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1.
Roads and topography can determine patterns of land use and distribution of forest cover, particularly in tropical regions. We evaluated how road density, land use, and topography affected forest fragmentation, deforestation and forest regrowth in a Brazilian Atlantic Forest region near the city of São Paulo. We mapped roads and land use/land cover for three years (1962, 1981 and 2000) from historical aerial photographs, and summarized the distribution of roads, land use/land cover and topography within a grid of 94 non-overlapping 100 ha squares. We used generalized least squares regression models for data analysis. Our models showed that forest fragmentation and deforestation depended on topography, land use and road density, whereas forest regrowth depended primarily on land use. However, the relationships between these variables and forest dynamics changed in the two studied periods; land use and slope were the strongest predictors from 1962 to 1981, and past (1962) road density and land use were the strongest predictors for the following period (1981–2000). Roads had the strongest relationship with deforestation and forest fragmentation when the expansions of agriculture and buildings were limited to already deforested areas, and when there was a rapid expansion of development, under influence of São Paulo city. Furthermore, the past (1962) road network was more important than the recent road network (1981) when explaining forest dynamics between 1981 and 2000, suggesting a long-term effect of roads. Roads are permanent scars on the landscape and facilitate deforestation and forest fragmentation due to increased accessibility and land valorization, which control land-use and land-cover dynamics. Topography directly affected deforestation, agriculture and road expansion, mainly between 1962 and 1981. Forest are thus in peril where there are more roads, and long-term conservation strategies should consider ways to mitigate roads as permanent landscape features and drivers facilitators of deforestation and forest fragmentation.  相似文献   

2.
3.
Scholars, policy-makers and advocates have, in the last decade, recommended greater involvement by non-governmental organizations (NGOs) in community forest management in developing countries. Behind these recommendations lies a notion that NGOs are a sound complement to formal governments and that NGOs can improve communities’ abilities to manage their own forests. There is limited empirical work, however, testing how NGO activity affects local forest governance and deforestation. This paper reports the results of quantitative statistical tests on the effects of local NGO importance—as measured by local forest users’ reports of NGO importance—on deforestation in a sample of 200 rural Bolivian communities. In addition, it examines the effect of NGO importance on community forestry institutions—specifically, the presence of institutions for rule-making, forest monitoring, sanctioning, and enforcement of rules. Contrary to earlier research, these results suggest that NGOs have no discernible effect on community forestry institutions, though other external actors—most notably, municipal governments—seem to have a positive effect. The paper also reports a negative correlation of NGO importance on deforestation. Although these quantitative results are in part supported by qualitative field observations in selected Bolivian communities, care is needed in drawing generalized causal inferences from this evidence.  相似文献   

4.
Central Rondônia is one of the most deforested regions in the Brazilian Amazon and contains areas at different stages of degradation forming a gradient from mature forest to highly urbanized and built-up areas. Regional data from satellite imagery are available from the 1980s, but apart from studies that quantify deforestation, the broad-scale landscape dynamics of Rondônia have not been examined well. This paper assesses the landscape changes between 1984 and 2002 in a watershed located in the central region of the state of Rondônia, Brazil, which has undergone systematic and rapid deforestation due to introduction of pasture that began in the 1970s. Bi-annual Landsat TM/ETM+ images from 1984 to 2002 were classified into three broad land cover types: mature forest, secondary forest, and pasture, resulting in a time series of land-use/land-cover maps. Landscape changes were evaluated by computing a cross tabulation between years, transition rates, and landscape metrics related to size, density, connectivity, configuration, and deforested patches distribution related to patch size and spatial proximity to roads and old pastures. Transition probability functions were fitted to the temporal series to predict land-use changes for the next 10 years, for three different scenarios: (1) continued land-use change; (2) eliminating clear-cutting and selective logging; and (3) eliminating clear-cutting, selective logging, and secondary vegetation clearing. Current land-use transitions cannot be sustained beyond the next 10–15 years. A more sustainable scenario for the region requires a major reduction of deforestation activities, implementing the “permanent preservation area” policy along riversides, and controlling land-use transitions at balanced levels. We recommend that forest managers in regions facing similar deforestation pressures should strive to maintain at least 35% mature or primary forest, because landscape fragmentation proceeds rapidly below this critical threshold.  相似文献   

