Chapter 6: Carrying Capacity and Energy

 

The animal needs two basic things, in order to live: energy and protein. And this energy and protein it must be able to eat, to digest, and to metabolize, that is, change into other substances.

 

Where is the bison still able to live? Where will it find enough to eat, and where not? How much aboveground dry plant-matter must grow there at least per year? Where is the bison still able to graze? What is the lowest amount of aboveground dry plant-matter, where it will still find some food? And how much aboveground dry plant-matter must grow, so that the bison is able to live there, to maintain its body weight and to grow?

 

Where is the elephant still able to live? Where will it find enough to eat, and where not? How much aboveground plant-matter must grow there at least? How much food (energy) do the young and the adult elephant need? And now much energy does the young and the adult elephant cow, when she has a calf? Would they find enough to eat in an arctic or subarctic climate?

 

African mammals and plant mass

 

David Western reports in “Linking the ecology of past and present mammal communities” about African Mammals, how much they weigh and how much aboveground vegetation must grow there, so that they will be able to maintain their body weight and to grow properly. In Fossils in the Making, Anna K. Behrensmeyer and Andrew P. Hill (editors), The University of Chicago Press, Chicago, London 1980. This is the aboveground plant mass (dry weight), on which the animal feeds, like grasses, sedges, terminal twigs, leaves, and so on That is, the annual aboveground plant production and the vegetation, left over from the year(s) before that, which it is still able to eat.. It does not include the wood of the trees and bushes and “dead” plant mass, too low in protein, and too high in fiber.

 

 

 
Animal body weight and plant mass in Africa

 

Hoofed animal

Body weight (kg)

Average plant mass on which it feeds (g/mē) (dry wt)*

African elephant Loxodonta africana (Blumenbach)

2575

525

African buffalo Syncerus caffer (Sparman)

450

120

Zebra Equus burchelli (Gray)

200

79

Wildebeest Connochaetes taurinus (Burchell)

165

61

Grant’s gazelle Gazella granti (Brooke)

40

57

Impala Aepycerus melampus (Lichenstein)

40

51

Thomson’s gazelle Gazella thomsoni (Guntter)

15

44

 

After David Western (1980:51), Chart Figure 3.4. Relationship of an animal’s body weight to the average vegetation mass (dry weight), on which it feeds. Data from the Amboseli ecosystem (Western, D. 1973). * This is the aboveground plant mass (dry weight), on which the animal feeds, like grasses, sedges, terminal twigs, leaves, and so on That is, the annual aboveground plant production and the vegetation, left over from the year(s) before that, which it is still able to eat.. It does not include the wood of the trees and bushes, nor the “dead” plant mass of old grasses, too low in protein, and too high in fiber.

 

This means:

 

·     The African elephant weighing 2575 kg, needs an average plant mass or plant-cover, on which it feeds of 525 g DM/mē (dry weight).

 

 

 

Carrying capacity and energy

 

We shall investigate here only the energy, which it needs, in order to grow and to maintain its body weight. But this energy (dry plant-matter), the animal will only be able to use, that is, to eat, digest, and metabolize it, if it contains enough protein. The elephant in Africa, for example, will starve to death in a grassland, 1 to 2 meters high, if it contains too little protein.

 

During the Late Pleistocene, when the woolly mammoth was living in Yukon/Alaska, and Northern Siberia, the climate has been very dry. The northern part of Eurasia – from Western Europe to Eastern Siberia, and still further east, Alaska, and the Yukon Territory – where not buried beneath glaciers – were covered by a dry zonal arctic steppe, the experts say. Would the bison and the mammoth have found up there then enough to eat? Could they have lived on such an arctic dry steppe?

 

The azonal dry steppe on the south-facing slopes in the Yukon Territory, Alaska, and northeastern Siberia are supposed to show us, what this Mammoth Steppe in the Far North has been like, when the bison and the mammoth were grazing up there. Today, the re-introduced bison in Alaska and the Yukon Territory is only able to live at a few suitable places: where there is enough grass. In the other parts of Alaska and the Yukon, the bison is not able to live now, because it would starve there today.

 

Before re-introducing the rare Wood bison into the Yukon Territory, scientists like H. W. Reynolds of the Canadian Wildlife Service, have first studied all the places in the Yukon, where the bison might be able to live. They found out: The only place, where the bison is able to live now, is in the southwestern part of the Yukon Territory, in the rain-shadow of the mighty Coast Range. That is, in the area of the Nisling River Valley. And even there, it is able to use only a small part of its range: where enough grasses and sedges are growing.

