松嫩平原两种碱蓬群落土壤种子库通量及幼苗死亡的分析

ANALYSIS ON THE FLUX OF SOIL SEED BANK AND THE SEEDLING MORTALITY IN THE COMMUNITIES OF TWO SPECIES OF SU AEDA IN THE SONGNEN PLAIN IN CHINA

角碱蓬和翅碱蓬都是１ａ生耐碱性较强的藜科植物。在松嫩平原碱化草甸２个固定的单优碱蓬群落上壤中有活力种子的数量动态和种群动态的研究结果表明：土壤种子库存量在尚未萌发输出以前为最大，角碱蓬群落为２２２６０位／ｍ￣２，翅碱蓬群落为３７２３０粒／ｍ￣２．整个生长季均有种子输出，２群落的种子库存率随着时间呈渐近形式规律地下降。现存植株数量角碱蓬种群以５月上旬最大，为１９４８０株／ｍ￣２．翅碱蓬则在４月上旬最大，为２４４３０株／ｍ￣２。幼苗累积死亡率随着时间角碱蓬种群呈Ｌｏｇｉｓｔｉｃ曲线形式增加，翅碱蓬种群呈单分子曲线形式增加。

uaeda corniculata and S. heteroptera which are two more alkali-resisting and annotinousspecies of herb in Chenopodieceae growing in the alkalized meadow of the Songnen Plain inNortheast China were examined by random sampling on a periodical basis from their twofixed mono-dominant communities to investigate the changes in the storages of their viableseeds in soils and the dynamics of their populations . The results show that the viable seeds insolis have the greatest standing storage immediately before initiating their germinations,i.e. ,of 22260 seeds /m￣2 for S. corniculata and of 37230 seeds/m￣2 for S. heteroptera. Throughoutthe growth season,the seeds are constantly output from the soil seed banks and the storagesin the soil seed banks of both communites are regularly reduced in a variate hyperbolic formwith time, The standing plants have the largest number of 19480 plants/m￣2 for S.corniculata population in the first ten-day period of May and of 24430 plants/m￣2 for S.heteroptera popu-lation in the first ten-day period of April.The accumulative seedling mortality increases byfollowing a logistic curve for S.corniculata population and by following a monomolecularcurve for S. heteroptera population,with time.