Tropical deforestation is a key contributor to species extinction and climate change, yet the extent of tropical forests and their rate of destruction and degradation through fragmentation remain ...poorly known. Madagascar's forests are among the most biologically rich and unique in the world but, in spite of longstanding concern about their destruction, past estimates of forest cover and deforestation have varied widely. Analysis of aerial photographs (c. 1953) and Landsat images (c. 1973, c. 1990 and c. 2000) indicates that forest cover decreased by almost 40% from the 1950s to c. 2000, with a reduction in ‘core forest’ > 1 km from a non-forest edge of almost 80%. This forest destruction and degradation threaten thousands of species with extinction. Country-wide coverage of high-resolution validated forest cover and deforestation data enables the precise monitoring of trends in habitat extent and fragmentation critical for assessment of species' conservation status.
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.
Time series of multi-spectral satellite data are a valuable option for crop-area monitoring, in particular by enabling rapid, accurate, and consistent estimation of crop area. In this study, we ...demonstrate the use of a turn-key wheat area mapping model using growing season Landsat time-series data to improve the precision of area estimates produced from a sample of field locations at which the presence of percent wheat per sample pixel was determined. The strata used in the sampling design to obtain the current season's in-situ reference data were created from a wheat map of the previous growing season. We then used a map for the current growing season to serve as an auxiliary variable in a regression estimator of the wheat area. This approach allows for rapid production of such maps and area estimates with less demand for technical expertise in an ongoing wheat monitoring system. Our automated, turn-key classification-tree algorithm produced wheat maps with comparable overall accuracy to those achieved by traditional supervised classification using manual training data collection. Pixel counts from turn-key maps for the years 2013 to 2017 over-estimated wheat area by 0.86% in 2014 to 7.26% in 2017 when compared to the official estimate from the Punjab Crop Reporting Service. Of the several approaches to estimating wheat area were compared, stratified random and simple random sampling augmented by a regression estimator were the two that yielded the smallest standard errors. Incorporating a current season, turn-key map in a regression estimator with data from a simple random sampling design represents a methodologically straightforward, operational implementation of timely, accurate, and precise monitoring of wheat area. Given the importance of wheat production in Punjab to Pakistan's national economy, this method represents an operationally efficient and effective monitoring of inter-annual shortages or surpluses in support of grain management. An automated, turn-key winter wheat mapping algorithm enables timely area estimation in advance of harvest.
Remote sensing is increasingly used by policy-makers and conservationists to identify conservation priorities and changes in land cover. This is particularly important in the biodiverse tropics, ...where there are often few field data. Conservation action is often directed towards areas containing globally threatened species, but there have been few attempts to improve assessments of species’ extinction risk through remote sensing. Here, in a novel approach we use deforestation estimates, measured through satellite imagery, to assess the conservation status of an entire endemic avifauna, based on IUCN Red List criteria. The island of New Britain, east of New Guinea, is of very high global conservation importance, and home to 37 endemic or restricted-range bird species. Analysis suggests 12% of forest cover was lost between 1989 and 2000, including over 20% of forest under 100
m altitude, with substantial areas cleared for commercial oil palm plantations. Application of the IUCN Red List criteria to these new data on area of remaining forest and rates of deforestation indicates that many species are more threatened than previously realised, with the total number of threatened or near threatened species increasing from 12 to 21. Thus, this study highlights the urgency of establishing and effectively managing protected areas in suitable lowland forests of New Britain. More broadly, it demonstrates another potential of remote sensing to assist strategic conservation decisions.
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.
Land-cover change in eastern lowland Bolivia was documented using Landsat images from five epochs for all landscapes situated below the montane tree line at approximately 3000 m, including humid ...forest, inundated forest, seasonally dry forest, and cloud forest, as well as scrublands and grasslands. Deforestation in eastern Bolivia in 2004 covered 45 411 km2, representing ∼9% of the original forest cover, with an additional conversion of 9042 km2 of scrub and savanna habitats representing 17% of total historical land-cover change. Annual rates of land-cover change increased from ∼400 km2 y−1 in the 1960s to ∼2900 km2 y−1 in the last epoch spanning 2001 to 2004. This study provides Bolivia with a spatially explicit information resource to monitor future land-cover change, a prerequisite for proposed mechanisms to compensate countries for reducing carbon emissions as a result of deforestation. A comparison of the most recent epoch with previous periods shows that policies enacted in the late 1990s to promote forest conservation had no observable impact on reducing deforestation and that deforestation actually increased in some protected areas. The rate of land-cover change continues to increase linearly nationwide, but is growing faster in the Santa Cruz department because of the expansion of mechanized agriculture and cattle farms.
