Nutrient limitations regulate soil greenhouse gas fluxes from tropical forests: evidence from an ecosystem-scale nutrient manipulation experiment in Uganda

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dc.contributor.authorTamale, Joseph
dc.contributor.authorHüppi, Roman
dc.contributor.authorGriepentrog, Marco
dc.contributor.authorTuryagyenda, Laban Frank
dc.contributor.authorDoetterl, Sebastian
dc.contributor.authorStraaten, Oliver van
dc.date.accessioned2023-05-05T15:58:14Z
dc.date.available2023-05-05T15:58:14Z
dc.date.issued2021
dc.description.abstractSoil macronutrient availability is one of the abiotic controls that alters the exchange of greenhouse gases (GHGs) between the soil and the atmosphere in tropical forests. However, evidence on the macronutrient regulation of soil GHG fluxes from central African tropical forests is still lacking, limiting our understanding of how these biomes could respond to potential future increases in nitrogen (N) and phosphorus (P) deposition. The aim of this study was to disentangle the regulation effect of soil nutrients on soil GHG fluxes from a Ugandan tropical forest reserve in the context of increasing N and P deposition. Therefore, a large-scale nutrient manipulation experiment (NME), based on 40 m×40 m plots with different nutrient addition treatments (N, P, N + P, and control), was established in the Budongo Central Forest Reserve. Soil carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes were measured monthly, using permanently installed static chambers, for 14 months. Total soil CO2 fluxes were partitioned into autotrophic and heterotrophic components through a root trenching treatment. In addition, soil temperature, soil water content, and nitrates were measured in parallel to GHG fluxes. N addition (N and N + P) resulted in significantly higher N2O fluxes in the transitory phase (0–28 d after fertilization; p<0.01) because N fertilization likely increased soil N beyond the microbial immobilization and plant nutritional demands, leaving the excess to be nitrified or denitrified. Prolonged N fertilization, however, did not elicit a significant response in background (measured more than 28 d after fertilization) N2O fluxes. P fertilization marginally and significantly increased transitory (p=0.05) and background (p=0.01) CH4 consumption, probably because it enhanced methanotrophic activity. The addition of N and P (N + P) resulted in larger CO2 fluxes in the transitory phase (p=0.01), suggesting a possible co-limitation of both N and P on soil respiration. Heterotrophic (microbial) CO2 effluxes were significantly higher than the autotrophic (root) CO2 effluxes (p<0.01) across all treatment plots, with microbes contributing about two-thirds of the total soil CO2 effluxes. However, neither heterotrophic nor autotrophic respiration significantly differed between treatments. The results from this study suggest that the feedback of tropical forests to the global soil GHG budget could be disproportionately altered by increases in N and P availability over these biomes.en_US
dc.identifier.citationTamale, J., Hüppi, R., Griepentrog, M., Turyagyenda, L. F., Barthel, M., Doetterl, S., ... & Van Straaten, O. (2021). Nutrient limitations regulate soil greenhouse gas fluxes from tropical forests: evidence from an ecosystem-scale nutrient manipulation experiment in Uganda. Soil, 7(2), 433-451.https://doi.org/10.5194/soil-7-433-2021en_US
dc.identifier.urihttps://nru.uncst.go.ug/handle/123456789/8633
dc.language.isoenen_US
dc.publisherSoilen_US
dc.subjectEcosystem-scale nutrient manipulation experimenten_US
dc.subjectTropical forestsen_US
dc.subjectSoil greenhouse gas fluxesen_US
dc.subjectNutrient limitationsen_US
dc.titleNutrient limitations regulate soil greenhouse gas fluxes from tropical forests: evidence from an ecosystem-scale nutrient manipulation experiment in Ugandaen_US
dc.typeArticleen_US
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