Presentation on theme: "Convergence of Development Phases in a Multi-Aged Primary European Beech Forest at Small Scales Eric K. Zenner 1, Martina L. Hobi 2, Brigitte Commarmot."— Presentation transcript:
Convergence of Development Phases in a Multi-Aged Primary European Beech Forest at Small Scales Eric K. Zenner 1, Martina L. Hobi 2, Brigitte Commarmot 2 1 Penn State University, Univ. Park, PA, USA 2 Swiss Federal Institute for Forest, Snow and Landscape Research WSL Birmensdorf, CH, 19 June 2014
Development Stages and Phases (DS & P) Long history of using DS & P in European primary/old-growth forests Generally 3 stages (i.e., initial or growing up; optimal; decay or breaking down); often 3 phases nested in each stage Stages correspond to the idea of biomass accumulation (sensu Bormann and Likens 1979)
Development Stages and Phases (DS & P) Areas within forests characterized by differences in composition & structure that enable deduction about forest dynamics # canopy stories, dbh dist n, volume, gaps…. Multivariate differences among DS & P
Multi-aged Primary European Beech Forests Small-scale disturbances (gap dynamics) Mosaic of small-scale patches of different DS & P; intimate mixture of phases typical Multi-aged and uneven-sized structures
Multi-aged Primary European Beech Forests Despite the overall “appearance” of primary beech forests (e.g., negative exponential diameter distribution, gaps, large trees), the plenter phase (many- storied structure phase) is thought to be of limited extent and short duration Is this due to the scales at which phases are typically distinguished?
Multi-aged Primeval European Beech Forest of Uholka Located in the Ukrainian Carpathians Part of UNESCO World Heritage site
Multi-aged Primeval European Beech Forest of Uholka Largest primeval beech forest in Europe (>10,000 ha) 10 ha monitoring plot est’d in 2000 (stem-mapped); >95% Eur. beech
Forest Characteristics (2010) Live trees ≥ 6 cm DBH Tree density (N ha -1 )295.9 Basal area (m 2 ha -1 )37.5 Volume (m 3 ha -1 )660.9 Deadwood Tree density (N ha -1 )36.8 Volume (m 3 ha -1 )177.6
Development Phases (adapted from Tabaku 2000) CPA – crown projection area live DS – prop. dead BA NQD – normed quartile distance 100*(75 th –25 th )/ median PSH – prop. stand ht
Development phase Description / Interpretation Gap or regenerationNo regen, canopy cover <30 % EstablishmentDense stands, max DBH <20 cm, mean DBH <16 cm, low growing stock/volume Early optimalDense stands, max DBH ≥20 cm, high increment, increasing growing stock; canopy gaps closing, regen ± missing; phase divided by max DBH (20-40; 41-60; >60 cm) Mid optimal Late optimal PlenterUneven-aged; highly structured; large DBH range TerminalLess structured; high growing stock; age- related mortality; few gaps DecayLow density of large trees; high amount of deadwood; growing stock decreasing; large canopy gaps; increasing vertical structure
Methods Fixed grid cells of increasing areas:
m m m 2
Conclusions Phase assignment appears strongly scale dependent Proportion of the plenter-phase increased steadily with scale At scales ≥625 m 2, only the plenter, terminal, and decay phases (i.e., structurally most complex) remained not an unexpected result under gap dynamics!
Conclusions Convergence to plenter-phase nearly complete at the scale of 1 ha Results are in contrast to other studies that report limited spatial extent of plenter- phase maybe too fine scaled? Context? Does it make sense to distinguish phases of very small extent? If so, to what end? Is a gap = phase?