 

In their research report, Range assessment of the Nisling River Valley, Yukon Territory as habitat for bison, May 1982 H. W. Reynolds and co-workers state, how large annual precipitation is now in the southwestern part of the Yukon Territory, in the Nisling River Valley: Total precipitation for the Aishihik (Airport) weather station in the southwestern Yukon, from 1941 to 1970: 243 mm.

 

How large was annual precipitation in the Polar Regions during the Late Pleistocene, when the bison and the mammoth were grazing in the Far North? What have scientists found out about this?

 

Thomas J. Crowley and Gerald R. North state in their book, Paleoclimatology (1991:53) under the heading “Precipitation Changes”: “With a few exceptions much of the planet seems to have been drier during the last ice age. Precipitation patterns varied by latitude belt. In high latitudes, accumulation rates in Greenland and Antarctic ice cores suggest that precipitation decreased about 50% in polar regions (Beer et al., 1985; Herron and Langway, 1985; Lorius et al., 1985).

 

This agrees with what other researchers have found out. And this means: When annual precipitation in Yukon, Alaska, and northern Siberia was only half as large, as it is now, annual aboveground plant-production has also been only half as large as it is now, if not even less. Because the plants will only begin to grow, if the ground is wet enough.

 

 

Southwestern Yukon Territory: dry loess steppe

 

How much fodder is growing now in the Yukon Territory, where the bison, the domestic cattle, and the horse are able to find something to eat? And how large is there the area for one animal unit per year (AUY)?

 

R. Johansen, Agriculture Branch, Department of Renewable Resources, in Whitehorse, Yukon, and co-workers, report in their “Grazing potential for selected areas in the Greater Kluane Planning Region” (1989:7, 11):

 

(1) Open aspen parkland, with the steppe grass Festuca altaica:

Forage production: 100 kg/ha = 10 g/mē.

Grazing capacity: 54.5 ha/AUY (animal unit per year).

They conclude: “There is little ground cover, which is palatable to domestic livestock, and therefore, the forage potential of this community is limited.”

 

(2) Alpine tundra, with grasses and sedges:

Forage production 100 kg/ha = 10 g/mē

Grazing capacity: 54 ha/AUY.

 

This means: Where only about 10 grams of aboveground dry plant matter have grown per square meter per year, or less, the bison, cattle, and horse will not find enough to eat anymore. Because they will use more energy, to take in this food, than they will gain from it. If these animals tried to live there on this fodder, they would need 54 hectares per animal unit per year.

 

 

Bison Pasture in Southern Canada

 

How much aboveground fodder must grow at least, so that the bison will be able to live there, to maintain its body weight, and to grow? What is its lower limit? And how much pasture would the bison then need in the subarctic climate of the southern Yukon Territory?

 

Lorne Klein is a Canadian expert on the nutrition of the bison and bison ranching in Southern Canada. He states in his research report, Bison pastures and grazing management (1989:3): “To meet forage quantity requirements, a pasture sward height of not less than four inches is recommended. Another measure is to graze only, where there is more than 300 lbs/acre of dry matter. This equals a height of about four inches, but will vary with plant density.”

 

300 lbs/acre is 136.1 g DM/mē year.

 

This means, the bison is still able to live, where at least 136.1 grams of aboveground plant matter (dry weight) have grown there per square meter per year. Only then will be bison be able, to maintain there its body weight and to grow. That is the lower limit.

 

The elephant is still able to live in East Africa, where 250 g DM/mē have grown per year from 300 mm of rain. That is the lower limit. Because, when only 200 g DM/mē have grown there, the elephant will starve to death.

 

 

 

Would the Mammoth now be able, to live in the Yukon and in Alaska?

 

 

Woolly mammoth. Engraving in the Cave of Les Combarelles, Dordogne, S.W. France. From: H.-G. Bandi (1952:50). Note, please, the mouth-like opening of its trunk: its upper and lower flap, used for grazing. The mammoth has lived in a mild, temperate climate, on a forest-steppe, together with other hoofed animals and rodents, adapted to the steppe and forest-steppe.

