Energy Flowing Through the Ecosystem

Chapters:

  1. Ecosystems
  2. Consumption
  3. Population
  4. Trophic Pyramid

Tables:

Figures:


1. Ecosystems

After four and a half billion years of interdependencies, the life on Earth is a complex ecological system or ecosystem. As it turns out, some physical parameters make for greater quantities of life. A tropical rain forest is a good example. Other locations are almost barren of life, such as the Antarctic.

Biodiversity is a word that conveys the richness of the disparity of life. Land with many species and specimens has a high biodiversity. This occurs where energy is abundant and is readily mobile. Estuaries, tree tops and swamps have high biodiversity. Where there is little energy or little capacity to move energy about, there are few species and specimens.

Humans have usurped land with the richest supplies of energy. In so doing, they have removed the indigenous flora and fauna. This removal of the competition is a step in the direction of a future that allows only for life that provides a benefit to people. The following map provides and indication of our influence. It shows biodiversity hot spots; the richest and most threatened areas of the world.

Figure 1. Biodiversity Hot spots

Plans for the future can use land characteristics to determine energy levels. Associating ecosystems with land cover and with energy deposition can provide and indication of the amount of energy that is available and can be sustainably appropriated. The following map and table give and indication of our current knowledge.

Figure 2. Global Land Cover Characteristics From AVHRR

Table 1. Percentage Global Land Cover Characteristics From AVHRR

Id

Region

Area sq.m.

