Modeled long-term recovery trajectories of soil chemical properties along a post-clearing Chronosequence in the caatinga dry Forest

Clear-cutting for firewood and charcoal production alters soil nutrient availability, salinity, and chemical dynamics in semiarid environments. Soil chemical recovery was evaluated along a regeneration chronosequence in a Caatinga dry forest in northeastern Brazil, comprising six post-clearing ages (0.5, 6, 9, 12, 25, and 50 years) and a reference forest older than 80 years. Soil samples were collected from seven sites at three soil depth intervals (0–5, 5–10, and 10–20 cm), with five spatial subsamples per site ( n = 104). Exchangeable Ca 2 + , Mg 2 + , K + , and Na + , pH, potential acidity, electrical conductivity (EC), cation exchange capacity (CEC), base saturation (BS), sum of bases (SB), total nitrogen (TN), available phosphorus (P), and total organic carbon (TOC) were analyzed. The fitted models indicated that Ca 2 + , Mg 2 + , K + , BS, and TOC recovered more rapidly, reaching 99% of their estimated asymptotes within approximately 36–62 years after clearing, whereas pH and CEC required approximately 164 and more than 300 years, respectively. TN and P also increased asymptotically and required approximately 48 and 52 years, respectively, to reach 90% of their estimated asymptotes. EC and Na + declined progressively throughout regeneration, with greater reductions in the surface layers. These modeled trajectories indicate that soil chemical recovery proceeds at different rates and that nutrient retention capacity may require substantially longer periods than the 15-year cutting cycles currently adopted in the region. Because each regeneration age is represented by a single site and stabilization times beyond the 80-year observed range are model extrapolations, the estimates describe trends within this chronosequence rather than validated thresholds, although they consistently support the inclusion of edaphic indicators in management guidelines for tropical dry forests.