Study On The Upper Limit Of Plant Climate Space Under The Influence Of Multiple Factors

High temperature and drought stress are the main limiting factors for plant growth and development,and the upper limit of climatic space of plants can reflect the change of temperature index under high temperature stress with light,humidity,wind and other meteorological factors.Therefore,this study selected quercus variabilis seedlings of representative tree species and representative crop winter wheat in temperate hilly regions to study the upper limit of plant climate space.By analyzing two kinds of plants under the condition of different wind speed and soil moisture,leaves the temperature difference(leaf temperature and air temperature difference value)and the tendency of the relationship between solar radiation and regularity,thus establishing the leaf temperature under different wind speed and soil moisture conditions of poor alignment and climate space limit column line,eventually establish two plants three-dimensional climate space limit diagram.The research results show that:(1)Under the conditions of different wind speed and soil humidity,the temperature difference between the leaves of quercus variabilis seedlings and winter wheat presented a good linear relationship with solar radiation,in which the temperature difference between the leaves of quercus variabilis seedlings increased with the increase of solar radiation.When the soil moisture of winter wheat is high,with the increase of solar radiation,the temperature difference among leaves decreases gradually.(2)Under the condition of different wind speed and soil humidity,the slope of temperature difference line of seedling leaves of quercus variabilis is affected by both soil humidity and wind speed.When the wind speed is 0m/s(static wind),0.4m/s,and1.2m/s,the slope is greatly affected by the soil humidity,and when the wind speed is1.5m/s,the slope is greatly affected by the wind speed.Under the condition of static wind,when the soil moisture is less than 11%,it is affected by the soil moisture.When the soil moisture is more than 11%,the slope has no significant correlation with the soil moisture.The soil moisture of 11% is a sign that winter wheat enters the initial drought stage at jointing stage and enters the initial drought stage at filling stage when the soil moisture is less than 20%.(3)According to the heat balance equation,the convective heat transfer coefficient of the seedlings of Quercus variabilis under different wind speeds was inversely calculated.The convective heat transfer coefficient of the seedlings of Quercus variabilis was 33w/(m~2.?)at the wind speed of 0.4m/s.The convective heat transfer coefficient of the leaf is 79 w/(m~2.?)at 1.2m/s wind speed.The convective heat transfer coefficient of the leaf is 90 w/(m~2.?)at 1.5 m/s wind speed,and the convective heat transfer coefficient has a good linear relationship with the wind speed.(4)The upper limit of three-dimensional climate space of quercus variabra seedlings under the influence of solar radiation,air temperature,soil moisture and wind speed and the upper limit of three-dimensional climate space of winter wheat under the influence of three factors,namely solar radiation,air temperature and soil moisture,were established by the graphical method.It can be seen from the upper limit diagram of climate space that the change rules of each factor are obvious.At lower soil moisture(drought intensification),the climatic space becomes smaller.At lower wind speeds,the climate space becomes smaller.(5)Comparing the upper limit of climatic space of the two plants,it was found that the climatic space suitable for the survival of quercus variabilis seedlings was larger than that of winter wheat,indicating that its resistance to high temperature was larger than that of winter wheat.This study determined the upper limit map of three-dimensional plant climate space for quercus variabilis seedlings and winter wheat.The upper limit map of climate space can more clearly reflect the change rules of four conventional agrometeorological factors affecting leaf temperature and the climate space size suitable for plant survival.The results of this study are conducive to monitoring and evaluating the degree of plant stress by using conventional meteorological data,and provide a theoretical basis for the adoption of artificial control measures to reduce the stress on plants caused by high temperature and drought.