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Keywords:

  • Boreal forest;
  • Forest dynamics;
  • Gap dynamics;
  • Regeneration;
  • Succession;
  • Tree population dynamics

Abstract

Questions

Can assumptions of the existence of spatially distinct patches (delineated structurally homogeneous parts of the forest, being either areas consisting of canopy trees or areas without canopy trees but in an early or later regenerative phase) and of directional development over time of the vegetation in such patches, as implied by current theory of storm gap dynamics, be verified by remapping previous study sites?

Location

Natural, unmanaged boreo-nemoral spruce-dominated forest in eastern central Sweden.

Methods

By re-mapping three plots, ca, 50 yr after the first inventory, we studied the structure and dynamics of gaps (patches without canopy tree cover) and major tree populations. The old and new maps allowed us to compare two independent assessments of the forest dynamics: one based on tree population changes and one on changes in gap area over time.

Results

The current population structure could partly be described through the earlier-encountered structures of the different tree populations and consecutive processes of recruitment and mortality. However, the re-mapping exercise showed that spatially delineated patches did not develop directionally over time, nor was their development spatially discrete.

Conclusions

Patch dynamics proceeds in such a way that the fate of a single patch may depend on the development of neighbouring patches. As gaps may partly close or merge into larger gaps, and as gap disappearance rate is a function of actual gap size, performance of an initially delimited patch is largely determined by developments in neighbouring patches and cannot be predicted from its momentary patch characteristics. Consequently, we propose an ‘open matrix model’ to describe the changes in a boreo-nemoral spruce forest, rather than a ‘storm gap dynamics’ model.