In order to reveal the effects of forest succession and climate warming and their interactions on soil autotrophic respiration and plant root respiration at different forest levels

4 natural secondary forests (Poplar-birch broad-leaved deciduous forest

Pinus tabulaeformis conifer broad-leaved mixed forest

Larix principis rupprechtii forest and Picea asperata forest) at different succession stages in Guandi Mountain were studied. From 2016 to 2019

Li-6400 portable analyzer was used to observe the changes of plant root respiration and soil autotrophic respiration rates at different levels of each forest type during the growing season. Greenhouse heating method was used to simulate the effects of temperature increase on autotrophic respiration and its components. The results showed that:(1) The root respiration rate and soil autotrophic respiration rate decreased with succession

and the contribution rate of soil autotrophic respiration to total soil respiration increased significantly with succession. The contribution rate of root respiration to soil autotrophic respiration increased significantly in arbor layer

but decreased significantly in shrub layer and herb layer. (2) Warming significantly increased soil autotrophic respiration ranging from 8.48% to 8.76% in different successional stages

and soil autotrophic respiration gradually increased with the successional process. The response of root respiration rate to warming was different in different forest layers. Warming significantly increased root respiration rate in herb layer (10.88%~14.00%) and shrub layer (8.37%~15.26%)

but it had no significant effect on root respiration rate of arbor layer. Increasing temperature decreased the contribution rate of soil autotrophic respiration and root respiration in arbor layer

while it increased the contribution rate of root respiration in herb layer. (3) Warming and succession did not change the variation law of soil autotrophic respiration and its components in the growing season

but it had significant coupling effects on soil autotrophic respiration

herb layer and shrub layer plant root respiration. In conclusion

soil autotrophic respiration rate and root respiration rate of shrub layer and herbaceous layer had significant response to temperature increase

and had significant coupling effect on the interactive process of succession and temperature increase

which provide data support and theoretical basis for the study on the effect of forest regeneration process on forest soil carbon emission under the background of climate warming.