Search Results (28)

Tropical forests continue to experience high levels of habitat loss and degradation, with wildfires becoming a frequent component of human-modified landscapes. Here we investigate the response of palm species to the conversion of old-growth forests to successional mosaics, including forest patches burned during wildfires. Palms (≥50 cm height) were recorded once in 2023–2024, across four habitat classes: terra firme old-growth stands, regenerating forest stands associated with slash-and-burn agriculture, old-growth stands burned once and twice, and active cassava fields, in the Tapajós-Arapiuns Extractive Reserve, in the eastern Brazilian Amazon. The flammability of palm leaf litter and forest litter were also examined to assess the potential connections between palm proliferation and wildfires. A total of 10 palm species were recorded in this social forest (including slash-and-burn agriculture and resulting successional mosaics), with positive, negative, and neutral responses to land use. Species richness did not differ among forest habitats, but absolute palm abundance was greatest in disturbed habitats. Only Attalea spectabilis Mart. (curuá) exhibited increased relative abundance across disturbed habitats, including active cassava field. Attalea spectabilis accounted for almost 43% of all stems in the old-growth forest, 89% in regenerating forests, 90% in burned forests, and 79% in crop fields. Disturbed habitats supported a five-to-ten-fold increment in curuá leaves as a measure of habitat flammability. Although curuá litter exhibited lower flame temperature and height, its lower carbon and higher volatile content is expected to be more sensitive to fire ignition and promote the spread of wildfires. The conversion of old-growth forests into social forests promotes the establishment of palm-dominated forests, increasing the potential for a forest transition further fueled by wildfires, with effects on forest resilience and social reproduction still to be understood. Full article

The intensification of economic globalization and the growing scarcity of global land resources have magnified the complexity of future land use and land cover (LULC) changes. In Mainland Southeast Asia (MSEA), these transformations are particularly pronounced, yet comprehensive, targeted, and systematic reviews are scant. This research employs bibliometrics and critical literature review methodologies to scrutinize 1956 relevant publications spanning from 1990–2023, revealing key insights into the contributors to land use studies in MSEA, which include not only local researchers from countries like Thailand and Vietnam but also international scholars from the United States, China, Japan, and France. Despite this, the potential for global collaboration has not been fully tapped. This study also notes a significant evolution in data analysis methods, transitioning from reliance on single data sources to employing sophisticated multi-source data fusion, from manual feature extraction to leveraging automated deep learning processes, and from simple temporal change detection to comprehensive time series analysis using tools like Google Earth Engine (GEE). This shift encompasses the progression from small-scale case studies to extensive multi-scale system analyses employing advanced spatial statistical models and integrated technologies. Moreover, the thematic emphasis of research has evolved markedly, transitioning from traditional practices like slash-and-burn agriculture and deforestation logging to the dynamic monitoring of specialized tree species such as rubber plantations and mangroves. Throughout this period, there has been a growing focus on the broad environmental impacts of land cover change, encompassing soil degradation, carbon storage, climate change responses, ecosystem services, and biodiversity. This research not only offers a comprehensive understanding of the LULC research landscape in MSEA but also provides critical scientific references that can inform future policy-making and land management strategies. Full article

This study aimed to evaluate the role of trees outside forests on agricultural land (TOF-AL) in preserving the initial aboveground biomass (AGB) of forests within the agricultural landscape of Mongala province in the Democratic Republic of Congo. In 2024, tree inventories were conducted over four months in the forests and agricultural lands of Mongala province to analyse AGB. The effects of artisanal logging and charcoal production activities on the AGB conservation rate were considered. This study indicates that 78.3% of the trees encountered in agricultural lands were large-diameter trees (diameter at breast height (DBH) ≥ 60 cm). In forest areas, large-diameter trees accounted for 55.9% of tree density. The average AGBs are 66.8 Mg ha⁻¹ for TOF-AL and 373.5 Mg ha⁻¹ for forest trees. The AGB of TOF-AL accounts for 17.9% of the AGB of the total forest trees. The AGB conservation rates vary by region, with Lisala having the highest at 22.1%, Bumba the lowest at 11.2%, and Bongandanga at 20.5%. Artisanal logging and charcoal production reduce the AGB conservation rate of TOF-AL. The AGB conservation rate is positively correlated with the distances to major cities. These results prove that conserving trees in agricultural landscapes can reduce the AGB losses associated with slash-and-burn agriculture and contribute to mitigating climate change effects. Full article

