2. Deforestation

2.1 Introduction

Forests are a widespread and easily exploited renewable resource. Humans use forests for fuel, construction materials, paper, wildlife habitat, and erosion control. Forests are found in most humid and sub-humid regions of the world, from the tropics to the tundra. Forests have been severely depleted in many areas of the world. In some cases, as in many MDCs , forests have recovered in recent decades because of silvicultural practices. In many LDCs, rapid population growth and rising fossil fuel prices have caused great increases in demand for wood, primarily for fuel.

2.2 Tropical Rain Forests

In tropical areas, deforestation is proceeding rapidly to make way for other land uses (Figure 3.1 ). The Amazon rain forest covers about 7.0 million square kilometers. Brazil, which occupies 4.9 million square kilometers of tropical forest, is interested in developing its capability to produce fuel from biomass, as well as to increase agricultural output and meat production. Brazil constructed a major highway into the Amazon to facilitate development and encouraged settlement with tax credits (suspended in 1988-89).

The history of deforestation in the tropics began in the 1700s with the harvesting of indigenous tree crops (e.g. rubber and hardwoods) and the replacement of original forest by crops ( West Indies - sugar, Brazil - coffee and sugar, and Malaysia - rubber). Vast expansion of rice cultivation in lower Burma resulted in the destruction of about 90,000 square kilometers of rainforest between 1850 - 1950. In south and southeast Asia, crop cultivation may have consumed 216,000 square kilometers of closed forest and 62,000 square kilometers of open forest. During this period the demand for land to grow crops and settle people was matched by a rising demand for forest products: hardwood timber such as teak and mahogany for ship construction and furniture; softwoods for general constructional purposes; and wood for fuel.

From 1950 to 1990, the world's population doubled from 2.5 - 5 billion. With this drastic increase in population came an unprecedented strain on the world's forest resources, primarily concentrated in the tropical LDCs. The United Nation's Food and Agriculture Organization estimates that the developing world lost nearly 200 million hectares of forest between 1980 and 1995. About 20 million hectares of this loss was offset by reforestation.

Humans have been using tropical forests and their resources in basically three ways. Forests have been traditionally used by people indigenous to this environment for food, fiber, fodder, medicine, and building materials. This type of use normally involves minimal alteration to the ecosystem as consumption of forest resources is low. Traditional shifting agriculture causes greater disturbance to tropical forests. This type of human land-use is found in all tropical forest regions. It involves the clearing and preparing of small patches of land (0.5 to 2.0 hectares) for agriculture through a combination of tree felling, slashing the understory vegetation, and fire. Fire releases the nutrients stored in the vegetation to the soil surface providing a fertile medium to grow crops. However, agriculture can only be practiced for a few years because of the effect of leaching on soil fertility. When the soil nutrients become too limiting for crop growth, the patch is abandoned and secondary forest naturally regenerates on the land over several decades. Shifting agriculture has been practiced in many tropical forest systems for hundreds of years without any signs of longterm environmental degradation. Rubber tree planatations are an enhanced version of the shifting agriculture system. Instead of the prepared land being used for crops, rubber farmers enrich the regeneration of the secondary forest by planting rubber trees amongst the naturally occurring tree seedlings. These systems can provide farmers with fruit and tapped rubber for several decades.

Today most of the Earth's tropical forests are being cut for commercial timber production. Trees are logged either by selectively cutting trees or by clear cutting. Once cut, the land may regenerate forest naturally or with the help of a variety of human management techniques. In some cases, regeneration of a secondary forest is halted or slowed by the use of the land for livestock grazing. Scientific evidence suggests that intensive logging of tropical trees can result in severe environmental damage and loss of biodiversity. Soils exposed after logging are easily eroded by runoff. Eroded sediment can pollute streams which in turn influences the survival of aquatic plants and fish. Computer models have shown that clear cutting can modify the energy and hydrologic balance of areas resulting in local or regional climate change.

