Leaf traits and leaf economic spectrum of Kandelia obovata at different ages in Minjiang River Estuary

In order to clarify the characteristics of leaf traits and leaf economic spectrum of Mendelian ovation in young and mature forests, the leaves of 5-year-old and 15-year-old K.ovation forests in Minjiang River estuary wetland of Fuzhou City were studied. By measuring 30 indexes of leaf morphological traits, leaf chemical characteristics, leaf stomachs traits, leaf vein characteristics and photosynthetic characteristics, the differences of leaf traits between 5-year-old and 15-year-old K. obovata were compared, and the leaf economic spectrum of different ages of K. obovata was constructed. The results showed that in terms of leaf morphology and chemical characteristics, leaf thickness and leaf carbon content of K. obovata in 5-year-old were significantly higher than those in 15-year-old, while leaf area was the opposite. In terms of stomatal and leaf vein characteristics, the 10 structural characteristics of leaf thickness, leaf stomatal width, stomatal area, stomatal perimeter, stomatal opening length, stomatal opening width, stomatal opening area, stomatal opening perimeter, stomatal density, veinlet density in 5-year-old were significantly higher than those in 15-year-old. In terms of photosynthetic characteristics, the three photosynthetic characteristics of stomatal conductance, water use rate, carboxylation rate in 5-year-old were significantly higher than those in 15-year-old, while intercellular CO₂ concentration was opposite. In summary, there were significant differences in leaf traits between 5-year-old and 15-year-old K. obovata, showing different plant survival strategies. Among them, The leaf economic spectrum of K. obovata in 5-year-old showed thicker leaf thickness, higher leaf phosphorus content, larger stomatal density, larger stomatal opening, higher veinlet density, stronger photosynthetic capacity and lower specific leaf area, leaf nitrogen content and other positive leaf activities, showing stronger growth vigor and photosynthetic efficiency, which was the leaf economic spectrum model of 'rapid investment-income type'. The economic spectrum of K. obovata leaves in 15-year-old showed thin leaf thickness, low leaf phosphorus content, small stomatal density, small stomatal opening, low vein density, weak photosynthetic capacity and high specific leaf area, leaf nitrogen content and other characteristics, showing a more simplified morphological structure and reducing its chemical activity, thereby improving the long-term survival ability in unfavorable habitats, which was a 'slow investment-income' leaf economic spectrum model.