Analysis Of Structural Traits Of Riparian Forest In Plain Area In Beijing

Forest structure is the most important and basic feature of forest ecosystem.Studying the structural characteristics of forests is a prerequisite for exploring forests,as well as an important link in the analysis of forest conditions.In order to provide reference for the construction and management of urban riparian forests in the future,This study took the riparian forests constructed in the Green Corridor Project-"Wu He Shi Lu" in Beijing as the research objects.First we investigated 3 different functional types and 3 different riparian types of forests,and then analyzed the composition structure characteristics from the species and size,and the space structure characteristics from vertical direction and horizontal direction.After that,we studied the structural differences between different types of forests,and finally discussed the reasons for the difference and the forests' influences on the environment.The main results and conclusions were summarized as follows:(1)The most widely used tree species in the riparian forests of Beijing were concentrated in a few species,especially the Salicaceae,whose important values also occupied a dominant position.However,the use of several tree species in such a large scale will lead to a single landscape.The frequency of 87.5%shrubs was lower than 10%.Although the proportion of native arbors and shrubs was relatively high,there were fewer types of native trees,whereas native herbs were lower both in proportion and quantity.The ornamental species were more but fewer in number indicating that the existing number of landscape trees has no obvious effect on the improvement of landscape.The protection riparian forest had fewer scenic seasons than the landscape-protection and the recreation riparian forest did.(2)The diversity indices of arbors,shrubs and herbs were disturbed widely by human activities,changed differently in different functional types and different riparian types.In general,herbaceous diversity index was higher than trees' and higher than shrubs'.The distance of the settlement area was positively correlated with the number of species,the richness index and the diversity index,and had a significant positive correlation with the evenness index.(3)In the three functional types of forests,the tree diameter,tree height,and crown width all had a lognormal distribution.In general,the individual trees were small showing that the cultivation of big trees will be the main goal in the future.(4)The area ratio of arbors,shrubs and herbs of the riverside forests in Beijing was a large gap with the reasonable values.The structure of existing riparian forests were mostly double-layer or single-layer,indicating that the riparian forest with complex structure needs to be constructed.The horizontal aggregate index value of all the samples of the protection riparian forests were greater than 1,in which the arbors distributed uniformly and presented serious artificiality,resulting in a poor ornamental effect.