In the last few decades, the following four factors have played a major role in reducing tropical rain forests:

(1) Expanding Population and Resettlement Schemes - cultivators are nibbling away at forest in order to create more land. Also expanding numbers of shifting cultivators are forced to shorten rotations leading to permanent change. In Brazil, government backed schemes have moved people from over-populated areas to the Amazon basin.

(2) Ranching and Pasture Development - in Central America pasture development is one of the main factors causing forest clearance. These farmers want to supply cheap beef for domestic use, and beef for export to the USA for pet and fast foods.

(3) Fuelwood and Charcoal - clearing for fuelwood and charcoal is of major global importance. Approximately 1.5 to 2.0 billion people rely on wood for warmth and cooking.

(4) Timber Trade - countries like Malaysia, Indonesia and the Philippines are exporting large amounts of tropical hardwood for use in MDCs.

2.3 Services Provided by Tropical Forests

Biodiversity - Forests contain a diversity of species, habitats, and genes. They provide the gene pool that can protect commercial plant strains against pests and contain biological chemicals that may be used for drugs or other commercial products. The wild relatives of avocado, banana, cashew, cacao, cinnamon, coconut, coffee, grapefruit, lemon, paprika, oil palm, rubber, and vanilla are found in tropical forests. Scientists estimate that 170,000 plant species occur in the tropical rainforest many of which have never been scientifically classified.

Water - Forests absorb rain water and release it gradually to streams, preventing flooding. Removal of forests may drastically influence a region's hydrology.

Erosion - Forests keep soil from eroding into rivers. Siltation of reservoirs costs the world economy about 6.0 billion dollars a year in lost hydroelectricity and irrigation water. Siltation is also reducing the productivity of estuaries and coral reefs.

Fisheries - Forests protect fisheries in rivers, lakes, estuaries, and coastal waters. Three fourths of fish sold in the markets of Manus, Brazil have fed on the fruits, litter, and seeds of forest vegetation.

Climate - Forests stabilize climate and create their own unique microclimates. Deforestation releases the greenhouse gases carbon dioxide, methane and nitrous oxide, and accounts for 25 % of greenhouse gases released into the atmosphere. This release of gases into the atmosphere enhances the greenhouse effect resulting in global warming.

Recreation - Forests serve people directly for recreation.

2.4 Temperate Forests

Temperate forests are generally found in the middle latitudes where precipitation is great enough to support tree growth. In milder temperate climates, forest are normally dominated by deciduous tree species. Coniferous species of trees dominate temperate forests that exist closer to the poles and experience colder winters. Some temperate areas, on the western coast of continents, support highly productive temperate rain forests where abrupt changes in elevation enhance seasonal rainfall.

Mid-latitude countries have a long history of harvesting their temperate forests (Figure 3.2). Countries like Britain and France harvested the majority of their forests hundreds of years ago. Harvesting of temperate forests in North America began shortly after this area was discovered by Europeans. In the United States, about 60,000 square kilometers of forest was cleared by 1850 and 660,000 square kilometers by 1910. Canada, New Zealand, South Africa, and Australia harvested about 400,000 square kilometers of forest and woodland by the year 1990. Today the most significant harvest of temperate forest is occurring in Eastern Russia. In this region, 40,000 square kilometers of coniferous and deciduous trees are being cut down annually to generate much needed capital to support the Russian Federation's weak economy.

At the turn of the century, the last large stands of uncut trees in North America were found in the temperate rain forests of Washington, Oregon, northern California, and British Columbia. The moist mild climate of these areas of the west coast promote the growth of huge long-lived trees, like redwood, western red cedar, Douglas fir, hemlock and Sitka spruce. Today less than 10 % of these trees are uncut, and the proposed cutting of the last remnants of these forests is being resisted by environmentalists. In British Columbia, the voices of concerned citizens in the early 1990s caused the government to take action to protect specific areas of temperate rain forests for future generations.

