The Response Of Dark Respiration For Larix Gmelinii Needles To Climate Warming

Leaf dark respiration is an important part of forest ecosystem carbon cycle,and its response to climate warming and feedback are hot problem in the study on ecology.Dahurian larch(Larix gmelinii)trees are the dominant species of the boreal forest and are sensitive to climate warming,and it is the ideal choice of studing dynamic response of leaf dark respiration to climate change.In this study,the seedlings of Dahurian larch in 4 latitudes were transplanted to the southern edge of the distribution areas,constituted four warming treatment.To study the response of leaf dark respiration to climate warming by measuring dark respiration rate of Dahurian larch needles in different latitudes and months.The effect of warming on dark respiration temperature sensitivity(Q10)of Dahurian larch needles was also discussed,and it is helpful to understand the adaptation strategies of respiration of tree species to climate warming,as well as to more rationally assess the carbon reserves of forest ecosystems in the future.The main conclusions are as follows:There was no significant difference in dark respiration rate per unit area(Rd-a)and dark respiration temperature sensitivity coefficient(Q10)between the dark treatment in daytime and nighttime measurements.Dahurian larch needles responded to climate warming by decreasing the dark respiration rate and increasing the dark respiration temperature sensitivity,and the responses of Dahurian larch to warming were different in 4 latitudes.After warming,under the standard temperature of 25?,the dark respiration rate per unit mass(R25-m),dark respiration rate per unit nitrogen(R25-N),specific leaf area(SLA)and Q10 of Dahurian larch needles in 4 latitudes have significant differencehe(P<0.05).But the northern margin of the distribution area of Dahurian larch has the minimal reduction of Rd-a and the change rate of Q10(P<0.05).R25-a and Q10 ave significant positive correlation with nitrogen content(N)and soluble sugar(SS)of needles.The difference of leaf N,SS and climatic conditions in original sites of Dahurian larch are the main reason for the difference in response of Rd-a and Q10 to warming.Monthly warming reduced Rd-max?R15-a and R25-a of Dahurian larch,but increased the Q10.Dark respiration rate is higher in early and late growth season,but the Q10 is lower.there are different trends in N and SS with Rd-a,but N and SS have the same change rule with Q10.The Rd-a and Q10 in the peak growth season are significantly different from other months(P<0.05).This study shows that the Rd-a and Q10 of Dahurian larch needles measured by dark treatment in the daytime can replace the results measured at night within a specific temperature range(15?-40?).The changes in nutrient content of Dahurian larch and the long-term adaptation of trees to the local climate are the reasons for the differences in warming response of Q10.Month dynamics and location differences should be considered when studying the effects of climate warming on dark respiration of Dahurian larch.In addition,the following assumptions were made in this study:(?)Dahurian larch responds to climate warming by reducing the rate of dark respiration.(?)the southern edge of the distribution area is more responsive to warming than tree species on the northern edge,so it has lower respiratory temperature sensitivity.(?)Seasonal warming will increase the dark respiration temperature sensitivity of Dahurian larch.