Spatial Variation And Influencing Factors Of Leaf Dark Respiration And Temperature Sensitivity In Terrestrial Ecosystems In China

Plant dark respiration is considered to be an important part of the biosphere in response to global climate change.With the changes in the balance of photosynthesis and respiration,the carbon flux in plant ecosystem will also change.The temperature sensitivity of plant respiration(Q₁₀)is a relational parameter in the ecosystem.Therefore,understanding the spatial distribution and influencing factors of plant leaf respiration and its temperature sensitivity is helpful to understand how environmental change affects the carbon exchange between ecosystem and atmosphere,and is of great significance to predict the carbon cycle of ecosystem under climate change.Taking 2698 leaves from 22 locations in different regions of China and the respiration rate and temperature sensitivity of 469 species at 10-45℃as the research object,this paper studies the spatial variation characteristics and influencing factors of plant leaf respiration and respiratory temperature sensitivity(Q₁₀)under different environments.The main conclusions are as follows:（1）The spatial variation range of plant leaf respiration rate(R_area)based on leaf area at the same temperature is 0.157-6.021μmol/m²/s,mainly 0.4-1.4μmol/m²/s,there were significant differences among life forms;The spatial variation range of plant leaf respiration rate(R_mass)based on leaf mass at the same temperature is 1.685-119.284μmol/kg/s,mainly concentrated in 5-25μmol/kg/s,there was significant difference between woody plants and herbs,but there was no significant difference between shrubs and trees;The spatial variation range of temperature sensitivity(Q₁₀)of plant leaf respiration is 1.37-2.87.The data are mainly concentrated between 1.6-1.9,and there are significant differences among different life forms.（2）At the same temperature,plant leaf respiration rates(R_area and R_mass)decreased with the increase of longitude and increased with the increase of latitude and altitude.The correlation between altitude and respiration rate was the highest,and the correlation of respiration rate of plants with different life forms was consistent with the whole.The temperature sensitivity(Q₁₀)of plant leaf respiration increased with the increase of altitude and decreased with the increase of longitude,but there was no significant difference between latitudes.The correlation of different life forms was consistent with the whole.（3）Under the same temperature,plant leaf respiration rate(R_area and R_mass)decreases with the increase of annual average temperature,annual precipitation and relative humidity,and increases with the increase of sunshine hours and daily range.The correlation of respiration rate of plants in different life forms is consistent with the whole.The correlation coefficient between respiration of arbor plants and climate factors is the highest in different life forms.The temperature sensitivity(Q₁₀)of plant leaf respiration decreases with the increase of annual average temperature,annual precipitation and relative humidity,and increases with the increase of sunshine hours and daily range.When comparing plants of different life forms,the correlation coefficient between temperature sensitivity(Q₁₀)of woody plants and climate factors is more than that of herbaceous plants.（4）At the same temperature,plant leaf respiration rate(R_area and R_mass)increased with the increase of non-structural carbohydrate（NSC）,leaf total nitrogen content and leaf p H.the correlation between respiration rate R_area and carbon content was not significant,but the respiration rate R_mass decreased with the increase of carbon content.R_area of herbaceous plants and R_mass of woody plants were significantly positively correlated with NSC,while the correlation of other respiratory rates was not significant;There was a significant negative correlation between R_mass and carbon content of herbs and shrubs,but there was no significant correlation between other respiratory rates;The correlation between respiration rate and total nitrogen content in leaves of plants with different life forms was consistent with the whole,and they were significantly correlated;There was a significant positive correlation between respiration rate and leaf p H in herbs and trees,but not in shrubs;On the whole,the correlation between respiration rate and water potential is not significant.The correlation between respiration rate and water potential of woody plants is significant,but the correlation coefficient is low,and has no significant relationship with herbs.The temperature sensitivity(Q₁₀)of plant leaf respiration decreased with the increase of water potential and increased with the increase of leaf total nitrogen content.There was no correlation between other leaf traits（total carbon,p H and non＿structural carbohydrate NSC）and temperature sensitivity(Q₁₀)of plant leaf respiration.（5）Under the same temperature,plant leaf respiration rate R_area is mainly affected by life form,altitude,sunshine hours,relative humidity,non-structural carbohydrate,water potential and leaf total nitrogen content.Among them,relative humidity has the greatest impact on R_area and leaf total nitrogen content has the least impact on R_area;Under the same temperature,plant leaf respiration rate R_mass is mainly affected by annual precipitation,leaf total carbon content and leaf total nitrogen content.Among them,leaf total nitrogen content has the greatest impact on R_mass,and leaf total carbon content has the least impact on R_mass;The temperature sensitivity（Q10）of plant leaf respiration is mainly affected by life form,latitude,altitude,daily range and leaf p H,among which altitude has the greatest impact on Q10 and leaf p H has the least impact on Q₁₀.