Modalités de la déforestation dans le sud-ouest de l'État du Campeche, Mexique

2001 ◽  
Vol 31 (7) ◽  
pp. 1280-1288 ◽  
Author(s):  
J F Mas ◽  
H Puig
Keyword(s):  
Risk Assessment ◽  
Land Tenure ◽  
Government Policy ◽  
Human Population ◽  
Satellite Images ◽  
Forest Cover ◽  
Human Settlements ◽  
Forest Patches ◽  
Forest Clearing ◽  
Deforestation Rates

The analysis of satellite images shows an important reduction of forest cover in the Lagoon of Términos region in the State of Campeche (southeastern Mexico) over the last decades. Deforestation rates reached 2.2 and 5.3%, respectively, on a yearly basis during 1974–1986 and 1986–1991. The deforestation process was modelled using a geographic information system. The model allows to determine how elements such as roads or human settlements proximity, land tenure, shape of the forest patches, slope, soil type, and human population attributes have an impact on the deforestation process. Deforestation was more severe in opened, nonflooded areas, with fertile soil, near roads and human settlements. Human population attributes showed little influence on deforestation rates, probably because pasture lands encroachment was recognized as the main cause of forest clearing. However, the model does not highlight the root causes of this phenomena, such as government policy on settlement and subsidies for cattle ranching. Despite this limitation, it allows to generate deforestation risk assessment maps that correctly identify the forest areas most susceptible to deforestation.

scholarly journals Understanding 34 Years of Forest Cover Dynamics across the Paraguayan Chaco: Characterizing Annual Changes and Forest Fragmentation Levels between 1987 and 2020

Forests ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 25
Author(s):  
Emmanuel Da Da Ponte ◽  
Monserrat García-Calabrese ◽  
Jennifer Kriese ◽  
Nestor Cabral ◽  
Lidia Perez de Perez de Molas ◽  
...  
Keyword(s):  
Protected Areas ◽  
Forest Cover ◽  
Natural Habitat ◽  
Remote Sensing Data ◽  
Rapid Expansion ◽  
Forest Cover Change ◽  
Landsat Images ◽  
Forest Clearing ◽  
Deforestation Rates ◽  
Degree Of Fragmentation

Over the past 40 years, Paraguay has lost the majority of its natural forest cover, thus becoming one of the countries with the highest deforestation rates in the world. The rapid expansion of the agricultural frontier, cattle ranching, and illegal logging between 1987 and 2012 resulted in the loss of 27% of original forest cover, equivalent to almost 44,000 km2. Within this context, the present research provides the first yearly analysis of forest cover change in the Paraguayan Chaco between the years 1987 and 2020. Remote sensing data obtained from Landsat images were applied to derive annual forest cover masks and deforestation rates over 34 years. Part of this study is a comprehensive assessment of the effectiveness of protected areas, as well as an analysis of the degree of fragmentation of the forest. All classification results obtained accuracies above 80% and revealed a total forest cover loss of approximately 64,700 km2. Forest clearing within protected areas was not frequent; however, some natural reserves presented losses of up to 25% of their forest cover. Through the consideration of several landscape metrics, this study reveals an onward fragmentation of forest cover, which endangers the natural habitat of numerous species.

scholarly journals Titling indigenous communities protects forests in the Peruvian Amazon

2017 ◽  
Vol 114 (16) ◽  
pp. 4123-4128 ◽  
Author(s):  
Allen Blackman ◽  
Leonardo Corral ◽  
Eirivelthon Santos Lima ◽  
Gregory P. Asner
Keyword(s):  
Satellite Images ◽  
Forest Cover ◽  
Forest Disturbance ◽  
Indigenous Communities ◽  
Local Communities ◽  
Forest Damage ◽  
Peruvian Amazon ◽  
Forest Clearing ◽  
Indigenous Groups ◽  
High Resolution Satellite Images

Developing countries are increasingly decentralizing forest governance by granting indigenous groups and other local communities formal legal title to land. However, the effects of titling on forest cover are unclear. Rigorous analyses of titling campaigns are rare, and related theoretical and empirical research suggests that they could either stem or spur forest damage. We analyze such a campaign in the Peruvian Amazon, where more than 1,200 indigenous communities comprising some 11 million ha have been titled since the mid-1970s. We use community-level longitudinal data derived from high-resolution satellite images to estimate the effect of titling between 2002 and 2005 on contemporaneous forest clearing and disturbance. Our results indicate that titling reduces clearing by more than three-quarters and forest disturbance by roughly two-thirds in a 2-y window spanning the year title is awarded and the year afterward. These results suggest that awarding formal land titles to local communities can advance forest conservation.

