Forests Introduction and Historical Context. International Forestry John Sessions

Transcription

1 Forests Introduction and Historical Context International Forestry John Sessions

2 Overview What is a Forest? Importance of Forests Forest Classification Human Impact on Forests Historical Overview Sources: FAO SOTWF 2011, 2012, Global Assessment 2005

3 What is a Forest Forest = a habitat with a high density of trees FAO definition = 10% crown cover and greater than 0.5 ha. Tree= woody plant with main stem > 15 ft

4 Why Are Forests Important Commercial Products Energy Production Nonwood Products Food Production Regulate Water Runoff Carbon Stores Biodiversity

5 Characteristics of Forests Dominated by Trees Presence of a Canopy Availability of Water Great Biodiversity Complexity

6 Complexity Conifer Simplest Structure Single Layer Deciduous Forests Upper and lower layer Rain Forests Three or more layers

7 Several Systems of Classification Climatic Zones and Principal Types of Trees (United Nations Environment Programme) Distance From Equator and Altitude (World Wildlife Fund) Condition (Primary Forest, Secondary Forest, Plantation Forest) Function (Production Forests, Protection Forests) Ownership (Public, Private, Community)

8 Trees Distribution Main Drivers - Temperature - Precipitation Main Regions Boreal Temperate Tropical

9 Forest Types Boreal Forest Conifer Dominated, Evergreen dominated Temperate Forest Conifers, BroadLeaf, Evergreen, Deciduous - Tropical Forests BroadLeaf Dominated Evergreen, Deciduous

10 Hardwoods and Softwoods Hardwoods Historically hardwoods were given their name because they were typically more difficult to saw than softwoods but some are softer. Most Hardwoods are angiosperms (flowering plants) Most Softwoods are gymnosperms (reproduces from exposed seed Most Hardwoods have broad leaves and most softwoods have needle-like leaves Many Hardwoods are deciduous, but some are evergreen Most Softwoods are evergreen, but a few are deciduous Hardwoods sometimes designated as porous and have vessels while softwoods are non-porous and do not have vessels. Most Hardwoods have shorter wood fibers than softwoods,

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18 Arrival of Modern Trees ~300 million years Conifers ~120 million years Broadleaf ~25 million years Grasses ~100 million years Gondwana separates ~3 million years North/South America joined

19 Human Impact on Forests Mediterranean 3000 years China 3000 years Southern Europe, England Roman Empire Northern Europe- Middle Ages Japan 1500 years North, South America 300 years, but perhaps much longer West Pacific 200 years

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22 Near East and Mediterranean Covered by forest 5000 years ago Bronze age and iron age brought new ways to cut trees Ancient forests cut for heating, cooking, construction, conversion to agriculture, ship building Poor agricultural practice, uncontrolled grazing -> soil erosion, loss fertility and eventual desertification in many areas

23 Northern Africa Cleared by Romans 200 BCE to 500 CE Depleted during Arab conquest in 700 and 900 CE.

24 Europe 2000 years ago forests covered 80 percent of Europe Forests cover 50% (est.) before Middle Ages Deforestation rate remained high during until 19 th century when wood was replaced by fossil fuels Era of modern forestry begins in Germany, about 1700 following concerns about sustainability Now forests cover about 34% of Europe (outside Russia) About the same as the US, 33% and Canada, 34%

25 Eastern Asia China 4000 years ago forests are thought to cover more than 60% of China, pop < 2 MM 200 BCE forest had declined to 50%, pop 20 MM 1400 forests had declined to 25%, pop 65 MM 1840 forests are 17%, pop 450 MM 1950 forests are < 10%, pop 540 MM 2011 forests are 22%, pop 1400 MM

26 Eastern Asia Japan Extensive deforestation before 1700 Recognized value of sustainable forestry about same time as Germany, 1700 Emergence of industrial economy that can import timber resources Now almost 70% forested

27 South Asia India 1500 pop 100 MM twice Europe Since 1500 more than 50% of forest lost to land conversion to agriculture 2010 pop 1200 MM, 23% forested and slowly increasing with planted forests

28 Southeast Asia Prior to 1800 shifting cultivation was primary driver of forest clearing Under colonization rapid increase of cutting commercial timber and conversion to commercial crops Perhaps 40 MM hectares cleared during Commercial harvest prohibited in Thailand. Deforestation and forest degradation continues in many areas, some legal, much reportedly illegal.

29 Central/South America Perhaps 75% forested prior to Europeans Amazon Recent evidence suggests western Amazon forest is larger now than prior to 1500 CE due to population collapse following disease from Europeans Expansion of cattle ranching, conversion to agriculture accelerated during late 1800 s to late 1900 s. Significant conversion to agriculture continues. 49% forested - Population increased from 5 MM in 1500 to 420 MM now

30 Africa Few statistics before colonial time During colonial time, log selective logging increases with log flows to Europe Now increased log flows to China and India Population increase in Africa putting pressure on fuelwood (80% of wood), crop/grazing land. Population MM Population MM (4x in 60 years) Population MM (2x in 40 years)

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34 Is Deforestation Inevitable? Encouraging National Examples Policy Wealth/Choice Sharing knowledge Investment Technology

35 Our Next Meetings will Explore Boreal, Temperate and Tropical Forests George Taylor Climate and Forests Ed Jensen Boreal and Temperate Forests Badege Bishaw Tropical Forests