Annals of Arid Zone 43(2): 129-138, 2004

Human Influence on Desertification of Northeast Khorasan Province, Iran

C.M. Carivanil, E.N. Molchanovl and H. Shahandeh2

I Natural Resources Research Center of Khorasan, Mashhad, Iran2 v. v. Dokuchaev Soil Science Institute of Moscow, Russia, and Texas A&M University, CollegeStation, TX, USA

Abstract: Map of desertification process in the northern Khorasan region was compiledadopting methodology of FAO-UNEP and criteria devised by the Desert Instituteof Turkmenistan for arid, and semi-arid regions. Based on Landsat-TM data, adesertification map of the region in 1972 was prepared and compared with human-induceddesertification map compiled for northern Khorasan in 1999. -SoiL geologicaLtopographic, climatic, agricultural, and sociological information were incorporatedin compiling these maps. Data collected show that about 87% of the northernKhorasan region is affected by desertification, of which 55% is severely and veryseverely desertified. Around 6% of the area is not affected by desertification and8% is a natural desert. The degradation of vegetation cover caused by human activitiesis the most extensive form of desertification, followed by water erosion, secondarysalinization, and wind erosion. These cover 47%, 34%, 6%, and <1% of the area,respectively. Reversal of desertification in the early stages is essential in part ofnorth-east Khorasan province before the region becomes severely desertified.

Key words: Soil degradation, vegetation degradation, overgrazing, desertificationin Iran.

Classification of desertification in termsof severity of the problem was fi'rst reportedin the map of desertification of world aridland by Dregne et al. in 1977. In the sameyear Kovda (1977) reported that in WestAsia 8 to 16.8% of land was very severely,7.3 to 16.5% severely, and 5.6 to 12.8%moderately affected by the process of

- desertification. Kharin (1986) showed thatin West Asia almost all arid lands wereaffected by desertification. In a deserti-fication map developed for continent ofAsia using the FAO-UNEP model in scaleof 1: 10,000,000, Kharin et al. (2000)concluded that about 20% ofland had slight,41 % moderate, 21 % severe, and 18% verysevere form of desertification. Of this, about59% of desertification was related to

degradation of vegetation cover, 8% to watererosion, 2% to wind erosion and about7% to soil and water salinization.

In Iran there were no periodic droughts,in recent years and precipitation receivedwas normal (Garivani, 2001). Human-induced action, rather than climatic factors,is proposed to be at the core of desertificationprocesses in Iran. Babaev et al. (1997)reported that about 80% of the land in Iranwas in danger of desertification and majormanifestations were overgrazing, winderosion and destruction of rangelands. AnESCAP (1988) report concluded that themain reasons for land degradation in Iranare human pressure on natural resources likeovergrazing, expansion of dry farm ing,immigration, cultivation of marginal lands,

130 GARlV ANI et at.

and inefficient use of water resources. Nemati(1986) stated that Iran's native forageproducing lands had been grazed by domesticlivestock since the dawn of history.Livestocks now exceed the forage producingcapacity at least five-fold. Destructivepractices include: (1) grazing by excessivenumber of livestock, (2) grazing too earlyin the spring or grazing year-long or toolong, (3) increased fuel- gathering of rangeplants needed for forage and ground coverand, most significantly, (4) the widespreadplowing and cultivation of land unsuitedfor dry farming.

The objectives of this study are todetermine and evaluate the desertificationprocesses and to compile maps of areaswhich are subject to anthropogenicdesertification in the northern Khorasanprovince in Iran.

Materials and Methods

The studied area is part of Khorasanprovince in north-east Iran which includesnine administrative regions with a total landarea of 61,439 km2

. The area lies betweenlatitudes 35° 30' Nand 38° 15' N bylongitudes 55° 55'E and 60° 10'E. Humanactivities in this region go back to thousandsof years. The area is part of a mountainousregion confined to the Kopedag and Aladag-Binalud mountain' ranges stretching intoTurkman and Khorasan province (Fig. 1).The climate is arid to semi-arid with amaximum rainfall of 350 to 400 mm athigh elevations.

