关键词: 夏玉米, 需水关键期, 降水年型, 统计模型, APSIM

Abstract: With the combination of field survey and laboratory analysis, and based on the investigation data in 1986 and 2008, this paper analyzed the changes of plant species diversity (Shannon index, richness index, and Pielou evenness index) and their relationships with soil nutrient dynamics along the chronosequence of vegetation restoration in Taihang Mountains hilly region, Hebei Province of North China. After the 22 years vegetation restoration, the plant community structure and species composition in the study area had an obvious change. The life form of the community shifted gradually from herbs to trees and shrubs, and the species number of herbaceous plants had a significant decrease. The coverage and biomass of shrubs increased significantly, which altered the understory microenvironment, making the wet herbaceous plants have a remarkable decrease and inducing the decrease of species diversity and richness index. The plant species diversity was mainly affected by the contents of soil organic matter, total N, total P, total K, total Ca, and total Mg. After 22 years natural restoration, the plant community structure became more reasonable, biomass increased greatly, and species diversity had somewhat decrease, with a remarkable feedback to the nutrient contents of soil surface layer.

Key words: summer maize, critical period of water requirement, yearly precipitation pattern, statistical model, APSIM.