Natural heritage tipe bioma di dunia.pptx

Natural heritage tipe bioma di dunia.pptxNatural heritage tipe bioma di dunia.pptx

1. COMPARATIVE ECOSYSTEM ECOLOGY: FORESTS 16/11/2013

2. FORESTS Major forest types Coniferous forest Temperate broadleaf forest Tropical forest Forest structure Coniferous forest structure Deciduous forest structure Tropical forest structure Forest stratification and animal life Function 16/11/2013

3. FORESTS Major forest types There are three general, but highly diverse major forest types worldwide: coniferous forests, temperate broadleaf forests, and tropical forests. 16/11/2013

4. Coniferous forests Conifers are cone-bearing gymnosperms—resinous trees with dark green, needle /scale-like leaves. Most conifers are evergreen i.e. year-round foliage. They photosynthesize year-round; whenever conditions are favorable 16/11/2013

5. The coniferous forest type has five distinct ecosystems(as described here for North America): The taiga and boreal forest - the largest and most expansive coniferous forest which is generally limited by the summer and winter positions of the Arctic front. The taiga can be further subdivided into four habitat types: two of which are ecotonal regions of boreal forest-tundra habitat & mixed hardwood-conifer forest along the northerly and southerly limits, respectively. The remaining two habitats are open boreal woodland (black spruce in damp areas) and the main boreal forest (continuous stands of white spruce and balsam fir) 16/11/2013

6. Temperate needleleaf rain forest - the most l uxuriant of the coniferous forests, features trees of unparalleled size and longevity . Overstory trees can be more than 50 meter tall and have diameters greater than two meters . Longevity is generally greater than 500 years . These characteristics are related to the excessive moisture regimes (more than 600 cm annually with about a third of this occurring as fog drip) and mild temperatures. 16/11/2013

7. 3. Woodlands - characterized by the presence of pinyon pine and juniper and a well-developed understory. This type has been subjected to much human disturbance. 4. Southern pine forests – found in the southeastern United States and are not representative of climax vegetation. They occur on sandy soils and are maintained by frequent fires . 16/11/2013

8. Montane coniferous forests -these forests are associated with mountainous regions. The subalpine forest is found at the higher elevations and is dominated by spruce and fir species. The montane forest is found at lower elevations and is dominated by pines and some spruces . Montane forests are relatively warmer , wetter , more species-rich , and more productive than subalpine forests. The existence of coniferous ecosystems is typically related to regions of modest environmental rigor, which have cool temperatures , low rainfall , soils of poor quality , and/or fire frequency . 16/11/2013

9. These generalizations must be taken with some caution. High rainfall and mild temperature regimes characterize the temperate rain forest , yet the soils are thin and poor in nutrients . The southern pine forests occur in regions of ample moisture and warm temperatures , yet owe their existence to nutrient-poor, sandy soils and the prevalence of fire . 16/11/2013

10. 1. Taiga and boreal forest Winter , the dominant season, is severe and the small amount of precipitation the region receives comes in the three warm months. However, because of the cold that inhibits evaporation , the region is moist all year Found at latitude 50 o - 70 o North. 16/11/2013

11. 2. Temperate needle-leaf rain forest Occupying the continental west coast of North America between 40 o and 60 o N from southern Alaska to California – a humid temperate region with abundant rainfall. Moisture-laden westerly winds move in from the Pacific, meet the barrier of the Coast Range, and rise abruptly – rain & snow. During the summer, when winds shift to the northwest, the air is cooled over chilly northern seas. Although the rainfall is low, cool air brings in heavy fog – adding more moisture. 16/11/2013

12. 3. Woodlands In parts of western North America, where the climate is too dry for montane coniferous forests - pinyon-juniper woodlands. Pinon-juniper woodlands occur from the Front Range of the Rocky Mountains to the eastern slope of the Sierra Nevada foothills. These woodlands have been greatly disturbed by livestock grazing, fuel harvesting, and exclusion of fire. Such disturbances increase the density of trees and reduce the cover of grasses. 16/11/2013