scholarly journals Multi-Level Relationships between Satellite-Derived Nighttime Lighting Signals and Social Media–Derived Human Population Dynamics

2018 ◽  
Vol 10 (7) ◽  
pp. 1128 ◽  
Author(s):  
Ting Ma
Keyword(s):  
Social Media ◽  
Population Dynamics ◽  
Big Data ◽  
Human Activities ◽  
Human Population ◽  
City Size ◽  
Human Settlements ◽  
Good Opportunity ◽  
Nighttime Light ◽  
Multi Level

Satellite-based measurements of the artificial nighttime light brightness (NTL) have been extensively used for studying urbanization and socioeconomic dynamics in a temporally consistent and spatially explicit manner. The increasing availability of geo-located big data detailing human population dynamics provides a good opportunity to explore the association between anthropogenic nocturnal luminosity and corresponding human activities, especially at fine time/space scales. In this study, we used Visible Infrared Imaging Radiometer Suite (VIIRS) day/night band (DNB)–derived nighttime light images and the gridded number of location requests (NLR) from China’s largest social media platform to investigate the quantitative relationship between nighttime light radiances and human population dynamics across China at four levels: the provincial, city, county, and pixel levels. Our results show that the linear relationship between the NTL and NLR might vary with the observation level and magnitude. The dispersion between the two variables likely increases with the observation scale, especially at the pixel level. The effect of spatial autocorrelation and other socioeconomic factors on the relationship should be taken into account for nighttime light-based measurements of human activities. Furthermore, the bivariate relationship between the NTL and NLR was employed to generate a partition of human settlements based on the combined features of nighttime lights and human population dynamics. Cross-regional comparisons of the partitioned results indicate a diverse co-distribution of the NTL and NLR across various types of human settlements, which could be related to the city size/form and urbanization level. Our findings may provide new insights into the multi-level responses of nighttime light signals to human activity and the potential application of nighttime light data in association with geo-located big data for investigating the spatial patterns of human settlement.

scholarly journals The Effectiveness of China’s National Forest Protection Program and National-level Nature Reserves, 2000 to 2010

2013 ◽  
Author(s):  
Guopeng Ren ◽  
Stephen S. Young ◽  
Lin Wang ◽  
Wei Wang ◽  
Yongcheng Long ◽  
...  
Keyword(s):  
Forest Cover ◽  
National Level ◽  
Mainland China ◽  
Canopy Cover ◽  
Nature Reserves ◽  
National Forest ◽  
Natural Forests ◽  
Forest Protection ◽  
Deforestation Rate ◽  
Deforestation Rates

There is profound interest in knowing the degree to which China’s institutions are capable of protecting its natural forests and biodiversity in the face of economic and political change. China’s two most important forest protection policies are its National Forest Protection Program (NFPP) and its National-level Nature Reserves (NNRs). The NFPP was implemented in 17 provinces starting in the year 2000 in response to deforestation-caused flooding. We used MODIS data (MOD13Q1) to estimate forest cover and forest loss across mainland China, and we report that 1.765 million km2or 18.7% of mainland China was covered in forest (12.3%, canopy cover > 70%) and woodland (6.4%, 40% ≤ canopy cover < 70%) in 2000. By 2010, a total of 480,203 km2of forest+woodland was lost, amounting to an annual deforestation rate of 2.7%. The forest-only loss was 127,473 km2, or 1.05% annually. The three most rapidly deforested provinces were outside NFPP jurisdiction, in the southeast. Within the NFPP provinces, the annual forest+woodland loss rate was 2.26%, and the forest-only rate was 0.62%. Because these loss rates are likely overestimates, China appears to have achieved, and even exceeded, its NFPP target of reducing deforestation to 1.1% annually in the target provinces. We also assemble the first-ever polygon dataset for China’s forested NNRs (n=237), which covered 74,030 km2in 2000. Conventional unmatched and covariate-matching analyses both find that about two-thirds of China’s NNRs exhibit effectiveness in protecting forest cover and that within-NNR deforestation rates are higher in provinces that have higher overall deforestation.

