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Data from: The impact of biodegradable microplastics on soil priming effects in poplar shelterbelts across an afforestation gradient
Summary
"Biodegradable" plastics, often used in farming, are marketed as an eco-friendly alternative to regular plastic, but this study found that as they break down in tree-planted soils, they can actually cause soil to release more stored carbon into the air—especially in forests planted 10-15 years ago. This matters because these soils are meant to act as carbon storage that helps fight climate change, and losing that stored carbon could undercut the environmental benefits these tree plantings were designed to provide.
The widespread agricultural use of biodegradable plastics may cause the persistence of biodegradable microplastics (BMPs) in afforested soils, which could compromise the soil organic carbon (SOC) sequestration in shelterbelts through priming effects. However, the influence of BMPs on SOC priming effects across different afforestation gradients remains unclear. Polyhydroxyalkanoates (PHA) and polylactic acid (PLA), two typical BMPs, were investigated for their influence on the priming effect in soils collected from abandoned farmland and poplar shelterbelts aged 5, 10, 15, and 20 years (5‑, 10‑, 15‑, and 20‑year stands). The difference in isotopic values (δ13C) between BMPs and SOC (> 10‰) was employed to differentiate the sources of CO2 emissions. Our results showed that PHA and PLA induced positive priming effects across the afforestation gradient through modifying soil physicochemical and aggregate properties, as well as reshaping bacterial community composition via these changes. The priming effects of PHA and PLA ranged from 83.00% to 295.41% and from 9.79% to 80.91%, respectively. Both effects initially increased and then decreased along the afforestation gradient, a trend that may be partly explained by the contrasting patterns of SOC content and the C/N ratio. This short‑term experiment demonstrated that BMPs induced stronger positive priming in 5‑, 10‑, and 15‑year stands than in abandoned farmland, peaking at 10‑ and 15‑year stands. Therefore, to minimize BMP‑induced SOC loss in afforested soils, we recommend: (1) assess BMP contamination pre‑afforestation, prioritizing low‑risk sites and applying remediation where needed; (2) enhance post-afforestation monitoring of BMP contamination, particularly in 10‑ and 15‑year stands.