Study On The Ecological Response Of The Leaf Characteristics Of The Minimum Population Magnolia Sinensis To Different Altitudes

This research,mainly focused on the extremely Minimum population of planted leaves of Magnolia sinensis,naturally scattered in Dachuan Town,Lushan County,Ya’an City.Based on the comprehensive survey of Magnolia sinensis’ s distribution scope,we set up five altitude gradients: 1873 m,2063m,2160 m,2265m,and 2372 m,measured and analyzed 24 indicators of leaf anatomical structure,leaf pigments,and antioxidant system in Magnolia sinensis at different altitude gradients.Then,we summarized the characteristics of the changes in various indicators of the leaves of Magnolia sinensis with elevation gradients.Then,we analysed the correlations among the indicators and the correlations between the indices and elevations.We also explored the characteristics of the leaves of Magnolia sinensis in adapting to different elevations.The results were shown as follows:1.With the increase of the altitude,the density of stomata in the lower epidermis of leaves of Magnolia sinensis was smaller,the area of stomatal apparatus was increased,the lower epidermis gross density was decreased,the upper and lower epidermis thickness of the leaves increased,the palisade tissue and spongy tissue thickness decreased,and the total leaf thickness decreased.The co-evolving structure of each anatomical structure was most used to construct the structure and function of the leaf,so as to respond to changes in the environmental factors such as radiation,CO2 partial pressure,moisture,and air flow on the elevation gradient.2.With the increase of the altitude,the content of chlorophyll(chlorophyll a + chlorophyll b)and carotenoids in leaves of Magnolia sinensis increased,and the values of chlorophyll a/b and carotenoid/chlorophyll changed little,and the anthocyanin content decreased.There was a synergistic or reverse change between the content of the pigments,which shows the characteristics of the diurnal temperature difference in response to the elevation gradient and the strong UV-B radiation,and make full use of the light energy and the protection of the light reaction system.3.With the increase of altitude,the content of superoxide dismutase(MDA)and proline(Pro)in the leaves of Magnolia sinensis leaves increased,and the total activity of superoxide dismutase(SOD)decreased.Peroxidase(POD)),catalase(CAT),ascorbate peroxidase(APX)activity,and ascorbic acid(As A)content increased first and then decreased.The anti-oxidation system participates in the scavenging process of reactive oxygen radicals through complex and diverse synergy or complementation,which reflects the response laws of temperature and radiation changes on the elevation gradient.4.In the range of Magnolia sinensis’ s distribution elevation(elevation,1873-2372 m),the leaf anatomical structure,leaf pigments,and antioxidant system indices were within the threshold with the temperature,light,radiation,moisture,and other environmental factors on the elevation gradient,as well as the harmonization of the structure and function of this three sides.The complex regulation mechanism formed by the leaves of Magnolia sinensis in the long-term adaptation to different altitudes reflects the response characteristics of individuals and populations of Magnolia sinensis to altitude gradients.