Responses of the root architecture of Stipa grandis to grassland degradation

The study was conducted to investigate responses of root architecture of Stipa grandis grown under different grassland degradation levels (light, medium, high and extreme) in Xilin Gol League. The relative completed roots of S. grandis were collected by trenching and analyzed by using the root analysis system of WinRHIZO to determine total root length, root surface area, total root volume, root average diameter, number of root tips, number of furcation and average branching angle, number and length of first vertical root, number and length of first lateral root, number and length of secondary lateral root, number of adventitious root. The data obtained was analyzed by oneway ANOVA and principal component analysis. The results indicated that 1) the number of furcation, the surface area of root and the total length of root were the preferred indexes for analyzing S. grandis variation to grassland degradation, while the number of furcation had the strongest explanation strength of the indexes to the variation. The cumulative contribution rate of the three root architecture indexes was 90.7%. 2) With the degradation development from light to extreme, the root architecture of S.grandis was obviously miniaturized. This phenomenon was especially obvious in medium degradation grassland. 3) The miniaturized root architecture of S. grandis eventually led to miniaturization of the entire plant, so the role of S. grandis as constructive species in the succession process of the community degradation was gradually weakened and finally replaced by other dominant species.