The vegetation of plateaus above the timberline in the Giant Mts. is formed by a mosaic of patches of dwarf pine shrubs and mat-grassland vegetation. The dwarf pines form large polycormons by clonal growth. The dynamic of shrub growth, shrub dieback and spare generative reproduction determine a specific spatial aggregation of shrubs. In the Giant Mts. the natural spatial pattern was influenced since 14th century by gradual deforestation and extensive grazing. The human activities continued from the 18th to the 20th centuries by plantation of dwarf pine shrubs. All uppermost area of the Giant Mts. belong to the National park and new management recommendations for maintenance of the stands with dwarf pine and mat-grassland mosaic in the nature closest form was required. We focused our study to the two different approaches to detect interactions between shrub and grassland patches, studying: i) local effect of shrubs on nearby grassland vegetation; and ii) species composition and diversity in different habitat types under different management regimens in the entire area of the Giant Mts. plateaus. Dwarf pine polycormons directly affect the grassland vegetation in the close neighbourhood in the distance from 0.4 to 0.6 m. In the natural shrub stands this process form a specific edge vegetation. Outside the shrubs in dense old plantations no sharp transition between edge and open area was developed probably due to overall shading intensity of dwarf pine polycormons. The young plantations do not yet influenced surrounding vegetation at all. There are not developed types of different habitats that are found in natural stands. In any plantation stand we did not find succession plots that are established after shrub dieback and that are source of high species diversity. Also the diverse-aged structure of natural stands produce more different habitats under shrubs and support diverse bryophytes flora. Therefore the highest species diversity were found in the places where dwarf pines grew under low human impact. To avoid the loss of plant species diversity in the mosaic vegetation of the Giant Mts. plateaus is necessary to cultivate the planted stands with goal to reach non even-aged stands with natural clumped structure and presence of grassland patches.