GLOBAL DEFORESTATION The Fate of a Renewable Resource

Deforestation  Deforestation is the net reduction of forested area on our planet  One of the greatest forces of global environmental change (mainly over the past 200 years)  Reduced forest cover by human action has a huge impact on global biodiversity

Why We Deforestaion occurs  Forests are cleared, degraded and fragmented by:  Timber harvest  Conversion to Agriculture  Road building  Human caused fire  Removal for heating and cooking fires  Urban development

How Much Forest Do We Have  Originally, almost half of the United States, three- quarters of Canada, almost all of Europe, the plains of the Levant, and much of the rest of the world were forested  Currently about 34 million Km 2 of forest remains

What’s Left?  About ½ of our original forests are gone  Each year another million hectares are removed (approximately the size of Panama)  22% of the world’s old growth forest remains  About ¼ of the world’s land area is still forested  Seven countries including: Russia, Brazil, USA, Canada, China, Indonesia, Dem.Rep. Congo, account for 60% of the world’s forested land

Frontier Forests of the World Red = Frontier Forests, 8,000 years ago Green = Frontier Forests Today Pink = Current non-frontier forests

How Fast is it Disappearing?  Most developed Countries currently have close to zero net deforestation  Deforestation in Europe was largely completed before the end of the 1800s  Most current deforestation currently occurs in the tropic and most severely in poor countries  In Latin America and Asia deforestation rates are about 2% per year  At this rate by 2080 we will have only ¼ our current forested area

Key Definitions  Deforestation: The conversion of forest to another land use or the long-term reduction of the tree canopy cover below a 10 percent threshold. Deforestation implies the long-term or permanent loss of forest cover and its transformation into another land use.  Primary forest: is a forest that has never been logged and has developed following natural disturbances and under natural processes, regardless of its age.  Secondary forests: are forests regenerating largely through natural processes after significant human or natural disturbance, and which differ from primary forests in forest composition and/or canopy structure.  Disturbed forests: Any forest type that has in its interior significant areas of disturbance by people, including clearing, felling for wood extraction, anthropogenic fires, road construction, etc.  Frontier forests: large, ecologically intact, and relatively undisturbed forests that support the natural range of species and forest functions (WRI definition).  Forest plantation is one established by planting or/and seeding in the process of afforestation or reforestation. It consists of introduced species or, in some cases, indigenous species.

Importance of Forests Forest Products  In many poor areas wood is still commonly used for cooking.  Building materials  Furniture  Pulp and paper products (including cardboard and cellulose)  Source of numerous non-wood products, including bark, dyes, fibers, gums, incense, latexes, oils, resins, shellac, tanning compounds & waxes. Fruits, nuts and berries are harvested as food. Maple syrup is an example of a unique non-wood product from the sap of the maple tree.

Ecosystem Services  Influences climate: captures carbon, reduces atmospheric CO 2, involved with hydrologic cycle  Where forests are cut increased erosion and flooding may be issues and may result in ultimately a drier climate  Protection of soil and nutrients  Foster biodiversity (loss of potentially valuable species for medicine or agriculture)

Tropical Deforestation  about 100,000 km2 are deforested each year, and another 100,000 km2 are degraded  Estimates are constantly improving, based on satellite imagery  Causes of deforestation in the Amazon  Cattle ranches 65-70%  Small-scale, subsistence agriculture 20-25%  Large-scale, commercial agriculture 5-10%  Logging, legal and illegal 2-3%  Fires, mining, urbanization, road construction, dams 1-2%

The State of Tropical Forests  In many countries the rate of deforestation is accelerating.  For example, most of the forested areas of Bangladesh, India, the Philippines, Sri Lanka and parts of Brazil's rain forest could be gone by the end of the century.  Brazil contains about 3.5 million km 2 of tropical forest. This is equivalent to 30% of the world's total

Biodiversity and the Amazon  Amazonia has been characterized as the "single richest region of the tropical biome."  A single hectare of rain forest near Manaus yielded 235 tree species over 5 cm in diameter and 179 species over 15 cm in diameter.  There are 2000 known species of fish in the waters of the Amazon Basin. This is eight times the number found in the Mississippi River system and 10 times the number found in all of Europe.

The Impact of Roads  Roads usually accompany timber harvest, in order to move logs to sawmills and markets.  Even when tree harvest is highly selective, and much of the forest remains, it has been found that the roads themselves have numerous adverse side-effects  As forests become more open through thinning, they become drier, and more susceptible to fire  In wet areas roads become pathways for surface runoff, and carry sediments into streams, destroying aquatic life  Culverts installed where roads cross rivers often block fish passage  roads allow hunters and poachers much greater access, resulting in the large and very serious bushmeat trade

Forest fragmentation by roads in Central Africa. This study shows that 42% of forest area in the six countries is within 10 km of a road and more than 90% is within 50 km of a road

Forest Management and Recovery Rotation Harvest: the goal typically is to maximize annual harvest while ensuring that the area harvested is consistent with forest regrowth rates and total area under management Results in a second harvest of the same forest plot after some years. The length of time between successive harvests of a forest is called the rotation length

Forest Management and Recovery Multiple Use: Forests on federal and state lands are usually managed according to multiple use principles This means that in addition to forest harvest, the land is available for recreation and maintains a healthy forest ecosystem Managing to protect biodiversity and to restore pre- settlement conditions are relatively recent goals

Forest Management and Recovery Indigenous Use: Forests may be used by indigenous people for:  subsistence hunting  forest harvest  as a place to live

Forest Management and Recovery  If left to nature forests will re-establish themselves  This process is called Succession and typically takes from years depending on tree growth rate  Tropical forest are very vulnerable as they are difficult to rehabilitate. Soil is quick to be leached of nutrients and may be lost through erosion

Restoration Vs Rehabilitation  Forest restoration may seek to restore the system to a near-natural or completely natural state, or to restore many aspects of the structure and function of an undisturbed forest  The latter is usually referred to as rehabilitation, to emphasize that the desired endpoint is not necessarily that of pre-settlement conditions

Forest Management and Fire  Fire is suppressed in many forest ecosystems to:  Protect valuable commercial wood  Protect human homes in or adjacent to forest  Protect old growth ecosystems  In many cases fire is positive to a forest ecosystem  Some trees require fire to reproduce (jack pine)  Other trees require thinning of the understory to repopulate (Oak)  Fire suppression created a build up of dry fuel  This increases the intensity of a forest fire and may cause greater ecosystem damage