Slash-and-burn agriculture (SBA) is critical to maintaining rural peoples’ livelihoods. Yet, it causes environmental degradations that challenge its sustainability. Such degradations are often underestimated, as they are usually assessed at the local (stand) scale, overlooking larger-scale impacts. Here, we drew upon existing SBA and landscape ecology knowledge to assess the multiscale abiotic and biotic effects of SBA. This agroecosystem involves four stages (slashing of vegetation, burning of vegetation, farming, and forest recovery) but the SBA research is biased towards biotic impacts, especially during forest recovery. Despite its importance for key abiotic (e.g., soil fertility) and biotic (e.g., species richness) attribute recovery, this stage is typically too short (<10 years) to compensate for the environmental degradation caused by the previous stages. Successional and landscape ecology theory suggests that such compensatory dynamics can promote SBA sustainability in landscapes dominated by old-growth forests. Yet, when old-growth forest loss exceeds certain boundaries, abiotic and biotic SBA impacts may compromise the conservation value and sustainability of this ancient agroecosystem. We highlight that SBA sustainability should be comprehensively assessed by including landscape-scale variables (e.g., percent old-growth forest cover) that may be key for maintaining biodiversity patterns and processes in landscapes where SBA is practiced. Full article

Fire, a prevalent land management tool in rotational shifting cultivation (RSC), has long been debated for its immediate disruption of surface soil, vegetation, and microbial communities. While low-intensity and short-duration slash-and-burn techniques are considered beneficial for overall soil function, the dual nature of fire’s impact warrants a comprehensive exploration. This review examines both the beneficial and detrimental effects of fire on soil properties within the context of RSC. We highlight that research on soil microbial composition, carbon, and nitrogen dynamics following fire events in RSC is gaining momentum. After fires, soil typically shows decreases in porosity, clay content, aggregation, and cation exchange capacity, while sand content, pH, available phosphorus, and organic nitrogen tend to increase. There remains ongoing debate regarding the effects on bulk density, silt content, electrical conductivity, organic carbon, total nitrogen, and exchangeable ions (K⁺, Ca²⁺, Mg²⁺). Certain bacterial diversity often increases, while fungal communities tend to decline during post-fire recovery, influenced by the soil chemical properties. Soil erosion is a major concern because fire-altered soil structures heighten erosion risks, underscoring the need for sustainable post-fire soil management strategies. Future research directions are proposed, including the use of advanced technologies like remote sensing, UAVs, and soil sensors to monitor fire impacts, as well as socio-economic studies to balance traditional practices with modern sustainability goals. This review aims to inform sustainable land management practices that balance agricultural productivity with ecological health in RSC systems. Full article

A land use analysis of Lac Télé Community Reserve (LTCR) using the Landsat Thematic Mapper (TM), ETM+ images (Enhance Thematic Mapper), and OLI images highlighted significant changes in plant cover between 1986, 1999, and 2019. The rate of forest area increased by 5% from 1986 to 1999 but decreased by 3% from 1999 to 2019 for the entire LTCR, benefitting the growth of savannahs, which respectively increased by 5% between 1986 to 1999 and 12% between 1999 to 2019. The conversion of this forest area to savannah due to the practice of slash and burn agriculture can be justified by the opening of this forest area, but it contributes greatly to the degradation of fish species spawning grounds in the Likouala-aux-Herbes River. According to characterization of the 151 spawning grounds identified, the physical and chemical water parameters, which have been defined as temperature (28.13 °C), hydrogen potential (4.23), and depth (3.34), did not change significantly in the study villages between July and September 2019. The unregistered ichthyological diversity observed during the study in the seven pilot villages, is due to the diversity of the microhabitats noted in the villages of the LTCR, especially in the villages of Botongo, Mossengue, and Bouanela, where the indices of ichthyological diversity were the highest. Full article

