乌梁素海野生芦苇群落生物量及影响因子分析

THE BIOMASS OF PHRAGMITES AUSTRALIS AND ITS INFLUENCING FACTORS IN WULIANGSUHAI

对内蒙古乌梁素海湿地野生芦苇 (Phragmitesaustralis)生物量的调查基础上 ,探讨了富营养化湖泊湿地水体的物理化学性质对芦苇生物量的影响。结果表明 :1 )由于环境因子的影响 ,芦苇群落生物量变化较大 ,介于 1 .73～ 3.0 0kg·m-2 之间 ;地下和地上生物量之比介于 1 .1 4～ 2 .1 9之间 ;2 )芦苇群落生物量受多种因素的影响 ,其中水深是最主要的限制因子 ,水上生物量和地上生物量随着水深的增加而增加 ,而地下与地上生物量的比值则随水深的增加而减少 ,这主要是由于水深改变了芦苇群落的结构 (群落密度 )和个体形态 (株高和株茎 ) ;3)芦苇群落生物量随着水体N浓度增加而增加。芦苇各器官 (叶、茎、根状茎和根 )的N∶P为 7.5 9～ 1 2 .2 1 ,小于 1 4 ,这也说明该水体中的N负荷是影响芦苇生长的主要限制因子 ;4 )

There is an increasing need to understand the importance of ecosystem services provided by wetlands, including nutrient storage, water quality improvement, soil organic matter enhancement and biodiversity protection. Phragamites australis (common reed) is a dominant plant in many aquatic ecosystems and plays a critical ecosystem service role in wetlands. However, few studies have focused on common reed communities, especially concerning its characteristics in eutrophic wetlands in western China. To investigate the relationship between the biomass of P. australis and the physical and chemical characteristics of water and soil (water depth, N and P water and sediment concentrations, soil organic mater and N and P content of plants), a field study was conducted in September 2002 in Wuliangsuhai, Inner Mongolia where eutrophication is a very serious problem in this arid climate. We randomly selected 15 sampling sites and determined the reed biomass with harvest method in 1 m×1 m plots. To eliminate the effects of different aged stands on biomass, we chose uniform plots of two_year old reed stands. The reed height, culm diameter and the number of shoots were measured and soil, water and plant (leave, stem, rhizome, root) were sampled, and the N and P content analyzed. The results showed that the reed biomass was as high as 1.73-3.00 kg·m 2 with a below_ground to above_ground biomass ratio ranging from 1.1-2.1. Many factors influenced reed biomass, but water_depth was the most important factor. Above_ground and above_water biomass increased and the ratio of below_ to above_ ground biomass decreased with water depth. Water_depth effected reed biomass by changing the morphology and structure of the reed community, such as reed height, culm diameter, density, and biomass allocation. There was a significant correlation between reed biomass and water N concentrations. The nitrogen to phosphorus ratio ranged from 7.59-12.21 (< 14) indicating that N limited the reed growth at the community level. Reed biomass was not correlated with water P concentrations. Soil organic matter did not influence reed biomass because the soil was primarily consisted of mineral and organic sediment with little reed litter that releases phytotoxic acids. To investigate the combined effect of the physical and chemical characteristics of water and soil on reed biomass, an equation was developed which indicated that the reed biomass of Wuliangsuhai was mainly influenced by water depth and N concentrations of the water.