[Objective ] Vegetation type is one of the key factors affecting soil respiration. This study aimed to measure and compare soil respiration rates of young plantations of Populus simonii × P. nigra and Amorpha fruticosa established on black soils with different degradation levels, and to analyze the effects of environmental factors on soil respiration of young plantations, in order to clarify the differential roles of these tree-type and shrub-type restoration measures in soil carbon emission from degraded black soils.[Methods] From May to October 2024 (on degradation gradients constructed in 2022), soil respiration rates were continuously measured in situ using a portable soil carbon flux system (LI-870) at Keshan Farm, Qiqihar. Mildly, moderately and severely degraded black soils were planted with Populus simonii × P. nigra and Amorpha fruticosa young plantations, with corresponding bare control plots; all plots had an area of 4 m × 7 m. Soil respiration rates of the two plantations and the controls were compared among degradation levels, and the underlying mechanisms were further explored using Pearson correlation analysis, redundancy analysis (RDA) and partial least squares path modeling (PLS-PM). [Results] Vegetation type, soil degradation level and their interaction had highly significant effects on soil respiration rate (P < 0.001). For both plantations, soil respiration on all three degradation levels showed pronounced seasonal dynamics, with maxima in July and August. The mean soil respiration rates of Populus simonii × P. nigra , Amorpha fruticosa and the control all decreased significantly with increasing degradation degree (P < 0.05). Across degradation levels, the mean soil respiration rate in Amorpha fruticosa plantations (2.31 μmol CO? m?2 s?1) was generally higher than that in Populus simonii × P. nigra plantations (1.96 μmol CO? m?2 s?1). Model fitting showed that soil temperature at 5 cm depth was exponentially and significantly related to soil respiration, whereas soil volumetric water content alone was not significantly correlated with soil respiration, but its interaction with temperature significantly affected soil respiration in the different plantations (P < 0.05). Pearson's correlation analysis showed a highly significant positive correlation (P < 0.01) between Rs and soil 5 cm temperature and alkali-hydrolyzable N. RDA indicated that soil respiration rate was significantly and positively correlated with total N, available P, total P, alkali-hydrolyzable N, 5-cm soil temperature and volumetric water content (P < 0.05). PLS-PM further showed that plant species and soil degradation degree affected soil respiration both directly and indirectly through their effects on soil temperature and soil nutrients. [Conclusion ]Establishing young plantations of Populus simonii × P. nigra and Amorpha fruticosa significantly increased soil respiration rates of degraded black soils compared with bare controls (P < 0.05), and in mildly degraded soils the mean soil respiration under Amorpha fruticosa plantations was significantly higher than under Populus simonii × P. nigra (P < 0.05). Soil temperature is the key factor driving the temporal variation of soil respiration, and, through its coupling with soil nutrients, it mediates the effects of plant species and soil degradation degree on soil respiration.