Font Size: a A A

The Effects Of Summer And Winter Long-term Submergence On Survival, Underwater Growth And Recovery Growth Of Several Terrestrial Plants

Posted on:2009-11-19Degree:MasterType:Thesis
Country:ChinaCandidate:H F WangFull Text:PDF
GTID:2120360242997175Subject:Ecology
Abstract/Summary:PDF Full Text Request
Owing to the construction of Three Gorges reservoir, some riparian areas along the river bank will be submerged as long as 180 days. In order to control soil erosion and maintain the eco-environmental quality in the water-level-fluctuation-zone in Three Gorges reservoir region, riparian vegetating is an important measure among all possibilities. For riparian vegetating, selection of appropriate plant species adapted to long-term submergence is crucial.Submergence leads to shortage of oxygen and inhabitation of photosynthesis of plant, as a result, the biomass of plant decreased significantly, the survival, underwater growth and recovery growth of plant were affected adversely by long-term submergence. To cope with submergence, different plants exploit various tactics by adaptation on physiological, anatomical and morphological levels.We select these seven plant species: Ficus tikoua, Triarrhena sacchariflora, Hemarthria altissima, Cynodon dactylon, Acorus calamus, Vetiveria zizanioides and Alternanthera philoxeroides. Aim to reveal whether these plants would be suitable plant for revegetation of water-level-fluctuation zone in Three Gorges reservoir region, flooding simulation experiment was conducted and the growth, survival and recovery growth of these species subjected to 30d, 60d, 90d, 120d, 150d, and 180d full submergence(all plants submerged in a 2.5m poll) in summer and winter were investigated.Survival and growth response of Vetiveria zizanioides, Acorus calamus and Alternanthera philoxeroides to long-term submergence(1) The three plant species showed high tolerance to full submergence, 87.5%, 100% and 50% of all submerged plants of V. zizanioides, A. calamus and A. philoxeroides after 180d submergence survived, respectively. (2) These three plant species possessed different underwater growth ability. V. zizanioides grew slowly, the length and number of total leaves did not change significantly. A. calamus kept producing narrower and longer leaf blades as compared with those of control plants. A. philoxeroides grew vigorously, shoots elongated notably and new leaves formed quickly in less than 30d, however, the length of total shoots and the number of total leaves did not increase significantly after any longer duration. (3) Submergence inhibited the biomass accumulation of three plant species significantly, but the change of aboveground biomass and belowground biomass differed among the three plant species. The aboveground biomass and belowground biomass of V. zizanioides did not change significantly during its submergence duration, but the root/shoot ratio was slightly higher than that of control plants. The aboveground biomass of submerged A. calamus plants decreased with the duration of submergence, but it was higher than that of control plants, the belowground biomass of A. calamus decreased significantly with the duration of submergence, and their root/shoot ratio was lower than that of control plants. The aboveground biomass of A. philoxeroides did not change significantly when it was submerged in water, but the belowground biomass decreased greatly with the duration of submergence, and the root/shoot ratio was lower than that of control plants. The results demonstrated that these three plant species were submergence-tolerant and could be applied in riparian vegetating of water-level-fluctuation zone in Three Gorges reservoir. Meanwhile, our results also suggested that the survival and thus tolerance of these three species to submergence was associated with their performance of underwater growth. Intensive underwater growth may have consumed more nutrient storage and decreased the availability of energy for maintenance, which is crucial for survival. Limited underwater growth ability and sufficient carbohydrate reserve may be important factors for selecting long-term submergence-tolerant species.The effects of long-term submergence on survival and recovery growth of four riparian plant species in Three Gorges reservoir region(1) Survival of these four plant species after long-term submergence was associated with their distribution pattern on riverbanks. F. tikoua, mainly occurring on "high-elevation site", died after 30d submergence. T. sacchariflora, originating from "mediate-elevation site", died after 150d and 180d submergence. 90% and 100% of all submerged plants of H. altissima and C. dactylon, originating from "low-elevation site", survived 180d submergence, respectively. (2) Submergence inhibited the growth of all plants, and the total biomass of each species was significantly lower than that of control plants. The aboveground biomass of all submerged plants decreased significantly. After 60d and 120d submergence, the belowground biomass of T. sacchariflora decreased significantly, but that of H. altissima and C. dactylon did not change significantly during its submergence duration. (3) All survived plants after de-submergence could start to regrow. After 30d, 60d and 90d submergence, the RGR in total shoots length of all submerged plants has no significant difference with those of control plants, but after 120d, 150d and 180d submergence, the RGR in total shoots length of submerged H. altissima and C. dactylon were higher than those of control plants. The RGR in total leaves number was always higher than that of control plants after all submergence durations. After long-term submergence, the plants were under low-nutrient condition, it might be the effective way for the plants to generate more new leaves to accelerate the photosynthesis.The effects of long-term winter submergence on survival, underwater growth and recovery growth of Ficus tikoua, Triarrhena sacchariflora, Hemarthria altissima, Cynodon dactylon, Acorus calamus and Alternanthera philoxeroides(1) F. tikoua died after 30d submergence, 62.5%,100%,100%,100% and 100% of all submerged plants of T. sacchariflora, H. altissima, C. dactylon, A. calamus and A. philoxeroides after 180d submergence survived, respectively. (2) Submergence inhibited the aboveground growth and the biomass accumulation. The A. calamus and A. philoxeroides could keep producing new leaves and shoots, but the belowground biomass of these two plant species decreased significantly. (3) All survived T. sacchariflora, H. altissima, C. dactylon, A. calamus and A. philoxeroides could start to regrow quickly after submergence, the RGR of submerged plants has no significant difference with that of control plants, the RGR in total leaf number of T. sacchariflora and A. philoxeroides were higher than that of control plants. The results indicated that: In winter, F. tikoua died after 30d submergence, T. sacchariflora, H. altissima, C. dactylon, A. calamus and A. philoxeroides had high survival and good recovery growth after long-term flooding, and it showed good tolerance to flooding and could be applied in revegetation of water-level-fluctuation zone in Three Gorges reservoir region.In general, except F. tikoua, all the other plants are submergence-tolerant species, although employing different tactics to cope with submergence, and these plants perform better in winter submergence than in summer submergence, these plants could be applied in riparian revegetation in Three Gorges reservoir region.
Keywords/Search Tags:Three Gorges reservoir region, long-term submergence, survival, recovery growth
PDF Full Text Request
Related items