5.
Soil fauna can sensitively respond to alterations in soil environment induced by land-use changes.However,little is known about the impact of urban land-use changes on earthworm communities.In this study,three land-use types(i.e.,forest,nursery and abandoned lands)were chosen to identify differences in diversity,abundance and biomass of earthworm community in Kunming City.Urban land-use had a pronounced difference in species composition,evenness and diversity of earthworm communities.Forest land had the highest density,biomass and diversity of the earthworm communities.Total abundance was dominated by endogeic species in nursery land(70%)and abandoned land(80%),whereas in the forest land,the earthworm community comprised epigeic,endogeic and anecic species.Temporal changes in earthworm density and biomass were also significantly affected by land-use change.Total density and biomass of earthworms in the forest and nursery lands were highest in September,but highest in the abandoned land in October.The influence of soil physicochemical properties on the earthworm density and biomass also varied with land-use types.Soil temperature significantly affected earthworm density and biomass in the three land-use types.Soil pH was positively correlated with earthworm biomass in the forest land,but negatively associated with earthworm density in the abandoned land.Soil organic matter was positively correlated only with density and biomass of earthworms in the nursery and abandoned lands.Our results suggest that the species composition,abundance and biomass of earthworm communities can be determined by the modification of soil properties associated with urban land-use type.  相似文献   

6.
  • ? The Government of Papua New Guinea (PNG) has played a prominent part in recent negotiations for “rainforest nations” to be compensated for reducing greenhouse gas emissions from deforestation or forest degradation (DFD).
  • ? A new report “The State of the Forests of Papua New Guinea” claims that rates of DFD in PNG are much higher than have previously reported. It suggests more than half of PNG’s remaining forests will have disappeared or be damaged beyond recovery by 2021.
  • ? We argue that this claim is incorrect. The report overestimates the area of intact primary forest in 1972 and the impact of traditional land use practices on forest cover. Much of what the RSLUP report considers as deforestation is part of a cycle of traditional clearance for farming, fallow and regrowth that has been occurring for hundreds of years.
  • ? The assumption that areas impacted by harvesting or shifting cultivation will inevitably degrade and become non-forest is also not supported by observation of cutover forest in PNG. A considerable proportion of cutover forest areas will recover carbon stocks after harvesting.
  • ? It is argued that traditional land use practices and forest recovery processes need to be considered in assessing greenhouse gas emissions from deforestation and degradation in countries with complex land use histories such as PNG.
  •   相似文献   

    7.
    In Rondônia State, Brazil, settlement processes have cleared 68,000 km2 of tropical forests since the 1970s. The intensity of deforestation has differed by region depending on driving factors like roads and economic activities. Different histories of land-use activities and rates of change have resulted in mosaics of forest patches embedded in an agricultural matrix. Yet, most assessments of deforestation and its effects on vegetation, soil and water typically focus on landscape patterns of current conditions, yet historical deforestation dynamics can influence current conditions strongly. Here, we develop and describe the use of four land-use dynamic indicators to capture historical land-use changes of catchments and to measure the rate of deforestation (annual deforestation rate), forest regeneration level (secondary forest mean proportion), time since disturbance (mean time since deforestation) and deforestation profile (deforestation profile curvature). We used the proposed indices to analyze a watershed located in central Rondônia. Landsat TM and ETM+ images were used to produce historical land-use maps of the last 18 years, each even year from 1984 to 2002 for 20 catchments. We found that the land-use dynamics indicators are able to distinguish catchments with different land-use change profiles. Four categories of historical land-use were identified: old and dominant pasture cover on small properties, recent deforestation and dominance of secondary growth, old extensive pastures and large forest remnants and, recent deforestation, pasture and large forest remnants. Knowing historical deforestation processes is important to develop appropriate conservation strategies and define priorities and actions for conserving forests currently under deforestation.  相似文献   

