Effects of ash and four types of litter on the establishment of Eucalyptus obliqua

We performed a glasshouse experiment to test the effects of ash and four types of litter (leaves and bark of eucalyptus, leaves of Acacia myrtifolia Smith [Willd.], and pine [Pinus radiata D. Don] needles) on the emergence, survival and growth of seedlings of Eucalyptus obliqua L'Herit. Establishment was differentially affected by the various litter types. The effect of position of the seeds (on top or below the litter) depended upon the litter type. Acacia leaves had no effect on seedling emergence, bur increased post-emergence mortality. Pine litter had a positive effect on emergence regardless of the position of the seeds. Eucalypt leaves and bark increased emergence if the seeds were placed underneath the litter, but eucalypt leaves reduced emergence when the seeds were placed on top of it. Ash strongly reduced seedling emergence, and increased mortality independently of the position of the seeds. Seedling biomass was increased by pine needles, and decreased by ash, independently of the placement of the seeds. We measured light interception properties of each of the four types of litter to relate their effects on seedling establishment to their physical properties. Light interception curves followed the expected exponential attenuation. Bark had a lower interception coefficient (per unit of mass) than the other three litter types. However, none of the effects could be correlated to the light interception properties of the different types of litter. The different ground covers affect differentially the establishment of E. obliqua, and have the potential to affect recruitment under field conditions.