Deforestation Trends Research Articles

The prehistoric and preindustrial deforestation of Europe

Humans have transformed Europe's landscapes since the establishment of the first agricultural societies in the mid-Holocene. The most important anthropogenic alteration of the natural environment was the clearing of forests to establish cropland and pasture, and the exploitation of forests for fuel wood and construction materials. While the archaeological and paleoecological record documents the time history of anthropogenic deforestation at numerous individual sites, to study the effect that prehistoric and preindustrial deforestation had on continental-scale carbon and water cycles we require spatially explicit maps of changing forest cover through time. Previous attempts to map preindustrial anthropogenic land use and land cover change addressed only the recent past, or relied on simplistic extrapolations of present day land use patterns to past conditions. In this study we created a very high resolution, annually resolved time series of anthropogenic deforestation in Europe over the past three millennia by 1) digitizing and synthesizing a database of population history for Europe and surrounding areas, 2) developing a model to simulate anthropogenic deforestation based on population density that handles technological progress, and 3) applying the database and model to a gridded dataset of land suitability for agriculture and pasture to simulate spatial and temporal trends in anthropogenic deforestation. Our model results provide reasonable estimations of deforestation in Europe when compared to historical accounts. We simulate extensive European deforestation at 1000 BC, implying that past attempts to quantify anthropogenic perturbation of the Holocene carbon cycle may have greatly underestimated early human impact on the climate system.

Investigation of terminalia ( Terminalia belerica Robx.) seed oil as prospective biodiesel source for North-East India

Terminalia ( Terminalia belerica Robx.) is available in the northeastern region of India. The fruit of terminalia has some medicinal value and its kernel contains 43% oil. The prospect of terminalia oil for biodiesel production is investigated with reference to some relevant properties. The fatty acid profile of oil extracted from terminalia is found comparable with similar seed oils attempted for biodiesel production in this region. Terminalia oil contains 32.8% palmitic acid, 31.3% oleic acid, and 28.8% linoleic acid. The calorific value and kinematic viscosity of terminalia oil are 37.50 MJ/kg and 25.60 cSt, respectively. The calorific value and cetane number of terminalia FAME are within the acceptable limit of the EN 14214 standard. However, the flash point of terminalia FAME (90 °C) is relatively lower than the minimum required standard. Overall, the properties of biodiesel obtained from terminalia seed conform to the existing biodiesel standard. In addition to assisting the national biodiesel mission, the extension and regeneration of forest areas through terminalia planting would help us to curb the seemingly irreversible trend of de-forestation in the northeast region of India.

The Melting Himalayas: Cascading Effects of Climate Change on Water, Biodiversity, and Livelihoods

The Greater Himalayas hold the largest mass of ice outside polar regions and are the source of the 10 largest rivers in Asia. Rapid reduction in the volume of Himalayan glaciers due to climate change is occurring. The cascading effects of rising temperatures and loss of ice and snow in the region are affecting, for example, water availability (amounts, seasonality), biodiversity (endemic species, predator-prey relations), ecosystem boundary shifts (tree-line movements, high-elevation ecosystem changes), and global feedbacks (monsoonal shifts, loss of soil carbon). Climate change will also have environmental and social impacts that will likely increase uncertainty in water supplies and agricultural production for human populations across Asia. A common understanding of climate change needs to be developed through regional and local-scale research so that mitigation and adaptation strategies can be identified and implemented. The challenges brought about by climate change in the Greater Himalayas can only be addressed through increased regional collaboration in scientific research and policy making.

Carbon sequestration in forest trees of the EU as affected by long-term changes of land use.

