陕北黄土高原灌木林的类型及其动态特性

本区在森林恢复演替中起主要作用的灌丛是狼牙刺群落、沙棘群落、黄蔷薇群落、虎榛子群。它们起源于多年生蒿类群落(茭蒿群落和铁杆蒿群落)和多年生禾草群落(黄背草群落、大油芒群落和白羊草群落)。被侧柏林、山杨林、白桦林、辽东栎林、油松林演替,大多被山杨林演替,并作为乔木林先锋类型灌木层优势种。杭子梢、二色胡枝子、胡颓子、柔毛绣线菊、水栒子、连翘等仅形成小的群落片段,可大面积作为乔木林演替顶极或中后期群落灌木层优势种出现。

THE TYPES AND DYNAMIC CHARACTERISTICS OF SHRUBS ON LOESS PLATEAU IN NORTH SHAANXI

The main bushes are Sophora viciifolia community,Hipp- ophae rhamnoides community,Rosa hugonis community,Ostryopsis dav- idiana community on recover succession of forest in this region.They or- igiante from perennial Artemisia community(Artemisia giraidii commu- nity,A.gmelinii)and perennial poion(Spodiopogon sibiricus communi- ty,Themeda triandar community and Bothriochloa ischaemum community). They are succeeded by the Quercus liaotungensis forests,Pinus tabulaef- ormis forests,Populus davidiana forest,Betula platyphylla forests;The majority are succeeded by Populus davidiana forest,and they are domina- nt species of shrub layer in initial types of arborous forests.Some shrub can form only community part,these shrub are campylotropis macrocar- pa,Lespedeza bicolor,Elaeagnus umbellata;Spiraea pubescens;Cotoneast- er multiflorus,Forsythia suspensa,etc.they also can form dominant sp- ecies of shrub layer in climax or later period types of arborous forests.