Do the same genus plants have consistent adaptation strategies in cold-wet environments? A case study of leaf suitability of 19 Syringa species

Carbon cost-benefit theory indicates that leaf photosynthesis benefit and structure cost have scaling relationship. However, this relationship has not been tested in the perennial cold-wet regions. Shorter growing seasons in cold-wet climates severely limit plant growth, making it important to explore the light interception and economic strategies for the survival of plants in this region. We measured leaf area (LA), leaf fresh mass (LFM) and leaf dry mass (LDM) of 19 Syringa species around Xi’ning city to explore leaf scaling relationship and adaptation strategies. Our results showed that LA, LFM and LDM varied among species, with the coefficients of variation (CV) among species being 64.61%, 76.43% and 65.94%, respectively. For all species, LDM with LFM and LA showed isometric growth, and only LA and LFM followed allometric growth with a scaling exponent greater than 1 (p < 0.05). Linear correlation indicated that, with the increase of LA, the scaling constant tended diminishingly. Ultimately, according to the CSR (Competitor - Stress tolerator - Ruderal) strategy division, nineteen plants were divided into strategy CS (competitor & stress tolerator) and strategy S/CS (stress tolerator/competitor & stress tolerator). What’s more, LA, LFM and LDM of CS strategy plant were all significantly greater than S/CS strategy. In conclusion, plants in cold-wet habitats tend to have a more conservative economic strategies; and combined with the CSR theory, these plants are more competitive and stress tolerators. More attention should be paid to the effects of harsh environments on plant life history strategies.