    8.
    Policies play a vital role in setting priorities and actions for forest use and management. High rates of forest loss can be attributed to failure by policies to reduce deforestation and forest degradation. It is argued that in most Least Developed Countries such as Zambia, adopted forest and natural resources policies are rarely put into effect resulting in ecosystem degradation.This study examined policy actor's perception of implementation of policies aimed at reducing deforestation and forest degradation and their implications for forest resources.To examine policy implementation, 55 policy actors were interviewed at national, regional and local levels. This included government officials, Non-Governmental Organisations, traditional leaders and local people. Interviews were analysed using discourse analysis.Findings show that policy implementations deficits are prevalent in Zambia's forest sector. Policy actors identified the main barriers as inadequate institutional capacity, inadequate legal framework, political influences, insecure land tenure, poor funding, and lack of intersectoral coordination. The paper has shown gaps between policies and their implementation. To halt deforestation and forest degradation, it is imperative that formulated policies are implemented. This will require improved communication and coordination among government units and various stakeholders, sufficient resources and harmonizing policies and legal frameworks.  相似文献   

    9.
    Summary

    Over the past decades, Central America has suffered some of the highest deforestation rates worldwide. Vast tracts of forest have been converted to agriculture and pasture, encouraged by ill-designed government policies and perverse incentives. Recently, however, progress has been made toward more sustainable use of forest resources by adjusting forest policies, decentralizing forest administration, and providing conducive incentives through environmental service payments and forest certification. Valuable forest management experiences have been gained by indigenous and peasant communities. Community forestry in Central America is being increasingly recognized by national governments. Examples include the community concessions in Peten, Guatemala, and community-based forest operations in Honduras and Nicaragua. Stakeholder networks have been established that strengthen horizontal and vertical alliances among wood producers and manufacturers and that help promote both community development and forest conservation. However, illegal logging, poor law enforcement, and lack of economic viability of forest management involving nontraditional species still provide barriers to the sustainable management of tropical broadleaved forests in the region. Future challenges include improved governance through decentralized forest administration, private sector involvement, and third-party certification. To improve traceability and value adding, development of integrated supply chains of forest and wood products is recommended.  相似文献   

    10.
    Many studies have stressed the importance of trees to rural households. Few, however, have focused on actual numbers and densities of trees in different land-use systems. Based on community-level participatory research in six communities, semi-structured household interviews and full-farm fruit tree inventories, this study aims to understand farmers’ tree-planting strategies. Relationships between the diversity, number and density of fruit trees and farm size, land-use system, land tenure, distance from the homestead, proximity to the forest, market access and household characteristics are investigated. The key factors determining the differences in tree-growing strategies between communities appear to be market access, land use and access to forest resources. Within communities, differences between individual households were less easy to explain but tenure was important as was farm size. Smaller farms had higher fruit tree densities, a relationship that was particularly strong in communities with good market access. Overall there was a great deal of variability both within and between communities and many of the factors affecting tree-planting decisions were found to be highly inter-related. Despite this complexity, trees on farm play an important role in rural household's livelihoods. Therefore, expansion of tree cultivation should be recognized as a promising pathway to achieve increased income and food production by policy makers and extensionists alike. In addition to improved tree propagation and management techniques, farmers should be strengthened in the processing and marketing of agroforestry tree products and more emphasis should be placed on the development of tree enterprises. By doing so, farmers will be able to earn a more important and consistent income from fruit trees, contributing to the Millennium Development Goals.  相似文献   

