Nyirenda Harrington
Ministry of Agriculture, Irrigation and Water Development, Salima Agricultural Development, Division, Private Bag 1, Salima, Malawi.
Heliyon. 2020 Oct 19;6(10):e05254. doi: 10.1016/j.heliyon.2020.e05254. eCollection 2020 Oct.
Reclamation of degraded land using revegetation is one way of sequestering carbon into the soil. In this study an assessment was done to estimate the status of soil carbon amounts after revegetation with trees and grass in South West Iceland (Hafnarmelar). Natural woodland and eroded plots were part of the assessed plots as controls making four treatments. Soil samples were analysed for bulk density, carbon content and soil texture. Total % carbon (C) was analysed using vario MAX CN analyser (measured % C) and Loss on Ignition (calculated % C). The results showed that natural woodland had higher (9.32%) C than the tree treatment (4.91%), and both had significantly higher C than the grass (1.12%) and the eroded (0.76%) treatments (p < 0.0001). The amount of C in the grass and the eroded treatments were not statistically different (p > 0.0566). Notably, the grass treatment had carbon below the minimum expected level of 1.5% in Icelandic Andosol under vegetation. The natural woodland and the tree treatment had fine soil texture than the grass and eroded plots. Results suggest that where land has been properly restored or kept in natural condition, soil properties improve significantly especially when trees are part of the restored vegetation. The natural woodland had possibly not lost the old carbon-rich soil, as was the case with the tree, grass and eroded plots hence more time for development of various soil properties. Moreover, more litter deposits in natural woodlands and partly in the tree treatments might have contributed to higher carbon than in the grass and eroded treatments. Furthermore clay content variations (natural woodlands and the tree treatments had finer soil texture) might also be responsible for C limitations in the grass and the eroded treatments. Therefore, more restoration efforts are encouraged. The results also showed that LOI is a good method for C estimation but not very accurate estimator of soil organic carbon unless equations are developed with respect to known carbon content of particular soil type.
利用植被恢复来复垦退化土地是将碳固存到土壤中的一种方式。在本研究中，对冰岛西南部（哈夫纳梅拉尔）树木和草地植被恢复后的土壤碳含量状况进行了评估。天然林地和侵蚀地块作为对照地块纳入评估，共形成四种处理。对土壤样本进行了容重、碳含量和土壤质地分析。使用元素分析仪（测量的碳百分比）和灼烧减量（计算的碳百分比）分析总碳百分比（C）。结果表明，天然林地的碳含量（9.32%）高于树木处理（4.91%），且二者的碳含量均显著高于草地（1.12%）和侵蚀地块（0.76%）处理（p < 0.0001）。草地和侵蚀地块处理中的碳含量在统计学上没有差异（p > 0.0566）。值得注意的是，草地处理的碳含量低于冰岛植被下安山土预期的最低水平1.5%。天然林地和树木处理的土壤质地比草地和侵蚀地块更细。结果表明，在土地得到妥善恢复或保持自然状态的地方，土壤性质会显著改善，特别是当树木是恢复植被的一部分时。天然林地可能没有像树木、草地和侵蚀地块那样失去富含碳的旧土壤，因此有更多时间发展各种土壤性质。此外，天然林地以及部分树木处理中有更多的凋落物沉积，这可能导致其碳含量高于草地和侵蚀地块处理。此外，粘土含量的差异（天然林地和树木处理的土壤质地更细）也可能是草地和侵蚀地块处理中碳含量受限的原因。因此，鼓励加大恢复力度。结果还表明，灼烧减量是一种估算碳的好方法，但除非针对特定土壤类型的已知碳含量建立方程，否则它不是土壤有机碳的非常准确的估算器。
