Publications by authors named "Aida Cuni Sanchez"

Background: Pastoralists' sedentarisation and agriculturalisation might increase their vulnerability to climate change impacts, but few studies have investigated if this is the case in mountain areas. In Uganda, little is known about how Sebei pastoralists have perceived and adapted to such changes. This study sought to establish perspectives of Sebei pastoralists on climate change in terms of its occurrence and impacts as well as access to livelihood assets and or opportunities to withstand such challenges.

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Thermophilization is the directional change in species community composition towards greater relative abundances of species associated with warmer environments. This process is well-documented in temperate and Neotropical plant communities, but it is uncertain whether this phenomenon occurs elsewhere in the tropics. Here we extend the search for thermophilization to equatorial Africa, where lower tree diversity compared to other tropical forest regions and different biogeographic history could affect community responses to climate change.

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Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge.

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Article Synopsis
  • The latitudinal diversity gradient (LDG) reflects a global trend showing that species richness typically increases towards the tropics, but understanding its causes has been challenging due to insufficient data.
  • A new high-resolution map of local tree species richness was created using extensive global forest inventory data and local biophysical factors, analyzing around 1.3 million sample plots.
  • Findings indicate that annual mean temperature is a significant predictor of tree species richness, aligning with the metabolic theory of biodiversity, but additional local factors also play a crucial role, especially in tropical regions.
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Mountain environments experience more rapid changes in temperature than lower elevations. However, little is known about the climatic changes already observed in African mountains, or the adaptation strategies used by hunter-gatherer communities. Semi-structured interviews were administered to 100 Twa hunter-gatherers living around Mt Kahuzi in eastern Democratic Republic of the Congo (DR Congo).

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  • - The study highlights how environmental exposure to active pharmaceutical ingredients (APIs) can harm ecosystems and human health, indicating the need for a comprehensive assessment of this global issue.
  • - Conducted across 258 rivers in 104 countries, the research found notably high levels of API contamination in sub-Saharan Africa, South Asia, and South America, often linked to poor waste management and pharmaceutical production practices.
  • - Over 25% of the sampling sites had API concentrations exceeding safe levels for aquatic life, raising concerns about environmental risks and the potential for increased antimicrobial resistance, which threatens progress toward the United Nations Sustainable Development Goals.
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  • * A study analyzing 44 montane sites across 12 African countries reveals that the average aboveground live tree biomass carbon (AGC) stock is 149.4 megagrams of carbon per hectare, which is higher than similar forests in the Neotropics and above default values set by the Intergovernmental Panel on Climate Change.
  • * Despite this carbon richness, African montane forests face threats, having lost about 0.8 million hectares of old-growth forest since 2000, emphasizing the need for conservation efforts to protect
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The responses of tropical forests to environmental change are critical uncertainties in predicting the future impacts of climate change. The positive phase of the 2015-2016 El Niño Southern Oscillation resulted in unprecedented heat and low precipitation in the tropics with substantial impacts on the global carbon cycle. The role of African tropical forests is uncertain as their responses to short-term drought and temperature anomalies have yet to be determined using on-the-ground measurements.

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Background: Mangrove forests have gained recognition for their potential role in climate change mitigation due to carbon sequestration in live trees, and carbon storage in the sediments trapped by mangrove tree roots and pneumatophores. Africa hosts about 19% of the world's mangroves, yet relatively few studies have examined the carbon stocks of African mangroves. The available studies report considerable differences among sites and amongst the different pools of carbon stocks.

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  • The study highlights the uncertainty in how tropical forests' carbon storage responds to climate change, particularly the effects of long-term drying and warming.
  • Analysis of 590 permanent plots across the tropics finds that maximum temperature significantly reduces aboveground biomass, affecting carbon storage more in hotter forests.
  • The results indicate that tropical forests have greater resilience to temperature changes than short-term studies suggest, emphasizing the need for forest protection and climate stabilization for long-term adaptation.
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  • Structurally intact tropical forests contributed significantly to global carbon sequestration in the 1990s and early 2000s, absorbing about 15% of human-caused CO2 emissions.
  • A study comparing African and Amazonian forests found that while African forests have maintained a stable carbon sink over three decades, Amazonian forests are experiencing a long-term decline in carbon absorption due to increased tree mortality.
  • Recent trends suggest a potential increase in carbon losses in African forests post-2010, indicating that both regions are facing different challenges regarding their carbon sinks and may experience declines in the future.
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Forest biomass is an essential indicator for monitoring the Earth's ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (AGB) is now possible with satellite remote sensing (RS).