2.5 Forestry In British Columbia

2.5.1 Introduction

Canada has a total land area of 997.0 million hectares and of this almost half (417.6 million hectares) is forested, although the types of forests vary throughout the country. Although, many people believe that the only major deforestation crisis exists in the tropics, there is some evidence to suggest that there is also a crisis in Canada. A 1993 comparison of Canada with Brazil showed that in Brazil one acre of forest in cut or burned every 9 seconds and in Canada this value is one acre every 12 seconds. The importance of this must be realized as Canada represents almost 10 % of the world's forest cover.

British Columbia, contains the richest abundance of forests in Canada, out of the 11 major forest regions in the country, 6 can be found in BC, which is more than any other province. Nearly two thirds of the province's 94.8 million hectares is covered with forests. The province is home to almost 70% of the bird species and 74% of the mammal species that live in Canada, most of which are forest dwelling.

2.5.2 History of British Columbia's Forests

The use of forests in North America began conservatively, became exploitive and is now becoming progressively more conservative again. Forestry has followed four stages in the last century, since Canada, and particularly British Columbia became more populated. With increased population came an increasing need for forest products and agricultural land, and therefore deforestation. There are the four suggested stages:

• The Pioneer Period, pre-1912
• The Transition Period, 1912-1947
• Development of the Sustained Yield Regulation, 1947-1978
• The Modern Era, 1978-present

During the Pioneer Period, forests as a resource were thought to be limitless, a resource to be exploited. Forests were a source of government revenue and employment, a time when people believed that forest regeneration would somehow occur on its own. At that time, there was no scientific or ecological knowledge which prevented this type of exploitive logging.

In 1912 the Transition Period began. This period began a haphazard attempt at conservation, reforestation and forest management. High lead logging was common on the Coast, and selective logging was started in the Interior. In this period there was still little public concern for the forest as a resource. Nurseries were introduced for reforestation, and cut control regulations were initiated.

This led into the third period, that of the Development of the Sustained Yield Regulation. These decades, from 1947-1978, started a forced commitment to forest regeneration. This was done through changing unrestricted sale to a timber sales program with a controlled annual cut and assured regeneration. Tree seedlings were available to owners of forested land for free, and more nurseries were built. In the Interior, silviculture practices were started that tried to maintain the forest system during and after logging, by protecting the understorey as well as the residual stand and the seed source for natural regeneration. In 1964, the government introduced stumpage fees. These fees required the logging companies to take the process of regeneration seriously, only being compensated for their cut after the appropriate post-logging area treatment was completed. Regeneration became a condition for those holding Tree Farm Licenses as well. The cost of the ir regeneration was recovered through lower stumpage fees.

The Modern Era, 1978-present, began with a new Forest Act in 1978. This Act introduced a Forest License which required holders of such license to submit a management and working plan prepared by a professional forester which contained a commitment to forest regeneration. This plan continued until 1987, with the cost of regeneration credited against stumpage fees. Since 1987, a preharvest silviculture prescription (PHSP) has been required for every site. This PHSP is meant to ensure a new crop of trees will be planted after harvesting. Also since 1987 logging companies have been required to return each logged site to a free growing state where the planted or naturally regenerated trees are taller than competing vegetation. Up to 20 % of the site, however, is allowed to be permanently scarred and compacted with landings and skid trails that may never grow forests again.

It is expected that the annual timber harvest will decline in the near future in many areas of the province as past and current timber harvesting activities are changing the composition of BC's forests. The new forests are younger and have smaller trees and in the future these stands are expected to be harvested at an earlier age and therefore will contain a lower volume per unit area than the original forest.

2.5.3 Methods of Deforestation

There are various resources harvested from our forests such as food, fish, wildlife and timber. In Canada, approximately one million hectares of forest land are harvested annually for timber, and 240,000 of those hectares are harvested in British Columbia. Of several silviculture and timber harvesting systems used in forestry, the most common technique is clear-cutting. In Canadian forests, clear-cutting is suitable for areas containing trees of similar size and age. In fact in BC, clear-cutting is the method of choice over 90 % of the time, except in the drybelt portion of the province.

