Growth and Biomass Allocation Patterns of Eight Young Sitka . Spruce Clones. Liam Donnelly. 1. , Olga M. Grant. 1. , David Thompson. 2. , Conor O'Reilly. 1.
Growth and Biomass Allocation Patterns of Eight Young Sitka . Spruce Clones Liam Donnelly
1,
Olga M. Grant
1,
David Thompson
2,
Conor O’Reilly
1
1
U.C.D., School of Agriculture & Food Science, Belfield, Dublin 4, Ireland 2 Coillte Research Station, Kilmacurra Park, Kilbride, Co. Wicklow, Ireland Introduction Sitka spruce (Picea sitchensis (Bong.) Carr.) is the dominant forestry species in Ireland. Improved clonal material is now available, which has meant that greater gains in productivity are now possible. However, there is little information on the optimum strategy for the deployment of clonal material. Clones may be deployed in two principal modes: multi-clonal mixtures or monoclonal blocks. The standard approach to field experiments is to use single tree plots which can result in superior clones being over looked (Sharma et al 2008). Each mode of deployment creates a different competitive environment which directly influences tree behaviour (Gould et al. 2011). Thus an understanding of responses to deployment mode is crucial when assessing productivity potential of clones in terms of growth and biomass allocation patterns. Materials and Methods The growth and biomass allocation of eight different Sitka spruce clones from four different full-sibling families were studied during their first growing season in a farm-forestry trial. Trees were planted in closely spaced monoclonal and multi-clonal mixtures (Fig. 1). The experiment was designed as a completely randomized block design with five replicates in blocks of four trees of each clone. Five trees from each clone, in either deployment type, were destructively harvested in February 2014.
Objectives Determine the most productive clones
Assess the impact of different deployment modes on crown traits and biomass allocation
Results Crown morphology differed among clones (Fig. 2). Clone and deployment effects were largest for crown area (Fig. 3a), stem dry mass (Fig. 3b) and lateral root spread (Fig. 3c). Crown area was significantly larger in mixed plots for all clones except clone 5. Clone 8 had the largest crown in both deployment modes. Stem mass was significantly larger in mixed plots for all clones except clone 2. Clone 8 also had the largest stem mass in both deployment modes.
Figure 1. An example of one set of eight mono-clonal and two mixture plots.
C***, D*** a)
Figure 2. Typical crown morphology of four clones in monoclonal plots.
C***, C***, D** D** b) b)
C*** c)
Figure 3. Crown area (a), stem dry mass (b) and lateral root spread (c) respectively (± standard error) for each clone by deployment mode. C, Clone; D, Deployment ***, P
