Succession of a broad-leaved Korean pine mixed forest: Functional plant trait composition

A longstanding goal of ecology and conservation biology is to understand the climatic and biological controls of forest succession. However, the patterns and mechanisms that guide forest succession, especially within broad-leaved forests, remain unclear. We collected leaf traits and abiotic data across a 200-year chronosequence within a broad-leaved Korean pine forest in northeastern China. We focused on five key leaf traits related to resource acquisition and competition by quantifying the community-weighted trait distributions for specific leaf area (SLA), leaf dry matter concentration (LDMC), leaf nitrogen content (Nₘₐₛₛ (g/kg)), leaf phosphorus content (Pₘₐₛₛ (g/kg)) and the ratio of nitrogen content to phosphorus content (Nₘₐₛₛ/Pₘₐₛₛ). We also studied how these traits respond to changing environmental variables (climatic, soil and topographical) during succession. Redundancy analysis was used to examine the importance of the environmental variables in shaping the successional variation in plant traits. Our results revealed the following. Older forests differed significantly from younger forests in species composition and trait distribution. For example, SLA, leaf N and P content and the N/P ratio tended to increase and then decrease throughout the community during forest succession (p < 0.01). LDMC was also reduced over the course of succession. Mean annual temperature (MAT) and mean annual precipitation (MAP) correlated significantly with the succession of SLA and LDMC. However, temperature and rainfall were not significantly related to the temporal pattern of leaf nutrient (N and P) contents. The successional variation in leaf nutrients was instead mainly affected by soil and terrain factors (slope). Climatic factors independently accounted for 21.5% of the latitudinal difference in leaf function, which was slightly higher than soil factors (13.2%) and topographical factors (8.7%).