Long‐term impacts of post‐fire mulching on ground‐dwelling arthropod communities in a eucalypt plantation

Abstract

In the past decades, Portugal like several other Mediterranean countries has been affected by frequent wildfires. This has led to various field tests of post-fire soil conservation measures and, in particular, mulching with forest slash residues. While forest residue mulching was shown to be highly effective in reducing post-fire erosion, its side effects on soil fauna communities have not been studied and are also difficult to predict from the – scarce – literature on mulch effects in general. Therefore, this study compared the abundance, diversity and taxonomic and functional composition of the ground-dwelling arthropod communities of three mulched and, as control, three untreated erosion plots of roughly 100 m2 that had been installed in a eucalypt plantation almost immediately after a wildfire in 2010, some five years earlier. This was done using three pitfall traps per plot, placed at the lower, middle and upper part of the study slope. Roughly five years after mulching, its impacts on the ground-dwelling arthropod were rather limited, especially compared to its effect on overall soil erosion rates. One of the few exceptions was the abundance of the Hymenoptera – one of the most frequently occurring orders – which was significantly lower in the mulched than control plots. This and other near significant mulching impacts found in this study plainly justify a follow-up study on shortterm effects.