Clear-cutting is a silvicultural practice (growing and tending forests) and a harvesting method. It removes all trees from an area of forest, except seedlings and occasional saplings. Under an even-aged system (tress of similar size and age) the trees are cut at the same time. This generates another even-aged area of trees once new growth occurs. The regeneration of even-aged systems is more successful than uneven-aged systems. They grow rapidly because of the even distribution and high intensity of sunlight. The clear-cut method is commonly used in even-aged systems because it establishes a growing pattern and timber quality preferred for wood production. Even-aged forests are cut at a particular size depending on the purpose they intend to serve. For example, the production of goods such as tissue paper, book paper, cardboard, and newsprint, are made from a young forest area. Large pieces and saw logs used for construction and making plywood requi res the clearing of an older forest. Here, a forest is grown for 60-120 years between clear-cuts.

Clear-cutting is also defined as the removal of forest conditions, ecologically speaking, which are created by the existence of the trees. Consequently, clear-cutting has become controversial, particularly in large areas where it has been found to have environmental impacts on plant and animal habitats, soil, and hydrology. Slash burning and site preparation are often associated with clear-cutting, however in British Columbia slash burning and site preparation are often associated with clear-cutting, however in British Columbia slash burning has become less common because of public concern about smoke and subsequent soil damage. The practice of clear-cutting creates the most ecological change in harvested forest landscapes. Economics plays a large role in the practice of clear-cutting because it is most often less expensive and more profitable than any alternate harvest system. The international lumber and pulp markets are very competitive and are also the providers of tho usands of jobs. Therefore, the forest industry depends on low production costs that are another reason clear-cutting is the method of choice.

Another system of harvesting is selection. Selection harvesting removes mature trees from a stand containing trees of different ages and is done mostly in the interior of British Columbia. This method opens a stand allowing remaining trees to attain more sunlight, nutrients, and moisture. The practice of seed-tree harvesting clear-cuts trees except a few strong and healthy ones which supply seeds for natural vegetation. This technique works best with tree species that are shade intolerable. The practice of felling is the most dangerous of all harvesting techniques. It is done by the use of power saws and special care must be taken to avoid damaging the trees that are cut and those nearby because damage to a tree seriously reduces its value.

2.5.4 Old Growth Forests

Old growth forests are a major issue for the forestry industry throughout Canada and particularly in British Columbia. These forests are the source of potential economic wealth, but destroying them could have a greater impact than losing a few old trees.

There has not been one exact definition for old growth forests, as they can differ depending on climate, site characteristics, forest type and history of disturbances. Old growth forests generally have one or more of the following characteristics:

Very Large Trees. This is highly dependent on climate, site characteristics etc., so is not a sole way of evaluating old growth forests.

Very Old Trees. This factor also depends on many factors especially the area in which trees grow. The temperate rainforests of the coast commonly reach ages over 250 years old, while trees in the interior may only reach 100 years in age.

Complex Ecosystem Structure. A multilayered canopy is one characteristic that is said to be true of old growth forests.

High Species Diversity. Many old-growth forests are have a lot of species diversity, more so than a newer or second growth forest.

Deep Litter Layer. Old growth forests generally have a lot of accumulation of dead organic matter on the forest floor when they have remained undisturbed by fire for centuries. Again this factor is highly dependent on climate characteristics.

In British Columbia, there have been many protests to protect the old growth forests, particularly the coastal temperate rainforests that occur on Vancouver Island. Each year almost 200,000 hectares of old growth forest are cut. There have been changes, the government of British Columbia has established an Old Growth Strategy and they have developed a Commission on Resources and Environment which is to design a land-use strategy and to organize and facilitate negotiation processes where conflict occurs.