 

 

The bison and the mammoth are supposed to have lived in the Yukon and Alaska on a Mammoth Steppe, also during the height of the Last Ice Age, when it was there very dry, when it was extremely dry (R. D. Guthrie 2001). The azonal dry steppe on the south-facing slopes and the dry loess-steppe in the southwestern Yukon, at Kluane Lake, are supposed to show us, what this Mammoth Steppe has been like, how much fodder has grown there.

 

This is the Artemisia-Festuca community, in its grassland phase. That is, before the aspen trees begin to invade it. How much fodder is growing now on this azonal dry steppe? And how much pasture does one animal unit need there now per year (AUY)?

 

R. Johansen, Agriculture Branch, Department of Renewable Resources, in Whitehorse, Yukon, and co-workers, report in their “Grazing potential for selected areas in the Greater Kluane Planning Region” (1989:5):

 

Artemisia-Festuca (grassland/parkland complex): Grassland phase.

 

Forage production: 370 kg/ha = 37 g/mē

Grazing capacity:     15 ha/AUY

 

This means: On the azonal dry steppe, which is supposed to be most similar to the Mammoth Steppe of the Late Pleistocene, only 37 grams aboveground plant matter (dry weight) are growing per year. And 1 animal unit (450 kg bison, cow, horse) needs there 15 hectares per year.

 

The bison is only able to live, to maintain its body weight, and to grow, where at least 136 g DM/mē have grown per year. As a lower limit.

 

At 37 g DM/mē year, one animal unit needs in the dry southwestern Yukon now 15 hectares of pasture per year.

 

At 136 g DM/mē it needs then 3.676 ha/AUY: Lower limit of annual aboveground plant production for the bison, for maintenance and growth.

 

This means: the bison, as an animal unit of 450 kg body weight, needs in the dry subarctic climate of the southwestern Yukon now 3.67 hectares of this dry steppe or loess steppe, while 136 g DM/mē is growing there per year. Only then, and only there would it be able to maintain its body weight, and to grow. That is, when this food contains enough digestible crude protein. We should remember here: the elephant (and other large hoofed animals) in Africa will starve to death in a grassland, 1 to 2 meters tall, if it contains too little protein. Because they are not able then anymore, to digest it.

 

This also means: On the azonal dry steppe on the south-facing slopes, and on the dry loess-steppe of the southwestern Yukon, not even the bison would be able to live now. That is, it would not be able to maintain there its body weight and to grow. It would starve there to death.

 

Would the mammoth be able, to live now on the azonal dry steppe, growing on the south-facing steppe slopes and dry basins of the Yukon, Alaska, and Northeastern Siberia? How much energy does this elephant need, when young, when old, and when raising a calf? What have scientists found out now about this?

 

 

African Buffalo and Elephant, and their Animal Units

 

H.H. Meissner, Animal and Dairy Science Research Institute, Irene, Republic of South Africa, is one of the world’s leading experts on animal nutrition, also of the elephant. He has published his research report “Theory and application of a method to calculate forage intake of wild southern African ungulates for purposes of estimating carrying capacity” in S. Afr. J. Wildl. Res. 1982, 12: 41-47.

 

He, and his team of researchers write: When trying to find out, how many animals are able to live in a certain area, it is not enough, just to know their biomass. Animals of the same kind need different amounts of energy. The cow, raising a calf, for example, needs more energy, than the cow, which does not raise a calf. For the term animal unit (AU = animal unit), he uses LU (livestock unit): How much is that in his research?

 

A LU (livestock unit) is the equivalent of a steer with a mass of 450 kg, which has a growth rate of 500 g per day on grass pasture, with a mean digestible energy (DE) concentration of 55%. (To maintain this, 75 MJ ME per day is required.)

 

DE = digestible energy. ME = metabolizable energy, changing it into other forms. MJ ME = Mega Joule metabolizable energy. Mega = million.

 

I shall quote here briefly a few figures about the African buffalo and the South African elephant from his table “LU equivalents of wild ungulates and some other species” (1992:46):

 

African Buffalo

 

Class

Mass (kg)

ME (MJ/day)

LU (AU)

Calf, 8 months

145

31.8

0.424

Cow, dry, 4 years

460

79.1

1.055

Cow, dry, 10 years

530

76.4

1.019

Cow, with calf, 4 years

460

101

1.347

Cow, with calf, 10 years

530

99.3

1.324

Bull, 4 years

500

89.6

1.195

Bull, 10 years

640

87.7

1.169

 

From H. H. Meissner (1982:46). LU equivalents of wild ungulates and some other species, in S.-Afr. J. Wildl. Res. 1982:46.

