|其他摘要||The relationship between vegetation distribution and environmental factors is a central issue in ecological research. However, our understanding on their relationship at present is limited to qualitative, local, certain species, and is still not enough to reveal their complex relationship. Additionally, biomass allocation is an important theme in plant life history, and provides the basis for understanding the response or adaptive strategies of plants. Consequently, to further understand the relationship between herbaceous plants and desert environment, this research was carried out based on the following two aspects. Firstly, the distribution characteristics of herbaceous plants on sand dune and its relationship with soil physical-chemical properties were investigated. Secondly, the biomass allocation patterns were examined among three life-form herbaceous plants (i.e., ephemerals, ephemeroids and annuals).
Major findings: (1) Distribution of herbaceous plant in different parts of sand dune exhibited a clear selectivity. The species of herbaceous plants on the bottom, middle and top of sand dune were 22, 17 and 19, respectively. (2) As soil in the middle and lower part of sand dune had higher contents of water, salinity, organic carbon, total nitrogen and total phosphorus, which resulted in higher density, coverage and aboveground biomass of herbaceous plants. While, at the top of the sand dune where the soil water and nutrient content were poor, the corresponding herbaceous plants was of higher species diversity but lower coverage and aboveground biomass. (3) Total nitrogen and total phosphorus of the soil, acted as critical factors, imposed significant influences on the distribution characteristics of herbaceous plants (p < 0.01), especially the coverage, species diversity and aboveground biomass of herbaceous layer. (4) Ephemerals, ephemeroids and annuals had difference in the biomass allocation ratios, among which R/S of the three life-form plants showed that: ephemeroids > ephemerals = annuals, and the value of R/S were 1.676, 0.157 and 0.148, respectively. (5) For the six dominant species (ephemeral plants: Nepeta micrantha, Hyalea pulchella, ephemeroids: Eremurus inderiensis, Scorzonera pusilla, annuals: Bassia dasyphylla, Ceratocarpus arenarius), the relationship between R/S and plant size was remarkable power function, and R/S declined significantly with increasing plant size. Additionally, apart from Eremurus inderiensis, the leaf biomass ratio of the rest five dominant species declined significantly with increasing plant size. (6) Ephemerals (Nepeta micrantha, Hyalea pulchella), ephemeroids (Eremurus inderiensis, Scorzonera pusilla) and annuals (Bassia dasyphylla, Ceratocarpus arenarius) had difference in allometric relationship between root and shoot. While leaf and root of above three life-form herbaceous plants all showed an isometric relationship, which indicated they had strong functional convergence to arid desert environment.|