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  • Understanding how forests store carbon is important for climate change!
  • Scientists studied the age of carbon in different parts of African tropical forests and found that smaller understory trees hold carbon longer than taller trees!
  • This means we need to pay more attention to all parts of the forest for better conservation and carbon tracking!
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  • The study examines land cover changes in the Fazao-Malfakassa National Park, the largest in Togo, focusing on vegetation degradation and fragmentation due to human activities from 1987 to 2015.
  • It uses remote sensing data and interviews with local populations to identify key drivers of change, including agricultural expansion, bush fires, and illegal timber extraction.
  • The findings underline the urgency for management interventions to protect this vital habitat and the biodiversity it supports, while also drawing on successful strategies from similar regions.
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There has been an increasing interest in fodder trees and their potential to help the rural poor. However, few studies have addressed the ecological impacts of fodder tree harvesting. We investigated the species harvested and the techniques used, and the effects of fodder harvesting on (1) species' populations and (2) forest carbon stocks in three montane forests in Kenya.

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Quantifying the relationship between tree diameter and height is a key component of efforts to estimate biomass and carbon stocks in tropical forests. Although substantial site-to-site variation in height-diameter allometries has been documented, the time consuming nature of measuring all tree heights in an inventory plot means that most studies do not include height, or else use generic pan-tropical or regional allometric equations to estimate height.Using a pan-tropical dataset of 73 plots where at least 150 trees had in-field ground-based height measurements, we examined how the number of trees sampled affects the performance of locally derived height-diameter allometries, and evaluated the performance of different methods for sampling trees for height measurement.

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Tropical montane forests provide an important natural laboratory to test ecological theory. While it is well-known that some aspects of forest structure change with altitude, little is known on the effects of altitude on above ground biomass (AGB), particularly with regard to changing height-diameter allometry. To address this we investigate (1) the effects of altitude on height-diameter allometry, (2) how different height-diameter allometric models affect above ground biomass estimates; and (3) how other forest structural, taxonomic and environmental attributes affect above ground biomass using 30 permanent sample plots (1-ha; all trees ≥ 10 cm diameter measured) established between 1250 and 2600 m asl in Kahuzi Biega National Park in eastern Democratic Republic of Congo.

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Tropical forests are global centres of biodiversity and carbon storage. Many tropical countries aspire to protect forest to fulfil biodiversity and climate mitigation policy targets, but the conservation strategies needed to achieve these two functions depend critically on the tropical forest tree diversity-carbon storage relationship. Assessing this relationship is challenging due to the scarcity of inventories where carbon stocks in aboveground biomass and species identifications have been simultaneously and robustly quantified.

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Tropical forests currently play a key role in regulating the terrestrial carbon cycle and abating climate change by storing carbon in wood. However, there remains considerable uncertainty as to whether tropical forests will continue to act as carbon sinks in the face of increased pressure from expanding human activities. Consequently, understanding what drives productivity in tropical forests is critical.

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Recent studies show widespread encroachment of forest into savannas with important consequences for the global carbon cycle and land-atmosphere interactions. However, little research has focused on in situ measurements of the successional sequence of savanna to forest in Africa. Using long-term inventory plots we quantify changes in vegetation structure, above-ground biomass (AGB) and biodiversity of trees ≥10 cm diameter over 20 years for five vegetation types: savanna; colonising forest (F1), monodominant Okoume forest (F2); young Marantaceae forest (F3); and mixed Marantaceae forest (F4) in Lopé National Park, central Gabon, plus novel 3D terrestrial laser scanning (TLS) measurements to assess forest structure differences.

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