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Work Package 2c “Mixture configuration” plots

This trial investigated the impact of alternative configurations of broadleaf crop and shelter mixtures. The trial was designed for the medium-term to the point of removal of the shelter species. A number of sites, located throughout the country, were established using species and configurations that exhibit promise from WP2a. A Randomised Complete Block Design was used with six treatments where possible and three replicates. Each trial site that includes all six treatments (see Figure 2) was in excess of 1.5 ha, allowing for open space for access, and enclosed by deer fencing to ensure longevity of the trials. Examples of individual plot designs are provided below (Figure 3). 

Figure 4. Site layout of "Mixture configuration" trial sites


Figure 5. "Mixture configuration" plot designs using oak as an example. Going clockwise starting top left: pure broadleaf crop; alternate lines; 5/3 bands; shelterwells; 3/3 bands

Since the beginning of the project, the recommended spacing for the afforestation of oak was increased from 0.75 m × 2 m to 1.5 m × 2 m. A “mixture configuration” trial was established during the 2012-13 planting season at Teagasc Johnstown Castle Research Centre, Co Wexford that uses the new spacing. The trial is planted with oak (Quercus robur) and birch (Betula pubescens), both from native provenances. The trial has three treatments and three replicates. All trees are planted at 2 m × 1.5 m spacing (3,300 stems/ha). The treatments are:

  1. pure oak control
  2. oak:birch 3:3 banded mixture
  3. shelterwells with 12 m centres and consisting of 9 oak per shelterwell.

See Figure 6.

Figure 6. Mixture configuration trial design planted in Johnstown Castle during 2012-13 planting season. o = oak; b = birch

This trial was monitored and used to investigate whether birch can be a suitable nurse for oak.