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连栽对桉树人工林下物种多样性的影响 被引量:108

Effects of continuous cropping on understorey species diversity in Eucalypt plantations.
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摘要 采用时空序列和定位监测相结合的方法,对广西国有东门林场桉树人工林的物种多样性及其维持机制进行了研究.结果表明,桉树连栽导致人工林植物多样性减少,在667 m2样方内,第2代林的植物种类比第1代林减少了54.43%;对18块4 m2样方监测(1998~2003年)结果,第2代林植物多样性比第1代林减少了50%,物种丰富度和Shannon-Wiener指数分别比第1代林减少39.39%和17.76%.桉树人工林连栽导致群落物种多样性降低,改变了群落的物种组成及特征.不同连栽代数群落的生活型谱存在明显差异,第1代林以小高位芽、藤本高位芽和矮高位芽植物为主,而第2代林则以草本高位芽植物、地上芽植物为多;第1代林的k-对策种和r-对策种分别为69.32%和30.68%,第2代林则分别是47.83%和52.17%,可见连栽使草本植物、地上芽植物和r-对策种的数量增加,木本植物和k-对策种的数量减少.可以认为,土壤中种子库和营养体对物种多样性维持有重要作用,提出了桉树人工林群落物种多样性维持机制的初始植物繁殖体组成假说.在一个经营周期内(6~7年),桉树人工林维持的植物多样性的高低取决于初始植物繁殖体组成的丰富程度,高强度干扰的连栽方式使某些高竞争力的物种或仅以种子(果实)传播的物种丧失,造成下一代林地初始植物繁殖体组成多样性的降低,从而使连栽林地的物种多样性逐代减少. By the methods of time-space series analysis and field monitoring, this paper studied the species dlversity and its maintaining mechanism in Dongmen Eucalypt plantations of Guangxi. The results indicated that during the period of 1998--2003, continuous cropping of Eucalyptus plantation resulted in a reduction of species diversity. The plant species number of second generation was reduced by 54.43 % in a 667 m^2 plot, and by 50 % in 18 sampling plots (each of 4 m^2), and the species richness and Shannon-Wiener index of 6-year second generation forest decreased by 39.39 % and 17.76 %, respectively, compared with the first generation. The continuous cropping not only decreased the species diversity, but also changed the species composition and characteristics of the community. Life-form spectra of Eucalypt plantations varied with generation. The plant life-form consisted of microphanerophytes. liana phanerophytes, and nana-phanerophytes in the first generation, while the herbaceousphanerophytes and chamaephytes occurred in the second generation. The k-strategy and r-strategy species accounted for 69.32 % and 30.68 % in the first generation, while 47.83 % and 52.17 % in the second generation, respectively. Therefore, continuous cropping of Eucalypt plantations was advantage for herb, therophytes and rstrategy species, but disadvantage for woody plants and k-strategy species. Seed band and vegetative body in soil were considered to play an important role in maintaining diversity. A new hypothesis, initial plant Diaspora, on the maintaining mechanism of species diversity in Eucalypt plantation was put forward.
出处 《应用生态学报》 CAS CSCD 北大核心 2005年第9期1667-1671,共5页 Chinese Journal of Applied Ecology
基金 国家教育部留学回国人员科研启动基金项目(1997-832) 广西教育厅科研资助项目.
关键词 桉树人工林 物种多样性 连栽 维持机制 初始植物繁殖体组成假说 Eucalypt plantation, Species diversity, Continuous cropping, Maintaining mechanism, Initial plant Diaspora.
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