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Monitoring 25 years of land cover change dynamics in Africa: A sample based remote sensing approach
Abstract
The study examines the changes in sub-Saharan's natural land cover resources for a 25 year period. We assess these changes in four broad land cover classes – forests, natural non-forest vegetation, agriculture and barren – by using high spatial resolution Earth observing satellites. Two sets of sample images, one ‘historical’ targeted at 1975 and a second ‘recent’ targeted at the year 2000, have been selected through a stratified random sampling technique over the study area, targeting a sampling rate of 1% in each of the strata. The results, presented at eco-region level and aggregated at sub-Saharan level, show a 57% increase in agriculture area at the expense of natural vegetation which has itself decreased by 21% over the period, with nearly 5 million hectares forest and non-forest natural vegetation lost per year. The impacts of these changes on the environment on one site and on the socio-economy on the other site are discussed and possible pressures on human well being are highlighted.
... The expansion of cropland has been a general trend in sub-Saharan Africa. This cropland expansion has been used to meet food demands and cushion low agricultural productivity (Brink & Eva, 2009;Chapoto et al., 2013). The growth of agricultural land at the expense of natural ecosystems raises environmental concerns about habitat loss and deforestation. ...
... Agricultural expansion and utilisation of biomass for wood and charcoal were identified as key drivers of deforestation in Malawi (Ngwira & Watanabe, 2019). In Malawi, about 200,000 and 233,624 hectares of forests were cleared between the 2000-2009and 2009-2015, respectively (Skole et al., 2021. The loss of forests and shrubs in Malawi is a global microcosm. ...
... Agricultural expansion and utilisation of biomass for wood and charcoal were identified as key drivers of deforestation in Malawi (Ngwira & Watanabe, 2019). In Malawi, about 200,000 and 233,624 hectares of forests were cleared between the 2000-2009and 2009-2015, respectively (Skole et al., 2021. The loss of forests and shrubs in Malawi is a global microcosm. ...
Land use and land cover (LULC) changes are inevitable outcomes of socioeconomic changes and greatly affect ecosystem services. Our study addresses the critical gap in the existing literature by providing the first comprehensive national analysis of LULC changes and their impacts on ecosystem service values (ESVs) in Malawi. We assessed changes in ecosystem service values (ESVs) in response to LULC changes using the benefit transfer method in ArcGIS 10.6 software. Our findings revealed a significant increase in grasslands, croplands, and urban areas and a notable decline in forests, shrubs, wetlands, and water bodies. Grassland, cropland, and built-up areas expanded by 52%, 1%, and 23.2%, respectively. In contrast, permanent wetlands, barren land, and water bodies declined by 27.6%, 34.3%, and 1%, respectively. The ESV declined from US85.60 billion in 2022, marking a 5.8% reduction. Provisioning services increased by 0.5% while regulating, supporting, and cultural ecosystem service functions declined by 12.2%, 3.16%, and 3.22%, respectively. The increase in provisioning services was due to the expansion of cropland. However, the loss of regulating, supporting, and cultural services was mainly due to the loss of natural ecosystems. Thus, environmental policy should prioritise the conservation and restoration of natural ecosystems to enhance the ESV of Malawi.
... Africa had lost 16% of its forests and 5% of its woodlands and grasslands over the period of 1975-2000 and at the same time the agricultural areas increased by 57% in sub-Saharan Africa (Brink and Eva, 2009). The forest loss is especially hard on areas with high biodiversity and in the Afromontane areas, where the decrease is estimated to be 3.8% annually according to Eva et al., (2006). ...
... Besides the continental scale studies of land use land cover dynamics (Brink and Eva, 2009), many forest or land-cover-change studies in East Africa indicate intensified land use pressure, evidenced by the loss of forests or bushlands after the 1950s (Lung and Schaab, 2006;Baldyga et al., 2007;Pellikka et al., 2009). A study conducted by Brink and Eva (2009) reported that between 1975 and 2000 significant land use land cover changes have occurred in sub-Saharan ...
... Besides the continental scale studies of land use land cover dynamics (Brink and Eva, 2009), many forest or land-cover-change studies in East Africa indicate intensified land use pressure, evidenced by the loss of forests or bushlands after the 1950s (Lung and Schaab, 2006;Baldyga et al., 2007;Pellikka et al., 2009). A study conducted by Brink and Eva (2009) reported that between 1975 and 2000 significant land use land cover changes have occurred in sub-Saharan ...
In order to identify and sustainably utilize the services rendered by the ecosystem, it is important to understand the process of land cover and land use change and its implications for environmental conditions and ecosystem functioning. Together with GIS, remotely sensed data enhance the capacity to assess the human effects on the environment in quantitative, qualitative and spatial terms. Thus, this study assessed the pattern of LULC dynamics and its impact on soil erosion, soil quality, and organic carbon stocks in Bururi catchment, western highlands of Ethiopia. In this study aerial photographs, Landsat imageries, digital elevation model (DEM), rainfall data, soil data, and socio-economic survey data were analyzed. These data were
obtained from Ethiopian Mapping Agency (EMA), online archives USGS, and National meteorological service agency. The soil data were generated by Laboratory analysis using a standard procedure while the socio-economic data were gathered from 170 sample farm households, key informants, and natural resources management experts of the study area. The Long-term (1957-2018) LULC change analysis was conducted using ERDAS Imagine (2015) software. To verify the accuracy of image classification, Kappa coefficient, producer’s accuracy,
and user’s accuracy were generated. The soil loss of the study catchment was computed by employing a GIS-based Revised Universal Soil Loss Equation (RUSLE) model. To examine the effect of LULC and topographic elevation on soil quality indicators and organic carbon stocks, principal component analysis (PCA) and multi-variate analysis of variance (MANOVA) in the general linear model (GLM) procedure of SPSS (v.24) were used. The socio-economic data collected through questionnaire survey were analyzed in SPSS (v. 24) by employing both descriptive statistics and binomial logistic regression. The qualitative data gathered through
interview, FGD, and field observations were used to substantiate the quantitative analysis of the questionnaire data. The result of LULC change analysis revealed that there have been remarkable changes in the LULC between 1957 and 2018. Forest cover and grassland decreased by 6.7% and 2.8%, respectively. Agricultural, Shrub, and bare/degraded lands had shown increment by 1.3%, 1.9%, and 6.3%, respectively. Due to the effect of the observed LULC change, the mean annual soil loss recorded in 1957 was 41.04 t ha-1 yr-1 whereas in 2018 increased to 48.91 t ha-1 yr -1. On the other hand, LULC and topographic elevation were found to significantly influence the spatial distribution of soil quality indicators and organic carbon stocks. Higher SOC stocks were found under forest cover, shrub land, and grassland compared to agricultural and degraded lands. The result of binomial logistic regression revealed that out of sixteen hypothesized independent variables, twelve were found to have significant influence on farmers’ decision to implement land management practices. In general, the LULC dynamics observed in the area remarkably impacted soil erosion, soil quality indicators, and organic
carbon stocks. Given the severity and magnitude of the problem following LULC dynamics, the study recommends a design of proper land use policy and sustainable management of land resources to reverse the prevailing land degradation in the study area. The designed land management options need to consider the socio-demographic, biophysical, and institutional factors in the study catchment.
... However, the reserve faces threats from deforestation, agricultural expansion, and the development of infrastructure, which have the potential to significantly alter the landscape and disrupt the delicate ecological balance (Nkembi et al., 2019;Nkembi and Maisels, 2020). Satellite remote sensing and geographic information systems (GIS) have become essential tools for quantifying, mapping, and detecting LULCC patterns in Africa and Cameroon (Brink and Eva, 2009;Ordway et al., 2017). Digital change detection techniques, such as post-classification comparison (PCC), have been widely employed to identify and describe the prevalent changes in land cover and land use (Gao and Liu, 2010;Mondal et al., 2016). ...
... LULCC studies have been conducted in various environments, including agriculturally productive, arid, and semi-arid regions (Rembold et al., 2000;Shalaby and Tateishi, 2007;Gao and Liu, 2010). LULCC studies in Africa have been conducted in various environments, including tropical forests, savannas, and urban areas (Brink and Eva, 2009;Teferi et al., 2013;Ordway et al., 2017). However, the impacts of LULCC are particularly acute in developing countries, where rapid urbanization and population growth often lead to the encroachment of valuable natural habitats and agricultural lands (Lambin et al., 2003;Megevand, 2013). ...
Purpose: The purpose of this article is to analyze the spatiotemporal dynamics of land use and land cover (LULC) changes in the Ebo Forest Reserve, a biodiversity hotspot in West Africa, over a 30-year period from 1994 to 2024. Materials and Methods: This study employed high-resolution satellite imagery from the Landsat sensor and a supervised classification approach to delineate LULC classes, including Dense Forest, Secondary Forest/Agricultural Land, and Settlements/Bare Soils. An accuracy assessment was conducted to validate the LULC maps, revealing overall accuracies of 99.08% in 1994, 99.89% in 2009, and 100% in 2024. Findings: The results demonstrated a significant decline in Dense Forest cover from 98.0% in 1994 to 82.0% in 2024, alongside an increase in Secondary Forest/Agricultural Land (from 1.8% to 8.3%) and Settlements/Bare Soils (from 0.2% to 9.7%). These changes reflect the evolving needs of rural communities, driven by population growth, agricultural expansion, and infrastructure development. Climate change was identified as a critical driver affecting ecosystem productivity and resilience. Implications to Theory, Practice and Policy: The findings underscore the need for a balanced approach to managing LULC changes and climate impacts, ensuring sustainable resource management while supporting community development. Policymakers should prioritize frameworks that facilitate sustainable practices to preserve the ecological integrity of the Ebo Forest Reserve.
... In recent years, the rapid expansion of African cities, high population growth, and extensive agricultural development have caused the increasing destruction of sparse vegetation (Gibbs et al., 2010), which is led to a deepening dependence of people on natural resources and posed a great challenge for ecological sustainability (Egoh et al., 2012;Güneralp et al., 2017). It has been reported that between 1975 and 2000, 16% of forests and 5% of open woodlands and shrublands disappeared, while agricultural land expanded by 57% and agricultural production increased by almost 50%, with a clear trend of conversion of natural vegetation to crops (Brink & Eva, 2009). By 2050, food demand in sub-Saharan Africa is projected to triple (Van Ittersum et al., 2016), at which point land degradation and population growth will pose greater threats to agricultural production (Müller et al., 2011;Pironon et al., 2019). ...
... Anthropogenic activities are an important factor influencing wind erosion, mainly through the land cover change by cropland reclamation, grazing, and urban expansion (Blanco-Canqui & Lal, 2008). Africa is one of the most populous continents in the world, and the expansion of agriculture is inextricably associated with population growth (Brink & Eva, 2009). Therefore, in this study, when exploring the spatial drivers of wind erosion, the harvest area and population density were selected as drivers to explore the influence of anthropogenic activities on the spatial distribution of wind erosion. ...
Wind erosion is one of the main causes of land degradation and desertification. Clarifying the spatiotemporal variations of wind erosion and the dominant factors of its spatial characteristics and the temporal trend will contribute to the establishment of appropriate wind erosion control and management practices, which is essential for combating global land degradation and strengthening ecological protection in drylands. Here, we assessed wind erosion in Africa during 2001–2020 based on the Revised Wind Erosion Equation (RWEQ). We also analyzed the influential factor of spatial characteristics and temporal variation based on machine learning and other methods under different aridity. Results revealed that the average annual wind erosion modulus was 16,672 t/km²/a in Africa during 2001–2020, with hyper‐arid areas and arid areas accounting for more than 90% of the total wind erosion modulus. The spatial characteristics of wind erosion were dominated by natural factors but not anthropogenic activities. Except in hyper‐arid areas, wind speed and vegetation coverage together dominated the spatial characteristics. Wind speed was the dominant factor in wind erosion change, while in arid and semi‐arid areas, the capability of vegetation coverage to affect wind erosion change was comparable to wind speed. It can be concluded that, although revegetation does contribute to the reduction of wind erosion in arid and semi‐arid areas, taking into account water resource constraints and land use conflicts, large plantations can be replaced with windbreaks to increase vegetation coverage while reducing near‐surface wind speed, which improves the sustainability of ecological projects aimed at combating land degradation and desertification.
... Besides natural fires, people set fires for various reasons such as to clear ground for agriculture, to achieve higher visibility and to stimulate an offseason re-growth of perennial herbs (Krohmer 2004). During the last decades, the African savannas were subject to high climatic variability and land-use changes (Hickler et al. 2005;Wezel and Lykke 2006;Brink and Eva 2009). Land-use changes account for 70-80% of the biodiversity changes in the African savannas (de Chazal and Rounsevell 2009). ...
... The percentage of land intensively used for agriculture has increased in Africa, and agricultural systems have been intensified due to the growing use of fertilisers and pesticides. Land-use changes are driving the loss of natural habitats, biodiversity and stored carbon and the loss of other ecosystem services (Brink and Eva 2009). The reduction of natural resource capital leads to an increased risk of soil erosion, land degradation and of natural hazards such as floods. ...
