Status of Dryland and Desertification in the World

Drylands are inhabited by approximately 2 billion people globally accounting for nearly 40% of the world’s population. Approximately 54 million sq.km or 40% of the land area can be classified as drylands. Regionswise, Africa is relatively driest of the continents. Even in South America, known for its rainforests, about a third of the land is in dry zones. Asia also contains substantial drylands, with 39% of its total land mass mostly of the arid, semi-arid categories found in Central Asia and Western China.

 

The largest number of population is concentrated in the drylands with Asia having the highest - 42% of its total population, i., about 1.5 billion people living in the drylands, Africa has 41%, and South America has 30%. These inhabit mainly the semi-arid and sub-humid regions. Thus, countries with high proportion of their population in the drylands should also be at risk to dryland degradation. Some of the world’s largest cities lie within the dry zones - Beijing, Cairo, Lima, Dakar. The hyper-arid region, which are excluded from the drylands, account for 9.9% of the global land area

Extent and Distribution of Susceptible Drylands, by continent. (UNEP, 1992a)

 

Region	Area (mha)	Percentage of Total
Africa	1,286	43
Asia	1,672	39
Australia	663	>75
Europe	300	31
N.America	732	33
S.America	516	29
World Total	5,169	40

 

EXTENT OF DRYLANDS IN DIFFERENT CONTINENTS OF THE WORLD (Area)

 

EXTENT OF DRYLANDS IN DIFFERENT CONTINENTS OF THE WORLD (Population)

 

Socio-economic factors and political considerations play a very significant role in land degradation occurring in the various regions of the world. However, population levels can trigger or intensify land degradation, all other factors and assumptions being equal. This assumption is based on the existence of an inherent carrying capacity for a given land type with a given land use.

 

LINKAGE BETWEEN DESERTIFICATION AND POVERTY IN DRYLANDS OF THE WORLD
According to the 1997 UNDP Human Development report, poverty is worse in drier zones than it is in wetter zones. For example, for 10 countries of the Sahel Region in Africa, the Human Poverty Index was 25% of the humid areas and 61% for arid zones. To gain a better understanding of the link between drylands and the UNDP human development index, which provides a measure of the socio-economic development, UNSO undertook an analysis of some 90 countries. On that basis, the countries were classified into three clusters:

 

Cluster 1: Low HDI, PLVD >35%.
Cluster 2: Medium HDI, PLVD>35%
Cluster 3: Others.

Where, HDI = Human Development Index, and PLVD = Productive Land Vulnerable to Desertification.

 

LAND USE IN DIFFERENT DRYLAND REGIONS OF THE WORLD

 

A comprehensive survey (UNEP, 1992a1 ) indicated that the dominant forms of land use and land cover in drylands are irrigated and rainfed agriculture and rangelands, with forest and woodland occupying upto a quarter of all drylands. The survey concluded that 73% of the rangelands, 47% of the rainfed croplands and 30% of the irrigated areas showed some degree of desertification. It may however be mentioned that global assessments of this nature can vary from survey to survey based on the criteria used.

Dominant Types of Human Land Use (in mha) in the Susceptible Drylands (UNEP, 1992a)

 

Preliminary results of UNDP/UNSO carried out with the support of the World Resources Institute (WRI), indicate that Asia has the largest area under drylands and is home to over 1.3 billion people, over three-quarters of the total population in drylands worldwide. For most of these people, the natural resource base constitutes the primary source of livelihood. Also, the density of the population in the drylands of Asia is 3.7-4.0 times higher than in Africa and Latin America and the Caribbean respectively. Asia has 1949 million hectares of drylands, which is 46% of the continent’s and 32% of the world’s total surface area. The World Atlas for Desertification, 1992 has indicated 370.4 million hectares to be degraded. About 35% of the region’s productive land are under severe threat of desertification, resulting in an enormous loss of productivity. This covers about 35% of all irrigated land, 56% of the rain-fed cropland
and 76% of the rangelands.

 

Status of Drylands in Asia: The United Nations Environment Programme (UNEP) has estimated that desertification affects more than 1,341 mha of productive land in Asia. The Global Assessment of Human Induced Soil Degradation (GLASOD) assessed that lost productivity through desertification in Asia is ranked as the worst among the regions in the world. The losses in investment and potential production per unit in Asia were the greatest compared to other regions. More than 50% of the world’s irrigated lands affected by waterlogging and salinisation are also found in Asia, touching a large population. China and India together have the largest number of population living in the drylands and affected by land problems of desertification. It is estimated that desertification affects about 400 million people directly or indirectly in China and about 300 million in India (Beijing Report, 1997). Desertification has accelerated in countries such as China, Mongolia, India, Islamic Republic of Iran, and some of the countries in Central Asia. Other countries in the region also face a range of land degradation problems such as water and wind erosion, physical and chemical deterioration of soil as result of complex interplay of socio-economic forces and human-induced factors such as deforestation, unsustainable agricultural practices and overgrazing.

 

Extent of Desertification in Some of the Countries in Asia

 

The FAO has estimated that the world food supply requires to be increased in Asia by 75% over the next 30 years to meet the needs of the growing population. This is particularly challenging because the per capita area of arable land which stood at 0.48 ha in Asia in 1950-1955 is expected to decline to 0.25 ha by 2000. In the Indian context, the per capita area of arable land has declined far more rapidly over the past 30 years and is declining further

 

Decline in Arable Land in the World, in Asia

Per capita area of arable land	1950-55	1981	1992	2000	2025
World	0.32	n.a	0.25	n.a	n.a.
Asia	0.48	n.a	n.a	0.25	n.a

 

 

Per capita of Forest Land in Asia-Pacific Region and in the World, as of 1990

 

Country/Region	Per Capita Availability of Forests (ha)	Per capita (GNP) (US$)
India	0.08	360
Sri Lanka	0.11	470
Indonesia	0.64	560
Malaysia	1.02	2330
Fiji	1.17	1780
Tropical Asia	0.21	475
Total Asia-Pacific	0.17	602
Total Developing Countries	0.50	763
World	0.67	763

 

 

Status of Forests in Asia-Pacific Region and in the World,

Details	Tropical Asia	Asia-Pacific	Developing Region	World Countries
Growing stock of wood in natural forests (cu.m /ha)	140	125	113	114.0
Biomass in natural forests (t/ha) avail. vol. of growing stock	181	171	169	131.0
Per capita (cu.m)	28.00	18.90	54.90	71.76
Avail. biomass per capita (t)	36.27	25.76	81.73	82.37