2001 Asiatic Herpetological Research Vol.9, pp. 113-121 Lizards of the Northern Mongolian Deserts: Densities and Community Structure 1 1 2 A. V. AND GEORGY I. SHENBROT DMITRY SEMENOV , KONSTANTIN ROGOVIN , 'A.N.Severtzov Institute of Ecology and Evolution, Russian Academy of Science, Leninsky pr. 33 Moscow ~ 1 17071, Russia, Ramon Science Center, Ben-Gurion University of the Negev, P.O. Box 194, Mizpe Ramon, 80600, Israel Abstract.- Spatial organization and population densities of three-species lizard community was studied in the Gobi Desert, Mongolia. To evaluate the effect of habitat variables on the distribution and abundance of each species we used the stepwise procedure of factor selection with ANOVA on each step. To describe the distribution of species' spatial niches in the space of environmental variables, we used stepwise discriminant function analysis (DFA). The number of species in 1-ha grid areas varied from to 4. Phrynocephalus versicolor was the only species distributed over the 91% of grids occupied. There was a positive relationship between distribution and local species abundance. A set of two to three habitat variables determined the abundance of each species. The result of DFA signify to the well pronounced segregation, but not even distribution of species spatial niches in the space of resources. Key words.- Lizards, Mongolia, community, ecology, density 91* 96* 101* 106° 111* 116' Fig 1. Map of Mongolia and location of sites where data were collected. Southern Gobi, 2-Western Gobi, 3- Eastern Gobi, 4-Barun-Churay Basin. Introduction at sites, a low level of species turnover between habi- tats, low abundance of most species and high domi- The reptile communities of Mongolian deserts are nance of only one species, Phrynocephalus versicolor. characterized by several specific features discussed A few common species have rather broad spatial elsewhere (Ananjeva and Semenov, 1986; Borkin and niches, diverse behavioral and physiological charac- Semenov, 1984; Munkhbajar, 1976; Semenov and teristics (diverse range of thermobiological patterns, Borkin, 1986; Semenov and Shenbrot, 1988). There wide active search for food items, etc.). are few species in the fauna with low species richness Vol. 9, p. 114 Asiatic Herpetological Research 2001 The degree of interest in comparative studies of transitive with no specific features of vegetation. structure and function of reptile communities Thus, only the southern (extra-arid) and northern sub- increased dramatically after seminal papers written by zones are well pronounced. E. Pianka Most of the (Pianka, 1973, 1975). ensuing The southern desert occurs mostly in the Trans- studies were devoted to the rich and diverse species Altai Gobi and is characterized by a few very dry, communities of desert lizards in Australia, south- unproductive biotopes inhabited by five lizard species western North America and southern Africa (Case, (two agamids, two gekkonids, and one Eremias spe- 1983; Fuentes, 1976; Henle, 1989; Colwell, Inger, cies). Among this group only one species, Phryno- Millado et al., 1975; Pianka,1986; Scheibe, 1977; cephalus versicolor is common in the northern Shenbrot et At the 1987; al., 1992; Simbotwe, 1984). subzone (Semenov and Borkin, 1986). same time study of species poor communities in the The northern deserts, which extend to the south- Central Asian desert can provide a significant infor- west, west, and south-east of Mongolia and along mation not only in comparison with other continents, both slopes of the Mongolian Altai and Gobi-Altai but also can help us to understand better which factors mountains, are characterized by pronounced microre- rule in reality structure and dynamic of lizard commu- lief and rich vegetation, although the main landscape nities of many species. Up to now there were only two types are the same as in the southern subzone. The examples of such studies made in China (Chang et al., vegetation in rock and gravel valleys consists of 1993;Luietal.,1992). perennial grass (Stipa), forbs, onions and succulents, The main of this was to the objective paper study and a variety of annual plant species. Shrub vegetation features of and specific spatial organization popula- is often associated with foothills and sand dunes, or is tion densities of lizard in the three-species community spread along the dry river beds (Lavrenko, 1978). The dur- Gobi Desert, Mongolia. The study was conducted difference in climate between western and eastern a research on the ing long-term program biodiversity parts of the northern Mongolian desert is not pro- of the desert and was Mongolian biota, sponsored by nounced (Murzaev, 1952); some differences exists in the Permanent Soviet-Mongolian Biological Expedi- the composition of the flora (Yunatov, 1950). tion. Lizard species Material and Methods There are four lizard species inhabiting northern Mongolian deserts: Alsophylax pipiens, Phrynoceph- desert Mongolian alus versicolor, Eremias przewalskii and E. multiocel- A