云南西双版纳地区森林转型特征(英文)

森林转型是指森林覆盖率由净减少到净增加的过程。中国森林早在20世纪80年代就进入了转型期,然而,中国热带地区的总森林覆盖率虽呈增长趋势,但依旧存在着天然林大量被毁的现象。鉴于天然林对森林生态系统功能的重要作用,本研究通过加入森林类型分类的内容,以西双版纳为例探讨其森林转型的真实特征。结果表明:森林转型理论单纯以"总森林"覆盖率为研究对象,忽视了其他森林类型的动态变化,甚至掩盖了"天然林"的真实动态变化。西双版纳的森林转型主要是人工种植林的扩张所致,只是树木数量统计上的转型。事实上,自1988年以来,西双版纳的天然林一直在锐减。所以建议未来关于森林转型的研究应将"森林"区分成不同的森林类型加以研究。     

西双版纳土地利用/覆盖变化与地形的关系

 土地利用/覆盖变化是全球变化研究的重要领域。该文利用6个时期的MSS/TM/ETM影像和1:50 000DEM数据分析了1976~2007年西双版纳地区不同地形下的土地利用/覆盖变化动态, 结果表明: 1)31年间, 该区土地利用/覆盖变化剧烈, 有林地面积由1976年的69.0%下降到2007年的43.6%, 橡胶园面积由1976年的1.3%增加到2007年的11.8%; 2)有林地在海拔1 600 m以下不断减少, 而橡胶园的海拔分布上限则持续增加, 由1976年的1 000 m上升至2007年的1 400 m, 面积在400~1 000 m处占优。农业用地主要分布在海拔400～600 m, 在600 m之上迅速减少; 3)各坡度带上的有林地面积逐年减少, 橡胶园则逐年增加, 而灌木林与旱地则先升后降; 橡胶园、农业用地等主要分布在坡度较缓的区域, 坡度越大, 有林地越多; 1988年后, 橡胶园面积在坡度5°以下基本保持不变, 但在坡度大于5°的区域持续扩张; 4)坡向对橡胶园与农业用地等分布的影响较大, 南坡的橡胶发展最为迅速, 且有向北坡发展的趋势。有林地在北坡分布比例较大, 旱地在北坡分布比例较小。人口增加与橡胶园和茶园等经济种植园的不断扩展是导致西双版纳土地利用/覆盖变化的直接因素。要实现西双版纳的可持续发展, 必须控制经济种植园的盲目扩张, 科学合理垦殖, 保护热带森林。     

Demand for rubber is causing the loss of high diversity rain forest in SW China

As the economies of developing countries grow, and the purchasing power of their inhabitants increases, the pressure on the environment and natural resources will continue to increase. In the specific case of China, impressive economic growth during the last decades exemplifies this process. Specifically, we focus on how changing economic dynamics are influencing land-use and land-cover change in Xishuangbanna, China. Xishuangbanna has the richest flora and fauna of China, but increasing demand for natural rubber and the expansion of rubber plantations is threatening this high-diversity region. We quantified land-use/land-cover change across Xishuangbanna using Landsat images from 1976, 1988, and 2003. The most obvious change was the decrease in forest cover and an increase in rubber plantations. In 1976, forests covered approximately 70% of Xishuangbanna, but by 2003 they covered less than 50%. Tropical seasonal rain forest was the forest type most affect by the expansion of rubber plantations, and a total of 139,576 ha was lost. The increase of rubber plantations below 800 m, shifted agricultural activities to higher elevations, which resulted in deforestation of mountain rain forest and subtropical evergreen broadleaf forest. Although these changes have affected the biodiversity and ecosystem services, we believe that long-term planning and monitoring can achieve a balance between economic and social needs of a growing population and the conservation of a highly diverse flora and fauna. Below 800 m , we recommend that no more rubber plantations be established, existing forest fragments should be protected, and riparian forests should be restored to connect fragments. Future rubber plantations should be established in the abandoned arable or shrublands at higher elevations, and tea or other crops should be planted in the understory to improve economic returns and reduce erosion.     

