Remote sensing (RS) techniques and Geographic Information Systems (GIS) for earth observation have significantly improved the ability to map and measure forest composition, estimate height and biomass, detect degradation and deforestation, implement land use planning, track land use changes as well as monitoring the implementation and respect of land development policies at a finer scale. Machine learning approaches further enhance these capabilities by integrating multiple data sources to produce improved maps of forest attributes and track changes over time. Recent advances in remote sensing techniques and artificial intelligence (AI) now enable detailed mapping and modelling of conservation areas especially the demarcation of High Valued Conservation Forest. National governments follow an administrative procedure for national map design, validation, and standardization. National governments together with the national mapping institutions select particular government officials, the private sector, civil society organizations, and foreign partners to produce national maps. On the other hand, scientists use a rigorous methodology that combines cutting-edge tools and peer review approaches. Even if some of the maps mentioned have not undergone the validation process by the various governments of the sub-region, they are widely used or referred to in international negotiations and discussions. Adopting innovative policies on mapping (Indonesia’s one map policy, Rwanda National land registry) and spatial data management (Geoportal for the Region, The INSPIRE Directive) will be very helpful in planning and conserving the Congo Basin. Non the less, Gabon, the DRC and Cameroon have made exceptions by producing and using renowned National Geoportal.
Tag: biomass
Ten years experience with alley farming in Central America
The first alley cropping trial in Latin America was set up in May of 1982 with Erythrina poeppigiana Walpers O.F. Cook and Gliricidia sepium (Jacq.) WalpMaize, phaseolus beans, and cassava were used as test crops. Bean performance under alley farming was generally superior to maize, significantly outyielding control plots. Although above ground biomass produced by maize was significantly higher under alley farming, maize yield was equivalent to control plots. Starting from 1983, similar trials were set up on farmer’s fields using Gliricidia sepium and a maize-bean rotation. Alley farming generally gave both higher mean maize and bean yields and higher yield stability than controls plots. In 1990 additional alley farming trials farming trials were carried out in Costa Rica and Nicaragua.
New species-specific allometric models for above- and below-ground biomass and carbon content of young mangroves
Mangroves restoration plays a vital role in climate change mitigation, with carbon sequestration capability as a key indicator. However, most existing allometric models used for biomass estimation are developed from mature trees and are unsuitable for young mangroves due to limitations in the availability of predictor variables. These models rely on diameter at breast height (DBH) to predict biomass, making them inapplicable for young mangroves in the early restoration phase, which do not yet have a measurable DBH. This study develops species-specific allometric equations for estimating aboveground (AGB) and belowground biomass (BGB) of young mangroves across four species: Bruguiera gymnorrhiza, Kandelia candel, Rhizophora apiculata, and Rhizophora mucronata. Samples were collected using destructive methods along with structural measurement to develop species-specific allometric models using simple power equation and compared with existing models. Biomass distribution was highest in the stem, followed by branches and stilt-roots, then lowest in roots. Carbon content was relatively uniform among different tree components, except for lower values in roots. AGB proportion generally exceeded BGB, except in R. apiculata, with root-to-shoot ratios ranging from 0.43 to 1.31. The best AGB and BGB models showed high goodness of fit (Adj R² = 0.94–0.95 and 0.83–0.97, respectively). Validation showed species-specific performance varied among AGB models (RMSE = 0.07–0.20; MAPE = 0.15–0.25) and among BGB models (RMSE = 0.04–0.43; MAPE = 0.13–0.40). Compared to existing allometric models for mangrove saplings, these new models enhance biomass estimation accuracy for young mangroves that are essential in restoration monitoring and complement existing equations suited for mature trees. Notably, this study provides the first allometric model for K. candel in Indonesia and includes BGB estimates, which are still limited in mangroves research.
