Abstract: The karst faulted basin is among the areas most severely affected by rocky desertification. To understand root response characteristics and adaptation strategies of dominant shrub species to rocky desertification in karst faulted basins, we selected Dodonaea viscosa, Osyris wightiana, and Osteomeles schwerinae with relatively similar growing status across different degrees of rocky desertification (none, potential, mild, moderate, and severe) in Jianshui County, Yunnan Province. By excavating soil profiles to obtain root and performing root scanning, we analyzed changes in root functional traits of these dominant shrubs. The specific root length, root tissue density, and specific root area of Dodonaea viscosa increased with the intensification of rocky desertification. Root tissue density, specific root length, specific root area, and branching intensity of Osyris wightiana increased initially and then decreased from none to moderate rocky desertification, and then significantly increased and reached their maximum values in severe rocky desertification, respectively increasing by 2.6, 2.8, 15.0, and 0.3 times compared to the moderate rocky desertification (P<0.05). Root tissue density, root area density, and root length density of Osteomeles schwerinae decreased with the increasing degree of rocky desertification, while branching intensity significantly increased in moderate and severe rocky desertification, with respective increases of 121.2% and 117.6% compared to the non-rocky desertification (P<0.01). Root tissue density, specific root length, and specific root area of Osyris wightiana were significantly higher in severe rocky desertification than Dodonaea viscosa and Osteomeles schwerinae (P<0.05). Root tissue density, specific root length, and specific root area of dominant shrub species were significantly positively correlated with soil available potassium concentration (P<0.01), while root area density and root length density were significantly positively correlated with plant height and aboveground biomass (P<0.05). Those results suggested that the roots of dominant shrub species exhibited a certain level of responsiveness and different adaptation strategies to varying degrees of rocky desertification. Soil available potassium content was one of the main factors influencing their adaptation to rocky desertification, while the aboveground parts played a role in regulating root traits. The results can provide a theoretical basis for optimizing vegetation restoration methods for rocky desertification in karst faulted basins.

Key words: rocky desertification, stress, shrub, root trait, ecological adaptation