Mao Liang, Miao Yugu, Ge Yiru, Wei Shaochong, Yang Xuanyi, Li Shijie, Si Li, Gou Yu-Ping, Quandahor Peter
Gansu Agricultural University, Lanzhou, 730070, People's Republic of China.
Forestry and Grassland Bureau of Lintao County, Dingxi, 730075, Gansu Province, People's Republic of China.
Sci Rep. 2024 Jul 13;14(1):16194. doi: 10.1038/s41598-024-66408-z.
In the area of "returning farmland to forest" on the Loess Plateau in China, it is difficult to cultivate artificially planted trees into forests. In the current study, abandoned cultivated land after 10 years of natural restoration served as controls (CK), while the treatments included afforestation periods of 2, 4, 6, 8, and 10 years. Soil samples were collected from various depths: 0-20, 20-40, 40-60, 60-80, to 80-100 cm. The findings revealed that with increasing years of artificial afforestation, soil pH gradually increased, and soil moisture content rose in the 0-20 cm layer while declining in deeper layers (20-100 cm) in the Maxian Mountain region of the Loess Plateau. Moreover, the total carbon, nitrogen, phosphorus, and potassium content initially increased and then decreased with the duration of artificial afforestation, reaching peak values after 8 years. Contents of organic matter, ammonium nitrogen, nitrate nitrogen, available phosphorus, and available potassium in the same soil layer increased with each year of afforestation. However, upon reaching 10 years of artificial afforestation, the effective nutrient content in the 60-80 and 80-100 cm soil layers exhibited a decrease. The values of Integrated Fertility Index (IFI) in different afforestation years were ranked as follows: 8 years > 6 years > 10 years > 4 years > 2 year, but all of them were significantly smaller than those of natural restoration plot CK (P < 0.05). Overall, soil fertility in the Maxian Mountain area of the Loess Plateau increases with each additional year of artificial afforestation. However, when the artificial afforestation period is 10 years, soil fertility decreases and marking a shift from enhancement to decline beyond this duration.
在中国黄土高原“退耕还林”区域，人工造林成林难度较大。在本研究中，选取自然恢复10年后的弃耕地作为对照（CK），处理组包括造林2年、4年、6年、8年和10年的林地。从0 - 20、20 - 40、40 - 60、60 - 80至80 - 100 cm不同深度采集土壤样本。结果表明，随着人工造林年限增加，黄土高原马衔山地区土壤pH值逐渐升高，0 - 20 cm土层土壤含水量增加，而深层（20 - 100 cm）土壤含水量下降。此外，土壤总碳、氮、磷、钾含量随人工造林年限先增加后减少，8年后达到峰值。同一土层的有机质、铵态氮、硝态氮、有效磷和有效钾含量随造林年份逐年增加。然而，人工造林10年后，60 - 80和80 - 100 cm土层有效养分含量下降。不同造林年份的综合肥力指数（IFI）排序为：8年＞6年＞10年＞4年＞2年，但均显著低于自然恢复对照地CK（P＜0.05）。总体而言，黄土高原马衔山地区土壤肥力随人工造林年限增加而提高。然而，当人工造林年限达到10年时，土壤肥力下降，并标志着超过此年限后从提高转为下降。
