Marginal response of non-structural carbohydrates and increased biomass in a dominant shrub (Dasiphora fruticosa) to water table decline in a minerotrophic peatland.

Abstract

Assessing how dominant peatland species, such as Dasiphora fruticosa, adapt to water table decline is crucial to advance understanding of their growth and survival strategies. Currently, most studies have primarily focused on their growth and biomass, with limited knowledge on the response of non-structural carbohydrates (NSCs) and physiological adaptations of these woody plants under long-term drainage. This study assessed the response of photosynthesis and transpiration rates, biomass, and NSC concentrations (including soluble sugars and starch) in the leaves, stems, and roots of D. fruticosa to long-term drainage in a minerotrophic peatland. The aim was to elucidate the plant response and adaptation mechanisms to water table decline. Dasiphora fruticosa effectively regulated carbon (C) demand and supply by significantly enhancing photosynthesis, transpiration, and biomass accumulation, thereby maintaining stable C storage as the water table declined. There was a notable reduction in soluble sugar concentration in leaves with increasing water table decline, while starch concentrations in all three organs remained relatively constant. Although the concentration of soluble sugars in leaves was consistently higher than that in roots and stems, the relative proportion of soluble sugars and starch gradually decreased in leaves and increased in roots and stems with water table decline. Our findings reveal that D. fruticosa reduces NSC concentrations in leaves while increasing biomass to adapt to water table decline. This acclimation might significantly impact C dynamics in peatlands. Understanding these mechanisms is vital for predicting the dynamics of C sequestration and emission in peatland ecosystems under changing environmental conditions.