亚热带不同林龄次生林与杉木林土壤氮淋溶损失特征

为分析不同林龄亚热带常绿阔叶次生林和杉木(Cunninghamia lanceolata)种植对土壤氮淋溶的影响,采用土柱微宇宙原位培养,分别比较9年生和45年生次生林(以米槠Castanopsis carlesii为建群种)之间、米槠和杉木人工林(均为9年生)之间的土壤总氮、硝态氮和铵态氮浓度及通量。结果表明：(1)4种类型森林土壤总氮和硝态氮浓度均表现为45年生次生林>9年生次生林>杉木人工林>米槠人工林;铵态氮浓度则为45年生次生林>杉木人工林>9年生次生林>米槠人工林。(2)4种类型森林土壤总氮和硝态氮的淋溶通量在整个试验期表现为9年生次生林>45年生次生林>杉木人工林>米槠人工林;5—8月4种类型森林土壤氨态氮淋溶通量差异较大,但大体上表现为杉木人工林>45年生次生林>9年生次生林>米槠人工林。(3)9年生和45年生次生林、米槠人工林、杉木人工林土壤总氮年淋溶量分别为14.24,13.27,7.26,10.97 [g/(m²·a)],硝态氮年淋溶量分别为10.88,9.97,5.35...

Soil Nitrogen Leaching Loss Characteristics of Subtropical Secondary Forests of Different Ages and Cunninghamia Lanceolata Plantations

To assess whether soil nitrogen leaching would be affected by the planting subtropical evergreen broad-leaved secondary forests of different ages and Chinese fir (Cunninghamia lanceolata) plantations, soil column microcosm in situ culture experiment was used to compare the soil total nitrogen, nitrate and ammonium concentrations and fluxes between 9-year-old and 45-year-old secondary forests (with Castanopsis carlesii as the dominant tree species), and between C. carlesii and C. lanceolata plantations (both 9-year-old). The results showed that: (1) The concentrations of total nitrogen and nitrate in the four forest soils showed a general pattern of 45-year-old secondary forest > 9-year-old secondary forest > C. lanceolata plantation > C. carlesii plantation. The concentration of ammonium nitrogen was 45 years old secondary forest > C. lanceolata plantation > 9 years old secondary forest > C.carlesii plantation. (2) The fluxes of total nitrogen and nitrate of the four forest types in soil leaching solutions were as follows: 9-year-old secondary forest > 45-year-old secondary forest > C. lanceolata plantation > C. carlesii plantation, and soil ammonium leaching fluxes varied significantly among the four forest types between may and August, showing a order of C. lanceolata plantation > 45-year-old secondary forest > 9-year-old secondary forest > C. carlesii plantation. (3) The annual leaching fluxes of total nitrogen were 14.24, 13.27, 7.26 and 10.97 g/(m²·a), the nitrate leaching fluxes were 10.88, 9.97, 5.35 and 8.44, and the ammonium leaching fluxes were 1.97, 2.18, 1.59 and 2.26 g/(m²·a), in the 9-year-old and 45-year-old secondary forests, C. carlesii plantation and C. lanceolata plantation, respectively. In summary, the leaching loss of soil total nitrogen and nitrate decreased along the growth of subtropical evergreen broad-leaved secondary forest age, but the plantations of C. lanceolata accelerate nitrogen leaching loss from soils relative to the native tree species.