To assess the processes of desertificationand to produce relevant maps the methodsof FAO-UNEP (1984) and Institute ofDeserts in Turkmenistan (Kharin, 1986)were employed. Desertification .processes

were studied in 98 transects from 1996to 1999. Transects were 50 to 100 m longand 2 to 4 m wide. In each transect theyield of natural vegetation and status ofdesertification and a number of landcharacteristics were measured. The latterincluded relief forms, roughness of groundsurface, abundance of hummocks, rockdebris, stoniness, factors affecting wind andwater erosion, and extent and characteristicsof salinized land. Water erosion was studiedusing aerial photographs and topographicmaps as well as field survey and analysis.The number of water galls, rills and gullieswere determined within a one hectare samplein every land formation.

From the above information, a map ofarid areas affected by desertification in thenorthern part of Khorasan province wascompiled at a scale of 1:2,500,000 in 1999.This information was also used at a largerscale (1 :250,000) for two regions ofBojnurdand Esfarayen in northern Khorasanprovince to evaluate the advancement ofdesertification from data obtained fromLandsat-MSS in 1972 and Landsat- TM in1988-89. Preparation of data layers formapping purposes was accomplished byusing ARC/INFO, GIS software package(Needham and Viuex, 1989) and creationof area polygons in the ARCVIEW module.In this study attempts have been made todevelop the computer methodology forpreparation of desertification maps.

Results and Discussion

A map of human-induced desertificationcompiled for northeast Khorasan region anddata collected for types and classes ofdesertification processes are shown in Fig.1 and Table I, respectively. More than 86%

HUMAN INFLUENCE ON DESERTIFICATION

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Tah/e I. Tvpe (~nd class of human-induced desertification in northern Khorasan province in /999 (areain km-)

Desertification classSlight Moderate SevereI087( 1.8t) 2786( 4.5) 18437(30.0)

8094(13.2) 9915(16.1 ) 2834(4.6)0 302(0.5) 0606( 1.0) 1634(2.7) \278(2.\ )9787( 16.0) 14637(23.8) 22549(36.7)

Degradation ofvegetation coverWater erosionWind erosionSalinizationTotal

Badlands

Areas not affected by desertificationPopulation centersTotal

t Percentage of total area affected by desertification.

282(0.5)

oo6161(10.0)

28\89(45.9)

2\125(34.4 )302(0.5)\278(2.1 )

54\34(86.5)475\(7.7)3359(5.5)197(0.3)61440( 100)

of the total land area in northem Khorasanarea is under different degrees ofdesertification processes. The most damagingtype of desertification was the degradationof vegetation cover, which accounted for45.9% area, followed by water erosion,secondary salinization, and wind erosion thataffected 34.5, 5.8, and 0.5% of the area,respectively. The degree of water and winderosion was mostly slight to moderate.However, the salinization was mostlymoderate to severe. Areas not influencedby desertification consisted only of 5.5%

2or 3,359 km of total land area (Table I).These areas are mainly located in valleysbetween mountain ranges that have roughterrain which make it difficult for animalsand human access to destroy vegetation.

Water erosion (34.4%), whichaccompanied degraded land cover and winderosion, was more than 4 times higher thanthat observed for some Asian minorcountries (Kharin et al., 2000) likeTurkmenistan that neighbor Khorasan

province. The reasons are thought to belack of water conservation practices inrangelands and farmlands. Plowing in thedirection of slope in hilly and mountainregions and use of technology andmachinery that is not for fragile dry goodecosystems are among the majorcontributors to desertification by watererosion.

Secondary salinization of irrigated soilsis the main reason for desertification insome areas (Table I, Fig. I). Salinizationwas widespread in the south-east ofintermountain valley of Keshef-rud. Tedgenand Kalshur River and in the transitionalareas near the border of Iran withTurkmenistan (Fig. I). The reasons couldbe poor quality of irrigation water andincreased pumping of water from deep wells.During 1986 to 1996 the number of wellsincreased from 4.268 to 6,676 and electricalconductivity of some wells has increasedfrom 500 ~mohs to more 3,000 ~mohs(Garivani, 200]). Most irrigation water

HUMAN INFLUENCE ON DESERTIFICATION 133

comes from springs, water conduits andrivers that are slightly to moderately salineand are applied to soils without properdrainage.

Historically, wind erosion was not aprevai Iing factor of desertification in theareas where these occurred. Deflation orwind erosion was entirely absent in theseareas during 1960-1970'5, apparentlybecause of better plant cover on the landat that time (Garivani, 2001). In recentyears wind erosion has been recognizedas contributing to desertification of north-eastern Khorasan province, especially inthe border area close to Turkeminestan.This may be due to climate change inAsia Minor, especially in the KarakomDesert. For example, in north-east Khorasanin recent years the number of events havingwinds with a speed of 4,m s-I have increasedto 736 per year.