Abstract The biomass of forest vegetation expands in all EU countries. This review analyses the long-term development of forest vegetation and, thereby, the sequestration of carbon in forest biomass in the EU, country by country. The sequestration estimates and their uncertainties are assessed focusing on the period 1990-2006. The most recent estimates are compared with those for earlier times. A case study from Finland is presented, which helps understand the causal mechanisms affecting long-term sequestration of carbon in forest vegetation on a centennial scale. The forests of the 27 countries of the European Union (EU-27) represent approximately 4% of global forest area and 5% of global growing stock volume [1]. Despite their relatively small global shares, the region's forests remove carbon from the atmosphere at a surprisingly high rate. During 1990 to 2006 within the 27 countries (that were members of the EU in 2008) the expanding woody biomass annually sequestered 360 to 495 million tonnes CO 2 from the atmosphere ( high confidence ). The rate of sequestration accelerated over time during the same period ( low confidence ). Over a more extended decadal scale from 1900 to 2006, the rate accelerated ( high confidence ). The biomass sink was mainly driven by increasing density of average European forests and to a lesser extent by increasing forest cover ( high confidence ). Changes in forestry, nature conservation and other land management practices were the main drivers of carbon sequestration ( medium confidence ). The contribution of carbon sequestration in forests to the national carbon budget varied among countries depending on the extent of forests. Estimates for individual years varied and the accuracy and precision of the national estimates was not high, typically ±30%. A three-year moving average can be recommended as a basis for calculations, because it evens out inter-annual variation. Biomass sequestration has potential to continue in the EU for at least 50 years into the future. If land use trends revert and consumption patterns change, for example, if the demand for agricultural and wood products increases and bioenergy is developed on a large scale, sequestration can decelerate in the very long term. Climate change in itself is a risk factor to forest ecosystems in terms of increasing risks of storm damage, forest fire, forest pests and drought. Losing the biomass sink in EU, notably only a theoretical scenario in the next 20 to 30 years, would become an obstacle to reaching the main goal of climate policy: a stable atmosphere in terms of greenhouse gases. Promoting the sink on the other hand would make a contribution to achieving that goal. If the global trends of deforestation and forest degradation are reverted, forest sequestration of carbon can make an important contribution to stabilizing the atmosphere and preventing a serious climate change. Forest biomass has a potential to expand significantly worldwide.

Highland Forest Habitat Preference by Endemic Hawai‘ian Honeycreepers: A Preliminary Assessment

This paper examines the use of degraded, “suburbanized”-type highland forests in east Hawai‘i (Hawai‘i Island) versus more pristine, protected forest found in Volcanoes National Park by two endemic honeycreeper species, the apapane ( Himatione sanguinea ) and the amakihi ( Hemignathus virens ). This research is important because east Hawai‘i is experiencing rapid and extensive forest clearance due to a boom in home construction that began five years ago and continues today. This forest clearance not only destroys or degrades forest ecosystems, but it also leads to the introduction of exotic, usually ornamental plant species where few existed previously. The habitat fragmentation that has resulted also appears to be creating edge/fragmented environments in which alien bird species thrive. If current development and deforestation trends continue, further increasing the impact of edge/fragmentation-related effects, breeding populations of the remaining once-common honeycreepers may be relegated to the few large protected areas in Hawai‘i such as Volcanoes National Park and other fragmented forest islands. If this occurs, these species will be much more susceptible to catastrophic population declines. It is critical, therefore, that public officials work to protect remaining stands of native forest through new zoning laws that recognize the importance and uniqueness of east Hawai‘i’s native forests and their wildlife inhabitants.

Temporal mapping of deforestation and forest degradation in Nepal: Applications to forest conservation

Deforestation and forest degradation are associated and progressive processes resulting in the conversion of forest area into a mosaic of mature forest fragments, pasture, and degraded habitat. Monitoring of forest landscape spatial structures has been recommended to detect degenerative trends in forest conditions. GIS and remote sensing play an important role in the generation of such data to identify degraded and deforested areas as well as potential areas for conservation. In this study we analyzed forest degradation and deforestation trends in Chitwan district in Nepal, which contains key habitat elements for wildlife in the region. An artificial neural network was used to predict forest canopy density in five classes using Landsat images of the year 2001. Forest canopy density was predicted with 82% overall accuracy. Except riverine forest, forest area of all other forest types was reduced. Terai Shorea robusta forest, which has high commercial value, showed a loss of 23% between 1976 and 1989 and an overall loss of 15% forest covers between the year 1976 and 2001. Deforestation and forest degradation disproportionately reduced the sizes of the different forest types, a finding that has important management implications. The maps presented in this article could be useful to prioritize limited resources for conservation.

