There is great significance for the research on the components separation of soil respiration in response to climate change. The trench method had been used in our study to separate components of soil respiration in two typical shelter forestlands,i.e. Poplar (Populus tomentosa Carr.) plantation and Water fir (Metasequoia glyptostroboides Hu & Cheng) plantation, in a silting costal area of Northern Jiangsu Province. It was showed that there were similar seasonal dynamics for root respiration, heterotrophic respiration and total soil respiration in both plantations: higher respiration rate between Jun. and sept. and lower in the other months; the annual CO2 flux of root respiration of Poplar and Water fir plantations was 7675 g m-2 and 902.8g m-2,respectively, which was far less than that of the corresponding annul heterotrophic respiration flux that was 2.9 and 2.0 times larger than that of the corresponding root respiration components, respectively. In both plantations, temperature was the key limiting factors for both of the soil respiration components, but soil water content was not the control factor in the experiment period. Our results showed that in this silting coastal area, root respiration contributed less to the total soil respiration than the heterotrophic component for both shelter forests. To estimate the contribution of components to the total soil respiration more accurately, isotope method should be used in the future studies.