analysis of 25 topsoil and mosses samples under six typical of vegetations in the rocky desertification area showed that:(1) 47 pollen taxa are recorded totally, among which, herbs and ferns are dominate with 23.62～76.47%, then the trees (mainly Pinus massoniana) with 17.73-74.05%, and the shrub pollen is only about 0.00～12.50%, indicating the character of a serious degradation of local vegetation; (2) Pollen assemblages are obvious differentiation under different vegetations, which corresponding to the actual vegetation and reflecting the present conditions of the modern vegetation in the rocky desertification area. Surface spore-pollen assemblage has a lot of hi-lime, dry by nature, stone endogenous plants, ecological restoration and reconstruction have a good indication to, for the rehabilitation and reconstruction of the area of natural environment gives a reference.Through to Chongqing vegetation on well-preserved karst mountains, vegetation in karst mountain during different restoration period of typical vegetation community, the more serious destruction of the modern vegetation of different vegetation types typical of rocky desertification pollen and the relationship between modern vegetation studies reveal the different karst areas Stage of pollen differences, the overall governance for the desertification areas, rehabilitation and reconstruction of the natural environment provide a reference basis.