Variation in Functional Traits of Woody Plants Across Successional Stages in Subtropical Forests

• Published in: Forests Vol. 16; no. 5; p. 868
• Main Authors: Sun, Cheng, Yao, Jie, Huang, Yongtao, Zang, Runguo
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 21.05.2025
• Subjects: Age; Biodiversity; China; Coniferous forests; Constraints; Deciduous forests; Deciduous trees; Dry matter; Ecosystem stability; Flowers & plants; Forest communities; Forests; Leaf area; Leaves; Mixed forests; Nature reserves; Old growth forests; Plant communities; Restoration strategies; Species composition; Tropical forests; Variation; Vegetation; Woody plants; China; Hubei China
• ISSN: 1999-4907; 1999-4907
• DOI: 10.3390/f16050868

Variation patterns in plant functional traits and their interrelationships play a crucial role in understanding species coexistence mechanisms and ecological differentiation within local plant communities. However, the dynamic patterns of plant functional traits across different forest successional stages remain insufficiently understood. Here, we investigated the woody species composition of subtropical evergreen–deciduous broadleaved mixed forest across 75 plots, representing three successional stages (20-year-old secondary forest, 35-year-old secondary forest, and old-growth forest (>80 years)), in Xingdoushan and Mulinzi National Nature Reserves, Hubei Province, Central China. We measured four functional traits of woody plants: leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), and wood density (WD). For each different age plant community, we calculated (1) species abundance-weighted mean community trait values, and (2) species-level mean trait values. We applied trait gradient analysis to partition and assess correlations of four functional traits across communities of different successional stages, separating within-community (α components) and between-community (β components) variation. To quantify the extent to which environmental constraints influence trait expression, we used the ecological constraint index (Ci). The results revealed significant variation in the four functional traits across communities at different successional stages. Community-level mean LA and SLA decreased significantly with age, WD increased significantly with age, and there was no significant relationship between LDMC and age. The α trait components consistently varied more widely than β components at different successional stages, indicating that biological competition dominates the assembly of local forest communities across various successional stages. Correlations between the four functional traits were dynamically adjusted with the study scale (community-level and species-level) and forest age. The ecological constraints on the four functional traits varied significantly across forest successional stages, with SLA being subject to the strongest constraints. Our findings reveal that biotic competition predominantly shapes community assembly during the succession of subtropical evergreen–deciduous broadleaved mixed forests, while stronger ecological filtering in old-growth stands underscores their role in maintaining ecosystem stability. These insights support more effective conservation and restoration strategies.