Abstract
Plantation transformation is a goal of increasing interest to
silviculturalists. The target forest state is characterised by high
variance in age and size, and an irregular spatial structure, which
leads to inhomogeneous interactions between, and consequent
development of, trees in the stand. This presents a difficulty for
traditional methods such as yield tables, and demands a more careful
consideration of stand dynamics. On the other hand, while forestry has
a great heritage of simulation, the level of complexity implemented at
an individual level generally precludes direct understanding of stand
scale behaviours, and leads to difficulties in verification with
appropriate data. A promising approach is the application of
relatively simple models developed by ecologists. These can be adapted
to yield accurate representations of forest stands, while being highly
amenable to analysis. Motivated by data from Scots pine (Pinus
sylvestris L.) stands, we here apply a simple spatial
birth-death-growth model to the comparison and analysis of
transformation strategies for plantation stands. The model captures
the effects of neighbours in a way which retains the conceptual
simplicity of a generic, analytically solvable model, while allowing
insights into the driving factors of population dynamics. Timing and
intensity of management interventions, as opposed to their specific
criteria, are of primary importance: thinnings of a moderate intensity
performed over a long period produced the best results. Variation in
the strategy applied leads to more subtle effects which transformation
strategies must also take into account, such as the development of
variation in size of the remaining trees (increased using spatially
correlated thinnings), the survival chances of regeneration and
"underplanted" trees, and the overall productivity of the stand
(increased using spatially homogeneous crown thinning). Finally, we
demonstrate the robustness of model predictions to fundamental choices
of model formulation.
Year
2011
Category
Refereed journal