map (Fig. 1) illustrates the location of desert lata. Among these, only the three last mentioned regions of Mongolia. Three desert regions to the south species are abundant and relatively widespread. of the Altai Mountains are partly separated from one another by chains of low mountains and hills. These Data collection three are Trans-Altai Gobi Alashan Gobi (South), We collected data during three field trips to the Mon- and Gobi or Basin (East) Sungarian Barun-Churay golian northern deserts in June-August 1985, 1986 Besides these deserts there (West) (Yunatov, 1950). and 1988. Forty five 1-ha grids were established in the are desert areas between the Altai and moun- Hangai Northern desert subzone (see map, Fig 1 ). Grids were cold and tains, usually called Western deserts, some distributed so that they covered the whole range of arid lands in the Lakes and Ubsu-Nur Basins Great habitats from the middle slopes of the mountains to (northwest). the clay basins and sand dunes. Each habitat type was Three arid subzones of the Mongolian desert are sampled equally. Two factors determined the number defined (Sokolov and Gunin, 1986): extra—arid of grids at a desert region: diversity of habitat types and abundance of lizards. Each was divided into desert (<50 mm of rainfall per year), real desert (50— grid smaller 20 x 20 m. The centers of 100 mm per year) and steppe—like desert (100—150 25 sample plots, were marked with 50 cm aluminum mm per year). However, the climatic border that sample plots stakes. Lizards were restricts the distribution of plants (Kazantseva, 1986; sampled by repeated, regular search of established two to four consec- Volkova et al., 1986) and animals (Podtyazhkin and grids during of their diurnal Orlov, 1986; Semenov and Borkin, 1986) exists only utive days during periods maximal all encountered lizards were between the southern part of Trans-Altai Gobi (< 50 activity. Nearly captured hand. Most of the were con- mm per year) and the northern waste belt of desert by surveys accounting ducted before the of In the rest lands with more predictable precipitation (100-200 appearance hatchlings. of the cases were not counted. Each mm per year). The narrow real desert subzone appears hatchlings cap- 2001 Asiatic Herpetological Research Vol. 9, p. 115 1. of lizard Table Density (no. ha ) species. </> s. 0) O 'o w a>a c (A "(5 c 3 TON O Asiatic Research 2001 Vol. 9, p. 116 Herpetological Results cies but with the pronounced habitat preference. The second was E. multeocellata, and the third was E. Densities and distribution through habitat przewalskii. The last species had the most restricted types habitat preference, namely sandy-loess hills in saline depressions with shrub vegetation of Nitraria sp. The results of lizard density and diversity estimations of P. versicolor was cor- on the 1-ha grids indicate the low local species diver- The abundance positively of related with its broad distribution. The of this sity in Mongolian deserts (Table 1). The number density varied from 1 to 106 individuals 1-ha species in our grid areas varied from zero to three. species per The second most abundant E. Among 45 grids there were two grids with no lizards, (Table 1). przewalskii individuals lha and the third was 21 grids with only one species. 18 grids with two spe- (44 per maximum), individuals 1-ha cies and four grids with three species. Phrynoceph- E. multiocelata (11 per maximum). alus versicolor was the only species distributed over All three species coexisted at rather high densities in with hills covered with the most number of grids (91% of grids occupied). saline depressions sandy-loess There were no Eremias przewalskii was found on 33%, E. multioce- Nitraria sp. shrubs. pronounced nega- the densities of two dominant lata on 24% and A. pipiens on 4% of grids. Regarding tive correlation between situated within this habitat distribution through the main habitat types (Table 1), species on grids type (P. P. versicolor was also the most distributed widely spe- versicolor-E. przewalskii: R"=0.04, n=20, ns). Table 2. Designation and description for the 23 habitat variables included in the analysis. Mnemonic Variable Unit RCK Content of rocks in the soil %% GRW Content of gravel in the soil %% CLY Content of clay in the soil %% SCS Sand cover area %% SCH Sand cover height cm WDS Dry river bed area %% WDD Dry river bed depth cm NRB Number of rodent burrows no/sq.m. FRB Abundance of annual forbs no/sq.m. AGR Abundance of annual grasses no/sq.m. ANN Overall abundance of annual grasses and forbs no/sq.m. ALL Perennial Allium covet %% PGR Perennial grass cover %% MIC Cover of microphyllous shrubs %% HAL Cover of halophytuos shrubs %% sue Cover of small succulent shrubs %% HLX Cover of Haloxylon %% NIT Cover of Nitraria /o /o o/ o/ SHC Overall shrub cover /o /o SV1 Perennial plant crown volume at the level 0-25 cm %% SV2 Perennial plant crown volume at the level 25-50 cm %% 0/ O/ SV3 Perennial plant crown volume at the level 0.5-1 m /o /o o/o.