This chapter introduces the different agroforestry systems (AFSs) as part of the diversification of agricultural landscapes and gives examples of their use in different related crop production systems in southern Africa. The introduction of trees into agriculture has several benefits and can mitigate the effects of climate change. For example nitrogen-fixing trees and shrubs contribute significantly to nutrient recycling and benefit soil conservation, which is particularly important for smallholder farms. In addition, shelterbelts play an important role in reducing wind speeds, and thus, evapotranspiration, and modifying the microclimatic conditions, which is an important factor for the adaptation of cropping systems to climate change. These integrated AFS landscapes provide important ecosystem services for soil protection, food security and for biodiversity. However, deficiencies in the institutional and policy frameworks that underlie the adoption and stimulus of AFS in the southern African region were identified. Furthermore, the following factors must be considered to optimise AFS: (1) selection of tree species that ensure maximum residual soil fertility beyond 3 years, (2) size of land owned by the farmer, (3) integrated nutrition management, where organic resources are combined with synthetic inorganic fertilisers and (4) tree-crop competition in the root zone for water.
... 60 yr, however, the continent's human population has expanded rapidly 10 , driving widespread land conversion and habitat degradation, and creating areas where cumulative human impacts on threatened raptors are especially acute 9 . Sub-Saharan Africa lost almost 5 million ha of forest and non-forest natural vegetation per annum during 1975-2000 alone 14 and now experiences the most severe rate of land degradation in the world 15 . With its human population projected to double by 2058, demands for grazing, arable land and energy are expected to rise substantially 10,16 . ...
... Since vegetation structure in the vicinity of survey transects was not assessed, we were unable to test whether changes in woody cover had occurred along the routes surveyed. Although widespread changes in shrub encroachment have been reported 14,71 , their effects are likely to have been small in comparison with many of the declines reported here. Moreover, although shrub encroachment would seem less likely to impede the detection of large soaring raptors, these species had shown some of the steepest declines (Supplementary Information: Detectability). ...
The conversion of natural habitats to farmland is a major cause of biodiversity loss and poses the greatest extinction risk to birds worldwide. Tropical raptors are of particular concern, being relatively slow-breeding apex predators and scavengers, whose disappearance can trigger extensive cascading effects. Many of Africa’s raptors are at considerable risk from habitat conversion, prey-base depletion and persecution, driven principally by human population expansion. Here we describe multiregional trends among 42 African raptor species, 88% of which have declined over a ca. 20–40-yr period, with 69% exceeding the International Union for Conservation of Nature criteria classifying species at risk of extinction. Large raptors had experienced significantly steeper declines than smaller species, and this disparity was more pronounced on unprotected land. Declines were greater in West Africa than elsewhere, and more than twice as severe outside of protected areas (PAs) than within. Worryingly, species suffering the steepest declines had become significantly more dependent on PAs, demonstrating the importance of expanding conservation areas to cover 30% of land by 2030—a key target agreed at the UN Convention on Biological Diversity COP15. Our findings also highlight the significance of a recent African-led proposal to strengthen PA management—initiatives considered fundamental to safeguarding global biodiversity, ecosystem functioning and climate resilience.
... However, in many sub-Saharan African countries, step-up efforts by farmers are faced with major challenges despite their perceived importance among all MSFs. Such challenges include limited availability of cultivable land, increasing demand for land for non-agricultural purposes (Brink and Eva, 2009;Lambin and Meyfroidt, 2011), climate change and its impacts on arable land (Lambin et al., 2013), more stringent environmental regulations , and geopolitical factors such as restrictive zoning schemes, weak rural governance, corrupt regimes, and political instability (Chamberlin, Jayne, and Headey, 2014;Lambin et al., 2013). Given the growing importance of MSFs and the role of stepping-up in their growth, it is important to clearly understand the role of existing impediments to stepping-up and identify new challenges. ...
... Several barriers to stepping-up for SHFs have been identified in the literature. Growth in human population is considered to be as a major barrier (Brink and Eva, 2009;Lambin and Meyfroidt, 2011), which increases the demand for land for non-agricultural development purposes and the price of land for farmers. Growing per capita consumption of material goods also increases the demand for land for industrial purposes, also putting upward pressures on land prices (ibid). ...
Land expansion by existing smallholder farmers (SHFs), aka stepping-up, is a major pathway to the rise of medium-scale farmers (MSFs) in Africa. In this paper, we investigate if and how armed conflicts constrain the ability of SHFs to transition to MSFs. We find that increased conflict intensity reduces the likelihood that a SHF will expand to a larger scale, especially for farmers who rely mostly on farm incomes, rather than off-farm incomes, for their livelihoods. These findings uphold other evidence that peace and stability influence private investment, including land-based investments, that are associated with economic transformation.
... The most important conclusion is that when 52% of the arboreal migrants are concentrated in 6.7% of the woody cover (Table 3), it is not total woody cover per se that matters for these birds, but the presence of their preferred woody species. For the same reason, global indications of increase or decline of the woody vegetation, although highly relevant in other respects; Brink & Eva 2009, Hansen et al. 2013 are not helpful in explaining trends in bird populations. Any explanation of these trends must take into account detailed knowledge about the presence and extent of bird-rich and bird-poor woody species within the wintering regions. ...
... Any explanation of these trends must take into account detailed knowledge about the presence and extent of bird-rich and bird-poor woody species within the wintering regions. Furthermore, Brink & Eva (2009) and Hansen et al. (2013) provided the extent of 'forest cover', not of 'woody cover'. In well-wooded regions this may equate the same, but definitely not in the Sahel where low densities of single trees in savannah or farmland cannot be detected with Landsat imagery having a resolution of 30 × 30 m (Figures 6 and 7 in Zwarts et al. 2023a), i.e. the data source used in their studies. ...
The Sahel is thinly covered by trees, but nevertheless forms an important habitat
for millions of tree-dwelling birds. We describe tree availability and tree selection
of 14 insectivorous Afro-Palearctic migrants and 18 Afro-tropical residents (10
insectivores, 3 frugivores and 5 nectarivores) inhabiting the Sahel from the
Atlantic to the Red Sea. Of the 304 woody species identified across the region
during systematic fieldwork in stratified plots, we noted height and canopy
surface of 760,000 individual woody plants. Birds present in trees and shrubs
were recorded separately per individual woody plant. 99.5% of the birds were
concentrated in only 41 woody species. For 20 out of 32 bird species, Winter
Thorn Faidherbia albida was the tree species most often used. Two other important
tree species were Umbrella Thorn Acacia tortilis and Desert Date Balanites
aegyptiaca. Representing only 11% of the total woody canopy cover, these three
species attracted 89% of Western Bonelli’s Warblers Phylloscopus bonelli and
77% of Subalpine Warblers Curruca iberiae + subalpina + cantillans. High selectivity
for particular woody species was typical for migrants and residents, irrespective
of their diet. Bird species feeding in shrubs used a larger variety of
woody species than bird species feeding in tall trees. The highest bird densities
(80–160 birds/ha canopy) were found in three shrubs with a limited distribution
in the southern Sahara and northern Sahel: the berry-bearing Toothbrush Tree
Salvadora persica, the small thorny shrub Sodad Capparis decidua and the
small tree Maerua crassifolia. Other bird-rich woody species were without
exception thorny (Balanites aegyptiaca, various species of acacia and ziziphus).
In contrast, the five woody species most commonly distributed across the region
(Cashew Anacardium occidentale, African Birch Anogeissus leiocarpus, Com -
bretum glutinosum, Guiera senegalensis and Shea Tree Vitellaria paradoxa),
representing 27% of the woody cover in the study sites, were rarely visited by
foraging birds. In this sub-Saharan region, it is not total woody cover per se that
matters to birds, but the presence of specific woody species. This finding has
important implications: remote sensing studies showing global increase or
decline of woody vegetation without identifying individual species have little
value in explaining trends in arboreal bird populations. Local people have a large
impact on the species composition of the woody vegetation in the Sahel, with
positive and negative consequences for migrants wintering in this region.
Faidherbia albida, the most important tree for birds in the sub-Saharan dry belt,
is highly valued by local people and has the distinction of leafing in winter and
being attractive to arthropods. On the other hand, migratory and African bird
species have been negatively affected by the rapidly expanding cashew plantations
since the early 1980s.
... From 1975 to 2000, Africa lost 16% of its forest and 5% of its woodland and grassland; almost 50,000 km 2 of native vegetation vanished annually (Eva et al. 2006). In Sub-Saharan Africa (SSA), agricultural land was increased by 57% at the expense of natural vegetation (Eva et al. 2006;Brink and Eva 2009). ...
This study analyzed Land Use and Land Cover (LULC) change in the Upper Tekeze Basin using Google Earth Engine (GEE) and the Random Forest (RF) classifier. Remote sensing data from Landsat 5 (TM) for 1986, Landsat 7 (ETM+) for 1998 and 2010, and Landsat 8 (OLI) for 2022 were used to classify LULC classes. To triangulate the satellite imagery results, field data from 178 randomly selected households and 15 local elders were used. The study results revealed that from 1986 to 2022, water bodies, forests, cultivated land, settlements, and bare land increased by 100%, 37.84%, 13.93%, and 11.73%, respectively. In contrast, grassland, and shrub and bushland areas decreased by 82.08% and 18.84%, respectively. Moreover, the results show that about 62.92% of the landscape experienced at least one LULC transition, with 18.27% net change and 43.65% swap change. The findings show that most land covers have changed to cultivated land and settlements. The accuracy analysis of the Landsat images showed a satisfactory level, as the changes in LULC align with local perceptions. Local farmers ranked the factors influencing LULC change as follows: agricultural expansion, free grazing, overgrazing, firewood collection, topography, and poor land management, from most to least important. Similarly, local farmers ranked poverty, population growth, rainfall variability, lack of awareness about proper natural resource use, and government intervention, from most to least important, as the root causes of LULC change. Therefore, controlling the causes of LULC change and promoting sustainable resource use are crucial to prevent further LULC change and the loss of scarce natural resources, which are essential for maintaining landscape sustainability.
... These findings reflect the broader trend of land use dynamics in Ivory Coast, particularly in the Oumé Department, where economic, demographic, cultural, and environmental factors underpin social changes that also impact forest cover (Sagne 2009;N'Guessan et al. 2019, N'Guessan et al 2022. Similar trends have been observed in other African regions (Bogaert et al. 2008; Barima et al. 2009;Brink & Eva 2009;Mama et al. 2014;Abdou et al. 2019). ...
Similar to other Ivorian protected forests, the Téné Protected Forest (TPF), located in the Centre-West of Ivory Coast, is experiencing unprecedented anthropogenic pressure, leading to the degradation of its forest cover and changes in land use. This study aims to analyse and predict the spatio-temporal dynamics of land use within the TPF. Land use analysis was conducted using the ENVI 5.1 software over the period 1986–2017, employing Landsat satellite imagery (TM 1986, ETM+ 2000, and OLI 2017). These data were combined with field observations to classify land use in 1986, 2000, and 2017. The classified images were exported to QGIS 2.18, where the MOLUSCE plugin was used to generate a transition matrix. This matrix facilitated modelling via a first-order Markov chain to predict the progression of anthropogenic impacts up to 2029. The results reveal a drastic decline in dense forests, dropping from 20.30% in 1986 to 0% in 2017, replaced by perennial crops, fallow lands, and bare soils. Land use classes exhibited high instability, with an overall stability index below 0.50, indicative of intense anthropogenic pressure. Modelling forecasts a continued decline in the TPF’s forest cover by 2029, with complete disappearance of dense forests and an increase in fallow and bare soils. The findings of this study underscore the urgent need to implement the country’s newly adopted policies for forest preservation, rehabilitation, and expansion in this area, with the aim of safeguarding remaining forest ecosystems and restoring degraded zones.
... 3. Brink and Eva, 2009. Monitoring 25 years of land cover change dynamics in Africa: a sample based remote sensing approach. ...
A search of the recent scientific literature on the impact of human population growth and population density on biodiversity resulted in 131 substantial papers and books published during 2010-2022. A review of this literature found that, in general, population growth and high population density are important drivers of deforestation, defaunation, and biodiversity loss. Increasing human numbers undermine the creation and effectiveness of protected areas and lead to conversion of essential wildlife habitat for agricultural production and other human uses that displace other species. Conversely, local human population decline sometimes provides opportunities for ecological restoration and improves chances of successfully restoring extirpated species. These findings appear to hold at most scales, from local to global, and for most taxa studied. Since large human populations cause biodiversity loss while small populations foster biodiversity protection, future human numbers will play an important role in enabling or preventing a sixth mass extinction of species on the planet Earth.
... Resettlement schemes in Ethiopia have side effects on the environmental, socioeconomic, and cultural settings of the area (Abebe et al., 2019;Brink & Eva, 2009;Deribew, 2019;Porter, 1986). These studies indicate that there was more deforestation, overexploitation of forest resources, expansion of agricultural lands into the frontier of forest cover, and grazing lands in their respective destination areas than natives did. ...
Ethiopia has been experiencing resettlement programs primarily as a response to the tragedy of land degradation. The program, however, resulted in massive deforestation in the resettled sites. This study, therefore, aimed at evaluating the impact of resettlement on the moist evergreen Afromontane forest cover between 2000 and 2018 in the Hawa-Galan district. Landsat TM of 2000, ETM+ of 2010, and OLI of 2018 were used to detect forest cover change. Likewise, an explanatory sequential approach of mixed research design was used. Hence, 118 participants out of the total 2232 indigenous and resettled households were employed to survey the impact of deforestation.The study area lost 55% of its total area over the last two decades, corresponding to average deforestation rates of 2.06, 6.75, and 4.14% for the corresponding periods: respectively. Our findings also revealed the demographic, socioeconomic , and backgrounds of the resettlers were the prominent triggers. Conversion of forests to other uses will have far-reaching impacts on the residual biodiversity and ecosystem services. Therefore, in the light of resettlement, it is high time for the Ethiopian government to revisit its intervention strategies and resettlement policies in the forest priority areas.