Cell count

percent

17

Antarctica

12955294896358.210938

975792

9.64%

20

Major Woods-Main Taiga

15571041627.412062

414

0.00%

21

Major Woods-Main Taiga

5538192477539.941406

139371

1.38%

22

Major Woods-Other Conifer

3102704024062.733887

60725

0.60%

23

Major Woods-Mixed: Decid & Evergrn Broad Lf with conifer

1536950883557.831299

31763

0.31%

24

Major Woods-Mixed: Decid & Evergrn Broad Lf with conifer

2007185848676.121094

30340

0.30%

25

Major Woods-Temp Broad Lf Forest

780287115971.479248

14759

0.15%

26

Major Woods-Temp Broad Lf Forest

712378712833.701538

11636

0.11%

27

Major Woods-Other Conifer

402802513310.048279

6546

0.06%

28

Interrupted Woods-Trop Montain:frst,grass,scrub,paramo,rock

1185786717748.041992

15459

0.15%

29

Major Woods-Trop/Subtrop Broad Lf Humid frst

6162632446114.984375

79817

0.79%

30

Non Woods-Cool/Cold Farms/Towns

2959862698549.866699

57507

0.57%

31

Non Woods-Warm/Hot Farms/Towns

9309647348894.322266

143007

1.41%

32

Major Woods-Trop/Subtrop Dry frst and Woodld

4714611523027.708984

61804

0.61%

33

Major Woods-Trop/Subtrop Broad Lf Humid frst

4250460429679.579102

54125

0.53%

36

Non Woods-Irrigated Paddylnd

1987885037439.005859

27453

0.27%

37

Non Woods-Other Irrigated Drylnd

1204215951987.350586

17621

0.17%

38

Non Woods-Other Irrigated Drylnd

284208608067.502075

4880

0.05%

39

Non Woods-Other Irrigated Drylnd

84052062887.436249

2007

0.02%

40

Non Woods-Main Cool Scrub & Grassld

3943879596164.254883

74347

0.73%

41

Non Woods-Main Warm/Hot Scrub & Grassld

17281753920109.261719

249837

2.47%

42

Non Woods-Tibetan, Siberian Cold Grass/Stunted Wood Complex

844962972873.480713

16607

0.16%

43

Interrupted Woods-Trop Savanna & Woodld

6717216465060.143555

87037

0.86%

44

Wetld/Coastal-Major Bog/Mire, Cool/Cold Climates

974049034298.122925

22510

0.22%

45

Wetld/Coastal-Major Warm/Hot Mangrove/Tropical Swamp Forest

1567705039505.850830

21278

0.21%

46

Interrupted Dry Woods-Mediterranean types

1001897102499.186401

15630

0.15%

47

Interrupted Dry Woods-Other Dry & Highld wds

2594651830663.824707

38087

0.38%

48

Interrupted Dry Woods-Semiarid Woodld & Low Frst

907562417199.618164

12612

0.12%

49

Non Woods-Nonpolar Sparse (rocky) Vegetation

16583263310.775343

222

0.00%

50

Non Woods-Nonpolar Sand Desert

5224729037072.687500

75477

0.75%

51

Non Woods-Other Nonpolar Desert & Semidesert

10945523633729.777344

157360

1.55%

52

Non Woods-Nonpolar Cool Semidesert Scrub

2001583803636.694824

36217

0.36%

53

Non Woods-Tundra

9393530849909.560547

270103

2.67%

54

Non Woods-Tundra

63252319789.794365

1218

0.01%

55

Interrupted Woods-Trop/Temp wds, Fields, Grass, Scrub

1213730638498.606445

24058

0.24%

56

Interrupted Woods-2nd grow Trop/sub Trop, Humid/temp/boreal frst

2901879848728.266602

44004

0.43%

57

Interrupted Woods-2nd grow Trop/sub Trop, Humid/temp/boreal frst

2237122005999.954102

42824

0.42%

58

Interrupted Woods-Trop/Temp wds, Fields, Grass, Scrub

2862917892459.063965

41620

0.41%

59

Interrupted Dry Woods-Succulent & thorn

3960416798810.236328

52661

0.52%

60

Major Woods-Southern Taiga

1141925938973.127930

26045

0.26%

61

Major Woods-Southern Taiga

454631805719.985657

9375

0.09%

62

Interrupted Woods-North/Maritime Taiga, subalpine

4353694475333.803223

123731

1.22%

63

Non Woods-Wooded Tundra Cold Grass/Stunted Wood Complex

1755574562241.592285

48608

0.48%

64

Non Woods-Heath & Moorland

150965279690.782806

2842

0.03%

65

Wetld/Coastal-Shore and Hinterland Complexes

346743177268.794556

5576

0.06%

66

Wetld/Coastal-Shore and Hinterland Complexes

271643838092.094574

4012

0.04%

67

Wetld/Coastal-Shore and Hinterland Complexes

227736876864.228302

3687

0.04%

68

Wetld/Coastal-Shore and Hinterland Complexes

158688278350.119598

2498

0.02%

69

Non Woods-Polar or Rock Desert

537498290159.993896

33652

0.33%

70

Non Woods-Ice

2200308405065.088379

107593

1.06%

71

Non Woods-Other Nonpolar Desert & Semidesert

92485282559.789078

1463

0.01%

*

no data or ocean

362524045849111.750000

6737183

66.54%


Using simpler headings, the FAO appoint the land surface of Earth as follows. Values are in hectares as for 2005, database accessed 2009 February.

Table 3. Land Cover From FAO

Total area

13 432 420 000

Land area

13 013 475 400

Agricultural area

4 967 579 500

Arable and Permanent Crops

1 561 681 000

Arable land

1 421 169 100

Permanent Crops

140 511 700

Permanent Pasture

3 405 897 000

Forest and Woodland

3 952 025 700

All other land

4 092 972 400

Inland Water

429 928 000

UFZ - 2013

In order to assess the global impacts of land use on the environment and help provide appropriate countermeasures, a group of researchers under the leadership of the Helmholtz Centre for Environmental Research (UFZ) has created a new world map of land use systems. Based on various indicators of land-use intensity, climate, environmental and socio-economic conditions, they identified twelve global patterns called land system archetypes.

Click on map for greater definition.

2. Consumption

Once we've exhausted the fossil fuels, we'll need to find our energy from other sources. Vegetation lies at the base of the ecosystem and it can provide energy whether wood for fires or fruit for eating. Vegetation is also refereed to as net primary production or NPP.

The following maps give an idea of the degree of impact that we have on the land surfaces of Earth. Obviously any appropriation that is greater than the rate of replenishment is not sustainable. If we use 100% or more of the net primary production, then the vegetation can not replenish and it will perish. Thus, it cannot collect any more energy from the Sun for us to use. The sustainable level of appropriation is likely much less than 100%. Yet, from the first map, we see that huge swathes of the most productive land are having their energy stores directed to human usage.

