Data from: Contrasting global patterns of spatially periodic fairy circles and regular insect nests in drylands

Numerical analysis of spatial pattern is widely used in ecology to
describe the characteristics of floral and faunal distributions. These
methods allow attribution of pattern to causal mechanisms by uncovering
the specific signatures of patterns and causal agents. For example,
grassland‐gap patterns called fairy circles (FCs) in Namibia and Australia
are characterized by highly regular and homogenous distributions across
landscapes that show spatially periodic ordering. These FCs have been
suggested to be caused by both social insects and competitive plant
interactions. We compared eight Namibian and Australian FC patterns and
also modeled FCs to 16 patterns of social insect nests in Africa,
Australia, and America that include the most regular termite mound
patterns known. For pattern‐process inference, we used spatial statistics
based on both nearest‐neighbor analysis and neighborhood‐density
functions. None of the analyzed insect‐nest distributions attain the
spatially periodic ordering that is typical of FCs. The inherently more
variable patterns of termite and ant nests are commonly attributable to
well documented aspects of the faunal life‐history. Our quantitative
evidence from drylands shows that the more variable insect‐nest
distributions in water‐limited environments cannot explain the
characteristic spatial signature of FCs. The analysis demonstrates the
interpretation of scale‐dependent neighborhood‐density functions and that
it is the identification of unique spatial signatures in regular patterns
that need to be linked to process. While our results cannot verify a
specific hypothesis, they support the hypothesis that FCs in these
drylands are more likely an emergent vegetation pattern caused by strong
plant competition for water.