漓江水陆交错带典型立地根系分布与土壤性质的关系

研究根系与土壤关系是发掘河岸带生态退化等问题内在原因的重要途径。在漓江流域水陆交错带选取缓坡、陡坡、江心洲、人工岸坡4种典型立地类型,对不同土层深度的根长密度、根系生物量、比根长,以及根系特征与土壤有机质、全氮、有效磷的关系进行了研究,旨在为漓江流域生态修复过程中植被恢复、植被配置、快速绿化材料选取提供科学依据。结果表明:(1)同一立地类型0—10 cm土层和10—20 cm土层比根长差异性不显著。0—10 cm到10—20 cm土层,各立地类型根长密度和根系生物量密度均减小,但不同立地类型根长密度和根系生物量密度的差异程度逐渐缩小,表明地形、地表植物类型及生长状况对根长密度分布的影响也随土层深度的增加而逐渐减小。细根根长和生物量随着土壤深度的增加而减小。(2)土壤有机质含量差异性显著,分布规律为人工岸坡陡坡江心洲缓坡;土壤全氮含量从大到小依次是人工岸坡、陡坡、缓坡、江心洲,其值分别为:3.12、2.33、1.56、1.32 g/kg;土壤全氮与土壤有机质呈显著正相关。江心洲和缓坡有效磷含量远远大于人工岸坡和陡坡,原因是漓江水长期受人为洗漱影响,导致受江水干扰大的立地类型有效磷含量高。(3)根长密度、比根长、根系生物量与有机质、全氮含量呈正相关,与有效磷含量呈负相关,说明土壤根系越丰富,越有利于增加土壤有机质和全氮含量,但遏制了土壤有效磷。细根长度、生物量与根长密度在0.01水平(双侧)上显著正相关,与根系生物量密度呈负相关。

Root distribution in typical sites of 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: Within each site type, the difference between specific root length in the 0-10 cm and 10-20 cm soil layer is not significant. From the 0-10 cm to 10-20 cm soil layer, 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 decr eases with the increase insoil depth. The fine root and root biomass also decrease with the increase in soil depth. The difference in soil organic matter content is significant with the distribution being bank slope > steep slope > middle bar > gentle slope. The total nitrogen content relationship is bank slope > steep slope > gentle slope > middle bar, and the values separately are 3.12 g/kg, 2.33 g/kg, 1.56 g/kg and 1.32 g/kg, respectively. Soil total nitrogen and soil organic matter show a significant positive correlation. Since Lijiang River water has been affected by human activities for a long time, the available phosphorus content in the middle bar and gentle slope is much greater than that in the bank slope and steep slope. 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 at 0.01 level (two tails), and show a negative correlation with root biomass density.