GROWTH OF YOUNG SITKA SPRUCE (PICEA-SITCHENSIS (BONG) CARR) AND THE EFFECT OF SIMULATED BROWSING, STAKING AND TREESHELTERS

Sitka spruce (Picea sitchensis (Bong.) Carr.) 1 + 1 transplants were grown at 1 x 1 m for 3 years with 100 per cent chemical weed control on a verv fertile site. Treatments were control, firm staking, staked with 15 cm diameter netting with simulated browsing, staked with simulated browsing to 15 cm diameter clown, 1.2 m treeshelter, 1.2 treeshelter with holes and no browsing. No leaders were browsed. Trees were assessed for annual height growth, stem diameter at 0.5 m and 1.0 m, total above and below ground biomass, root:shoot ratio, root plate diameter, root depth and root volume. No 3-year heights were significantly different but third-year increments were; the greatest final height was in the control at 2.7 cm. All other tree parameters had significant treatment differences demonstrating the need to select carefully the criteria of success in experiments. Treatments which restricted the horizontal development of the canopy either physically or by simulated browsing seriously reduced stem diameter and root development. The controls had a root:shoot ratio of 0.418; treeshelter treatments had the smallest root:shoot ratio of 0.238; staked trees were 0.379 while staked browsed trees had the highest value at 0.447. Acceptance of browsing or use of shelters or guards to protect trees from browsing may seriously reduce growth.