... Climate and land-use change are expected to endanger ecosystem services, exacerbate desertification, and land degradation challenges, while changes to land cover are simultaneously driven by increasing populations both in drylands and globally (Smith et al., 2019). In sub-Saharan Africa, agricultural areas increased by 57 % (Brink and Eva, 2009) between 1975and 2000 due to an intensification of food production. There are hopes of alleviating competing land-use pressures with plants that have adapted specifically to arid environments and can generate yields on traditionally non-arable lands (Borland et al., 2009). ...
... In sub-Saharan Africa, the conversion of savannas and forests to croplands has been driven by population growth and food security concerns. Remote sensing analyses have mapped these changes, informing land management strategies (Brink & Eva, 2009). Despite significant progress in understanding LULC changes, several research gaps remain. ...
Land Use Land Cover (LULC) changes have significant environmental and socio-economic implications, necessitating systematic quantification and assessment. This study analyses LULC transitions over two time periods, 1999–2009 and 2009–2019, focusing on key land categories: Forest (FRSD), Agriculture (AGRL), Water Bodies (WATR), Rangeland (RNGE), and Urban Land (URLD). The results indicate substantial land transformations, with agricultural land expansion (637 km², 8.07 annual gain intensity in 2009–2019) occurring at the expense of forest cover (597 km², 1.14 annual gain intensity in 1999–2009). Urban expansion showed a significant increase in intensity, particularly in 2009–2019, with URLD growing by 54.2 km² (9.17 annual gain intensity). Hydrological changes were evident, with water body reduction from 135 km² in 1999–2009 to 154 km² in 2009–2019, significantly impacting ecosystem stability. The transition analysis reveals substantial conversions, including 115 km² of agricultural land shifting to forest cover in 2009–2019, while 10.5 km² of water bodies transitioned to forested areas. These findings underscore the dynamic nature of LULC changes driven by anthropogenic and environmental factors, highlighting the need for sustainable land management strategies.
... Rep.), Chad, Zambia, Angola, and Ethiopia), the contribution of expanding cultivated land area (ρ a = 0.610) to alleviating the food crisis was more than that of cultivated land intensification (ρ i = 0.359). This finding aligns with previous studies emphasizing the importance of cropland expansion under the pressure of growing food demand and low productivity in Sub-Saharan Africa (Brink & Eva, 2009;Chapoto et al., 2013;Grassini et al., 2013). These studies also highlighted cropland expansion as a key strategy for enhancing food security in the region. ...
Africa, despite its rich diversity of food resources, faces severe food crises. Understanding spatial-temporal patterns of cultivated land expansion and intensification levels in Africa is crucial for enhancing food security. This study, based on the GlobeLand30 datasets, revealed changes in African cultivated land from 2000 to 2020, by characterizing the area dynamics, intensification levels, and their coupling patterns. Then, we adopted the partial correlation analysis to explore the relationship between food security and both cultivated land expansion and intensification. Results indicated that the net cultivated land area increased by 6.00 × 10⁷ ha from 2000 to 2020. Over 62% of cultivated land remained stable, and conversions mainly occurred between cultivated land and natural vegetation (forest, grassland, and shrubland). During this period, the intensification level was 35.94% in Africa, and East Africa > North Africa > West Africa > Central Africa > Southern Africa. In addition, nearly half of the countries exhibited high cultivated land intensification levels and area expansion (H-E). We also found that improving intensification levels played pivotal roles in alleviating food insecurity for coastal and middle-income countries, and expanding areas were more important for enhancing food security in inland and low-income countries. Our findings provide a comprehensive overview of cultivated land change in Africa over the past 20 years, serving as a valuable reference for alleviating food insecurity, promoting sustainable economic development, and preserving environmental integrity amidst a growing population.
... From 1975 to 2000, Africa lost 16% of its forest and 5% of its woodland and grassland; almost 50,000 km 2 of native vegetation vanished annually (Eva et al. 2006). In Sub-Saharan Africa (SSA), agricultural land was increased by 57% at the expense of natural vegetation (Eva et al. 2006;Brink and Eva 2009). ...
This study analyzed Land Use and Land Cover (LULC) change in the Upper Tekeze Basin using Google Earth Engine (GEE) and the Random Forest (RF) classifier. Remote sensing data from Landsat 5 (TM) for 1986, Landsat 7 (ETM+) for 1998 and 2010, and Landsat 8 (OLI) for 2022 were used to classify LULC classes. To triangulate the satellite imagery results, field data from 178 randomly selected households and 15 local elders were used. The study results revealed that from 1986 to 2022, water bodies, forests, cultivated land, settlements, and bare land increased by 100%, 37.84%, 13.93%, and 11.73%, respectively. In contrast, grassland, and shrub and bushland areas decreased by 82.08% and 18.84%, respectively. Moreover, the results show that about 62.92% of the landscape experienced at least one LULC transition, with 18.27% net change and 43.65% swap change. The findings show that most land covers have changed to cultivated land and settlements. The accuracy analysis of the Landsat images showed a satisfactory level, as the changes in LULC align with local perceptions. Local farmers ranked the factors influencing LULC change as follows: agricultural expansion, free grazing, overgrazing, firewood collection, topography, and poor land management, from most to least important. Similarly, local farmers ranked poverty, population growth, rainfall variability, lack of awareness about proper natural resource use, and government intervention, from most to least important, as the root causes of LULC change. Therefore, controlling the causes of LULC change and promoting sustainable resource use are crucial to prevent further LULC change and the loss of scarce natural resources, which are essential for maintaining landscape sustainability.
... Брінк і Єва [6], досліджували Африку на південь від Сахари де 16% лісів і 5% відкритих лісів з чагарниками були втрачені між 1975 і 2000 роками, тоді як сільськогосподарські угіддя розширилися на 55%, а виробництво сільськогосподарської продукції зросло майже на 50%. Автори [7], досліджували антропогенні зміни навколишнього середовища та їх вплив на глобальний клімат. ...
The development of erosion processes in many regions of Ukraine remains the most important problem of agriculture. A significant area of eroded land is usually located in areas of developed agriculture, where the vast majority of agricultural products are produced. In modern conditions, anti-erosion organization and arrangement of the territory of arable land of agricultural enterprises should be carried out on the principles of rational use of soil fertility and creation of conditions for conducting adaptive agriculture. In recent years, the issue of global climate warming and its consequences has been increasingly discussed. This aspect of climate warming determined the need for a deeper study of the positions of predicting the manifestation of soil erosion. The development of a system of anti-erosion measures in relation to the conditions of a specific region should be based on a thorough study of soils, relief, the nature of agricultural land and the local climate. Soil erosion in modern conditions is accelerating, which in the future poses a threat to national food security. Land cover and land use change is predicted for the next decade using topography, geology, land use maps and remote sensing data of the studied area. Our study investigated the relationship between agricultural land growth and landscape change. Land use changes assessed among different land cover classes. These changes in the soil cover led to the degradation of the forests of the studied area. The relationship between land use changes and agricultural growth offered a more reliable forecast of soil erosion in Ukraine. This study aims to estimate future changes in climate and land use that may vary in time and space, inherent in a widely used model of soil erosion, and assess the impact of these changes on soil conservation. The model framework is assembled by integrating a dynamic landscape model, a soil erosion model, and generated synthetic rainfall datasets using Monte Carlo simulations. The results suggest that if current trends continue, agricultural areas will occupy approximately 60% of the study area by 2030. Although these land-use changes will certainly increase soil erosion, the new arable land is likely to be mostly in the lowlands, which cover areas with less potential for soil erosion. By 2030, precipitation erosivity is likely to increase during April and November, while there is a slight downward trend in March and May.
... Other studies also reported communities' involvement and awareness and favorable climatic conditions supporting agricultural practices. It is also reported that in Africa, agriculture is increasing by 57% while vegetation cover is decreasing by 21%, with 5 million hectares of forest and non-forest natural vegetation lost annually (Brink and Eva 2009). Other studies pointed out that Zanzibar is endowed with conducive environmental conditions supporting agriculture production, tourism, and related activities (Omar and Cabral 2020;Philemon 2015). ...
Attaining conservation of forests and wildlife resources has been challenging all over the world. The loss of forest cover is among the major threat to biodiversity conservation and is termed a global challenges. Regardless of the intensity of the problem, there is a scarcity of studies examining the conservation threats caused by communities in relation to demographic factors, conservation related challenges facing communities adjacent to the forest, attitudes of the communities towards conservation, and conservation initiatives practiced by the communities adjacent to the Jozani Chakwa Bay National Park (JCBNP). This study used questionnaires, focused group discussions and field observations to bridge this gap. The results indicated different anthropogenic threats reported by communities adjacent to the JCBNP to vary significantly at Cochran’s Q test (4) = 167.822, p < 0.001of which firewood collection and charcoal burning were the leading. The level of education of the respondents found to have a significant (x²(3) = 8.597, p = 0.035) contribution on the use of alternative sources of energy. The occupation of the respondents varied significantly, with most of them (40%) engaging in agriculture. Crop damages reported to be a significant threat at x²(2) = 13.6, p = 0.002 with maize (66%) being highly damaged. Among the problem animals Procolobus kirkii was reported to be the leading. The communities were also found to have a positive attitude towards conservation and were directly involved in conservation related activities. More investment in community education, creating conservation awareness, and the use of alternative crops are recommended for attaining sustainable conservation of forest resources and community development objectives.
... However, although it is found in both closed and cleared forests (Morel & Morel, 1992;Thorup et al., 2019), the species is 715 often found in more open woodland than forests with more complete canopy cover Salewski, Falk, Bairlein, & Leisler, 2002), defending individual territories with both high inter-and intra-annual site fidelity Willemoes et al., 2017;Thorup et al., 2019). There is evidence of prolific land-cover change in sub-Saharan Africa, with a loss of natural forest and grassland habitats through conversion to agriculture (Brink & Eva, 2009). However, our results suggest that this may not necessarily impact negatively on AP migrants, depending on how the cultivated land is managed. ...
Half of all migratory bird species have declined over the past 30 years, with intercontinental migrants declining faster than their short‐distance migratory counterparts. One potential cause of these declines is habitat loss and degradation on tropical wintering grounds, where agricultural conversion of natural habitats and intensification of traditional, low‐intensity agricultural systems are frequently occurring. Although the broad patterns of wintering migrant abundance are well understood along most flyways, how species' habitat associations vary across disturbance gradients in agricultural landscapes remains a key question, with implications for landscape‐level farm management and restoration activities. We used 328 point count locations and associated habitat assessments targeted at a cohort of eight severely declining Afro‐Palaearctic migratory passerines in the Guineo–Congolian transition zone of Western Africa to model the probability of the presence of migrants within grass, shrub, forb and forest‐covered areas. We found support for the widespread use of early successional habitats retained within traditionally managed farmland by migrants. Most species utilize scrubland on fallows within the agricultural mosaic, especially Spotted Flycatcher, Garden Warbler, Melodious Warbler, Whinchat and Common Nightingale. Only Pied Flycatcher relied upon mature forested areas. The avoidance of mature forested habitats by most species suggests that habitat requirements of severely declining migrant birds must be explicitly considered within conservation and restoration schemes, via mechanisms to retain low‐intensity farming, especially short‐term abandoned fallows that regenerate scrubby areas within the agricultural matrix. Any habitat management within the agricultural matrix should be considered in the context of the needs of local communities.
... The increased demand for land resources as a result of the growing population has resulted in both subtle changes, such as an increase in trees outside the forest and a decrease in woody vegetation in savannas, as well as more drastic changes, such as the conversion of land cover from savanna or forest to agriculture (Fig. 7.3). Studies at the local level suggest that the extension of farmland, particularly in semi-arid regions of the continent, is strongly influenced by rural population increase (Brink and Eva 2009). Figure 7.3 shows the two periods of LULC for Africa. ...
Rural populations in sub-Saharan Africa (SSA) face livelihood challenges due to limited opportunities, and increasing dependency on vulnerable landscapes. These challenges are exacerbated by population growth and the consequent ecological footprint, primarily driven by agricultural expansion, leading to significant landscape changes thus affecting tropical forests and semi-arid environments. This book explores the concept of multifunctional landscapes and tree-based ecosystem approaches, highlighting the need for employing sustainable landscape management practices to maximize ecosystem services and ensure equitable benefit distribution.
The book details how the integration of traditional and contemporary agroforestry practices enhances local food security and nutrition, health care provision, and income, identifying a diversity of tree species/taxonomic groups of interest. It emphasizes the role of trees in biodiversity conservation, climate change mitigation and restoration of degraded landscapes while addressing the socio-economic challenges of landscape management. Key tree-based ecosystem management practices such as tree domestication, natural regeneration of trees, assisted or enrichment planting, fire management, sustainable harvesting of non-timber forest products (NTFPs) and agroforestry systems and technologies, are discussed to provide a basis for innovation in integrating trees in multifunctional landscapes in different biophysical contexts across SSA. Ways of overcoming various ecological and socio-economic challenges of landscape management are also discussed, including biocontrol strategies against invasive species and approaches for quality tree germplasms provisioning. The book underscores the need to integrate scientific and indigenous knowledge, and develop adaptive policy and governance to support sustainable landscape management while fostering cultural resilience. It emphasizes the critical role of landscape-scale interventions and large-scale stakeholders’ collaboration through the Community-based natural resource management approach. Notably, the book recognizes the importance of establishing incentives to bolster community engagement, essential to achieving sustainable outcomes.
