Despite its importance for carbon stocks accounting, belowground biomass (BGB) has seldom been measured due to the methodological complexity involved. In this study, we assess woody BGB and related carbon stocks, soil properties and human impact on two common suffrutex grasslands (Brachystegia- and Parinari grasslands) on the Angolan Central Plateau. Data on BGB was measured by direct destructive sampling. Soil samples were analysed for select key parameters. To investigate vegetation dynamics and human impact, we used Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) and fire data retrieved via Google Earth Engine. Mean belowground woody biomass of sandy Parinari grasslands was 17 t/ha and 44 t/ha in ferralitic Brachystegia grasslands of which 50% correspond to carbon stocks. As such, the BGB of Brachystegia grasslands almost equals the amount of aboveground biomass (AGB) of neighbouring miombo woodlands. Almost the entire woody BGB is located in the top 30 cm of the soil. Soils were extremely acid, showing a low nutrient availability. Both grassland types differed strongly in EVI and fire seasonality. The Parinari grasslands burnt almost twice as frequent as Brachystegia grasslands in a 10-year period. Our study emphasizes the high relevance of BGB in suffrutex grasslands for carbon stock accounting.

中文翻译：

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安哥拉中南部 Suffrutex 草原：“非洲地下森林”的地下生物量、根系结构、土壤特征和植被动态

尽管地下生物量 (BGB) 对碳储量核算很重要，但由于所涉及的方法复杂性，它很少被测量。在这项研究中，我们评估了木质 BGB 和相关的碳储量、土壤特性和人类对两种常见的 suffrutex 草原的影响（短痛- 和帕里纳里草原）在安哥拉中央高原。BGB 上的数据是通过直接破坏性采样测量的。分析土壤样品的选定关键参数。为了研究植被动态和人类影响，我们使用了中分辨率成像光谱仪 (MODIS) 增强植被指数 (EVI) 和通过 Google 地球引擎检索的火灾数据。沙地平均地下木质生物量帕里纳里草原为 17 吨/公顷和 44 吨/公顷的铁质短痛其中 50% 对应于碳储量的草地。因此，BGB 的短痛草原几乎等于邻近 miombo 林地的地上生物量 (AGB)。几乎整个木质 BGB 都位于土壤的顶部 30 厘米。土壤酸性极强，养分利用率低。两种草原类型在 EVI 和火灾季节性方面差异很大。这帕里纳里草原被烧毁的频率几乎是短痛10年的草原。我们的研究强调了 BGB 在 suffrutex 草原中与碳储量核算的高度相关性。