Soil nematode communities vary among populations of the iconic desert plant, Welwitschia mirabilis

Treonis, Amy M.; Marais, Eugene; Maggs-Kölling, Gillian

doi:10.1016/j.pedobi.2024.150943

Cited by 4 publications

(1 citation statement)

References 35 publications

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“…Few studies have investigated soil nematodes in the Namib Desert, focusing on their geographical density, functional structure, and diversity 74 – 76 . Like the scope of our study, these prior studies were interested in the effects of perennial plants as resource islands on the density of soil nematodes, in contrast to the open desert lacking any vegetation cover.…”

Section: Discussionmentioning

confidence: 99%

The hidden oases: unveiling trophic dynamics in Namib's fog plant ecosystem

Gan,

Hohberg,

Schneider

et al. 2024

Sci Rep

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The Namib Desert is a hyperarid coastal desert where fog is a major moisture source. We hypothesized that the fog-harvesting grass Stipagrostis sabulicola establishes an important ecological niche, termed the "Fog-Plant-Oases" (FPOs), and serves as the primary carbon source for the invertebrate community. To determine this, we measured the natural variations of the stable carbon and nitrogen isotopes (δ13C and δ15N) of invertebrates as well as that of plant biomass and belowground detritus and estimated the contributions of the fog plants in their diets. Our findings revealed a complex trophic structure and demonstrated that S. sabulicola fuels carbon flow from lower to higher trophic levels in the aboveground food web. The distinct δ13C values of bacterial- and fungal-feeding nematodes indicated however the separation of the aboveground niche, which is primarily sustained by S. sabulicola, from the belowground niche, where wind-blown sediments may serve as the main energy source for the soil biota. Our findings further accentuate the critical role of S. sabulicola FPOs in establishing complex trophic dynamics and a distinctive food web within the hyperarid Namib dunes.

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Section: Discussionmentioning

confidence: 99%

The hidden oases: unveiling trophic dynamics in Namib's fog plant ecosystem

Gan,

Hohberg,

Schneider

et al. 2024

Sci Rep

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Hierarchical Patterns of Soil Biodiversity in the Atacama Desert: Insights Across Biological Scales

Villegas,

Pettrich,

Acevedo-Trejos

et al. 2024

Preprint

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Species diversity and distribution, in relation to how they interact with their environment has for long been a major focus of ecological research. Particularly for soil ecosystems, information about geographical patterns of biota is scarce despite the primordial role of soils as ecosystem service providers. The Atacama Desert, the driest non-polar desert on earth, where water is scarce, high salinity patches are frequent and high concentrations of metals are present in water bodies, only specialised taxa can survive. This desert supports some microbial life-forms, plant, vertebrates. Above ground invertebrates have also been reported to occur throughout its extension, but its soils have not been comprehensively analysed. By studying the Atacama as a system with different extreme habitats we aim to better understand and predict resilience of soil organisms in times of global aridification. Nematodes are one of the most important groups of soil organisms in terms of numbers and biodiversity. Here, we investigated diversity of soil nematodes at the genetic, taxonomic, community and life-cycle levels in the Atacama. We find distinct patterns in their assemblages along the different habitats in the desert: dune systems, high altitude mountains, saline lakes, river valleys and fog oases, characterizing some desert soil habitats as stable systems and others as disturbed. We also find that distribution of asexual taxa appears to be in the marginal ranges of high altitudes, and that the distribution of genera richness in the Atacama increases towards the south following a latitudinal diversity gradient, as well as with increasing precipitation. Our work shows that even under extreme environmental conditions healthy soil communities can persist, but we see indicatives of local degradation due to aridification during global change.

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Namibian fairy circles: Hostile territory for soil nematodes

Treonis,

Bell,

Marais

et al. 2024

Preprint

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Fairy circles are rings of grass with centers of bare soil that are found in some arid grasslands. Above- and belowground chemical and biological attributes of fairy circles have been explored in an ongoing debate about the ultimate causes of this pattern. We studied the soil nematode communities associated with Stipagrostis fairy circles along a 900-km range in the Namib Desert of Namibia in southern Africa. Nematode abundance and diversity were highest in soils along the vegetation rings that define fairy circles and in soils in the vegetated matrix surrounding the bare circles, demonstrating the positive impact of plant-derived resources on nematode communities. In contrast, soils from the bare centers of fairy circles had lower organic matter content and were nearly defaunated, averaging only 9.9 ± 1.7 nematodes 100 g-1 soil. Bacterial-feeding Acrobeloides nematodes were the only taxa over-represented in center soils in comparison to ring soils. Our results indicate that nematode communities are influenced by the unique soil environments that the fairy circle vegetation pattern generates and suggest that the soils at the centers of fairy circles are uniquely hostile habitat for soil organisms as well as plants. Co-occurrence network analysis of nematode communities elucidated relationships among the taxa. For example, the abundances of dorylaims and Nothacrobeles were positively correlated across all soil positions, suggesting they have overlapping ecological niches. In ring soils, the abundances of fungal-feeding Aphelenchoides, Ditylenchus, and Hexatylus were positively correlated, likely due to enhanced fungal communities in these plant-influenced soils. Panagrobelus demonstrated niche specialization by being negatively correlated to two other bacterial-feeding taxa (Elaphonema in matrix soils and Acrobeloides in ring soils). The co-occurrence patterns revealed by these relatively low diversity communities provide insights into the potential roles of nematode interactions as well as environmental factors in community assembly.

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Soil nematode communities vary among populations of the iconic desert plant, Welwitschia mirabilis

Cited by 4 publications

References 35 publications

The hidden oases: unveiling trophic dynamics in Namib's fog plant ecosystem

The hidden oases: unveiling trophic dynamics in Namib's fog plant ecosystem

Hierarchical Patterns of Soil Biodiversity in the Atacama Desert: Insights Across Biological Scales

Namibian fairy circles: Hostile territory for soil nematodes

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