Convergence of Development Phases in a Multi-Aged Primary European Beech Forest at Small Scales Eric K. Zenner1, Martina L. Hobi2, Brigitte Commarmot2 1Penn State University, Univ. Park, PA, USA 2Swiss 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 distn, volume, gaps…. Multivariate differences among DS & P Small-scale Multi-aged Primary European Beech Forests 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 (manystoried 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 (m2 ha-1) 37.5 Volume (m3 ha-1) 660.9 Deadwood Tree density (N ha-1) 36.8 Volume (m3 ha-1) 177.6 CPA – crown projection area live DS – prop. dead BA NQD – normed quartile distance 100*(75th–25th)/ median PSH – prop. stand ht Development Phases (adapted from Tabaku 2000) Development phase Description / Interpretation Gap or regeneration No regen, canopy cover <30 % Establishment Dense stands, max DBH <20 cm, mean DBH <16 cm, low growing stock/volume Dense 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) Uneven-aged; highly structured; large DBH range Less structured; high growing stock; agerelated mortality; few gaps Early optimal Mid optimal Late optimal Plenter Terminal Decay Low density of large trees; high amount of deadwood; growing stock decreasing; large canopy gaps; increasing vertical structure Methods Fixed grid cells of increasing areas: Results Results 156.25 m2 625 m2 2500 m2 Conclusions Phase assignment appears strongly scale dependent Proportion of the plenter-phase increased steadily with scale At scales ≥625 m2, 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 plenterphase 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?