| 防护林建设过程中土壤微生物养分限制与有机碳组分之间的关系 |
| 摘要点击 632 全文点击 94 投稿时间：2023-04-17 修订日期：2023-06-28 |
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| 中文关键词 防护林建设 土壤有机碳（SOC） 颗粒态有机碳（POC） 矿物结合态有机碳（MAOC） 土壤胞外酶活性 养分限制 |
| 英文关键词 shelterbelt construction soil organic carbon（SOC） particulate oganic carbon（POC） mineral associated organic carbon（MAOC） soil extracellular enzyme activities nutrient limitation |
| 作者 | 单位 | E-mail | | 徐凤璟 | 西北农林科技大学资源环境学院, 农业农村部西北植物营养与农业环境重点实验室, 农业农村部西北旱地农业绿色低碳重点实验室, 杨凌 712100 | xufengjing@nwafu.edu.cn | | 黄懿梅 | 西北农林科技大学资源环境学院, 农业农村部西北植物营养与农业环境重点实验室, 农业农村部西北旱地农业绿色低碳重点实验室, 杨凌 712100 | ymhuang1971@nwsuaf.edu.cn | | 黄倩 | 西北农林科技大学资源环境学院, 农业农村部西北植物营养与农业环境重点实验室, 农业农村部西北旱地农业绿色低碳重点实验室, 杨凌 712100 | | | 申继凯 | 西北农林科技大学资源环境学院, 农业农村部西北植物营养与农业环境重点实验室, 农业农村部西北旱地农业绿色低碳重点实验室, 杨凌 712100 | |
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| 中文摘要 |
| 微生物主要通过“体外修饰”和“体内周转”途径影响土壤颗粒态有机碳（POC）和矿物结合态有机碳（MAOC）的累积,而不同的植物输入引起的微生物养分限制对两种土壤有机碳（SOC）组分累积的影响机制尚不清楚.因此,以陕西省米脂县的撂荒地为对照（CK）,测定人工林建设的第3、13、20和37 a的0~5、5~10和10~20 cm土层中SOC、POC和MAOC含量及用于计算养分限制的土壤胞外酶活性,探讨防护林建设过程中SOC积累的微生物养分限制机制.结果表明：①ω（SOC）、ω（POC）和ω（MAOC）分别3.14~8.35、0.44~1.87和1.99~6.72 g·kg-1；各组分有机碳含量在林地建设第3 a时均显著低于CK（P<0.05）,且随防护林建设先增加后降低：0~5 cm和5~10 cm中SOC和MAOC含量在第20 a达到最大,但总体低于CK；10~20 cm中二者在第13 a达到最大且高于CK；0~5 cm和5~10 cm中ω（POC）在第37 a达到最大,10~20 cm中在第13 a达到最大.②0~5 cm中β-葡萄糖苷酶活性在第20 a时最高,其余土层在第13 a最高,但均在第37 a降至最低；0~5 cm中亮氨酸氨基肽酶和N-乙酰基氨基葡萄糖苷酶活性随防护林建设呈增加趋势,第37 a时显著高于CK（P<0.05）；碱性磷酸酶活性在第3 a时显著低于CK（P<0.05）,第20 a时0~5 cm和5~10 cm中其活性最高,10~20 cm中为最低.③第3 a酶化学计量比的向量角度（VA）和长度（VL）显著高于CK（P<0.05）,即防护林建设加剧了微生物C、N限制；在防护林建设过程中,N限制减弱,而C限制仅在第37 a时有所缓解.④结构方程模型显示,第3 a微生物C限制的增强,导致POC含量降低和MAOC含量增加,微生物将主要以“体内周转”积累有机碳；随着微生物N限制的缓解,通过“体内周转”形成的MAOC含量将会增加.因此,长期的防护林建设利于植物源有机碳累积,且以固氮植物造林将有助于促进稳定的SOC组分增加,提升植被固碳效率. |
| 英文摘要 |
| Microorganisms affect the accumulation of soil particulate organic carbon （POC） and mineral bound organic carbon （MAOC） mainly through the “ex vivo modification” and “in vivo turnover” pathways, whereas the mechanism by which microbial nutrient limitation due to different plant inputs affects the accumulation of both soil organic carbon （SOC） fractions is unclear. The mechanism of microbial nutrient limitation caused by different plant inputs on the accumulation of the two soil organic carbon （SOC） fractions also remains unclear. Therefore, in this study, the SOC, POC, and MAOC contents and the extracellular enzyme activities used to calculate nutrient limitation were measured in the 0-5, 5-10, and 10-20 cm soil layers during the 3rd, 13th, 20th, and 37th year of shelterbelt construction, using the abandoned land in Mizhi County, Shaanxi Province, as a control （CK）, to explore the microbial nutrient limitation mechanism of SOC accumulation during the construction of protection forests. The results showed that： ω（SOC）, ω（POC）, and ω（MAOC） ranged from 3.14-8.35, 0.44-1.87, and 1.99-6.72 g·kg-1, respectively. The SOC content of each component was significantly lower than that of CK （P<0.05） in the 3rd year of stand construction, increasing and then decreasing with stand construction： ① SOC and MAOC contents reached their maximum in the 0-5 and 5-10 cm soil layers in the 20th year but were lower than those in CK. In the 10-20 cm soil layer, they reached a maximum in the 13th year and were higher than that in CK. ω（POC） reached its maximum in the 37th year in the 0-5 and 5-10 cm soil layers and in the 13th year in the 10-20 cm soil layer. ② The β-glucosidase activity was highest in the 20th year in the 0-5 cm soil layer and highest in the 13th year in the rest of the soil layers； however, all decreased to the lowest activity in the 37th year. The activities of leucine aminopeptidase and N-acetylaminoglucosidase in the 0-5 cm soil layer tended to increase with the construction of the shelterbelt and were significantly higher than those of CK in the 37th year （P<0.05）. Alkaline phosphatase activity was significantly lower than that of CK in the 3rd year （P<0.05） and was highest in the 0-5 and 5-10 cm soil layers in the 20th year and lowest in 10-20 cm. ③ The vector angle （VA） and vector length （VL） of the enzyme stoichiometry ratio in the 3rd year were significantly higher than those of CK （P<0.05）, i.e., microbial C and N limitation was exacerbated by shelterbelt construction. During shelterbelt construction, N limitation weakened, whereas C limitation was only alleviated in the 37th year. ④ The structural equation model showed that the increase in microbial C limitation in the 3rd year led to a decrease in POC content and an increase in MAOC content and that microorganisms would accumulate organic carbon mainly via “in vivo turnover.” As microbial N limitation was alleviated, the MAOC content formed via “in vivo turnover” would increase. Therefore, long-term shelterbelt construction is conducive to the accumulation of plant-derived organic carbon, and afforestation with nitrogen-fixing plants will help to promote the increase in stable SOC fractions and enhance vegetation carbon sequestration efficiency. |
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