Chapter 7 Physical Environment Ayo Japalurahotmail com Chap

Chapter 7 Physical Environment 鄭先祐 生態主張者 Ayo Japalura@hotmail. com Chap 07 Physical environment

Road Map Physical environment • Physical variables commonly limit the abundance of plants and animals – Resources – Variables critical to survival • Physical factors commonly limiting species – – Extreme temperatures Wind Salt Global climate change • Physical environment limits abundance and distribution • Physical environment can alter species composition Chap 07 Physical environment 2

Physical Variables and Species Abundance • Liebig’s Law of the Minimum (1840) – The distribution of a species will be controlled by that environmental factor for which the organism has the narrowest range of tolerance – Optimum range (Figure 7. 1) – Effects of competition (Figure 7. 2) Chap 07 Physical environment 3

Population density Lowest limit of tolerance Highest limit of tolerance Physiological optimum Inability to survive Low tolerance Inability to survive Species absent Low population Species absent Physical gradient (e. g. , p. H) Fig. 7. 1 Organismal distribution along a physical gradient, such as p. H. Chap 07 Physical environment 4

Wavy hair grass Sheep’s fescue Relative species performance (Deschampsia flexuosa) 3 4 5 6 7 (Festuca ovina) 8 Small scabious 4 5 6 7 8 Common sorrel (Scabiousa columbaria) 3 3 (Rumex acetosa) 6 7 8 3 4 5 6 7 8 p. H at 2 cm depth Ecological optimum curve Chap 07 Physical environment Physiological optimum curve Fig. 7. 2 5

Physical Variables • Temperature – Affects biological processes – Organism’s inability to regulate body temperature • Distribution of Coral Reefs (Figure 7. 3) • Distribution of Larrea tridentata (Figure 7. 4) • Distribution of vampire bats (Figure 7. 5) Chap 07 Physical environment 6

30°N 20°C 30°S Fig. 7. 3 the world distribution of coral reefs closely matches the 20 o. C isotherm for the coldest month of the year(dashed line). Chap 07 Physical environment 7

Latitude 40 35 30 Minimum temperature Less than -16°C Less than -20°C 25 120 115 110 Longitude Chap 07 Physical environment 105 100 8

Fig 7. 5 the northern distribution of the vampire bat. 30° 20° Recent records Fossil records 10° Mean minimal temperature for January, 10°C 110° 100° Chap 07 Physical environment 90° 80° 9

Mean temperature vs. Extreme temperatures • Frequency of extremes limits species – Ex. Agriculture and occurrence of freezing temperatures • Distribution of oranges in Florida • Distribution of coffee in Brazil Chap 07 Physical environment 10

Correlations between temperature and species distribution – Temperature maps may not coincide with what organisms experience – Movement from sun to shade environments – Temperature at the local scale, is much more variable • Ex. Microclimates of a tree – South-facing vs. north-facing canopy – Soil surface to top of canopy • Ex. , Rufous grasshopper – Restricted to steep sunny slopes – Combination of time and temperature is important – Degree-days determine development Chap 07 Physical environment 11

High temperature • High temperatures denature proteins (temperatures above 45°) • Organisms effectively cool themselves through water loss • Life-history stages resistant to high temperatures – Resting spores of fungi – Cysts of nematodes – Seeds of plants • Ex. Dry wheat grains (90°) • Thermus aquaticus (67°) • Thermophilic bacteria (100°; Figure 7. 6) Chap 07 Physical environment 12

Fig. 7. 6 Thermophilic giant tubeworms growing at 8, 000 feet depth around deep sea vents in the Galapagos rift. Chap 07 Physical environment 13

Fire • North America before the arrival of Europeans – Fires started by lightening – Frequent and regular – Consumed leaf litter, branches and undergrowth before great quantities accumulated – Large trees usually not damaged – Some species evolved to require fire • Pinus banksiana • Pinus palustris • Serotinous cones • Cones sealed with resin • Require heat from fire to open Chap 07 Physical environment 14

• North America after the arrival of Europeans – Management practices • Maintain “natural” environment • Preventing forest fires • Produced the opposite – Change in species composition • Catastrophic fires (Figure 7. 7) Chap 07 Physical environment 15

Fig. 7. 7 (a) when fires burn in a natural cycle, the leaf litter does not have much time to accumulate and the fire burns with a moderate heat. Chap 07 Physical environment 16

