黄淮海平原封丘试区水生植被

AQUATIC VEGETATION IN THE FENGQIU EXPERIMENTAL AREA OF THE HUANGHUAIHAI PLAIN

对封丘试区水生植被的研究表明:挺水植物的种类少,但其分布和生物量在该地区占有绝对优势。在本地区的两大代表水体中其生物量(鲜重)可达2.9×10^(?)kg和0.13×10^(?)kg。沉水植物的分布面积在其中一个主要水体(曹岗湖)分布较广,但其生物量仅为3.2×10~3kg(鲜重),其生长的制约因素是水体中过多的草食性鱼类和水体过低的透明度。对植被中的主要经济种类芦苇的生长研究得出了其生物量与时间、密度和均长之间关系的函数。

Studies on the aquatic vegetation in Fengqiu Experimental Area show that emergent plants belonged to a dominant vegetation type although the number of their speies was rather low and their total biomass was considerably high, with a maximum biomass of 2. 9×10^(8) kg (FW) and 1. 3 × 10~7kg(FW) respectivetly in two major water bodies of the area. The distribution area of emerged plants was also the largest among all vegetation types in almost all kinds of water bodies except in Caogang Lake, in which submerged plants occupied more open water area of the lake but the peak biomass of submerged plants was reaching up to mere 3. 2 ×10~3kg(FW). Major types of association are described in the paper. Growth analysis shows that emerged plants grew well in the area. Effects of water depth on their growth was considered to be unimportant. Nutrient content was also unlikely to limit the growth. Sediment organic content and redox potential were the possible limiting factors. Fishery capacity of submerged plants in Caogang Lake was calculated to be 53. 8kg grass carp per year. It is concluded that grazing pressure and low water transparency were the limiting factors to the growth of submerged plants. Growth analysis also shows that Phrag mires com munis mainly germinated from March to May and flowered from July to August. Its peak biomass was reached in August, then entered its reproduction period. Relationship between biomass and other growth indices of P. communis was analysed. The equation shows that instantaneous biomass was positively linear related to its density. The relationship between major growth indices and time indicates S-shaped curve.