Forest fragmentation and regrowth in an institutional mosaic of community, government and private ownership in Nepal

This study analyzes forest change in an area of Nepal that signifies a delicate balance between sustaining the needs and livelihood of a sizable human population dependent on forest products, and an effort to protect important wildlife and other natural resources. The study area, a portion of the Chitwan valley district of Nepal, represents what may be becoming a common institutional mosaic in many countries of the world who have a population reliant on forest products for their livelihood: (1) a national park; (2) a designated park buffer involving participatory forest management programs; (3) scattered patches of designated community forest; and (4) large areas of adjacent landscape made up of mostly private landholdings under agricultural practices. Utilizing Landsat images from 1989 and 2000, we analyze land cover change in each of these management zones using landscape ecology metrics and quantifying proportional distributions of land cover categories. Our results show significant differences in terms of land cover dynamics and landscape spatial pattern between these land ownership classes. These findings indicate that community-based institutions (participatory management programs in the park buffer and the designated community forests) are capable of halting or even reversing trends in deforestation and forest fragmentation.

Land use dynamics and landscape history in La Montaña, Campeche, Mexico

Current status and trends of deforestation are assessed for the region of La Montaña, Campeche, Mexico, a buffer zone for the Calakmul Biosphere Reserve, by interpreting remotely sensed satellite image data. A change detection analysis of three satellite images was used to assess forest clearing for agriculture from two time periods (1988–2000 and 2000–2005). Buffers from specific variables (distance to roads, distance to settlements and proximity to lowland flooded forest) were used to assess deforestation patterns and identify potential variables that determine land use change. Results show annual deforestation rates increase from 0.3% between 1988 and 2000 to 0.7% between 2000 and 2005, which indicate that forest conversion is intensifying. Deforestation appears to be prominent near lowland flooded forests on soil types identified by local people as suitable for agriculture, particularly for pasture establishment. Recent occurrence of deforestation in the area is strongly associated with soil/vegetation characteristics, infrastructure development and settlement locations while the proximate causes are related to agricultural expansion. Although the economy in the region is still greatly dependent on traditional forest management, in the last decade cattle ranching has been institutionally promoted and is an economic alternative that has been increasing in importance.

An operational deforestation mapping system using MODIS data and spatial context analysis

The Brazilian Amazon has the world's highest absolute rate of forest loss, currently averaging nearly 2 million hectares per year. In this study, we present a near‐real‐time automated deforestation mapping system for the Brazilian Amazon based on the analysis of spatial context information and MODIS Vegetation Index products and implemented on an ArcGIS 9.0 platform. This system, already validated and operational, was developed as part of the “Integrated Warning Deforestation System for the Amazon” (SIAD), an initiative of the Brazilian government within the scope of the Amazon Protection System (SIPAM), which also comprises: (1) a spatial information module, aimed at the assessment of the causes and impacts of the deforested areas; (2) a prediction module, indicative of deforestation trends; and (3) a data and information gateway based on map server technology.

Spatial and temporal analysis of vegetation change in agricultural landscapes: A case study of two brigalow (Acacia harpophylla) landscapes in Queensland, Australia

