黄土区典型人工林草本层生态恢复效应

Ecological Restoration Effect of Herbage under Five Typical Plantations in the Loess Region

选择黄土区典型人工林树种小叶杨(Populus simonii)、白榆(Ulmus pumila)、青海云杉(Picea crassifolia)、华北落叶松(Larix gmelinii var.principis-rupprechtii)和刺槐(Robinia pseudoacacia),分析林下草本层的物种组成、多样性、数量特征和稳定性,通过比较人工林林下草本与对应天然草地,综合评价不同人工林林下草本生态恢复效应。结果表明:各人工林样点与对照草地的优势种显著不同,人工林样点林下草本层以禾本科植物为优势种,而对应天然草地多以多年生菊科为优势物种。除白榆样点外,其他4个样点的林下草本各类植物组成与对照草地相近,均表现为其他科>禾本科>豆科;白榆样点林下草本数量特征与对照无显著差异,但低于其他样点。刺槐和华北落叶松林下草地的生物量显著低于对照(P<0.05);对照草地物种多样性和丰富度高于人工林,但二者均匀度差异不显著;各人工林样点的稳定性参数均与稳定值20/80相差较远,说明人工林草本层群落还未达到稳定。综合评价表明,白榆和刺槐样点的生态恢复性高于其他样点。经过近40年生态恢复,调查区人工林林下草本层仍未达到对照草地水平,有待采取相应管理措施促进人工林林分草本植物的恢复。

In order to evaluate the restoration effect of herbages in different plantations and provide theoretical refer- ence for the development of planted forest systems, five typical planted tree species of loess region （including Pop- ulus sirnonii , Ulmus purnila , Picea crassi folia , Larix grnelinii var. principis-rupprechtii and Robinia pseud- oacacia） were investigated. Species composition and diversity, quantitative characteristics （biomass, density, spe- cies number, cover and height） and stability of herbal plant in five tested plantations were analyzed. The dominant herb species was Gramineae in plantations, whereas the dominant species was Compositae in control grasslands. Except U. purnila plantation, the other four tested plantations shared similar species composition. Herbage bio- mass, density, height in U. purnila plot were lower than that in other tested plots, but there was no significant difference compared with that in control grassland. The biomass of herbal plants in L. gmelinii Var. principis- rupprechtii and R. pseudoacacla plots were significant lower than that in control plots. Control had higher species diversity and abundance, but no significantly different evenness compared to five tested plantations. Stability pa- rameters of all tested plots were far from the stable value of 20/80. To conclude, U. purnila and R. pseudoacacia plots had higher ecological restorative effects than other plots. These results suggested intermediate management protocols should be cogducted to promote the herbage ecological restoration and a healthy development of plopta- tion systems at this region.