In general, desertification in northernKhorasan province is in agreement withresults of study by Babeav et at. (1990)that about 80% of land in Iran is threatenedby desertification. Arid lands are subjectedto frequent environmental stresses,including poor soil conditions. The soiland plant cover in northern Khorasan arevery vulnerable to external forces. Soilslocated in the mountainous and higheraltitude zones are shallow Aridisols(Sierozems) with dry steppe vegetation,whereas in semi-savanna low altitude areassoils are deep, more developed, and moreresistant to desertification (Nechaeva, 1978).

Growth of desertification

To elaborate on the extent and progressof human-induced desertification processestwo regions of Bojnurd and Esfrayen in

north-east Khorasan province were selectedfor further studies. A desertification mapof this region was prepared in 1972 fromLandsat data (Fig. 2). The results werecompared with those observed in the year1999. Data are shown in Tables 2 and3, respectively. Similar to results of wholeregion, the degradation of vegetation coveris the main process of desertification forboth areas. Similarly in Esfarayen regionalmost the entire land area was affectedby desertification regardless of the yearmonitored (98.5% in 1972 and 95.0% in1999). However, during the past 27 years,from 1972 to ]999, the area influencedby a slight degree of desertificationdecreased by 18.2% (from 39.2 to 21.0%),the area with a moderate degree ofdesertification increased by 8.6% (from 17.1to 8.5%), and new areas with a severeor very severe degree of degradationemerged (Table 3). In 1999 from about6.2% of total land area vegetation coverwas very severely degraded, while 7.6%of the total land area was moderately orseverely affected by secondary salinization.Secondary salinization or very severedegradation of vegetation cover was notaffecting the land area of Esfarayen in 1972(Fig. 2).

In the Bojnurd region (Table 2) thetotal area affected by desertification changedonly marginally. It increased from 73.7%in 1972 to 75.2% in 1999, but the rateof desertification class changed dramaticallyfrom slight and moderate to severely andvery severely. For example, the degradationof vegetation covers of severe and verysevere forms increased by 36.] %, and watererosion by 3.8% in the last 27 years. In1999 mapping of the region, it was observed

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HUMAN INFLUENCE ON DESERTlFICA TlON 135

Table 2. Extent of human-induced desertification in model polygon Bojnurd in northern Khorasan provinceover the past 27 years (1972-1999) by type and class (area expressed in km

2).

Desertification type Year Desertification class Total landtSlight Moderate Severe Very severe

393 (7.5) 387 (7.4) 2605 (49.7) a

1999

Water erosion 19721999

Wind erosion 19721999

Salinization 19721999

Total landt 19721999

Badlands 19721999

Areas not affected by 1972desertification 1999

Population centers 19721999

Total 19721999

120(2.3) 5(0.1)

1214 (23.2) 56 (1.1)712 (13.6) 658 (12.6)

Degradation ofvegetative cover·

1972

449 (8.6)

263 (5.1)2056 (39.2)1095 (21.0)

231 (4.4)443 (8.5)894 (17.1)

2341 (44.7) 327 (6.2)

59 (1.1)149 (2.8)

165 (3.2)2664 (50.8)2655 (50.7) 327 (6.2)

3385 (64.6)

2793 (53.3)

1328 (25.3)

1519T (29.0)·

449 (8.6)

659 (12.7)5163 (98.5)

4971 (95.0)50 (1.0)38(0.7)

23 (0.4)226(4.3)

6 (0.1)

7 (0.1)

5242 (100)5242 (100)

t Total land area affected by desertification within each type and class; t Percentage of the total areathat affected by desertification.

for the first time that an estimated 10%of total land area was desertified with verysevere degradation of vegetation cover andvery severe degree of water erosion.

In general, the results from maps anddata collected for the Bojnurd and Esfarayenregions revealed that processes ofdesertification caused by human activitieshad been going on in this region evenbefore 1972. The area has been exploitedbeyond its carrying capacity for a longperiod of time (Hassan and Dregne, 1997).A survey of the area shows that large areasofforest and bush-lands ha~e been destroyedfor fuel, and lands with very steep slopes

have been plowed extensively. Human andanimal populations have increasedsignificantly. Population density in citiesand villages increased from 26.9 personkm-2 in 1975 to 57.4 person km-2 in 1996,and the number of sheep and goats increasedfrom 7 million in 1964 to 14 miIIion in1994 (Garivani, 2001).