scholarly journals Forest and forest succession in Hong Kong, China

1997 ◽  
Vol 13 (6) ◽  
pp. 857-866 ◽  
Author(s):  
Xue Ying Zhuang ◽  
Richard T. Gorlett
Keyword(s):  
Hong Kong ◽  
Forest Cover ◽  
Forest Succession ◽  
Secondary Forest ◽  
Complex Structure ◽  
Detrended Correspondence Analysis ◽  
Feng Shui ◽  
Forest Patches ◽  
Northern Margin ◽  
Current Species

ABSTRACTHong Kong is on the northern margin of the Asian tropics. The original forest cover was cleared centuries ago but secondary forest has developed since 1945 at many sites protected from fire and cutting. There are also older forest patches maintained behind villages for reasons of ‘feng shui’, the Chinese system of geomancy. All plants >2 cm dbh were identified and measured in forty-four 400-m2 plots. Detrended correspondence analysis showed a floristic continuum, with the montane sites (>500 m) most distinct and some overlap between lowland post-1945 secondary forest and the feng shui woods. The 30–40 year-old secondary forest is dominated by Persea spp. Montane forest is similar but lacks several common lowland taxa of tropical genera and includes more subtropical taxa. The feng shui woods have the most complex structure and contain some tree species not found in other forest types. Their origin and history is obscure but we suggest that both planting and selective harvesting have had a role in their current species composition

Landscape fragmentation

2010 ◽  
Author(s):  
Ned Horning ◽  
Julie A. Robinson ◽  
Eleanor J. Sterling ◽  
Woody Turner ◽  
Sacha Spector
Keyword(s):  
Forest Fragmentation ◽  
Landscape Metrics ◽  
Forest Cover ◽  
Remotely Sensed ◽  
Clear Understanding ◽  
Remotely Sensed Data ◽  
Deforestation Rates ◽  
Habitat Conversion ◽  
Conservation Organizations ◽  
Total Core Area

The country of Vietnam has long been recognized as an important region for biodiversity (Sterling et al. 2006). High-profile discoveries in the 1990s of many species new to science including large ones such as the Saola (Pseudoryx nghetinhensis), an 85 kg basal member of the cattle subfamily Bovinae and the first new genus of large land-dwelling mammal described since the okapi (Okapia johnstoni) in 1901, have focused the attention of national and international conservation organizations on Vietnam and surrounding countries in mainland Southeast Asia (Hurley et al. in prep.). Conservation action for these endemic, endangered species relies on a clear understanding of trends in habitat conversion. To track deforestation rates through time in Vietnam, Meyfroidt and Lambin (2008) combined remotely sensed data with landscape metrics such as number of patches, mean patch size, mean proximity index, and total core area index. They tested their analyses across a variety of land cover studies including those using Advanced Very High Resolution Radiometer (AVHRR), Landsat, SPOT, and MODIS data sources. They found that forest cover decreased nationally from the 1980s to the 1990s and then showed an increase between 1990 and 2000, due to plantation forests as well as natural forest regeneration. However, the effects of this forest transition on fragmentation metrics noted above differed across the country. For instance, in some places, such as central Vietnam where forest cover is relatively large and well connected, reforestation led to a decrease in forest fragmentation and secondary forests recovered rapidly. However in others, such as areas in the north where forest fragmentation dates back centuries and forests have therefore long been isolated, reforestation did not seem to have an impact on continued fragmentation and habitat loss. In this chapter we detail the importance of fragmentation and landscape metrics to ecology and conservation, outlining when and where remotely sensed data can help in these analyses. We then discuss a subset of fragmentation metrics and point to some challenges in processing fragmentation data. We provide examples of composition and connectivity metrics illuminated with examples from the remote sensing literature.

Forest cover change patterns in Myanmar (Burma) 1990–2000

2005 ◽  
Vol 32 (4) ◽  
pp. 356-364 ◽  
Author(s):  
PETER LEIMGRUBER ◽  
DANIEL S. KELLY ◽  
MARC K. STEININGER ◽  
JAKE BRUNNER ◽  
THOMAS MÜLLER ◽  
...  
Keyword(s):  
Forest Cover ◽  
Mangrove Forests ◽  
Forest Cover Change ◽  
Charcoal Production ◽  
Important Species ◽  
Agricultural Conversion ◽  
Deforestation Rates ◽  
Commercial Logging ◽  
Closed Canopy ◽  
Landsat Satellite

