Shoot Phenology,Growth Dynamics And Allocation Of Recently Fixed Carbon Of Chinese Fir Seedlings In Responses To Simulated Air And Soil Warming

No doubt about it,the world is warming.Temperature control many biochemical reaction rate in the ecosystem,and affects many ecological processes and functions,so understanding and predicting forest tree species to climate warming and the response is necessary.A warming experiment was set up in Chinese fir(Cunninghamia lanceolata)seedlings subplots in Chenda Nation-Own Forest Farm,Sanming,Fujian Province,which included four treatments:control(CT),soil warming(W),air warming(OTC),air and soil warming(OTC-W).The objective of this study were to examine the effect of whole ecosystem warming(air and soil warming)on shoot phenology,growth,photosynthetic characteristics,leaf traits,stoichiometry and allocation of recently fixed carbon of Chinese fir seedlings.Our study showed that Air warming significantly effect on Chinese fir seedlings phenology,but soil warming did not impact.Bud break and leaf unfolding was significantly advanced in OTC and OTC-W than other treatments.W and CT their phenology date did not differ significantly.Air warming extended the length of the growing season of tree height and shoot elongation,and greater their growth rate.In general,a greater growth rate for OTC-W than other treatments.Empirical results from our study suggest that air and soil warming causes an earler phenology and greater growth rate and longer growing season,should increase productivity and carbon uptake by Chinese fir in a warmer climate.There was no significant effect of simulated warming on Chinese fir seedlings photosynthetic rate in our study.But air warming and soil warming were increased water use efficiency.Indicate water use efficiency(WUE)response to warming is relatively more sensitive.Air warming significantly increased specific leaf area and leaf water content of Chinese fir seedlings.Our results showed that the response of leaf morphological characteristics of crruent neddle to warming were consistent with the response of 1 year old needle.But the ecological stoichiometry characteristics were dramatically different.Air warming significantly increased leaf nitrogen content and soil warming was just significantly increased the leaf nitrogen content of crruent neddle,and did not significant effect on 1 year old needle.Air warming did not significant effect on leaf phosphorus content,soil temperature increased the leaf phosphorus content of crruent neddle.Air warming lead to reduced leaf C:N ratio,and slightly increased leaf N:P ratio,in addition 1 year old needle N:P ratio above 14 in April,others were bellow 14,this revealed that Chinese fir seedlings growth was limited by nitrogen.While the increased leaf N:P ratio of crruent neddle can alleviate Chinese fir growth limited by nitrogen.Used a 13CO2 pulse-labelling approach found that air warming probably caused Chinese fir seedlings will allocation more recently fixed photoassimilates to the aboveground,and the soil warming decreased belowground recent photoassimilates allocation.Our study suggests that air warming advanced the phenology and promoted the growth of Chinese fir seedlings,and soil warming did not impact,air and soil whole warming promoted greater the growth of Chinese fir seedlings,showed that more conducive to Chinese fir plantation productivity and increase carbon sinks function.