Root Distribution In Lijiang Ecotone And Their Relationship To Soil Properties

Studying the relationship between roots and soil is an important way to determine the fundamental reasons for ecological degradation in areas of riverside belt. Concentrating on the problem of ecosystem degradation in the Lijiang River, this paper explored the plant root distribution features of degraded ecosystems on the river-land ecotone. In the repair process, root distribution characteristics are an important basis for the characterization of different herbs’ soil and water protection functions. Thus, there is an urgent need to carry out the study into the types of dominant herbaceous plant root distribution in different sites on the Lijiang River ecotone. This paper studied the root characteristics, such as root length density, specific root length and root biomass in different soil depths, and assessed the correlation between root characteristics and soil organic matter, total nitrogen and available phosphorus. This research was conducted on gentle slope, steep slope, middle bar and artificial bank slope from four typical site types on the river-land ecotone, which aimed to provide a scientific basis for vegetation restoration, vegetation configuration and material selection of fast greening plants during the process of ecological restoration. The result shows:(1)Polygonum hydropiper and Conyza Canadensis grow best on the gentle slope. Steep slope is the most suitable site condition for Sida rhombifolia L and Achyranthes bidentata B1. The middle bar is the most appropriate area for Tatarian Aster and Artemisia argyi. The artificial bank can provide the optimum environment for the growth of Humulus scandens Merr.(2) With the increase of soil depth, the root length density and root biomass decreased in each site type, but the difference between the root length density and root biomass gradually decreased, which indicated that the effects of the terrain surface, types of plant and growth conditions on the distribution of root length density gradually decreases with the increase insoil depth.(3) Pterocarya stenoptera with high total nitrogen content of root length density has1.24times as tall as Geum aleppicum’s,1.87times of Suffrutescent Securinega Twig. The difference in total nitrogen content is significant with the distribution being Pterocarya stenoptera> Geum aleppicum> Suffrutescent Securinega Twig. The content of available phosphorus relationship is Suffrutescent Securinega Twig> Geum aleppicum> Pterocarya stenoptera, and the values separately are11.56g/kg,5.37g/kg,3.99g/kg. Since Lijiang River water has been affected by human activities for a long time, the available phosphorus content in the Suffrutescent Securinega Twig is much greater than that others. Root length density are positively correlated with organic matter and total nitrogen, and negatively correlated with available phosphorus.(4) Root length density, specific root length and root biomass are positively correlated with organic matter and total nitrogen, and negatively correlated with available phosphorus. We can therefore draw the conclusion that with more soil roots, there is more organic matter and total nitrogen, and less available phosphorus. Fine root length and biomass have a significant positive correlation with root length density at0.01level (two tails), and show a negative correlation with root biomass density.