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采用室内培养方法研究了温度(5、15、25和35℃)和湿度(20、40、60和80%田间持水量(FWC))对华西雨屏区柳杉(Cryptomeria fortunei)人工林表层(0~20 cm)土壤氮素矿化的影响,并探讨了温度和湿度与土壤氮素矿化的关系及土壤氮素矿化的最适温度和湿度。结果表明:在30 d的培养过程中温度和湿度均对华西雨屏区柳杉林土壤氮矿化有显著影响(p<0.05);相同水分条件下,土壤净氨化速率和氮净矿化速率均随温度的升高而增加;净硝化速率先随温度的升高而增加,在25℃时达到最大值,之后又随温度的升高而降低。相同温度条件下,土壤净氨化速率、净硝化速率和氮净矿化速率均先随水分含量的升高而增加,在60%FWC时达到最大值,之后又随水分含量的升高而降低。在温度和湿度16个交互处理中,35℃和60%FWC条件下土壤净氨化速率和氮净矿化速率最高,在25℃和60%FWC条件下土壤净硝化速率最高;在5℃和20%FWC条件下土壤净氨化速率、净硝化速率和氮净矿化速率最低。土壤氮净矿化的最适温度和湿度分别为32.9℃和64.1%FWC。研究区各土壤水分含量(x1)和温度(x2)条件下的氮净矿化速率(y7)可用关系式y7=-0.5374+0.05001x2+0.04374x1-0.0009228x22-0.0003749x12+0.000215x1·x2进行估算。土壤氮矿化Q10值在5~35℃内随温度的升高而降低,氮净矿化在5~15℃内对温度敏感性最高。氮净矿化作用产生的无机氮中铵态氮占77.6~87.6%,说明该区柳杉人工林表层土壤氮矿化形成的铵态氮只有少部分转化成了硝态氮,这有利于减少研究区多雨条件下矿质氮的淋失。
The effects of temperature (5, 15, 25 and 35 ℃) and humidity (20, 40, 60 and 80% field capacity) on the surface layer of Cryptomeria fortunei plantations 0 ~ 20 cm) soil nitrogen mineralization, and discussed the relationship between temperature and humidity and soil nitrogen mineralization and soil nitrogen mineralization optimum temperature and humidity. The results showed that temperature and humidity all had significant effects on soil nitrogen mineralization in the Cryptomeria fortunei forest in the rainy area of Huaxi (p <0.05) during the 30 d incubation period. Under the same water conditions, the soil net ammonification rate and nitrogen mineralization rate Both increased with the increase of temperature. The net nitrification rate increased with the increase of temperature and reached the maximum at 25 ℃, then decreased with the increase of temperature. Under the same temperature conditions, the net net ammonification rate, net nitrification rate and net nitrogen mineralization rate both increased with the increase of water content, reached the maximum value at 60% FWC, and then decreased with the increase of water content . The soil net ammonification rate and nitrogen mineralization rate were the highest under the conditions of 35 ℃ and 60% FWC, and the highest net soil nitrification rate was at 25 ℃ and 60% FWC under 16 reciprocal temperature and humidity conditions. At 5 ℃ and Soil net ammonification rate, net nitrification rate and net nitrogen mineralization rate were the lowest under 20% FWC. The optimum temperature and humidity of soil nitrogen net mineralization were 32.9 ℃ and 64.1% FWC, respectively. The net nitrogen mineralization rate (y7) at each soil moisture content (x1) and temperature (x2) in the study area can be calculated using the relationship y7 = -0.5374 + 0.05001x2 + 0.04374x1-0.0009228x22-0.0003749x12 + 0.000215x1 · x2 Estimated. Soil nitrogen mineralization Q10 value decreases with increasing temperature within 5 ~ 35 ℃, and nitrogen net mineralization has the highest temperature sensitivity at 5 ~ 15 ℃. The amount of ammonium nitrogen in inorganic nitrogen produced by nitrogen net mineralization accounts for 77.6-87.6%, indicating that only a small part of the ammonium nitrogen formed by nitrogen mineralization in the surface soil of Cryptomeria fortunei plantation is converted to nitrate nitrogen, which is beneficial to reduce Leaching of mineral nitrogen under rainy conditions in the study area.