Myanmar is one of the most forested countries in mainland South-east Asia. These forests support a large number of important species and endemics and have great value for global efforts in biodiversity conservation. Landsat satellite imagery from the 1990s and 2000s was used to develop a countrywide forest map and estimate deforestation. The country has retained much of its forest cover, but forests have declined by 0.3% annually. Deforestation varied considerably among administrative units, with central and more populated states and divisions showing the highest losses. Ten deforestation hotspots had annual deforestation rates well above the countrywide average. Major reasons for forest losses in these hotspots stemmed from increased agricultural conversion, fuelwood consumption, charcoal production, commercial logging and plantation development. While Myanmar continues to be a stronghold for closed canopy forests, several areas have been experiencing serious deforestation. Most notable are the mangrove forests in the Ayeyarwady delta region and the remaining dry forests at the northern edge of the central dry zone.

scholarly journals Which is worse for the red-billed curassow: habitat loss or hunting pressure?

Oryx ◽  
2020 ◽  
pp. 1-9
Author(s):  
Elaine Rios ◽  
Philip J. K. McGowan ◽  
Nigel J. Collar ◽  
Maíra Benchimol ◽  
Gustavo R. Canale ◽  
...  
Keyword(s):  
Habitat Loss ◽  
Habitat Quality ◽  
Forest Cover ◽  
Explanatory Power ◽  
Forest Patches ◽  
Hunting Pressure ◽  
North East ◽  
Forest Remnants ◽  
The Status ◽  
Patch Density

Abstract Large ground-dwelling Neotropical gamebirds are highly threatened by habitat loss and hunting, but conservationists rarely attempt to distinguish between these two threats in the management of populations. We used three different types of species records to determine the status (i.e. persistence level) of the Endangered red-billed curassow Crax blumenbachii in 14 forest remnants in north-east Brazil, as either persistent, precarious or extirpated. We related these persistence levels to variables measured in a 2-km buffer radius, including variables associated with habitat quality (proportion of forest cover, length of rivers, patch density, distance from rivers) and hunting pressure (proportion of cacao agroforests and farmlands, length of roads, total area occupied by settlements, distance from roads and from settlements). Curassows were more persistent in forest patches located (1) more distant from settlements, (2) in landscapes with few settlements, (3) in landscapes with a high incidence of roads, (4) in a mosaic with a high proportion of forest, shaded cacao agroforest and farmland, and (5) more distant from other forest patches. Hunting pressure potentially exerts more influence on persistence than habitat quality: (1) hunting pressure submodels had a higher explanatory power than habitat quality submodels, (2) final models comprised four hunting pressure variables but only two habitat quality variables, and (3) hunting pressure variables appeared in all models whereas habitat quality variables appeared in only one final model. If hunting pressure is driving declines in curassows, regions with low human presence and a high proportion of forest cover are recommended for establishing new reserves.

scholarly journals The state of lemur conservation in south-eastern Madagascar: population and habitat assessments for diurnal and cathemeral lemurs using surveys, satellite imagery and GIS

Oryx ◽  
2005 ◽  
Vol 39 (2) ◽  
pp. 204-218 ◽  
Author(s):  
Mitchell T. Irwin ◽  
Steig E. Johnson ◽  
Patricia C. Wright
Keyword(s):  
Information System ◽  
Population Density ◽  
Satellite Images ◽  
Forest Cover ◽  
Geographical Information ◽  
Human Populations ◽  
Ecological Diversity ◽  
Geographic Ranges ◽  
South Eastern ◽  
Face Threats

The unique primates of south-eastern Madagascar face threats from growing human populations. The country's extant primates already represent only a subset of the taxonomic and ecological diversity existing a few thousand years ago. To prevent further losses remaining taxa must be subjected to effective monitoring programmes that directly inform conservation efforts. We offer a necessary first step: revision of geographic ranges and quantification of habitat area and population size for diurnal and cathemeral (active during both day and night) lemurs. Recent satellite images are used to develop a forest cover geographical information system, and censuses are used to establish range boundaries and develop estimates of population density and size. These assessments are used to identify regions and taxa at risk, and will be a useful baseline for future monitoring of habitat and populations. Precise estimates are impossible for patchily-distributed taxa (especially Hapalemur aureus, H. simus and Varecia variegata variegata); these taxa require more sophisticated modelling.

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