不同利用方式下草地CH4、CO2及N2O通量研究

STUDY ON CH4, CO2 AND N2O FLUXES OF GRASSLAND UNDER DIFFERENT UTILIZATION

关键词:  天然草地  人工草地  温室气体  影响因子

Key words:  natural grasslands  artificial grasslands  greenhouse gas  influencing factor

摘要:

目的 在全球气候变化背景下，研究天然草地和人工草地的温室气体通量以及与部分环境因子的相关关系，进而明确不同草地对温室气体通量的影响情况，为当地相关部门合理开发利用草地提供理论依据，推进草业绿色发展、高质量发展。方法 文章以内蒙古自治区的阿鲁科尔沁旗选取退化的天然牧草地、混播型放牧人工草地以及刈割型人工牧草地为研究对象，利用目前较为普遍的箱法进行了野外实验，对比分析不同草地利用类型的主要温室气体CO₂、CH₄和N₂O的通量变化情况，并进一步探讨了温室气体与土壤含 水量、箱内温度、地表温度以及其他土壤养分指标的相关性。结果 （1）不同利用方式下草地的CO₂通量在整个生长季均表现为排放，其中刈割人工草地的CO₂排放量为67.00±9.15 mg/（m²·h），显著高于放牧人工草地35.50±5.37 mg/（m²·h）和天然草地30.17±4.57 mg/（m²·h）（P<0.05），且CO₂的通量与土壤含水量和温度呈正相关关系（P<0.05），此外还与土壤全碳、全氮及有机碳含量呈极显著负相关关系（P<0.01）；（2）3种草地类型的CH₄通量在整个生长季均表现为吸收，放牧人工草地的CH₄吸收量相对较低，为-19.10±4.24 μg/（m²·h），CH₄通量与土壤含水量和温度均未表现出显著的相关关系；（3）不同草地N₂O通量在整个生长季均表现为排放，退化的天然草地的N₂O通量在整个生长季表现最低，为11.62±5.96 μg/（m²·h），刈割人工草地的N₂O通量与箱内温度和土壤温度呈显著正相关关系（P<0.05）。结论 可见人工草地的建立以及补播放牧等行为由于土壤含水量、箱内温度、地表温度以及土壤养分指标受到影响，进而不同程度上影响温室气体通量变化，人工草地的建立及放牧补播人工灌溉等人为干预会不同程度上增加CO₂和N₂O的排放量，此外，放牧会降低草地CH₄汇的功能。

Abstract:

In the context of global climate change, this paper aims to study the greenhouse gas fluxes of natural grassland and artificial grassland and the correlation with some environmental factors, and clarify the impact of different grasslands on greenhouse gas fluxes, so as to provide a theoretical basis for the rational development and utilization of grassland by relevant local departments, and promote the green development and high-quality development of grass industry.This study selected degraded natural grassland, mixed grazed artificial grassland, and mown artificial grassland through Ar Horqin Banner, Inner Mongolia Autonomous Region.In addition, it carried outfield experiments, andused the more common box method to compare and analyze the flux changes of the main greenhouse gases CO₂, CH₄, and N₂O for different grassland utilization types, and further it explored the correlation between greenhouse gases and soil moisture content, box temperature, surface temperature and other soil nutrient indicators.The results were showed as follows. (1) The CO₂ flux of grassland under different utilization methods was shown as emissions throughout the growing season. The CO₂ emissions from mown artificial grassland were 67.00±9.15 mg/(m²·h), which was significantly higher than that of grazed artificial grassland 35.50±5.37 mg/(m²·h) and natural grassland 30.17±4.57 mg/(m²·h) (P<0.05), and the flux of CO₂ was positively correlated with soil water content and temperature (P<0.05). In addition, there was a very significant negative correlation with soil total carbon, total nitrogen and organic carbon content (P<0.01). (2) CH4 flux of the three grassland types were absorbed throughout the growth season,the CH₄ uptake of grazed artificial grassland was relatively low -19.10±4.24 μg/(m²·h). CH4 flux had no significant correlation with soil water content and temperature. (3)The N₂O fluxes of different grasslands were emissions during the entire growing season. The N₂O fluxes of degraded natural grasslands had the lowest performance in the entire growing season, which was 11.62±5.96 μg/(m²·h). The N₂O fluxes of mowing artificial grassland were the lowest. The amount was significantly positively correlated with the temperature in the box and the soil temperature (P<0.05). In conclude,it can be seen that the establishment of artificial grassland and supplementary grazing and other behaviors are affected by soil water content, box temperature, surface temperature and soil nutrient indicators, which in turn affects greenhouse gas flux changes to varying degrees. And the establishment of artificial grassland and artificial irrigation such as grazing supplementary sowing will increase CO₂ and N₂O emissions to varying degrees. In addition, grazing will reduce the function of grassland CH₄ sinks.