Some progress has been made, after a major campaign, the government divided the Carmanah Valley, in half, the bottom for a park and allowing the upper areas to be logged (which may have some impacts on the bottom part of the valley).

Clayoquot Sound on Vancouver Island, has been a focal point in BC and globally over forest value and issues of environmental and economic sustainability. Clayoquot represents 262,000 hectares of which 244,000 are forested. Over 30,000 hectares have been logged to date, and only 39,100 hectares are in protected areas, and the remaining 90,400 hectares of commercially productive land is mainly old growth forests.

In the Okanagan Valley forests that are 80 to 100 years are considered to be old growth. The Lodgepole pine in the higher elevations and to some extent the Douglas Fir and Ponderosa Pine in the lower elevations are fire climax species which need fire to open their cones and release seeds and to prepare the ground for future growth. If the fire does not burn the forest, pinebark beetles which are common in the area likely will. Due to these factors it is rare to see forests in the Valley beyond an age of 100 years.

2.6 Environmental Impacts of Deforestation

As forests are removed by logging there are many impacts on other aspects of the region, soils are eroded and impoverished, species become extinct, the hydrological regime of an area is changed, and climate of an area can be altered.

2.6.1 Biodiversity

Scientists believe that over 50 to 80 % of the Earth's species live in the tropical rainforests. With so many different species in such a small area, populations of individual species are therefore small and are at tremendous risk when their habitats are fragmented because they become more vulnerable to predators, competitors, pests, disease and bad weather. Even the extinction of just one species can lead to the extinction of many others that depend on it for pollination, seed dispersal, food or defense. The tropics, however are not the only forests that are vulnerable to losses in biodiversity , many forests are being wiped out in North America and along with it Canada's biodiversity is being threatened.

The loss of biodiversity is not only important to other species in the forest, but it can have a dramatic affect for people across the globe for numerous reasons:

Humans depend on such a few species for food, and often scientists are required to return to these crops wild ancestors to obtain fresh germ plasm to create new varieties of these food crops and protect existing varieties from epidemic diseases. Many of these ancestors reside in tropical rainforests so scientists want to protect the forests to preserve the wild varieties of these food crops.

In addition to preserving the wild ancestor agricultural species, forests are also a source for future gene revolutions for agriculture and also a source of natural insecticides as many plant species have evolved chemicals to repel insect pests.

There are many species that have pharmaceutical value. According to scientists at the National Cancer Institute, over 70 % of the promising anticancer drugs come from plants in tropical rainforests, and only a few million plant species have been evaluated for medicinal purposes. In fact, one such plant, the rosy periwinkle has been responsible for a 99 % remission for childhood leukemia victims. Many of species have not yet been analyzed for their potential value and further many species have not yet been discovered which may be valuable for both pharmaceuticals and for future gene revolutions. Scientists collecting species in the Upper Carmanah Valley in British Columbia have found that of all the species being collected approximately 40 % are new species that have never been discovered previously.

North Americans have noticed a declining population of songbirds and other birds are at risk. This is because many of the birds that summer in North America, winter in the tropical rainforests of Latin America and their habitat is being destroyed there. The loss of these birds is not just an aesthetic problem, many of these birds eat mosquitoes, worms, caterpillars, and other insects that destroy crops and northern forests. Not to mention the risk to other species as some birds pollinate plants and spread seeds.

There is no way of knowing the rate of extinction because no one knows the exact number of species that live on Earth. Some scientists estimate that if deforestation rates continue at current levels, over one quarter of the world's species will be headed for extinction over the next 50 years.

There has been research, however, to show that in small clear-cut areas there may actually be an increase in biodiversity if enough vegetation is left and care is taken during harvesting to ensure regeneration of both plants and animals living in the harvested area. This is common in many cool temperate and northern forests.

In British Columbia, management practices, including leaving 10 % of the area intact, using native vegetation for regeneration, leaving buffer zones to protect streams and other such water channels, and promoting a number of tree species will contribute tot he overall diversity of other vegetation and wildlife in the area.

