Chin J Plant Ecol ›› 2007, Vol. 31 ›› Issue (1): 83-92.DOI: 10.17521/cjpe.2007.0011

• Research Articles • Previous Articles     Next Articles

INTER-SPECIFIC COMPETITION BETWEEN TWO SUBMERGED MACROPHYTES, ELODEA NUTTALLII AND HYDRILLA VERTICILLATA

XU Jing-Wei1,2, LI Wei1,*(), LIU Gui-Hua1, ZHANG Li-Jing1,2, LIU Wen-Zhi1,2   

  1. 1Laboratory of Aquatic Plant Biology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
    2Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2005-12-27 Accepted:2006-05-14 Online:2007-12-27 Published:2007-01-30
  • Contact: LI Wei

Abstract:

Aims Elodea nuttallii and Hydrilla verticillata have similar morphology. E. nuttallii is an alien aquatic plant introduced into China in 1980s. Both species occupy similar habitat; therefore, they are potential competitors. We investigated: 1) weather inter-specific competition occurred, 2) which species had superior competitive abilities, and 3) what factors influenced competitive results.

Methods Two replacement series experiments were carried out to analyze interspecific competition between E. nuttallii and H. verticillata. In replacement series experiments, the planting densities of the two species were varied but the total density was held constant. The first experiment assessed competitive ability at two levels of soil fertility, and the second investigated the long-term competitive growth of E. nuttallii and H. verticillata.

Important findings E. nuttallii had superior cold resistance and advantages in competing for space-time during winter and spring, so it grew well in the long-term experiment and eventually replaced H. verticillata. In the short-term experiment, H. verticillata formed an upper canopy, giving it advantages in competing for light and occupying the water surface, causing imbalanced competition between H. verticillata and E. nuttallii. H. verticillata was the stronger competitor at both levels of soil fertility, and increased soil fertility could strengthen its competitive abilities; however, it could not replace E. nuttallii and they could coexist in the mixed population. This study suggests competitive abilities are integrated abilities of plants and those morphological traits, life history traits and environmental factors could affect the results of competition. Therefore, investigations of plant interactions should encompass a wide array of factors.

Key words: Elodea nuttallii, Hydrilla verticillata, competition, replacement series experiment, submerged macrophyte, soil fertility