This study aimed to quantify the dynamics of soil CO₂ fluxes in two silvopastoral systems based on Leucaena leucocephala, one associated with Panicum maximum (L + P) and another with Cynodon plectostachyus (L + C). We measured CO₂ fluxes fortnightly during the dry and rainy seasons in the morning and the afternoon, with an infrared gas analyzer. Simultaneously, we measured soil temperature, soil moisture, ambient temperature, and relative humidity. Soil CO₂ fluxes ranged from 6.0 ± 0.14 to 6.1 ± 0.12 µmol CO₂/m²/s but no statistical differences were observed between systems. Soil CO₂ flux in the L + P was 12.5% higher in the rainy season compared with the dry season but the season did not affect the fluxes in L + C. Regarding the diurnal variation, CO₂ fluxes were 17.6%–34.8% higher in the morning compared with afternoon measurements. Soil moisture and temperature were higher in L + C, but the ambient temperature and relative humidity showed no statistical differences between systems. In both systems, soil temperature was greater in the afternoon, while the soil moisture and relative humidity were greater in the morning. The diurnal variation of soil CO₂ fluxes in silvopastoral systems correlated positively with soil temperature and ambient temperature, but negatively with relative humidity. We concluded that soil CO₂ fluxes did not vary between silvopastoral systems but respond differently to the seasons. The results have important implications on the establishment and management of Leucaena‐based silvopastoral systems for the mitigation of soil CO₂ fluxes from extensive livestock production lands.

中文翻译：

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热带牧草系统土壤CO2通量的日变化和季节变化

这项研究旨在量化两种基于银合欢的林牧牧业系统中土壤CO ₂通量的动态，一个与潘尼库姆（L + P）相关，另一个与Cynodon plectostachyus（L + C）相关。我们使用红外气体分析仪在干旱和雨季的前两周每两周测量一次CO ₂通量。同时，我们测量了土壤温度，土壤湿度，环境温度和相对湿度。土壤CO ₂通量范围为6.0±0.14至6.1±0.12 µmol CO ₂ / m ² / s，但系统之间未观察到统计学差异。土壤CO ₂与雨季相比，雨季的L + P通量增加了12.5％，但该季节并未影响L + C的通量。关于日变化，早晨的CO ₂通量增加了17.6％– 34.8％。与下午的测量结果相比。L + C中的土壤湿度和温度较高，但是环境温度和相对湿度在系统之间没有统计学差异。在这两个系统中，下午的土壤温度较高，而早上的土壤湿度和相对湿度较高。牧草系统中土壤CO ₂通量的日变化与土壤温度和环境温度呈正相关，而与相对湿度呈负相关。我们得出结论，土壤CO ₂牧牧系统之间的通量没有变化，但是对季节的反应不同。这些结果对基于Leucaena的林牧系统的建立和管理对减轻广泛的畜牧生产地的土壤CO ₂通量具有重要意义。