We documented the history of land-use change and migration in eastern Bolivia in five temporal periods: pre-1976, 1976–1986, 1986–1991, 1991–2001, and 2001–2004. We included all land-cover types ...located below the natural montane tree line (∼3000 m), including forest, savanna, scrubland, seasonal wetland, second-growth forest, pasture, and cropland. The rate of land-use change has increased from approximately 4.7 × 10⁴ ha/yr in the 1960s to > 2.9 × 10⁵ ha/yr in the most recent period. Land-use change was quantified for 10 groups within which cultural traditions and production systems are shared, including three nonmechanized indigenous groups, four mechanized farming groups, two cattle ranching groups, and the forest products sector. Mechanized Cruceño farmers and Andean indigenous colonists were responsible for most land-use change in the 1960s and 1970s; deforestation by the latter group increased to twice that by all other groups during 1986–1991, declined in the 1990s, and then increased again in the most recent period. In the last 15 years, land-use change by agro-industrialists specializing in soybean has become important, and cattle ranching based on cultivated pastures has surpassed land use by all other groups. When the rates of change increased for the three indigenous nonmechanized groups, they tended to decrease for the four nonindigenous mechanized groups, and vice versa.
A Satellite Model of Forest Flammability Steininger, Marc K.; Tabor, Karyn; Small, Jennifer ...
Environmental management (New York),
07/2013, Letnik:
52, Številka:
1
Journal Article
Recenzirano
We describe a model of forest flammability, based on daily satellite observations, for national to regional applications. The model defines forest flammability as the percent moisture content of ...fuel, in the form of litter of varying sizes on the forest floor. The model uses formulas from the US Forest Service that describe moisture exchange between fuel and the surrounding air and precipitation. The model is driven by estimates of temperature, humidity, and precipitation from the moderate resolution imaging spectrometer and tropical rainfall measuring mission multi-satellite precipitation analysis. We provide model results for the southern Amazon and northern Chaco regions. We evaluate the model in a tropical forest-to-woodland gradient in lowland Bolivia. Results from the model are significantly correlated with those from the same model driven by field climate measurements. This model can be run in a near real-time mode, can be applied to other regions, and can be a cost-effective input to national fire management programs.
The neotropical-forest's northern and southern extremes, covering the Mexican Yucatán and the Argentine Chaco, have among the highest rates of recent tree-cover loss in the biome. This study ...contrasts the character of loss in these regions, estimating proportions of types of loss and subsequent land cover. It is based on two-stage probability sampling design and field and satellite-image surveys. All estimates include uncertainties, which could be further reduced via model-assisted estimation or additional sampling. This approach can be replicated in other regions to estimate types of loss and associated land cover from a definitive, in-situ perspective. The character of loss in the two areas differed greatly. That in the Yucatán was 54% temporary, mostly under fallow or selectively logged, while that in the Chaco was 85% permanent, split nearly equally between crops and pasture. These data contribute to a quantitative basis for studies of socio-economic drivers of neotropical deforestation.
We evaluate the potential of a proposed policy model that would explicitly link the cultivation of biofuels with forest conservation (Biofuel+FC) as part of the United Nations Framework Convention on ...Climate Change. The model postulates that a ratio of 4:1 forest conservation to biofuel cultivation be linked to proposals for reducing emissions from deforestation and forest degradation (REDD+Biofuel), while a ratio of 9:1 biofuel cultivation to reforestation on degraded landscape (RDL+Biofuel) be linked to the afforestation/reforestation component of the Clean Development Mechanism. Both biofuel production options would be limited to the cultivation of woody perennial biofuel species on low biomass landscapes in order to maximize the carbon benefits of the proposed policy model. The potential to conserve forest, avoid GHG emissions, improve carbon sequestration, and produce renewable energy are evaluated by an illustrative model for five case studies (Pará – Brazil, East Kalimantan – Indonesia, Madagascar, Colombia and Liberia). The Biofuel+FC policy model is then compared with three counterfactual scenarios: REDD Alone with no biofuel cultivation; Biofuel Alone with expanded biofuel cultivation in the absence of REDD and a Most Likely scenario where REDD and biofuel cultivation are implemented without explicit regulatory linkages. The proposed policy model would leverage forest carbon with biofuel markets, which would reduce greenhouse gas emissions and conserve biodiversity, as well as improve human welfare in developing countries, a win–win–win strategy for sustainable development.
► We propose to link biofuel cultivation with forest conservation (REDD+Biofuels). ► A similar proposal to support reforestation on degraded landscapes (RDL+Biofuels). ► Woody perennial biofuel species on low biomass landscapes maximize carbon benefits. ► REDD+ revenues can subsidize and foster sustainable biofuels. ► Production of sustainable biofuels can strengthen REDD+ initiatives.
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