General Themes (I) Lecture 12

Transcription

1 General Themes (I) Lecture 12 1

2 Sustainability Source: Adams, W.M. (2006). "The Future of Sustainability: Re-thinking Environment and Development in the Twenty-first Century." Report of the IUCN Renowned Thinkers Meeting, January

3 Scale Consideration of sustainability is always confounded by defining scale Temporal Spatial Where are the boundaries? 3

4 Forests are important! Forests are the natural climax vegetation on more than half of the world s land surface. The world s forest area is about 3.8 billion ha. About one third of world s land area which is not covered with ice. Canada: 7% of world s forest land area. BC: 1.7% of the world s forest land area. 4

5 What is a tree? A perennial woody plant characterized by one main stem or trunk bearing a more or less distinct and elevated crown of branches. Trees are generally larger than shrubs (six metres). 5

6 Trees Fall Into Two Main Groups Angiosperms Enclosed seeds, flowering plants. Gymnosperms Naked seed plants, or cone bearers (conifers). 6

7 What is a Forest? A forest is a vegetative community dominated by trees and other woody perennials. Images courtesy of Bart van der Kamp 7

8 What is forestry? Forestry is the science, art and practice of understanding, managing and using wisely the natural resources associated with, and derived from forest lands. Forestry is the science and craft of creating, managing, using, conserving, and repairing forests and associated resources to meet desired goals, needs, and values for human and environment benefits. SAFnet Dictionary via Wikipedia 8

9 Boreal Forest Biome 9

10 Boreal Forest Biome Boreal forests are characterized by long severe winters and short cool summers with only frost free days. Precipitation is low ( mm) falling largely as snow. However, available soil moisture is high. Stands in the boreal are also fairly uniform in terms of age (large areas of even-aged forest), height and diameter distribution. Low growth rates (1-1.5 m 3 /ha/annum) 10

11 Boreal Forest Biome Bogs (muskeg) are common in poorly drained glacial depressions typified by sphagnum moss and ericaceous shrubs. Breakdown of organic matter and nutrient release is slow and the forest floor is covered by deep organic litter. Over 80% of above ground nitrogen is found in forest floor forest floor litter. 11

12 Temperate Forests 12

13 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 13

14 Temperate Forests Natural Disturbances Wind Wildfires Insects Earthquakes Volcanic eruption 14

15 Temperate Forest Biome Temperate forests account for 44 percent of the world s forest area and tropical and subtropical forests 56%. Plantations both temperate and tropical comprise about 7 percent of all forests Produce about 35% of world roundwood 15

16 Temperate Forest Biome Commercial productivity is higher than the boreal averaging 4-5m 3 /ha/annum but has been increased considerably in many areas through forest management. 16

17 MAI=3.33m 3 /ha/annum Mean Annual Increment (MAI) = Volume/Age (m 3 /ha/annum) Maximum MAI = 550/85 = 6.47m 3 /ha/annum 17

18 Temperate Forest Biome 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 all areas there is a long history of exploitation for commercial timber. 18

19 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. 19

20 Tropical Rainforest Biome Copyright The McGraw-Hill Companies 20

21 Tropical Rainforest Biome ucmp.berkeley.edu Temperature varies little throughout the year Average annual temperature is around 20 degrees Celsius Rainfall is relatively evenly distributed Annual precipitation is generally more than 2500 mm No distinct season Tree growing season is year round 21

22 Tropical Rainforest Biome Tropical rainforests are very diverse biologically: - 60% of all plant species - 80% of all insect species - 90% of all primates - hundreds of thousands, possibly millions, of species yet to identify. 22

23 Tropical Rainforest Biome Characteristics of many tropical trees include: buttressed trunks large leaves in the lower strata of the forest and small leaves in the upper strata thin bark large fleshy fruits 23

24 Tropical Rainforest Biome Tropical forests generally exhibit low commercial productivity of only m 3 /ha/annum E.g. Brazilian Amazon has over 50 billion m 3 of timber but log production is only about 4 million m 3 /annum. 24

