城市化地区河岸带植被特征及其与河岸硬度的关系——以晋江市为例

确立了滨河河道硬度与滨河土地硬度两个指标,用以研究城市化地区河岸带的植物构成、多样性与均匀度、优势植物等特征与河岸硬度的关系。选定晋江市都市区12条主要河流作为研究对象,通过样地调查收集数据,并采用相应指数进行数据处理分析,结果表明:(1)调查河流的河岸带植被物种共计70科143属159种,其中乔木20科30属41种,灌木15科15属20种,草本35科98属98种,草本居主导地位,河流间种类分布不均衡;(2)河岸带植物乔灌草区系均以广义热带性成分居多,其次为世界性成分、温带性成分,无中国特有分布类型,乔木中广义热带成分占绝对主导,直观反映地带性特征,灌木与草本中的温带成分多于乔木中的温带成分,类型趋于多元,种类更丰富;(3)从河岸植被优势植物构成来看,主要优势乔木与灌木基本为本土植物,而主要草本中外来植物入侵严重,对地带性植物景观的指示显然不及乔木与灌木;(4)从河岸植被的人工美学属性来看,灌木优势植物中园林观赏植物的种类数显著多于乔木、草本优势植物,反映出晋江人工审美主导的滨河景观空间主要改变与塑造了灌木层植被景观;(5)从河岸植物的人居需求属性来看,龙眼、杨桃等多见于庭院林、水岸林的水果树种也在河岸植被中频繁出现,反映出人口密集区由于对植物生产用途的重视而对河岸植被产生的影响;(6)滨河土地硬度与河道硬度对河岸带灌木植物的影响最强烈,二者均对河岸带植物多样性造成威胁,且前者具有更大的影响力,而后者直接影响了河岸植物的分布形态,出于生产与审美目的的人为干扰对河岸带植物优势种的影响力随滨河硬度的增加而加强,低滨河硬度有助留存原生植被群落;(7)天然弯曲的河流形态对河流植被特征具有积极影响,有助于保留更多本土植被类型,并能在某种程度上丰富乔灌草的植物种类,但这种缓和作用无法根本扭转河岸硬化对植物多样性的胁迫影响。研究表明,城市化地区河流的岸带植被特征与沿线人为干扰类型和强度密切相关,恢复与塑造河岸生态景观要以乡土植被为主,通过乔木景观塑造地带性景观,并以灌木与草本丰富植被景观。

Relationships between riparian vegetation and shoreline hardness for urban rivers: a case study in Jinjiang City, Fujian Province

We investigated the relationships between riparian vegetation composition, diversity, evenness, and dominant species, and shoreline hardness (bank and land hardness). Twelve major rivers in Jinjiang City were targeted. Data were collected from a site survey and were processed with the corresponding indexes. The results showed the following:(1) There were 159 plant species from 143 genera and 70 families, including 41 trees from 30 genera and 20 families, 20 shrubs from 15 genera and 15 families, and 98 grass species from 98 genera and 35 families. There was an uneven distribution of plant species among the different rivers, but grass species were consistently the dominant class of riparian vegetation; (2) Riparian floras were mainly tropical types, followed by cosmopolitan and temperate types; however without the specific type of China. Tropical trees were consistently the dominant tropical flora and directly represented geographic conditions. There were more temperate shrubs and grasses than trees, and, in general, there was a greater diversity of species for the temperate type than for the tropical and cosmopolitan types; (3) In terms of composition, the dominant trees and shrubs along the rivers were domestic plants. In contrast, the dominant herbs were foreign plants, and therefore, compared to trees and shrubs, herbs did not represent the typical landscape characteristics of the region; (4) In terms of aesthetics, there were considerably more ornamental shrubs than trees or grasses, which indicated that the river landscape designed by Jinjiang City had altered the composition of the shrubs, but not the trees or grasses; (5) In terms of living demand for the riparian vegetation, longan and starfruit, which are commonly found in courtyards, frequently appeared along the riverbanks, which indicated that in densely populated areas, cultivated plants have an influence on the composition of riparian vegetation; (6) For the Bin River, land and bank hardness had a greater effect on shrub composition than on tree and grass composition, and, overall, posed a threat to riverbank plant diversity. A greater effect on composition was noted for land hardness than for bank hardness, while the latter had a direct influence on the distribution of plants along the riverside. In terms of production and aesthetics, the influence of the artificial disturbance was stronger on the plants along the riverside with the land hardness of the Bin River. In general, low hardness supports the preservation of the original vegetation of the riparian community; and (7) Curved rivers had positive effects on vegetation. Curved rivers had higher local vegetation diversity and a richer variety of shrubs. However, the loss of flora diversity, due to riverbank hardening, was also present for curved rivers. Overall, the difference between rivers within the same climate zone is closely linked with the type and intensity of artificial disturbance of the shoreline. In order to restore and reshape the ecological landscape of the riverbanks, the landscape design should be based on the local conditions and demand; the majority of plants should be local vegetation, while the trees should be designed as the zone landscape, and shrubs and grasses should be used to enrich the diversity of the vegetation.