喜旱莲子草营养繁殖特征对干扰的响应  

Vegetative propagation characteristics of Alternanthera philoxeroides in response to disturbances

作　　者：贾昕[1,2] 杨兴中[1] 潘晓云[2] 李博[2] 陈家宽[2] 

机构地区：[1]西北大学生命科学学院,西安710069 [2]长江河口湿地生态系统野外科学观测研究站,生物多样性和生态工程教育部重点实验室,复旦大学生物多样性科学研究所,上海200433

出　　处：《生物多样性》2008年第3期229-235,共7页Biodiversity Science

基　　金：国家自然科学基金(30400052);国家重点基础研究发展规划(973)项目(2006CB403305)

摘　　要：养分富集和物理干扰是人类活动影响下外来植物在入侵地所面对的重要生境特征,而克隆生长和营养繁殖是外来植物入侵高资源干扰生境的重要生活史特征。喜旱莲子草(Alternanthera philoxeroides)是一个世界性的入侵种,它主要分布于暖温带-亚热带气候区各种淡水生态系统的水陆交界区域,这些生境易受养分富集和物理干扰的影响。喜旱莲子草在入侵地有性繁殖缺失,因而贮藏根形成、根芽萌发和分株生长等是其重要的生活史环节和营养繁殖特征。本文中通过种植实验研究了喜旱莲子草的营养繁殖特征对养分增加和物理干扰(贮藏根片段化和埋藏)的响应。结果表明:(1)高养分条件下喜旱莲子草的总生物量增加了约1.5倍,贮藏根分配(营养繁殖分配)增加了约15%,贮藏根平均长度增加了约1.5倍;(2)喜旱莲子草的根芽萌发数随贮藏根段大小的增加而增加,平均每克贮藏根(干重)能够萌发出约15个根芽,萌发出1个根芽只需要不到0.1g的贮藏根,埋藏深度不影响根芽萌发数;(3)贮藏根段大小和埋藏深度对喜旱莲子草分株的主枝长和平均相对生长率均没有显著影响。这些结果暗示,喜旱莲子草的营养繁殖特征对养分富集和物理干扰非常适应,能够促进其局域种群的快速增长和流域范围内集合种群的长期续存。In the context of increasing anthropogenic activities, nutrient enrichment and physical disturbances are among the most important environmental factors influencing biological invasions. On the other hand, clonal growth and vegetative propagation are considered important life history traits promoting the invasiveness of plants in high-resource and disturbed habitats. Alternanthera philoxeroides, endemic to South America, is an amphibious clonal weed invading areas worldwide. It is widely distributed in warm-temperate and subtropical regions, and tends to invade nutrient-rich and disturbed habitats such as riparian zones, wetlands, and arable areas. Throughout its introduced range, A. philoxeroides rarely produces viable seeds and reproduces mainly by vegetative propagation via storage roots and stems. Therefore, formation of storage roots, sprouting of root buds, and growth of new ramets are crucial characteristics in the life history of A. philoxeroides. We conducted three container experiments to examine the responses of vegetative propagation characteristics ofA. philoxeroides to two factors-nutrient addition and physical disturbance （two types of physical disturbance： fragmentation and burial of storage roots）. Nutrient addition increased total biomass and mean length of storage roots 1.5-fold, and biomass allocation to storage roots by 15% （i.e., vegetative reproductive allocation）. Number of root buds increased by approximately 15 sprouts per g （dry mass） of storage root. Burial depth had no effect on number of sprouts per root fragment. Neither storage root size nor burial depth affected main stem length or mean relative growth rate of ramets. Our results suggest that adaptation of vegetative propagation characteristics to nutrient enrichment and physical disturbances may enable local A. philoxeroides populations to grow rapidly, and contribute greatly to the persistence of metapopulations at the watershed scale.

关 键 词：根芽 克隆生长 生物量分配 生物入侵 外来入侵植物 物理干扰 养分富集 营养繁殖体库 

分 类 号：Q948[生物学—植物学]