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Publikasjoner

NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.

2026

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ABSTRACT This study evaluated the SWAT+ model in a Norwegian catchment with mixed forest-agriculture land use, tile drainage, and multiple lakes, and examined the added value of incorporating soft data as process-based constraints during calibration. The primary aim was to test whether such constraints improve hydrological consistency in addition to statistical fit. A stepwise methodology was applied, including parameter initialization, model verification, water balance soft calibration, and constraint-based hard calibration. We showed how each stage incrementally improved model performance. Three hydrological constraints were defined to represent water balance components (runoff coefficient), streamflow signatures (baseflow index), and expert knowledge of catchment behavior (tile flow ratio). Constraint-based calibration achieved slightly lower efficiency scores (NSE = 0.61, KGE = 0.72) than unconstrained calibration (NSE = 0.65, KGE = 0.77), reflecting the trade-off between optimizing performance metrics and ensuring realistic hydrological processes. The baseflow index was the most influential constraint, eliminating about 77% of non-behavioral simulations when assessed individually. The results also highlight the importance of lake initialization and the need for multiple performance metrics when tuning lake release parameters. Overall, integrating process-based knowledge strengthened internal consistency and increased confidence that SWAT+ performs well for the right reasons.

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ABSTRACT Increasing drought frequency and intensity affect biophysical functions of natural ecosystems. In tropical semi‐arid savannas, while immediate drought effects are well‐studied, the drought legacy effects on vegetation composition and associated ecosystem functions remain unclear. We used data of vegetation composition, net ecosystem CO 2 exchange, surface albedo and evapotranspiration (ET) in 2017–2022 from a savanna ecosystem, Southwest China, to investigate the legacy effect of an extreme drought event that occurred in 2019. Vegetation declined continuously for 3 post‐drought years. While tree numbers declined by 12%, shrub numbers dropped by 50% compared with pre‐drought levels, shifting vegetation dominance toward trees. This structural change caused sustained reductions in albedo and ET, which remained below pre‐drought levels, despite gross primary production recovering in the years immediately post‐drought. Vegetation shifts disproportionately impact ecosystem functions, with energy and water fluxes exhibiting greater vulnerability and potentially enhancing regional warming as droughts increase in Asian savannas.

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Sewage sludge-derived biochar, a carbon-rich material produced by the pyrolysis of sewage sludge, has emerged as a promising amendment for enhancing the fertility and biological quality of nutrient-poor sandy soils in tropical regions. We investigated the effects of sewage sludge (SS) and its biochar (SSB) on microbial indicators, nutrient dynamics, and sugarcane biomass growth in sandy soil over 120 days. Treatments included individual applications of SS (40 Mg ha−1) and SSB (20 Mg ha−1), their combinations at 75:25, 50:50, and 25:75 SS:SSB ratios, a mineral fertilizer, and an unfertilized control. Microbial biomass carbon (Cmic), basal C-CO2 flux, metabolic (qCO2) and microbial (qMic) quotients were monitored, along with ammonium and nitrate levels, available phosphorus (P), and carbon stock. SS promoted a rapid rise in microbial activity and Cmic, whereas SSB sustained these effects over time, demonstrating complementary roles. The 75:25 combination exhibited the strongest synergistic response, enhancing microbial efficiency (higher qMic and lower qCO2), P availability, and carbon storage. Ammonium and nitrate peaked during early and mid-stages, respectively, with the highest values under SS. At the same time, P availability and soil carbon stocks were maximized under 75:25. Sugarcane biomass increased significantly in this treatment, despite foliar N and P concentrations remaining below sufficiency levels. These results highlight clear synergistic interactions between SS and SSB, emphasizing that the 75:25 combination offers a balanced strategy to improve nutrient cycling, microbial functionality, and carbon stabilization in tropical sandy soils.

Sammendrag

Cover crops enhance soil quality and organic matter stability, yet the mechanisms linking belowground inputs to persistent soil organic matter (SOM) remain unclear. This study examined the effects of diversified cover cropping in barley systems on root biomass, SOM fractions, soil structure, microbial activity, and yield in central Norway (63.9° N), three years post-implementation. Six treatments were tested: (1) Control (barley without NPK), (2) Biochar-Fertilizer (barley + NPK + 3 Mg ha⁻¹ biochar), (3) Monocrop (barley), (4) Ryegrass (barley + ryegrass), (5) Clover (barley + ryegrass + white/red clover), and (6) Chicory (barley + ryegrass + red clover + chicory + bird’s-foot trefoil). Ryegrass and Clover systems produced 28.65 g m-² more root biomass at 0–13 cm (p < 0.05) and, along with Monocrop, stored 2.2 Mg ha-¹ more mineral-associated organic matter (MAOM) carbon and 0.2 Mg ha-¹ more MAOM nitrogen at 0–20 cm than other treatments. The Chicory system improved soil structure and biology, with higher aggregate stability, lower bulk density, and greater microbial abundance. Barley yields remained consistent across treatments, suggesting that cover cropping and low biochar inputs do not reduce productivity. Strong correlations (p < 0.01) between root biomass and MAOM stocks highlight root development as a key driver of SOM stabilization via organo-mineral associations. These findings underscore the role of root-enhancing cover crops in promoting MAOM formation and long-term SOM persistence, offering valuable insights for sustainable soil management.