Spatial dynamics and quantification of deforestation in the central-plateau woodlands of Angola (1990–2009)

Cabral, Ana I. R.; Vasconcelos, Maria J.; Oom, Duarte; Sardinha, R.

doi:10.1016/j.apgeog.2010.09.003

Cited by 56 publications

(37 citation statements)

References 22 publications

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“…This also supports the hypothesis that forests are generally heavily used before they are converted to field areas. This effect has also been observed by Cabral et al (2011) [20], who studied deforestation patterns in central Angola by using a multi-temporal supervised classification. They found that people would rather extract wood from already degraded forests than from intact Miombos, where the time and effort for wood extraction would be disproportionately higher.…”

Section: Resultssupporting

confidence: 66%

“…While the detection of stand-replacing conversion of forest to agriculture has been studied most intensively in general, e.g., [19], and to a lesser degree in Angola [15,20], forest degradation is a subtle modification process [21] that is largely understudied [22,23]. Forest modification is more prevalent than conversion; however, the increased temporal and spatial complexity of measurements has resulted in a far lower number of case studies [24].…”

Section: Introductionmentioning

confidence: 99%

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Using Annual Landsat Time Series for the Detection of Dry Forest Degradation Processes in South-Central Angola

et al. 2017

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Dry tropical forests undergo massive conversion and degradation processes. This also holds true for the extensive Miombo forests that cover large parts of Southern Africa. While the largest proportional area can be found in Angola, the country still struggles with food shortages, insufficient medical and educational supplies, as well as the ongoing reconstruction of infrastructure after 27 years of civil war. Especially in rural areas, the local population is therefore still heavily dependent on the consumption of natural resources, as well as subsistence agriculture. This leads, on one hand, to large areas of Miombo forests being converted for cultivation purposes, but on the other hand, to degradation processes due to the selective use of forest resources. While forest conversion in south-central rural Angola has already been quantitatively described, information about forest degradation is not yet available. This is due to the history of conflicts and the therewith connected research difficulties, as well as the remote location of this area. We apply an annual time series approach using Landsat data in south-central Angola not only to assess the current degradation status of the Miombo forests, but also to derive past developments reaching back to times of armed conflicts. We use the Disturbance Index based on tasseled cap transformation to exclude external influences like inter-annual variation of rainfall. Based on this time series, linear regression is calculated for forest areas unaffected by conversion, but also for the pre-conversion period of those areas that were used for cultivation purposes during the observation time. Metrics derived from linear regression are used to classify the study area according to their dominant modification processes. We compare our results to MODIS latent integral trends and to further products to derive information on underlying drivers. Around 13% of the Miombo forests are affected by degradation processes, especially along streets, in villages, and close to existing agriculture. However, areas in presumably remote and dense forest areas are also affected to a significant extent. A comparison with MODIS derived fire ignition data shows that they are most likely affected by recurring fires and less by selective timber extraction. We confirm that areas that are used for agriculture are more heavily disturbed by selective use beforehand than those that remain unaffected by conversion. The results can be substantiated by the MODIS latent integral trends and we also show that due to extent and location, the assessment of forest conversion is most likely not sufficient to provide good estimates for the loss of natural resources.

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Section: Resultssupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Using Annual Landsat Time Series for the Detection of Dry Forest Degradation Processes in South-Central Angola

et al. 2017

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“…Just under half of the districts experienced overall deforestation (14 of 32 districts), which showed deforestation is not the dominant trend across the districts of Malawi. Similarly, in Angola, not all districts experienced the levels of deforestation that national figures would suggest (Cabral et al 2011). In Tanzania, both continual forest establishment and continual deforestation were found at the village level depending on how traditional the village practices were (Strömquist and Backéus 2009).…”

Section: Change In Forest Areamentioning

confidence: 97%

Deforestation since independence: a quantitative assessment of four decades of land-cover change in Malawi

Bone

Parks

Hudson

et al. 2016

Southern Forests: a Journal of Forest Science

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Land cover has changed rapidly across the tropics over the past century; however, detailed historical information describing the extent and possible drivers of such change is widely lacking. Here, we constructed a history of land-cover change at the district level in Malawi over a 37-year period from 1972 to 2009, the immediate post-colonial phase. Overall, there was a loss of 12 760 km 2 (36%) of original forested area but also 11 161 km 2 of new forest establishment, resulting in a relatively modest overall net loss of 1 599 km 2 (5%). We correlated changes in deforestation and forest establishment with changes in socio-economic variables derived from spatially explicit data from the same time period. Deforestation was positively correlated with (in order of influence) changes in male school attendance, sex ratio, population density, hospital bed numbers, protected areas and dependency rate, but negatively correlated with changes in cattle density; forest establishment broadly showed the inverse relationships with the same variables. Although direct drivers of deforestation are well known for Malawi and much of Africa, the significance of socio-economic variables within this study can help to understand the underlying social pressures behind such drivers. In particular, development, population pressure and demographic factors are important predictors of deforestation rate within our study area.

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“…Increasing human populations are the main threat to tropical dry forests in Africa, inducing changes in land use practices, land cover and fire regimes (Miles et al 2006;Leadley 2010;Cabral et al 2011;Sloan and Sayer 2015). The impact of global change on Africa's dry forests is unclear as predicted climate changes vary at a regional scale while increasing CO 2 and drought can have opposite effects on tree cover (Hély et al 2006;Lucht et al 2006;Thuiller et al 2006;Leadley 2010;.…”

Section: Introductionmentioning

confidence: 99%

Patterns of forest composition and their long term environmental drivers in the tropical dry forest transition zone of southern Africa

et al. 2016

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Background: Tropical dry forests cover less than 13 % of the world's tropical forests and their area and biodiversity are declining. In southern Africa, the major threat is increasing population pressure, while drought caused by climate change is a potential threat in the drier transition zones to shrub land. Monitoring climate change impacts in these transition zones is difficult as there is inadequate information on forest composition to allow disentanglement from other environmental drivers. Methods: This study combined historical and modern forest inventories covering an area of 21,000 km 2 in a transition zone in Namibia and Angola to distinguish late succession tree communities, to understand their dependence on site factors, and to detect trends in the forest composition over the last 40 years.

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Spatial dynamics and quantification of deforestation in the central-plateau woodlands of Angola (1990–2009)

Cited by 56 publications

References 22 publications

Using Annual Landsat Time Series for the Detection of Dry Forest Degradation Processes in South-Central Angola

Using Annual Landsat Time Series for the Detection of Dry Forest Degradation Processes in South-Central Angola

Deforestation since independence: a quantitative assessment of four decades of land-cover change in Malawi

Patterns of forest composition and their long term environmental drivers in the tropical dry forest transition zone of southern Africa

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