The Floristic Geography And Distribution Pattern Of Magnoliidae In Gansu Province

This paper taking81districts and countys in Gansu Province as the research unit, Magnoliidae plants in Gansu Province were counted and studied on the basis of document consulting and field investigation, to explain the Species diversity, flora chactacteristic, geographic distribution of the Magnoliidae plants, which offer scientific reference and theoretical basis for further study of Species diversity, Flora characteristics, Species distribution pattern, Diffusion evolution of Gansu province.The main research results of this paper as below:1) Species diversityThere are14000species (including infraspecies taxon) of Magnoliidae plants belonging to39families and490genera in the World. There are2745species (including infraspecies taxon) of Magnoliidae plants belonging to26families and195genera in the China. There are440species (including infraspecies taxon) of Magnoliidae plants belonging to20families and80genera in Gansu Province. The family number of this region account for respectively76.92%,51.28%of that of the world and china; The genus number of this region account for respectively41.03%,16.33%of that of the world and china; The species number of this region account for respectively16.45%,3.26%of the world and china.2) Floristic analysisThere are6dominant families (Ranunculaceae, Circaeasteraceae, Fumariaceae, Lauraceae, Papaveraceae, Lardizabalaceae), which total55genera391species (including varieties), the genus and species number of dominant families account for respectively68.75%,88.41%of that in Gansu Province. There are6characteristic families(Lardizabalaceae,Ranunculaceae,Schisandraceae,Fumariaceae,Circaeasterace ae, Sabiaceae) in Gansu Province.There are2families of Cosmopolitan distribution;9families of tropical distribution, which total26genera63species (including varieties); and9families of temperate distribution, which total27genera139species (including varieties). The temperate element occupied absolutely dominant position.3) Genus analysisThere are8dominant genus(Clematis,Berberis,Corydalis,Delphinium, Thalictrum, Ranunculus, Aconitum, Anemone), which total280species (including varieties), the dominant genus and its species number account for respectively10%,63.64%of that in Gansu Province. There are7characteristic genus(Halerpestes, Akebia, Souliea, Chloranthus, Schisandra, Thalictrum, Meconopsis) in Gansu Province.There are42monotypic genus, and it account for respectively52.5%of that in Gansu Province; There are42genus endemic to China. The abundance of monotypic genus and endemic elements reflect that the origin antiquity of Magnoliidae, and it also reflect that the complex habitat conditions, species divergence in Gansu Province.The abundance of temperate genus total49genera281species, the number of temperate genus account for respectively66.22%of that in Gansu Province. It reflect that the temperate properties of the flora were obvious. The tropical distribution genus total18genera49species, the number of tropical genus account for respectively24.32%of that in Gansu Province. It is obvious that the flora of Gansu has certain origin relationship with tropical and subtropic elements.4) Distribution pattern analysisThe south of Gansu province is the distribution centres of tropical-types families of Magnoliidae in Gansu province, and the central Loess Plateau is the north limit line. The distribution of temperate families in Magnoliidae is mainly in the Longnan mountain forest, the lowest region in the central Loess Plateau.The central Loess Plateau is the main distribution area, and Wen county, Kang county, Cheng county is the distribution centres of tropical-types genus of Magnoliidae in Gansu province, the North Qinling Orogenic Belt and the upper-middle of the Tao River is the north distribution limits.It is basis on the number of Species, the Magnoliidae plants has divided into4geographical distribution:The richness of Magnoliidae species is the highest as the Bailongjiang valley, the upper-middle reaches of the Tao River. The richness of Magnoliidae species is the second as the Western-middle part of the Longnan mountain forest, the eastern-middle part of the Gannan Plateau, the eastern-middle part of the Qilian Mountains. The richness of Magnoliidae species is the third as the western section of Qilian Mountains, the western Hexi Corridor, the Loess Plateau of Longdong. The Species richness is lowest of Magnoliidae as the central Loess Plateau.The result of Ranunculaceae geographic distribution patterns was found that, compared Ranunculaceae to Magnoliidae, although in specific distribution pattern is different on the detail, but it has reflects that they have the consistent about Species distribution distribution on the overall consistency.The analysis of genera endemic to China has reflects that, the southeast of Gansu Province is the main area of the distribution, and the Wenxian county is distribution center.The distribution pattern of Magnoliidae cause is very complex, including the ancient geological conditions, the complex and varied terrains and landforms, the climate conditions, the water and heat conditions. There are another reason have the Significant influence on the distribution pattern of Magnoliidae.