<b>Legacy effects of long-term autumn leaf litter removal slow decomposition rates and reduce soil carbon in suburban yards</b>

Seasonal senesced leaf litter removal eliminates considerable organic material from suburban soils annually. We test if this disturbance alters decomposition and carbon cycles and depletes soils of organic matter over time, creating persistent legacy effects.We used a factorial experimental design to implement 1-2 years of current leaf litter manipulations (remove or retain fallen leaves) within historically raked and unraked yard areas in suburban Maryland yards. We then compared total organic soil carbon and decomposition using a standardized substrate decomposition methodology (Tea Bag Index) across treatment plots.Long-term litter removal in suburban yards reduced decomposition rates by 17% and total soil organic carbon concentration by up to 24% compared to areas where leaf litter was retained in situ. In contrast, short-term management changes (1-2 years) did not significantly impact decomposition rates or total organic soil carbon concentrations.Our findings suggest that long-term suburban litter raking creates legacy effects that alter decomposition and carbon storage process trajectories that are not easily reversed. This is important in understanding urban ecosystem function and sustainable management.季节性凋落叶移除每年都会从城郊土壤中清除大量有机物质。本研究旨在探究这类扰动是否会随时间推移改变土壤分解与碳循环过程，并消耗土壤有机质，进而产生持续的遗留效应。本研究采用析因实验设计，在马里兰州城郊的长期清叶与不清叶庭院区域内开展为期1-2年的凋落叶操控实验（移除或保留落叶），随后通过标准化底物分解方法（茶袋指数法，Tea Bag Index）对比各处理样地的土壤总有机碳含量与分解速率。研究结果显示，与原位保留凋落叶的区域相比，城郊庭院长期移除凋落叶会使分解速率降低17%，土壤总有机碳浓度最高下降24%；与之相对，短期管理措施调整（1-2年）并未对分解速率或土壤总有机碳浓度产生显著影响。本研究结果表明，城郊庭院长期清叶会产生遗留效应，改变分解与碳储存过程的轨迹，且这类效应难以逆转。这一发现对于理解城市生态系统功能与可持续管理具有重要意义。