An Ecological Study On Wetland Vegetation In Lijiang River Of Guilin

River Wetland is a typical ecosystem transition zone. River Wetland vegetation is the important component of River Wetland ecosystem. River Wetland vegetation have many important aesthetic and social-economic functions as well as ecological function, such as protecting river shore system, stabilizing soil-water, percolating sediment, conserving stream water quality, and promoting biodiversity conservation. The structures, functions and eco-characteristics of the River Wetland vegetation do not only reflect the fundamental features and functions of wetland ecosystem, but also indicate the ecological environment condition and the quality of wetland eco-environment. There are various vegetations which are adapted to different wetland eco-environments. Based on the application of the theories and methods of synecology, This paper systematically discussed and analyzed the compositions, floras, classification systems, community characters, distribution characteristics, utilization and conservation of wetland vegetation in LijiangRiver of Guilin.1. The Quadrat method and the route survey method were used to study the wetland vegetation in Lijiang River, in which a total of 231 quadrats were investigated. Based on field investigation data and referring to the related literatures, a list of plant species in the composition of wetland vegetation i n LijiangRiver was proposed. And analysed the flora of these plant species. According to the classified principle and taxonomic unit in"China wetland vegetation", the classification system of the wetland vegetation in Lijiang River was put forward. The features of the main community types were described which combined with habitat characteristics. Maps showing ecological series of wetland vegetation which come from the center to the river banks direction were investigated by line transaction in 17 sampling transects. Then, the characters of vegetation series were analyzed.2. There are 157 major species composition of wetland vegetation in Lijiang River, belonging to 125 genera and 56 families, including 9 arbor species,23 shrub species and 125 herbaceous plants. There are 4 families and 4 genera and 4 species of pteridophyte,1 family and 1 genus and 1 specie of gymnosperm,51 families and 120 genera and 152 species of angiosperm, and Poaceae, Polygonaceae, and Compositae were the dominant genera, which respectively account for 11.46%,10.19% and7.01%. The species composition of wetland vegetation in Lijiang River is complex, which include the humidogene, aquatic plant and some mesophyte plant. In LijiangRiver wetland vegetation flora compositions, there are 5 types and 2 subtypes of the distribution of the seed plants families,12 types and 10 subtypes the distribution of the genera. The compositions of families and genera flora are mainly distributed in pan-tropic.3. The Wetland vegetation in Lijiang River were classified by 5 wetland vegetation type groups such as coniferous forest, broad-leaved forest, shrub, herbosa and shallow water plants, and by 10 wetland vegetation types, such as deciduous coniferous forest, deciduous broad-leave forest, evergreen broad-leave forest, deciduous broad-leave shrub, sedge, graminoid, forb, submerged plant, leaf-floated plant and floating plant, in which can be categorized into 28 formations, such as Form. Pterocarya stenoptera, Form. Adina rubella, Form. Eichhornia crassipes ect..4. Wetland vegetation is mainly distributed in the shallow water area, flood plain, river island and river bank in Lijiang River wetland. The submerged plant communits are dominant in the aquatic plants in the shallow water area. Any of various chiefly form. Vallisneria natans, form. Potamogeton wrightii, form.Hydrilla verticillata, form. Egeria densa, form. Vallisneria asiatica, Hygrophilous communities are mainly distributed in the flood plain and river island. There are mainly graminoids such as Cynodon dactylon, Panicum repens ect., sedges such as Kyllinga monocephala, Carex nemostachys ect., forbs such as Polygonum hydropiper,Lobelia chinensis, Hydrocotyle sibthorpioides var. batrachium ect., hygrophilous shrubs such as Salix chaenomeloides and Adina rubella. Semi-hygrophilous communities are distributed in the zone farther away from the water, including flood plain, river island and river bank. Celosia argentea. Xanthium sibiricum, Mosla scabra, Vitex negundo var. cannabifolia, Pterocarya stenoptera art Semi-hygrophilousplants which were distributed in flood plain and river island. And the vegetation of river bank is mainly composed of arbor, but the arbor specice is single, which belong to Pterocarya stenoptera. In addition, there are a few Cinnamomum bodinieri growing on the river bank.5.Along the 17 sampling transects the distribution of plant community mainly presented in the following ecological series of "aquatic plantâ†'ygrophilous plantâ†'semi-hygrophilous plant" under the impact of surface water level in the Lijiang River wetland. It reflects the shoreward zonation of the wetland vegetation. Three kinds of ecological series are avaliable for the Lijiang River wetland. They are â‘  submerged plant â†' floating plant â†' hygrophilous plant â†' semi-hygrophilous; â‘¡ submerged plant â†' hygrophilous plant â†' semi-hygrophilous; â‘¢ hygrophilous plantâ†'semi-hygrophilous.6. There are abundant plant resources of wetland vegetation in Lijiang River. According to its functional role divided them into three categories, such as including species to environmental protection, species to economic production and species to scientific and cultural value. And which can be divided into 13 subcategories, such as the reducing pollution plant, the water and soil conservation plant, the green manure plant, the indicator plant, the edible plant, the medicinal plant, the forage plant, the fiber plant, the energy plant, the oil plant, the ornamental plant, the pioneer plant and the rare and endangered plant. Currently these resources are widely used in forage, fertilizer, bank revetment and landscape.7. The innovation of this paper:The article takes Wetland vegetation in Lijiang River as its research object. Based on the application of the theories and methods of synecology, this paper took a more comprehensive investigation of species composition and floristic characteristics in the wetland vegetation in Lijiang River. The classification system of the wetland vegetation in Lijiang River were put forward for the first time and the gradient change rule of the wetland vegetation in Lijiang River were put forward by drawing ecological series. With comprehensive and systematic backgroud data of wetland vegetation,which could provide a theoretical basis for the utilization, protection, management, restoration and Landscape Planning.