Purpose

Sustainable management of riparian zone soils is required to ensure the health of natural ecosystems and maintenance of soil nitrogen (N) pools and soil N cycling. However, the effect of revegetation type and age on soil N pools remains poorly understood.

Materials and methods

This study compiled data from published articles to understand the effects of revegetation types and age on soil total N (TN) and soil inorganic N (NH₄⁺-N, and NO₃⁻-N) using a meta-analysis. We extracted 645 observations from 52 published scientific articles.

Results and discussion

The revegetation of riparian zones led to a significant increase of soil TN (mean effect size: 11.5%; 95% CI: 3.1% and 20.6%). Woodland increased soil TN significantly by 14.0%, which was associated with the presence of N fixing species and high litter inputs. Soil NH₄⁺-N concentration significantly increased (mean effect size: 20.1%; 95% CI: 15.1% and 25.4%), whereas a significant decrease in soil NO₃⁻-N (mean effect size: − 21.5%; 95% CI: − 15.0% and − 27.5%) was observed. Of the revegetation types considered in this paper, NO₃⁻-N concentration in soil followed the order: grassland < shrubland < woodland, suggesting that woodland might be more efficient in soil NO₃⁻-N retention than grassland. The high plant N uptake and accelerated NO₃⁻-N leaching in grassland could be related to the decreased soil NO₃⁻-N in grassland compared with other revegetation types. Revegetation significantly decreased soil moisture by (mean effect size: − 7.9%; 95% CI: − 3.3% and − 12.2%) compared with the control, which might be associated with the selection of exotic species as dominant vegetation in the riparian zone. Soil TN increased in revegetation ages between 10 and 40 years following revegetation and was related to increased soil organic carbon inputs within those ages following the establishment.

Conclusions

This study provides insight into influence of different vegetation types and age on soil N pools and soil moisture. This study also highlights the importance of revegetation in riparian zones to increase soil TN.

中文翻译：

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全球荟萃分析显示，河岸带植被恢复后土壤氮库增加

目的

需要对河岸带土壤进行可持续管理，以确保自然生态系统的健康并维持土壤氮（N）库和土壤氮循环。然而，植被类型和年龄对土壤氮库的影响仍然知之甚少。

材料和方法

这项研究汇总了已发表文章的数据，以通过荟萃分析了解植被类型和年龄对土壤总氮（TN）和土壤无机氮（NH ₄ ⁺ -N和NO ₃ ^-- N）的影响。我们从52篇发表的科学文章中提取了645个观测值。

结果与讨论

河岸带的植被恢复导致土壤总氮显着增加（平均效应大小：11.5％； 95％CI：3.1％和20.6％）。林地显着增加了土壤总氮（TN）14.0％，这与固氮菌种和大量凋落物的存在有关。土壤NH ₄ ⁺ -N浓度显着增加（平均影响大小：-21.5％； 95％CI：15.1％和25.4％），而土壤NO ₃ ^-- N显着降低（平均影响大小：-21.5％； 95％） CI：-15.0％和-27.5％。在本文所考虑的植被的类型，NO ₃ ^- -N土壤浓度依次为：草地<灌木<林地，表明林地可能在土壤NO更有效的₃ ^--N保留率比草原高。与其他植被类型相比，草原上较高的植物N吸收和NO ₃ ^-- N淋溶加速可能与草原土壤NO ₃ ^-- N减少有关。与对照相比，植被明显减少了土壤水分（平均影响大小：-7.9％； 95％CI：-3.3％和-12.2％），这可能与选择外来物种作为河岸带的优势植被有关。在植被恢复后的10至40年之间，植被恢复期间的土壤TN升高，并且与建立后的那些年龄内土壤有机碳输入量的增加有关。

结论

这项研究提供了洞察不同植被类型和年龄对土壤氮库和土壤水分的影响。这项研究还强调了河岸地区的植被恢复对增加土壤总氮的重要性。