Appropriate agroforestry practices might contribute to carbon sequestration and cope with climate change by modulating ecosystem services. It is known that land use change might affect soil-atmosphere carbon dioxide (CO₂) effluxes of agro-silvopastoral systems. However, little information is available at single microenvironment level. Across four years, fortnightly measurements of soil respiration were carried out at different microenvironment (beneath tree cover vs open areas) and land use (native understorey vs its conversion into improved pasture) within a high-density evergreen cork oak forest of Sardinia (Italy). We also monitored aboveground dry matter yields and soil carbon stocks. Measurements revealed that the two investigated microenvironments widely differed for the amounts of photosynthetically active radiation and microclimatic traits such as soil water content, air humidity, soil and air temperature. High seasonal and inter-annual variability in soil respiration rates was recorded (range 0.3–12.6 CO₂ μmol m⁻² s^-1) and the peak values were reached in the summer of the third year in the improved pasture beneath tree cover. The conversion of the native understorey into improved pasture beneath cork oak increased significantly the annual cumulative soil respiration for three consecutive years, reaching values of about 71, 36 and 100 t CO₂ ha⁻¹ yr⁻¹, which were from 38 to 88 % higher than the remaining treatments. On average, heterotrophic component represented from 68–76% of soil respiration. An extreme drought event, which was emblematic of a climate change context, was experienced in the second year. It countered the increase in the heterotrophic component of soil respiration and minimized up to 20-fold the forage on offer from pasture swards. Based on measured CO₂ effluxes, the study demonstrated that the effects of the land use change at the microenvironment beneath tree cover were substantially unbalanced in terms of soil organic carbon stocks. Therefore, results suggest avoiding the soil mechanical disturbance beneath cork oak in the investigated ecosystem to reduce anthropogenic carbon fluxes to the atmosphere.

适当的农林业实践可能通过调节生态系统服务来促进碳固存和应对气候变化。众所周知，土地利用变化可能会影响土壤-大气二氧化碳（CO ₂) 农林牧系统的流出。然而，在单个微环境级别上可用的信息很少。四年间，在撒丁岛（意大利）的高密度常绿软木橡树林内，每两周对不同的微环境（树木覆盖下与开放区域）和土地利用（原生林下与转化为改良牧场）进行土壤呼吸测量. 我们还监测了地上干物质产量和土壤碳储量。测量结果表明，这两个研究的微环境在光合有效辐射量和微气候特征（如土壤含水量、空气湿度、土壤和气温）方面存在很大差异。记录了土壤呼吸速率的高季节性和年际变化（范围 0.3–12.6 CO ₂ μmol m^-2 s ^-1 ) 并且在树木覆盖下的改良牧场的第三年夏季达到峰值。在软木橡树下将原生下层转化为改良牧场，连续三年显着增加了年度累积土壤呼吸，达到约 71、36 和 100 t CO ₂ ha ^-1 yr ^{-1 的值}，比其余处理高 38% 至 88%。平均而言，异养成分占土壤呼吸的 68-76%。第二年发生了象征气候变化背景的极端干旱事件。它抵消了土壤呼吸异养成分的增加，并将牧场提供的草料减少了 20 倍。基于测量的 CO ₂流出，该研究表明，土地利用变化对树木覆盖下微环境的影响在土壤有机碳储量方面基本上不平衡。因此，结果表明在所调查的生态系统中避免软木橡树下的土壤机械干扰，以减少人为碳排放到大气中。