Abstract: By using the Landsat TM/ETM⁺ images acquired in 1987, 1993, 1999, 2005, and 2010, the spatial distribution patterns of the settlements in Suzhou, Wuxi, and Changzhou area (including 3 prefecturelevel units and 9 countylevel units) of East China were extracted, the settlement patches were classified into 8 size classes (<5, 5-20, 20-80, 80-320, 320-1280, 1280-5120, 5120-20480, and ≥20480 hm²), and the characteristics and evolution process of the settlement size structure in the prefecture and countylevel units were comparatively analyzed. In 1987-2010, the settlements in the study area expanded 5 times in size, but the settlement growth varied with administrative units, showing different growth rhythms. The settlement size class was promoted by 1-2 levels, with the proportion of the lowest size class decreased greatly while that of the highest size class increased continuously. In addition, the second-highest size class presented very small proportions (even 0) in 3 prefecture-level units and some countylevel units. The equilibrium distribution degree of the prefecture-level units decreased continuously, but that of most county-level units showed an increasing trend. The comparison of the location conditions of equilibrium and nonequilibrium distribution types administrative units and of the landscape resource patterns within the units showed that the resource distribution pattern should be the important factor affecting the settlement size structure and its evolution trend.

Key words: Ping’ou hybrid hazelnut, saltalkali stress, electrical impedance spectroscopy, ion balance.