Changes of stomatal parameters of four typical species in the Loess Plateau of China over the last century

The variation and correlations of the stomatal densities, lengths, widths, areas in four C-3 species of the Loess Plateau from 1930s to 2002 were studied. The response of stomatal density to climatic change differed among the four species. Over the years from 1930s to 2002, the stomatal density did not change in Quercus liaotungensis, rising only by 1.32%, and slightly decreased by 9.79% in Ostryopsis davidiana. However, the stomatal density decreased significantly by 27.86% and 46.85% in Zizyphus jujuba var. spinosa and Sophora viciifolia, respectively. The influences of climatic change on other stomatal parameters were also species-specific. The stomatal length, width, and area varied more significantly in Zizyphus jujuba var. spinosa than in Quercus liaotungensis and Ostryopsis davidiana over the last century. The correlation analysis among the stomatal parameters of the three species showed that there were positive correlations among the stomatal length, width and area, but there were negative correlations between the stomatal length, width, area and density.