Desert and semi-desert plants are often associated with a distinct soil biota under the plants and close to the root system. We aimed to understand if similar effects could be found in the taxonomically isolated desert gymnosperm Welwitschia mirabilis in the Namib Desert, and whether this island effect varied with climate and with gender of plants. We took soil cores adjacent to the plants in environments ranging from extreme desert to arid shrubland, and in nearby control sites between the plants. Soil chemistry was analysed, and DNA was extracted and sequenced for the bacterial 16s region. Soil under the plants was richer in organic C, N, and moisture. Despite the range of climates, the soil around Welwitschia plants was consistently associated with a particular bacterial community composition that was distinct from samples further away. Compared to unvegetated control patches, bacterial diversity close to the plants was reduced. In the plant-associated soil community, there was a clear gender effect across all sites with a distinct community composition and greater diversity under male plants. It is unclear what differences in the soil environment might be producing these gender-associated differences, which provide an additional dimension to the fertile island effect.

中文翻译：

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千岁兰植物对土壤微生物的“肥力岛效应”受植物性别的影响。

荒漠和半荒漠植物通常与植物下方且靠近根系的独特土壤生物区系相关。我们的目的是了解是否可以在纳米布沙漠的分类学上孤立的沙漠裸子植物Wilwitschia mirabilis中找到类似的效果，以及这种岛屿效应是否随气候和植物性别而变化。我们在从极端沙漠到干旱灌木丛的环境中以及植物之间附近的控制点中的植物附近取了土壤核心。分析土壤化学，提取DNA并进行细菌16s区域测序。植物下的土壤富含有机碳，氮和水分。尽管气候变化，千岁兰周围的土壤植物始终与特定的细菌群落组成相关，而该细菌群落组成与远处的样品不同。与无植被的对照斑块相比，靠近植物的细菌多样性降低了。在与植物相关的土壤群落中，所有地点均存在明显的性别效应，其中雄性植物具有明显的群落组成和更大的多样性。目前尚不清楚土壤环境中的哪些差异可能会导致这些性别相关的差异，这为肥沃的岛屿效应提供了新的维度。