冬季南亚热带森林演替中后期优势树种幼叶光保护策略

为了解演替中期和后期优势树种对冬季不同光强的适应性,对在全光照(100%自然光强)和低光照(30%自然光强)下生长的演替中期优势种木荷(Schima superba)、锥栗(Castanopsis chinensis)和黧蒴(Castanopsis fissa)及演替后期优势种华润楠(Machilus chinensis)、黄果厚壳桂(Cryptocarya coninna)和厚壳桂(Cryptocarya chinensis)的生理生化响应进行了研究。结果表明,与全光照相比,低光照下演替中期优势树种幼叶的非光化学猝灭(NPQ)、类胡萝卜素与叶绿素的比值(Car/Chl)和花色素苷含量下降,细胞质膜渗透率增加;而演替后期优势树种幼叶的花色素苷含量增加、细胞质膜渗透率降低,且受光抑制的程度低(Fv/Fm高)。此外,除总抗氧化能力外,演替中期优势树种幼叶的花色素苷含量、NPQ和Car/Chl均显著低于演替后期优势种。因此,演替后期优势树种可以通过灵活多样的光保护策略来提高对冬季强光环境的适应能力,而演替中期优势种在光保护策略的多样性及光保护能力上均弱于演替后期优势种。

Photoprotection Strategies in Young Leaves of Dominant Species in Mid- and Late-Successional Stages of Low Subtropical Forest in Winter

In order to understand the mechanism of photoprotection strategies of dominant species at different successional stages under different light environments in winter, the physiological and biochemical responsethree dominant species at mid-successional stage, i.e. Schima superba, Castanopsis chinensis and Castanopsis fissa and three dominant species at late-successional stage, i.e. Machilus chinensis, Cryptocarya coninna, Cryptocarya chinensis grown on full light (100% natural light) and low light (30% natural light) were studied. The results showed that, compared with full light, the non-photochemical quenching (NPQ), ratio of carotenoid to chlorophyll (Car/Chl) and anthocyanin content in young leaves of dominant species at mid-successional stage under low light decreased, and the relative cytoplasmic membrane leakage increased. On the contrary, the anthocyanin content in young leaves of dominant species in the late-successional stage increased, the relative cytoplasmic membrane leakage decreased, and the degree of light inhibition was low (high F_v/F_m). In addition, the anthocyanin content, NPQ and Car/Chl in young leaves of mid-successional species were significantly lower than those of late- successional species except of total antioxidant capacity. So, the dominant species at late-successional stage could improve their adaptability to high light environments in winter through their flexible light protection strategies. However, the diversity of light protection strategies and light protection ability of dominant species at mid- successional stage were weaker than those at late-successional stage.