在各树种不同配置方式试验研究的基础上,提出了大面积农田林网杨树与其它树种的多样性与稳定性混交型构架,建立了各种混交林带.试验得出杨榆、杨柳混交的"对称式行混"(U P P U和S P P S)形式较佳,结构较合理;运用"边行效应原理"营造的林带,通过不同株行距试验对比,内行距为3m的林带树木胸径生长分化程度弱于内行距为2 4m的林带,而内行距为2m的林带树木胸径生长分化较为严重.
A thorough analysis on its natural environment as well as social economic status of the hilly-gullied loess region is presented. A small watershed, the dominant landscape unit of the region, has been singled out for further and specific study on landscape pattern and function, its social and economic distinctions. The authors proposed several principles based on its eco-economic background study, which includes water balance and efficient use principle, co-development of grass and agro-forestry principle, location optimization principle. Integrated with detailed analysis of a small watershed, an eco-productive paradigm for the loess land's development based on a small watershed scale was worked out. It consists of circle pattern with villages at core for high efficient agriculture production, hierarchical pattern along the slope for eco-economic development, point-axis pattern for commodity production and circulation in small watersheds and core-margin pattern for exchanges among watersheds.
