Tolerance And Adaptation Mechanism Of Main Wind And Sand-fixing Tree Species To Wind Blowing And Wind-drift Blowing On Coastal Sandy Land In Shandong

There were frequent strong wind blowing,typhoons,and wind-drift blowing in the coastal,which had seriously made air pollution,destroyed production facilities and coastal landscapes.Wind-drift blowing seriously endanger the local economic development and ecological security.The state has always attached great importance to the treatment of coastal environment and vegetation construction.At present,people are not clear about the tolerance of different plants to strong winds and wind-drift blowing.However,people don't understand its ecological adaptation mechanism and physiological response law.It is difficult for people to select windproof and sand-fixing tree species suitable for planting in coastal sandy land and affect the construction of coastal windbreak forests.In this paper,the dominant species for wind and sand-fixing tree species,Pinus thunbergii and Amorpha fraticosa were used as materials.By using outdoor portable wind tunnel,we carried out clean wind and wind-drift blowing tests and intermittent clean wind and wind-drift blowing tests at different times and intensities.We studied the tolerance and critical death characteristics of two tree species to high winds and strong winds.We analyzed its ecological adaptation strategies and physiological response mechanisms to different time and intensity of wind and sand flow stress.We explore the role of its physiological regulation of wind resistance in its wind resistance,and clarify its physiological and ecological adaptation mechanism to the wind and sand environment.It is expected to provide theoretical guidance for the selection and cultivation of windproof and sand-fixing tree species in the sandy land of the northern coast of China.The results are as follows:?1?Physiological response of Pinus thunbergii seedlings to wind blowing and wind-drift blowing at different wind speed:In order to understand how physiological and ecological responses of Pinus thunbergii seedlings to wind blowing and wind-drift blowing,we designed treatments of different wind speed?6,9,12,15,and 18m/s?,different wind-drift blowing(0,1.00,28.30,63.28,111.82,and 172.93 g.cm^-1.min^-1),and five wind blowing times?10,20,30,40 and 50min?in spring,2018 in Yantai,Shandong Province by using outdoor portable wind tunnel.The relative water content?RWC?,malondialdehyde?MDA?contents,membrane permeability,osmotic regulators,soluble sugar,proline,and antioxidant enzyme activities?SOD,CAT,POD?were tested in the leaves of seedlings of Pinus thunbergii under the previous treatments.The results showed that under low and medium wind speeds,the changes of various stress resistance physiological indexes of Pinus thunbergii were small,which may be related to the strong dehydration resistance of Pinus thunbergii needles and the maintenance of high water content in the leaves.The sand loss caused by the wind and sand flow not only can quickly promote the accumulation of proline content of Pinus thunbergii and maintain the soluble sugar content to maintain the water balance in the cell.It was also quickly activate the antioxidant protection enzyme system,by improving the protection enzyme activity,removal oxygen free radicals,inhibits membrane lipid peroxidation,protects the integrity of cell membranes and enables them to survive a blown sandstorm.?2?Physiological response of Amorpha fruticosa seedlings to wind blowing and wind-drift blowing at different wind speed:The method is the same as above.The results showed that in the middle wind speed net wind blow,it presented that water shortage triggered by wind blowing and wind-drift blowing induced quickly antioxidant defense system and promote the accumulation of osmotic regulator in the leaves of Amorpha fruticosa.It was play an important role in physiological regulation to maintaining water balance and protective effects in its resistance wind blowing to growth.However,in the wind and sand flow,the physical damage resulted in sand particles to the abrasion of the leaves caused increased water loss of the leaves.It is leading to physiological and metabolic disorders,which reduced the activity of antioxidant enzymes and the content of osmotic regulators.Therefore,the ability of Amorpha fruticosa to resist wind and sand flow is limited.?3?Physiological response of Amorpha fruticosa and Pinus thunbergii seedlings to interval strong wind blowing and wind-drift blowing:In this study,intermittent wind blasting treatment?10min each time,24h interval,continued for 3d?leaf moisture content,MDA,soluble sugar,proline content,antioxidant enzyme activity?SOD,CAT,POD?measurement to reveal regulation mechanism of Pinus thunbergii and Amorpha fruticosa against wind growth and wind-blown sand plant self-healing repair.The results showed that the Pinus thunbergii relies on its coniferous wind and leaf oil protection to make it have strong resistance to dehydration,and the large and thin leaves of Amorpha fruticosa have poor resistance to dehydration.In self-healing restoration,both tree species quickly adjust the content of soluble sugar and proline according to the water conditions in the leaves,and increase the POD and CAT?Amorpha fruticosa?and SOD?Pinus thunbergii?.Therefore,different tree species play an important role in the physiological regulation of self-healing repair after strong winds by adjusting the content of osmotic regulators and protecting enzyme activity to maintain the metabolic balance of water and oxygen radicals.?4?The effect of wind and sand flow with different intensities on the leaf surface of Pinus thunbergii and Amorpha fruticosaIn this study,the tissue blocks of about 5mmx5mm on both sides of the veins of Pinus thunbergii and Amorpha fruticosa under different sand treatments were cut and observed under the SU8010 scanning electron microscope.The damage situation of the leaf epidermis at 20min and 40min under 6m/s,12m/s and 18m/s wind speed was analyzed.The results showed that with the increase of wind speed intensity and duration of wind blowing,the thickness of the Pinus thunbergii leaf epidermis and cuticle thickness increased,and the diameter of the duct increased.However,the leaves of Amorpha fruticosa showed cuticle thickness,increased epidermal hair density,cracked leaf epidermis,and decreased stomatal area.It shows that the two tree species of different families and genera adapt to the morphological and anatomical structure of wind and sand stress,which is the key to their survival in the coastal environment.?5?Comparative study on resistant thresholds of coastal tree species with windproof and sand fixing to strong wind blowing and wind-drift blowing:The ratio of leaf deciduous,changes in leaf morphology,color,stem morphology in the Amorpha fraticosa and Pinus thunbergii were investigated during and after expose to strong wind blowing and wind-drift blowing(at 18m/s with 172.93g.cm^-1.min^-1)for short-term treatment?40min?and interval treatment?10min,reparing24h,recycling 3 times?,and long-term 6h treatment by using methods of combination of outdoor portable wind tunnel with field investigation.The tolerance threshold of two tress species were evaluated by pant morphology trait,bend and breakage of stems or branches,leaf shedding ratio,plant survival rate by field investigation after treatment in the fall and winter,and spring next year.The results showed,?1?Two tress all restored and had leafy in next spring,exhibited higher tolerance to strong wind blowing after short-term treatment with strong wind blowing and wind-drift blowing.?2?During interval strong wind blowing and wind-drift blowing,there were leaves of the two tree species partly fell off,the tops of the plants damaged,and the stems bent,but they all survived in the second year and exhibited higher tolerance to strong interval wind blowing.?3?Under long-term treatment with wind blowing and wind-drift blowing for 6h,there were differences in capacity of tolerance to it between two tress.Pinus thunbergii was survival,and Amorpha fraticosa was dead under wind-drift blowing,The tolerance threshold was Pinus thunbergii>Amorpha fruticosa.Therefore,they can be used as the preferred tree species for the construction of coastal and coastal protection forests.