Variations in root biomass, spatial distribution, and adaptation characteristics of Prunus sibirica with diameter class and soil depth

Abstract

Prunus sibirica is a pioneer species for establishing soil-water conservation forests. The study investigated root growth and development in P. sibirica plantation forests to reveal the nutrient flow and material cycling rules during the growth process. Using four diameter classes, total excavation was employed to quantify root biomass and spatial distribution, while anatomical structure and physiological indices were measured to assess adaptation features. Significant differences (P < 0.05) were found in the spatial biomass distribution, anatomical structure, antioxidant enzyme activity, and osmotic adjustment among the different diameter classes of P. sibirica roots. Root biomass increased with diameter class. Significant positive correlations were identified among tree height, basal diameter, and total root biomass. Three-dimensional mapping of coarse root distribution revealed that as diameter class increased, the horizontal distribution range gradually expanded and vertical penetration deepened, exhibiting pronounced spatial asymmetry. Anatomical analysis showed that within the same diameter class, xylem diameter, phloem thickness, periderm thickness, and vascular cambium thickness all increased with root diameter. The large-diameter class of P. sibirica root systems had high levels of antioxidant enzymes and osmoregulatory substances. Root antioxidant enzyme activity, osmoregulatory substance concentration, and membrane stability decreased with increasing soil depth, while root vigor increased. These results suggest the large-diameter class of P. sibirica root systems has a high root absorption capacity and can accumulate more organic matter, making them more resilient to adverse conditions.