 

This means, for example: The young dry African buffalo cow, 4 years old, weighs 460 kg. She needs 79.1 mega Joule metabolizable energy per day. And she represents an animal unit (LU or AU) of 1.055. One animal unit is here 450 kg. One animal unit (1 African buffalo, 450 kg) needs a usable plant mass of 120 g DM/mē (David Western 1980:44, 51, Fig. 3.4). The young African buffalo cow, 4 years old, with a calf, weighs 460 kg. She needs now 101 mega Joule metabolizable energy per day. She represents now 1.347 animal units.

 

 

African buffalo and North American Bison: Plant mass needed (g DM/mē)

 

Class

Mass (kg)

ME (MJ/day)

LU (AU)

Plant mass (g/mē)

Cow, with calf 4 years

460

101

1.347

161.4

Bull, 10 years

640

87.7

1.169

140.3

Bull, 10 years

800

109.6

1.461

175.3

Bull, 10 years

1000

137.0

1.826

219.1

Bull, 10 years

1200

187.5

2.192

263.0

 

1 animal unit (AU) or livestock unit (LU) is here for the African buffalo 450 kg. He needs a plant mass of 120 g/mē (David Western 1980:44, 51, Fig. 3.4). Based on H. H. Meissner (1982:46). LU equivalents of wild ungulates and some other species, in S.-Afr. J. Wildl. Res. 1982:46, Appendix.

 

This means: The African buffalo and the North American and European bison are only able to live, that is, to maintain their body weight and to grow properly, when there is the following amount of usable plant mass. That is, living aboveground vegetation, which the animal is able to digest:

 

The cow, with a calf, 4 years old, weighing 460 kg, needs 101 mega Joule metabolizable energy per day. She represents 1.347 livestock units (LU) or animal units (AU) per 450 kg. She needs a plant-cover of at least 161.4 g DM/mē.

 

The bull, 10 years old, weighing 640 kg, needs 87.7 mega Joule metabolizable energy. He represents 1.169 animal units. He needs a plant-cover with at least 140.3 g DM/mē.

 

The bull, 10 years old, weighing 800 kg, needs a plant mass of at least 175.3 g DM/mē.

The bull, 10 years old, weighing 1000 kg, needs a plant-mass of at least 219.1 g DM/mē.

The bull, 10 years old, weighing 1200 kg, needs a plant-mass of at least 263.0 g DM/ē.

 

This is based on the usable plant-mass, which the African buffalo needs, of 120 g DM/mē, to maintain its body weight and to grow properly. The South Canadian bison needs a plant-cover of at least 136.1 g DM/mē. That is 16.1 g DM/mē or 13.333 % more. Why does it differ? Why does the Canadian bison need more fodder than the African buffalo?

There may be several reasons: In Canada it is much colder than in Africa. The bison must grow there a thick winter coat; the African buffalo does not. And the bison must put on a thick layer of fat, to survive the next winter, the African buffalo does not, unless he must survive a nutritionally lean season. All this costs more energy and more protein, that is, more food. So, these values are still on the low side, when applied to the bison. In other words: this shows us, where the African buffalo and the North American and European bison, in their different stages of life, are able to live: How much usable aboveground vegetation must be there.

 

 

African Elephant

 

Class

Mass (kg)

ME (MJ/day)

LU (AU)

Calf, 5 years

850

84.8

1.131

Cow, dry, 15 years

1850

285

3.800

Cow, dry, 50 years

3300

291

3.880

Cow, with calf, 15 years

1850

362

4.287

Cow, with calf, 50 years

3300

375

5.000

Bull, 15 years

2200

303

4.040

Bull, 50 years

3700

310

4.133

 

From H. H. Meissner (1982:46). LU equivalents of wild ungulates and some other species, in S.-Afr. J. Wildl. Res. 1982:46.

 

This means, for example: The young elephant cow, 15 years old, dry (without a calf) weighs 1850 kg. She needs 285 Mega Joule metabolizable energy per day. She needs the energy of 3.8 livestock units (LU) or of 3.8 animal units (AU) per day, weighing 450 kg each.

