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在2010年5月—2011年4月和2011年5月—2012年4月2个培养周期内,采用原状土柱野外控制试验,利用海拔梯度变化研究了温度增加对川西高山森林土壤溶解性有机碳(DOC)和有机氮(DON)动态的影响.结果表明:经模拟增温处理(降低海拔)的土壤有机层和矿质土壤层DOC和DON含量在2个连续培养周期内的各关键时期均呈现明显的动态变化.海拔3300和3000 m样地比海拔3600 m样地土层DOC含量分别增加6.8和26.6 mg·kg~(-1).海拔3600、3300和3000 m样地土层DOC含量均在第1个培养周期的生长季末最高,分别为408.0、317.9和448.2 mg·kg~(-1),在第2个培养周期的生长季节中期最低,分别为33.1、32.4和36.5 mg·kg~(-1).与海拔3600 m样地相比,海拔3300和3000 m样地土层DON含量分别增加2.3和30.4 mg·kg~(-1).除海拔3000 m样地以外,海拔3600和3300 m样地土层DON含量在第1个培养周期内的生长季节中期最高,分别为65.9和64.6 mg·kg~(-1),在第1个培养周期内的融化期最低,分别为31.9和37.1 mg·kg~(-1).模拟增温处理增加了样地内土壤有机层DOC和DON含量,降低了矿质土壤层DOC含量、土壤有机层及矿质土壤层DOC/DON值.土壤有机层DOC/DON值与DOC含量呈显著正相关,与DON含量呈显著负相关;矿质土壤层DOC/DON值与DOC含量呈显著负相关,与DON含量呈显著正相关.未来全球气候变暖可能通过影响高寒森林土壤温度和冻融循环格局,增加整个土层DOC和DON含量,进而影响高寒森林土壤碳、氮循环过程.
In the May 2010-April 2011 and May 2011-April 2012 incubation period, the open soil column control experiment was used to study the effects of temperature increase on the soil dissolved organic (DOC) and organic nitrogen (DON). The results showed that the contents of DOC and DON in soil organic layer and mineral soil layer under simulated warming (elevation reduction) The DOC content in the soil samples of 3300 and 3000 m above sea level increased by 6.8 and 26.6 mg · kg -1 than that of 3600 m above sea level respectively.The DOC content Which were the highest at the end of growing season of the first cultivating period, which were 408.0, 317.9 and 448.2 mg · kg -1, respectively, the lowest in the second growing season, which were 33.1, 32.4 and 36.5 mg · kg -1 .The soil DON contents at the elevation of 3300 and 3000 m increased by 2.3 and 30.4 mg · kg -1 compared with the elevation of 3600 m respectively.Except for the elevation of 3000 m, The contents of DON in the soil samples from the 3600 and 3300 m plots were the highest in the middle growing season in the first incubation period, which were 65.9 and 64.6 mg · kg -1, The thawing period was the lowest in the first incubation period, at 31.9 and 37.1 mg · kg -1, respectively. Simulated warming increased DOC and DON content in the soil organic layer and decreased the DOC content in the mineral soil layer. Soil Organic layer and mineral soil layer DOC / DON value was positively correlated with DOC content and negatively correlated with DON content; DOC / DON value of mineral soil layer was negatively correlated with DOC content, and DON content was significantly positive.Global warming in the future may affect the alpine forest soil temperature and freeze-thaw cycle pattern, increasing the DOC and DON content of soil, and then affect the alpine forest soil carbon and nitrogen cycle.