Future research directions identified include (i) deepening the understanding of ecosystem services provided by trees and the underlying functional traits, (ii) developing innovative practices for sustainable agroforestry practices, (iii) promoting climate-smart agriculture, and (iv) developing more rigorous approaches in assessing both the socio-economic benefits of trees in SSA and the efficacy of policy interventions for sustainable landscape management. By prioritizing holistic and collaborative approaches, stakeholders can ensure the resilience and vitality of SSA’s landscapes, thereby supporting rural livelihoods and biodiversity conservation for future generations.
... The increased demand for land resources as a result of the growing population has resulted in both subtle changes, such as an increase in trees outside the forest and a decrease in woody vegetation in savannas, as well as more drastic changes, such as the conversion of land cover from savanna or forest to agriculture (Fig. 7.3). Studies at the local level suggest that the extension of farmland, particularly in semi-arid regions of the continent, is strongly influenced by rural population increase (Brink and Eva 2009). Figure 7.3 shows the two periods of LULC for Africa. ...
Despite a favourable natural resource base, Africa continues to suffer from high rates of poverty and slow rates of economic growth. Two-thirds of the population in Africa depends on agriculture for their livelihoods. However, a major portion of Africa’s agricultural productivity is static or declining due to soil degradation and climate change. Degradation of forests and woodlands, for instance, has intensified due to rapid growth of human populations that rely on fuelwood for cooking and heating. A few other spatially explicit factors that influence land use and land cover are population density, agricultural expansion, elevation, rainfall, and the distance to roads and settlements. The interactive effects of these drivers that influence land use and land cover change should be considered during decision-making to reduce degradation of land resources used to sustain livelihoods. In this study, Land Use and Land Cover (LULC) detection of Africa over 2017–2022 was analysed using the ESRI Global Land Cover dataset. The results show significant change during the period. Trees, crops, rangeland and built-up areas showed an increasing trend of 0.62%, 0.36%, 0.27 and 0.15%, respectively, while bare ground showed a decreasing trend of 1.26%. For the vast number of countries in Africa whose economies rely on agriculture, net gain changes in LULC associated with crops and rangelands are inevitable in achieving food security. Sustainable land management practices and their upscaling in sub-Saharan Africa are essential for a variety of reasons, but the most basic is to sustain and improve livelihoods while protecting the land’s resources and ecosystem functions. There are some successes in implementing sustainable land management in Africa including agroforestry, community-based natural resource management and the great Greenwall Initiative. Sustainable management of African savanna calls for developing silvicultural systems in the context of understanding the key attributes of African savanna plant species, as this is the basis for addressing the current unsustainable harvesting practices across African savanna landscapes.
... African policymakers associate the primary drivers of deforestation with policy and institutional factors such as weak governance, weak law enforcement, corruption, lack of accountability of forest sector officials, and lack of benefit sharing from forest resources (Hosonuma et al., 2012). Other researchers have attributed the drivers of DFD to subsistence agriculture and fuelwood extraction (Specht et al., 2015;Wehkamp et al., 2015;Boucher et al., 2011;Sanford et al., 2011;Fisher, 2010;Brink & Eva, 2009), urban population growth (DeFries et al., 2010), forced eviction and relocation of local communities, weak property rights, poor engagement and exclusion of local communities in forest management (Duguma et al., 2019). Through focus group discussions, this study assesses the direct and underlying causes of DFD in CREMAs slated for GSLERP implementation in the NSZ. ...
The Ghanaian government has initiated the Ghana Shea Landscape Emission Reductions Project (GSLERP) in northern Ghana to reduce carbon dioxide emissions from deforestation and forest degradation (DFD) and mitigate climate change. This study provides baseline information on the context-specific drivers of DFD and assess the local livelihood capital assets of Community Resource Management Areas (CREMAs) in the Northern Savannah Zone (NSZ) to ensure the effectiveness and sustainability of the project. The study used satellite images to assess the trend of forest cover changes; focus group discussions to identify the main drivers of DFD; and multicriteria decision analysis to determine the best CREMA for pilot demonstration of potential project interventions based on the livelihood capitals. Results showed that forest cover in the NSZ has increased from 1992 to 2020. Bushfire, wood harvesting for fuelwood and charcoal, overgrazing, and illegal logging in that order were considered the leading direct drivers of DFD in the CREMAs, with accompanying underlying causes, including population growth, weak law enforcement, poverty, and limited non-farm livelihood opportunities. The study revealed that social and natural capitals were higher in the CREMAs than human, physical, and financial capitals. We found that Zukpiri CREMA was the best place to conduct a pilot demonstration of interventions to tackle the drivers of DFD, with an uncertainty score of 10%. The findings are valuable for policy-makers and relevant stakeholders in the project landscape to develop policies and programmes for resilient ecosystems and livelihoods in CREMA communities and make better investment decisions for the project’s sustainability.
... Land cover types in Senegal present fluctuations in vegetation patterns as a result of long-term landscape evolution in West Africa [85][86][87][88]. The cumulative effects of climate, environmental, and anthropogenic factors led to a decrease in mangrove colonies, which decline in high-salinity waters [89]. ...
This paper addresses the problem of mapping land cover types in Senegal and recognition of vegetation systems in the Saloum River Delta on the satellite images. Multi-seasonal landscape dynamics were analyzed using Landsat 8-9 OLI/TIRS images from 2015 to 2023. Two image classification methods were compared, and their performance was evaluated in the GRASS GIS software (version 8.4.0, creator: GRASS Development Team, original location: Champaign, Illinois, USA, currently multinational project) by means of unsupervised classification using the k-means clustering algorithm and supervised classification using the Support Vector Machine (SVM) algorithm. The land cover types were identified using machine learning (ML)-based analysis of the spectral reflectance of the multispectral images. The results based on the processed multispectral images indicated a decrease in savannas, an increase in croplands and agricultural lands, a decline in forests, and changes to coastal wetlands, including mangroves with high biodiversity. The practical aim is to describe a novel method of creating land cover maps using RS data for each class and to improve accuracy. We accomplish this by calculating the areas occupied by 10 land cover classes within the target area for six consecutive years. Our results indicate that, in comparing the performance of the algorithms, the SVM classification approach increased the accuracy, with 98% of pixels being stable, which shows qualitative improvements in image classification. This paper contributes to the natural resource management and environmental monitoring of Senegal, West Africa, through advanced cartographic methods applied to remote sensing of Earth observation data.
... LULCC has been observed across the world [6,[15][16][17]. Many studies have also been conducted at the continental [13], regional [18,19], and local levels [6,9,[20][21][22][23][24][25][26][27][28][29][30][31]. Many researchers have studied LULC changes in diferent parts of Ethiopia using GIS and remote-sensing techniques [4,9,[20][21][22][23][24][25][26][27][28][29][30][31]. ...
Land use and land cover change (LULCC) without appropriate management practices has been identified as a major factor contributing to land degradation, with significant impacts on ecosystem services and climate change and hence on human livelihoods. Therefore, up-to-date and accurate LULCC data and maps at different spatial scales are significant for regular monitoring of existing ecosystems, proper planning of natural resource management, and promotion of sustainable regional development. This study investigates the temporal and spatial dynamics of land use land cover (LULC) changes over 31 years (1990–2021) in the upper Tekeze River basin, Ethiopia, utilizing advanced remote sensing techniques such as Google Earth Engine (GEE) and the Random Forest (RF) algorithm. Landsat surface reflectance images from Landsat Thematic Mapper (TM) (1990, 2000, and 2010) and Landsat 8 Operational land imager (OLI) sensors (2021) were used. Besides, auxiliary data were utilized to improve the classification of LULC classes. LULC was classified using the Random Forest (RF) classification algorithm in the Google Earth Engine (GEE). The OpenLand R package was used to map the LULC transition and intensity of changes across the study period. Despite the complexity of the topographic and climatic features of the study area, the RF algorithm achieved high accuracy with 0.83 and 0.75 overall accuracy and Kappa values, respectively. The LULC change results from 1990 to 2021 showed that forest, bushland, shrubland, and bareland decreased by 12.2, 24.8, 1.2, and 15.4%, respectively. Bareland has changed to farmland, settlement, and dry riverbed and stream channels. Expansion of dry stream channels and sandy land surfaces has been observed from 1990 to 2021. Bushland has shown an increment by 17.2% from 1900 to 2010 but decreased by 19.5% from 2010 to 2021. Throughout the study period, water, farmland, dry stream channels and riverbeds, and urban settlements showed positive net gains of 484, 8.7, 82, and 26778.5%, respectively. However, forest, bush, shrub, and bareland experienced 12.17, 24.8, 1.2, and 15.37% losses. The observed changes showed the existing land degradation and the future vulnerability of the basin which would serve as an evidence to mitigate land degradation by avoiding the future conversion of forest, bushland, and shrubland to farmland, on the one hand, and by scaling up sustainable farmland management, and afforestation practices on degraded and vulnerable areas, on the other hand.
... The utilization of Landsat data within the Google Earth Engine platform has become instrumental in mapping extensive areas with a historical context, offering invaluable insights into past land transformations and facilitating predictions of future changes in LULC dynamics (Amini et al., 2022;Devkota et al., 2023;Noi Phan et al., 2020;Abualgasima and Osunmadewa, 2022;Mugari and Masundire, 2022;Brink and Eva, 2009;Simonetti et al., 2015;Babagana-Kyari and Boso, 2020). Through the application of supervised and unsupervised classification approaches, researchers have been able to derive plausible and robust results, enabling the identification of specific land cover classes and transition over time (Pandit et al., 2018a;Belay and Mengistu, 2019;Congalton and Green, 2019;Alshari and Gawali, 2021;Devkota et al., 2023). ...
... In sub-Saharan Africa, habitat loss and fragmentation are increasing due to the rapid expansion of agriculture (Brink and Eva 2008). In West Africa alone, between 1975 and 2013, more than 500,000 km 2 of land was converted into cultivated areas (Herrmann et al. 2020). ...
Chimpanzees (Pan troglodytes) are categorized as Endangered by the International Union for Conservation of Nature, and habitat loss due to conversion of land for agriculture is one of the major threats to wild populations of this species. This challenging scenario can lead to negative human-chimpanzee interactions, including crop feeding. Chimpanzees consume crops across their geographical range, although little is known about this behavior in savanna habitats. Here we provide new evidence of crop feeding by savanna chimpanzees. We conducted our observations at Dindefelo, a community nature reserve in southeastern Senegal. The chimpanzees were observed to feed on mango (Mangifera indica) and also on baobab (Adansonia digitata), a wild species considered a crop by local people when found in and around villages. Although local people use the fruits of these species for food and income, they tolerated crop-feeding events until recently. In 2023, a case of harassment of a crop-feeding chimpanzee in a mango orchard was witnessed, and four days later a chimpanzee corpse was found at the same place. We conclude that habitat conversion into agricultural fields, uncontrolled bush fires and extraction of wild fruits are the important factors influencing crop-feeding events at Dindefelo. Our findings highlight the need to better understand human-chimpanzee interactions in the anthropogenic landscape of Dindefelo to help mitigate negative attitudes and behaviors towards chimpanzees.
... The European turtle dove Streptopelia turtur (hereafter turtle dove) has experienced long-term population declines across its European breeding range (Burns et al., 2020), with a decline of 33% since 1998 leading to the species being classified as "Vulnerable" to extinction (BirdLife International, 2019; Lormée et al., 2020). Various studies in the UK have shown that, in that country, the main cause of these declines is agricultural intensification, which has led to shifts in diet, fewer nesting attempts and lower annual productivity (Browne & Aebischer, 2003a, but agricultural intensification has occurred on both breeding and wintering grounds (Binswanger-Mkhize & Savastano, 2017;Brink & Eva, 2009;Chamberlain et al., 2000;Zwarts et al., 2018). As the only obligate granivorous Afro-Palearctic migrant in Europe, the turtle dove is ecologically unique and is particularly vulnerable, due to a lack of mitigation for depleted natural food resources, with most agri-environment schemes targeting invertebrate food. ...
Agricultural intensification is a major driver in species declines, with changes in land use resulting in widespread alteration of resource availability. An increase in anthropogenic food resources, alongside decreasing natural resources, has resulted in species undergoing dietary changes that can have important ecological consequences, particularly for declining species. Here we use high‐throughput sequencing to analyze the diet of the migrant European turtle dove ( Streptopelia turtur ), a species that has experienced significant population decline throughout its European range. We analyze the diet of this species on both breeding and wintering grounds to gain an understanding of resource use throughout the annual cycle and compare areas of more and less intensive agriculture in western and eastern Europe, respectively. We examine associations with body condition, spatiotemporal variation and the source of food (wild or cultivated). We identified 121 taxonomic units in the diet, with significant variation across sampling seasons, and very little overlap between the breeding and wintering seasons, as well as high levels of cultivated food resources in the diet of turtle doves in both breeding and wintering grounds, with the highest proportion of wild seeds in the diet occurring in birds caught in Hungary, where agricultural intensity was lowest. We detected no association between body condition and the consumption of cultivated food resources. We demonstrate the importance of wild resources in birds on the wintering grounds as they approach migration, where body condition increased as the season progressed, concurrent with an increased consumption of wild seeds. These findings indicate the importance of habitats rich in wild seeds and the need to consider food availability on the wintering grounds, as well as the breeding grounds in turtle dove conservation strategies.
... The Food and Agriculture Organization of the United Nations has released land cover data of Africa. Since 2014, China has successively released GlobeLand30 datasets with coverage of 2000, 2010 and 2020 , which is the first 30m resolution global land cover data product in the world (Liang, L. and Gong, P., 2015;Quinton, W.L., 2011;Begueria, S., 2006;Brink, A. B. and Eva, H. D., 2009;Arsanjani, J.J, 2018). ...
