廣州城區生態安全島典型植物群落的結構及物種多樣性研究

以廣州城區生態安全島典型的自然和半自然型植物群落為研究物件，通過樣方調查，對物種組成、區系成分、群落結構、珍稀瀕危種、物種豐富度和多樣性等要素進行了初步研究，結果表明：廣州城區6處生態安全島3.238hm2的調查樣方中，共記錄到維管束植物145科342屬495種，熱帶亞熱帶區系特徵明顯。不同保護級別的珍稀瀕危植物6科7屬7種；群落垂直結構複雜，喬木層一般都能劃分亞層。物種豐富度Partrick指數值在22—100之間變化、Shannon-Wiener多樣性指數值在0.3861—3.0901之間變化、Simpson優勢度指數值在0.1380—0.9261之間變化以及Pielou均勻度指數值Jsw在0.1289—0.9427之間變化，相似性係數S和Bray-Curtis指數存在一定差異。目前廣州城區生態安全島的植物群落隨著正向演替的進行，物種多樣性在不斷增加。在區系上，生態安全島與具有南亞熱帶地帶性典型植被的鼎湖山聯繫較密切，雖然在物種多樣性方面尚有一定差距，但演替時間較長的生態安全島植物群落的物種多樣性已相當於鼎湖山南亞熱帶地帶性植被演替的後期階段。植被之間的空間距離、與城市中心距離的遠近等生境條件差異、人為干擾均對群落的物種多樣性產生影響。因此，需加強保護，才能在高度城市化的區域保存這樣一些具有地帶性頂級群落的結構和物種多樣性特徵的植物群落。

The community structure and species diversity of natural and semi-natural plant communities in six ecological safety islands, located in urban Guangzhou, were studied by the sample-plot survey method. The results show that 495 species belonging to 145 families and 342 genera were recorded in the six ecological safety islands, which have a total area of 3.238hm². Among the 495 recorded species, 30 species are ferns belonging to 19 families and 15 genera; 10 species are gymnosperms belonging to 6 families and 8 genera; 90 species are monocotyledon belonging to 27 families and 68 genera; 365 species are dicotyledon belonging to 93 families and 241 genera. The geographical elements of the genera are mainly composed of tropical and subtropical types. In addition, 7 rare and endangered species belonging to 6 families and 7 genera were recorded, which fall into different protection grades. The rare and endangered species were mainly found in fengshui forest communities. The communities in the middle and later stage of succession had a complex vertical structure and most of the arbor layer could be divided into sub-layers. The communities in the initial stage of succession had a relatively simple structure. The Patrick Index varied from 22 to 100, whilst the Shannon-Wiener Index varied from 0.3861 to 3.0901. Values of between 0.1380 and 0.9261 were observed for the Simpson Index, while the Pielou Index (J_sw) was between 0.1289 and 0.9427. A difference could be identified between the Sorenson Index and the Bray-Curtis Index. The Shannon- Wiener Index and the Patrick Index exhibited similar patterns, but the Simpson Index and the Pielou Index had different patterns. The index of β diversity showed that there was a high coefficient of community similarity among the fengshui forest communities. As the succession progressed, the β diversity of other communities would increase gradually. Plant communities in the ecological safety islands of urban Guangzhou are in positive succession with an increase in species diversity. As the distance between sample-plot and city center increases, the number of species, the proportion of native species, and the coefficient of community similarity also increase. In comparison with the typical southern subtropical zonal vegetation in Dinghushan, vegetation of the ecological safety islands in urban Guangzhou have similar floristic characteristics. In general, species diversity in the ecological safety islands of Guangzhou may not be as rich as that in Dinghushan. However, some communities in Guangzhou, with a longer succession history, have nearly reached the climax stage, with a rich diversity, and may be equivalent to the same stage in Dinghushan. Species diversity is affected by different habitat conditions, such as the spatial distance among vegetation patches, the distance between habitats and the city center, and human disturbance. In highly urbanized areas, by strengthening conservation, vegetation communities that have a similar structure and species diversity to the zonal climax community may develop. Copyright © 2011 中國科學院生態環境研究中心.