Small persistent humid forest clearings drive tropical forest biomass losses
Tropical forests store about half of the global forest aboveground carbon (AGC)1, yet extensive areas are affected by disturbances, such as deforestation from agricultural expansion2,3 and degradation from fires4, selective logging5, and edge effects6,7. Over time, disturbed forests can recover, gradually restoring carbon stocks and ecological functions8. However, how recovery rates vary with disturbance size, type and location remains poorly quantified. Here we use a bookkeeping approach with spatially explicit vegetation recovery curves to quantify AGC dynamics in disturbed tropical forests during 1990–2020. We find that disturbed tropical dry forests remained carbon neutral, whereas disturbed tropical humid forests experienced a net AGC loss of 15.6 ± 3.7 PgC, primarily driven by small but persistent deforestation clearings. Despite affecting only about 5% of the disturbed area, these small-size (less than 2 ha) deforestation events accounted for about 56% of carbon losses, owing to persistent land-use conversion without forest regrowth. By contrast, large fire-induced carbon losses were offset by the long-term post-fire recovery. Over time, deforestation expanded into humid forests with higher carbon stock density, intensifying AGC losses per unit area. These findings highlight the disproportionate impact of small clearings on tropical carbon losses, suggesting the need to curb land-use changes and protect young and recovering forests.
Interactions between regenerative strategies and edaphic, climatic and topographic factors mediate mitigation or exacerbation of soil and crop toxicity in global cadmium contaminated lands
Cadmium (Cd) contamination in agroecosystems is a global concern, due to its negative influence on soil health and crop performance. Regenerative strategies have been widely recognised as vital to improve soil quality and crop yields. Yet strategies are needed that also mitigate rather than exacerbate the impacts of Cd contamination. In this context, interactions between regenerative strategies, and edaphic, climatic and topographic factors are poorly understood. This study presents a meta-analysis with effect size statistics, evaluating the interactions between regenerative strategies (biochar, manure and compost), non- regenerative strategies (sewage-sludge and fertilizer), soil properties (pH, SOM and Cd levels), climatic factors (temperature and precipitation), and elevation. In acidic or high SOM soils, fertilizer increased Cd uptake by 50% to 76%. However, biochar or compost addition in these soils reduced Cd uptake. Under high Cd contamination, biochar application increased shoot biomass, but fertilizer application decreased shoot-biomass. The application of fertilizer or sewage-sludge under higher temperatures increased Cd uptake, whereas biochar reduced Cd uptake. At wet sites, fertilizer addition increased soil Cd accumulation. At high elevations, biochar was more effective than manure at reducing Cd accumulation. We conclude that there are complex interactions between regenerative strategies and environmental conditions; determining impacts on soil and crop health. The interactions between environmental factors and use of sewage-sludge or fertilizer could exacerbate soil and plant Cd toxicity. Regenerative strategies, especially biochar, could mitigate Cd toxicity in agroecosystems.
Pantropical tree rings show small effects of drought on stem growth
Increasing drought pressure under anthropogenic climate change may jeopardize the potential of tropical forests to capture carbon in woody biomass and act as a long-term carbon dioxide sink. To evaluate this risk, we assessed drought impacts in 483 tree-ring chronologies from across the tropics and found an overall modest stem growth decline (2.5% with a 95% confidence interval of 2.2 to 2.7%) during the 10% driest years since 1930. Stem growth declines exceeded 10% in 25% of cases and were larger at hotter and drier sites and for gymnosperms compared with angiosperms. Growth declines generally did not outlast drought years and were partially mitigated by growth stimulation in wet years. Thus, pantropical forest carbon sequestration through stem growth has hitherto shown drought resilience that may, however, diminish under future climate change.
Early-stage sustainability assessment of greywater treatment with Moringa oleifera seed extract and biochar
Access to safe and reliable water remains a significant challenge in much of the Global South, especially in rural areas where greywater treatment infrastructure is lacking. This study presents an early-stage sustainability assessment of a novel system that utilises biochar and Moringa oleifera seed extracts to treat greywater in rural Kenyan households. The proposed solution combines local biochar, a by-product of wood gasification cookstoves, and powdered Moringa oleifera seed cake, a residue from local agroforestry activities. The presented assessment applied a qualitative approach that integrates life cycle, circular bioeconomy, and sustainable sanitation principles. The key sustainability opportunities involved in the assessed system include improved human health and hygiene, the carbon sequestration potential of biochar, greywater reuse, and efficient use of local biomass resources. However, the system also involves risks related to filter media disposal, nutrient loss and system maintenance. The analysis highlights the trade-offs between using Moringa oleifera seed cake for water purification and animal feed. Moreover, the early-stage assessment identifies the need for pilot trials, participatory design and data collection to develop future life cycle analyses and implementation strategies. This integrated approach provides a sound basis for the sustainable development of natural greywater treatment systems that meet the goals of a circular bioeconomy.