13. 4. Southern pine forest The pine forests of the southeastern United States are in an area with hot, humid summers and mild winters . They fall into two groups: the outer coastal plain mixed forest or temperate broadleaf evergreen forest, and the southeastern mixed forest of southern pine and oak. The coastal plain forests are mostly secondary forest resulting from fire , deforestation, or deliberate forest management. Large areas of southeastern mixed forest likewise are successional, maintained by lumber management practices 16/11/2013

14. 5. Montane coniferous forests 16/11/2013

15. The air masses that drop their moisture on the western slopes of the Coastal Range then descend the eastern slopes, gain heat , and absorb moisture , creating conditions that produce the Great Basin Desert. The same air rises up the western slopes of the Rocky Mountains, cools, and drops moisture again, although far less than on the Coast Range. Here, in the Cascade, Wasatch, Rocky, and Sierra Nevada mountains, several coniferous forest associations develop. In the southwestern United States these coniferous forest occur between 2500 and 4200 m elevation. Rocky Mountains (winters are long and snowfall is heavy) = subalpine forest 16/11/2013

16. Temperate broadleaf forest 16/11/2013

17. The temperate broadleaf forests have been used extensively by mankind for centuries; most of what exists today is second- and third-growth forest. In light of the daily, and winter and summer climatic extremes that must be endured by species in these forests, the use of the term “ temperate ” is somewhat misleading . They are exposed to droughts and, in places, flooding . In spite of their intemperate “temperate” environment, temperate forest ecosystems are able to maintain high productivity. 16/11/2013

18. The temperate broadleaf forests occur in three general forms: Temperate deciduous forests – Temperate deciduous forests once covered large areas of Europe, China, parts of South America, the Middle American highlands, and eastern North America. The deciduous forest of Europe and Asia have largely disappeared, cleared for agriculture and settlement . The dominant trees include European beech, oak, ashes, birches, and elms. Because of glacial coverage during the ice ages , the diversity of tree species in European deciduous forests is lower than that of North America and China . 16/11/2013

19. 1. Temperate deciduous forests Deciduous forests are leafless during the winter; in northern regions they remain leafless for most of the year. 16/11/2013

20. 2. Temperate woodlands These forests are represented by oak, oak-sagebrush, or oak-pine communities in the southwestern U.S. and Mexico. 16/11/2013

21. 3. Temperate broadleaf evergreen rain forests - these forests occur in subtropical areas, such as the Florida Keys, Australia, South America, etc. Species include as magnolias, palms, eucalyptus, and live oaks. The oaks and other trees support an abundance of epiphytes and the lichen, Spanish moss. The temperate broadleaf forests have been used extensively by mankind for centuries; most of what exists today is second- and third-growth forest. In light of the winter and summer climatic extremes that must be endured by species in these forests, the use of the term “ temperate ” is somewhat misleading . 16/11/2013

22. 3. Temperate broadleaf evergreen rain forest 16/11/2013

23. Tropical forests experience a steady year-round temperature of about 23 o C and a wide variation in rainfall, climatic conditions that are reflected in a diversity of vegetation patterns. The tropical region contains twice as many Holdridge life zones as the temperate zone and seven times the number of the boreal zone. 16/11/2013

24. The tropical forests occur in four forms: Tropical rain forest - the tropical rain forest is found in at least 30 to 40 types including the monsoon forest , the evergreen savanna forest , the evergreen mountain forest , the tropical evergreen alluvial forest , and the lowland tropical rain forest . They once formed a worldwide belt around the equator. Today, the largest continuous rain forest is found in the Amazon basin ; other major areas are in west and central Africa and the Indo-Malaysian regions. These forests are found where temperatures are constantly high and every month is wet . They support nearly half of all known plant and animal species. 16/11/2013

25. Tropical montane rain forest - found in mountainous regions above the lowland tropical rain forest. The lower montane forest is found on the highest mountains and is an ecotone between the broad leafed-dominated lowland forest (with an uneven billowing canopy ) and the small leafed-dominated upper montane forest. The montane forest has a lower, more even canopy , a dense lower canopy , and smaller trees with gnarled limbs heavily covered in bryophytes and ferns. 16/11/2013