Due to slash/burn agricultural activity and frequent forest fires, $P{M}_{2.5}$ has become a significant air pollution problem in Thailand, especially in the north and north east regions. Since its dispersion differs both spatially and temporally, estimating $P{M}_{2.5}$ concentrations discretely by area, for which the inverse Gaussian distribution is suitable, can provide valuable information. Herein, we provide derivations of the simultaneous confidence interval for the ratios of the coefficients of variation of multiple inverse Gaussian distributions using the generalized confidence interval, the Bayesian interval based on the Jeffreys’ rule prior, the fiducial interval, and the method of variance estimates recovery. The efficacies of these methods were compared by considering the coverage probability and average length obtained from simulation results of daily $P{M}_{2.5}$ datasets. The findings indicate that in most instances, the fiducial method with the highest posterior density demonstrated a superior performance. However, in certain scenarios, the Bayesian approach using the Jeffreys’ rule prior for the highest posterior density yielded favorable results. Full article

In the context of climate change, the need to contribute to achieving Sustainable Development Goal (SDG) 2 is no longer in doubt, especially in sub-Saharan Africa. In this study of the landscape within 10 km of the Donomadé model farm, southeastern Togo, researchers sought to assess vegetation health in ecosystems and agrosystems, including their capacity to produce biomass for agroecological practices. Sentinel-2 sensor data from 2015, 2017, 2020, and 2022 were preprocessed and used to calculate the normalized vegetation fire ratio index (NBR), the vegetation fire severity index (dNBR), and CASA-SEBAL models. From these different analyses, it was found that vegetation stress increased across the landscape depending on the year of the time series. The research estimated that 9952.215 ha, 10,397.43 ha, and 9854.90 ha were highly stressed in 2015, 2017, and 2020, respectively. Analysis of the level of interannual severity revealed the existence of highly photosynthetic areas that had experienced stress. These areas, which were likely to have been subjected to agricultural practices, were estimated to be 8704.871 ha (dNBR2017–2015), 8253.17 ha (dNBR2020–2017), and 7513.93 ha (dNBR2022–2020). In 2022, the total available biomass estimated by remote sensing was 3,741,715 ± 119.26 kgC/ha/y. The annual average was 3401.55 ± 119.26 kgC/ha/y. In contrast, the total area of healthy vegetation was estimated to be 4594.43 ha, 4301.30 ha, and 4320.85 ha, in 2015, 2017, and 2022, respectively. The acceptance threshold of the net primary productivity (NPP) of the study area was 96%. The coefficient of skewness (0.81 ± 0.073) indicated a mosaic landscape. Productive and functional ecosystem components were present, but these were highly dispersed. These findings suggest a great opportunity to promote agroecological practices. Mulching may be an excellent technique for enhancing overall ecosystem services as targeted by the SDGs, by means of reconversion of plant biomass consumed by vegetation fires or slash-and-burn agricultural practices. Full article

Despite the technical, socio-economic and environmental challenges, indigenous subsistence agroforestry, generally referred to as slash-and-burn agriculture or bush-fallow farming, is a common practice for local populations in the Democratic Republic of Congo. This study analyzed the proportion of adopters and non-adopters, together with other factors that influence farmers’ choices of adopting agroforestry or that discourage its adoption in the Luki Biosphere Reserve (LBR) area. Data were collected through a survey of 390 households using a structured questionnaire. A logistic regression model, with SPSS Statistics software was fitted to the data against a binary response (1 = adopt; 0 = not adopt). The proportion of adopters of agroforestry practices in the LBR area far exceeds (more than three-fold) that of non-adopters. Six factors exert a positive and significant (p-value = 5%) effect on peasant decisions to adopt agroforestry practices in LBR, including age (51 to 60 years old), marital status, education level, main activity, land tenure and farmers’ membership in a local association. Gender, other age categories, household size, number of years of agroforestry experience, number of assets, distance between residence and fields, and access to credit did not positively influence the adoption of these practices. The results of this study would help engage the indigenous community with different sectors and disseminate agroforestry as a sustainable practice appropriate to the real needs of local populations. Full article

