Short-term arthropod recovery in Eucalyptus plantations after harvesting is not affected by different residue management practices

Abstract

To sustainably manage soils, we need to understand the impact of management practices on soil biota. A major disturbance in commercial tree plantations is the management of the woody residue that remains in situ after harvesting. We examine the impact of different harvest residue management practices on soil biota in a forestry landscape in KwaZulu-Natal, South Africa on nutrient-rich clay soils. We assess four different management practices and unmanaged grassland at three time periods: prior to implementation of residue management, directly after implementation, and six months after implementation. Management practices are 1) on-site retention of unburned harvest residue, 2) residue removal off site, 3) high-intensity burning and 4) low-intensity burning of residue. We examine the response of ant and springtail taxonomic and functional diversity, assemblage composition, and soil biological activity. We also assess whether soil biological activity at different soil depths differs among treatments. Across all sites, all biotic responses declined in the post-treatment, but recovery of the focal arthropods after six months was low regardless of the type of residue management practice. At each time period, ant and springtail taxonomic and functional diversity showed no difference among management practices. Soil biological activity showed minor differences between practices after implementation overall, and at different soil depths, and recovery was similar between residue management practices after six months. After six months, soil biological activity recovered to ∼ 50 % in all sites. Thus, in the short term, soil biota in this region are not differentially impacted by different residue management practices, despite major variations in conditions. We recommend further assessments in different soil types and over a longer period to assess the full impact of slash management on these functionally important soil arthropods.