Impacts of forest cover change on ecosystem services in high Andean mountains

Land conversion affects the delivery of ecosystem goods and services. In this study, we used a 50 years time series of land cover maps to assess the potential impacts of forest cover changes on ecosystem services. A multi-source data integration strategy was followed to reduce inconsistencies in land cover change detection that result from the comparison of historical aerial photographs and satellite images. Our forest cover change analysis highlighted a shift from net deforestation to net reforestation in the early 1990s, consistent with the forest transition theory. When taking the nature of forest cover changes into account, our data show that the areal increase of the forested area was not associated with an improvement in ecological conditions. The overall capacity of the landscape to deliver ecosystem services dropped steadily by 16% over the 50 years’ study period. Conversion of native forests to agricultural land was associated with the strongest decline in ecosystem services. Conversion of natural grasslands into pine plantations mostly led to negative and probably irreversible impacts on the delivery of ecosystem services. Conversion of degraded agricultural lands into pine plantations led to an improvement in ecological conditions. An effective spatial targeting of forestation programs has the potential to maximize the environmental benefits that forest plantations may offer while minimizing their environmental harm.     

Rehabilitation of degraded forests in Thailand: policy and practice

Thailand has suffered from severe deforestation during the last century. Forest cover has declined drastically both in terms of area and quality, mostly due to the expansion of human activities. Much of the deforested area has been used for agricultural purposes, but much has also been left in a degraded condition. In late 1980s, the forest declined to a point where the nation decided that the remaining forest should be kept for conservation rather than further exploitation. Consequently, forest policy has shifted its focus from exploitation to sustainable management and protection. Thailand has set a goal of increasing its forest area to 40% of the total land area, while at present, forests occupy around 28.9% of the land. With the intention to retain most of the remaining forest as protected areas and, at the same time, achieve the goal set, several reforestation and rehabilitation initiatives have been implemented, especially on those lands in a degraded condition. This paper focuses on the significant issues affecting both the policy and practice of forest rehabilitation. Given that the large number of people whose livelihood depends on the forests for subsistence and other purposes normally has been excluded from the decision-making process in forest management, most important among these issues are the integration of the socio-economic and environmental needs into rehabilitation initiatives together with the active participation of local communities in the rehabilitation program. Case studies of reforestation and rehabilitation initiatives are also discussed.     

南滚河流域土地利用变化对亚洲象生境的影响

土地利用变化对亚洲象生境影响显著,明晰其影响机制是有效保护亚洲象的前提。为探明土地利用变化对亚洲象生境影响的时空过程及机制,以亚洲象残存的中-缅跨境流域-南滚河流域为例,在1988和2018年两期Landsat土地利用/土地覆被遥感分类图的基础上,采用LandTrendr算法检测30年间流域土地利用变化引起的天然林扰动,结合生态位因子分析（ENFA）模型评定的亚洲象生境适宜性分布,探究以天然林扰动为主的土地利用变化对亚洲象生境的影响。结果表明：（1）1988-2018年间,南滚河流域土地利用变化主要为天然林转化为其他地类,且天然林扰动强度在中、缅境内差异明显;（2）以橡胶种植扩张导致毁林为主的土地利用变化造成南滚河流域亚洲象生境萎缩,生境斑块间连通性降低,破碎化程度较高;（3）该流域亚洲象生境丧失过程表现为由边缘向内部逐渐被蚕食,适宜生境最终被分割为上、下游两个相互孤立的子区域。因此,抑制以橡胶林为主的热作种植扩张,恢复上、下游生境连通性,建立流域尺度的跨境保护区,是实现南滚河流域亚洲象种群保护和缓解人象冲突的重要途径。     

Evidence of incipient forest transition in southern Mexico

Case studies of land use change have suggested that deforestation across Southern Mexico is accelerating. However, forest transition theory predicts that trajectories of change can be modified by economic factors, leading to spatial and temporal heterogeneity in rates of change that may take the form of the Environmental Kuznets Curve (EKC). This study aimed to assess the evidence regarding potential forest transition in Southern Mexico by classifying regional forest cover change using Landsat imagery from 1990 through to 2006. Patterns of forest cover change were found to be complex and non-linear. When rates of forest loss were averaged over 342 municipalities using mixed-effects modelling the results showed a significant (p<0.001) overall reduction of the mean rate of forest loss from 0.85% per year in the 1990-2000 period to 0.67% in the 2000-2006 period. The overall regional annual rate of deforestation has fallen from 0.33% to 0.28% from the 1990s to 2000s. A high proportion of the spatial variability in forest cover change cannot be explained statistically. However analysis using spline based general additive models detected underlying relationships between forest cover and income or population density of a form consistent with the EKC. The incipient forest transition has not, as yet, resulted in widespread reforestation. Forest recovery remains below 0.20% per year. Reforestation is mostly the result of passive processes associated with reductions in the intensity of land use. Deforestation continues to occur at high rates in some focal areas. A transition could be accelerated if there were a broader recognition among policy makers that the regional rate of forest loss has now begun to fall. The changing trajectory provides an opportunity to actively restore forest cover through stimulating afforestation and stimulating more sustainable land use practices. The results have clear implications for policy aimed at carbon sequestration through reducing deforestation and enhancing forest growth.     