The majority of landscapes around the world have been modified or transformed by human activities to meet the needs of human societies. The loss of native vegetation for agricultural development affects the sustainability of growing proportion of the world's ecosystems. Factors such as land tenure, roads and agricultural intensification, together with biophysical properties, have been cited as drivers of deforestation. This paper combined analysis of the historical drivers of change with analysis of the trends of deforestation since 1945 in two brigalow landscapes (100,000 ha) in sub-tropical Australia. A selection of these drivers were then applied at a property-level (1000 ha) to test their influence on native vegetation retention. Regression trees were used to identify significant human drivers and biophysical properties, and then a generalised linear modelling approach was used to quantify the effect of these factors on the proportion of remnant native vegetation. Results showed that until the mid-20th century, government policies to intensify settlement did not result in increased agricultural production, but since this time, landscape change has been rapid, and has particularly affected ecosystems on fertile clay soils. Although socio-economic factors were critical in driving deforestation, after 60 years of agricultural intensification by far the most significant explanatory variable determining the proportion of native vegetation retained at a property scale was the suitability of the soil for agriculture. Property size was an important secondary influence. The results were not, by and large, consistent with other studies of landscape change and suggest that generalised principles explaining deforestation may be elusive. Solutions to the problem of over-clearance of native vegetation, therefore, need to be tailored to the specific regional situations encountered.

Forest Conversion and Land Use Change in Rural Northwest Yunnan, China

Contrary to the trend of rapid deforestation continuing across Asia, regional assessments point to recent increases in forest cover in China, including Yunnan Province, since the implementation of dramatic forestry policy changes. There is debate about whether the statistics that describe increasing forest cover adequately account for forest status and quality. In this context, the present article aims to quantify forest cover and land use changes in a Tibetan-dominated rural township in northwest Yunnan, China—an ecologically important region affected by recent forest policy changes. Three sequences of Landsat satellite imagery dating from 1981 to late 1999 and other digital datasets were used in a rules-based hybrid classification approach, achieving acceptable accuracy assessment scores.The results show an average aggregate decline in conifer forests of 23%, mostly due to an active logging industry. Much of this forest has converted to shrubland, which increased in area by over 100%. Grassland also increased, mainly at the expense of cultivation, as a response to increasing dependence on livestock by the rural communities, although high elevation rangelands decreased in area due to changing livelihoods and restrictions by the government on grazing and deliberate burning. Using the accepted definitions of forest and shrub-land categories, it was difficult to depict forest and shrub-land dynamics due to variation in forest regeneration and afforestation, dieback-affected forests, secondary succession of disused rangelands, and a variety of other mixed community types. Conversion analysis revealed significant forest–shrubland exchanges occurring even during the 1990s when reduction in overall forest cover slowed considerably. The results support the view that the standard categorizations and representations of land cover only portray a partial picture of forest status, as they do not account for multiple conversions that occur between different land covers over time. Due to ongoing forestry programs and increasing utilization of forest resources by local communities, these conversion issues may be significant, with implications for forest quality and biodiversity.Our understanding of China's forest status will be improved by correlating inventory data with finer-scale spatial datasets to enable conversion analysis in representative ecological regions. This will advance our knowledge of China's forest status and the effectiveness of forest policy for both local rural community needs, as well as for broader ecological conservation.

Trends in land cover change and isolation of protected areas at the interface of the southern boreal mixedwood and aspen parkland in Alberta, Canada

The Beaver Hills region of central Alberta is located at the interface of the southern boreal mixedwood forest and the aspen parkland, an area now dominated by agriculture, urban and industrial development. Increasing anthropogenic land cover will eventually isolate remaining natural habitats currently protected in parks and reserves. This paper analyzes land cover and land cover change (LCC) in the Beaver Hills moraine and surrounding areas using a structured hierarchical satellite imagery classification applied to Landsat Multi Spectral Scanner and Thematic Mapper from 1977, 1987, and 1998. Our goal was to quantify deforestation and habitat fragmentation trends and then discuss how this information could be used to develop a conservation approach that will protect current areas against further habitat loss. We found that the rate of deforestation in the lands surrounding the moraine was similar to the broad trend at the southern periphery of the Canadian boreal forest region: annual rate of change in forest cover was −0.82%/year. However, in the Beaver Hills there was a net gain of +0.61%/year, due to regeneration of low quality agricultural lands. All fragmentation indices used indicated an increase in forest fragmentation. We designed a network of protected areas and remaining large forest patches, based on the UNESCO-MAB biosphere model. Our results underline concerns regarding the increasing isolation of national parks and biological reserves in Canada.

