YO-JIN SHIAUChang, Ed-HaunEd-HaunChangTian, GuanglongGuanglongTianChen, Tsai-HueiTsai-HueiChenChiu, Chih-YuChih-YuChiu2021-02-042021-02-042020https://www.scopus.com/record/display.uri?eid=2-s2.0-85091405539&origin=recordpagehttps://scholars.lib.ntu.edu.tw/handle/123456789/548333Reforestation is an important step toward recovering soil quality and wildlife habitats that are degraded due to deforestation. However, little is known about how soil C and N compositions in subtropical forests evolve after decades of reforestation. This study comprehensively evaluated the differences in soil C and N fractions in 40- and 80-year-old secondary (reforested) coniferous forests and a natural broadleaf forest. Although reforestation with coniferous plants appeared to increase soil organic matter and labile C levels, the ratio of soil labile C to total organic C was lower in the reforested coniferous forests than the natural broadleaf one. The trend in the labile N to total N ratio as coniferous reforestation progresses follows that of C. Furthermore, the percentage of recalcitrant C as total soil organic C was higher in the reforested coniferous forests than the natural broadleaf one. This feature of C composition in reforested coniferous forest causes environmental stress to microbes (as indicated by a high metabolic quotient) in the forest, even several decades after reforestation of a former broadleaf forest site. Results from this study demonstrate that it takes a very long time for reforestation with coniferous vegetation to restore the soil chemical properties of the previous natural forest.acid-hydrolyzable Cbroadleaf forestconiferous foresthot water-extractable C and NKCl-extractable C and Nreforestation[SDGs]SDG2[SDGs]SDG13[SDGs]SDG14[SDGs]SDG15journal article10.1029/2019JG0055982-s2.0-85091405539WOS:000576409700004