Differences of ecological adaptation strategies of 5 herbs from the desertified grassland in the northwest Sichuan

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 apparent traits, water content, biomass and its allocation ratio, and analyzing the response of growth and development and resource allocation of different herbs to desertified habitats. The results of this study showed that apparent traits were extremely significant difference among five species of herbs(P<0.01), in which O. coerulescens and C. carvi adapted to desertification habitats by encouraging the sexual reproduction, however C. praeclara, 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 among five species of herbs(P<0.01), in which the water content of C. praeclara, L. secalinus and A. bhotanensis 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 aextremely 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, reproductive branches, and roots, respectively; however, C. carvi allocated the biomass to each component with relative balance. These suggested that five species of psammophytesshowed a difference strategies to trade off resource 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.