Within tropical forest ecosystems, wetlands such as swamp forests are an important interface between the terrestrial and aquatic landscape. Despite this assumed importance, there is a paucity of carbon flux data from wetlands in tropical Africa. Therefore, the magnitude and source of carbon dioxide (CO2) fluxes, carbon isotopic ratios, and environmental conditions were measured for 3 years between 2019 and 2022 in a seasonally flooded forest and a perennially flooded forest in the Cuvette Centrale of the Congo Basin. The mean surface fluxes for the seasonally flooded site and the perennially flooded site were 2.36 +/- 0.51 and 4.38 +/- 0.64 mu molm-2s-1, respectively. The time series data revealed no marked seasonal pattern in CO2 fluxes. As for the environmental drivers, the fluxes at the seasonally flooded site exhibited a positive correlation with soil temperature and soil moisture. Additionally, the water level appeared to be a significant factor, demonstrating a quadratic relationship with the soil fluxes at the seasonally flooded site. delta 13C values showed a progressive increase across the carbon pools, from aboveground biomass to leaf litter and then to soil organic carbon (SOC). However, there was no significant difference in delta 13C enrichment between SOC and soil-respired CO2. This lack of enrichment can be attributed to either a significant contribution from the autotrophic component of soil respiration or closed system dynamics.An in-situ-derived gas transfer velocity (k600=2.95 cm h-1) was used to calculate the aquatic CO2 fluxes at the perennially flooded site. Despite the low k600, relatively high CO2 surface fluxes were found due to very high partial pressure of CO2 (pCO2) values measured in the flooding waters. Overall, these results offer a quantification of the CO2 fluxes from forested wetlands and provide insights into the temporal variability of these fluxes and their sensitivity to environmental drivers.

The "Tool for Agroecology Performance Evaluation" (TAPE) was developed under the coordination of the Food and Agriculture Organisation of the United Nations (FAO) to assess the sustainability performance of agroecosystems. The assessment is mainly based on a 2-3-hour farm interview, in which a wide variety of data is collected. The environmental dimension has so far been represented in TAPE by two simple indices: A soil index, which is based on a visual analysis of the soil, and a biodiversity index, which is primarily based on the Gini-Simpson index of crops grown and animals kept. While the TAPE biodiversity index is crucial, it does not yet take into account so-called unplanned biodiversity, i.e. the impact of on-farm management practices on wild species. We have therefore expanded TAPE to include this aspect. Direct surveys of wildlife biodiversity in the field were not possible in TAPE, as this would have far exceeded the time required for data collection. Consequently, we based the newly developed biodiversity index on the indirect European BioBio method. The new index consists of ten indicators, which can take values between 0 and 100% and be aggregated to form the overall index. Examples of these indicators are field size, nitrogen application or stocking density. The new index was developed and tested on selected Swiss farms, where the comparison with a much more comprehensive and time-consuming method showed a positive correlation (r = 0.56, p-value = 0.009). The new index has so far been used in Switzerland (21 farms) and in Kenya (103 farms). In Switzerland, the field size and land use change indicators performed best (values > 75%), while the indicators tree habitat, nitrogen application, field operations and grazing intensity performed poorly (values > 50%). In Kenya, the field size, land use change, pesticide and field operations indicators reached values above 75%, while the tree habitat, grazing intensity and semi-natural habitat indicators had values clearly below 50%.

Description of the subject. Located in the southern part of Lake Kivu, this study attempted to investigate the factors controlling spatial-temporal variations of sediment yields in two catchments with contrasting land use (pristine forest versus agriculture). Objectives. This study aimed to investigate the temporal dynamics of suspended sediment export and to quantify sediment load in catchments with contrasting land uses in the Lake Kivu region. Method. Daily water discharge into vegetation and rainfall erosivity were analyzed to evaluate their influence on discharge and sediment yield. Results. We found that a few large storm events contributed disproportionally highly to the export of sediments for the agricultural catchment where an area of approximately 100 ha covered with sediments was present. A linear regression model was able to successfully predict monthly sediment export using only rainfall erosivity, topography and vegetation cover (R2 = 0.87***). However, vegetation indices derived from remote sensing could only explain 20% of the observed variability in soil cover management. We obtained the annual sediment yield (SY) of 0.5 t.ha-1.yr-1 and 15.3 t.ha-1.yr-1 for the pristine forest and cultivated catchment, respectively. The SY values in the cultivated catchment are among the highest reported for the region and are attributed to the low vegetation cover and frequent storms, minimal application of soil conservation measures, and accelerated deforestation. Conclusion. Methods for reducing TSS export should therefore be initiated in the agricultural catchments to protect the soil on the slopes and prevent further soil degradation in this region.

