Namibian fairy circles: Hostile territory for soil nematodes

Fairy circles are rings of grass (2-12 m diameter) with centers of bare soil that are found in some arid grasslands. Above- and belowground chemical and biological processes have been explored in an ongoing debate about the ultimate causes of this pattern. Belowground biota, including beneficial and pathogenic nematodes in the soil food web, may both influence and respond to the formation of fairy circles. For example, root-feeding nematodes have the potential to enhance plant water stress, promoting the spatial organization into rings to minimize competition. 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 beneath the vegetation rings that define fairy circles and in soils in the vegetated matrix surrounding the rings, demonstrating the positive impact of plant-derived resources (i.e., roots and organic matter) on nematode co..., Nine fairy circle sites in Namibia were sampled, spanning a 900-km north-south range that encompasses most of the distribution of fairy circles in Namibia. Soils were collected between 24 March – 31 October 2020.  Six representative circles were selected at each site within an approximately 1-ha area. At each circle, four subsamples were collected and combined from the center of the circle (“center”) to a depth of 0-10 cm using a plastic scoop. Similarly, four subsamples were collected and combined from the soil beneath the grass composing the ring of vegetation defining the margin of the fairy circle (“ring”), and four subsamples were collected and combined from the inter-circle matrix (“matrix”), at least 1 m from the ring.  A total of 162 samples were collected (nine sites x six rings x three positions). Soils were sieved (2-mm mesh) to remove rocks and transferred to plastic bags.
Soil moisture was determined gravimetrically (24 h at 105°C). Soil organic matter was measu..., , # Namibian fairy circles: Hostile territory for soil nematodes

[https://doi.org/10.5061/dryad.6djh9w1c2](https://doi.org/10.5061/dryad.6djh9w1c2)

## Description of the data and file structure

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. The objective of this study was to investigate the relationship between the fairy circle vegetation pattern and soil nematode diversity and abundance. Soils were collected between 24 March – 31 October 2020. 

### Files and variables

#### File: TreonisFairyCircleNematodes.csv

**Description:** Soil nematode communities associated with *Stipagrostis* fairy circles in the Namib Desert of Namibia in southern Africa. 

##### Variables

* GPS:  Coordinates for site
* site: Name of field site
* position: location of sample within fairy circle vegetation pattern (center = un-vegetated center, ring = grass surrounding center, matrix = vegetation ...,