Clonal growth forms differ in trait-mediated productivity responses to long-term nitrogen and water addition in a temperate steppe - Jun Sheng; Meng Zhou; Yumeng Guo; Fengfeng Cao; Yujia Yuan; Guangyuan Yuan; Zuoqing Jiang; Wen-Hao Zhang; Wenming Bai (Plant and Soil, 2026)