Search Results (5)

Bidens pilosa L. is a cosmopolitan and invasive weed that strongly impacts agricultural systems in tropical regions. In Veracruz, Mexico, its presence extends mainly across mid-elevation zones where coffee, maize, and sugarcane are cultivated. This study characterized the bioclimatic and edaphic determinants of B. pilosa distribution using 581 georeferenced occurrences combined with 19 bioclimatic variables, elevation, and soil data. A Maxent model revealed the highest habitat suitability (0.65–1.0) in the central mountainous region between 800 and 1500 m.a.s.l., particularly under temperate–humid climates (Cfa, Cfb) and Acrisol–Leptosol soils. Principal component and redundancy analyses showed that annual precipitation (BIO12), precipitation of the driest month (BIO14), and temperature seasonality (BIO4) explained 74.7% of the total environmental variance. Cluster analysis identified four distinct ecological groups, confirming broad ecological plasticity. These findings indicate that B. pilosa is not randomly distributed but structured along climatic and soil gradients, with precipitation and elevation as major determinants of its ecological niche. Understanding these relationships provides a quantitative framework for predicting its expansion under future climate scenarios and for designing targeted management strategies in tropical agroecosystems. Full article

Eucalyptus is the main fast-growing tree for biomass production in the tropics, providing resources for pulp and paper industries and bioenergy. The potential productivity of forest sites over an eight-year rotation in Brazil was evaluated by the Physiological Principles in Predicting Growth (3-PG) model for two soils, Acrisols and Arenosols, with high and low water storage, respectively, and distinct productive potential capacity. The model was parameterized by data-sets obtained in bimonthly forest inventories performed in stands with 33, 58 and 89 months-old trees, and edaphic surveys. The average volumetric productivity of wood and biomass of the main stem determined at the 89 months-old stand was 374 m³ ha⁻¹ (177 Mg ha⁻¹) for Acrisols and 272.3 m³ ha⁻¹ (130.0 Mg ha⁻¹) for Arenosols. The estimated volumetric production in the Arenosols had a high mean annual increment up to the age of 58 months, with a significant reduction in growth rates after this time. In Acrisols, high incremental rates in wood volume up to age of 89 months (MAI_VW > 50 m³ ha⁻¹ year⁻¹) indicate that, under ideal soil conditions, the cutting cycle may exceed 8 years with no productivity impairment. The parameterized model matched well for forest yield (r² > 0.9) and dendrometric variables (r² > 0.78). The expected results of lower productivity in Arenosols occurred only after 58 months, while for Acrisols productivity remained high up to 89 months. The results showed the eucalyptus cycle should be shorter in Arenosols, since the lower cutting cycle can provide higher final productivity, when using the mean annual increment to evaluate productivity. Full article

Tropical forests play an important role in carbon storage, accumulating large amounts of carbon in their aboveground and belowground components. However, anthropogenic land-use activities have increasingly threatened tropical forests, resulting in accelerated global greenhouse gas emissions. This research aimed to estimate the carbon stocks in soil, organic layer, and litterfall in tropical montane forests under three different land uses (intact forest, logged-over forest, and plantation forest) at Long Mio, Sabah, Malaysia. Field data were collected in a total of 25 plots from which soil was randomly sampled at three depths. Litterfalls were collected monthly from November 2018 to October 2019. The results showed that the soil in the study area is Gleyic Acrisol, having pH values ranging between 4.21 and 5.71, and high soil organic matter contents. The results also showed that the total soil carbon stock, organic layer, and litterfall is higher in the intact forest (101.62 Mg C ha⁻¹), followed by the logged-over forest (95.61 Mg C ha⁻¹) and the plantation forest (93.30 Mg C ha⁻¹). This study highlights the importance of conserving intact forests as a strategy to sequester carbon and climate change mitigation. Full article

Rangeland management in former tropical rainforest areas may affect ecosystem services. We hypothesized that management practices like burning and overgrazing reduce supporting (soil quality) and consequently also provisioning (forage productivity and quality) and regulating (nutrient cycling) ecosystem services. We established 31 exclosures in two landscape categories (alluvial soils, low-hills), documented management practices, and assessed 18 soil quality indicators, litter decomposition as a proxy for nutrient cycling, and forage quantity and quality during one year in grasslands of the Lacandon region, southeast Mexico. Path analysis was used to explore direct and indirect effects of livestock management practices on soil-based ecosystem services. Landscape position had direct effects on management practices, and direct and indirect effects on soil properties. Altitude (a proxy for the soil catena, ranging from alluvial soils along the Lacantún river to Cambisols and Acrisols in the low-hills) was the variable showing most significant negative relations with soil quality and forage production. Decomposition rate was site-specific and had no relation with landscape position and management. Our study suggests that position on the landscape, which relates to nutrient and water availability, had stronger effects than management practices on forage productivity and quality and drives farmers management practices. Full article

A laboratory microcosm incubation was conducted to study the influence of mixed cowpea-maize residues on N₂O emission and N mineralization in a tropical acrisol. The soils were incorporated with different ratios of cowpea:maize mixtures on weight basis: 100:0, 75:25, 50:50, 25:75 and 0:100, and a control treatment in which there was no residue incorporation. The results show that N₂O and CO₂ emissions were higher in the sole cowpea treatment (100:0) than the sole maize treatment (0:100) and the control. However, cowpea-maize residue mixtures increased the proportion of N lost as N₂O compared to the sole treatments. This interactive effect was highest in the 75:25 treatment. The 50:50 treatment showed moderate N₂O emission compared to the 100:0, 75:25 and 25:75 treatments but with corresponding steady N mineralization and appreciable mineral N concentration. It is concluded that mixing cowpea-maize residues might increase the proportion of N lost as N₂O in a tropical acrisol. However, compared to the other residue mixture treatments, mixing cowpea-maize residues in equal proportions on weight basis might offer a path to reducing N₂O emissions while maintaining a steady N mineralization without risking good N supply in acrisols. The study therefore offers potential for mitigating greenhouse gas emissions while maintaining soil fertility in tropical acrisols. However, further studies under both laboratory and field conditions will be required to verify and validate this claim. Full article