Deforestation and Reforestation of Latin America and the Caribbean (2001–2010)

Forest cover change directly affects biodiversity, the global carbon budget, and ecosystem function. Within Latin American and the Caribbean region (LAC), many studies have documented extensive deforestation, but there are also many local studies reporting forest recovery. These contrasting dynamics have been largely attributed to demographic and socio‐economic change. For example, local population change due to migration can stimulate forest recovery, while the increasing global demand for food can drive agriculture expansion. However, as no analysis has simultaneously evaluated deforestation and reforestation from the municipal to continental scale, we lack a comprehensive assessment of the spatial distribution of these processes. We overcame this limitation by producing wall‐to‐wall, annual maps of change in woody vegetation and other land‐cover classes between 2001 and 2010 for each of the 16,050 municipalities in LAC, and we used nonparametric Random Forest regression analyses to determine which environmental or population variables best explained the variation in woody vegetation change. Woody vegetation change was dominated by deforestation (?541,835 km²), particularly in the moist forest, dry forest, and savannas/shrublands biomes in South America. Extensive areas also recovered woody vegetation (+362,430 km²), particularly in regions too dry or too steep for modern agriculture. Deforestation in moist forests tended to occur in lowland areas with low population density, but woody cover change was not related to municipality‐scale population change. These results emphasize the importance of quantitating deforestation and reforestation at multiple spatial scales and linking these changes with global drivers such as the global demand for food.     

Forest ecosystem restoration due to a national conservation plan in China

China has a long history of large-scale deforestation that has contributed to serious consequences such as frequent geological disaster, flood and soil erosion. It was only recently that forest management strategy shifted from the traditional harvesting orientation to a more balanced forest ecosystem management approach with a focus on conservation. To understand the effects of such a shift, on the forest dynamics especially since the implementation of Natural Forest protection Project (NFPP), this paper examined the case of Lushuihe region, a typical region of the northeast China forest zone. Land use and landscape pattern for the period of 1975-2007 were analyzed based on Landsat MSS and TM images. Net primary, productivity (NPP), estimated with the CASA productivity model, was used to assess the human impacts on the forest ecosystem function. The results showed a reversing trend of forest cover since 1988, from continuous decrease to rather rapid increase. From 1975 to 1988, due to reckless deforestation, the forest cover in the case region decreased about 10439.39 ha (8.54% of the study area). Forest cover of the region recovered from 77.68% in 1988 to 89.56% in 1999 and 92.33% in 2007. While the forest cover increased, landscape metrics indicate that human disturbance significantly altered the composition and structure of the forest landscape. NPP change indicated a continued decreasing trend until 2007, albeit at a slower pace since 1988. In 2007, while the decreasing trend of NPP was reversed, the forest structure was still inferior to that of 1975. Looking forward, diversifying and securing the livelihoods of the still growing local population that have been heavily dependent on the traditional forestry industry remain one of the key challenges as well as solutions for enhancing and managing the regional forest ecosystem structure and function in the region.     

Forest transition in Vietnam and its environmental impacts

This study assesses the presence of a forest transition – that is, a shift from net deforestation to net reforestation – in Vietnam during the 1990s, and describes its key attributes relevant for global environmental change issues. Using Fuzzy Kappa and other indicators, we compared forest cover estimates and spatial patterns from global and national land cover maps from the early and late 1990s, and compiled other available statistics for years before and after that period. This showed that a forest transition indeed occurred in Vietnam: the forest cover dropped to 25–31% of the country area in 1991–1993, and then increased to 32–37% in 1999–2001. The reforestation occurred at a higher rate than deforestation in the previous decades, and was due in similar proportions, to natural forest regeneration and to planted forests. The carbon stock in forests followed a similar transition, decreasing to 903 (770–1307) Tg C in 1991–1993, and then increasing to 1374 (1058–1744) Tg C in 2005. However, forest density declined during the same period, with an increasing proportion of young and degraded forests. The effects on habitats measured with landscape pattern indices were contrasted: in several regions, the reforestation decreased forest fragmentation, while in others, clearing of old‐growth forests continued and/or forest fragmentation increased. This shows that a transition in forest area is not sufficient to rehabilitate the different ecosystem functions and services of forests. Other forest transitions exist in Tropical Asia and in Latin America. Knowledge about the causes, pattern and environmental impacts of the forest transition in Vietnam is therefore relevant to understand possible emerging regional trends that would have implications for global environmental change.     