Plants and their associated soil microorganisms interact with each other and form complex relationships. The effects of slash-and-burn agriculture and logging on aboveground plants and belowground microorganisms have been extensively studied, but research on plant–microbial interkingdom ecological networks is lacking. In this study, using old growth forest as a control, we used metagenomic data (ITS and 16S rRNA gene amplified sequences) and plant data to obtain interdomain species association patterns for three different soil disturbance types (slash-and-burn, clear cutting and selective cutting) in a tropical rainforest based on interdomain ecological network (IDEN) analysis. Results showed that the soil bacterial–fungal and plant–microbe ecological networks had different topological properties among the three forest disturbance types compared to old growth forest. More nodes, links, higher modularity and negative proportion were found in the selective cutting stand, indicating higher stability with increasing antagonistic relationships and niche differentiation. However, the area of slash-and-burn forest yield opposite results. Network module analysis indicated that different keystone species were found in the four forest types, suggesting alternative stable states among them. Different plant species had more preferential associations with specific fungal taxa than bacterial taxa at the genus level and plant–microbe associations lagged behind bacterial–fungal associations. Overall, compared with old growth forests, the bacterial–fungal and plant–microbe ecological networks in the slash-and-burn and clear cutting stands were simpler, while the network in the selective cutting stand was more complex. Understanding the relationships between aboveground plants and belowground microorganisms under differing disturbance patterns in natural ecosystems will help in better understanding the surrounding ecosystem functions of ecological networks. Full article

The net arable land area is declining worldwide rapidly due to soil erosion, drought, loss of soil organic carbon, and other forms of degradation. Intense rainfall, cultivation along steep slopes, unscientific land-use changes, shifting cultivation, soil acidity, and nutrient mining in hills and mountains make agriculture unsustainable and less profitable. Hills and mountain ecosystems of the Eastern Himalayan Region (EHR) are further prone to the impact of climate change posing a serious threat to agricultural production and the environment. Increasing soil carbon reserves contributes to multiple ecosystem services, improves soil nutrient and water-holding capacities, and advances climate-resilient agriculture. Thus, carbon sequestration is increasingly becoming an important aspect of farming among researchers in the region. The EHR predominantly practices shifting cultivation that degrades the ecosystem and promotes land degradation and biodiversity loss. Leaching of exchangeable bases is highly favored due to excess rainfall which in turn creates an acidic soil accounting for >84% of the region. Application of lime to raise the soil acidity for the cultivation of crops did not get adequate acceptance among the farming community due to multiple issues such as cost involvement, non-availability in time and place, and transportation issues. The application of biochar as soil amendments is widely known to improve soil’s physical, chemical, and biological properties. Biochar has also emerged as a potential candidate for long-term carbon sequestration due to its inbuilt structure and higher stability. Shift from traditional “slash and burn” culture to “slash and char” might lead to the sequestration of carbon from the atmosphere. Around 0.21 Pg of carbon (12% of the total anthropogenic carbon emissions by land-use change) can be sequestered in the soil if the traditional “slash and burnt” practice is converted to “slash and char”. The objective of this review is to provide detailed information about the role of biochar in altering the soil properties for sustaining agriculture and carbon sequestration, especially for hills and mountain ecosystems. Full article

Spiny thickets or xerophytic thickets (XTs) are a type of shrubby vegetation found in the far south and southwest of Madagascar, the driest parts of the island. This type of vegetation, which is rich in endemic animal and plant species, is endangered. Extensive local goat breeding (Capra hircus, for meat and milk production) based on XT browsing is an important source of household income. The aim of this paper is to analyse the possibility of using improved goat breeding as an alternative to wood charcoal (WC) production and slash-and-burn agriculture (SBA), which are unsustainable activities. The literature on (i) the impacts of SBA, WC production, and goat browsing on the XT ecosystem and (ii) the income provided by these three activities is reviewed to determine the sustainability level of improved goat husbandry. SBA and WC production reduced XT biomass and XT cover area, while goat browsing alone, at a stocking rate of one head per hectare, did not affect XT leaf biomass production and shrub regeneration. Furthermore, batch breeding and flushing techniques provided the highest annual income, mainly from the sale of surplus animal products. This improved goat husbandry may be a sustainable alternative to WC production. However, increasing the current stocking rate is necessary to surpass the combined income of WC production and SBA. An estimation of the XT carrying capacity would offer a basis to assess whether this ecosystem would support a higher stocking rate. Full article