2.6.2 Climate Change

Deforestation can have an affect on both local and global climate depending on the size and method used to clear the forest.

In a local area, the affects of deforestation on climate depend on the size of the area cleared. Forests increase surface roughness and affect local climate by influencing air current and increasing the amount of evapotranspiration that occurs due to turbulent mixing at a rough surface. Further, rainforests have a relatively low albedo (the fraction of total radiation encountered that is reflected by a surface) and much of the energy is absorbed at the surface which then goes into evaporating and transpiring much of the rainfall and this water vapor forms clouds which then fall as further precipitation. When a tropical rainforest is cut down, many of these natural processes are reduced or eliminated and consequently the amount of rainfall is also decreased. Not only is the amount of precipitation affected when a forest is cut down, other aspects of the microclimate are also affected including humidity, radiation balance, temperature, and moisture in the air are affected. When tr ees are removed in a clear-cut method, the amount of solar radiation changes. Because black soil attracts more sunlight than green trees do, the temperature within the microclimate increases during the day. However, night-time longwave radiation from the soil to the atmosphere also increases resulting in cooler night temperatures in the clear-cut area. In moist areas, such as the tropical rainforests and the humid Pacific Northwest, the moisture of the air these climatic changes increase photosynthesis and therefore species regrowth is fairly rapid however, in dry continental areas such as the Okanagan, these microclimatic changes can have a negative impact on forest regeneration.

On a global scale, tropical deforestation can contribute to the much publicized greenhouse effect. Several aspects of tropical deforestation have a profound affect on increasing greenhouse gas concentrations:

Forests that are felled and burned release stored carbon and nitrogen in the form of carbon dioxide and nitrogen oxides. Humid forests release substantially more carbon than dry forests and dry forests normally have much less of a litter layer from which decomposition occurs..

Cattle ranching can also contribute to global warming as cows release methane by bacterial fermentation in the rumen. Methane is a much more powerful greenhouse gas than carbon dioxide and cattle numbers have been increasing over the last decade.

Forest that are felled and left to rot also release great quantities of methane.

Oxidation of soil humus, which occurs after a forest is removed releases carbon dioxide into the atmosphere.

Deforestation also influences the greenhouse effect because not only of addition of greenhouse gases, but the forests are vital in removing carbon dioxide from atmosphere through photosynthesis, an important regulatory mechanism.

2.6.3 Soil Degradation

There are numerous impacts on soil due to deforestation and harvesting practices.

The nutrient cycling of the soil can be affected because the uptake by trees is eliminated, and decomposition is affected by changes in the soil temperature and moisture. Soil fertility is often increased due to these factors. When the flush of nutrients is excessive, however, many of these nutrients can be leached away. Excess nutrients can also lead to extensive growth of herbs and shrubs for several years after the area is harvested which can interfere with the early growth of planted seedlings. Most changes in nutrient cycling in the soil are also temporary, as internal transfers will maintain an equilibrium.

Erosion and sediment transport also increase after deforestation because of increased surface flow of water and these sediments end up in lakes and streams which depending on the timing of increased sediment load can affect spawning gravels and can reduce visibility for feeding, clog gills, and change water quality for aquatic organisms. If the eroded material is coarse, it can alter stream channels by increasing the width and in some cases cause flooding. Erosion in the tropical rainforests is a big concern because there is only a thin layer of soil to begin with and so the loss of any of soil makes it difficult to re-establish any sort of vegetative cover, either in the form of crops or forests.

