Study On The Physiological Plasticity Of Pioneer Plant Leymus Mollis Grown In Coast Resistance To Wind And Salt

The sea wind, tides, sea erosion affected on the coastal long-term, which resulted in not only the coastal sandy terrain uneven that made the windward and leeward slopes of the shore sand dune, but also made different environment in the coastal dunes（environmental heterogeneity）. It means that windward closed to high tide line, had higher salt content in the soil and wind speed, but on leeward slopes of sand dune of the shore far away from high tide had lower salt content and wind speed. However,Leymusmollis established a single population on windward and coexistenced on the leeward. But it is not known what the physiological plasticity regulation mechanism of Leymusmollis used to adapt heterogeneous environment.This research revealed the physiological mechanism of wind resistance and salt adaptation of Leymusmollis, enrich the anti-sandstorm theory, provide a theoretical basis of the introduction of ecological restoration of coastal plants by analyzed the role of salt influenced the environments heterogeneous 、the sea wind wind influenced the photosynthetic characteristics of Leymusmollis in the windward and leeward side 、the role of the contents of carbohydrate in various organs of leymus mollis in winter and spring with the different temperature changed on the wind resistance. The resultes obtained was as follows:（1）The relationship between soil salt and the soil enzyme and nutrient, and its distribution of vegetation. In this experiment, the Leymusmolli grown in the coastal windward and leeward slopes was selected as a material, the soil mineral ions, soil nutrients, soil enzyme in the rhizosphere of Leymusmollis were measured to reveal the influence of soil salt on soil nutrient transformation. The results showed that the contents of Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^-, SO^42- in the soil near high tide line（10m） were the highest, especially the content of soil Na+,near the high tide line（10m） was2081.1% higher than that at far high tide line（50m）. The activities of soil invertase,urease enzyme, phosphatase in the soil at far from high tide line（50m） were higher by204.7%, 390.3% and 454.7%, respectively than that of soil near high tide line（10m）,which showed that there were negatively between the enzyme activities and salt ion concentrations in the soil. Similarly, the contents of available nitrogen, available potassium, total potassium, available phosphorus, total phosphorus in the soil at faraway from the high tide line（50m） were higher than that of the soil near high tide line（10m）, the contents of soil available nitrogen, available potassium, total potassium,available phosphorus, total phosphorus at far from the high tide line（50m） increased by 69.7%, 5.5%, 2.6%, 44.9%, 8.1%respectively. It indicated that through inhibiting soil enzyme activity and soil nutrients, the soil salt played an important role in making environmental heterogeneity in the coast.（2） The relationship of photosynthetic characteristics of Leymusmollis grown in coastal dunes of different far from the high tide and wind speed of the enviroment. The growth potential, chlorophyll content, photosynthetic parameters of Leymusmollis in the coastal dunes of different far from the high tide were measured to understand the influence of sea wind on the photosynthesis of Leymusmollis; Results showed that in Summer and Autom, Leymusmollis grown at windward side（30m） of sand dune was shorter and had higher content of chlorophyll;Leymusmollis grown at the Leeward slopes（70m） of sand dune was taller, and had lower in chlorophyll content In the days of no-wind of Autome, the daily average of Pn, Tr, Gs of Leymusmollisin grown on the windward of sand dune were higher than that of inleeward. But in the autumn windy day the Pn, Tr, Gs of Leymusmollis on the windward lower than the days of no-wind, while Pn, Tr, Gs of Leymusmollis on the leeward higher than the days of no-wind, Resulted the Pn, Tr, Gs of Leymusmollis on the leeward higher than on the windward. The lower temperature resulted the higher Pn of no-wind day on the windward, and the high temperature, bad air flow caused the lower Pn of no-wind day on the leeward. On the contrary, under the effect of windy days, may be the ecological factors of the decline of Pn was the decreased stomatal conductance of Leymusmollis on the windward, and the reduction of temperature resulted the Pn of Leymusmollis on the leeward increased. On windy day the average of Pnof Leymusmollisin the windward was higher thanin leeward, but the average of Tr, Gs of Leymusmollis in the windward was lower than in leeward. The study showed that the Leymusmollis grown in coastal dunes of different far from the high tide long-term adapt the different wind of environment changed the photosynthetic metabolism and energy distribution of the Leymus mollis.（3）Relationship between difference in carbohydrate contents of Leymusmollisgrown in near high tide（10m） and far from the high tide（50m） and enviromental heterogeneity in winter and spring. The results showed that Leymusmollis grown at the near high tide line（10m） where there were a higher salt, higher moisture, higher speed of sea wind and low temperatures had stronger and thicker rhizome and shoots, lower foliage, green growth later in spring. But Leymusmollis grown away with the high tide line（50m） where there were lower soil salinity, lower the speed of sea wind, higher temperature had thinner roots, slender branches and leaves, striking root in spring early.It indicated that the morphological plasticity of the Leymusmollis grown in coastal dunes of different far from the high tide were associated with environmental heterogeneity. With temperature reducing in late autumn, the non-structural carbohydrates in the leaves of Leymusmollis grown in coastal dunes of different far from the high tide were transferred to the roots, bud and rhizome which became a“warehouse”. While when soluble sugar e were removed from the roots and rhizomto the bud, the starch contents decreased, and celulose content increased in the roots and rhizome. But there was difference in the carbohydrate transfer and conversion among the Leymusmollis grown in coastal dunes of different far from the high tide.Leymusmollis at the nearly high tide line of 10 m transferred the non-structural carbohydrates from the leaves to the roots earlier in winter, stored more non-structural carbohydrates in the roots, and sprounted later in spring. But it accumulated more cellulose in the leaves, which were correlated with higher resistance to freezing and sea wind; While the Leymusmollis away from the high tide line at 50 m had a longer life period in late autumn. It transferred less non-structural carbohydrate from leaves to roots in winter, stored less non-structural carbohydrate in the roots, and earlier striking root in spring. It induced that the contents of nonstructural carbohydrate in the leaves anf roots was higly associated with its rapid growth and adapting to low salt and speed of sea breeze environment. It suggested that physiological plasticity of carbon metabolism demonstrated by the Leymusmollis grown in coastal dunes of different far from the high tide play an important role in its adaptation to heterogeneous environment, resulting in morphological plasticity, maintaining high ecological amplitude and the formation of multi-resistance.In short, Leymusmollis grown in coastal dunes of different far from the high tide,by adjusting photometabolism and storage and transformation of carbohydrates in organs to adapt to the heterogeneity of the coastal environment. Physiological plasticity of the Leymusmollis play an important role in its adaptation to different soil salt、sea wind、environment temperature and resulting in wind resistance and high ecological amplitude.