关键词: 毛竹林, 带状改造, 碳循环, 氮循环, 酶活性

Abstract: The abandonment of moso bamboo (Phyllostachys edulis) forests in China has led to significant declines in carbon sequestration capacity and soil quality, necessitating urgent ecological restoration. We used abandoned moso bamboo forests as the control (CK) and established five treatments: light, moderate, and heavy strip transformations (harvesting strip widths of 6, 9, and 12 m, respectively), clear-cutting, and intensive management in Anji County, Zhejiang Province. We examined on the variations of soil carbon, nitrogen contents and enzyme activities in 0-10 cm soil layer, and analyzed the correlations between enzyme activities and soil nutrient contents. The results showed that there was a seasonal pattern in soil carbon and nitrogen contents for all treatments, with summer minima and winter maxima. Soil enzyme activities exhibited an adverse pattern. Compared with CK, light and moderate strip transformations significantly increased soil organic carbon (SOC) by 8.5% and 10.3%, and enhanced total nitrogen (TN) by 6.7% and 10.0%, respectively. Heavy strip transformation, clear-cutting, and intensive management reduced SOC by 3.8%-6.7%, but did not affect TN. The soil carbon pool management index (CPMI) increased by 4.4% and 8.9% under light strip transformation and intensive management, respectively, while decreased by 1.7%-3.6% under other treatments. For carbon-cycling enzymes, light and moderate strip transformations and intensive management enhanced ligninase/cellulase activities by 6.5%-10.7%, whereas heavy strip transformation and clear-cutting reduced them by 3.6% and 11.9%, respectively. β-glucosidase activity significantly increased in all treatments except for light strip transformation. For nitrogen-cycling enzymes, all treatments significantly elevated urease and N-acetyl-β-D-glucosaminidase (NAG) activities. The leucine aminopeptidase (LAP) activity significantly increased only in heavy strip transformation, clear-cutting, and intensive management. Multivariate adaptive regression splines (MARS) modeling results showed that urease, NAG, LAP, and harvesting strip width were key drivers of soil carbon and nitrogen dynamics. When the strip width was ≤ 9 m, an increase of 1 m in width would enhance SOC and TN content by 0.54 and 0.04 mg·g^-1, respectively. In summary, harvesting strip width significantly influenced soil carbon and nitrogen contents and related enzyme activities, and jointly regulated soil carbon and nitrogen contents with soil enzyme activities. We suggested 6-9 m as the optimal harvesting strip width for bamboo forests restoration.

Key words: moso bamboo forest, strip transformation, carbon cycle, nitrogen cycle, enzyme activity