陕北黄土区山杏林下草本层植物群落特征研究

根据陕西省吴起县不同立地类型25龄以上山杏人工纯林和山杏沙棘混交林林下草本层植被调查数据,采用时空互代的方法,探讨了在不同立地山杏林下草本层植物群落演替方向及其生态恢复效果.结果表明,阴向缓坡、阴向陡坡和阳向缓坡山杏纯林下草本层由铁杆蒿、达乌里胡枝子群落演替到大披针苔草或铁杆蒿、大披针苔草群落,群落整体由旱生型向中生型转变,盖度和生物量增大,多样性略有降低,呈正向演替；且山杏-沙棘混交林下草本层上述指标均优于纯林.而在阳向缓坡山杏林下由星毛委陵菜、铁杆蒿群落演替到甘草、大披针苔草群落,群落整体向旱生型转变,多样性、盖度、生物量均随林龄增加显著降低,呈逆行演替.建议在阴向缓坡、阴向陡坡及阳向缓坡配置山杏这类低耗水,生长慢乔木树种,其中与沙棘等乡土灌木树种混交的模式更优；在阳向陡坡以营造生长速度适中的灌木林或自然恢复草地植被为宜.

Community Characteristics of Herbaceous Layer Under Prunus Armeniaca Plantations in Northern Shaanxi Loess Area

Based on the investigated data of the herbaceous layer under Prunus armeniaca pure forests andPrunus armeniaca-Hippophae rhamnoides mixed forests on different sites in Wuqi County,Shaanxi Province,the succession direction of the herbaceous layer under Prunus armeniaca plantations on different sitesand the ecological restoration effects of these plantations were analyzed by applying the methods of spatiotemporal inter-substitution.Results show that the undergrowth of Prunus armeniaca pure forests on shadygentle,shady steep and sunny gentle slopes changed from the community of Artemisia sacrorum-Lespedezadavuricato the communities of either Carex lanceolata or Artemisia sacrorum-Carex lanceolata.Vegetation of these communities tended to change from xeromorphic to mesophytic.The coverage and biomass ofthe undergrowth in these forests increased with increasing age,while the species diversity decreased slightly.This suggests a forward succession of the undergrowth in single-species Prunus armeniaca forests at thethree site types.In comparison,the index of community characteristics of herbaceous layer under the Prunusarmeniaca-Hippophae rhamnoides mixed forests at the three site types were better than Prunus armeniacapure forests.In single-species Prunus armeniacaforests on sunny steep slope,however,the species composition of the herbaceous layer changed from Potentilla acaulis and Artemisia sacrorum to Glycyrrhiza uralensis and Carex lanceolata.Species diversity,coverage,and biomass decreased significantly over time andthe vegetation tended to change to xeromorphic,indicating? regressive succession.We suggest that treeswith the characteristics of low water consumption and low growing speed,such as Prunus armeniaca,shouldbe placed on shady gentle,shady steep and sunny gentle slopes.Furthermore,the mode of these kinds oftrees mixed with local shrubbery,such as Hippophae rhamnoides,is more positive.For sunny steep slope,however,vegetation of shrubbery with moderate growth rate or grassland that occurs naturally is more suitable.