 Excessive rangeland vegetation (especially annuals) degrades the habitat through shading and resulting litter accumulation, as well as  dense vegetation inhibiting the lizards' mobility and disrupting their camouflage. Human caused habitat loss, primarily from conversion of rangeland to agricultural use, collecting for pets, and pesticide use to control fire ants are major reasons for the disappearance of Texas horned lizards throughout the Southwest.


	Central Asia is a mix of steppe, mountains, and deserts. Once it also included tallgrass prairie but, as in the United States, it was plowed under long ago. The region contains vast expanses of shrubland and grassland. The rangelands of Central Asia include these former Soviet countries: Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. There are a number of different definitions for this region depending on who is discussing it. For this presentation Afghanistan is included although that is not always the case.

	There are many factors the five former USSR countries have in common. Agriculture was greatly increased in many places during the 1950's as Russia collectivized farms and pastures and demanded that certain crops be produced, especially cotton. This resulted in water being diverted for irrigation; heavy chemical use; and pasture degradation due to overgrazing. All of these factors have contributed to widespread desertification in the area as soil became too salty to support grazing or crops. Things have changed since the breakup of the Soviet Union but many environmental problems remain.

	The separate countries are a convenient way of dividing up the area for description purposes, but most ecosystem characteristics obviously don't follow national boundaries. They can all be thought of as different aspects of the same large region commonly called the Turanian ecoregion. Many species occur in most or all of the Central Asian countries. Artemisia species are particularly ubiquitous. 

	There is a wide variety of soil type and parent matter in Central Asia. However, soils occur in patterns that are common across national boundaries. Gypsisols, light-colored soils with high gypsum content are common. The most widely distributed soil type in the Turanian bioregion is sierozem, a grayish-brown sandy-loam to loam textured soil. Large parts of Central Asia are also made up of sandy desert soil. The particularly fertile areas such as the northern Kazakh plains show chernozem type soil, or black earth.

	Kazakhstan covers 2,700,000 sq km, almost four times the size of Texas. One third of the country is covered by the Kazakh Steppe, the world's largest dry steppe region. The rest of the country is largely desert and mountains. High atmospheric pressure in this area results in hot, dry summers and cold winters with little snow. Most of the 250-300 mm of precipitation each year occurs during the spring. 

	The Kazakh Steppe varies from a completely flat plain to gently rolling hills. There are many closed basins with salt accumulation from temporary lakes. Deep depressions may also contain meadows and patches of forest. The vegetation is adapted to drought, fire, and grazing. 