Fig. 7. 7 (b) when fires are suppressed, much litter accumulates, and any fires that do ignite, quickly get out of control and burn high in the forest canopy, killing mature trees. Chap 07 Physical environment 17

Global warming • Two issues – Rate of global warming – Contribution by humans • Increased global warming = greenhouse effect – Atmosphere transmits short-wave solar radiation • 50% passes through the atmosphere unaltered to heat the earth. • Energy absorbed by the earth is radiated back to the atmosphere as long-wave radiation • Long-wave radiation, much is absorbed by clouds • A large amount of energy absorbed in the atmosphere is returned to the earth, causing the temperature to rise Chap 07 Physical environment 18

Earth requires some "greenhouse effect" • Without any greenhouse effect – Global average temperature: -17° • With greenhouse effect – Global average temperature: +15° • Explains hot Venus (blanketed in CO 2) and cold Mars (which has little atmosphere) Chap 07 Physical environment 19

Greenhouse gases Chap 07 Physical environment 20

340 Carbon dioxide 320 300 280 260 1750 1800 1850 1900 1950 2000 CH 4 concentration (ppmv) CO 2 concentration (ppmv) 360 1800 1000 600 1750 1800 1850 1900 290 1850 1900 1950 2000 CFC concentration (ppbv) N 2 O concentration (ppbv) Nitrous oxide Year 1950 2000 Year 300 280 1750 1800 Methane 1400 Year 310 Fig 7. 8 0. 3 Chlorofluorocarbon-11 0. 2 0. 1 0. 0 1750 1800 1850 1900 Chap 07 Physical environment Year 1950 2000 21

Influence of natural sources • Nitrous oxide – 2/3 comes from natural soils and oceans • Methane – 1/3 comes from bogs, swamps, and termites • Dust and carbon – Volcanoes Chap 07 Physical environment 22

Human influences • 75% of increases in CO 2 emisssions • 39% of methane output • 36% of nitrous oxide emissions • ~50% of all greenhouse emissions • Alterations in land use (~25%) – Deforestation – Conversion to rice paddies • Increase in domestic animals • Agricultural soils – Overall, humans account for 75% of the increase in greenhouse gases – Is it possible to replace fossil fuels? Chap 07 Physical environment 23

Evidence of temperature increases • Temperature record (Figure 7. 9) – Problems with record • Although the number of recording station may be large, their geographic distribution is not truly global. • Some stations may have experienced substantial warming due to changes in land use and population density– the “urban-heat-island effect”. Chap 07 Physical environment 24

0. 4 Change from 1940 temperature (°C) Fig. 7. 9 global surface temperature 0. 2 0. 0 -0. 2 -0. 4 -0. 6 1870 1890 1910 1930 Year Chap 07 Physical environment 1950 1970 1990 25

Computer models and predictions • Too many variables to include in a single computer model. • Negative feedback mechanisms • Positive feedback mechanisms • UN Intergovernmental Panel on Climate Change (IPCC) – 1996 report – Lack of fit of models • Emphasizes the complexity of interactions Chap 07 Physical environment 26

Environmental impact • Speed and extent of global warming • Focus on 2100 – Atmospheric CO 2 will have doubled – Temperature will have risen 1 to 3. 5° C Chap 07 Physical environment 27

Natural ecosystems • Profound changes in natural ecosystems • Most species cannot evolve significantly or rapidly enough to counter climate changes • Most species will not be able to disperse or migrate fast enough to keep up with climate change – Figure 7. 10 Chap 07 Physical environment 28

400 km Fig. 7. 10 The geographic range of sugar maple(blue shading)and its potentially suitable range under doubled CO 2 levels (yellow shading) in North America. Chap 07 Physical environment 29

Rainfall patterns • Increase in rainfall (Figure 7. 11) in most areas – Increase crop production – Ex. Tropical countries and rice production • Decrease in some areas already dry – Midcontinental America and Asia • More droughts • More extinctions • Current grain producing areas would become drier Chap 07 Physical environment 30

Fig. 7. 11 predicted changes in precipitation patterns caused by global warming. Chap 07 Physical environment 31

Wind • Can be caused by temperature gradients • Amplifies temperature effects on organisms – Increase heat loss through evaporation and convection – Increases animal evaporation and plant transpiration • Wind aids pollination • Wind disperses plant seeds • Affects mortality (Figure 7. 12) – High winds – Severe storms • Modify wave action Chap 07 Physical environment 32