森林退化/衰退的研究与实践

森林退化可以理解为森林面积减少、结构丧失、质量降低、功能下降;森林衰退则是森林退化的一种形式,指森林（树木）在生长发育过程中出现的生理机能下降、生长发育滞缓、生产力降低甚至死亡,以及地力衰退等状态.国内外研究表明,森林采伐/毁林是造成森林面积减少的最主要原因,有关森林采伐/毁林引起的森林退化研究主要集中在森林退化的后果、国家/国际政策的影响、加强全球性合作以及寻求解决途径等方面.森林衰退原因可归纳为：工、农业污染,自然胁迫/致衰因子,林分动态发生变化,森林衰退病或生态病,人工纯林以及纯林连栽导致的地力、生产力衰退等.中国的森林退化/衰退现状与世界各地森林退化基本一致,但由于历史原因,中国森林退化又有其自身特点：近一个世纪的强烈人为干扰,使大部分原始天然林退化为次生林;中国拥有世界上最多的人工林,且多数人工林均具有质量差、功能低等衰退特征.本文在综述森林退化/衰退研究与实践基础上,提出中国现代森林退化/衰退的的主要原因,给出中国森林退化/衰退的基本对策.     

中国天然林保护工程区森林覆盖遥感监测

天然林资源保护工程（天保工程）自1998年开始实施至2020年底结束,标志着我国林业由以木材生产为主向以生态建设为主进行转变,对天然林资源开展定量监测与评估,有助于全面、及时、科学地评价天保工程对森林资源的保护成效。基于公开发布的土地覆盖产品,利用新的遥感数据合成算法构建了森林类型综合提升方法,生产了一套我国天保工程区的森林覆盖产品,对天保工程区1997年至2020年间的森林覆盖情况开展监测与评估。利用中国森林生态系统定位研究网络数据（CFERN）、森林资源规划设计调查数据和地面调查数据进行精度检验,森林类型的分类精度优于90%。分析结果显示,自天保工程实施以来,工程区的森林覆盖度总体呈恢复性增长趋势,森林覆盖从1997年的30.15%增长到2020年的31.74%,净增长1.59%,其中,长江上游地区森林增长量最高,占全工程区森林增长面积的50.97%。研究结果表明我国天保工程区内森林资源得到有效保护和恢复,天保工程实施效果显著。     

Expanding temporal resolution in landscape transformations: Insights from a landsat-based case study in Southern Chile

Understanding temporal and spatial dimensions of land cover dynamics is a critical factor to link ecosystem transformation to land and environmental management. The trajectory of land cover change is not a simple difference between two conditions, but a continuous process. Therefore, there is a need to integrate multiple time periods to identify slow and rapid transformations over time. We mapped land cover composition and configuration changes using time series of Landsat TM/ETM+ images (1985–2011) in Southern Chile to understand the transformation process of a temperate rainforest relict and biodiversity hotspot. Our analysis builds on 28 Landsat scenes from 1985 to 2011 that have been classified using a random forests approach. Base on the high temporal data set we quantify land cover change and fragmentation indices to fully understand landscape transformation in this area. Our results show a high deforestation process for old growth forest strongest at the beginning of the study period (1985–1986–1998–1999) followed by a progressive slowdown until 2011. Within different study periods deforestation rates were much larger than the average rate over the complete study period (0.65%), with the highest annual deforestation rate of 1.2% in 1998–1999. The deforestation resulted in a low connectivity between native forest patches. Old-growth forest was less fragmented, but was concentrated mainly in two large regions (the Andes and Coastal mountain range) with almost no connection in between. Secondary forest located in more intensively used areas was highly fragmented. Exotic forest plantation areas, one of the most important economic activities in the area, increased sevenfold (from 12,836 to 103,540 ha), especially during the first periods at the expense of shrubland, secondary forest, grassland/arable land and old grown forest. Our analysis underlines the importance of expanding temporal resolution in land cover/use change studies to guide sustainable ecosystem management strategies as increase landscape connectivity and integrate landscape planning to economic activities. The study is highlighting the key role of remote sensing in the sustainable management of human influenced ecosystems.     