Description of the subject. Located in the southern part of Lake Kivu, this study attempted to investigate the factors controlling spatial-temporal variations of sediment yields in two catchments with contrasting land use (pristine forest versus agriculture). Objectives. This study aimed to investigate the temporal dynamics of suspended sediment export and to quantify sediment load in catchments with contrasting land uses in the Lake Kivu region. Method. Daily water discharge into vegetation and rainfall erosivity were analyzed to evaluate their influence on discharge and sediment yield. Results. We found that a few large storm events contributed disproportionally highly to the export of sediments for the agricultural catchment where an area of approximately 100 ha covered with sediments was present. A linear regression model was able to successfully predict monthly sediment export using only rainfall erosivity, topography and vegetation cover (R2 = 0.87***). However, vegetation indices derived from remote sensing could only explain 20% of the observed variability in soil cover management. We obtained the annual sediment yield (SY) of 0.5 t·ha-1·yr-1 and 15.3 t·ha-1·yr-1 for the pristine forest and cultivated catchment, respectively. The SY values in the cultivated catchment are among the highest reported for the region and are attributed to the low vegetation cover and frequent storms, minimal application of soil conservation measures, and accelerated deforestation. Conclusion. Methods for reducing TSS export should therefore be initiated in the agricultural catchments to protect the soil on the slopes and prevent further soil degradation in this region.

In order to fulfil the requirements of the Agriculture Act and the Ordinance on the Assessment of Sustainability, the Swiss Federal Research Centre Agroscope assesses the quantitative and qualitative impacts of agriculture on the environment using regional and farm-related eco-indicators. This is done by the monitoring of the Swiss agri-environmental system (MAUS). Thematically, these indicators cover a wide range of agroecological hotspots, such as humus, heavy metal and nutrient balances, use and risks of plant protection products, potential impact on biodiversity, greenhouse gas emissions and others. Agroscope bases the calculation of the indicators largely on existing data. To supplement and improve the quality of this data, MAUS is currently launching projects to acquire and integrate data from remote sensing, online surveys and farm management information systems (FMIS). Integrating FMIS data essentially means requesting data that is already collected by farmers for their farm management and in order to receive direct payments. A large part of this is field calendar data, which describes what happened in a field after the previous crop was harvested: e.g., how was the seedbed prepared, what fertilisation and plant protection measures were carried out before the crop was harvested, etc. There are various large gaps in the level of detail and scope of the FMIS available on the market compared to what is needed to calculate the indicators. Therefore, solutions are needed that allow the farms providing data to supplement missing information and, where necessary, to specify the entries for MAUS. As part of a pilot project, a technical solution was developed with one of the Swiss providers and is currently being implemented. This has shown that, in addition to a precise definition of requirements, constant and lively dialogue is important. A comprehensive data set that exemplifies how operating data must arrive at MAUS not only helps with final testing, but also with understanding the implementation. In the near future, other interested FMIS are to supplement their platforms so that data can be supplied to MAUS. In the collaboration between Agroscope and the interested providers, both parties will benefit from the preliminary work and the findings of the pilot project.

For the agri-environmental monitoring of Switzerland, nitrogen balances on farm level for all Swiss farms were calculated and aggregated in order to obtain regionalized nitrogen balances. This monitoring attempts to incorporate as much existing data as possible to minimize multiple data collections from farmers. Data from the agricultural policy information system of Switzerland was used as basis for the calculation. This database contains information on livestock numbers, the crops grown, and the direct payments received for each farm. This information was supported with different data sources from federal offices, cantons, agricultural associations, and research institutions. Balances were calculated as a soil-surface balance according to the OECD method, which includes N input via organic and mineral fertilizers, biological N-fixation, atmospheric N-deposition, and seedlings as well as N outputs via plant yields.The regional balances showed a high variability, resulting in an average N surplus of around 105 kg N per hectare of utilized agricultural area in cantons with highly intensive livestock farming and around 16 kg N in cantons with more extensive farming practices, i.e. in mountain regions. On national scale, highest N input occurred via organic fertilizers, whereas mineral fertilizers and biological N-fixation account for around 15% of the total input each.Our approach of calculating N balances on farm level for the whole Swiss farming system has some limitations, which are mainly due to missing or incomplete data sources. As an example, the use of mineral fertilizers had to be estimated by application data of a rather small sample of farms (~300 farms). Nevertheless, the obtained results show that this methodology is a promising tool to gain a regional overview of the environmental status of Swiss farms. Over the years, this approach will be refined and new data (e.g. additional administrative data, satellite data) can be incorporated in order to better estimate the N balances of Swiss farms.

