Effects of water level fluctuations on root architectural and morphological traits of plants in lakeshore areas of three subtropical floodplain lakes in China.

Plant roots in lakeshore areas can directly determine the survival of the aboveground plant parts. However, most current studies are focused on the aerial shoots, and less attention has been paid to the functions of the roots. In order to evaluate the effects of water level fluctuations (WLFs) on root architectural and morphological traits of plants in lakeshore areas, field investigations were conducted seasonally in three subtropical floodplain lakes with different types of WLFs. The results showed that both the pH and moisture contents of the soils were significantly different in all seasons among the three lakes, while the total nitrogen and total phosphorus in the soils only showed significant differences in certain seasons. Significant differences were also found in the two architectural trait parameters (root length density and root branching number) and three morphological trait parameters (root tissue density, root surface area, and root volume), all of which (except for root tissue density) were highest in the Dahuchi lake that experiences intermittent WLFs, and lowest in the Chaohu Lake with reservoir-like WLFs. With increasing lakeshore elevation gradients, we found that root length density, root branching number, root surface area, and root volume in the three lakes changed significantly, and all these root trait parameters increased first and then decreased. However, no significant differences were found for the above four root traits in the three lakes over the different seasons. Spearman correlation analyses indicated that both the hydrological and physicochemical factors were strongly correlated with the architectural and morphological root trait parameters, and the duration of submergence (duration) was the most important factor, judging from the correlation coefficients (R). The results of stepwise multiple regression further indicated the duration was the key factor affecting plant root traits. Based on the results of this study, we suggest that the WLFs in reservoir-like lakes should be changed in order to improve the ecological functions of the lakeshore.