Intercropping with Pear and Cover Crops as a Strategy to Boost Soil Carbon Sequestration in the Taihang Mountains' Fragile Ecosystems

Hong Wang^1*Chi Zhang¹Shan-shan Tong²Ruifang Zhang^1*Xuguang Li³Xinxin Wang⁴

• ¹College of Land and Resources, Hebei Agricultural University, College of Resources and Environment Science, Hebei Agricultural University, Baoding, China
• ²National Research Center of Agricultural Engineering Technology in Northern Mountainous Areas, Hebei Agricultural University, College of Resources and Environment Science, Hebei Agricultural University, Baoding, China
• ³Cultivated Land Quality Monitoring and Protection Center of Hebei Province, Shijiazhuang, College of Resources and Environment Science, Hebei Agricultural University, Baoding, China
• ⁴College of Horticulture, Hebei Agricultural University, College of Resources and Environment Science, Hebei Agricultural University, Baoding, China

Soil Carbon Sequestration Capacity in Ecologically Fragile Areas of the Taihang Mountains' Gneiss Slopes Demands Immediate Attention. This study evaluated the synergistic effects of land-use transition (from barren hills to cropland to pear orchards) and cover crop intercropping on soil carbon storage through field sampling and experiments at 72 sites in Fuping County, combined with multi-index analysis of soil physicochemical properties and partial least squares structural equation modeling (PLS-SEM). The results showed that land-use transition significantly increased soil carbon storage. The organic carbon storage in the 0-20 cm soil layer of 8-year-old pear orchards reached 26.08 tC/ha, which was 151.89% higher than that of cultivated land (10.35 tC/ha). Meanwhile, soil carbon storage in the 20-40 cm deep layer increased by 83.97% to 13.58 tC/ha. Under the cover cropping pattern, ryegrass in the surface 0-20 cm soil of 8-year-old orchards showed an 18.5% improvement in efficiency compared to natural grass. Conversely, in the 20-40 cm deep soil, the organic carbon content of winter rape increased by 22.43% to 10.59 g/kg. The synergistic gain mechanism was identified as follows: cover crops and root systems increased carbon input, optimized the soil physical structure (bulk density decreased by 5.1%-8.0%, porosity increased by 2.1%-4.1%), and formed a nutrient-carbon pool synergy. Available potassium, phosphorus, and organic carbon were found to be significantly positively correlated. The study demonstrates that, within the Nature-based Solutions (NbS) framework, the pear orchard and cover crop intercropping system vividly exemplifies a practical pathway for addressing climate change through sustainable management and ecosystem improvement. This approach achieves an annual carbon sink growth rate of 4.2-5.8 tC/(ha·a). Its core mechanism lies in constructing a triple synergy of "carbon sequestration enhancement, structural optimization, and nutrient cycling": it not only enhances carbon storage capacity through the plant-soil system but also simultaneously improves soil physical structure and promotes nutrient cycling, achieving multidimensional enhancement of ecosystem services. This practice perfectly embodies the essence of the NbS concept—while strengthening ecosystem carbon sink functions, it cultivates a more resilient agricultural production system, providing a technical paradigm for synergistically advancing carbon neutrality goals and ecological restoration in fragile mountainous areas.