Chin J Plant Ecol ›› 2010, Vol. 34 ›› Issue (3): 348-358.DOI: 10.3773/j.issn.1005-264x.2010.03.012

• Research Articles • Previous Articles    

Compensatory growth of Carex scabrirostris in different habitats in alpine meadow

ZHU Zhi-Hong1,*(), XI Bo1, LI Ying-Nian2, ZANG Yue-Ming1, WANG Wen-Juan1, LIU Jian-Xiu1, GUO Hua1   

  1. 1College of Life Sciences, Shaanxi Normal University, Xi’an 710062, China
    2Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
  • Received:2009-02-17 Accepted:2009-08-12 Online:2010-02-17 Published:2010-03-01
  • Contact: ZHU Zhi-Hong


Aims Compensatory growth is affected by defoliation ratio, water and soil nutrient availability, but it is unclear which factor is most important in the overcompensatory response to herbivores in a particular area. Our objectives were to examine how compensatory growth of Carex scabrirostris varies with different habitats in an alpine Kobresia humilis meadow and determine relative effects of these factors on compensatory growth.

Methods Our field experiment at the Haibei Research Station of the Chinese Academy of Sciences from April to September 2007 included three habitats (habitat I: pen pasture, grazed × high nutrient availability; habitat II: pass pasture, grazed × low nutrient availability and habitat III: ungrazed pasture, null defoliation ratio × low nutrient availability) with three plots per habitat. In each plot, 12 quadrats (0.5 m × 0.5 m) were divided into two groups: 6 caged and 6 uncaged. For each of these sets of 6 quadrats, 3 quadrats were sampled in mid-June and 3 in mid-August. We used canonical correspondence analysis (CCA) with potential impact factors selected by the forward selection procedure for the compensatory growth of C. scabrirostris ramets to determine the relative effects of defoliation ratio, water and soil nutrient variables on compensatory growth.

Important findings The compensatory increase in dry weight, cover, density and height of ramets were higher for the habitat I than for habitats II and III. Overcompensation of aboveground biomass per ramet occurred in habitat I and II, whereas undercompensation was found in habitat III. The biomass allocation to growth function per ramet in habitat I was equal to that of III but higher than that of II. Storage allocation was greatest in habitat II, moderate in III, and least in I. Storage allocation was negatively correlated with growth and clonal propagation allocations, and growth allocation was negatively correlated with sexual reproductive allocation. The most important factors that induced compensatory growth were relative growth rate and soil organic matter content in June, followed by nitrogen content in August and defoliation ratio. These results suggest that the ramets in nutrient-rich habitat or in nutrient-poor habitat but having a high storage allocation tend to have overcompensation growth. The nutrient-rich habitat can compensate for the negative effects of herbivores and improve the ability to tolerate herbivores.

Key words: clonal plant, compensatory growth, grazing, resource availability, alpine meadow