Allelopathic Effects Of Main Planted Forest Trees In The Loess Plateau On Forage

There are a lot of problems in the progress of the development of plantation at present,such as skimpily stand structure, lowly species diversity, poor stability of ecosystems andfertility failure and so on. While compared to the pure forest, forest-grass compoundecosystem can improve the stand ecological conditions and increase the soil fertilityeffectively; meanwhile the undergrowth and interforest pasture vegetation also play animportant role in promoting plantation nutrient cycling and maintaining soil quality.Therefore, the artificial pure forest replaced by forest-grass compound ecosystem, and thedevelopment of undergrowth and interforest pasture vegetation has become an effectivemethod to improve the condition of plantation. This study selected Pinus sylvestri, Pinustabuliformi, Larix principis-rupprechti, Platycladus orientai, Populus simonii, Quercusliaotungensis, Betula platyphylla, Ulmus pumila, Robinia pseudoacacia, Salix matsudana,Caragana intermedia, Amorpha fruticosa and other species, studied the effect of their litterextract on the germination of several common pasture(L. bicolor, M. sativa, A. adsurgens, C.varia, V. villosa and L. perenne), and measured the related indicators of germination andseedling growth. In order to provide a scientific basis and theoretical guidance for thetransformation of artificial pure plant and the construction of forest-grass compoundvegetation. The main results are as follows:1) Pinus sylvestris litter showed the allelopathy regular of “low promotehigh-suppression” on forage; Pinus tabuliformis litter showed the allelopathy law of “lowpromote high-suppression” on Lolium perenne, other forage all showed a certain degree ofinhibition；Larix principis-rupprechtii and Platycladus orientais litter showed inhibition ongrowth of Astragalus adsurgens and Vicia villosa, other forage all showed the allelopathy lawof “low promote high-suppression”.2) Populus simonii litter showed inhibition on Leapedeza bicolor, Coronilla varia andLolium perenne, showed the allelopathy regular of “low promote high-suppression” onMedicago sativa and Astragalus adsurgens, showed promotion on Vicia villosa; Quercus liaotungensis litter showed the allelopathy regular of “low promote high-suppression” onVicia villosa，other forage all showed a certain degree of inhibition; Betula platyphylla litterhas inhibition on Leapedeza bicolor and Vicia villosa, other forage are subject to theallelopathy law of “low promote high-suppression”; Ulmus pumila litter showed theallelopathy law of “low promote high-suppression”on Leapedeza bicolor, Medicago sativa,Astragalus adsurgens and Coronilla varia, Ulmus pumila litter showed a promotion on Viciavillosa, showed a inhibition on Lolium perenne. Robinia pseudoacacia litter showedinhibition on Leapedeza bicolor, Coronilla varia and Lolium perenne. showed the allelopathylaw of “low promote high-suppression”on Medicago sativa and Astragalus adsurgens,Robinia pseudoacacia litter has inhibition on Vicia villosa; Salix matsudana litter haspromotion on Vicia villosa, have inhibition on Lolium perenne, while other forage all showedthe allelopathy law of “low promote high-suppression”.3) Caragana intermedia litter has inhibition on Leapedeza bicolor, Vicia villosa andLolium perenne. Medicago sativa and Coronilla varia all showed the allelopathy law of “lowpromote high-suppression”, Caragana intermedia litter has promotion on Vicia villosa;Amorpha fruticosa litter showed the allelopathy regular of “low promote high-suppression”on Leapedeza bicolor, Astragalus adsurgens, Vicia villosa and Lolium perenne. Amorphafruticosa litter has inhibition on Coronilla varia, but has promotion on Medicago sativa.