Global land cover (GLC) change reflect the distribution and evolution process of various material types on the earth's surface. It is an important basic data for global natural resources survey and ecological environment research. Although many sets of GLC information service systems have been developed at home and abroad, but the knowledge stock of GLC has not been sufficiently mined, problems such as the knowledge sharing service of spatiotemporal change of GLC have not been solved. This paper reports how to design and construct a GLC spatiotemporal change knowledge service system, which provides users with accurate and in-time knowledge services for GLC spatiotemporal change through knowledge visualization, browsing and querying, knowledge recommendation, knowledge diagnosis, knowledge sharing, process simulation, knowledge graph building and spatiotemporal deduction.
... Many studies conducted by researchers in the context of landscape dynamics in different landscapes of Benin have revealed the same trend (Tchibozo and Domingo 2014;Avakoudjo et al. 2014;Arouna et al. 2016). This regression is associated with the practice of slash-and-burn agriculture, logging for charcoal production, and the rising population in the zone (Oloukoi et al. 2006;Brink and Eva 2009;Barima et al. 2010). Also, the rapid population growth (greater than 3% per year) (Bidou et al. 2019), impacts fallow periods that are not long enough to allow adequate reconstitution of soil fertility and restoration of land productivity (Goma Boumba and Samba-Kimbata 2019). ...
Aims : Land cover change in inselbergs and adjacent areas was studied from 2003 to 2018 in a region facing anthropogenic pressures to assess dynamics and preserve rare endemic species. Study area: Inselbergs and their adjacent areas in the Sudano-Guinean zone of Benin are included in this study. Methods: Land cover classes of inselbergs and adjacent areas were obtained through supervised classification of Sentinel-2 (2018) and Spot 5 (2003) satellite images. A Chi-square test was used to compare protected and unprotected LULC classes of inselbergs, with 10 m spatial resolution. Results: The results showed that forest and woodland decreased respectively from 8.55% to 3.05% and from 17.63% to 4.79% between 2003 and 2018 while tree and shrub savanna, and grassland increased respectively from 6.52% to 9.49% and from 7.60% to 16.69%. Field and fallow increased from 5.57% in 2003 to 26.12% in 2018 and tree plantation from 6.05% to 13.47%. The analysis of spatial comparisons using the chi-square test showed that the presence of inselbergs in a protected area has no significant effect on their land use. Conclusions: Natural vegetation in inselbergs and adjacent areas is being converted into human-made landscapes by farmers. An urgent conservation plan is needed, including awareness campaigns, tree planting, and sustainable forest management.
Taxonomic reference : Akoègninou et al. (2006).
Abbreviations : DEM = Digital Elevation Model; GCP = Ground Control Point; LULC = Land Use/Land Cover; ROI = Region of Interest; SRTM = Satellite imagery data, Shuttle radar topography mission.
... Because of some improval policy in recent years in central Iran, the results of this research are not consistent with many researches. Researches by Li et al. (2018), Brink and Eva (2009) also were mentioned both climatic and terrain factors, and human activities are important effects on vegetation, especially in low-lying areas. One of the most important factors in the increasing change of vegetation is frequent human activities. ...
Air, water, soil, and plant resources have been endangered by human activities in recent years. The aim is to study the trend of changes in these resources using remote sensing data over the last 20 years. The study area of Yazd province (including 24 cities) is in the desert area in the center of Iran. Data were extracted from remote sensing products with web-based software Giovanni NASA and Google Earth Engine platform in the form of time series maps and graphs. The results showed there are two groups, increased and decreased variables. Increased variables were the vegetation density soil temperature, soil organic carbon, black carbon, and evapotranspiration. Decreased variables were wind speed, carbon monoxide, dust, soil moisture, and land surface temperature. Comparing these three categories of climatic, edaphic, and plant factors showed plant and climatic factors had a good trend. Edaphic factors only 50% of them had a good trend. In climatic factors, evapotranspiration had an unfavorable trend, but temperature and wind speed had a good trend. We found good trends; for example, enhanced vegetation index (EVI) had 42%, increasing relative minimum and land surface temperature (LST) had about 46% decreasing relative maximum in the desert region in urban areas. The policy of conservation of plant environmental resources in the desert region was caused by increasing vegetation cover density and decreasing dust, wind speed, and air temperature. Good and bad trends were observed in regions with more nighttime light in cities. This method provides a quick review of many various resources in early warning to governments and decision-makers in the region.
... When considering forest landscapes in the tropics, habitat loss, mainly due to large-scale deforestation, has been significant since the inception of deforestation in the 1970s (Brink & Eva, 2009;Carreiras et al., 2014). Large-scale land use changes are likely to reduce vital resources for forest-dependent animal populations, including bats (Rocha et al., 2016;Webala, Mwaura, et al., 2019). ...
Assessing how bats respond to habitat attributes requires an integrative approach to reliably predict direct community‐level effects. We focused on hipposiderid and pteropodid bats because of their diverse resource use patterns, body size ranges, and dispersal abilities. We combined an array of bat species‐level characteristics with key forest stand characteristics that may covary with habitat use. Twelve stations were sampled in the Lomami and Yangambi landscapes, Democratic Republic of the Congo. We investigated whether species‐level flight ability of bats and forest stand characteristics can affect bat commuting flights and community‐level estimates of both species detection and habitat occupancy. We captured bats for 108 trap‐nights. Three sampling events (early evening, middle of the night, and early morning) were replicated for each survey night. Hipposiderids showed an early evening flight peak, while flight activity of pteropodids was constant throughout the night, but increased around the middle of the night. Species capture probability decreased with higher wing loading in hipposiderids and was negatively correlated with higher wing aspect ratio in pteropodids. Forest occupancy of hipposiderids increased along the gradient towards waterways, while pteropodid occurrence was not directly linked to measured forest stand variables. This suggests a consequence of habitat patterns at larger spatial scales, which would need clarifying through additional data collection. We discuss these findings in terms of resource‐use strategies of clutter‐tolerant and clutter‐intolerant species. We argue that the occurrence of specific bat species and their habitat use patterns can serve as surrogate measures of ecosystem health.
... Also species like Lesser Kestrel, Northern Wheatear and Whinchat Saxicola rubetra are frequently observed in agricultural habitats in the Sahel (Limiñana et al. 2012a, Wilson & Cresswell 2010, Blackburn & Cresswell 2015. The surface area of arable land with millet and sorghum has strongly increased in the Sahel in the second half of the previous century in order to feed the ever-growing human population (Brink & Eva 2009, Zwarts et al. 2009). This might benefit species that make use of agricultural habitats. ...
Palearctic migrants wintering in Africa commonly use several sites throughout the winter, a strategy known as ‘itinerancy’. In this way, migrants track spatiotemporal variation in resources. Despite the importance of this strategy for migratory landbirds, we still lack detailed understanding of how variation in environmental conditions affects site use and the timing of movements between sites. We tracked 125 adult Montagu’s Harriers Circus pygargus from Western European breeding populations between 2005 and 2018 using satellite transmitters and GPS trackers. In total, data on 129 complete wintering seasons were obtained, including 33 individuals that were followed in two or more winters. Montagu’s Harriers were itinerant, using on average 3.3 wintering sites, to which they showed high site fidelity between years. The first sites harriers used after arriving in their wintering range were situated in the northern Sahel and were dominated by natural and sparse vegetation. Subsequent sites, situated further south in the Sahel, were mainly dominated by agricultural and natural habitats. Sites used by harriers had higher habitat diversity compared to random sites. Home range size and activity (time flying per day, daily distance) peaked at the last sites harriers used (i.e. the site from which they commenced spring migration). For individuals tracked in multiple seasons, we showed that home range size did not depend on vegetation greenness. However, the birds covered longer daily distances at the same site in drier years compared to greener (wetter) years. Importantly, the timing of the movements between wintering sites was affected by local environmental conditions, with individuals staying for shorter durations and departing earlier from first sites in drier years and arriving earlier at last sites in greener years. We conclude that within the context of a strategy of itinerancy, Montagu’s Harriers are faithful to the sites they use between years (spatial component), but flexible in the timing of use of these sites (temporal component), which they adjust to annual variation in environmental conditions.
... Bats exhibit a wide range of life-history traits and diverse resource use strategies which may make them valuable biological indicators of terrestrial ecosystem health. Habitat loss, mainly due to largescale deforestation, has been particularly severe in tropical regions (Brink & Eva, 2009;Carreiras et al., 2014). Such changes reduce vital resources for forest-dwelling animals, including bats (Rocha et al., 2016;Webala, Mwaura, et al., 2019). ...
Bats exhibit a variety of life-history traits that can serve as valuable surrogate metrics of terrestrial ecosystem health. Here, we investigate how sonotype activity of hipposiderid bats covaries with habitat structure at finer spatial scales. We recorded passive echolocation calls and measured key habitat attributes in six rainforests in the Lomami and Yangambi landscapes, Democratic Republic of the Congo. Using bat passes as a measure of sonotype activity, we clustered echolocation calls based on call structure similarity to control for within-sonotype variation in activity. Over 432 h of recording, we detected 370 passes matching a hipposiderid sonotype in three subgroups, recovering eight potential species. Open habitats negatively affected sonotype activity in the Hipposideros subgroup, which was associated with higher echolocation frequencies. Indeed, activity peaked in the early evening when mean post-sunset temperature was above the nocturnal average and declined until early morning when mean temperatures dropped below the nightly average. All habitat variables were marginally correlated with the activity of the Doryrhina subgroup, whereas Macronycteris was more active in open habitats. Our findings indicate a probable flexibility of habitat use in lower echolocating bats and point to three possible foraging guilds that modulate hipposiderid bat responses to habitat structure.
In this study, Spatio-temporal variations in Vegetation Health (VH) as a function of Normalized Difference Vegetation Index (NDVI), Normalized Difference Red Edge Index (NDRE) and Canopy Chlorophyll Content Index (CCCI) were examined using measurements from Sentinel-2 images during the period 2018–2022 over the rural, urban, industrial, and highway setups in Sonipat district of Haryana, along with the study of air pollutants and meteorological parameters. This has been further extended to break analysis for the assessment of COVID-19 dependent changes on VH using long-term Sentinel-2 (April 2018–2022) and MODIS (2001–2022) NDVI time-series. Chow-test and Break for Additive Seasonal and Trend was used for this. Result revealed a significant (p = 0.00) difference (through ‘student t-test’) in the NDVI, NDRE and CCCI between the year 2020 and other years taken. The average NDVI values for rural (n = 57), urban (n = 108), industrial (n = 82), and highway (n = 77) setups were 0.22 ± 0.06, 0.23 ± 0.02, 0.23 ± 0.05, 0.21 ± 0.04 in non-COVID-19 year (i.e. 2018, 2019, 2021, and 2022) and 0.40 ± 0.12, 0.52 ± 0.07, 0.50 ± 0.09, 0.51 ± 0.06 for COVID-19 year (i.e. 2020) which shows a total of 28%, 47%, 49%, and 86% increase respectively due to lockdown. Results from break analysis of the NDVI time-series have also shown the break during the COVID-19 period (i.e. March–April, 2020) with variable magnitude in various environmental setups again indicating the effect of lockdown on VH. Furthermore, the concentration of PM2.5, PM10, SO2 and O3 were decreased. The study provides a cost-effective solution for the retrieval of information on VH and its governing factors over a large spatial scale.
The rapid expansion of agricultural and pastoral lands into natural ecosystems accelerates terrestrial carbon loss and intensifies carbon emissions. This study quantifies carbon stock dynamics in Ethiopia’s Abbay Basin from 2000 to 2023, driven by land use and land cover (LULC) changes. The LULC was classified using a random forest classification approach from Landsat 7 (2000) and 8 (2015, 2023) imagery. Biomass carbon density data, encompassing both above- and below-ground carbon, were obtained from the Distributed Active Archive Center (DAAC), while soil organic carbon (SOC) (0–30 cm depth) was derived from World Soil Information System. Carbon stock changes were assessed using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model. The results reveal substantial LULC changes: agricultural land expanded from 38.86% to 42.69%, urban areas increased from 0.37% to 3.11%, while shrublands and grasslands declined. These shifts dramatically reduced total carbon stock, from 32.1 million tons in 2015 to 15.3 million tons in 2023, primarily due to deforestation and agricultural conversion. The findings indicate the urgent need for integrated land management strategies that reconcile economic development with ecosystem conservation to maintain carbon stocks and mitigate climate change.
Cameroon territory is experiencing significant land use and land cover (LULC) changes since its independence in 1960. But the main relevant impacts are recorded since 1990 due to intensification of agricultural activities and urbanization. LULC effects and dynamics vary from one region to another according to the type of vegetation cover and activities. Using remote sensing, GIS and subsidiary data, this paper attempted to model the land use and land cover (LULC) change in the Centre Region of Cameroon that host Yaoundé metropolis. The rapid expansion of the city of Yaoundé drives to the land conversion with farmland intensification and forest depletion accelerating the rate at which land use and land cover (LULC) transformations take place. This study aims at assessing the impacts of both agriculture and urbanization on the LULC change in the Centre Region of Cameroon. A detailed LULC map from MAPBOX high resolution images and three LULC maps were produced from Landsat TM-OLI images (1984-2015). A maximum likelihood classification techniques using ERDAS Imagine, showed forest decline with a total loss of 54% in thirty years. Also, Landsat and MAPBOX images to which we added 1951 aerial photograph and SPOT 6 (2006) were used to analyse urban growth in the city of Yaoundé. The results show a remarkable urban spatial spread of the metropolis between 1951 and 2015, with a peak in 2000. Images processing enabled us to analyse the long term dynamics of LULC change since the 1950s in this Region using ArcGIS & QGIS software’s. Based on this dynamic, a LULC projection map was produced using Markov model on IDRISI Selva, demonstrating the decrease of the dense forest (45% in 2015 to 0.25% in 2050). It was estimated that by 2050, the entire dense forest can be depleted if nothing is done, while only 12.67% of the secondary forest would remain in the Region. Such a projected map is very useful to decision makers for council development and urban planning. This effective forest depletion ties with the hypothesis that urbanization of Yaoundé and its secondary surrounding satellite cities (within a radius of 30-100km) is a veritable driving force of deforestation.