As the dominant mode of deforestation in the Congo Basin, shifting agriculture is expected to increase with the projected four-fold population growth for the region by 2,100. To assess how this land-use change will affect the export of carbon (C) to rivers in a typical lowland forest ecosystem, we studied paired watersheds near Kisangani, Democratic Republic of the Congo. Two streams, one draining an intact forest (Forest) and one draining an agricultural landscape (Ag), were gauged, equipped with sensors, and sampled fortnightly for one year. Annual average specific discharge was 1.4 mm d-1 (+76%) higher in the Ag compared to the Forest. Average annual dissolved organic C (DOC) and particulate organic C (POC) concentrations were 5.2 mg L-1 (+163%) and 1.3 mg L-1 (+81%) higher in the Ag stream, which, along with the higher discharge, resulted in 8.3 (+410%) and 2.4 g C m-2 yr-1 (+97%) larger C yields, respectively. Baseflow dissolved inorganic carbon, carbon dioxide, and methane yields were also higher in the Ag stream. Despite the higher yields of organic C (OC), the composition of OC did not differ significantly. Carbon to nitrogen ratios, along with isotopic signatures, revealed that both streams contained young, semi-degraded organic matter derived from C3 vegetation. Correspondingly, biodegradable DOC (BDOC) proportions did not differ between the streams, although the Ag stream yielded more total BDOC. These results show that agricultural land-use likely exports a greater proportion of Net Primary Productivity (NPP) to aquatic ecosystems, which may affect both C storage in soils and the proportion of gross PP that is ultimately respired. Shifting agriculture, which is the main way forests are cleared in the Congo Basin, is expected to increase as the population grows. To see how this type of deforestation affects the amount of carbon that ends up in rivers, we studied two types of watersheds: one with only forest and one with mostly farms. We measured the water flow and carbon levels in streams draining these watersheds for a year. We found that the stream draining the farmed area had more water and more carbon compared to the forest stream. This means that more carbon from plants and soil was being washed into the farm stream. The carbon in both streams came from similar sources: partially broken-down plants and topsoil that were recently grown or formed, respectively. The farm stream had a bit more carbon that could break down further once it entered the stream. These findings tell us that farming sends more plant matter and carbon into rivers. This could affect how much carbon is stored in the soil and how much goes back into the air. Streams draining agricultural land-use in Congo lowlands exhibited higher water and organic carbon yields The composition and inferred sources of organic carbon did not differ between forest and agricultural streams Low intensity shifting agriculture in Congo lowlands thus exports a high proportion of net primary productivity downstream

This paper provides causal evidence on the effect of credit crunches on political polarization. We combine data on bank-firm connections and electoral outcomes at the city-level during the 2008-2014 Spanish Financial Crisis. First, we show that firms in a relationship with weak banks experience a reduction in their loan supply and employment growth. Next, we estimate the effects of unemployment on voting behaviour. We construct an instrument for unemployment based on the city-level exposure to foreign weak banks. We find that a one standard deviation increase in instrumented unemployment translates into a 7 percentage increase in the polarisation of voters

ABSTRACT The Ruki is a pristine blackwater tributary in the Congo Basin draining tropical lowland forest. Daily discharge and fortnightly concentrations, isotopic ratios, and molecular composition of carbon and organic matter were measured for 1 yr (2019–2020). Like the Congo River, discharge peaked from November–January, with a smaller secondary peak in June. Dissolved organic carbon (DOC), inorganic carbon (DIC), carbon dioxide ( p CO 2 ), and methane ( p CH 4 ) concentrations were high (21.3 ± 4.8 mg C L −1 , 5.8 ± 0.9 mg C L −1 , 6370 ± 1740 ppm, and 250 ± 100 ppm, respectively) and positively correlated with discharge, indicating transport limitation. Total suspended solids and particulate organic carbon (POC) concentrations were generally low (3.68 ± 1.61 mg L −1 , 0.88 ± 0.33 mg C L −1 , respectively) and varied inversely with discharge, indicating source limitation. The Ruki exported a total of 3.25 Tg C yr −1 , of which DOC, DIC, and POC comprised 76%, 20%, and 3%, respectively. This DOC flux represents ~ 20% of the annual Congo Basin flux from about 5% of its area, highlighting the high yield. Isotopic ratios of DOC and POC indicate modern C3 forest vegetation as a source, except for a few older samples potentially indicating peat inputs. The bulk molecular composition of dissolved organic matter was seasonally consistent; however, a more oxidized and aromatic assemblage occurred at high discharge, corresponding with forest vegetation, while a more aliphatic, nitrogen‐, and sulfur‐enriched assemblage was found during low discharge, corresponding with soil‐derived organic matter. Overall, these results underscore how hydrology controls C concentrations in the Ruki River and how this blackwater river contributes disproportionately to C export per unit area within the Congo Basin hydrosystem.

