Energy Flow

Energy Flowing Through the Ecosystem

After four and a half billion years of inter-dependencies, 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 Hotspots


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

See 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., Nature 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.