Au Sahel, la dégradation exacerbée des ressources naturelles demeure toujours une contrainte majeure pour la mise en œuvre effective des stratégies de développement durable. Cette étude réalisée à l’échelle du bassin versant du Kori Ouallam (Sud-ouest du Niger), vise à examiner les changements environnementaux survenus de 1972 à 2019 et les forces motrices qui en découlent. L’approche méthodologique préconisée implique l’exploitation des données Landsat soutenues par des campagnes d’échantillonnage et des enquêtes de terrain de type ethnobotanique. Les résultats obtenus montrent que dans le bassin versant du Kori Ouallam, les unités d’occupation des sols ont connu des mutations profondes. Celles-ci se manifestent entre autres par un déclin progressif de la couverture végétale qui passe de 32,47 % à 15,64 % entre 1972 et 1986 à seulement 11,15 % en 2019. Cependant, la proportion des surfaces cultivées a augmenté de manière significative (près de 50 %) oscillant entre 25,18 % et 50,97 % pour la période 1972 à 2019. Les sols nus des plateaux et talus ont connu une évolution sporadique allant de 42,34 % à 56,33 % entre1972 et 1986 puis 37,53 % en 2019. L’enquête ethnobotanique montre que 61 % des espèces ligneuses de la zone ont disparu. Celles-ci sont dominées par des espèces appartenant à la famille des Capparaceae, Malvaceae et Rubiaceae. Les autres espèces ligneuses jugées menacées, conservées et introduites, représentent respectivement 20 %, 9 % et 10 % issues en partie de la famille des Fabaceae. L’analyse combinée des différents résultats atteste que l’hostilité du climat et la pression anthropique accrue exercée sur les ressources naturelles constituent les principales forces motrices à l’origine de ces mutations. Il découle de cette étude qu’au Sud-ouest du Niger, la vulnérabilité des écosystèmes pourrait à long terme moduler une tendance à un déséquilibre écologique avec des conséquences drastiques sur la résilience des communautés. Natural resource degradation remains a major constraint to the effective implementation of sustainable development strategies in the Sahel. The aim of this study is to examine the environmental changes that have occurred from 1972 to 2019 and the driving forces in the Kori Ouallam watershed (southwestern Niger). Methodology is based on the exploitation of Landsat data, supported by ethnobotanical surveys. The results show that land use units have undergone profound changes. These include a gradual decline in vegetation cover, from 32.47% to 15.64% between 1972 and 1986, to just 11.15% in 2019. However, cultivated areas have increased significantly, ranging from 25.18% to 50.97% for 1972 and 2019 respectively. Bare soil on plateaus and slopes has changed sporadically, from 42.34% to 56.33% between 1972 and 1986, then 37.53% in 2019. The results of the ethnobotanical survey show that 61% of the zone's woody species have disappeared. These are dominated by species belonging to the Capparaceae, Malvaceae and Rubiaceae families. Other woody species considered threatened, conserved and introduced, represent 20%, 9% and 10% respectively, partly from the Fabaceae family. The main driving forces behind these environmental changes are climate hostility and increasing anthropization. In southwestern Niger, the vulnerability of ecosystems could lead to a trend towards ecological imbalance, with drastic consequences for community resilience.
Ethiopia is experiencing an unprecedented population increase, making the country increasingly vulnerable to problems stemming from the imbalance between population growth and available resources. This rapid growth, especially in rural areas, has reduced land holdings, leading to landlessness and environmental degradation, which are considered causes of migration and resettlement (Dieci and Viezzoli, 1992). As a result, different Ethiopian regimes have initiated resettlement programs aimed at improving the lives of rural people affected by drought-induced famines. Resettlement can be either voluntary or forced. When people choose to resettle on their initiative, it is referred to as 'spontaneous resettlement.' Conversely, if resettlement is imposed by an external agent in a planned and controlled manner, it is known as 'planned resettlement' (Gebre, 2002). Ethiopia has been implementing resettlement programs primarily in response to displacement caused by environmental factors. Some of these resettlement efforts have succeeded, while others have failed. This study aims to examine the practices, challenges, and opportunities of the rural resettlement program in enhancing the livelihoods of resettled households in the Nono district, West Shoa Zone. Mixed research methods were employed, with primary data collected from 129 household heads selected via simple random sampling from two purposefully chosen villages. Additional information was gathered through focus group discussions, key informant interviews, and personal observations. The data were analyzed using descriptive statistics and a multiple linear regression model with SPSS software. The findings indicate that the resettlement program has helped participants diversify their livelihood strategies beyond agriculture and engage in economic, social, political, and environmental activities. The major challenges faced by resettled households include economic, social, political, and environmental issues. Despite these challenges, there were efforts to improve the economic, political, social, and environmental opportunities for resettled households. The multiple linear regression models revealed that factors such as production methods, market access, farmland size, land productivity, access to credit, access to technologies, and education level significantly and positively influenced the income of rural resettles. Although there is variation in livelihood outcomes among households, most have experienced positive changes in their livelihoods.
In the face of a multiplicity of crises – including land cover change, climate hazards, economic uncertainties, social injustice, adaptation and sustainability concerns, relevant stakeholders have taken stern initiatives to avert these phenomena that continuously grow in magnitude and relevance. We investigate the driving mechanisms of land use cover change, across Africa’s sub-regions using integrated remote sensing techniques and existing literature. Modules for Land Use Change Evaluation (MOLUSCE) and ANN-CA were utilized to simulate land use scenarios (2020–2050) in Africa. Fundamental drift in land use systems was found to be driven by an array of socio-political, economic and biophysical factors. Interestingly, land use and recover change (LURC) patterns were observed in the north and west African regions. A regrowth/greening in forests (+2.67 %) and a decline in deserts/barren areas (-16.62 %), grasslands (-16.58 %) and farmlands/shrubs (-12.88 %) can be observed during the last 40 years. Conversely, massive shifts in built-up (+216.52 %) and areas covered by waterbodies (+84.44 %) can be spotted. Predicted trends for natural vegetation estimate 1.69 % and 2.92 % reduction rates annually for forests and grasslands, respectively, over the next 30 years. The piecemeal of evidence provided shows more lands will be converted into built-environment and cultivated lands. Based on these premises, we propose a ‘4R value strategy’ that unifies actions, addresses resource-related conflicts and the drivers identified, amid sustainability concerns. The study’s standpoints prompt the decisions of governments, the scientific community and interested parties to create alternative futures by tackling prevailing trends which aggravate environmental degradation and poverty.
Protecting biodiversity and keeping the Earth’s temperature stable are both very important jobs performed by tropical forests. In the last few decades, remote sensing has given us new tools and ways to track changes in land cover. To understand what causes changes in forest cover, it is important to look at the things that affect those changes. However, there is not enough research that uses a logistic regression model (LRM) and compares the results with machine learning (ML) techniques to investigate the specific factors that cause forest cover change in remote mountainous areas like Thailand’s Mae Hong Son and Chiang Mai Provinces. Following a comparison of an LRM, a random forest, and an SVM, this study of the causes of changes in forest cover in Mae Hong Son found six important factors: soil series, rock types, slope, the NDVI, the NDWI, and the distances to city areas. Compared to the LRM, both the RF and SVM machine learning algorithms had higher values for the kappa coefficient, sensitivity, specificity, accuracy, positive and negative predictions, and sensitivity, especially the RF. Following what was found in Mae Hong Son, when the important factors were examined in Chiang Mai, the RF came out on top. It is believed that these results can be used in more situations to help make plans for restoring ecosystems and to promote long-lasting methods of managing land use.
Changes in land use and land cover (LULC) are becoming recognized as critical to sustainability research, particularly in the context of changing landscapes. Soil erosion is one of the most important environmental challenges today, particularly in developing countries like Ethiopia. The objective of this study was evaluating the dynamics of soil loss, quantifying sediment yield, and detecting soil erosion hotspot fields in the Boyo watershed. To quantify the soil erosion risks, the Revised Universal Soil Loss Equation (RUSLE) model was used combined with remote sensing (RS) and geographic information system (GIS) technology, with land use/land cover, rainfall, soil, and management approaches as input variables. The sediment yield was estimated using the sediment delivery ratio (SDR) method. In contrast to a loss in forest land (1.7 %), water bodies (3.0 %), wetlands (1.5 %), and grassland (1.7 %), the analysis of LULC change (1991–2020) showed a yearly increase in the area of cultivated land (1.4 %), built-up land (0.8 %), and bare land (3.5 %). In 1991, 2000, and 2020, respectively, the watershed's mean annual soil loss increases by 15.5, 35.9, and 38.3 t/ha/y. Approximately 36 cm of the watershed's economically productive topsoil was lost throughout the study's twenty-nine-year period (1991–2020). According to the degree of erosion, 16 % of the watershed was deemed seriously damaged, while 70 % was deemed slightly degraded. Additionally, it is estimated for the year 2020 that 74,147.25 t/y of sediment (8.52 % of the total annual soil loss of 870,763.12 t) reach the Boyo watershed outlet. SW4 and SW5 were the two sub-watersheds with the highest erosion rates, requiring immediate conservation intervention to restore the ecology of the Boyo watershed.
Different populations of hosts and parasites experience distinct seasonality in environmental factors, depending on local-scale biotic and abiotic factors. This can lead to highly heterogeneous disease outcomes across host ranges. Variable seasonality characterizes urogenital schistosomiasis, a neglected tropical disease caused by parasitic trematodes (Schistosoma haematobium). Their intermediate hosts are aquatic Bulinus snails that are highly adapted to extreme rainfall seasonality, undergoing prolonged dormancy yearly. While Bulinus snails have a remarkable capacity for rebounding following dormancy, we investigated the extent to which parasite survival within snails is diminished. We conducted an investigation of seasonal snail schis- tosome dynamics in 109 ponds of variable ephemerality in Tanzania from August 2021 to July 2022. First, we found that ponds have two synchronized peaks of schistosome infection prevalence and observed cercariae, though of lower magnitude in the fully desiccating than non-desiccating ponds. Second, we evaluated total yearly schistosome prevalence across an ephe- merality gradient, finding ponds with intermediate ephemerality to have the highest infection rates. We also investigated dynamics of non-schisto- some trematodes, which lacked synonymity with schistosome patterns. We found peak schistosome transmission risk at intermediate pond ephemeral- ity, thus the impacts of anticipated increases in landscape desiccation could result in increases or decreases in transmission risk with global change.
In the fields of location theory and spatial optimization, heuristic algorithms have been developed to overcome the NP-hard nature of solutions to their problems, which results in an exponential increase in computation time. These algorithms aim to generate good initial solutions, narrow the solution space, and guide the search process to optimality. Geographically stratified random sampling (GSRS) can be regarded as a method to generate such high-quality initial solutions. This study investigates the application of GSRS to solving the p-median location problem on a continuous surface solution space punctuated with weighted demand points, and its impact on the performance of the popular ALTERN heuristic algorithm. Results demonstrate the effectiveness of GSRS in finding optimal p-median solutions, but only for smaller p values: the ALTERN heuristic with initial solutions generated by local spatial means from GSRS for these smaller p always produces optimal final solutions. In contrast, implementing a random search by executing a large number of random initial solutions often produces non-optimal results. Findings reported in this paper also highlight that sample size and degree of positive spatial autocorrelation (PSA) in the geographic distribution of weights influence how close final solutions are to optimality for larger p. Increasing the sample size leads solutions to be concentrated near their optimal counterparts, as does increasing PSA levels.
Changes in Land use-Land cover (LULC) has directly linked to food security, human health, urbanisation, biodiversity loss, trans-border migration, environmental refuge, water and soil quality, and runoff and sedimentation rates, among other processes and it has been recognized as an important factor in changing the environmental modification worldwide. The continuous
degradation of natural resources are observed through LULC at different corners of the earth. Enriched with natural vegetation the tribal dominated, Golamunda block of Kalahandi district, Odisha is studied because of the noticeable changes in Land use and Land Cover. The present study was aimed at studying the pattern and rate of change in Land use and Land Cover in Golamunda Block of Kalahandi district during 2001-16. The change has been detected while taking Landsat imagery as its input for the study. Spectral based classification approach i.e. supervised classification has been performed for the satellite images of three different periods
i.e. 2001, 2009 and 2016. The results reveal the fact that agricultural land, deciduous forest and water bodies have been decreased, while, barren land, scrub forest and settlement increased from 2001-16. The change detection matrix carves the fact that decrease in agricultural land has been converted to barren and settlement, and the significant portion of the deciduous forest diverted to scrub forest. Thus, there is a need to formulate better planning strategies and law enforcement actions to protect forests and scrubs and control the increasing barren land which causes desertification at national as well as regional level.
