京西百花山区植物群落凋落物对土壤种子库的影响

Effects of Litter of Plant Communities on Soil Seed Bank in the Baihua Mountainous Area of West Beijing City

采用种子萌发法对京西百花山区9种植物群落(以草本和灌木植物种子为主)土壤种子库进行了研究。结果显示,不同植物群落土壤种子库储量为97～1224粒/m2,物种数目为9～24种,Simpson指数为0.74～0.93,Margalef指数为1.13～4.42,Shannon—Wiener指数为0.69～0.94。凋落物对土壤种子库的影响体现在两方面。(1)凋落物对土壤种子库的截留,截留率为30.8%～77.3%。通过线性相关分析得出,凋落物对土壤种子库的截留率与凋落物的厚度成正相关。(2)凋落物对土壤种子库萌发幼苗生长的影响(试验中采用种子出苗3个月内死亡率来衡量)。凋落物层较厚的森林群落中,凋落物层幼苗的死亡率高于土层,凋落物层中幼苗的死亡率为11.9%～20.3%,土层中幼苗的死亡率为4.8%～8.3%;而凋落物层较薄的灌木和草本群落中,凋落物层幼苗的死亡率低于土层,凋落物层中幼苗的死亡率为2.6%～4.4%,土层中幼苗的死亡率3.2%～5.1%。凋落物层中幼苗的死亡率与凋落物厚度成正相关。

By seed germination monitoring, transient soil seed bank of nine communities in the Baihua mountainous area of West Beijing City are analyzed. Results showed that the storage capacity of soil seed bank of different vegetation communities ranked from 97 to 1 224 seeds/m^2 ; the number of species, from 9 to 24; Simpson index, from 74 to 0.93; Margalef index, from 1.13 to 42; and Shannon-Wiener, from 0.69 to 94. Effects of litter on soil seed bank were shown in two aspects. First, litter could intercept soil seed bank and the interception rate was between 30.8 % and 77.3 %. Linear correlation analysis revealed that the interception rate had a positive correlation with litter thickness . Second, litter could affect seedling growth （the experiments used mortality of seedling in three months）. In forest communities, mortality of seedling in litter layer （11.9%-20.3%） was higher than that in soil layer （3.2%-8.2%）. In shrub and herb communities, mortality of seedling in litter layer （2.6%-4.4%） was lower than that in soil layer （3.2%-5.1%）. This indicates a significant positive correlation between mortality of seedling in litter layer and litter thickness.