Soil-Binding Capacity Of Riparian Plants In Three Gorges Reservoir Region

How to reduce and prevent the soil and water loss is an important issue in the eco-environmental construction of Three Gorges Reservoir Region. This paper aimed at the two main reasons of soil and water loss that Three Gorges Reservoir Region suffered from, stream scouring and immersing erosion, studied the soil-binding capacity of riparian plants from both soil anti-scouribility and anti-erodibility aspects. Soil anti-scouribility means the capacity that soil resists the mechanical damage and downward movement promotion of the runoff;and soil anti-erodibility is the capacity of soil to resist the erosion power.Potted plants in ecological garden plot were used in this experiment, and the seedlings were got from the riparian of Jialing River. The planting period was from mid-May to early August 2005. During the experiment, each plant's enhancement effects on soil anti-scouribility and anti-erodibility were determined, as well as the root biomass, then root morphological indices were quantified using WinRHIZO root analysis system.Several plant species from riparian zones in Three Gorges Reservoir Region were selected and their enhancement effects on soil anti-scouribility were determined. The results showed that: 1) Diffuse-rooted and tap-rooted plants both had large enhancement effects on soil anti-scouribility and the enhancement effects varied in different species. 2) There was no significant difference between diffuse-rooted plants and tap-rooted plants in the whole enhancement effects on soil anti-scouribility, and the effect per root biomass of diffuse-rooted plants was much larger than that of tap-rooted plants. Based on the results, it is clear that some species are appropriate in enhancing soil anti-scouribility, such as Erigeron annum (L.) Pers., Eleusine indica (L.) Gaertn., Cyperus rotundusL., Hemarthria compressa (L.f.) , Artemisia annua L., Carpesium abrotanoides L., Aster subulatus Michx., etal.Several plant species from riparian zones in Three Gorges Reservoir Region were selected and their enhancement effects on soil anti-erodibility were determined. The results showed that: 1) Diffuse-rooted and tap-rooted plants both had large enhancement effects on soil anti-erodibility, and the enhancement effects varied in different species. 2) The enhancement effects on soil anti-erodibility of diffuse-rooted plants were much larger than that of tap-rooted plants. Based on the results, it is clear that some species are appropriate in enhancing soil anti-erodibility, such as Lactuca indica L., Achyranthes bidentata Bl., Phragmites communis Trin., Arundinella hirta, Erigeron annum (L.) Pers., Cyperus rotundus L., Oplismenus compositus (L.) Beauv., Digitaria sanguinalis (L.) Scop., etal.The effects of root biomass and morphology characters on soil anti-scouribility were studied. The main results showed that: 1) The enhancement effect on soil anti-scouribility was correlated with root characters such as root biomass, total root length and root surface area. 2) The enhancement effects varied in different root diameter classes, and roots in the d^O. 5mm class had the largest effect. With the increasing of the root diameter class, the effect of the root to soil anti-scouribilty became smaller. 3) There was no significant correlation between soil anti-scouribility and tap root biomass, while linear correlation between soil anti-scouribility and diffuse root biomass. 4) The relationships between soil anti-scouribility and root morphology characters were regressed using the quadratic equations. According to the results, it is suggested that choosing surface area of total root or root in ^ lmm diameter class in order to estimate the enhancement effect of root system.The effects of root biomass and morphology characters on soil anti-erodibility were studied. The main results showed that: 1) The enhancement effects on soil anti-erodibility varied in different root diameter classes, and roots in the d^O. 5mm class had the largest effect. With the increasing of the root diameter class, the effect of the root to soil anti-erodibility became smaller. 2) There was no significant correlation between soil anti-erodibility and tap root biomass, while weak correlation between soil anti-erodibility and diffuse root biomass. So, neither tap-rooted nor diffuse-rootedplants could use root biomass to estimate its enhancement effect on soil anti-erodibility. 3) There were significant correlations between soil anti-erodibility and root morphology characters of tap root and diffuse root either, and the relationships were regressed using the logarithmic equations. It is obvious that the enhancement effect on soil anti-erodibility was correlated with root morphology characters. According to the results, it is suggested that using total root surface area to estimate its enhancement effect.In general, this paper: 1) studied the soil-binding capacity of riparian plants in Three Gorges Reservoir Region by soil anti-scouribility and anti-erodibility experiments, and there were few reports on this study at present 2) determined the soil-binding capacity of more than SO plant species and made the compare study, which was scarcely ever reported before. Moreover, some species which had high binding capacity were put forward to the range of plants that may used to prevent the soil and water loss. 3) determined the differences between tap root and diffuse root of their enhancement effects on soil anti-scouribility and anti-erodibility. 4) discussed the effects of root biomass, root morphology characters on soil anti-scouribility and anti-erodibility, made clear the relationships between root binding capacity and root characters.