26. 3. Tropical seasonal forest - these forest grade into semi-evergreen and semideciduous seasonal forests. They are characterized by less rainfall , more variable temperatures , and a dry season during which about 30% of the upper canopy species lose their leaves . 16/11/2013

27. Tropical dry forest - these forests make up about 42% of all tropical forests, with the most found in Africa and on tropical islands. Most of the original forests have been converted to agriculture and grazing lands or have regressed through disturbance to thorn woodland, savanna, and grassland. These forests experience a dry period, with the length depending on latitude. The greater the distance from the equator , the longer is the dry season . During the dry period , trees and shrubs drop their leaves . Before the start of the rainy season , which may be wetter than the wettest time in the rain forest , the trees begin to leaf out . 16/11/2013

28. Tropical rain forests The mean annual temperature is about 26 o C, the mean minimum rarely goes below 25 o C, and the difference in temperature throughout the year is less than 4 o C. Trees species number in the thousands. A 10 sq. km area of tropical rain forest may contain 1500 spp. of flowering plants and up to 750 spp. of trees. Heavy rainfall occurs throughout the year, not less than 100 mm in any month for 2 out of every 3 years. Rain forests support 5 to 10 million species of arthropods – at least ! 16/11/2013

29. Forest structure The structural features of a forest are built upon the vertical stratification created by the amount of space occupied by trunks , branches , twigs , and leaves at different levels or heights above ground . There are four general strata: Canopy - intercepts the bulk of solar radiation. Lower or understory tree canopy . Understory shrub layer . Herbaceous or forest floor layer . 16/11/2013

30. Tropical forests may also have an emergent layer. All strata are not necessarily found in all forests. The highest temperatures and most light are found in the upper canopy . Temperatures tend to decrease through the lower strata and change through the 24-hour period. Light intensity is attenuated through the forest canopy to only a fraction of full sunlight at the forest floor. The lowest humidity in the forest is a few feet above the canopy , where air circulation is best and the highest is near the forest floor . Humidity in the temperate deciduous forest interior is highest in summer because of plant transpiration and poor air circulation . 16/11/2013

31. STRUCTURE 16/11/2013

32. Dead wood in the form of large standing dead trees or snags, downed trunks and limbs, and dead branches on living trees, makes up an important component of the deciduous and coniferous forest ecosystems. 16/11/2013

33. The amount of dead wood changes with tree mortality and disturbances and never achieves an equilibrium. Woody litterfall usually increases over time and becomes most prominent in old deciduous and coniferous temperate forests. However, temperate broadleaf deciduous forests have a lower input , a faster decay rate , and thus a lower accumulation of dead wood and nutrients on the forest floor. Standing dead trees provide essential nesting and den habitat for cavity-nesting birds and mammals. Decaying logs are an important rooting medium for tree seedlings , especially conifers. 16/11/2013

34. Decaying logs, may make up 10 to 20% of the ground surface in forests. Decaying wood absorbs both water and nutrients (water retention increases as decomposition increases) Dead wood is inhabited by a host of insects living beneath the bark and in decaying wood—bark beetles, wood-boring beetles, carpenter ants, and termites—that are preyed upon by insectivorous vertebrate and invertebrate predators. Rodents, reptiles, and amphibians , especially salamanders, use well-decayed logs as burrows and runways. Thus, the elimination of standing and fallen dead trees, as if often done, can impoverish animal life in the forest. 16/11/2013

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36. Coniferous forest structure Coniferous forests fall into three broad classes according to growth form that influences their structure: Pines with straight, cylindrical trunks , whorled spreading branches, and a crown density that varies from the dense crowns of red and white pine to the open thin crowns of Virginia, jack, Scots, and lodgepole pine. Spire-shaped evergreens , including spruce, fir, Douglas-fir, and (with some exceptions) the cedars, with more or less tall pyramidal open crowns , gradually tapering trunks, and whorled, horizontal branches. Deciduous conifers , such as larch and bald cypress, that have pyramidal, open crowns and shed their needles annually. 16/11/2013