Unreported yet massive deforestation driving loss of endemic biodiversity in Indian Himalaya

Deforestation is a primary driver of biotic extinctions in the tropics. The impacts of deforestation in tropical biodiversity hotspots are of particular concern because these regions contain high concentrations of globally endemic species. However, the effects of large-scale deforestation on native biotas within the biodiversity hotspot of Himalaya remain poorly documented. Here we report on an alarming trend of deforestation in the Indian Himalaya and project the likely consequential extinctions of endemic taxa (species and subspecies) by 2100 across a broad range of taxonomic groups, including gymnosperms, angiosperms, fishes, amphibians, reptiles, birds, and mammals. With the current level of deforestation, by 2100 only about 10% of the land area of the Indian Himalaya will be covered by dense forest (>40% canopy cover)—a scenario in which almost a quarter of the endemic species could be wiped out, including 366 endemic vascular plant taxa and 35 endemic vertebrate taxa. We also show that inaccurate reporting of forest cover data by governmental institutions can result in underestimations of the biological impacts of deforestation, as well as potential miscalculations in land-use decisions (e.g., the construction of hydroelectric dams). Large-scale conservation efforts, including forest protection and reforestation, are urgently needed to avoid the impending deforestation-driven biodiversity losses in the Himalaya.

Deforestation in a Complex Landscape

Deforestation is often the primary threat to conservation goals in tropical countries. However, accessing the remote locations in which most remaining forests of conservation value occur makes it difficult to quantify deforestation trends and to galvanize preventive action. Using remotely sensed images we were able to quantify rates of forest loss in La Amistad Biosphere Reserve, Panama. Annual deforestation rates were low between 1987 and 1998 at 0.05% but increased nearly 12-fold between 1998 and 2001 to 0.6%. Net forest loss was 0.56% between 1987 and 1998 and 2.34% between 1998 and 2001. Deforestation rates differed significantly between protected areas. Protected areas on the Caribbean side of the Biosphere Reserve experienced greater levels of deforestation than those on the Pacific, even though both absolute and percent forest cover are higher on the Caribbean. Most forest conversion was for cattle pasture and an area of industrial cattle ranching was identified within the Palo Seco and PILA protected areas as a priority for enforcement activities. Forest conversion to pasture was highly correlated with proximity to roads, rivers, and villages (p < 0.001). The spatial scale of correlation varied between feature types, suggesting a greater area of impact from roads and towns versus rivers. The acceleration of forest conversion from 1998 to 2001 confirms the negative ecological impact of the recent increase in population and development pressure in this previously isolated region.

Cattle, crops and clearing: Regional drivers of landscape change in the Brigalow Belt, Queensland, Australia, 1840–2004

Landscape change occurs through the interaction of a multitude of natural and human driving forces at a range of organisational levels, with humans playing an increasingly dominant role in many regions of the world. Building on the current knowledge of the underlying drivers of landscape change, a conceptual framework of regional landscape change was developed which integrated population, economic and cultural values, policy and science/technology. Using the Southern Brigalow Belt biogeographic region of Queensland as a case study, the role of natural and human drivers in landscape change was investigated in four phases of settlement since 1840. The Brigalow Belt has experienced comparable rates of vegetation clearance over the past 50 years to areas of tropical deforestation. Economic factors were important during all phases of development, but the five regional drivers often acted in synergy. Environmental constraints played a significant role in slowing rates of change. Temporal trends of deforestation followed a sigmoidal curve, with initial slow change accelerating though the middle phases then slowing in recent times. Future landscape management needs to take account of the influence of all the components of the conceptual framework, at a range of organisational levels, if more ecologically sustainable outcomes are to be achieved.

