**5. Importance of deserts and semi-deserts regarding the whole biosphere and human society**

Global ecological importance of deserts and semi-deserts in the broader sense can be estimated according to their area and indicators of their vegetation. Tropical rainforest can be a reference base as a counterpoint, however, when speaking about deserts and semi-deserts in the broader sense, tundra and artificial deserts (human-transformed areas) must be considered as well besides tropical and temperate deserts and semi-deserts in the narrower sense. Land takes up approximately 150 million km2 on Earth from which approximately 15 million km2 are covered with ice, mainly in Antarctica and Greenland. **Table 2** shows potential and current values of tropical rainforests as well as areas considered as desert and semi-desert in the broader sense, excluding the before mentioned ice fields. **Table 3** shows the sources of data. Comparison of habitat types can be based on carbon stock in the biomass (t/ha), yearly carbon sequestration by primary production (t/ha/year), and biodiversity of the habitat type (species number per 10,000 km2 ). These data can be found in **Table 4** and their sources in **Table 5**.

These habitats offer a wide range of ecosystem services, among others due to the climate regulation role of the assimilated and retained carbon stock. Monetary value of these is shown in **Table 6**, based on a price of \$11 per ton (Interagency Working Group, 2013).

**Africa km2**

Lowland

4.0177 × 106

–

7.0721 × 106

4.5400 × 106

–

0

3.4907 ×

106–1.7700 × 106 0

rainforest

Deserts

1.7022 × 106 1.0932 × 106

> Tundra

Human

1.4140 × 103

–

7.0490 × 103 1.4854 × 105

–

2.5700 × 102 1.8185 × 105

–

4.3900 × 102 − 3.8400 × 104

4.4390 × 103 − 1.1406 × 105 In the case of natural ecosystems, the first number shows the area before human interference, whereas the second one shows the remnant at the turn of the millennium. In

the case of human areas, the first value refers to the 1700s, whereas the second one refers to the turn of the millennium.

4.9000 × 101 − 1.3871 × 104

1.3647 × 104 − 5.3840 × 105

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areas

**Table 2.**

Potential and current areas.

4.1679 × 104

0

0

1.8922 × 106

1.8922 × 106

–

1.8922 ×

106–1.8922 × 106

2.6542 ×

105–2.6542 × 105 0

–

2.7405 × 106 8.7276 × 105

–

2.2211 × 106 5.8855 × 105

–

1.3390 ×

107–6.7763 × 106 0

8.7000 × 105

**South** 

**North** 

**Asia km2**

**Europe km2**

**Pacific km2**

0 3.9828 ×

106–3.6949 × 106

3.9357 ×

4.0497 ×

106–4.0497 × 106

107–2.2865 × 107

1.4581 ×

107–7.8000 × 106

**Total km2**

**America km2**

**America km2**


Vegetation types have reached various levels regarding adaptation to the abiotic conditions of the given habitat, which is also shown by the distribution of plant life-forms. Long-living K-strategists and phanerophyte life-form are dominating where vegetation has been able to adapt efficiently to existing conditions. However, where the habitat is rather a "struggle zone", shorter-living r-strategists, herbaceous annual, or rosette plants are dominant (see **Table 1**).

**cryptophytes**

— — — 10–20% 60–80% 10–20%

40–50% 5–10% 10–20% 10–20% 5–10% —

1–5% 1–5% 60–70% 20–30% — —

Thus, deserts and semi-deserts are "front lines" of the expansion of biosphere, and therefore, their research (similarly to tropical rainforests) is highly important regarding life and future

Global ecological importance of deserts and semi-deserts in the broader sense can be estimated according to their area and indicators of their vegetation. Tropical rainforest can be a reference base as a counterpoint, however, when speaking about deserts and semi-deserts in the broader sense, tundra and artificial deserts (human-transformed areas) must be considered as well besides tropical and temperate deserts and semi-deserts in the narrower sense.

 are covered with ice, mainly in Antarctica and Greenland. **Table 2** shows potential and current values of tropical rainforests as well as areas considered as desert and semi-desert in the broader sense, excluding the before mentioned ice fields. **Table 3** shows the sources of data. Comparison of habitat types can be based on carbon stock in the biomass (t/ha), yearly carbon sequestration by primary production (t/ha/year), and biodiversity of the habitat type

These habitats offer a wide range of ecosystem services, among others due to the climate regulation role of the assimilated and retained carbon stock. Monetary value of these is shown

in **Table 6**, based on a price of \$11 per ton (Interagency Working Group, 2013).

on Earth from which approximately 15 million

**Chamaephytes Phanerophytes Epiphytes**

). These data can be found in **Table 4** and their sources in

**5. Importance of deserts and semi-deserts regarding the whole** 

of mankind.

Tropical rainforests

Ice and tundra

Tropical and temperate desert and semi-desert

4 Community and Global Ecology of Deserts

km2

**Table 5**.

**biosphere and human society**

**Therophytes Cryptophytes Hemi-**

**Table 1.** Comparison of frequency distribution of plant life-forms (based on [11]).

Land takes up approximately 150 million km2

(species number per 10,000 km2

**Table 2.** Potential and current areas.

the case of human areas, the first value refers to the 1700s, whereas the second one refers to the turn of the millennium.


**6. Main future tasks and problems of desert research in solving the** 

Global problems of our time are basically human ecological ones with the interplay of environmental and social factors. The most important global crisis phenomena are closely connected with each other, form a coherent system, and are associated with the anthropogenic

Introductory Chapter: Global Aspects and Scientific Importance of Desert Ecological Research

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**3.** Global biodiversity crisis (mass extinction of species, habitat loss, the collapse of

**5.** Global information crisis (insufficiency of scientific synthesis, overspecialization, publica-

**6.** Lack of global coordination (independent influence of 195 nation states without substan-

Several of these problems are linked to the ecological research of deserts. Among the anthropogenic causes of desertification, overpopulation plays an important role; however, this

**Figure 1.** Number of articles with keywords desert + ecology in their abstracts in the Scopus database (downloaded on

**global problems of our time**

Main crisis phenomena are:

**2.** Global climate change,

ecosystems),

tion flood), and

April 18, 2018).

disorders of the healthy functioning of the biosphere.

**1.** Global overpopulation crisis (population explosion),

**4.** Global social crisis (income scissors opening wider),

tive common planning and regulation).

**Table 3.** Sources of data shown in **Table 2**


**Table 4.** Carbon stock, carbon sequestration and species number per unit area.


**Table 5.** Sources of carbon stock, carbon sequestration and species number per unit area values.


**Table 6.** Monetary value of carbon dioxide in \$