37. Coniferous forests Vertical structure and stratification in coniferous forests 16/11/2013

38. Vertical structure is not well developed in many coniferous forests- Because of high crown density and deep shade, the lower strata are often poorly developed in spruce and fir forests. Pine forests with a well-developed high canopy may lack lower strata. However, older stands and forests of open-crowned pines many have three strata: an upper canopy , a shrub layer , and a thin herbaceous layer . The litter layer in coniferous forests is usually deep , poorly decomposed , and lies on top of instead of being mixed with the mineral soil. It can inhibit the germination and development of woody understory and herbaceous plants. 16/11/2013

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40. Temperate deciduous forest structure Highly developed, uneven-aged and older even-aged deciduous forests usually consist of four strata: 1. The upper canopy of dominant tree species. 2. Below the upper canopy is the lower tree canopy of saplings and understory trees . 3. The shrub layer . 4. The ground layer consisting of herbs, ferns , and mosses . The litter layer is variable , depending on the lignin-to-nitrogen ratio . It ranges from a thin, rapidly decomposing layer in sugar maple and yellow-poplar forests to more slowly decomposing oak leaves. 16/11/2013

41. Temperate deciduous forests Vertical structure and stratification in eastern deciduous forest 16/11/2013

42. Even-aged stands (trees all of similar age) of trees are typically the results of fire , clear-cut logging , and other large-scale disturbances . These often have poorly developed strata early in their development because of dense shade. The low tree and shrub strata are thin , and the ground layer may be poorly developed , except in gaps, until the stand approaches maturity. 16/11/2013

43. Old-growth coniferous and deciduous forest structure Old-growth forests are often, compositionally and always structurally, different from earlier successional stages. Old-growth consists of a wide range of tree sizes and spacing that results in a high degree of patchiness and heterogeneity . This patchiness results from some degree of disturbance over time within the stand. Old-growth stands are dominated by long-lived individuals and contain significant amounts of woody debris and downed logs. Old-growth stands possess more diversity in structure and function than secondary forests, and are characterized by highly evolved complex relationships between animals and plants. 16/11/2013

44. Some forests (particularly eastern deciduous forest) may achieve old-growth stage at 150- to 200-years. Other species and stands may not arrive at old-growth stage until much later. 16/11/2013

45. Old-growth coniferous forests, especially boreal and western coniferous forests, support microcommunities of algae and lichens in the canopy. These rather complex microcommunities include primary producers , consumers , and decomposers . Cyanophycophyllous lichens fix atmospheric nitrogen. Organic nitrogen lost through leaching from lichens combines with canopy moisture to form a dilute organic solution that in turn is taken up by microorganisms and other canopy epiphytes. Part of this microbial production is consumed by canopy arthropods. 16/11/2013

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47. Tropical rain forest structure The tropical rain forest has been divided into five general layers: Emergent canopy - Uppermost or emergent layer that consists of trees 50 to 60 m or more high. Their crowns rise above the rest of the forest to form a discontinuous canopy. Canopy - Main canopy that consists of a more or less continuous layer of trees 24 to 36 m high. Lower canopy - Lower tree stratum that consists of a more or less continuous layer of trees 15 to 24 m high. Shrub and young tree layer - A generally poorly developed layer of shrubs and young trees that can exist in the deep shade of the understory. Ground layer - A layer composed of tall herbs and ferns . 16/11/2013

48. Stratification of tropical rain forests in often poorly defined with no clear demarcation between layers, except for the emergent canopy layer . This results from a combination of tree species that have the same growth plan but different sizes , or species that mature at different heights . Other individuals become dwarfed because of unfavorable growing conditions. A conspicuous part of the rain forest is plant life dependent upon trees for support, including epiphytes , climbers , and stranglers . 16/11/2013

49. Epiphytes attach themselves to a host tree and obtain their nutrients from air, rainwater, and organic debris trapped by their aerial roots or leafless bases. Some epiphytes are important in recycling minerals leached from the canopy. Climbers are vinelike plants that reach the tops of trees and expand into the form and size of the tree crown. Climbers grow prolifically in openings, giving rise to the image of the impenetrable jungle. Stranglers start life as epiphytes. They send their roots to the ground and increase their stems in number and girth until stranglers encompass the host tree and claim the crown limbs as support for their own leafy growth. 16/11/2013

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