Natural recharge to sustainable yield from the Barind aquifer: a tool in preparing effective management plan of groundwater resources

This paper presents the results of water balance study and aquifer simulation modeling for preliminary estimation of the recharge rate and sustainable yield for the semi arid Barind Tract region of Bangladesh. The outcomes of the study are likely to be useful for planning purposes. It is found from detailed water balance study for the area that natural recharge rates in the Barind Tract vary widely year to year. It may have resulted from the method used for the calculation. If the considered time interval had been smaller than the monthly rainfall, the results could have been different. Aquifer Simulation Modeling (ASM) for the Barind aquifer is used to estimate long-term sustainable yield of the groundwater considering limiting drawdown from the standpoint of economic pumping cost. In managing a groundwater basin efficiently and effectively, evaluation of the maximum annual groundwater yield of the basin that can be withdrawn and used without producing any undesirable effect is one of the most important issues. In investigating such recharge rate, introduction of certain terms such as sustainable yield and safe yield has been accompanied. Development of this area involves proper utilization of this vast land, which is possible only through ensured irrigation for agriculture. The Government of Bangladesh has a plan to develop irrigation facilities by optimum utilization of available ground and surface water. It is believed that the groundwater table is lowering rapidly and the whole region is in an acute state of deforestation. Indiscriminate groundwater development may accelerate deforestation trend. In this context estimation of actual natural recharge rate to the aquifer and determination of sustainable yield will assist in proper management and planning of environmentally viable abstraction schemes. It is revealed from the study that the sustainable yield of ground water (204 mm/y) is somewhat higher than the long-term annual average recharge (152.7 mm) to the groundwater reservoir. The reason behind this is that the rivers within and around the Barind Tract might have played the role of influent rivers.

Rapid Assessment of Annual Deforestation in the Brazilian Amazon Using MODIS Data

Abstract The Brazilian government annually assesses the extent of deforestation in the Legal Amazon for a variety of scientific and policy applications. Currently, the assessment requires the processing and storing of large volumes of Landsat satellite data. The potential for efficient, accurate, and less data-intensive assessment of annual deforestation using data from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) at 250-m resolution is evaluated. Landsat-derived deforestation estimates are compared to MODIS-derived estimates for six Landsat scenes with five change-detection algorithms and a variety of input data—Surface Reflectance (MOD09), Vegetation Indices (MOD13), fraction images derived from a linear mixing model, Vegetation Cover Conversion (MOD44A), and percent tree cover from the Vegetation Continuous Fields (MOD44B) product. Several algorithms generated consistently low commission errors (positive predictive value near 90%) and identified more than 80% of deforestation polygons larger than 3 ha. All methods accurately identified polygons larger than 20 ha. However, no method consistently detected a high percent of Landsat-derived deforestation area across all six scenes. Field validation in central Mato Grosso confirmed that all MODIS-derived deforestation clusters larger than three 250-m pixels were true deforestation. Application of this field-validated method to the state of Mato Grosso for 2001–04 highlighted a change in deforestation dynamics; the number of large clusters (&amp;gt;10 MODIS pixels) that were detected doubled, from 750 between August 2001 and August 2002 to over 1500 between August 2003 and August 2004. These analyses demonstrate that MODIS data are appropriate for rapid identification of the location of deforestation areas and trends in deforestation dynamics with greatly reduced storage and processing requirements compared to Landsat-derived assessments. However, the MODIS-based analyses evaluated in this study are not a replacement for high-resolution analyses that estimate the total area of deforestation and identify small clearings.

DEFORESTATION IN NORTHEAST THAILAND, 1975-91: RESULTS OF A GENERAL STATISTICAL MODEL

Using a general statistical model, this study attempts to characterise the trend of deforestation in the northeast region (Isan) of Thailand between 1975 and 1991, a period when the kingdom had sustained high rates of economic growth and steady increases in population. Using data obtained directly from government bodies on the 17 provinces comprising this heavily deforested region, the study examines the correlations between forest area and a set of six variables: population density, agricultural area, real per capita income, accumulated irrigated area, agricultural credit levels, and distance from Bangkok, the national political and economic centre. It also considers the effect of the two logging bans instituted in 1979 and since 1989. The study found a negative correlation between forest area and population density in particular, followed in ranking by agricultural credit, per capita income, the logging bans and distance from Bangkok. Viewed together with more recent data showing that rates of deforestation in the kingdom as a whole have slowed and appear to be stabilising, these results also suggest the beginnings in the 1990s of a forest transition – from an industrial to a post-industrial stage in forest utilisation – in Thailand.