 

The young elephant cow, 15 years old, with a calf, weighs 3300 kg. She needs now 362 Mega Joule metabolizable energy per day. And the energy, which she needs now, represents 4.287 livestock units (or animal units) weighing 450 kg each.

 

 

African Elephant and Northern Mammoth: Plant mass needed (g DM/mē)

 

Class

Mass (kg)

ME (MJ/day)

LU (AU)

Plant mass (g/mē)

Cow, with calf, 50 years

3300

375

5.000

600.0

Bull, 50 years

3700

310

4.133

496.0

Bull, 50 years

5000

419.0

5.585

670.2

Bull, 50 years

7500

628.3

8.377

1005.2

Bull, 50 years

10.000

837.3

11.170

1340.4

 

David Western (1980:44, 51) Chart Fig. 3.4 found out: The average African elephant weighs 2575 kg. And it needs an average plant mass, on which it feeds, of 525 g/mē. One animal unit, 1 African buffalo, weighing 450 kg, needs an average plant mass of 120 g DM/mē.

 

This means, as an example: The elephant cow, with calf, 50 years old, weighs 3300 kg. She needs then 375 mega Joule metabolizable energy per day, to maintain her body weight, to grow a little, and to feed her calf. She represents then 5.000 animal units. She needs then a usable plant-mass of 600.0 g/mē. How calculated: 120 g DM/mē, for 1 animal unit (1 African buffalo, weighing 450 kg) x 5.000 animal units (AU) or livestock units (LU) = 600.0 g/mē.

 

The elephant bull, 50years old, weighing 3700 kg, needs an average living plant mass or plant-cover, on which it feeds, of 496.0 g/mē (dry weight).

The elephant bull, 50 years old, weighing 5000 kg, needs an average living plant mass or plant-cover, on which it feeds, of 670.2 g/mē (dry weight).

The elephant bull, 50 years old, weighing 7500 kg, needs an average living plant mass or plant-cover, on which it feeds, of 1005.2 g/mē (dry weight).

The elephant bull, 50 years old, weighing 10,000 kg, needs an average living plant mass or plant-cover, on which it feeds, of 1340.4 g/mē (dry weight).

 

 

Mammoth on subarctic dry steppe

 

How would the mammoth fare now on the azonal dry steppe on the south-facing steep slopes of the Yukon, Alaska, and northeastern Siberia? Would this elephant find there enough to eat? Would the mammoth have found on this extremely dry Mammoth Steppe enough to eat, if it had been as dry as some of the world’s leading ice age and mammoth experts claim?

 

Let us find out first, how the elephant, in its different stages of life, would have fared on the dry grassland in the Kluane Lake Area, in the southwestern Yukon, where they have introduced now the rare Wood bison.

 

This dry steppe and loess-steppe in the southwestern Yukon produces now 37 g DM/mē per year (in its grassland phase). Grazing capacity: 15 ha/AUY. R. Johansen et al. (1989:5). The bison is only able to live, to maintain its body weight and to grow, where at least 136 g DM/mē has grown per year. On this azonal dry steppe in the southwestern Yukon it would need then 3.676 hectares per animal unit per year (ha/AUY). Let us look now at the following examples:

  

 

Bison cow with calf later in summer. Week by week, the calf is getting growing now larger and heavier. From: Grzimeks Enzyklopädie (1988:400) Vol. 5.

 

 

Example 1: Elephant calf, 5 years

 

Elephant calf, 5 years old, 850 kg body weight. It needs 84.8 Mega Joule metabolizable energy, for maintenance and growth. This represents 1.131 animal units (450 kg).

 

The bison needs in the southwestern Yukon at least 3.676 ha pasture, when 136 g DM/mē is growing there per year, so that it will be able to maintain its body weight and to grow. That is, if this fodder contains enough protein. In other words, where the bison is living, there should be an aboveground dry matter of at least 136 g DM/mē per year, as a lower limit.

 

The elephant calf, 5 years old, weighing 850 kg, needs the energy of 1.131 animal units.

3.676 ha/AUY (for bison) : 1.131 AU (for elephant calf) = 3.250 ha/AUY.

136 g DM/mē yr x 1.131 = 153.8 g DM/mē yr.

 

 

Example 2. Dry elephant cow, 15 years

 

Elephant cow, dry, 15 years, 1850 kg body weight. She needs 285 MJ metablizable energy per day for maintenance and growth. And she needs then the energy of 3.800 animal units, weighing 450 kg each.

