内蒙古典型草原不同功能群生产力对凋落物去除的响应

Productivity responses of different functional groups to litter removal in typical grassland of Inner Mongolia

通过对内蒙古典型草原围封23年的样地进行凋落物去除处理后,连续5年的植被调查研究,探讨凋落物对内蒙古典型草原地上生物量的影响及对群落各功能群生物量的影响。研究结果表明,凋落物的不同去除处理对同年植被地上生物量没有显著影响(P>0.05);相同处理不同年际间地上生物量差异显著(P<0.05)。但在处理后的第2年起,草原地上生物量随着凋落物去除程度的增加而增加。凋落物去除对各个功能群生物量的影响表现在处理后的第5年,中度去除条件下的多年生杂类草生物量明显多于重度去除处理和对照区(P<0.05);多年生丛生型禾草在重度处理区的生物量明显高于中度处理区(P<0.05),但二者与对照区均无显著差别(P>0.05);其余各年影响均不显著(P>0.05)。通过对各功能群生物量与总的地上生物量的相关分析得出:在重度去除处理下,地上生物量与禾草的地上生物量相关性较高,多年生杂类草其次。多年生根茎型禾草在中度处理区与地上生物量的相关性最高且显著(P<0.05),其次是一、二年生草本。对照区的多年生丛生型禾草与总地上生物量有显著相关性(P<0.05)。

The objective of this study was to determine whether litter removal affected the above-ground biomass, the relation between above-ground biomass and different functional groups, and to find whether litter can change the structure of plant communities in typical grasslands. The experiments were conducted in October 2002 and three ＇removal＇ treatments were done in typical grassland after they became frozen. There was no significant effect of litter removal on the total above-ground biomass but there was a tendency for the above- ground biomass to increase as the mass of litter removed increased. The effect of litter removal on every differ ent functional group biomass was shown in the 5th year after the removal treatment. The biomass of perennial forbs under the moderate removal treatment was significantly （P〈0.05） higher than that under the heavy removal treatment and in the control plots. Perennial bunch grass under heavy removal treatment had significantly （P〈0.05） higher biomass than that under moderate removal treatment, but there was no difference from the control plot. Analyses of the correlation between total above-ground biomass and each functional group under the same treatment showed that under the heavy removal treatment, the correlation between total grass and total biomass was the closest and that of perennial forbs was second. The biomass of perennial rhizome grass under the moderate removal treatment was significant （P〈0.05） and had the highest correlation with total above-ground biomass. In the control plots, perennial bunch grass had the highest degree of correlation with total above-ground biomass （P〈0.05）.