关键词: 叶功能性状, 生活型, 叶经济谱, 权衡策略, 木本植物

Abstract:

Objective: This study aims to explore the leaf functional traits and their combinations among woody plants of different life forms in the mountainous region of northeastern Beijing, and systematically analyse the ecological strategy differences of dominant woody plants, providing reference for elucidating the environmental adaptation mechanisms of different life forms in this region. Method: Twenty dominant woody plant species were selected from 19 typical woody plant communities in the mountainous region of northeastern Beijing. A combination of field surveys and laboratory-based physicochemical analyses was used to systematically investigate the 12 typical leaf functional traits and their relationships in three life form types of woody plants—shrubs, deciduous broad-leaved trees and coniferous trees to reveal the trade-off strategies of those woody plants. Result: 1) The leaf area (LA), specific leaf area (SLA), leaf nitrogen content (LNC) and leaf phosphorus content (LPC) of coniferous trees were significantly lower than those of deciduous broad-leaved trees and shrubs, while the leaf thickness (LT), leaf carbon content (LCC), carbon-to-nitrogen ratio (C∶N) and carbon-to-phosphorus ratio (C∶P) of coniferous trees were significantly higher than those of deciduous broad-leaved trees and shrubs, implying that the deciduous trees had higher construction costs and higher nitrogen and phosphorus utilization efficiency in their leaves. 2) The SLA of all dominant woody plants was negatively correlated with leaf dry matter content (LDMC), while LNC was positively correlated with LPC, indicating a trade-off between investment in leaf photosynthetic capacity and physical defense structure. Nitrogen and phosphorus elements in leaves synergistically promoted plant growth, and the demands for nitrogen and phosphorus elements among woody plants in similar habitats did not exhibit specific variations with life forms. 3) There was significantly positive correlation between LT and LDMC in deciduous broad-leaved trees, there was a significant negative correlation between LT and LDMC in coniferous trees, and there was no correlation in shrubs. This variation can be attributed to the fact that the thicker leaves of deciduous broad-leaved trees require a greater LDMC in order to provide the physical structural support. In contrast, coniferous tree leaves, despite their considerable thickness, were characterized by a lower nutrient content and a reduced degree of stomatal opening and water evaporation, which resulted in a lower LDMC. 4) Principal component analysis and permutational multivariate analysis of variance revealed highly significant differences (P<0.01) among woody plants of different life forms along both chemical and structural trait axes, with an explaining power of 63.84% for the first two axes. The results showed that shrubs tended to have high LNC, LPC and low LCC trait combinations, coniferous trees showed low LNC, LPC and high LCC trait combinations, while deciduous broad-leaved trees varied along the directions of larger LA, LDMC and smaller LT. Conclusion: There are significant differences in some leaf functional traits among woody plants with different life forms. The shrubs and deciduous broad-leaved trees tend to adopt a “fast investment-return” strategy, while coniferous trees adopt a “slow investment-return” strategy. This study provides essential data for understanding plant resource acquisition-adaptation strategies, and biodiversity conservation in the region.

Key words: leaf functional trait, life form, leaf economic spectrum, ecological strategy, woody plant