Fig. 7. 12 This huge live oak tree was felled by strong winds in North Florida. Chap 07 Physical environment 33

Salt • Increases osmotic resistance to water uptake – Occurs in arid regions – Important to agriculture in arid regions • Increases salt concentration • Decreases crop yield – Salt marshes • Halophytes • Adapted to high salt concentrations • Ex. Spartina grasses (Figure 7. 13) Chap 07 Physical environment 34

Fig. 7. 13 special salt glands in Spartina leaves exude salt, enabling this grass to exist in saline inter-tidal conditions. Chap 07 Physical environment 35

p. H • Few organisms can exist below p. H 4. 5 – Ex. Lake trout in Eastern US disappear when p. H drops below 5. 2 • Roots are damaged below p. H 3 and above 9 – Calciphobe: only grow on acidic soils – Calciphiles: only grow in basic soils – Neutrophiles: tolerant of either condition Chap 07 Physical environment 36

Water • Protoplasm is 85 -90% water • Distribution of many plants limited by water availability • Animal distribution affected by desiccation • Tolerance and avoidance Chap 07 Physical environment 37

7. 2 Physical Factors and Species Abundance • Davidson, Andrewartha, and Birch – Thrips (Figure 7. 14 + Figure 7. 15) – Fed on rosebushes – Counted every 81 consecutive days – 78% of variation in population maxima was accounted for by weather – Predict the number of thrips using multiple regressions • Log y = -2. 39 + 0. 125 a + 0. 201 b + 0. 186 c +0. 085 d – – – Log y = log of thrip density a = winter temperature b = spring rainfall c = spring temperature d = size of overwinter population Chap 07 Physical environment 38

Observed Predicted Number of thrips per flower 600 400 200 0 1932 1934 1936 1938 1940 1942 1946 Fig. 7. 15 Comparison of means of observed annual population densities of thrips with densities predicted by a model. Chap 07 Physical environment 39

Rainfall • Africa Buffalo and environmental regulation – Rainfall and grass productivity in the Serengeti – Buffalo density regulated by food availability – Figure 7. 16 • Woddell, Mooney, and Hill (1969) – Correlation between rainfall and creosote bush density – Figure 7. 17 Chap 07 Physical environment 40

25 Lake Manyara gives permanent fresh water Number of buffalo per km 2 20 15 10 5 500 1000 Rainfall (mm) Chap 07 Physical environment 1500 Fig. 7. 16 2000 41

12 (30. 5) Rainfall ( in (cm) ) 10 (25. 4) 8 (20. 3) 6 (15. 2) 4 (10. 2) 2 (5. 1) • Fig. 7. 17 1 2 3 4 1000 2 ft (93 m 2) Chap 07 Density/ Physical environment 5 42

7. 3 Physical Factors and Numbers of Species • Importance of evapo-transpiration – Figure 7. 18 Chap 07 Physical environment 43

10 20 0 0 30 40 40 10 40 30 60 30 80 30 100 20 140 160 180 Fig. 7. 18 tree species richness in Canada and US. Contours connect points with the same approximate number of species per quadrant. Chap 07 Physical environment 44

Physical Factors and Numbers of Species • Robert Whittaker (1969) – Four hypotheses explaining distribution patterns – Figure 7. 19 • (1) competition caused sharp boundaries among distinct groups • (2) competition caused sharp boundaries between species • (3) physical variables cause distinct boundaries between groups. • (4) physical variable cause distinct boundaries between species. Chap 07 Physical environment 45

(1) competition caused sharp boundaries among distinct groups (2) competition caused sharp boundaries between species (3) physical variables cause distinct boundaries between groups. (4) physical variable cause distinct boundaries between species. Species abundance (1) (2) (3) (4) Fig. 7. 19 Environmental gradient Chap 07 Physical environment 46

Diseases and Global climate change • Spread of tropical diseases poleward – Controlled by the range of their vectors • Ex. Mosquitoes and other insects • Insects are ectotherms – Increase in temperature = increase in range and activity of vectors • Ex. Rwanda 1987 – 1° C increase in temperature resulted in a 337% increase in malaria Chap 07 Physical environment 47

Diseases likely to spread Chap 07 Physical environment 48

Computer model prediction • Average global temperature increase of 3° C – 50 -80 million new cases of malaria per year Chap 07 Physical environment 49

v 問題與討論！ Japalura@hotmail. com Ayo 台南站： http: //mail. nutn. edu. tw/~hycheng/ Chap 07 Physical environment 50