    11.
    Miombo woodlands are the most extensive natural forest type in subtropical Africa, supporting the livelihood of over 100 million urban and rural settlers. These forests continue to experience extensive deforestation and land degradation due to land use land cover (LULC) changes. The aim of this study is to use remotely sensed images from the Landsat archive to provide the baseline for the spatial extent of Miombo woodlands in Luanshya district of the Copperbelt Province, Zambia. It also assesses the implications of spatial-temporal changes for the conservation of these woodlands. A hybrid classification method involving ISODATA and Support Vector Machine classifiers was used to generate LULC maps for 1986, 1998, 2001, 2004, 2011 and 2016, with an overall accuracy of 82.0%–99.6% and kappa coefficient of 0.80–0.99. Unlike previous studies that have mainly focused on comparison between two or three time periods, a longitudinal analysis over the 20-year periods of this study shows that there are complex net and gross changes in different LULC types over different scales. Landscape change metrics indicate that woodlands have been declining in extent, but are partly offset by regeneration. Rates of deforestation (regeneration) for the periods 1986–1998, 1998–2001, 2001–2004, 2004–2011 and 2011–2016 are 10% (1%), 38% (30%), 15% (7%), 11% (8%) and 9% (2%) per annum, respectively. These results suggest that over 68% of Miombo woodlands present in 2016 are second-growth forests. Restoration strategies such as assisted natural regeneration are necessary in order to accelerate the recovery of natural forests. Targeting under-used and degraded land for assisted natural regeneration and empowering local communities in sustainable environmental stewardship are crucial in remediating against continued forest degradation.  相似文献   

    12.
    Increasing population in the forest zone of Cameroon has led to reduction of fallow periods and to diminution of per capita cropping land area. Alley farming is a promising technology for the zone; however, its large scale adoption depends on host of factors of which an important one is tree and land tenure. For this reason, a study was conducted in 1990 to determine implication of national land legislation and customary land and tree tenure on the adoption of alley farming in the forest zone of Cameroon.Despite national laws purposing to regulate land and tree use, ownership rights to land and trees are largely determined by customary tenure rules. According to the forest zone customs, land is passed on from father to son when the father dies. Owners of inherited lands have full rights on lands and these rights are rarely revoked. Women do not own lands but are allowed to crop any piece of their husband's land as long as they stay married. Despite the lack of land ownership, women might still readily adopt alley farming because they are primarily concerned about food crop production and the amount of land to be given to their sons in the future.Study funded by the International Livestock Center for Africa (ILCA), Addis-Abeba, Ethiopia, and technically supervised by the Land Tenure Center (LTC), University of Wisconsin, Wisconsin USA.  相似文献   

    13.
    In the Brazilian Amazon, insecure property rights are among the main causes of land conflicts and deforestation. Through an in-depth empirical case study in Maranhao in the Eastern Amazon, this research analyzes how distorted agrarian, forest and environmental policies, laws and regulations originated insecure property rights not only over land, but also over timber, which allied to social and political factors, such as uneven distribution of land and strong organization of landless peasants, led to land conflicts and deforestation. This paper also shows that the causes of and the several actors involved in the deforestation of the Amazon were not independent, rather they were related and interact to each other. Compatibility between environmental goals and agrarian policies, regulations and laws are necessary to provide secure and clear property rights to allow a better enforcement of environmental regulations and to give actors incentives to avoid deforestation.  相似文献   

    14.
    Oil palm plantations have been touted as one of the main drivers of deforestation in Indonesia. This paper aims to explain how oil palm companies accumulate power that enables them to control forestland and convert it into oil palm. Specifically, this paper identifies empirical evidence pointing to why oil palm companies emerge as powerful actors in land use conflicts. This paper uses the case of forest lands claimed by different actors – i.e. a timber plantation company, an oil palm company, and local communities – in West Kalimantan, Indonesia. Before the decentralisation policy, the interests of timber plantations were principally safeguarded by coercion from the forest ministry. The timber company was also supported by local communities by promising financial incentives to them. Following the decentralisation policy, additional actors get involved in the land use conflicts leading to more complex power interplays. In fact, some forestlands licensed for timber plantations are used by the oil palm company. Oil palm interests resonate with the economic interests of local governments, who use their legal mandates on land use allocation to facilitate the establishment of oil palm. The power of the oil palm company is also enhanced by the support from local communities, to which it handed more financial incentives than those of the timber plantation. It also used dominant information of customary claims and land appropriation by the ministry of forestry, with which it persuades local communities to pressurize government institutions to support oil palm operations.  相似文献   

