MORPHOLOGICAL CHARACTERISTICS AND BIOMASS ALLOCATION OF LEYMUS CHINENSIS (POACEAE) (TRIN.) RESPONSES TO LONG-TERM OVERGRAZING IN AGRO-PASTORAL ECOTONE OF NORTHERN CHINA
Y. Zhang, X. Shao, C. Chen, Y. J. Zhang and K. Wang
Institute of Grassland Science, College of Animal science and Technology, China Agricultural University, West Road No.2 Yuan Ming Yuan, Haidian District Beijing, 100093, P.R. China
Corresponding Author e-mail: email@example.com
Overgrazing is the determinant factor to cause degradation and desertification of grazed grasslands in China. Leymus chinensis (Poaceae) (Trin.), the dominant grass in grassland of northern China, may exhibit distinctively strategies to survive under long-term overgrazing condition. In this study, we quantified its changes of morphological plasticity, biomass and biomass allocations when the long-term overgrazing activity was removed. A grazing-free plot and an overgrazed plot (without overgrazing stress during the experimental year) were established in the study area. Six quadrats were randomly selected in each plot for measurements. Results showed that when long-term overgrazing stress was removed, the number of vegetative shoot restored to normal level, while the plant height, leaf number, leaf length and breadth, reproductive shoot number, and biomass were still at a lower level. And the biomass allocation patterns differed significantly (P<0.05) between tested treatments. After long-term overgrazing activity, L. chinensis allocated more biomass of total biomass to below-ground, less biomass of above-ground to reproductive shoots compared to L. chinensis under grazing-free condition. These modified morphological characteristics and biomass allocations were adaptive strategies of L. chinensis induced by overgrazing, and rapid recovery of vegetative shoot number was an occupational strategy of L. chinensis to restore.
Key words: Leymus chinensis, overgrazing, morphological characteristics, biomass, biomass allocations, restore.