This paper analyzes how small-firm employment responds to labor productivity risk. We use highly granular data about firms employing workers whose productivity depends on the weather. This allows us to analyze the effects of exogenous fluctuations in labor productivity risk, induced by weather risk. We find that the risk reduces the firms' employment, with a stronger effect on the firms in locations where the regional banks have relatively little equity capital. We also find that, in these locations, the banks' borrowers receive less liquidity from their banks if the locations are subject to adverse weather shocks. It appears that bank capitalization affects small firms' capacity to take labor productivity risk by changing their access to liquidity "insurance". Well-capitalized banks support economic adaptation to weather-induced labor productivity risk.

Globally, tropical forests are assumed to be an important source of atmospheric nitrous oxide (N 2 O) and sink for methane (CH 4 ). Yet, although the Congo Basin comprises the second largest tropical forest and is considered the most pristine large basin left on Earth, in situ N 2 O and CH 4 flux measurements are scarce. Here, we provide multi-year data derived from on-ground soil flux ( n = 1558) and riverine dissolved gas concentration ( n = 332) measurements spanning montane, swamp, and lowland forests. Each forest type core monitoring site was sampled at least for one hydrological year between 2016 - 2020 at a frequency of 7-14 days. We estimate a terrestrial CH 4 uptake (in kg CH 4 -C ha −1 yr −1 ) for montane (−4.28) and lowland forests (−3.52) and a massive CH 4 release from swamp forests (non-inundated 2.68; inundated 341). All investigated forest types were a N 2 O source (except for inundated swamp forest) with 0.93, 1.56, 3.5, and −0.19 kg N 2 O-N ha −1 yr −1 for montane, lowland, non-inundated swamp, and inundated swamp forests, respectively.

Raw chemical and stream data from the publication 'Substantial organic and particulate nitrogen and phosphorus export from geomophologically stable African tropical forest landscapes'. Data shows dissolved and particulate nitrogen and phosphorus concentrations of stream waters of two forested first order streams withing the Congo Basin.

Secondary forests constitute an increasingly important component of tropical forests worldwide. Although cycling of essential nutrients affects recovery trajectories of secondary forests, the effect of nutrient limitation on forest regrowth is poorly constrained. Here we use three lines of evidence from secondary forest succession sequences in central Africa to identify potential nutrient limitation in regrowing forests. First, we show that atmospheric phosphorus supply exceeds demand along forest succession, whereas forests rely on soil stocks to meet their base cation demands. Second, soil nutrient metrics indicate that available phosphorus increases along the succession, whereas available cations decrease. Finally, fine root, foliar and litter stoichiometry show that tissue calcium concentrations decline relative to those of nitrogen and phosphorus during succession. Taken together, these observations suggest that calcium becomes an increasingly scarce resource in central African forests during secondary succession. Furthermore, ecosystem calcium storage shifts from soil to woody biomass over succession, making it a vulnerable nutrient in the wake of land-use change scenarios that involve woody biomass export. Our results thus call for a broadened focus on elements other than nitrogen and phosphorus regarding tropical forest biogeochemical cycles and identify calcium as a scarce and potentially limiting nutrient in an increasingly disturbed and dynamic tropical forest landscape.

