Patterns of vegetation expansion during dune stabilization at the decadal scale

Abstract

AbstractThere is a global stabilization of coastal dunes, during which, the trajectory of vegetation expansion was rarely studied and, thus, still remains unclear. In this study, patterns and driving factors of vegetation expansion during dune stabilization were examined in three coastal dunefields in Victoria, Australia. Results show that the trajectory of vegetation expansion is fundamentally determined by dunefield topography. At the dunefield scale, vegetation colonization can take place at different parts in dunefield, including (1) the landward margins, where the ecosystem is frequently dominated by woody species and the soil is more mature with higher nutrients and water content; (2) the interdune depressions, where is usually dominated by lower elevations and shelters; and (3) the seaward deflation basins and plains, where vegetation shows a more discontinuous and patchy distribution. At the individual dune scale, vegetation usually expands vertically from the dune toe towards the upper dune slope at both the lee side and stoss face of dunes/dune ridges. The deflation basins are more likely to be free of vegetation establishment. Pre‐existing vegetation also plays a critical role in dune re‐vegetation, and subsequent vegetation expansion takes place around the vegetation patches, more usually towards the downwind direction, probably because it can provide seeds for subsequent vegetation spread. Once established, it can also change the micro‐climates by providing shelter, increasing the surface roughness and changing the wind regimes. More importantly, existing vegetation can form a ‘fertility island’ with higher nutrients, organic matter and water‐holding capacity. Conceptual models depicting the trajectory of vegetation expansion were also generalized. This research provides an original perspective and innovative insight into the patterns and driving factors of vegetation expansion during dune stabilization, under the background of global coastal ‘greening’, which could be helpful to identify opportunities for management interventions.