放牧对盐渍化草原植物芦苇繁殖策略的影响

Responses of grazing pressures on asexual and sexual reproduction strategies of Phragmites communis in saline and dry meadow

芦苇Phragmites communis是河西走廊盐渍化草地的主要建群种。近年来由于人类活动及自然灾害等因素的影响,河西走廊的盐渍化草甸草地出现不同程度的退化。研究放牧压力对芦苇种群繁殖策略的影响,探讨芦苇保持最大生存竞争力和抗逆性的机理,对于维护和利用天然草原,保持草地生态系统的稳定具有重要意义。研究结果表明,连续放牧对芦苇地下根茎的生物量影响不显著(P>0.05),芦苇株高显著矮化(P<0.01),地上生物量显著降低(P<0.01),克隆产生的无性系分株显著增加(P<0.05)。连续放牧使得芦苇不能抽穗结实进行有性繁殖。在连续放牧的压力下,芦苇不断产生新的无形系分株,通过无性繁殖成功繁衍自己的后代来延续种群的发展,是对极端生境的一种生态适应对策。

Phragmites communis is one of the dominant species in saline and dry meadow in the Hexi Corridor. The reproductive strategies of P. communis populations were investigated under continuous grazing and no grazing. The results showed that in comparison with the non-grazing, the ramets of P. communis populations were increased with significant difference （P〈0. 05）. On the contrary, the aboveground biomass and plant height were decreased with significant difference （P〈0.01）. The underground biomass and length of roots showed no significant difference （P〉0.05） under continuous grazing.