Studies on sediment export from tropical forest watersheds are scarce. Of the assessments that do exist, most are of larger rivers or are model-based and lack validation with measured data. Understanding the mechanisms of sediment export dynamics in forested headwaters is important for assessing downstream effects and as a base-line for net impacts of land-use change. To that end, we quantified annual total suspended sediment (TSS) yields in forested headwater catchments of two major forest types in central Africa (tropical lowland forest and sub-tropical Miombo woodland) and analyzed turbidity-discharge hysteresis over one hydrological year. We measured TSS yields of 0.24 +/- 0.09 t ha(-1) yr(-1) in the Miombo woodland and 0.25 +/- 0.05 t ha(-1) yr(-1 )in the lowland forest catchment. The Miombo woodland experienced similar TSS yields as the lowland forest despite a shorter, five-month, rainy season and lower annual precipitation. In the Miombo forest, sparser vegetation cover, seasonal fires that remove understory vegetation and high rainfall intensity during the rainy season therefore resulted in similar TSS yields. As a result of these differences in vegetation and rainfall, approximately 68% of TSS was exported during storm events in the Miombo woodland and 30% in the lowland forest. Both sites showed mainly clockwise hysteresis (positive hysteresis index) patterns of sediment export. In the Miombo woodland, the hysteresis index (i.e., the magnitude and direction of hysteresis) increased with the ongoing rainy season, indicating source limitation already after one month of rain. In the lowland forest, the predominant clockwise hysteresis was more likely caused by the increasing contribution of baseflow during the falling limb of an event, whereas during the rising limb there isa quick flushing of surface material available in the forest. These findings based on hysteresis analysis were further supported by C:N ratio and delta C-13 analyses of particulate organic matter (POM). POM C:N ratios increased and delta C-13 signatures decreased with increased discharge in the lowland forest, indicating the mobilization of topsoil sediments during rain events. In contrast, the Miombo exhibited no shifts in C:N ratios nor in the delta C-13 signature. Despite the pristine nature of these forests and their assumed negligible sediment yields, our results demonstrate that erosion is a significant loss process in tropical forests and call for future research to examine its role in forest functioning and biogeochemical cycling. (C)& nbsp;2021 Elsevier B.V. All rights reserved.

Primary tropical forests generally exhibit large gaseous nitrogen (N) losses, occurring as nitric oxide (NO), nitrous oxide (N 2 O) or elemental nitrogen (N 2 ). The release of N 2 O is of particular concern due to its high global warming potential and destruction of stratospheric ozone. Tropical forest soils are predicted to be among the largest natural sources of N 2 O; however, despite being the world’s second-largest rainforest, measurements of gaseous N-losses from forest soils of the Congo Basin are scarce. In addition, long-term studies investigating N 2 O fluxes from different forest ecosystem types (lowland and montane forests) are scarce. In this study we show that fluxes measured in the Congo Basin were lower than fluxes measured in the Neotropics, and in the tropical forests of Australia and South East Asia. In addition, we show that despite different climatic conditions, average annual N 2 O fluxes in the Congo Basin’s lowland forests (0.97 ± 0.53 kg N ha −1 year −1 ) were comparable to those in its montane forest (0.88 ± 0.97 kg N ha −1 year −1 ). Measurements of soil pore air N 2 O isotope data at multiple depths suggests that a microbial reduction of N 2 O to N 2 within the soil may account for the observed low surface N 2 O fluxes and low soil pore N 2 O concentrations. The potential for microbial reduction is corroborated by a significant abundance and expression of the gene nosZ in soil samples from both study sites. Although isotopic and functional gene analyses indicate an enzymatic potential for complete denitrification, combined gaseous N-losses (N 2 O, N 2 ) are unlikely to account for the missing N-sink in these forests. Other N-losses such as NO, N 2 via Feammox or hydrological particulate organic nitrogen export could play an important role in soils of the Congo Basin and should be the focus of future research.

Nitrogen (N) availability can be highly variable in tropical forests on regional and local scales. While environmental gradients influence N cycling on a regional scale, topography is known to affect N availability on a local scale. We compared natural abundance of 15N isotopes of soil profiles in tropical lowland forest, tropical montane forest, and subtropical Miombo woodland within the Congo Basin as a proxy to assess ecosystem-level differences in N cycling. Soil δ15N profiles indicated that N cycling in the montane forest is relatively more closed and dominated by organic N turnover, whereas the lowland forest and Miombo woodland experienced a more open N cycle dominated by inorganic N. Furthermore, we examined the effect of slope gradient on soil δ15N within forest types to quantify local differences induced by topography. Our results show that slope gradient only affects the soil δ15N in the Miombo forest, which is prone to erosion due to a lower vegetation cover and intense rainfall at the onset of the wet season. Lowland forest, on the other hand, with a flat topography and protective vegetation cover, showed no influence of topography on soil δ15N in our study site. Despite the steep topography, slope angles do not affect soil δ15N in the montane forest, although stable isotope signatures exhibited higher variability within this ecosystem. A pan-tropical analysis of soil δ15N values (i.e., from our study and literature) reveals that soil δ15N in tropical forests is best explained by factors controlling erosion, namely mean annual precipitation, leaf area index, and slope gradient. Erosive forces vary immensely between different tropical forest ecosystems, and our results highlight the need for more spatial coverage of N cycling studies in tropical forests, to further elucidate the local impact of topography on N cycling in this biome. Published by Copernicus Publications on behalf of the European Geosciences Union. 84 S. Baumgartner et al.: Soil 15N signatures of the Congo Basin