基于森林资源清查资料的落叶松林生物量和净生长量估算模式

 丰富的森林资源清查资料是了解各类森林材积准确信息的重要途径,如果能将这些资源用于估算森林生物量和生产力的动态变化,不仅对于科学地指导森林的经营管理,而且对于全球变化的研究,特别是区域尺度的生产力模型验证,都具有重要意义。根据我国落叶松(Larix)林生物量和材积的实际调查资料,探讨了基于森林资源清查资料(森林材积V和林龄A)估算森林生物量和生产力的方法,指出无论是人工林还是天然林,落叶松林的生物量与其蓄积量、生产力与其年均净生物生产量(B/A)和年均净蓄积生产量(V/A)均呈双曲线关系,但落叶松林的生产力与其生物量(B)关系不明显,并分别建立了人工和天然落叶松林的相关模型;所建模型克服了将森林生物量与其蓄积量之比作为常数的不足,并考虑了林龄对于森林生产力的影响。     

北京地区不同地形条件下的土地覆盖动态

利用MSS/TM影像和1∶250 000 高程数据分析了1978~2001年北京地区土地覆盖的变化。为研究人类活动对土地覆盖类型及植被变化的影响,根据植被的分布规律和人类活动影响,利用数字高程模型(DEM)将研究区遥感影像分为不同海拔段,分别建立标志进行解译。通过转移概率矩阵计算、不同地形因子影响下的土地覆盖类型分布的GIS分析,得到如下结果:1) 1978~2001年间北京市土地覆盖变化主要发生在平原和低海拔、小坡度的平缓地区,表现为农业用地向城镇用地的转变;高海拔地区主要为天然植被所覆盖,土地覆盖变化相对较小,主要是灌丛向林地的转变。2) 地形因子显著影响土地覆盖类型的分布及变化。随着海拔的升高和坡度的增大,农业用地和城镇用地减少,林地和灌丛逐渐增加。坡向对植被的分布也有较大影响。     

Anthropogenic activities dominated tropical forest carbon balance in two contrary ways over the Greater Mekong Subregion in the 21st century

The tropical forest carbon (C) balance threatened by extensive socio-economic development in the Greater Mekong Subregion (GMS) in Asia is a notable data gap and remains contentious. Here we generated a long-term spatially quantified assessment of changes in forests and C stocks from 1999 to 2019 at a spatial resolution of 30 m, based on multiple streams of state-of-the-art high-resolution satellite imagery and in situ observations. Our results show that (i) about 0.54 million square kilometers (21.0% of the region) experienced forest cover transitions with a net increase in forest cover by 4.3% (0.11 million square kilometers, equivalent to 0.31 petagram of C [Pg C] stocks); (ii) forest losses mainly in Cambodia, Thailand, and in the south of Vietnam, were also counteracted by forest gains in China due mainly to afforestation; and (iii) at the national level during the study period an increase in both C stocks and C sequestration (net C gain of 0.087 Pg C) in China from new plantation, offset anthropogenetic emissions (net C loss of 0.074 Pg C) mainly in Cambodia and Thailand from deforestation. Political, social, and economic factors significantly influenced forest cover change and C sequestration in the GMS, positively in China while negatively in other countries, especially in Cambodia and Thailand. These findings have implications on national strategies for climate change mitigation and adaptation in other hotspots of tropical forests.     

Plantation forests and biodiversity: oxymoron or opportunity?

Losses of natural and semi-natural forests, mostly to agriculture, are a significant concern for biodiversity. Against this trend, the area of intensively managed plantation forests increases, and there is much debate about the implications for biodiversity. We provide a comprehensive review of the function of plantation forests as habitat compared with other land cover, examine the effects on biodiversity at the landscape scale, and synthesise context-specific effects of plantation forestry on biodiversity. Natural forests are usually more suitable as habitat for a wider range of native forest species than plantation forests but there is abundant evidence that plantation forests can provide valuable habitat, even for some threatened and endangered species, and may contribute to the conservation of biodiversity by various mechanisms. In landscapes where forest is the natural land cover, plantation forests may represent a low-contrast matrix, and afforestation of agricultural land can assist conservation by providing complementary forest habitat, buffering edge effects, and increasing connectivity. In contrast, conversion of natural forests and afforestation of natural non-forest land is detrimental. However, regional deforestation pressure for agricultural development may render plantation forestry a ‘lesser evil’ if forest managers protect indigenous vegetation remnants. We provide numerous context-specific examples and case studies to assist impact assessments of plantation forestry, and we offer a range of management recommendations. This paper also serves as an introduction and background paper to this special issue on the effects of plantation forests on biodiversity.