Adaption of some leguminous trees for agroforestry use in the north coast of Colombia
Erythrina berteroana, E. fusca, E. poeppigiana, Gliricidia sepium, Leucaena leucocephala, and Senna siamea [Cassia siamea] were grown for 15 months at two lowland sites in Columbia. Survival, height growth and biomass production (leaves + stems removed in pruning) were determined after 8 and 15 months; prunings removed after 8 months were broadcast over the plot after sampling. Nutrient uptake data are also reported (analysed from prunings). G. sepium and C. siamea performed best, with the other 4 species performing poorly.
Light use efficiency (LUE) based bimonthly gross primary productivity (GPP) for global grasslands at 30 m spatial resolution (2000–2022)
The article describes production of a high spatial resolution (30 m) bimonthly light use efficiency (LUE) based gross primary productivity (GPP) data set representing grasslands for the period 2000 to 2022. The data set is based on using reconstructed global complete consistent bimonthly Landsat archive (400TB of data), combined with 1 km MOD11A1 temperature data and 1° CERES Photosynthetically Active Radiation (PAR). First, the LUE model was implemented by taking the biome-specific productivity factor (maximum LUE parameter) as a global constant, producing a global bimonthly (uncalibrated) productivity data for the complete land mask. Second, the GPP 30 m bimonthly maps were derived for the global grassland annual predictions and calibrating the values based on the maximum LUE factor of 0.86 gCm−2d−1MJ−1. The results of validation of the produced GPP estimates based on 527 eddy covariance flux towers show an R-square between 0.48–0.71 and root mean square error (RMSE) below ~2.3 gCm−2d−1 for all land cover classes. Using a total of 92 flux towers located in grasslands, the validation of the GPP product calibrated for the grassland biome revealed an R-square between 0.51–0.70 and an RMSE smaller than ~2 gCm−2d−1. The final time-series of maps (uncalibrated and grassland GPP) are available as bimonthly (daily estimates in units of gCm−2d−1) and annual (daily average accumulated by 365 days in units of gCm−2yr−1) in Cloud-Optimized GeoTIFF (~23TB in size) as open data (CC-BY license). The recommended uses of data include: trend analysis e.g., to determine where are the largest losses in GPP and which could be an indicator of potential land degradation, crop yield mapping and for modeling GHG fluxes at finer spatial resolution. Produced maps are available via SpatioTemporal Asset Catalog (http://stac.openlandmap.org) and Google Earth Engine.
Balancing livestock free grazing and ecosystem functionality: investigating the carrying capacity of grazing land in the Eastern Savannah of Rwanda
This study focused on investigating the carrying capacity of individual grazing lands in the Eastern Province of Rwanda. We collected data on above-ground biomass of natural pasture from 63 farms during the wet and dry seasons to capture the seasonal variation of forages. Since the grazing system is based on individual farms, we clustered farm size into three clusters, namely ≤ 10.9 ha (small); 11–20.9 ha (medium) and ≥ 21 ha (large). Dry matter and chemical composition of biomass samples was determined. Additionally, as crop residues are a significant feed resource for farmers, we also estimated their production for the year 2023 because of the availability of reliable data over the corresponding two agricultural seasons. Dry matter exhibited significant difference (p < 0.0001) across both farm sizes and seasons. Similarly, crude protein showed significant difference (p < 0.0001) across farm sizes and seasons. The neutral detergent fibre (NDF) showed only significant difference across the seasons (p < 0.0001). Acid detergent fibre (ADF) showed significant difference (p < 0.05) across both farm sizes and seasons. The interaction between farm size and season was significant difference (p < 0.0001) for NDF and ADF (p = 0.0085). Furthermore, the tropical Livestock Unit (TLU), showed that the available biomass in the medium farm could feed only the TLU for a period of 58 days while the small farm could only feed for 42 days whilst the crop residues could meet the dry matter intake of 171,750 TLU annually. The findings suggest the effective crop residue utilization and highlight that proper grazing land management strategies should be applied for optimizing cattle productivity, ensuring sustainability, and climate resilience.