Long-term patterns of mortality and regeneration in near-natural woodland

Mountford, Edward Peter (2005). Long-term patterns of mortality and regeneration in near-natural woodland. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000d68b

Abstract

1. Long-term patterns of natural regeneration, growth, mortality and disturbance were recorded in six native lowland woods around Britain, using a series of permanent transects/plots established during the 1950-80s. Records were made including the position and status of trees, shrubs, established seedlings, dead wood and canopy gaps.
2. The stands inherited various original-natural features and grew away from a managed state. Nonetheless, their structure and composition remained heavily influenced by past treatment and non-native species.
3. The natural development of five woodland types and twelve tree and shrub species was reviewed and four general stages of stand development were recognised.
4. The major processes controlling stand development were: (i) exclusion; (ii) damage caused by wind, drought, large herbivores and grey squirrels; and (iii) regeneration and release below part-broken stands and within/around larger canopy gaps.
5. The main structural changes identified during stand development were: (i) an increase in basal area to a maximum of c.30-50m² ha^-1; (ii) a decline in stem density until understorey reinitiation/gap-phase regeneration occurred; (iii) an increase instratification, especially under lighter crowned trees and once reinitiation/regeneration occurred; (iv) a scarcity of canopy gaps until at least 125-150 years growth, after which gap creation tended to be patchy and mainly associated with windstorms and drought,though an extensive blow down was recorded; and (v) a scarcity of dead wood until stands matured and broke-up.
6. Compared to other temperate forests, several distinctive aspects of stand development were recognised, particularly: (i) the role of large herbivores in delaying and altering regeneration; (ii) the importance of debarking by grey squirrels; (iii) the potential for some canopy gaps to fill other than with tree regeneration; (iv) the persistence of the understorey in certain native stand types; and (v) the vulnerability of mature beech stands to sudden and quite extensive collapse.