Discerning Fragmentation Dynamics of Tropical Forest and Wetland during Reforestation,Urban Sprawl,and Policy Shifts

Despite the overall trend of worldwide deforestation over recent decades, reforestation has also been found and is expected in developing countries undergoing fast urbanization and agriculture abandonment. The consequences of reforestation on landscape patterns are seldom addressed in the literature, despite their importance in evaluating biodiversity and ecosystem functions. By analyzing long-term land cover changes in Puerto Rico, a rapidly reforested (6 to 42% during 1940–2000) and urbanized tropical island, we detected significantly different patterns of fragmentation and underlying mechanisms among forests, urban areas, and wetlands. Forest fragmentation is often associated with deforestation. However, we also found significant fragmentation during reforestation. Urban sprawl and suburb development have a dominant impact on forest fragmentation. Reforestation mostly occurs along forest edges, while significant deforestation occurs in forest interiors. The deforestation process has a much stronger impact on forest fragmentation than the reforestation process due to their different spatial configurations. In contrast, despite the strong interference of coastal urbanization, wetland aggregation has occurred due to the effective implementation of laws/regulations for wetland protection. The peak forest fragmentation shifted toward rural areas, indicating progressively more fragmentation in forest interiors. This shift is synchronous with the accelerated urban sprawl as indicated by the accelerated shift of the peak fragmentation index of urban cover toward rural areas, i.e., 1.37% yr⁻¹ in 1977–1991 versus 2.17% yr⁻¹ in 1991–2000. Based on the expected global urbanization and the regional forest transition from deforested to reforested, the fragmented forests and aggregated wetlands in this study highlight possible forest fragmentation processes during reforestation in an assessment of biodiversity and functions and suggest effective laws/regulations in land planning to reduce future fragmentation.     

西双版纳勐仑地区景观格局变化定量分析

利用景观空间格局定量化分析软件FRAGSTATS和西双版纳勐仑地区1988、2003年两期Landsat影像解译结果,定量分析和比较了两时期景观格局的组成、各类型斑块特征、不同类型斑块间空间分布关系及其动态变化,并进一步分析了其生态效应.结果表明,15年来研究区内以经济林为主的人工景观组分剧烈增加,景观多样性上升;橡胶园等人工种植园地的扩张使得有林地破碎化：平均斑块面积由44km2减至21km2,斑块数由368增至441,同时边缘密度增加;导致其核心区缩小,斑块连接度下降;城镇建设用地的扩展也使得耕地（主要是水田）趋于破碎化.景观中不同斑块的交错分布格局也趋于简单.人工经济林的大面积发展和城市化使该区景观中人为影响显著增强,并产生了生物生境恶化及生态环境质量下降等不良生态效应.未来土地利用规划中应借鉴景观生态学原则,以尽量减少对生态环境的进一步破坏.     

National forest cover change in Congo Basin: deforestation,reforestation, degradation and regeneration for the years 1990, 2000 and 2005

This research refers to an object‐based automatic method combined with a national expert validation to produce regional and national forest cover change statistics over Congo Basin. A total of 547 sampling sites systematically distributed over the whole humid forest domain are required to cover the six Central African countries containing tropical moist forest. High resolution imagery is used to accurately estimate not only deforestation and reforestation but also degradation and regeneration. The overall method consists of four steps: (i) image automatic preprocessing and preinterpretation, (ii) interpretation by national expert, (iii) statistic computation and (iv) accuracy assessment. The annual rate of net deforestation in Congo Basin is estimated to 0.09% between 1990 and 2000 and of net degradation to 0.05%. Between 2000 and 2005, this unique exercise estimates annual net deforestation to 0.17% and annual net degradation to 0.09%. An accuracy assessment reveals that 92.7% of tree cover (TC) classes agree with independent expert interpretation. In the discussion, we underline the direct causes and the drivers of deforestation. Population density, small‐scale agriculture, fuelwood collection and forest's accessibility are closely linked to deforestation, whereas timber extraction has no major impact on the reduction in the canopy cover. The analysis also shows the efficiency of protected areas to reduce deforestation. These results are expected to contribute to the discussion on the reduction in CO₂ emissions from deforestation and forest degradation (REDD+) and serve as reference for the period.