Целью работы является изучение взаимосвязи между климатическими показателями и изменениями продуктивности (определяется по NDVI) в локальных геосистемах юго-востока Беларуси. Решаемые задачи: изучение временных трендов климатических показателей и NDVI локальных геосистем в 2000–2020 гг.; оценка статистической значимости связи между климатическими показателями и NDVI в различных геосистемах; выявление геосистем, наиболее чувствительных к быстрым климатическим изменениям. Объектами исследований: лесные ненарушенные, болотные
ненарушенные и лесные нарушенные геосистемы. Для ненарушенных лесных и болотных геосистем установлен статистически значимый положительный тренд NDVI. Корреляция NDVI с летними температурой и осадками отсутствует. NDVI лесных геосистем положительно коррелирует со среднегодовой температурой (коэффициент корреляции Спирмена 0,27, р < 0,05) и годовым количеством осадков (0,55, p < 0,001). В лесных нарушенных геосистемах динамика NDVI обусловлена колебаниями проективного покрытия травяной и древесно-кустарниковой растительности; достоверная корреляция NDVI с климатическими показателями отсутствует.
Investigating the interplay of factors that result in a viral zoonotic outbreak is difficult, though it is increasingly important. As anthropogenic influences shift the delicate balance of ecosystems, new zoonoses emerge in humans. Sub-Saharan Africa is a notable hotspot for zoonotic disease due to abundant competent mammalian reservoir hosts. Furthermore, poverty, corruption, and an overreliance on natural resources play considerable roles in depleting biological resources, exacerbating the population's susceptibility. Unsurprisingly, viral zoonoses have emerged in Africa, including HIV/AIDS, Ebola, Avian influenza, Lassa fever, Zika, and Monkeypox. These diseases are among the principal causes of death in endemic areas. Though typically distinct in their manifestations, viral zoonoses are connected by underlying, definitive factors. This review summarises vital findings on viral zoonoses in Africa using nine notable case studies as a benchmark for future studies. We discuss the importance of ecological recuperation and protection as a central strategy to control zoonotic diseases. Emphasis was made on moderating key drivers of zoonotic diseases to forestall future pandemics. This is in conjunction with attempts to redirect efforts from reactive to pre-emptive through a multidisciplinary "one health" approach.
Measuring the aerial extent of tropical deforestation for other than localized areas requires the use of satellite data. We present evidence to show that an accurate determination of tropical deforestation is very di Å cult to achieve by a ' random sampling' analysis of Landsat or similar high spatial resolution data unless a very high percentage of the area to be studied is sampled. In order to achieve a Landsat-derived deforestation estimate within Ô 20% of the actual deforestation amount 90% of the time, 37 of 40 scenes, 55 of 61 scenes and 37 of 45 scenes were required for Bolivia, Colombia and Peru respectively.
Tucker and Townshend (2000) conclude that 'wall-to-wall coverage is needed to avoid gross errors in estimations of deforestation rates' because tropical deforestation is concentrated along roads and rivers. They specifically question the reliability of the 10% sample of Landsat sensor scenes used in the global remote sensing survey conducted by the Food and Agricultural Organization (FAO) of the United Nations. They base their conclusion on simulations with data from Bolivia, Columbia and Peru, in which the size of a 10% sample is 4 @ n h 6 Landsat sensor scenes. However, their conclusion is not valid when extrapolated to larger sample sizes (e.g. n S 40), such as those employed by the FAO and the European Commission for global and pantropical assessments.
Techniques based on multi-temporal, multi-spectral, satellite-sensor- acquired data have demonstrated potential as a means to detect, identify, map and monitor ecosystem changes, irrespective of their causal agents. This review paper, which summarizes the methods and the results of digital change detection in the optical/infrared domain, has as its primary objective a synthesis of the state of the art today. It approaches,digital change,detection from,three angles. First, the different perspectives from which the variability in ecosystems and the change,events have been dealt with are summarized.,Change,detection between pairs of images,(bi-temporal) as well as between,time profiles of imagery,derived indicators (temporal trajectories), and, where relevant, the appropriate choices for digital imagery acquisition timing and change interval length definition, are discussed. Second, pre-processing routines either to establish a more direct linkage between remote sensing data and biophysical phenomena, or to temporally mosaic imagery and extract time profiles, are reviewed. Third, the actual change,detection,methods,themselves,are categorized,in an analytical framework and critically evaluated. Ultimately, the paper highlights how some of these methodological,aspects are being,fine-tuned as this review,is being written, and we summarize the new developments that can be expected in the near future. The review,highlights the high complementarity,between,different change,detection methods.
Timely and accurate change detection of Earth’s surface features is
extremely important for understanding relationships and interactions between
human and natural phenomena in order to promote better decision making.
Remote sensing data are primary sources extensively used for change detection
in recent decades. Many change detection techniques have been developed. This
paper summarizes and reviews these techniques. Previous literature has shown
that image differencing, principal component analysis and post-classification
comparison are the most common methods used for change detection. In recent
years, spectral mixture analysis, artificial neural networks and integration of
geographical information system and remote sensing data have become
important techniques for change detection applications. Different change
detection algorithms have their own merits and no single approach is optimal
and applicable to all cases. In practice, different algorithms are often compared
to find the best change detection results for a specific application. Research of
change detection techniques is still an active topic and new techniques are
needed to effectively use the increasingly diverse and complex remotely sensed
data available or projected to be soon available from satellite and airborne
sensors. This paper is a comprehensive exploration of all the major change
detection approaches implemented as found in the literature.
1] Recent figures on net forest cover change rates of the world's tropical forest cover are used for the calculation of carbon fluxes in the global budget. By applying our deforestation findings in the humid tropics, complemented by published deforestation figures in the dry tropics, to refereed data on biomass, we produced new estimates of net carbon emissions. These estimates are supported by recent, independent estimations of net carbon emissions globally, over the Brazilian Amazon, and by observations of atmospheric CO 2 emissions over Southeast Asia. Our best estimate for global net emissions from land-use change in the tropics is at 1.1 ± 0.3 Gt C yr À1 . This estimate includes emissions from conversion of forests (representing 71% of budget) and loss of soil carbon after deforestation (20%), emissions from forest degradation (4.4%), emissions from the 1997–1998 Indonesian exceptional fires (8.3%), and sinks from regrowths (À3.3%). (2004), Improved estimates of net carbon emissions from land cover change in the tropics for the 1990s, Global Biogeochem. Cycles, 18, GB2008, doi:10.1029/2003GB002142.
We highlight the complexity of land-use/cover change and propose a framework for a more general understanding of the issue, with emphasis on tropical regions. The review summarizes recent estimates on changes in cropland, agricul-tural intensification, tropical deforestation, pasture expansion, and urbanization and identifies the still unmeasured land-cover changes. Climate-driven land-cover mod-ifications interact with land-use changes. Land-use change is driven by synergetic factor combinations of resource scarcity leading to an increase in the pressure of production on resources, changing opportunities created by markets, outside policy intervention, loss of adaptive capacity, and changes in social organization and atti-tudes. The changes in ecosystem goods and services that result from land-use change feed back on the drivers of land-use change. A restricted set of dominant pathways of land-use change is identified. Land-use change can be understood using the con-cepts of complex adaptive systems and transitions. Integrated, place-based research on land-use/land-cover change requires a combination of the agent-based systems and nar-rative perspectives of understanding. We argue in this paper that a systematic analysis of local-scale land-use change studies, conducted over a range of timescales, helps to uncover general principles that provide an explanation and prediction of new land-use changes.
The carbon balance of the world's terrestrial ecosystems is uncertain. Both top-down (atmospheric) and bottom-up (forest inventory and land-use change) approaches have been used to calculate the sign and magnitude of a net terrestrial flux. Different methods often include different processes, however, and comparisons can be misleading. Differences are not necessarily the result of uncertainties or errors, but often result from incomplete accounting inherent in some of the methods. Recent estimates are reviewed here. Overall, a northern mid-latitude carbon sink of approximately 2 Pg C yr−1 appears robust, although the mechanisms responsible are uncertain. Several lines of evidence point to environmentally enhanced rates of carbon accumulation. Other lines suggest that recovery from past disturbances is largely responsible for the sink. The tropics appear to be a small net source of carbon or nearly neutral, and the same uncertainties of mechanism exist. In addition, studies in the tropics do not permit an unequivocal choice between two alternatives: large emissions of carbon from deforestation offset by large sinks in undisturbed forests, or moderate emissions from land-use change with essentially no change in the carbon balance in undisturbed forests. Resolution of these uncertainties is most likely to result from spatially detailed historical reconstructions of land-use change and disturbance in selected northern mid-latitude regions where such data are available, and from systematic monitoring of changes in the area of tropical forests with satellite data of high spatial resolution collected over the last decades and into the future.
Statistical sampling offers a cost-effective, practical alternative to complete-coverage mapping for the objective of estimating gross change in land cover over large areas. Because land cover change is typically rare, the sampling strategy must take advantage of design and analysis tools that enhance precision. Using two populations of land cover change in the eastern United States, we demonstrate that the choice of sampling unit size and use of a survey sampling regression estimator can significantly improve precision with only a minor increase in cost.
Protected areas such as nature reserves have been found to be effective in preventing habitat destruction and protecting ecosystems within their borders. Recent studies however found extensive loss of tropical forest habitat around protected areas, vastly contributing to increase the levels of ecological isolation. Using high-resolution satellite data we investigated the isolation trend occurring in the W-Arly-Pendjari (WAP) ecological complex in West Africa. A land-cover change analysis was performed for the period 1984–2002: savanna vegetation extension and loss were derived within the complex and in a 30 km peripheral buffer. Sample regions in the buffer were also analysed using selected spatial indicators to quantify temporal trends in habitat fragmentation. Implications for change in relative capacity to conserve biodiversity were discussed through the calculation of the species richness capacity (SRC). More than 14.5% of savanna habitat was lost in the WAP peripheral areas, while 0.3% was converted inside the complex. The degree of fragmentation of remnant savanna habitat has also drastically increased. Despite the effectiveness of the park conservation programme, we found through the SRC approach that the WAP complex is decreasing its potential capacity to conserve species richness. This process is mainly due to the rapid and extended agricultural expansion taking place around the complex. A better understanding of the ecological dynamics occurring in the peripheral regions of reserves and the consideration of development needs are key variables to achieve conservation goals in protected areas.
The development of appropriate validation techniques is critical to assess uncertainties associated with satellite-data-based products, to identify needed product improvements and to allow products to be used appropriately. At regional to global scales, there are several outstanding issues in the development of robust validation methodologies, including the need to increase the quality and economy of product validation by developing and promoting international validation standards and protocols. This paper describes a protocol developed to validate a regional southern Africa burned- area product derived from Moderate Resolution Imaging Spectroradiometer (MODIS) 500 m time series data. The protocol is based upon interpretations by members of the Southern Africa Fire Network (SAFNet) of multitemporal Landsat Enhanced Thematic Mapper plus (ETM +) data to derive maps of the location and approximate date of burning. The validation data are derived using Landsat ETM + scenes distributed to encompass representative regional variation in the conditions for which the MODIS burned-area product was generated and to capture the more important factors that influence product performance. The protocol was developed by consensus to ensure inter- comparison of the independent data derived by the different SAFNet members and to allow these data to be scaled up to provide regional validation of the MODIS burned-area product. Biomass burning in southern Africa, the ETM + sampling rationale, the interpretation and mapping approach, SAFNet member fire activities, and illustrative 2001 results and difficulties encountered with the protocol are described.
The relationship between changes observed in multi-temporal remotely sensed data and disturbance processes are increasingly being studied in support of various land process modelling and management decision applications. The possibility of mapping both the location and degree of change and retrieving information concerning the disturbance process are primary goals. This paper studies changes in reflective wavelength data caused by the action of fire. We consider the heterogeneity of fire effects in terms of the fraction of the observation that burned (f) and the combustion completeness (cc). A spectral mixture model and field and satellite observations of prescribed fires are used to examine the relationship between change in reflectance, and cc and f. The prescribed fires were lit in different South African savannah types during the SAFARI 2000 dry season campaign. Implications for the development of methods to retrieve cc and f, for the development of methods to map the spatial extent of fire-affected areas with known detection capabilities are discussed.
A recently completed research program (TREES) employing the global imaging capabilities of Earth-observing satellites provides
updated information on the status of the world's humid tropical forest cover. Between 1990 and 1997, 5.8 ± 1.4 million hectares
of humid tropical forest were lost each year, with a further 2.3 ± 0.7 million hectares of forest visibly degraded. These
figures indicate that the global net rate of change in forest cover for the humid tropics is 23% lower than the generally
accepted rate. This result affects the calculation of carbon fluxes in the global budget and means that the terrestrial sink
is smaller than previously inferred.
Land use has generally been considered a local environmental issue, but it is becoming a force of global importance. Worldwide
changes to forests, farmlands, waterways, and air are being driven by the need to provide food, fiber, water, and shelter
to more than six billion people. Global croplands, pastures, plantations, and urban areas have expanded in recent decades,
accompanied by large increases in energy, water, and fertilizer consumption, along with considerable losses of biodiversity.
Such changes in land use have enabled humans to appropriate an increasing share of the planet's resources, but they also potentially
undermine the capacity of ecosystems to sustain food production, maintain freshwater and forest resources, regulate climate
and air quality, and ameliorate infectious diseases. We face the challenge of managing trade-offs between immediate human
needs and maintaining the capacity of the biosphere to provide goods and services in the long term.
