Chin J Plant Ecol ›› 2011, Vol. 35 ›› Issue (9): 973-980.DOI: 10.3724/SP.J.1258.2011.00973

• Research Articles • Previous Articles     Next Articles

Effects of waterlogging on intraspecific interactions of the clonal herb Alternanthera philoxeroides

YU Guo-Lei()   

  1. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2013-03-17 Accepted:2014-06-22 Online:2011-03-17 Published:2011-09-01

Abstract:

Aims Plant-plant interaction is fundamental in plant ecology. Many studies have examined the effects of environmental factors such as light, nutrients and water on plant-plant interactions, but few have tested the effects of waterlogging. Our objective is to investigate the effects of waterlogging on intraspecific interactions and test the hypothesis that waterlogging can modify the type and intensity of intraspecific interactions.
Methods We grew plants of Alternanthera philoxeroides outdoors at three densities (1, 4 or 16 plants in one pot) and four levels of waterlogging severity (water levels of -20 (no waterlogging), 0, 20 or 40 cm). After three months, plants were harvested and data were collected.
Important findings With increasing plant density or waterlogging severity, growth of A. philoxeroides decreased significantly. However, the effect of density differed greatly under different levels of waterlogging severity. With no waterlogging, the effect of density on growth was negative and the competition intensity was high. With water levels of 0 and 20 cm, the density effect was still negative, but the intensity decreased. With a water level of 40 cm, however, the density effect was positive. Moreover, waterlogging severity significantly affected the relative neighbor effect and its values increased gradually from negative (under no waterlogging) to positive (in 40 cm). The results support a stress-gradient hypothesis and suggest that waterlogging can affect intraspecific interactions. With increasing waterlogging severity, intensity of competition decreases while that of facilitation increases.

Key words: competition, facilitation, plant-plant interactions, stress, stress gradient hypothesis, water level