    15.
    In this paper, we investigate the interactions and feedbacks between the drivers of forest cover and other land uses by building a novel longitudinal dataset and adopting alternative modeling strategies. Our longitudinal dataset integrates land-use and land-cover change (LULCC) information, derived by interpreting satellite imagery, with social-economic statistics across eight counties in Heilongjiang over a period of 37 years. Employing both instrument variable and system of equations methods, our models capture the inherent endogeneity embedded in the land-use changes and the effects of such factors as demographic change, economic development, and management transition on the forest condition. To validate the robustness of our models, a series of identification, endogeneity, and other tests are conducted. Our results demonstrate the dominant role of agricultural expansion in forestland loss as well as the importance of considering the substitution between forestland and wetland in analyzing the drivers of LULCC in general and deforestation in particular. The significant coefficient of the Natural Forest Protection Program implies that it has played a positive role in protecting local forests. The positive coefficient of built-up area in the farmland equation suggests a strong link between farming and residential/commercial construction; likewise, the negative coefficient of irrigation indicates that wetland loss is adversely affected by the change in local cropping pattern. It is hoped that these and other findings will improve our knowledge of the forest dynamics and their socioecological drivers, leading to more effective policy making and implementation and, ultimately, better resource conditions.  相似文献   

    16.
    Shifting slash-and-burn agriculture is likely one of the main causes of forest degradation in southern Belize. Although many development projects have attempted to reduce the impacts of agriculture on the tropical rainforest, the situation is still a cause for concern. A study of the farming system of the San Jose Maya community was therefore carried out to examine agricultural production in its social, cultural, economic, and political context. Results demonstrate that agricultural production contributes to forest degradation because of the limited availability of agricultural land, the low level of investment in agricultural production, the land tenure system, limited marketing opportunities, and the exclusion of Mayas from the country's political and economic domains. Agroforestry could, however, offer a partial solution to the problem of forest degradation. Three types of traditional agroforestry systems are practised in San Jose: the milpa (a slash-and-burn agriculture system), cacao (Theobroma cacao) cultivation under shade trees, and the homegarden. These traditional agroforestry systems almost entirely meet a family's needs for food and wood, and generate at least 62% of family income. Improving the productivity of these systems could help to reduce pressure on the forest in southern Belize.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

    17.
    Construction of new roads in rural areas is closely linked to market accessibility and economic growth. It also leads to exploitation of natural resources that may accelerate deforestation. These conflicting effects of an improved road network on rural development and depletion of forest resources present a serious challenge to policy makers interested in sustainable development. This paper investigates the effects of road networks on biological and socio-economic behaviour. The analysis was conducted by using a non-linear bio-economic model for a community in southern Zagros, Iran where they manage the adjoining forest according to traditional rules. Data for the model were obtained through village surveys and published resources. The model followed a holistic approach by incorporating a number of livelihood activities, such as, crop cultivation, goat husbandry, charcoal production and hiring out of community labour, along with several logical resource constraints. It was run over a period of 45 years. The results showed that new roads can either fuel forest degradation or contribute to forest protection depending on the choice of policy options. The study concludes that construction of new roads should be accompanied by policies aimed at higher state controls over newly accessible forest areas through regulatory measures, creation of new non-farm employment opportunities and strengthening of traditional institutions through providing extension services for local communities and facilitating NGO involvement so as to minimize the adverse effects on forest resources.  相似文献   