Reply to Niesten and Rice’s Comment

The prescriptions advanced by ecologists and foresters about how best to preserve and/or sustainably manage tropical forest ecosystems influence public policy to varying degrees, depending on the relative power wielded by either group in international or governmental bodies at any particular moment in time. Public policy in turn is influenced by direct lobbying and through reaction to public opinion which is shaped by the debates that are presented in specialist publications like this one, the media, and in boardrooms, classrooms and conferences. Both disciplines are dominated by Northern scientists who arguably bring their own experiential biases to bear on the debates. The Commentary on Sustainable Forest Management and Conservation Incentive Agreements by Niesten and Rice is a restatement of their positions, as set out in the articles cited in their References. The Commentary first sets out the case against SFM, then moves to a promotion of conservation incentive agreements (CIA), and finally examines the case for combining the two, i.e. logging a stand of all its commercially valuable timber species and then closing it off under a conservation incentive agreement. The stated premise in the piece is the urgent need to cordon off ever larger amounts of ‘undisturbed natural habitat’ for biodiversity conservation against the continuing trend of deforestation due to logging and land clearing. The rallying cry of all these pieces is indeed to protect against disturbance of what are portrayed as the remaining ‘old growth’ tropical frontier forests. I shall comment briefly on four issues considered in this piece by Niesten and Rice: the unstated espousal of an equilibrium state for tropical forests; the critique of Sustainable Forest Management (SFM); the ‘log-andprotect’ prescription; and conservation incentive agreements. Finally I shall summarise an alternative approach to managing tropical forests sustainably, the goal desired by a planetary majority, including ecologists and foresters. My own bias is shaped by Guyanese citizenship and anthropological training. My approach, then, is that of a non-specialist, being neither ecologist nor forester. The Western science of ecology is a comparatively new field, but one whose pronouncements on the big questions of our time, from assigning responsibility among nations for global warming and climate change to species extinction rates are generally accorded great weight by public and policy makers alike. However, a number of the pronouncements of its adherents have been questioned from both inside (Botkin 1990, Wu and Loucks 1995) and outside (Blaikie 1985, Cronon 1996, Forsyth 2003) of the discipline. The underlying premise of this piece by Niesten and Rice is the undesirability of ‘disturbance’ of tropical forest ecosystems, echoing ‘the cult of wilderness’ approach of Northern ‘deep’ or Green ecologists. The goal of ‘undisturbed natural habitat,’ is introduced in paragraph 3, and recurs throughout the Commentary. The authors maintain that ‘relative to an unlogged forest, even the most careful timber harvest implies a significant disturbance that can result in a variety of negative impacts on biodiversity’. However, many ecologists and other scientists now question the equilibrium thesis, as new scientific evidence emerges of planetary disturbances and more studies published of anthropogenic forests and landscapes. Some years ago, the geographers Karl Zimmerer and

The impact of changes in agricultural technology on long-term trends in deforestation

To overcome the limitations of existing aggregated national deforestation models in explaining the impact of changes in agricultural technological on deforestation a two-zone national political economy model is outlined and illustrated by examples from the Philippines and Thailand. It suggests that deforestation trends depend on where and when new technologies are adopted and by whom. In particular, they are sensitive to the balance between adoption in the highly productive Core and the less fertile Periphery where remaining forest concentrates as a country develops. Without parallel adoption in the Periphery, rising yields in the Core alone may not control deforestation. State intervention can help to overcome adoption bias but is still limited by state–élite–corporate links. Five criteria are proposed to assess the likely effectiveness of agricultural policies to control deforestation: (1) improve sustainable farm productivity in the Core, (2) improve sustainable farm productivity in the Periphery, (3) generate sufficient manufacturing/service jobs for ex-farmers, (4) reform land tenure and (5) decentralize state agriculture departments to promote the participation of farmers in the design of appropriate technologies. Deforestation is likely to continue if criteria 1–3 are not met.