Presentation on theme: "LECTURE XIV FORESTRY DEVELOPMENT. Planning Forestry Development The world's natural forests are experiencing land use change due to both direct and."— Presentation transcript:
LECTURE XIV FORESTRY DEVELOPMENT
Planning Forestry Development The world's natural forests are experiencing land use change due to both direct and indirect causes.land use change However forest related land use changes have complex socio-economic, cultural and political foundations. Thus one cannot assume simple and static cause-effect relationships.
Direct causes of change Direct causes include immediate human land use activities that change forest cover in a local area.land use activities Key drivers include: Agricultural expansiongricultural Infrastructure development Wood extraction Climate changelimate change Fire and Alien invasive species.invasive species
Agricultural expansion Agricultural expansion has been identified as a major factor in almost all studies on deforestation. Agricultural deforestation In the 1990s, according to the United Nations Environment Programme (UNEP), 70% of total deforested areas were converted to permanent agriculture systems. Increases in food production have been at the expense of millions of hectares of forest.
Infrastructure development Infrastructure development (road construction, dams, mining, power stations, etc.) is an important direct cause of forest-related land use change.land use change Road construction particularly, is a key factor in triggering deforestation as it tends to open up areas of undisturbed, mature forests to pioneer settlements, logging, and occasionally unsuitable forms of agriculture.deforestation agriculture The ensuing fragmentation also increases the exposure of forests to the dangers of poaching, alien invasive species, fires and pest outbreaks.poaching invasive species
Infrastructure development Large dams construction has led to the loss of forests and wildlife habitat, species populations and the degradation of upstream catchment areas.habitatcatchment areas Mining corporations and individual miners are also notably responsible for the clearance of large areas of forest in some countries.
Wood Extraction Another direct cause of forest land use change is wood extraction from natural forests.land use change Despite the growing importance of plantations as a source of wood supply, wood extraction in the form of commercial timber, poles, fuelwood, and charcoal continues to degrade mature natural forests in many parts of the world. In the case of commercial logging, tree removal methods are frequently destructive and unsustainable. This is often the case on steep slopes and in sensitive ecosystems such as mangroves.ecosystemsmangroves
Fire Fires are a key driver of forest land use change.land use change Yet, fire is a paradox as while it can cause extensive ecological, economic, and social damage it can also be extremely beneficial through nutrient recycling and regeneration. Fire is a natural part of the forest cycle with some tree species, notably Lodgepole Pine and Jack Pine being able to germinate only after they have been exposed to fire. Burning quickly decomposes organic matter into mineral components that cause a spurt of plant growth, and can also reduce disease in the forest. Fires in contrast cause considerable environmental, health, economic and social damages and cause forest loss and degradation.
Climate Change Today's fragmented and degraded forests are vulnerable to climate change with up to 30% of forests likely to be affected by climate change by the year 2050 according to an Intergovernmental Panel on Climate Change report.Intergovernmental Panel on Climate Change Higher temperatures and changes in rainfall threaten tropical montane forests, boreal forests and Mediterranean-type, fire-prone forests.temperaturesrainfallmontane Effects of greenhouse gases can affect the processes of budding, flowering, fruiting, leaf senescence, frost hardiness, wood quality, branching and insect susceptibility.greenhouse gases The risk of serious pest and disease infestations increase with more changes in climate. Extreme weather events, such as droughts and floods, pose other risks to forest ecosystems.ecosystems
Alien invasive species As the global movement of people and products spreads, so does the movement of plant and animal species from one part of the world to another. Often these alien species are economically important and enhance the production of forest commodities in many parts of the world.alien species In some cases species introduced intentionally become established in the wild and spread at the expense of native species, affecting entire ecosystems. ecosystems
Alien invasive species Worse still is invasive by alien species that are introduced unintentionally, such as disease organisms that can devastate an entire tree species (e.g. Dutch elm disease and chestnut blight in North America) or pests that can have a major effect on native forests or plantations (e.g. gypsy moths and long-horned beetles). As global trade grows, so does the threat from devastating invasive species of insect and pathogen.trade These could fundamentally alter natural forests and wipe out tree plantations, the latter being especially vulnerable because of their lower species diversityspecies diversity
Indirect causes of change Result from social and institutional processes that may indirectly impact forest cover from a local, national, or international level. Forest land use change is seldom straightforward, often being driven through a complex mix of socio-economic, cultural, and political factors.land use change Such factors in turn result from the combined actions, decisions and behavior of multiple agents ranging from national governments to international financiers to impoverished landless people.
