The effect of cultivation technique on root and shoot biomass production by young Sitka spruce (Picea sitchensis (Bong.) Carr.) trees on surface water gley soils

In Ireland much of the land available for plantation establishment requires some degree of soil cultivation and drainage to improve its suitability for tree growth. The method of cultivation and drainage normally varies depending upon the soil type and its drainage characteristics. Little research has been carried out on the impact of practices such as mounding and mole drainage upon rooting and biomass production in young crops. The research reported in this paper was carried out on four sites where the general soil type was surface water gley. Three of the sites studied were afforestations on old farmland, while the fourth site was a reforestation of a windblown stand. The cultivation methods investigated included mounding, mole drainage with mounds, mole drainage only and ripping. Sitka spruce trees ranging in age from five to thirty years were excavated from these experimental sites to describe the impact of different soil cultivation techniques upon root architecture and above and below ground biomass production. The results showed that while the effect of mound drainage upon water table level varied from site to site, the establishment of trees on mounds led to an increase in above and below ground biomass production. Mole drainage of these sites without mounds, did not lead to any increase in root or shoot development when compared with trees growing on uncultivated/undrained ground. This revised version was published online in June 2006 with corrections to the Cover Date.