Lecture 5. Forests of the world (III) Temperate forests

Transcription

1 Lecture 5 Forests of the world (III) Temperate forests 1

2 The Temperate Forests 2

3 The Temperate Forests Climate Temperature correlates with distinct seasons. Precipitation is higher than the boreal ( mm). The growing season is longer than in the boreal (200 days or more) 3

4 The Temperate Forests Forests are more complex than boreal forests in terms of species composition and structure uneven aged in many cases with multiple canopy and vegetation layers. Nutrient cycling is more rapid than in the boreal and more nutrients are stored in biomass.» Why? warmer 4

5 The relative position of canopy and crown classes. Canopy strata are the horizontal layers of tree crowns which are separate from higher and lower layers. Crown classes refer to within each stratum: D = dominant, C = codominant, I = intermediate, S = suppressed. Retrieved from: Oliver, C. D., & Larson, B. C. (1996). Forest stand dynamics. McGraw-Hill, Inc.. 5

6 Northern Patagonia, Argentina 6

7 The Temperate Forests The dominant plant species are broadleaved deciduous trees but species composition varies from pure hardwoods through mixed forests to pure conifer. Where coniferous components exist they can be very valuable commercially Coastal BC and the US Pacific Northwest Eastern Canada and the United States: white pine (Pinus strobus) 7

8 Pinus strobus 8

9 Temperate Rainforest Near Vancouver 9

10 The Temperate Forests Natural Disturbances Wind Wildfires Insects Earthquakes Volcanic eruption 10

11 Malcolm Knapp UBC research forest 11

12 Windthrow 12

13 13

14 Rangitoto, New Zealand 14

15 The Temperate Forests European forests are less species diverse than their North American counterparts. Species include a broad spectrum of temperate hardwoods: oaks (Quercus spp.), elm (Ulmus spp.), ash (Fraxinus spp.), beech (Fagus spp.), lime or basswood (Tilia spp.), maples (Acer spp.) 15

16 The Temperate Forests Although in western Europe all forests are secondary and total areas are low, the forests are intensively managed and production of roundwood is high. Sustainable forest management practices 16

17 The Temperate Forests This is the zone in which the practice of forest management developed and where forestry as a profession had its roots. First forestry school was established at Hungen, Germany, in 1787 In North America, the Biltmore Forest School and the New York State College of Forestry, in

18 The Temperate Forests This is the area occupied by the world s industrialized nations. In Asia and Europe most of the forest has been cleared for agriculture and urban infrastructure. In the industrialized countries of the zone the consumption of industrial forest products is very high. In all areas there is a long history of exploitation for commercial timber. 18

19 The Temperate Forests There is virtually no primary forests remaining in the temperate mixed forest zone. - China s forests have been cleared for intensive agriculture for over 4000 years. - Europe s forests have 2000 year history of exploitation are confined to relatively small areas of secondary forest. - Japan s forests are largely second-growth or plantations. In the mountains of Korea some intact forests remain. 19

20 The Temperate Forests Plantations, both exotic and indigenous, are of growing importance in the temperate mixed forest zone. What are some of the advantages of growing exotic species? What are some of the disadvantages of growing exotic species? 20

21 Loblloly pine (Pinus taede) 21

22 Lodgepole pine (Pinus contorta) in Northern Patagonia 22

23 Concerns about forest plantations Loss of biodiversity No consideration of wildlife habitat Herbaceous understory killed Monoculture Impact on water table Trees are very inefficient water uses Genetic selection exacerbates this concern Salinization 23

24 Pine plantation in Southeastern U.S. 24

25 Slash pine (Pinus elliottii) plantation in Argentina 25

26 Loblloly pine (Pinus taede) Row thinning 26

27 Measuring impacts of intensive forestry in US South Soil severely degraded and eroded by cotton plantations in 18 th and 19 th centuries. Natural invasion of pine (and some planting) started restoring sites. Since site quality is improving how do you measure site degradation of intensive pine management. Increasing at a decreasing rate 27

28 Planting trees is the same as plantation? 28

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31 Exotic pine plantations dominated by radiata pine (Pinus radiata) in New Zealand, Australia and Chile. 31

32 Ten countries with the largest area of productive forest plantations Prepared by Philippe Rekacewicz assisted by Cecile Marin, Agnes Stienne, Guilio Frigieri, Riccardo Pravettoni, Laura Margueritte and Marion Lecoquierre. 32

33 The Temperate Forests: plantation The world s largest plantation programme is in southern China. Consists of both indigenous and exotic species including pines and eucalypts. Plantations are very productive and rotations short: Southeastern United States 15-20m 3 /ha/annum, 15 years for pulpwood, years for sawlogs. New Zealand and Chile m 3 /ha/annum, years for sawlogs. 33

34 The Temperate Forests Commercial productivity is higher than the boreal averaging 4-5m 3 /ha/annum but has been increased considerably in many areas through forest management. What is MAI? Mean Annual Increment 34

35 MAI=5.71m 3 /ha./annum MAI=3.33m 3 /ha/annum Mean Annual Increment (MAI) = Volume/Age (m 3 /ha/annum) 35

36 Maximum MAI = 550/85 = 6.47m 3 /ha/annum 36

37 Summary Most of the temperate forest are mixed species deciduous Disturbances play an important role in temperate forests dynamic Plantations: management, productivity and rotation 37