 

The bison needs in the southwestern Yukon at least 3.676 ha, when 136 g DM/mē is growing there per year, so that it will be able to maintain its body weight and to grow. That is, if this fodder contains enough protein.

 

The dry elephant cow, 15 years old, weighing 1850 kg, needs the energy of 3.8 animal units.

3.676 ha/AUY (for bison) : 3.8 (for elephant dry elephant cow) = 0.967 ha/AUY.

136 g DM/mē yr (for bison, 1 animal unit) x 3.8 = 516.8 g DM/mē yr.

 

This means, this dry elephant cow would only by able to live on this azonal dry steppe and loess-steppe of the southwestern Yukon, it would only find there enough metabolizable energy, if 516.8 g DM/mē, or, rounded up, 517 g DM/mē yr were growing there. She would need then a pasture of 0.967 hectares per year.

 

But during the Late Pleistocene, when the mammoth and bison were grazing up there, annual precipitation was supposed to have been only about half as large as it is now. Hence, the southwestern Yukon would have had then only 121 mm precipitation per year. And annual aboveground plant production would also have been then only half as large as it is now. So instead of the 37 g DM/mē, the azonal dry steppe and loess-steppe of the southwestern Yukon would have grown then only 18.5 g DM/mē per year.

 

We should remember her: The East African elephant will starve to death, where only 200 g DM/mē has grown per year. And the bison needs about 136 g DM/mē for maintenance and growth. So, neither the bison nor the mammoth could have lived on this Mammoth Steppe. They would have starved to death.

 

Today, 37 g DM/mē is growing on this dry steppe in the southwestern Yukon at 243 mm precipitation per year. That is 0.1522633745 g DM/mē per millimeter of rain per year.

 

The elephant needs at least 250 g DM/mē. 250 g DM/mē : 0.1522633745 g DM.mē/mm precipitation per year = 1642 mm precipitation per year.

 

This means: The elephant is only able to live, where at least 250 g DM/mē has grown per year. And this 250 g DM/mē will only be able to grow now on the dry slopes of the southwestern Yukon, if there were 1642 mm precipitation per year! There is now way around this.

 

 

Example 3: Elephant cow, with calf, 15 years

 

The elephant cow, with a calf, 15 years old, weighs 1850 kg. She needs 362 Mega Joule metabolizable energy per day. And the energy, which she needs per day, represents 4.827 animal units weighing 450 kg each. How would she fare on the azonal dry steppe on the steep south-facing slopes, on the azonal dry loess steppe, said to be very similar to the extinct Mammoth Steppe?

 

The bison needs in the southwestern Yukon at least 3.676 ha pasture, when 136 g DM/mē is growing there per year, so that it will be able to maintain its body weight and to grow. That is, if this fodder contains enough protein.

The elephant cow, 15 years old, weighing 1850 kg, with a calf, needs the energy of 4.827 animal units.

3.676 ha/AUY (for bison = 1 animal unit 450 kg) : 4.827 (for young 15 year-old elephant cow, with calf) = 0.761 ha/AUY.

136 g DM/mē yr x 4.827 = 656.5 g DM/mē yr.

 

This means: This 15-year-old elephant cow, with a calf, will only be able to live on the azonal dry loess-steppe of the southwestern Yukon, if there grew 656.5 g DM/mē per year. She needs then a pasture of 0.761 ha/AUY.

 

And then: This fodder of 656.5 g DM/mē would only able to grow now in the dry subarctic climate of the southwestern Yukon, if there were an annual precipitation of 4312 mm per year (How calculated: 656.5 g DM/mē yr : 0.152263374 g DM/mē/mm annual precipitation).

 

 

Example 4: Elephant cow, dry, 50 years old

 

The elephant cow, dry, 50 years old, weighs 3300 kg. She needs 291 Mega Joule metabolizable energy per day. The energy, which she needs per day, represents 3.880 animal units, weighing 450 kg each.

 

The bison needs in the southwestern Yukon at least 3.676 ha pasture, when 136 g DM/mē is growing there per year, so that it will be able to maintain its body weight and to grow. That is, if this fodder contains enough protein.

 

The elephant cow, dry, 50 years old, weighs 1850 kg. She needs the energy of 3.880 animal units.

