Responses of leaf and root functional traits of dominant species to fencing in a desert steppe

Plant functional traits are core attributes that are closely related to plant growth and survival. By studying the functional traits of dominant species, we can better understand plant survival and growth strategies under fencing conditions. This study examined the variations in plant functional traits and their trade-off mechanisms under three treatments: grazing, 7 years of fencing (FY7), and 15 years of fencing (FY15). The study focused on two key species of the desert grassland, Lespedeza potaninii and Agropyron mongolicum.The results indicated that: 1) The leaf area, leaf nitrogen content, leaf dry matter mass, leaf phosphorus content, specific root length, specific surface area, and root phosphorus content of L. potaninii were significantly higher (P < 0.05) under the grazing (FM) treatment compared to the FY7 and FY15 treatments. Additionally, the leaf area, leaf nitrogen content, specific leaf area, specific root length, specific surface area, root nitrogen content, and root phosphorus content of A. mongolicum increased under fenced conditions. 2) Principal component analysis indicated that A. mongolicum’s resource acquisition strategy shifted from the conservative end of the economic spectrum (characterized by high leaf dry matter mass, high leaf tissue density, high root tissue density, and high root diameter) to the acquisition end of the spectrum (exhibiting high specific leaf area, high specific root length, and high specific surface area) under fenced conditions. Additionally, the economic spectrum observed in the root system of L.potaninii did not align with that of the entire plant. Plant functional traits are closely related to soil factors, with bulk density, total phosphorus, and available phosphorus being the primary soil factors influencing leaf and root functional traits. From a functional trait perspective, fencing affects plant leaf and root functional traits, thereby altering plant resource acquisition strategies.