Central African tropical forests face increasing anthropogenic pressures, particularly in the form of deforestation and land-use conversion to agriculture. The long-term effects of this transformation of pristine forests to fallow-based agroecosystems and secondary forests on biogeochemical cycles that drive forest functioning are poorly understood. Here, we show that biomass burning on the African continent results in high phosphorus (P) deposition on an equatorial forest via fire-derived atmospheric emissions. Furthermore, we show that deposition loads increase with forest regrowth age, likely due to increasing canopy complexity, ranging from 0.4 kg P ha −1 yr −1 on agricultural fields to 3.1 kg P ha −1 yr −1 on old secondary forests. In forest systems, canopy wash-off of dry P deposition increases with rainfall amount, highlighting how tropical forest canopies act as dynamic reservoirs for enhanced addition of this essential plant nutrient. Overall, the observed P deposition load at the study site is substantial and demonstrates the importance of canopy trapping as a pathway for nutrient input into forest ecosystems.

In the Lake Kivu region, water erosion is the main driver for soil degradation, but observational data to quantify the extent and to assess the spatial-temporal dynamics of the controlling factors are hardly available. In particular, high spatial and temporal resolution rainfall data are essential as precipitation is the driving force of soil erosion. In this study, we evaluated to what extent high temporal resolution data from the TAHMO network (with poor spatial and long-term coverage) can be combined with low temporal resolution data (with a high spatial density covering long periods of time) to improve rainfall erosivity assessments. To this end, 5 minute rainfall data from TAHMO stations in the Lake Kivu region, representing ca. 37 observation-years, were analyzed. The analysis of the TAHMO data showed that rainfall erosivity was mainly controlled by rainfall amount and elevation and that this relation was different for the dry and wet season. By combining high and low temporal resolution databases and a set of spatial covariates, an environmental regression approach (GAM) was used to assess the spatiotemporal patterns of rainfall erosivity for the whole region. A validation procedure showed relatively good predictions for most months (R2 between 0.50 and 0.80), while the model was less performant for the wettest (April) and two driest months (July and August) (R2 between 0.24 and 0.38). The predicted annual erosivity was highly variable with a range between 2000 and 9000 MJ mm ha−1 h−1 yr−1 and showed a pronounced east–west gradient which is strongly influenced by local topography. This study showed that the combination of high and low temporal resolution rainfall data and spatial prediction models can be used to improve the assessments of monthly and annual rainfall erosivity patterns that are grounded in locally calibrated and validated data.

Soil respiration is an important carbon flux and key process determining the net ecosystem production of terrestrial ecosystems. To address the lack of quantification and understanding of seasonality in soil respiration of tropical forests in the Congo Basin, soil CO2 fluxes and potential controlling factors were measured annually in two dominant forest types (lowland and montane) of the Congo Basin over 2 years at varying temporal resolution. Soil CO2 fluxes from the Congo Basin resulted in 3.45 ± 1.14 and 3.13 ± 1.22 µmol CO2 m−2 s−1 for lowland and montane forests, respectively. Soil CO2 fluxes in montane forest soils showed a clear seasonality with decreasing flux rates during the dry season. Montane forest soil CO2 fluxes were positively correlated with soil moisture, while CO2 fluxes in the lowland forest were not. Smaller differences of δ13C values of leaf litter, soil organic carbon (SOC), and soil CO2 indicated that SOC in lowland forests is more decomposed than in montane forests, suggesting that respiration is controlled by C availability rather than environmental factors. In general, C in montane forests was more enriched in 13C throughout the whole cascade of carbon intake via photosynthesis, litterfall, SOC, and soil CO2 compared to lowland forests, pointing to a more open system. Even though soil CO2 fluxes are similarly high in lowland and montane forests of the Congo Basin, the drivers of them seem to be different, i.e., soil moisture for montane forest and C availability for lowland forest.