黄河首曲湿地退化过程中植物群落组分及物种多样性的变化

黄河首曲湿地是黄河下游生态安全的重要屏障.通过实地调查,采用空间序列代替时间序列的方法,研究了黄河首曲湿地自然退化过程中植物多样性的变化,并用对比分析的方法研究了人工排水对植物多样性的影响.结果表明:在黄河首曲湿地自然退化过程中,经沼泽、沼泽化草甸、高寒草甸到草原化草甸,优势种向中生和旱生种演替,丰富度指数和多样性指数逐渐增大,即草原化草甸>高寒草甸>沼泽化草甸>沼泽,而优势度指数却逐渐减小,均匀度指数先降低后增加,植物物种多样性总体上表现为增加的态势.人为排水后,毒杂草在群落中的比例增加,导致丰富度指数和多样性指数增加,均匀度指数和优势度指数略有降低,群落相似性系数逐渐降低,主要是由于人工排水后,生境相对中生化,部分植物在群落内的零星分布导致多样性指数和丰富度指数增加,而均匀度指数下降.人工排水虽然增加了群落内的植物多样性,但增加的植物多为毒杂草,从而使湿地向杂草型退化方向演替.

Simulation of Beta vulgaris climatic productivity and its planting climatic zoning in Hei-longjiang Province

Shouqu wetland of Yellow River plays important roles in the ecological security of the lower reaches of Yellow River. By the method of replacing time series with spatial sequence, an investigation was made on the changes of plant species diversity in the process of the natural degradation of the wetland. A co mparison was also made to study the effects of artificial drainage on the plant species diversity. The results indicated that in the degradation process of Shou qu wetland, i.e., from swamp to swamp meadow, to alpine meadow, and to steppe me adow, the dominant plants followed the pattern of hygrophytes being gradually re placed by mesophytes and xerophytes, richness index and diversity index were inc reasing while dominance index was decreasing, and evenness index decreased first and increased then. The species diversity had an overall increasing trend. Afte r artificial drainage, the proportion of poisonous weeds in the plant community increased, resulting in the increase of richness index and diversity index, slig ht decrease of evenness index and dominance index, and gradual decrease of Soren sen index. Artificial drainage made the habitat drying, which provided a chance for some mesophytes to invade, resulting in the increase of diversity index and richness index and the decrease of evenness index. On the whole, artificial drai nage increased the plant diversity in the community, but the increase accompanie d with increasing poisonous weeds, and thus, led the Shouqu wetland degraded int o weed type wetland.