Many foreign countries are as dependent on imports of food as the United States is on imports of oil. As the world's largest
exporter of food, the United States needs reliable information on fluctuating foreign crop production. But available information
is often inadequate and at best untimely. It is gathered by the foreign governments' often outmoded systems and its release
may be delayed out of economic self-interest. Recently three U.S. government agencies put together a crop inventory system
using satellite remote sensing and worldwide weather reporting and tested it in the Large Area Crop Inventory Experiment (LACIE).
A 1977 real-time forecast of U.S.S.R. wheat production indicates that the approach works and may be expandable to other areas
and other crops.
Forest cover is an important input variable for assessing changes to carbon stocks, climate and hydrological systems, biodiversity richness, and other sustainability science disciplines. Despite incremental improvements in our ability to quantify rates of forest clearing, there is still no definitive understanding on global trends. Without timely and accurate forest monitoring methods, policy responses will be uninformed concerning the most basic facts of forest cover change. Results of a feasible and cost-effective monitoring strategy are presented that enable timely, precise, and internally consistent estimates of forest clearing within the humid tropics. A probability-based sampling approach that synergistically employs low and high spatial resolution satellite datasets was used to quantify humid tropical forest clearing from 2000 to 2005. Forest clearing is estimated to be 1.39% (SE 0.084%) of the total biome area. This translates to an estimated forest area cleared of 27.2 million hectares (SE 2.28 million hectares), and represents a 2.36% reduction in area of humid tropical forest. Fifty-five percent of total biome clearing occurs within only 6% of the biome area, emphasizing the presence of forest clearing “hotspots.” Forest loss in Brazil accounts for 47.8% of total biome clearing, nearly four times that of the next highest country, Indonesia, which accounts for 12.8%. Over three-fifths of clearing occurs in Latin America and over one-third in Asia. Africa contributes 5.4% to the estimated loss of humid tropical forest cover, reflecting the absence of current agro-industrial scale clearing in humid tropical Africa.
• deforestation
• humid tropics
• remote sensing
• change detection
• monitoring
This work presents a design-based validation and calibration scheme for the Global Burned Area 2000 (GBA2000) products. The objective of such a scheme is to assess the margins of uncertainty associated with the burned area products and to estimate calibration coefficients needed to convert burned pixel counts into areal estimates. As the validation of GBA2000 was performed long after 2000, and given the fact that burned areas are a predominantly nonpermanent land cover change, the reference data are obtained from a set of Landsat-7 Enhanced Thematic Mapper Plus high-resolution remotely sensed data. A stratified sampling scheme is presented, specifically designed for the retrospective validation of burned area data; the scheme is based on combining information from two low-resolution burned area products (GBA2000 itself and Globscar). The resulting stratification has been applied to the whole global GBA2000 dataset, and preliminary validation results are reported for Africa. The conclusions highlight the limits of a retrospective validation exercise, and summarize some of the open issues in the validation of global burned area maps
The Joint Research Centre of the European Commission (JRC), in partnership with 30 institutions, has produced a global land cover map for the year 2000, the GLC 2000 map. The validation of the GLC2000 product has now been completed. The accuracy assessment relied on two methods: a confidence-building method (quality control based on a comparison with ancillary data) and a quantitative accuracy assessment based on a stratified random sampling of reference data. The sample site stratification used an underlying grid of Landsat data and was based on the proportion of priority land cover classes and on the landscape complexity. A total of 1265 sample sites have been interpreted. The first results indicate an overall accuracy of 68.6%. The GLC2000 validation exercise has provided important experiences. The design-based inference conforms to the CEOS Cal-Val recommendations and has proven to be successful. Both the GLC2000 legend development and reference data interpretations used the FAO Land Cover Classification System (LCCS). Problems in the validation process were identified for areas with heterogeneous land cover. This issue appears in both in the GLC2000 (neighborhood pixel variations) and in the reference data (cartographic and thematic mixed units). Another interesting outcome of the GLC2000 validation is the accuracy reporting. Error statistics are provided from both the producer and user perspective and incorporates measures of thematic similarity between land cover classes derived from LCCS
We highlight the complexity of land-use/cover change and propose a framework for a more general understanding of the issue, with emphasis on tropical regions. The review summarizes recent estimates on changes in cropland, agricultural intensification, tropical deforestation, pasture expansion, and urbanization and identifies the still unmeasured land-cover changes. Climate-driven land-cover modifications interact with land-use changes. Land-use change is driven by synergetic factor combinations of resource scarcity leading to an increase in the pressure of production on resources, changing opportunities created by markets, outside policy intervention, loss of adaptive capacity, and changes in social organization and attitudes. The changes in ecosystem goods and services that result from land-use change feed back on the drivers of land-use change. A restricted set of dominant pathways of land-use change is identified. Land-use change can be understood using the concepts of complex adaptive systems and transitions. Integrated, place-based research on land-use/land-cover change requires a combination of the agent-based systems and narrative perspectives of understanding. We argue in this paper that a systematic analysis of local-scale land-use change studies, conducted over a range of timescales, helps to uncover general principles that provide an explanation and prediction of new land-use changes.
Les pays africains en voie de développement n'ont pas les moyens financiers ni les capacités technologiques nécessaires pour produire des cartes du couvert fiables et les bases de données géographiques numérisées correspondantes. Pourtant, la disponibilité d'information fiable, livrée dans des délais raisonnables et géographiquement référencée sur l'état actuel du couvert et de la dégradation des terres est une condition primordiale pour la gestion et le développement durable des ressources agricoles, forestières et hydriques. De plus, une telle information est essentielle pour la mise en place de mesures efficaces visant la limitation des dommages causés par les désastres naturels tels que les sécheresses et les inondations en milieu agricole.
Sample surveys data, and Landsat Multispectral Scanner System (uss) and Landsat Thematic Mapper (rv) image data were used to establish forest area estimates within a test site area in the state of Rio Grande do Sul, southern Brazil. Two methods were applied: direct expansion and regression esti-mator methods. For the former, on area frame sampling scheme was used and, for the latter, estimates were corrected by means of classification results. Reference data werc com-piled for two periods through aerid photography interpreta-tion (an) and direct feld observations. The direct expansion method produced rapid and independent area estimates while results from the regression estimator method showed narrower confi dence intewals, indicating higher accurocy. Mean relative efficiency figures for forest classes were 3.63 using the MSS dato set and 7.73 using the ru data set. Find-ings of this study demonstrated the potential and advantages of using Landsat image data for forest area estimation.
A major component of the Joint Research Centre's TREES-II project is the assessment of deforestation rates in moist tropical regions for the period 1992 to 1997 using a statistical sample of fine spatial resolution satellite image pairs. It is widely recognized that spatial stratification can reduce the variance of estimates in spatial sampling designs. However, at the pan-tropical scale little reliable spatial information is available to stratify on the basis of deforestation rates. This paper describes a novel sampling scheme for assessing tropical deforestation rates. Stratification is performed using percentages of forest area (derived from National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) data) and areas of known deforestation activity (elucidated from expert consultation) estimated for each sampling unit. Sample site selection is performed by using a sample frame based on a tessellation of hexagons on a sphere. This approach allows for a sensor-independent sample from which unbiased estimators and error variance may be computed. The scheme is currently in the implementation phase for the tropical belt, but can be extended to the global scale.
Timely and accurate change detection of Earth's surface features is extremely important for understanding relationships and interactions between human and natural phenomena in order to promote better decision making. Remote sensing data are primary sources extensively used for change detection in recent decades. Many change detection techniques have been developed. This paper summarizes and reviews these techniques. Previous literature has shown that image differencing, principal component analysis and post-classification comparison are the most common methods used for change detection. In recent years, spectral mixture analysis, artificial neural networks and integration of geographical information system and remote sensing data have become important techniques for change detection applications. Different change detection algorithms have their own merits and no single approach is optimal and applicable to all cases. In practice, different algorithms are often compared to find the best change detection results for a specific application. Research of change detection techniques is still an active topic and new techniques are needed to effectively use the increasingly diverse and complex remotely sensed data available or projected to be soon available from satellite and airborne sensors. This paper is a comprehensive exploration of all the major change detection approaches implemented as found in the literature.
Historical background, fundamental concepts, statistical considerations and a case study emphasize the need for absolute precision in applying remotely sensed data. This book is a complete guide to assessing the accuracy of maps generated from remotely sensed data.
This article gives an overview of different ways to use satellite images for land cover area estimation. Approaches are grouped into three categories. (1) Estimates coming essentially from remote sensing. Ground data, are used as an auxiliary tool, mainly as training data for image classification, or sub-pixel analysis. Area estimates from pixel counting are sometimes used without a solid statistical justification. (2) Methods, such as regression, calibration and small area estimators, combining exhaustive but inaccurate information (from satellite images) with accurate information on a sample (most often ground surveys). (3) Satellite images can support area frame surveys in several ways: to define sampling units, for stratification; as graphic documents for the ground survey, or for quality control.Cost-efficiency is discussed. Operational use of remote sensing is easier now with cheaper Landsat Thematic Mapper images and computing, but many administrations are reluctant to integrate remote sensing in the production of area statistics.
Question: Can recent satellite imagery of coarse spatial resolution support forest cover assessment and mapping at the regional level?
Location: Continental southeast Asia.
Methods: Forest cover mapping was based on digital classification of SPOT4-VEGETATION satellite images of 1 km spatial resolution from the dry seasons 1998/1999 and 1999/2000. Following a geographical stratification, the spectral clusters were visually assigned to land cover classes. The forest classes were validated by an independent set of maps, derived from interpretation of satellite imagery of high spatial resolution (Landsat TM, 30 m). Forest area estimates from the regional forest cover map were compared to the forest figures of the FAO database.
Results: The regional forest cover map displays 12 forest and land cover classes. The mapping of the region's deciduous and fragmented forest cover remained challenging. A high correlation was found between forest area estimates obtained from this map and from the Landsat TM derived maps. The regional and sub-regional forest area estimates were close to those reported by FAO.
Conclusion: SPOT4-VEGETATION satellite imagery can be used for mapping consistently and uniformly the extent and distribution of the broad forest cover types at the regional scale. The new map can be considered as an update and improvement on existing regional forest cover maps.
A digital land cover map of South America has been produced using remotely sensed satellite data acquired between 1995 and the year 2000. The mapping scale is defined by the 1 km spatial resolution of the map grid-cell. In order to realize the product, different sources of satellite data were used, each source providing either a particular parameter of land cover characteristic required by the legend, or mapping a particular land cover class. The map legend is designed both to fit requirements for regional climate modelling and for studies on land cover change. The legend is also compatible with a wider, global, land cover mapping exercise, which seeks to characterize the world's land surface for the year 2000. As a first step, the humid forest domain has been validated using a sample of high-resolution satellite images. The map demonstrates both the major incursions of agriculture into the remaining forest domains and the extensive areas of agriculture, which now dominate South America's grasslands.
Aim In the framework of the Global Land Cover 2000 (GLC 2000), a land‐cover map of Africa has been produced at a spatial resolution of 1 km using data from four sensors on‐board four different Earth observing satellites.
Location The map documents the location and distribution of major vegetation types and non‐vegetated land surface formations for the entire African continent plus Madagascar and the other surrounding islands.
Methods The bulk of these data were acquired on a daily basis throughout the year 2000 by the VEGETATION sensor on‐board the SPOT‐4 satellite. The map of vegetation cover has been produced based upon the spectral response and the temporal profile of the vegetation cover. Digital image processing and geographical information systems techniques were employed, together with local knowledge, high resolution imagery and expert consultation, to compile a cartographic map product. Radar data and thermal sensors were also used for specific land‐cover classes.
Results A total of 27 land cover categories are documented, which has more thematic classes than previously published land cover maps of Africa contain. Systematic comparison with existing land cover data and 30‐m resolution imagery from Landsat are presented, and the map is also compared with other pan‐continental land cover maps. The map and digital data base are freely available for non‐commercial uses from http://www.gvm.jrc.it/tem/africa/products.htm
Main conclusions The map improves our state of knowledge of the land‐cover of Africa and presents the most spatially detailed view yet published at this scale. This first version of the map should provide an important input for regional stratification and planning purposes for natural resources, biodiversity and climate studies.
Forest monitoring requires more automated systems to analyse the large amount of remote sensing data. A new method of change detection is proposed for identifying forest land cover change using high spatial resolution satellite images. Combining the advantages of image segmentation, image differencing and stochastic analysis of the multispectral signal, this OB-Reflectance method is object-based and statistically driven. From a multidate image, a single segmentation using region-merging technique delineates multidate objects characterised by their reflectance differences statistics. Objects considered as outliers from multitemporal point of view are successfully discriminated thanks to a statistical procedure, i.e., the iterative trimming. Based on a chi-square test of hypothesis, abnormal values of reflectance differences statistics are identified and the corresponding objects are labelled as change. The object-based method performances were assessed using two sources of reference data, including one independent forest inventory, and were compared to a pixel-based method using the RGB-NDVI technique. High detection accuracy (> 90%) and overall Kappa (> 0.80) were achieved by OB-Reflectance method in temperate forests using three SPOT-HRV images covering a 10-year period.
Incl. bibliographical references, index
A textbook prepared primarily for use in introductory courses in remote sensing is presented. Topics covered include concepts and foundations of remote sensing; elements of photographic systems; introduction to airphoto interpretation; airphoto interpretation for terrain evaluation; photogrammetry; radiometric characteristics of aerial photographs; aerial thermography; multispectral scanning and spectral pattern recognition; microwave sensing; and remote sensing from space.
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