Agricultural expansion has led to a significant loss of habitat and biodiversity in Ghana and throughout West Africa and the tropics generally. Most farmers adopt both organic and inorganic inputs to boost production, with the potential to slow agricultural expansion, but with relatively little consideration of related environmental impacts. In Ghana, where high-input modern farming is rapidly overtaking traditional organic agricultural practices, we examined five stakeholder groups in regard to their perceptions of the environmental, economic, and social costs and benefits of modern, mixed-input, and traditional farming systems. The stakeholder groups included farmers adopting different agricultural practices, as well as governmental and non-governmental natural resource managers. Our findings indicate that the overall perceived costs of modern farming, attributable to large quantities of inorganic inputs, are higher than the overall perceived benefits. Farmers are, however, still motivated to practice modern farming because of perceived higher returns on investment, regardless of environmental impacts, which they tend to discount. Traditional farmers do not use inorganic inputs and instead rely on swidden ‘slash-and-burn’ practices, resulting in declining productivity and soil fertility over time. Since traditional farmers are ultimately forced to encroach into nearby forests to maintain productivity, the perceived environmental sustainability of such farming systems is also limited. Mixed-input farming is not significantly different from modern farming with respect to its perceived environmental and economic traits, because it incorporates agro-chemicals alongside organic practices. Stakeholders’ perceptions and the apparent environmental outcomes of different farming systems suggest that reducing the use of inorganic inputs and promoting the adoption of organic inputs could minimise the negative impacts of agro-chemicals on the forest environment without necessarily compromising productivity. Campaigns to promote low-input or organic agriculture on environmental grounds in West Africa may falter if they fail to recognise farmers’ relatively favourable perceptions of the environmental implications of modern farming practices. Full article

Tropical forest disturbances linked to fire usage cause large amounts of greenhouse gas (GHG) emissions and environmental damages. Supporting precise GHG estimations and counteracting illegal fire usages in the tropics require timely and thematically detailed large-scale information on fire-related forest disturbances. Multi-sensor optical and radar detection and ranging (radar) remote sensing data combined with active fire alerts shows the potential for a more in-depth characterization of fire-related forest disturbances. We utilized dense optical (Landsat-7, Landsat-8 and Sentinel-2) and radar (Sentinel-1) time series to individually map forest disturbances in the province of Riau (Indonesia) for 2018–2019. We combined the sensor-specific optical and radar forest disturbance maps with daily active fire alerts and classified their temporal relationship (predating, coinciding, postdating) into seven so-called archetypes of fire-related forest disturbances. The archetypes reflect sensor-specific sensitives of optical (e.g., changes in tree foliage) and radar (e.g., changes in tree structure) data to detect varying types of forest disturbances, ranging from either a loss of tree foliage and/or structure predating, coinciding or postdating fires. These can be related to different magnitudes of fire-related forest disturbances and burn severities and can be associated with specific land management practices, such as slash-and-burn agriculture and salvage logging. This can support policy development, local and regional forest management and law enforcement to reduce illegal fire usage in the tropics. Results suggest that a delayed or opposing forest disturbance detection in the optical and radar signal is not only caused by environmental influences or different observation densities but, in some cases, such as fire-related forest disturbances, can be related to their different sensitives to detect changes in tree foliage and structure. Multi-sensor-based forest monitoring approaches should, therefore, not simply combine optical and radar time series on a data level, as it bears the risk of introducing artefacts. Full article

For many emerging economies, rapid land use change from forest to farmland is resulting in high levels of land degradation. Farming systems such as maize cultivation under conventional tillage after slash and burn degrade the soil resource through declining soil structural stability. Cultivation enhances mineralisation and hence loss of soil organic matter, which in turn reduces soil structures stability and promotes further carbon losses through soil erosion. Alternative land uses such as fruit tree plantations, or practise change to reduced tillage or conservation agriculture have the potential to counter this spiral of accelerated soil degradation through improving soil structural stability and build-up of soil organic matter. This project assessed how land use influences soil structural stability in Cambodia near Battambang and the North-Western Mountain regions of Vietnam where maize based system are most common. Soil properties measured were: (1) total carbon and nitrogen content analysis, (2) particle and aggregate size distribution using laser refraction, (3) hydraulic conductivity, (4) bulk density and (5) microbial CO₂ respiration. Information on land use history was also collected through farmer surveys. Land use significantly influenced aggregate stability and hydraulic conductivity. This was largely associated with differences in soil organic carbon content. Forest system had the highest, and conventional maize systems had the lowest amount of large aggregates. Fruit tree plantations are relatively new to these regions but they already showed improved soil aggregate sizes though the level of improvement varied and depended on remnant soil. Full article