【作者】 郭朝晖；

【导师】 梁宗锁；

【作者基本信息】 西北农林科技大学 ， 植物学， 2007， 硕士

【摘要】 土壤养分,尤其是限制性资源的空间分布状况在一定程度上决定了群落结构与生物量,由于组成种的个体形态、生理生态和生活力等各方面的差异,对异质条件下富营养斑块的选择性利用能力不同,因而在土壤养分总量相同的情况下,异质条件下群落结构与生物量会有所差别。因而研究土壤养分分布方式对群落结构和生物量的影响,对揭示植被演替规律具有重要的意义。本试验选定8块无人为干扰或人为干扰较少的撂荒演替先锋群落样地为研究对象,进行群落调查和环境条件测定。群落调查记载样方内各种植物名称、高度、盖度、多度和地上生物量。环境条件测定包括地理位置、坡向、坡度和海拔、土壤水分与土壤养分等,采用典型相关分析方法,对这8块样地进行了群落间异质性与环境因素差异间的关系进行了分析。同时,选择位于峁顶、植被分布较均匀的猪毛蒿群落,以及土壤养分分布较均匀的苜蓿地作为样地,在其中间划分小区,将肥料按一定格局施入小区,使土壤养分在空间上呈均匀和异质两种分布形式,并采用相关分析方法,以研究土壤养分的不同分布方式对群落结构和生物量的影响,结果如下:1群落间异质性大于群落异质性,且群落间异质性与环境因素差异多数为正相关,说明环境对摞荒演替前期群落组成与结构起到了一定的塑造作用,典型相关分析进一步表明群落间异质性,主要是群落组成异质性,有49.6%是由环境差异引起的。土壤全氮、磷和钾含量与群落间组成异质性有较强的正相关关系,说明氮、磷和钾肥对摞荒演替中群落组成与结构有较大的影响,因此在草地植被恢复与重建应注意施肥料,特别是氮肥的施用。2复合肥在小尺度下,匀质施肥更能提高群落的平均高度,中尺度和大尺度下,异质施肥更能提高群落的平均高度。在同一尺度同一施肥强度下,匀质施肥降低了群落的平均密度。在小尺度和中尺度下,低肥和中肥的匀质施肥都要比异质施肥更能提高群落的生物量;而在小尺度和中尺度的高肥以及大尺度的高中低肥条件下,异质施肥更能提高群落的生物量。匀质施肥使不同尺度下的群落物种多样性和均匀度都随着施肥量的增加而下降。异质施肥在小尺度和中尺度下,群落样地中物种的多样性和均匀度随着肥量的增加而增加,优势度降低;在大尺度下,异质施肥以中肥强度下的群落物种多样性和均匀度最高。3通过不同肥料不同施肥方式对苜蓿地产量影响的实验可以看出,苜蓿地以施用复合肥效果较好,且高肥强度下的异质施肥产量最高。更多还原

【Abstract】 The space distribution status of soil nutrients, especially the restricted resources, determine the structure and biomass of community to some extent. Because of the differences in individual morphology, eco-physiology and viability between component species, the difference in selectivity and utility to richness plot under heterogeneity condition, the structure and biomass of community will different, even though the amount of nutrients is the same, when the heterogeneity of soil nutrients exists. So the study of the effects on community structure and biomass of the soil nutrients, different distribution pattern is very important to the revelation of the law of vegetation succession.In order to investigate the characteristics of the communities and the environment, eight communities were selected in this experiment, which were abandonment succession pioneer communities and had no or had a little disturbance. The community investigation included records of the species name, height, coverage, abundance and biomass. The environment determination included location, slope direction, slope degree, altitude, soil moisture, soil nutrients. Spatial heterogeneity and their standing condition differentia of the eight communities was analyzed using canonical correlation analyzing method. Meanwhile the Artemisia scoparia community in which plants dispersed homogeneously on the loess hill and the Medicago sativa plot in which soil nutrients was homogeneous were chose,then divided them into plots and applied compound fertilizer and organic fertilizer to the Artemisia scoparia community, compound fertilizer and urea to the Medicago sativa plots. The fertilizer applied into plots as two kinds of manner, one of which made the soil nutrients homogeneous, the other made soil nutrients heterogeneous. The effects of different fertilizer distribution format on the structure and biomass of community were studied. The results showed that:1 Spatial heterogeneities between communities are greater than that of within communities, and spatial heterogeneities between communities and most of standing conditions differentia are positive relationship, both of which imply environments can act on communities composition and structure of early succession stage, and further canonical correlation show that about environment differentia account for 49.6% of heterogeneities between communities. Whether in person or canonical correlation analysis, heterogeneities between communities and its nitrogen differentia show strong positive relationship, which implies that nitrogen is the main factor acting on heterogeneities between communities, besides nitrogen, soil phosphorus and potassium show significant positive relationship, thereby fertilizer, especially nitrogen should be fertilized in re-vegetation of abandoned land.2 As to compound fertilizer, the average height of the communities was higher when the fertilizer was distributed homogeneously at small scale and when the fertilizer was distributed heterogeneously at middle and big scale. At the same scale and under the same fertilization intensity, the density of the communities decreased when the nutrients was distributed homogeneously. At small and middle scale under low and middle fertilization intensity, the biomass of the communities was higher when the fertilizer was distributed homogeneously. At small and middle scale under high fertilization intensity, at big scale under all fertilization intensity, the biomass of the communities was higher when the fertilizer was distributed heterogeneously. The higher the fertilization intensity was, the lower the diversity and uniformity of the communities when the nutrients was distributed homogeneously at all scales. The higher the fertilization intensity was, the higher the diversity and uniformity of the communities when the nutrients was distributed heterogeneously at small and middle scale and was highest at big scale under middle fertilization intensity.3 According to the study of the effects of different fertilizer and different distribution patter, we can see that the compound fertilizer is better for the Medicago sativa plot, and the yield is highest at big scale under high fertilization intensity using heterogeneous fertilization.更多还原