Pasture enclosures play an important role in rehabilitating the degraded soils and vegetation, and may also influence the emission of key greenhouse gasses (GHGs) from the soil. However, no study in East Africa and in Kenya has conducted direct measurements of GHG fluxes following the restoration of degraded communal grazing lands through the establishment of pasture enclosures. A field experiment was conducted in northwestern Kenya to measure the emission of CO2, CH4 and N2O from soil under two pasture restoration systems; grazing dominated enclosure (GDE) and contractual grazing enclosure (CGE), and in the adjacent open grazing rangeland (OGR) as control. Herbaceous vegetation cover, biomass production, and surface (0–10 cm) soil organic carbon (SOC) were also assessed to determine their relationship with the GHG flux rate. Vegetation cover was higher enclosure systems and ranged from 20.7% in OGR to 40.2% in GDE while aboveground biomass increased from 72.0 kg DM ha−1 in OGR to 483.1 and 560.4 kg DM ha−1 in CGE and GDE respectively. The SOC concentration in GDE and CGE increased by an average of 27% relative to OGR and ranged between 4.4 g kg−1 and 6.6 g kg−1. The mean emission rates across the grazing systems were 18.6 μg N m−2 h−1, 50.1 μg C m−2 h−1 and 199.7 mg C m−2 h−1 for N2O, CH4, and CO2, respectively. Soil CO2 emission was considerably higher in GDE and CGE systems than in OGR (P < 0.001). However, non-significantly higher CH4 and N2O emissions were observed in GDE and CGE compared to OGR (P = 0.33 and 0.53 for CH4 and N2O, respectively). Soil moisture exhibited a significant positive relationship with CO2, CH4, and N2O, implying that it is the key factor influencing the flux rate of GHGs in the area. The results demonstrated that the establishment of enclosures in tropical rangelands is a valuable intervention for improving pasture production and restoration of surface soil properties. However, a long-term study is required to evaluate the patterns in annual CO2, N2O, CH4 fluxes from soils and determine the ecosystem carbon balance across the pastoral landscape.

中文翻译：

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牧场围栏增加了肯尼亚塞米里德牧场的土壤二氧化碳通量。

牧场围栏在恢复退化的土壤和植被方面起着重要作用，并且还可能影响土壤中主要温室气体（GHG）的排放。然而，在东非和肯尼亚没有研究通过建立牧场围栏恢复退化的公共牧场后直接测量温室气体的通量。在肯尼亚西北部进行了一次野外试验，以测量在两种牧场恢复系统下土壤中CO2，CH4和N2O的排放。放牧占主导的围栏（GDE）和合同放牧围栏（CGE），并在相邻的开放放牧牧场（OGR）中作为对照。还评估了草木植被覆盖度，生物量生产和地表（0-10厘米）土壤有机碳（SOC），以确定它们与温室气体通量率的关系。植被是较高的围护系统，从OGR的20.7％到GDE的40.2％，而地上生物量从OGR的72.0 kg DM ha-1分别增加到CGE和GDE的483.1和560.4 kg DM ha-1。相对于OGR，GDE和CGE中的SOC浓度平均增加了27％，介于4.4 g kg-1和6.6 g kg-1之间。N2O，CH4和CO2的放牧系统平均排放速率分别为18.6μgN m-2 h-1、50.1μgC m-2 h-1和199.7 mg C m-2 h-1。GDE和CGE系统的土壤CO2排放量显着高于OGR（P <0.001）。然而，与OGR相比，GDE和CGE中观察到的CH4和N2O排放量显着增加（CH4和N2O的P分别为0.33和0.53）。土壤水分与CO2，CH4和N2O呈显着正相关，暗示这是影响该地区温室气体通量率的关键因素。结果表明，在热带牧场建立围栏是提高牧草产量和恢复表层土壤特性的有价值的干预措施。但是，需要进行长期研究以评估土壤每年的CO2，N2O，CH4通量的分布方式，并确定整个牧区景观中的生态系统碳平衡。