The University of Western Australia, School of Plant Biology, Crawley 6009, WA, Australia; Kings Park and Botanic Garden, Kings Park, Perth 6005, WA, Australia; Curtin University, Department of Environment and Agriculture, Perth 6845, WA, Australia.
The University of Western Australia, School of Plant Biology, Crawley 6009, WA, Australia; Kings Park and Botanic Garden, Kings Park, Perth 6005, WA, Australia.
Sci Total Environ. 2016 Dec 1;572:1385-1394. doi: 10.1016/j.scitotenv.2016.02.086. Epub 2016 Feb 28.
Soil respiration (Rs) is the second largest carbon flux in terrestrial ecosystems and therefore plays a crucial role in global carbon (C) cycling. This biogeochemical process is closely related to ecosystem productivity and soil fertility and is considered as a key indicator of soil health and quality reflecting the level of microbial activity. Wildfires can have a significant effect on Rs rates and the magnitude of the impacts will depend on environmental factors such as climate and vegetation, fire severity and meteorological conditions post-fire. In this research, we aimed to assess the impacts of a wildfire on the soil CO fluxes and soil respiration in a semi-arid ecosystem of Western Australia, and to understand the main edaphic and environmental drivers controlling these fluxes for different vegetation types. Our results demonstrated increased rates of Rs in the burnt areas compared to the unburnt control sites, although these differences were highly dependent on the type of vegetation cover and time since fire. The sensitivity of Rs to temperature (Q10) was also larger in the burnt site compared to the control. Both Rs and soil organic C were consistently higher under Eucalyptus trees, followed by Acacia shrubs. Triodia grasses had the lowest Rs rates and C contents, which were similar to those found under bare soil patches. Regardless of the site condition (unburnt or burnt), Rs was triggered during periods of higher temperatures and water availability and environmental factors (temperature and moisture) could explain a large fraction of Rs variability, improving the relationship of moisture or temperature as single factors with Rs. This study demonstrates the importance of assessing CO fluxes considering both abiotic factors and vegetation types after disturbances such as fire which is particularly important in heterogeneous semi-arid areas with patchy vegetation distribution where CO fluxes can be largely underestimated.
土壤呼吸（Rs）是陆地生态系统中第二大碳通量，因此在全球碳（C）循环中起着至关重要的作用。这一生物地球化学过程与生态系统生产力和土壤肥力密切相关，被认为是反映土壤微生物活性水平的土壤健康和质量的关键指标。野火会对 Rs 速率产生重大影响，其影响的大小将取决于环境因素，如气候和植被、火灾严重程度以及火灾后的气象条件。在这项研究中，我们旨在评估野火对西澳大利亚半干旱生态系统中土壤 CO 通量和土壤呼吸的影响，并了解控制不同植被类型这些通量的主要土壤和环境驱动因素。我们的研究结果表明，与未燃烧的对照点相比，燃烧区的 Rs 速率增加，尽管这些差异高度依赖于植被覆盖类型和火灾后的时间。与对照相比，燃烧区 Rs 对温度的敏感性（Q10）也更大。桉树和金合欢灌丛下的 Rs 和土壤有机碳始终较高，三齿稃草的 Rs 速率和 C 含量最低，与裸露土壤斑块下的含量相似。无论地点条件（未燃烧或燃烧）如何，Rs 都是在温度和水分可用性较高的时期触发的，环境因素（温度和水分）可以解释 Rs 变异性的很大一部分，改善了水分或温度作为单一因素与 Rs 的关系。这项研究表明，在像火灾这样的干扰后，评估 CO 通量时考虑非生物因素和植被类型非常重要，特别是在具有斑块状植被分布的异质半干旱地区，这些地区的 CO 通量可能会被大大低估。
