Research on an optimal management method of emergent macrophytes by regrowth analysis after cutting aerial shoot

这项研究有两个主要目的。一种是为了阐明两种新兴的大型植物香蒲和宽叶孜然在剪断气生枝后的不同策略。二是分析芦荟和芒属植物竞争优势的变化。2003年5月、7月、8月，对狭叶芒属植物的连续嫩枝进行露水采伐，研究不同采伐时间对其生存策略的影响。2003年7月，宽叶大叶草也被砍掉。从采伐后地上、地上和地下生物量的再生长特性、芽的特性和TNC在地上和地下生物量中的分配比例等方面定量地评价了它们采伐策略的差异。在7月份的采伐中，狭叶沙枣的地下生物量下降了约30%，而宽叶沙枣的地下生物量并没有下降。与快速运输地下物质的狭叶沙枣相反，宽叶沙枣不仅通过再生枝恢复根茎，而且通过大量的次生枝恢复根茎。利用考虑断茎的更新生长动力学模型，分析了南方红豆杉和旱地植物糖花黄杨在江河湿地恢复地的竞争与洪水流量、洪涝间隔期及其断茎时刻的关系。分析了两种树种的单种林分和竞争林分的生物量随洪水流量和时间间隔的减少情况。如果它们的茎每年都会折断，这两个物种就很难生存。但如果间隔2-5年，它们仍能存活，但优势下降。分析表明，两种树种每隔2~5年发生一次洪水断茎，可延缓湿地树种向旱地树种的过渡。不应引入只折断南美白杨茎的洪水干扰。

This research has two main purposes. One is for elucidating the different strategies of two emergent macrophytes, Typha angustifolia and Zizania latifolia, after cutting aerial shoots. Second is to analyze the change of the competitive superiority between Phragmites australis and Miscanthus sacchariflorus.Aerial shoots in T.angustifolia were cut above water in May, July, August in 2003 for investigating their strategy to survive from cutting at different timing. Z.latifolia was also cut in July in 2003. The differences of their strategy for cutting were evaluated quantitatively by re-growth characteristics of aboveground leaves, above-and belowground biomasses, the characteristics of buds and percent allocation of TNC in above-and belowground biomasses just after cutting. The below ground biomass in T.angustifolia decreased about 30% in July cutting, but that in Z.latifolia didn't decrease. Contrary to T.angustifolia that transports below ground material rapidly, Z.latifolia recovered their rhizome not only by re-growth shoots but by many secondary shoots. The secondary shoot formation was assumed also their strategy to protect their habitat.Competition between P.australis, and upland species, M.sacchariflorus, in a river-wetland rehabilitation site was analyzed in relation to flood discharge, flood interval and their stem-breaking moment and by regrowth dynamic model considering their stem-breaking. The decrease in biomass by flood discharge and interval were analyzed for monospecific stands and competitive stand for the two species. If their stem breaking is occurred every year, survival of the two species is difficult. However, if the interval is 2-5 years, they can survive but superiority of M.sacchariflorus is decreased. The analysis indicates that stem-breaking of both two species by flood every 2-5 years can delay the transition from wetland to upland species. Flood disturbance that only breaks stems of P.australis should not be introduced.