Chap.4 Conditions, resources and the world’s communities 鄭先祐 (Ayo) 國立臺南大學 環境與生態學院 生物科技學系 生態學 (2008) Essentials of Ecology 3 rd. Ed.

2 Chap. 4 Conditions, resources and the world’s communities 4.1 introduction 4.2 Geographic patterns at large and small scales 4.3 Temporal patterns in conditions and resources 4.4 Terrestrial biomes 4.5 Aquatic environments

3 4.1 introduction Individual organisms are affected by conditions and resources. (Chap.3) Because of its influence on both conditions and resources, climate plays a major role in determining the large-scale distribution of different types of community across the face of the Earth.

large-scale climatic patterns Fig. 4.1 the tilt of the Earth on its axis and its rotation around the sun define the amount of radiation striking the atmosphere around the Earth’s surface.

5 Fig. 4.2 the movements of the major ocean currents.

6 Fig. 4.3 the typical influence of topography on rainfall (histogram bars) in the northern hemisphere.

7 Fig. 4.4 biomes

8 Fig. 4.5 the variety of environmental conditions experienced in terrestrial environments

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small-scale patterns in conditions and resources Local variations in topography, Local geology and soil Fig. 4.6 The effect of altitude and latitude on the distribution of biomes. Moving up in altitude is very similar to moving from equator to pole.

11 Fig. 4.6.

Temporal patterns in conditions and resources The composition of communities can change over time scales ranging from hours to millennia, as conditions and resources themselves change. Fig. 4.7 in the 20,000 years since the peak of the last glaciation, global temperatures have risen by about 8oC. Many tree species continue to migrate northward, following the retreat of glaciers.

13 Fig. 4.7 A map showing the spread of two species of forest tree in eastern North American after the retreat of the last ice age glaciation.

14 succession Fig. 4.8 (a) locations of sampling sites (red dots) on 37 and 125 year- old lava flows on Miyake-Jima island, Japan. Sites outside these flows are at least 800 years old.

Terrestrial biomes Tropical rain forest ( 熱帶雨林 ) Savanna ( 疏林 ) Temperate grasslands ( 溫帶草原 ) Desert ( 沙漠 ) Temperate forest ( 溫帶林 ) Taiga (northern coniferous forest) Tundra ( 凍原 )

tropical rain forest 熱帶雨林常綠，全年有開花結果。 – 溫帶落葉林，有特定的生殖季節。 熱帶雨林的土壤貧瘠？ – 熱帶 vs. 溫帶 ( 伐木農耕的比較 )

17 Fig contrasting patterns of fruit or seed production in tropical and temperate forests. (a) tropical rain forest (b) deciduous forest 溫帶落葉林 熱帶雨林

18 Fig contrasting patterns of fruit or seed production in tropical and temperate forests. (a) tropical rain forest (b) deciduous forest 溫帶落葉林 熱帶雨林

19 Fig Animals that feed on the fruit of trees at various times of the year.

Savanna ( 疏林 ) The vegetation of savanna characteristically consists of grassland with scattered small trees, but extensive areas have no trees. In the absence of other controlling factors, these tropical areas would be expected to be covered by forest. There are three main controlling factors. –Grazing herbivores, fire, physical limiting factors (drought, sparse soil nutrients)

21 Fig The distribution of major biome types under the current climate.

22 Fig The potential distribution of major biomes resulting from climate changes associated with an effective doubling of carbon dioxide concentration, as simulated by the MSPDD biogeography model.

Aquatic environments Stream ecology Lake ecology The oceans Coasts Estuaries

24 Stream ecology Streams and rivers contain a minute portion of the world’s water (0.006%), but an enormous proportion of the fresh water that can be used by people. Consequently, they have been tapped, dammed, straightened, rerouted, dredged and polluted since the beginning of civilization.

25 Fig the species composition of stream invertebrate communities varies with conditions such as pH, summer temperature and waterflow.

26 Fig (b) the actual geographic distribution of community classes A-E in southern England.

27 Fig disturbances play an important role in stream ecology, particularly of stream insects.

28 Fig disturbances play an important role in stream ecology, particularly of stream insects.

29 Fig disturbances play an important role in stream ecology, particularly of stream insects.

30 Stream ecology The terrestrial vegetation surrounding a stream (the riparian vegetation) has two influences on the resources available to its inhabitants. –First, by shading ( 遮陰 ) the streambed it man reduce primary production. –Second, by shedding( 掉落 ) leaves it can contribute directly to the food supply of animals and microorganisms. (Fig. 4.16)

31 Fig Examples of the various categories of invertebrate consumers in stream environments. 撕碎 ( 或切碎 ) 者

32 Fig Examples of the various categories of invertebrate consumers in stream environments.

Topical ECOncerns A tiny stream fish with big consequences for property( 房地產 ) development The Cherokee darter (Etheostoma scotti) lives in clear streams with beds made up of pebbles and cobbles. Streambeds covered in silt deny this species the ability to forage and spawn; it is now restricted to just a few streams.

Lake ecology River ecology, the unidirectional flow of water. Lake ecology, the relatively stationary nature of water within its basin. –Epilimnion –Thermocline –Hypolimnion Fig Lakes at different positions in the landscape differ in the source of their water and the concentrations of chemicals important to their inhabitants. (a) Map of Wisconsin Lake district (b) Relationships between landscape position and concentrations of calcium and magnesium and silica in the five lakes.

35 Fig Lakes at different positions in the landscape differ in the source of their water and the concentrations of chemicals important to their inhabitants. (a) Map of Wisconsin Lake district

36 Fig Lakes at different positions in the landscape differ in the source of their water and the concentrations of chemicals important to their inhabitants. (a) Map of Wisconsin Lake district (b) Relationships between landscape position and concentrations of calcium and magnesium and silica in the five lakes.

the oceans The oceans cover the major part of the Earth’s surface and receive most of the Earth’s income of solar radiation. Euphotic zone (100m upper) –Below the euphotic zone is increasing darkness. ( 深海生態體系 ) The areas of greater marine productivity (> 90gC/m2/y) occur where there is a reliable supply of minerals (especially nitrogen and phosphorus, and perhaps iron).

coasts Marine environments change dramatically near to coasts. –Not only are they enriched by nutrients from the land; they are also affected by waves and tides that bring new physical forces to bear. Fig a general zonation scheme for the seashore determined by relative lengths of exposure to the air and the action of waves.

39 Fig. 4.18

40 Questions 1.Why is much of the open ocean, in effect, a ‘marine desert’? 2.Describe how the logging of a forest may influence the community of organisms inhabiting a stream running through the affected area. 3.The tropical rain forest is a diverse community supported by a nutrient-poor soil. Why?

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