Soil greenhouse gas fluxes following conventional selective and reduced-impact logging in a Congo Basin rainforest
Rodine Tchiofo Lontsi, Marife D. Corre, Najeeb Al-Amin Iddris, Edzo Veldkamp
Abstract
Abstract Selective logging is among the main causes of tropical forest degradation, but little is known about its effects on greenhouse gas (GHG) fluxes from highly weathered Ferralsol soils in Africa. We measured soil CO 2 , N 2 O, and CH 4 fluxes, and their soil controlling factors at two forests that had undergone conventional selective logging and reduced-impact logging in Cameroon. Each logging system had four replicate plots, each included the disturbed strata (road, logging deck, skidding trail, and felling gap) and an undisturbed reference area. Measurements were conducted monthly from September 2016 to October 2017. Annual GHG fluxes ranged from 4.9 to 18.6 Mg CO 2 –C, from 1.5 to 79 kg N 2 O–N, and from − 4.3 to 71.1 kg CH 4 –C ha −1 year −1 . Compared to undisturbed areas, soil CO 2 emissions were reduced and soil CH 4 emissions increased in skidding trails, logging decks and roads ( P < 0.01) whereas soil N 2 O emissions increased in skidding trails ( P = 0.03–0.05). The combined disturbed strata had 28% decrease in soil CO 2 emissions, 83% increase in soil N 2 O emissions, and seven times higher soil CH 4 emissions compared to undisturbed area ( P ≤ 0.01). However, the disturbed strata represented only 4–5% of the area impacted in both logging systems, which reduced considerably the changes in soil GHG fluxes at the landscape level. Across all strata, soil GHG fluxes were regulated by soil bulk density and water-filled pore space, indicating the influence of soil aeration and gas diffusion, and by soil organic carbon and nitrogen, suggesting the control of substrate availability on microbial processes of these GHG.