Short-term impacts of soil enzyme activity in rhizosphere and bulk soils by forest gap size of a Platycladus orientalis plantation

Aim of study: We investigated how changes in forest gap size influence soil enzyme activities in both the rhizosphere and bulk soils, mediated by rhizosphere effects (RE). Area of study: Xuzhou, Jiangsu Province, China. Material and methods: The study was conducted in a 46-year-old Platycladus orientalis (L.) Franco, 1950 plantation in Xuzhou and its aim was accomplished by sampling soils, one year after forest gaps establishment, from three levels of forest gap sizes: small (S, with a radius of 4 m), medium (M, with a radius of 8 m), and large (L, with a radius of 12 m), as well as control plots (CK, without any gaps). Soil enzyme activities, including peroxidase (PER), dehydrogenase (DEH), urease (URE), and invertase (INV), were quantified. Main results: Gap size and season strongly affected the RE on DEH and URE. The interaction of gap size, location and season significantly affected the RE on DEH, URE, and INV. Enzyme activities in bulk soils were more sensitive to changes in nutrient availability than in rhizosphere soils, and microbial biomass played a crucial role in modulating enzyme activity. Furthermore, both L and S forest gaps exerted an influence on the RE of enzyme activity, with L gaps exhibiting the most extensive impact. Research highlights: This study observed that the RE of soil enzyme activity did not increase with the enlargement of forest gap size. However, in L forest gaps, its impact range was more extensive.