Today, the energy source is mainly fossil fuels. However, once they are exhausted we will need get our energy from elsewhere. Vegetation will become the most likely source. These maps show that this future is unsustainable hence would not make a good plan. Alternatives aren't obvious.

Human appropriation of net primary production (NPP) as a percentage of the local NPP.

Figure 3: Human appropriation of net primary production

Global distribution of resource consumption as measured by the amount of net primary production (NPP) appropriated by humans.

Figure 4: Distribution of net primary production


The news is no better for the ocean resources as shown in the following depiction of change from 1966 to 2009 in use of primary production.

See Watson, et.al., Natuire Communications, accessed 2016.

3. Population

People need energy to power their bodies. This is biological energy. The more people that there are on Earth, the greater is their biological need. The following figure and table shows the increasing need based upon the standard 10 MJ energy per day requirement. This is about 3.65 x 109 Joules per year.

Figure 5: Humanity's Consumption of Energy

energy consumption

The graph shows the story, the numbers give structure to any planning.

Table 3: Humanity's Increasing Energy Consumption

Year

Population

Annual Energy Needs (x1010 MJ)

-10000

2

0.73

-8000

5

1.8

-6500

6

2.2

-5000

7

2.5

-4000

7

2.5

-3000

14

5.1

-2000

27

9.8

-1000

50

18

-500

100

36.5

-400

162

59.1

-200

200

73

1

250

91

200

250

91

400

200

73

500

200

73

600

200

73

700

205

75

800

220

80

900

230

84

1000

275

100

1100

305

111

1200

360

131

1250

400

146

1300

400

146

1340

443

162

1400

370

135

1500

450

164

1600

545

199

1650

500

182

1700

600

220

1750

700

250

1800

900

328

1850

1,200

438

1900

1,600

584

1950

2,500

912

2000

6,073

2216

2006

6,541

2387

Values found on the U.S Census Bureau;

4. The Trophic Pyramid

Energy is essential for life on Earth. It flows through levels of the ecosystem. However, the flow is not very efficient. Even after millions of years of genetic improvements, there's still only about a 10% transfer of energy from one level of the pyramid to a higher level. The shape of a pyramid highlights this poor transfer rate but also highlights the dependence of one level to its supporting level underneath. The trophic pyramid is fundamental to life and is a valuable relation when considering energy allocations in the future.

The ecosystem's trophic pyramid is shown below.

Figure 6: The Trophic Pyramid

Trophic Pyramid

At the base of the pyramid are the autotrophs. These living things capture their energy needs directly from the Sun. Most of the plants about us are autotrophs. People are not as people cannot convert the Sun's radiation into a form that would power their bodies.

The next step up the pyramid is allocated to the herbivores. These creatures, munch on the plants. In so doing they capture their energy needs from the energy stores within the plants. Some people are pure vegetarians. Because of this, they live at this level of the trophic pyramid. Given the efficiencies of energy conversion, herbivores capture only about 10% of the plants energy stores.

The next step up the pyramid is allocated to the carnivores. These creatures, eat other animals. Some special cases like people and bears eat both vegetation and other animals. This merits giving them the name omnivore. Again because of efficiencies, meat eaters capture only about 10% of the energy stores in the herbivores. But this represents 1% of the original energy in the plants. Given this poor energy transfer efficiency, it is no wonder that carnivores are greatly outnumbered by herbivores who themselves are greatly outnumber by vegetation.

Sitting at the top of the pyramid are the tertiary consumers. These creatures feed on the carnivores. This seems unrealistic as most people believe that carnivores and more specifically, themselves, are at the top of the pyramid. However, there are huge quantities of tiny little creatures that feast on any dead creature. These are called saprotrophs. These little critters eat the dead which still contain large quantities of energy. As well, these creatures release the chemicals of the body so that they can be used in other bodies. Again considering efficiencies, only 10% of the dead creature or about 0.1% of the originating plant's energy is captured by the saprotrophs, yet their usefulness is unquestionable.

We know the total amount of energy and energy transfer efficiencies. With these we can calculate the maximum possible number of creatures at each level of the pyramid. This calculation facilitates future planning.

by Mark Foster Mortimer