Soil left unprotected from deforestation is affected by processes such as mass wasting. Not only does the removal of vegetation alter the hydrologic regime, but decaying roots also result in the loss of the mechanical reinforcement. There are numerous changes to the soil caused by roading, tractors and skidders which all act to compact the soil and change the distribution of mass of soil on the slope. Since British Columbia is a province with many mountainous slopes, any factors that can increase the occurence of landslides are of great concern. In 1990, there were six debris slides on Philpott Road, Kelowna which buried a home and killed 3 people. The area around Philpott road had been both clear- cut and selectively logged with many logging roads and skid trails in the area. An investigation that was launched into the causes of these landslides implicated logging practices as three of the five major causes of the landslides, the other two factors being unstable terrain and heavy rain.

A study site, Gates Creek located just outside of Vernon in the Okanagan shows the results in one harvested site of the impacts on soil. Following stumping, the soils were reported to be much denser and less penetrable than undisturbed soil, resulting in a reduced growth of Douglas-fir after five years, but no reduction was measured in the height of lodgepole pine, which tends to demand little from the soil, and is able to grow well in a number of different soil conditions.

2.6.4 Hydrology

There are many impacts to the hydrological system of an area due to the harvesting of trees and to the construction of roads and skid trails into a forested area.

The forest canopy intercepts much of the water from rainstorms, and this water is then either evaporated back to the atmosphere or it falls gradually from leaf to leaf, eventually reaching the ground where it is captured by the soil and litter layer and is released slowly into rivers and streams or back to plants. With an undisturbed forest, the rivers run clear and flow all year long due to this efficient process.

Forest logging often leads to an increase in the frequency of both floods and droughts. The removal of forests increases the total flow of water into rivers and creeks as there is increased surface runoff, increased water movement through the soil profile and a lack of infiltration, all of these factors can lead to increased probability of flood occurrence. Droughts are also influenced by deforestation, because water is not absorbed into the soil, so it is not released slowly into the rivers, which can become shrunken or dry up during periods of low rainfall. These factors affect agriculture, fishing, irrigation and hydroelectric power. Robertson River on Vancouver Island has the appearance of being all dried up even though the total flow has been increased.

In Northern climates, snow characteristics are also affected. Because of the lack of forest cover in clear-cut areas, the snowpack is often deeper and it melts sooner in he spring because of the increased solar radiation reaching the area.

Water quality of nearby streams and lakes can also be affected by deforestation. Many of the problems, however, can be avoided by leaving strips of forest next to the water. First, inorganic suspended sediments can affect primary productivity in the stream by blocking light for photosynthesis. Clear-cutting can result in one or two years of increased nutrient inputs to streams which can improve productivity but if the stream is small, they may reach undesirable levels. Dissolved oxygen can also be decreased due to the addition of organic debris from logging practices. Finally water temperature can also be altered due to the reduction in flow, changes in stream characteristics and due to lack of shade that was provided by the trees.

In British Columbia a large salmon industry once thrived in rivers and coastal waterways. Today, the natural reproduction of chinook salmon is seriously damaged due to the clear-cutting on steep slopes. Carnation Creek on Vancouver Island was the site of extensive studies on the impacts of forestry on fisheries. The site was studied for 16 years (from 1971 to 1987) which included a prelogging monitoring stage and a postlogging monitoring stage. The studies showed that after the logging periods the numbers of salmon that entered the creek were lower than the prelogging period.

2.6.5 Indigenous People

All tropical rainforests have been the homes to indigenous groups for thousands of years. These groups live entirely in and off the tropical rainforest and know how to do so without destroying it. They know everything about food plants, medicinal species, edible insects and collection of wild honey and they know how to use the rainforests on a sustained basis. In fact indigenous groups groups were the ones who originally discovered 75 % of the plant derived drugs that are used today. It is ironic that the very people who know so much about living in harmony with the forest are the ones who are threatened. Not only are forest dwellers being wiped out due to the competition for space within the rainforest, but settlers bring with them diseases to which the tribal groups have no immunity, and with the diminishing populations of these people, valuable knowledge about the forests are being lost.

The effects on indigenous people in North America is not as great although there have been many disputes between the loggers and the natives over land claims of old growth forests. One such example is Meares Island.

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