Effects of Forest Land Mulching on the Soil CO2 Emission Rate of Phyllostachys violascens Forests

This study investigates the dynamics of soil CO2 emissions during the cover period of Phyllostachys violascens and the impact of different cover measures, aiming to provide references for reducing the environmental effects of bamboo cover. An L27 (913) orthogonal experimental design was employed, setting the following variables: (1) heating materials: chicken manure, straw cake, and wheat ash; (2) thickness of husk layer: 15 cm, 25 cm, and 35 cm; (3) soil moisture levels before covering: moisture to 10 cm, 15 cm, and 20 cm. The soil CO2 emission rate showed a unimodal curve, with a significant overall increase during the cover period. Throughout the entire cover period, the average soil CO2 emission rate (25.39 μmol·m−2·s−1) was 5.1 times higher than that of the uncovered Lei bamboo forest (5.02 μmol·m−2·s−1) during the same period. Thicker husk layers (25 cm and 35 cm) corresponded to higher soil CO2 emission rates, with significant differences noted among the thicknesses. When the soil was moist to 10 cm, the CO2 emission rate was highest (62.51 μmol·m−2·s−1); moisture to 15 cm and 20 cm resulted in significantly lower emission rates. Chicken manure produced the highest peak CO2 emissions in the third week, at 70.64 μmol·m−2·s−1, while straw cake and wheat ash reached their peaks in the fifth week, at 66.56 μmol·m−2·s−1 and 57.58 μmol·m−2·s−1, respectively. The interactions between the three factors (heating materials, husk layer thickness, and moisture levels) significantly affected the soil CO2 emission rates. By optimally configuring these factors, CO2 emissions can be regulated. This study recommends using wheat ash or straw cake as heating materials, combined with a 25 cm husk layer thickness, and moistening the soil to 15 cm before covering. This approach effectively reduces the peak and total soil CO2 emissions while ensuring suitable soil temperatures for the growth of bamboo shoots in spring. This research provides a scientific basis for the environmental management of bamboo forests, aiding in the optimization of covering measures to achieve low-carbon and sustainable bamboo management.