There is also direct effect of migrationon desertification in this region. Data revealthat between 1976 and 1996 more than.1512 villages in this region had beenabandoned and the population migrated tocities. For example, the population ofBojnurd and Esfarayen cities increased by

136 GARrV ANI el al.

Table 3. Extent of human-induced desertification in model polygon Bojnurd in northern Khorasan provinceduring past 27 years (/972-1999) by type and class (area expressed in km2).

Desertification type Year Desertification class Total land:r.Slight Moderate Severe Very severe

Degradation of 1972 347 (2.0) 6445 (36.6) 1086 (6.2) 0 7878 (44.7)vegetative cover

1999 42 (0.2) 786 (4.5) 5911 (33.6) 1530 (8.7) 8269 (47.0)Water erosion 1972 2016(11.5) 1122 (6.4) 210 (1.2) 0 3384 (19.0)

1999 669 (3.8) 1856 (10.5) 663 (3.8) 208 (1.2) 3396 (19.3)Wind erosion 1972

1999Salinization 1972 378 (2.2) 1375 (7.8) 1753 (10.0)

1999 64 (0.4) 399 (2.2) I I 13 (6.3) 1576(8.9)Total land-r 1972 274 I (15.6) 8942 (50.9) 1296 (7.4) 12979 (73.7)

1999 775 (4.4) 3041 (17.2) 7687 (43.7) 1738(9.9) 13241 (75.2)Badlands 1972 2719 (15.4)

1999 2622(14.9)Areas not affected 1972 1901 (10.8)by desertification 1999 1731 (9.8)Population centers 1972 8 (0.05)

1999 13 (0.08)Total 1972 17607 ( 100)

1999 17607(100)

t Total land area affected by desertification within each type and class: + Percentage of the total area+that affected by desertification.

3 and 4-fold in the last twenty years(Garivani, 200 I).

One of the main causes for desertificationin this region, as witnessed in many partsof world, is overgrazing, especially inmarginal lands. It is documented that themost serious desertification occurs alongthe marginal zones of the deserts (Dregneand Chou, 1992; EI- Baz, 1991). In northernKhorasan, especially around the Bojnurdarea, desertification expanded in alldirections of badlands or natural deserts(Fig. 2). For example, forest areas adjacentto natural deselis that were highlighted bythicker border lines, diminished by more

than 50% from ]972 (Fig. 2) to 1999 (Fig.I). In fact in some regions forest areasare totally destroyed (Figs. I and 2). Theprocess of desertification due toovergrazing, as stated by Milton e/ 01. (1994)is initiated by domestic. livestock thatcauses a change in the age structure ofplant populations, leading to a decreasein rangeland biodiversity and productivity,and resulting in a reduction of perennialplant cover, accelerated erosion andincreasingly extreme temperaturefluctuations on the soil surface. Besides.overgrazing is accompanied in these areasby continued plowing and tillage that cause

HUMAN INFLUENCE ON DESERTIFICATION 137

soils to lose what little organic matter theycontain, resulting in poor soil physicalconditions and low soil fertility (Garivani,2001).

Conclusions

The causes of desertification in thenorthern part of Khorasan province in Iranare natural and anthropogenic. Naturaldeficiencies include extreme temperature,uneven scattered rainfall, strong winds,dissected relief that aids water erosion, poorsoil structure, sparse plant coverage,flooding, and a fluctuating water table withhigh salt content. The anthropogenic factorsinclude overgrazing, increasing populationdensity, uncontrolled grazing, destructionof wood and shrub vegetation, lack ofefficient control on water and wind erosion,mismanagement of irrigated lands anduncontrolled and irrational expansion ofurban and industrial activities.

In the Khorasan provll1ce humanactIVities involved in processes ofdesertification are complex and one processcannot be totally responsible fordesertification. During the last 27 years,from 1972 to 1999, human activitiesconsiderably accelerated the rate ofdesertification. Cooling of Central Asia anda sharp increase in glacialation andconsequent drought in the first decade of20th century might also have contributedto desertification of this area. Le Houerou(1996) states that in developing countriesdesertification can be prevented and curedif the demographic growth is lowered andif the other sectors of the economy canabsorb the surplus population of thedrylands. In the case of Iran, demographic

growth is probably not the problem as thishad been drastically dropped to around 2%.

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