Leaf Traits To Adaptat To Environmental Changes In North China

Leaves have different traits,such as differentiated leaf morphology,stomatal traits and vein density,which are the result of long-term adaptation to different environments.At present,the leaf morphology,stomatal and vein variation patterns and their characteristics of different species and the same species have been widely reported at regional scale.However,in northern China,the correlation among leaf morphology traits,stomatal traits and vein traits based on environmental factors remains to be understood.In this paper,215 plant leaves distributed along the northern latitude of 40^o were used as materials to analyze the relationship between leaf morphological traits,stomatal traits and minor vein density,and the adaptability to environmental factors.The main results are as follows:1.The variation ranges of leaf area and specific leaf area of plants in northern China are 0.1-69.7 cm^-2 and 19.1-542.3 mg g^-1,respectively.The average values are 4.2cm-2 and 124.4 mg g-1,and the coefficients of variation are 2.3 and 0.8,respectively.Leaf area and specific leaf area increased linearly with the increase of precipitation,but did not respond to temperature.It was considered that precipitation was the key factor to determine the morphological characteristics of plant leaves.2.The variation ranges of stomatal length,stomatal density,abaxial ratio and stomatal index were 5.3-54.9 um,16.2-677.3 mm^-2,22.1-76.7%and 3.4-29.7%respectively,with the average values of 16.1 um,278.6 mm^-2,14.6 mm^-22 and 49.4%,and the coefficients of variation were 0.4,0.6,0.2 and 0.4,respectively.With the increase of precipitation,both stomatal density and stomatal index decrease linearly,while stomatal length and abaxial ratio increase linearly.With the increase of temperature,stomatal density and stomatal index decrease linearly,but stomatal length increases linearly.It is considered that both precipitation and temperature affect leaf stomatal traits.3.Of 215 species,74%are stomatal amphistomatous plants,26%are stomatal hypostomatous plants.However,there are no significant differences in stomatal density,stomatal index,stomatal length and abaxial ratio between amphistomatous plants and hypostomatous plants.4.The variation range of leaf minor vein density in northern China is 1.5-28.5 mm^-2,with an average value of 11.0 mm^-2 and a coefficient of variation of 0.4.Minor vein density decreases linearly with the increase of precipitation and temperature.It is considered that both precipitation and temperature affect the characteristics of plant veins.5.The correlation analysis between leaf traits showed that tomatal density and vein density decreased with the increase of specific leaf area?P<0.001?.With the increase of leaf area,stomatal density,stomatal index and vein density decreased?P<0.001?,and stomatal length and abaxial ratio increased?P<0.001?.Stomatal density was positively correlated with vein density?P<0.001?and negatively correlated with stomatal length?P<0.001?.It is concluded that there are covariant relationships among leaf morphological traits,stomatal traits and leaf vein traits,which together determine the adaptability of plants to different habitats.