25 Tropical Rainforest Biome When tropical rain forests are cleared of vegetation they do not regenerate easily and do not regain their original structure and composition. Nutrients are leached from soils that are already nutrient deficient. Soils become compacted and harden (laterization). Waterlogging and erosion occur 25

26 Tropical Seasonal Forest Biome Copyright The McGraw-Hill Companies 26

27 Tropical Seasonal Forest Biome The tropical moist deciduous (seasonal) forests are similar to the evergreen tropical rain forest in terms of temperature, growing season and diversity of species composition. However, they are typified by pronounced dry and wet (monsoon) seasons. Many species lose their leaves during the dry season. The zone is extensive in South America, South-central Africa, India and parts of South-east Asia. 27

28 Tropical Seasonal Forest Biome It is an increasingly important area for the establishment of fast-growing, intensively managed plantations. MAI m 3 /ha/annum (Goncalves et. al, 2012) Eucalyptus plantation and pulp mill in Bahia state, Brazil flickr.com 28

29 Savana Copyright The McGraw-Hill Companies 29

30 Savanna pixabay.com Savannas (dry forests) are very extensive. They are the transition between the tropical high forests and grasslands. Monthly mean temperatures average above 20 degrees Celsius and annual rainfall varies between 700 and 1200 mm. Trees are slow growing, of poor form (twisted) and short. 30 Trees are drought resistant, fire resistant and browsing resistant.

31 31

32 Laurentide ice sheet NOAA 32

33 Global wind patterns 33

34 Topographical map of Canada 34 c1.staticflickr.com

35 Up to 5000mm 200mm Up to 1600mm 35

36 Growing Space The integration of all the factors that trees need to grow Sunlight, Water, Nutrients, Physical space 36

37 Even-Aged vs. Uneven-Aged Stands Even-aged stands are comprised of trees that are predominantly the same age Such stands generally originate following a stand-replacing disturbance Uneven-aged stands are comprised of trees of several (or multiple) ages Such stands generally originate following small-stage disturbances that kill some, but not all, of the trees 37

38 Photosynthesis How the ecosystem captures energy Photosynthetic mechanism Foliage Chloroplasts (chlorophyll) 38

39 Release energy Respiration Priorities for energy Respiration Photosynthetic mechanism (Reproduction) Primary growth Secondary growth and compounds 39

40 Whittaker (1975) An ecosystem is a functioning system that includes an assemblage of interacting organisms (plants, animals, and saprobes) and their environment, which acts on them and on which they act. 40

41 Trophic Levels Level 1: Plants and algae make their own food and are called primary producers. Level 2: Herbivores eat plants and are called primary consumers. Level 3: Carnivores which eat herbivores are called secondary consumers. Level 4: Carnivores which eat other carnivores are called tertiary consumers. 41

42 Ecosystems are Dynamic Structure is always changing Autogenic change Without outside influence Are diseases autogenic? Allogenic change Outside agent 42

43 The adaptive cycle (Holling, Gunderson & Ludwig, 2002) Old forest Young forest Disturbance 43

44 Complex Adaptive Systems Dynamic network of interactive systems Mycorrhizal connections Energy flow Nutrient flow 44

45 Not a super-organism No natural selection at the community level Need competition Individual level Plants rarely exhibit mutualism No food web between plants Plant animal interactions can Redundancy 45

46 Role of Disturbances Resistant Ecosystem property of remaining essentially unchanged Resilient Ecosystem property of recovering quickly Recovering to what? 46

47 Ecosystem Management Maintaining a healthy system What is healthy? The heart of sustainability Meeting the needs of today and tomorrow 47

48 Green Fire documentary c1.staticflickr.com A land ethic reflects the existence of an ecological conscience, and this in turn reflects a conviction of individual for the health of the land. Health is the capacity of the land for self-renewal. Conservation is our effort to understand and preserve this capacity. The land ethic simply enlarges the boundaries of the community to include soils, waters, plants, and animals, or collectively: the land. A thing is right when it tends to preserve the integrity, stability and beauty of the biotic community. It is wrong when it tends otherwise. shepherdexpress.com/ 48