Rock outcrops affect adjacent soils and vegetation at fine scales in karst areas

Rock outcrops (ROCs), occurring as exposed rock or isolated blocks, are common structures associated with land plots and plant communities in terrestrial ecosystems, especially in karst-dominated landscapes. They have various effects on the karst plant matrix through the export of water and nutrients from runoff.

In a study published in CATENAresearchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences suggested that karst ROCs significantly affect the physical and chemical parameters of the soil and adjacent plant biomass at fine scales, and these effects are correlated with the size parameters associated with ROCs, such as coverage area.

The researchers randomly selected 30 isolated ROCs from semi-moist karst grasslands in southwestern China and collected rainwater (from rainfall) and ROC runoff for chemical analysis. They then determined the soil parameters and above-ground and below-ground plant biomass (AGB and BGB, respectively) of plants at intervals of 0-30, 31-60, 61-90, 91-190 and 191-290 cm, adjacent to the ROC rock-soil interface.

They found that some of the soil physical and chemical parameters were higher in the 0-30 cm sample plots than those in the other plots further away from the ROC. The plant AGB and BGB were higher in the 0-30 cm and 31-60 cm plots and correlated with the size parameters of ROCs.

The results imply that ROCs affected adjacent soils and plant growth within a certain range of the karst-rock-soil interface.

“Our findings provide a foundation for understanding the complexity of planting matrices and provide clues to seedling planting strategies used in restoration practices,” said XTBG’s Shen Youxin.