Climate is the most important factor that determines vegetation types and the distribution of species,and, accordingly,these features are two of the most prominent indicators of climate change. Currently,scientists generally agree that climate change will inevitably lead to changes in plant community structure and function,and if this change continues, the effects will be profound and enduring. Existing research shows that simulated warming causes an increase in biomass in Deschampsia caespitosa,Carex alrofusca,and Leymus chinensis; as climates change,these constructive species and their main companion species within a Kobresia humilis meadow have experienced an advancement in their spring phenology and a delay in their autumn phenophase. In addition,the photosynthetic rate of Deschampsia caespitosa in a Northwest Sichuan alpine meadow has increased. Although the change in stomatal conductance was irregular,a significant decrease has also been observed in the sodium,potassium,and phosphorus content of leaves. However,relatively little research has been conducted on the effects of simulated warming on the genetic structure and diversity of plant populations. Against the background of global climate change,the temperatures of the Inner Mongolian desert steppe have become unevenly elevated,with average annual temperatures increasing from 8.1℃ in the 1950s to 9.0℃ in the 1990s. The present study explores the effects of global warming on the genetics of wild forage plant populations with different life forms in desert steppe habitat,in an effort to elucidate their potential to adapt to environmental change. The study site was located in the desert steppe in Siziwangqi territory of Inner Mongolia. Suspension infrared radiators were used to create a controlled warming experiment under otherwise natural field conditions. Warming began on May 3,2006. The average soil temperature at depths of 0,7.5,15,30,and 50 cm increased by 1.32,0.92,0.88,0.80,and 0.74℃,respectively,after warming for 1 year compared with the average in plots not exposed to warming. For this study,changes in genetic diversity and structure were analyzed in four plant populations: (1) small half shrubs,represented by Kochia prostrata; (2) perennial grasses, represented by Stipa breviflora; (3) perennial forbs,represented by Allium tenuissimum; and (4) annuals and biennials, represented by Salsola collina). The study was conducted under simulated warming pressure and genetic analysis was performed using amplified fragment length polymorphism. The percentages of polymorphic loci in K. prostrata,S. breviflora, A. tenuissimum,and S. collina under non-warming were 11.32%,40.83%,14.29%,and 19.85%,whereas those under simulated warming were 11.32%,39.91%,13.10%,and 19.12%,respectively. The genetic diversity of the four populations measured under control and simulated warming,measured by the Shannon's information index,were as follows: K. prostrata (0.0274,0.0259), S. breviflora (0.0812,0.0899), Allium tenuissimum (0.0131,0.0084), and S. collina(0.0506,0.0456). These findings exhibited the same distributional pattern as that of Nei' s genetic diversity index for K. prostrata (0.0447,0.0430), S. breviflora (0.1354,0.1466), Allium tenuissimum (0.0267,0.0182), and S. collina(0.0811,0.0733). Cluster analysis of these four species showed that known of the species reacted significantly to the warming process,and that inter-individual clusters were not significantly different. The results of an analysis of molecular variance (AMOVA) indicated that the main source of variation among the four life form populations was within-population variation: K. prostrata (85.03%), S. breviflora (66.35%), A. tenuissimum (70.00%), and S. collina (66.52%).