Forest Dynamics
Seed dispersal strategies and the threat of defaunation in a Congo forestBackgroundSeed dispersal plays a critical role in shaping plant communities and maintaining biodiversity in tropical forests. In the Congo Basin, most tree species depend on animals (zoochory) to disperse their seeds, with large vertebrates such as forest elephants and bonobos serving as key dispersers. However, hunting and poaching threaten these animals, potentially triggering cascading effects on forest structure and plant regeneration. This study investigates the extent of animal-mediated seed dispersal in the LuiKotale forest in the Democratic Republic of the Congo (DRC) and evaluates how hunting pressure on frugivores may influence tree community composition. Available with subscription or purchase |
Drivers and spatial patterns of avian defaunation in tropical forestsBackgroundTropical forests harbor an immense diversity of bird species, but hunting and wildlife trade are driving widespread declines in bird populations. Unlike habitat loss, hunting often occurs in seemingly intact forests, making its impact more difficult to detect. Birds are harvested for both subsistence (food) and commercial purposes (pet trade), but the spatial extent and drivers of avian defaunation remain poorly understood. This study aims to assess the factors influencing bird population declines and map defaunation patterns across tropical forests. Open access copy available |
Using Janzen–Connell to predict the consequences of defaunation and other disturbances of tropical forestsBackgroundThe Janzen–Connell (J–C) model describes how seed dispersal and mortality shape tropical forest diversity. According to the model, seeds that fall close to their parent trees suffer high mortality due to host-specific predators, pathogens, and herbivores. In contrast, seeds dispersed farther away have a better chance of survival. Defaunation, particularly the loss of large-bodied seed dispersers, disrupts this balance by reducing seed dispersal distances. This study applies the J–C model to predict how defaunation and other disturbances affect tree recruitment and forest composition. Available with subscription or purchase |
Cascading effects of contemporaneous defaunation on tropical forest communitiesBackgroundDefaunation, caused by hunting and habitat fragmentation, is a major threat to biodiversity in tropical forests. It disproportionately affects large-bodied vertebrates, which play key roles as seed dispersers, seed predators, and herbivores. The loss of these animals can have cascading effects on plant populations, altering species composition, seed dispersal, and plant recruitment. This study reviews empirical evidence from 42 studies to understand how defaunation influences plant-animal interactions, plant demography, and overall community diversity. Available with subscription or purchase |
Complementary ecosystem services from multiple land uses highlight the importance of tropical mosaic landscapesBackgroundTropical agricultural landscapes feature a mosaic of diverse land uses, yet the ecosystem service bundles and materials they provide to rural households remain poorly understood. In northeastern Madagascar, shifting cultivation for hillside rice production and agroforests for cash and subsistence crops have largely replaced old-growth forests. The landscape consists of forest fragments, small-scale vanilla agroforests, rice paddies, and subsistence farming plots at various stages of the shifting cultivation cycle. Open access copy available |
Forest concessions in the Maya Biosphere Reserve, Guatemala: A decade laterBACKGROUND:Over the past few decades, there has been a significant shift in conservation strategies from traditional command-and-control approaches to more inclusive, community-focused philosophies. This transition was driven by the recognition of the failures of strict protectionism, which often led to diminished ecological and institutional resilience. Simultaneously, the recognition of rural communities as both impacted by and impactful within natural systems has grown, advocating for incentive-based, participatory strategies to address human-environment conflicts effectively. Available with subscription or purchase |
Nitrogen Fixing Trees for Animal Production on Acid SoilsBackgroundNitrogen-fixing trees play a crucial role in improving pasture and livestock systems on acid soils, which are prevalent in tropical regions. Acid soils often challenge agricultural productivity due to low fertility and high aluminum toxicity. Nitrogen-fixing trees, such as Erythrina poeppigiana, Cratylia argentea, and Alnus acuminata, enhance soil chemistry and fertility by adding nitrogen through organic matter and improving physical soil properties like porosity and bulk density. They are integrated into silvopastoral systems, where trees and shrubs coexist with pastures, offering multiple benefits such as soil stabilization, increased forage quality, and diversified farm outputs. Open access copy available |
Alnus acuminata: Valuable Timber Tree for Tropical HighlandsBackgroundAlnus acuminata, also known as alder, is a nitrogen-fixing tree native to tropical highlands from Mexico to northern Argentina. It thrives in elevations between 1,200 and 3,200 meters, with annual rainfall of 1,000 to 3,000 mm and temperatures ranging from 4°C to 27°C. This species plays a significant role in watershed protection, soil enrichment, and sustainable timber production. Its adaptability to moist soils, including riverbanks and landslides, and its resilience in disturbed areas make it a valuable pioneer species. Farmers in regions like Costa Rica have used Alnus acuminata in agroforestry systems for over 90 years, integrating it with pastureland and coffee cultivation. Open access copy available |
Biodiversity conservation in Costa Rica: a correspondence analysis between identifi ed biodiversity hotspots (Araceae, Arecaceae, Bromeliaceae, and Scarabaeinae) and conservation priority life zonesBackgroundOpen access copy available |
Evaluating alder-endophyte (Alnus acuminata-Frankia-Mycorrhizae) interactionsBackgroundThe study examines the interactions between Alnus acuminata (a nitrogen-fixing tree), Frankia (a nitrogen-fixing actinomycete), and vesicular-arbuscular mycorrhizae (VAM), specifically Glomus intra-radices. These symbiotic relationships are significant in upland areas of Costa Rica, Colombia, and Venezuela, where A. acuminata grows alongside pastures. Frankia forms root nodules that fix atmospheric nitrogen, while VAM enhances phosphorus uptake, crucial for plant growth in nutrient-poor soils. The study aims to understand the effects of these interactions on nitrogen fixation and seedling development under varying phosphorus levels. Available with subscription or purchase |