3.676 ha/AUY (for bison = 1 animal unit, 450 kg) : 3.880 (for dry, 50-year-old elephant cow) = 0.947 ha/AUY.

136 g DM/mē yr (for bison) x 3.880 = 527.7 g DM/mē yr.

 

This means: The 50-year-old dry elephant cow, weighing 3300 kg, would only be able to live on the subarctic dry loess-steppe of the southwestern Yukon, if 527 g DM/mē were growing there per year, instead of only 37 g DM/mē like now. She needs then 0.947 ha per year.

 

 

Example 5: Elephant cow, with calf, 50 years old

 

The elephant cow, 50 years old, with a calf, weighs 3300 kg. She needs 375 Mega Joule metabolizable (changeable) energy per day. That represents 5.000 animal units weighing 450 kg each.

 

3.676 ha/AUY (for bison) : 5.000 (for 50-year-old elephant cow, with calf) = 0.735 ha/AUY.

136 g DM/mē yr (for bison = 1 animal unit, 450 kg) x 5.000 = 680 g DM/mē yr.

 

This means, the 50-year-old elephant cow, with a calf, weighs 3300 kg. She will only be able to live on the dry loess-steppe of the southwestern Yukon, if 680 g DM/mē were growing up there per year. She would need then 0.735 hectares of pasture per year. In an arctic climate this is not possible.

 

 

Example 6: Elephant bull, 15 years old

 

The South African elephant bull, 15 years old, weighs 2200 kg. He needs 303 Mega Joule metabolizable energy per day. That represents 4.040 animal units weighing 450 kg each.

 

3.676 ha/AUY (for bison) : 4.040 (for 15-year-old elephant bull) = 0.910 ha/AUY.

136 g DM/mē yr (for bison) x 4.040 = 549.4 g DM/mē yr.

 

This means: The young elephant bull, 15 years old, weighs 2200 kg. He would only be able to live on the dry steppe of the southwestern Yukon, if at least 549.4 g DM/mē per growing up there per year. In an arctic climate this is not possible.

 

 

Example 7: Elephant bull, 50 years old

 

The elephant bull, 50 years old, weighs 3700 kg. He needs 310 Mega Joule metabolizable energy per day. That represents 4.133 animal units.

 

3.676 ha/AUY (for bison) : 4.133 (for 50-year-old elephant bull) = 0.889 ha/AUY.

136 g DM/mē yr (for bison) x 4.133 = 562.1 g DM/mē yr.

 

This means: the 50-year-old elephant bull, weighing 3700 kg, will only be able to live in the subarctic dry steppe of the southwestern Yukon, if at least 562.1 gDM/mē were growing there. He would need then 0.889 hectares of range. In an arctic and subarctic climate this is not possible. Too little fodder is growing there. We should remember here: This growth of annual aboveground dry matter will only be able to feed the elephant and the bison, if it contains enough protein, especially during the long months of the arctic winter.

 

 

Elephant: aboveground dry matter and carrying capacity

 

Class

Mass (kg)

ME (MJ/day

LU (AU)

g DM/mē.yr

ha/AUY

Calf, 5 years

850

84.8

1.131

153.8

3.25

Cow, dry, 15 years

1850

285

3.800

517

0.967

Cow, dry, 50 years

3300

291

3.880

656.5

0.761

Cow, with calf, 15 years

1850

362

4.287

680

0.735

Cow, with calf, 50 years

3300

375

5.000

549.4

0.910

Bull, 15 years

2200

303

4.040

562.1

0.889

 

From H. H. Meissner (1982:46). LU (AU) equivalents of wild ungulates and some other species, in S.-Afr. J. Wildl. Res. 1982:46. I have added in this table the amount of aboveground dry matter, per square meter per year (g DM/mē.yr), which must grow per year for each class of elephant, in its different stages of life. And how much pasture it needs then, in hectares per animal unit per year (ha/AUY), (carrying capacity).

 

As an example: The elephant cow, with calf, 15 years, is only able to live, where there is an aboveground plant-production (dry weight) of 680 grams per square meter per year. And she needs then a pasture of 0.735 hectares per year. But this fodder must contain enough digestible crude protein. Otherwise the elephant will starve there with a full stomach, due to lack of protein. In Africa, elephants and other large grazers will starve to death in a grassland, 1-2 meters high, if this grass contains to many fibers and too little protein. They will not be able to digest it then anymore and starve to death with a full stomach.