Vegetation restoration in sand dune ecosystems has drawn increasing attention during the past few decades. Wind erosion, sand burial and water stress are the most important abiotic factors in sand dunes.
With higher initial survival rate and competitiveness, vegetative regeneration relies more on buds for plant population regeneration and vegetation restoration in sand dunes. Therefore, the sand dune ecosystem is the ideal place to study the effect of both stress and disturbance on vegetation regeneration. However, how belowground bud bank in sand dune ecosystems respond to severe aeolian activities and water stress has been rarely discussed.
In a study published in Ecological Indicators, Dr. MA Qun and Prof. LIU Zhimin from the Institute of Applied Ecology of the Chinese Academy of Sciences investigated the bud bank pattern under different disturbance and stress in the semi-arid sand dune ecosystem in Inner Mongolia, aiming to determine whether bud type and density can be used as the indicators of disturbance and stress level in sand dunes.
They applied linear mixed effect models (Y= [β0aspect] fixed + [γ type]random) to analyze the effects of dune type, dune position and dune aspect on bud bank density, and linear regression equations (Y=ax+b) to analyze the relationship between soil water content and bud type.
The researchers found that bud density was 86 and 51 bud m-2, higher in the semi-fixed and mobile dunes than in fixed dunes, respectively (40 buds m-2, P<0.05). Root-sprouting buds accounted for a larger proportion of the total number of buds in the windward aspect of the dunes, whereas tiller buds were predominant in the leeward aspect of the dunes. Plants tended to produce more rhizome buds and root collar buds in the lowland.
These results demonstrated that different bud bank types showed different adaptive strategies to disturbance and stress. Root-sprouting buds are stress tolerance-ruderal strategist, whereas tiller buds were ruderal strategists. Rhizome buds are competitive strategists. They also demonstrated that plants from habitats with intermediate disturbance and stress levels produce more buds than in other habitats.
This study will help to explore plant strategies in other biogeographic regions, and test the generalization by Grime of two key factors broadly categorized as stress and disturbance limiting plant biomass, as the basis for his classification of plant survival strategies.
