5种川西北沙化地草本植物生态适应策略的差异性

摘要

In the study,five species of natural herbs in the desertified grassland of northwest Sichuan,including Carex praeclara,Leymus secalinus,Orobanche coerulescens,Carum carvi and Astragalus bhotanensis,were selected to determine their adaptation strategies and mechanisms to desertification habitat by measuring appar-ent traits,water content,biomass and its allocation ratio,and analyzing the response of growth and develop-ment and resource allocation of different herbs to desertified habitats.The results of this study showed that ap-parent traits were extremely significant difference among five species of herbs(P<0.01),in which O.coerules-cens and C.carvi adapted to desertification habitats by encouraging the sexual reproduction,however C.prae-clara,L.secalinus and A.bhotanensis adapted to desertification habitats through crowns,rhizomes,and deep roots,respectively.Water content and its allocation proportion also were extremely significant difference a-mong five species of herbs(P<0.01),in which the water content of C.praeclara,L.secalinus and A.bho-tanensis preferentially assigned to reproductive branches,but O.coerulescens had priority to stems and leaves, and C.carvi used the water allocation with relative balance.Biomass and its allocation proportion showed aex-tremely significant difference among five species(P<0.01),indicating that the biomass of C.praeclara,L. secalinus,O.coerulescens and A.bhotanensis preferentially allocated to rhizomes,stems and leave,reproduc-tive branches,and roots,respectively;however,C.carvi allocated the biomass to each component with rela-tive balance.These suggested that five species of psammophytesshowed a difference strategies to trade off re-source allocation and they obtained or allocated the limited available resources to increase the adaptability to habitat through varieties of phenotypic plasticity,water using ability and biomass allocation,etc.%以5种川西北沙化草地自然留存植物沙生苔草(Carex praeclara)、赖草(Leymus secalinus)、紫花列当(Oro-banche coerulescens)、藏茴香(Carum carvi)和地八角(Astragalus bhotanensis)为研究对象,通过测定5种草地植物的表观性状、构件含水量和生物量及其分配,分析5种植物的生长发育、资源分配对沙化生境的响应差异,探讨5种植物对沙化地生境的应对策略与适应机理.结果表明,1)5种植物的表观性状具有极显著差异(P＜0．01),沙生苔草通过冠幅,赖草通过根茎,地八角通过深根系,紫花列当和藏茴香通过扩大有性生殖来适应沙化生境.2)5种植物的含水量及其配比均存在极显著差异(P＜0．01),沙生苔草、赖草和地八角的水分优先分配到生殖枝,紫花列当优先分配到茎叶,藏茴香则采用相对均衡的水分分配方式.3)5种植物的生物量及其分配也存在极显著差异(P＜0．01),沙生苔草生物量优先分配到根茎,赖草优先分配到地上茎叶,紫花列当优先分配到生殖枝,地八角优先分配到根部,而藏茴香则相对均衡的分配生物量到各构件.5种沙生植物对资源权衡分配的方式不同,但均能通过表型可塑性、水分利用能力和生物量分配等应对策略来获取或分配有限的可利用资源,增加其对生境的适应性,得以在沙化草地中留存下来.