Indirect causes of change Prominent Indirect causes include: Poverty. Market failure and perverse incentives, Market failure Corruption Inappropriate state policies and institutional failure Population pressure and Population pressure
Poverty Poverty is popularly cited as a principal driver of forest loss and degradation. In reality, however, the evidence for such a straight-forward relationship is weak and sometimes conflicting. The empirical evidence for the historical relationship between economic growth, a growing middle class, consumption levels and forest decline is perhaps a little better understood but also remains weak and fragmented.economic growthconsumption
Poverty What is evident however is that there is a causal relationship, or more accurately several relationships, that need to be better understood. More reassuringly, there is some, yet again fragmented, evidence that no single trajectory is necessarily predetermined and that forest resources, under a range of circumstances, can be managed and utilized in such a way as to contribute to poverty reduction while keeping future options open to retain more and lose less forest biodiversity.biodiversity
Imperfect local, National and International Markets While the contribution of forest goods and services for local livelihoods, national economic growth and as a global public good are regularly highlighted, there is a considerable gap between the acknowledgment of these benefits and how they are actually "valued".economic growth In many countries forests goods and services continue to be undervalued because in the absence of suitable markets, forests, as a land-use, are unable to compete, either with other land-uses or with other sectors such as energy.marketsland-use
Imperfect local, National and International Markets New markets could arise if the provision of key public utilities was viewed slightly differently. For example, clean and reliable water supply requires not only the hard infrastructure of pipes and reservoirs, but also the "green" infrastructure in watershed catchments.watershed Equally production-based incentives for other land-use activities, notably agriculture may also helpagriculture
Absence of Good Governance and Rule of Law Government policies, and how those policies are enforced, both within and outside the forest sector, also ultimately impact on forest land use change.land use change Forest land is still all too often seen as a nationally- owned asset, irrespective of the stewardship that local communities have exercised over the same resource for many years. Inequities in titling and use rights can result in forests becoming a major source of conflict and / or illegal activity.
Absence of Good Governance and Rule of Law While illegal logging and corruption may exist because of pure criminality it can, in some situations, be driven by inappropriate governance structures that turn legitimate concerns or entitlements into illegal activities.
Demographic factors A common myth of the 1990s was that increasing populations was a major underlying cause of forest decline. Available evidence shows that there is no general relationship between population growth and density and deforestation.population growthdeforestation Indeed there are a number of examples in both developed and developing countries of how population increase has been accompanied by increasing tree cover.
Demographic factors Where fuelwood and agricultural land is in much demand and other livelihood options are limited population growth and density can result in increased pressure on forests but this can tend to be quite localized.agricultural Importantly, demographic factors associated with mortality and morbidity, particularly where the HIV/AIDS pandemic is concerned, may be just significant when it come to forest- related land-use changeland-use change
Forest Land use and Agriculture Due to increasing population forest land has been increasingly converted into agricultural land The conversion of forest to agricultural land has had numerous repercussions on the physical and biological environment such as : Increasing the proportion of light energy which is reflected from the land surface Increasing heat transfer to the atmosphere Reduces evapotranspiration from plants and trees Compacting soil (which increases rainfall runoff) Increases erosion, and affects air turbulence (and therefore air movements and winds).
Forest Land use and Agriculture Conversion has led to a loss of biodiversity, movements of species around the world, shifts in local plant and animal populations, the destruction of ecosystems, and the invasion of exotic organisms and diseases into areas where they are not endemic. Agricultural land differs in almost every respect from the original forested land.
Forest Land Conversion Results Chemical, physical and biological alterations in soil After forest conversion, the soil environment is seriously perturbed. The soil structure often becomes compacted, chemical processes in the soil are disrupted, and the diversity and quantity of soil microbes declines. Reductions in biodiversity Very complex ecosystems of the forest are reduced to a simple system of only one or a few crops – cattle, oil palm, or rubber.
Forest Land Conversion Results Depletion of forest ecosystems because of the spread of pathogens and the incursion of exotic species. Because of the prevalence of monocultures and the importation of exotics, agriculture is an inviting feast for pathogens, because there are large stands of uniform hosts. Epidemics in agricultural areas can spread to nearby forests, particularly when they are fragmented. An unexpected effect is that forests may be cut in an attempt to find areas which are not contaminated with the pathogen.
Forest Land Conversion Results Chemical contamination of soil and water and alterations of natural mineral cycles (carbon, nitrogen, phosphorus): In a natural tropical rainforest system, the input of gases and chemicals from the environment is approximately equal to the outgo, but these connections to the outside environment are small compared to the internal cycling of chemicals from vegetation/animals to soil and back again. This cycling is severely altered in agricultural systems since the quantity of vegetation is much reduced and the crop is removed from the system, thus depleting it of essential organic matter.
Forest Land Conversion Results Detrimental alterations in water supplies and in waterways: Irrigation of converted lands leads to salinization (salt deposits), water logging of soil, high nutrient levels in waterways in the vicinity of agricultural areas and water depletion in streams, rivers and other waterways.
Forest Land Conversion Results Displacement of native species and disruption of ecosystems by the introduction of exotic species: Many forest species are threatened by the invasion of exotic species introduced either deliberately as crops and livestock or inadvertently. Many of these have no natural enemies in forest systems and are able to invade the habitats of native species, driving them to population declines or to local extinction. Others act as pathogens, parasites and predators of local species. These biological “invasions” are very extensive and many are irreversible. They at the least disrupt local ecosystems and drive losses in the biodiversity of native species and populations.
Forest Land Conversion Results Soil depletion and loss of productivity: Many farms are established by small-scale cultivators who follow logging roads into the forest. Once roads have penetrated the forest, access becomes easy, and people who are fleeing the poverty of cities or worn-out farms (often rain forest land which has been degraded by agricultural activities) follow and establish small agricultural or ranching operations. When the nutrient level of the land decreases sufficiently, they abandon these farms and penetrate farther into the virgin forest, leaving degraded fields behind. Often this deserted land is unable to regenerate forest and becomes scrub or wasteland.
Forest Land Conversion Results Increase in surface the proportion of light energy which is reflected from the land surface and decrease in surface roughness Leading to temperature increases and decreases in precipitation. All of these consequences are related.