    18.
    Swidden cultivation can contribute to deforestation and land degradation, which can subsequently result in a number of serious environmental problems. This paper examines the economic and social potential of agroforestry systems and the barriers to their widespread adoption, as a land use alternative to swidden cultivation, which may potentially help protect local forest. The Gunung Salak valley in West Java, Indonesia is presented as a case study. Based on farmers’ and experts’ assessment, costs and benefits have been estimated, which show that the two investigated agroforestry systems have higher net present value and benefit-cost ratio (B/C) than the two swidden cultivation systems. Tree ownership also creates more permanent rights to farmland and is prestigious in the community. Agroforestry products (fruit, vegetables etc.) have high monetary value and help strengthen social cohesion when shared with neighbors. However, farmers are reluctant to implement agroforestry. Stated reasons are related to both culture and capacity. Farmers practicing agroforestry are less involved in forest clearing and forest products collection than swidden farmers indicating that it may contribute positively to conservation of local forests. Increasing the adoption of agroforestry farming in the study area will require support to overcome capacity constraints.  相似文献   

    19.
    The dynamics of the Atlantic Rainforest loss and recovery are still not fully understood despite its long history of human occupation. In this study, we investigated changes in an Atlantic Rainforest region due to major biophysical and human proximate causes. First, we modeled land-cover and land-use changes from 1962 to 2000, including deforestation and forest regrowth, and thereby simulated future landscape trajectories to assess their possible effects on the conservation of forest species of the Ibiúna Plateau, a region located in Southeastern Brazil within the Atlantic Rainforest biome. We modeled four scenarios (status quo, random, lawenforcement, and land-use intensification) and simulated their resulting landscape trajectories for the year 2019 using DINAMICA. The landscape dynamics in the study region were particularly intense. During the first period of 1962–1981, the rate of forest regrowth (3% year−1) was greater than the rate of deforestation (2% year−1), whereas in the latter period of 1981–2000, increasing urbanization and the spreading of rural establishments resulted in more deforestation (2.9% year−1) than regrowth (1% year−1). These dynamics imprinted a heterogeneous landscape, leading to the predominance of progressively younger secondary forests with increasingly less capacity of hosting sensitive forest species. The influence of proximate causes on the dynamics of deforestation and forest regrowth showed consistent patterns, such as higher forest regrowth rates near rivers, on steep slopes and far from dirt roads, whereas losses in young secondary vegetation and forest were far from rivers, on gentle slopes and near urban areas. Of the modeled scenarios, only the law enforcement scenario may lead to the recovery of a network of interconnected forest patches, suggesting that simply the enforcement of current forest laws, which prohibit deforestation on unsuitable agricultural areas and along river margins and establish a minimum of 20% of forest remnant per rural property, may effectively favor forest species conservation in the short term (two decades) without the need of any forest restoration effort.  相似文献   

    20.
    About 90% of the annual losses of tropical rain forests are caused by transformation into arable land. Most of the cropping activities on the former forest land are characterised by low input, partly shifting cultivation practices, leading to fast degradation of the lands which are finally abandoned owing to infertility. Success in protecting land from further degradation is determined by the economic viability of the respective system. Therefore, sustainability of agricultural systems depends on their economic sustainability. Intensive plantation cropping on former rain forest land appears to offer such an incentive to prevent the land from further degradation by employing the best technology available.Examples of intensive oil palm cultivation as a sustainable cropping system, in terms of economy and ecology, are given. Oil palm cultivation in a suitable environment outyields most annual crops and reveals a significant potential for efficient conversion of solar energy.With the employment of sound agronomic measures the present production potential can be fully realised and new techniques in the production of tissue cultured planting material provide further improved economic viability and environmentally sound cropping systems. Such an intensification offers excellent prospects for reducing the rate of deforestation in the humid tropics.  相似文献   

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