Data: Long-Term Trajectories and Asynchronous Soil Recovery in a Semi-Arid Ecosystem

Forest management in the Caatinga dry forest of northeastern Brazil affects soil carbon and nitrogen stocks, but the recovery dynamics of exchangeable cations, base saturation, and electrical conductivity remain poorly understood. Despite the semi-arid climate and slow vegetation regeneration, Brazilian legislation still allows 15-year cutting cycles, identical to those of humid forests. This study evaluated the suitability of this legal cycle by analyzing soil chemical properties along a chronosequence of hyperxerophilous Caatinga vegetation (0.5, 6, 9, 12, 25, 50 years after clear-cutting and >80-year reference forest). Soil samples (0–5, 5–10, 10–20 cm) were analyzed for pH, total organic carbon (TOC), electrical conductivity (EC), and exchangeable Ca²⁺, Mg²⁺, K⁺, and Na⁺. Soil pH, TOC, and base saturation increased with regeneration time, with logistic models estimating 90% recovery after 48.7, 138.3, and 16.5 years, and 99% recovery after 169.2, 341.5, and 37.9 years. Conversely, EC and Na⁺ decreased throughout the chronosequence, with 99% of their reduction occurring after 78.7 and 71.8 years. TOC showed the slowest recovery rate (B = 0.95), while base saturation responded the fastest (B = 8.98), revealing divergent sensitivities among chemical indicators. Exchangeable Ca²⁺, Mg²⁺, and K⁺ were positively correlated with pH and TOC, whereas Na⁺ and EC exhibited negative associations. Overall, the results indicate that 15-year cutting cycles are insufficient to restore Caatinga soil fertility, allowing recovery of only ~50% of nutrient stocks. Extended fallow periods of at least 35–70 years are necessary to ensure full restoration of soil chemical quality and promote long-term ecosystem resilience.巴西东北部卡廷加旱林（Caatinga dry forest）的森林经营活动会影响土壤碳、氮储量，但可交换阳离子、盐基饱和度以及电导率的恢复动态仍未得到充分解析。尽管该区域属半干旱气候且植被恢复进程缓慢，巴西相关法规仍允许采用15年的采伐周期，该周期与湿润森林的采伐周期完全一致。本研究通过沿旱生性卡廷加植被皆伐后时间序列（皆伐后0.5、6、9、12、25、50年，以及>80年的参照林分）分析土壤化学性质，评估了该法定采伐周期的适宜性。研究采集了0–5 cm、5–10 cm、10–20 cm三个土层的土壤样品，对其pH值、总有机碳（total organic carbon, TOC）、电导率（electrical conductivity, EC）以及可交换性Ca²+、Mg²+、K+和Na+含量进行了分析。结果显示，土壤pH值、总有机碳与盐基饱和度随植被恢复时长增加而升高，经逻辑斯蒂模型估算，三者分别在48.7年、138.3年和16.5年时达到90%恢复水平，在169.2年、341.5年和37.9年时达到99%恢复水平。与之相反，电导率与Na+含量随恢复时间序列推移逐渐降低，其99%的降幅分别在78.7年和71.8年时完成。总有机碳的恢复速率最慢（B=0.95），而盐基饱和度的响应最快（B=8.98），表明不同土壤化学指标间的敏感性存在显著差异。可交换性Ca²+、Mg²+和K+与pH值及总有机碳呈正相关关系，而Na+与电导率则呈负相关关联。整体而言，本研究结果表明15年的采伐周期不足以恢复卡廷加旱林的土壤肥力，仅能恢复约50%的养分储量。若要实现土壤化学质量的全面恢复并维持生态系统长期韧性，至少需要35–70年的更长休耕期。