Wu Jianghong, Gong Xianghuan, Shu Yingge
College of Agronomy, Guizhou University, Guiyang, Guizhou, China.
PeerJ. 2024 Dec 20;12:e18582. doi: 10.7717/peerj.18582. eCollection 2024.
Nitrogen mineralization plays a critical role in the ecosystem cycle, significantly influencing both the ecosystem function and the nitrogen biogeochemical cycle. Therefore, it is essential to investigate the evolutionary characteristics of soil nitrogen mineralization during the karst vegetation restoration to better understand its importance in the terrestrial nitrogen cycle.
This study analyzed from various stages of vegetation growth, including a 40-year-old woodland, 20-year-old shrubland, 15-year-old shrubland, 5-year-old grassland, and nearby cropland. The aerobic incubation technique was used for 35 days to evaluate soil N mineralization characteristics and their correlation with soil environmental factors. The study focused on examining the variations in soil N mineralization rate (NMR), N nitrification rate (NR), net nitrification rate (AR), and NH -N and NO -N levels.
Nitrate nitrogen, the primary form of inorganic nitrogen, increased by 19.38% in the 0-40 cm soil layer of the 20-year-old shrubland compared to the cultivated land. Soil NH -N levels varied during the incubation period, decreasing by the 14 day and rising again by the 21 day. Soil NO-N and total inorganic nitrogen levels initially increased, then declined, and eventually stabilized, reaching their highest levels on the 14 day. During vegetation restoration, the soil NR and NMR decreased gradually with increasing incubation time. The 15-year shrub, 20-year shrub, and 40-year woodland showed the potential to increase soil NR and NMR. Furthermore, the 15-year shrub and 20-year shrub also increased soil AR. The Mantel test analysis indicated positive correlations among total nitrogen (TN), total phosphorus (TP), total potassium (TK), silicon (Si), AR, NR, and NMR. While available phosphorus (AP) and NMR demonstrated positive correlations with NR and NMR. Furthermore, TN, TP, TK, and Si were found to be positively correlated with AR, NR, and NMR, whereas AP and NO -N showed negative correlations with AR, NR, and NMR. It is worth noting that NH -N had the greatest effect on AR, while the bulk density (BD) significantly affected the NR. Furthermore, ammonium nitrogen (AN) and soil organic carbon (SOC) were identified as the primary contributors to NMR. This study provides a theoretical basis for comprehending the influence of vegetation restoration on soil nitrogen mineralization and its role in ecosystem restoration.
氮矿化在生态系统循环中起着关键作用，对生态系统功能和氮生物地球化学循环都有显著影响。因此，研究喀斯特植被恢复过程中土壤氮矿化的演变特征，对于更好地理解其在陆地氮循环中的重要性至关重要。
本研究分析了植被生长的各个阶段，包括40年生林地、20年生灌丛地、15年生灌丛地、5年生草地以及附近的农田。采用好气培养技术进行35天，以评估土壤氮矿化特征及其与土壤环境因素的相关性。该研究重点考察了土壤氮矿化速率（NMR）、氮硝化速率（NR）、净硝化速率（AR）以及NH₄⁺-N和NO₃⁻-N水平的变化。
与耕地相比，20年生灌丛地0-40厘米土层中无机氮的主要形式硝酸盐氮增加了19.38%。土壤NH₄⁺-N水平在培养期间有所变化，在第14天下降，在第21天再次上升。土壤NO₃⁻-N和总无机氮水平最初上升，然后下降，最终稳定，在第14天达到最高水平。在植被恢复过程中，土壤NR和NMR随着培养时间的增加而逐渐降低。15年生灌丛、20年生灌丛和40年生林地显示出增加土壤NR和NMR的潜力。此外，15年生灌丛和20年生灌丛也增加了土壤AR。Mantel检验分析表明，全氮（TN）、全磷（TP）、全钾（TK）、硅（Si）、AR、NR和NMR之间呈正相关。有效磷（AP）与NMR与NR和NMR呈正相关。此外，发现TN、TP、TK和Si与AR、NR和NMR呈正相关，而AP和NO₃⁻-N与AR、NR和NMR呈负相关。值得注意的是，NH₄⁺-N对AR的影响最大，而容重（BD）对NR有显著影响。此外，铵态氮（AN）和土壤有机碳（SOC）被确定为NMR的主要贡献者。本研究为理解植被恢复对土壤氮矿化的影响及其在生态系统恢复中的作用提供了理论依据。
