Does wind affect the orientation of vegetation stripes? A copula-based mixture model for axial and circular data

TL;DR

This paper introduces a copula-based mixture model to analyze how wind influences the orientation of vegetation stripes, revealing that wind direction significantly shapes plant patterning through shelter effects.

Contribution

It presents a novel copula-based bivariate distribution for mixed axial and circular data, enabling the study of environmental variable dependence on complex manifolds.

Findings

Wind significantly influences vegetation stripe orientation

Vegetation patterns are shaped by wind shelter mechanisms

The model effectively captures dependence between wind and plant orientation

Abstract

Motivated by a case study of vegetation patterns, we introduce a mixture model with concomitant variables to examine the association between the orientation of vegetation stripes and wind direction. The proposal relies on a novel copula-based bivariate distribution for mixed axial and circular observations and provides a parsimonious and computationally tractable approach to examine the dependence of two environmental variables observed in a complex manifold. The findings suggest that dominant winds shape the orientation of vegetation stripes through a mechanism of neighbouring plants providing wind shelter to downwind individuals.