Age‐related decline in forest production: modelling the effects of growth limitation, neighbourhood competition and self‐thinning

1 In growing forest stands, above-ground net primary production peaks early in stand development and then declines. The causes for this decline are not yet well understood, but hypotheses include physiological and ecophysiological effects, as well as changes in stand structure due to local competition among neighbouring trees. 2 The majority of existing studies address mono-causal explanations of this decline. Here we study the combined effects of intrinsic growth limitation of individual trees, growth limitation due to neighbourhood competition, and self-thinning. 3 We use an individual-based model to analyse forest wood production of a mangrove species described by a sigmoidal growth function, and two hypothetical species with exponential or linear growth. The model reproduces a decline for all species investigated, even when individual growth rates did not become limited. 4 We conclude that individual, sigmoidal growth curves are sufficient but not necessary to explain the production decline in natural forests where neighbourhood competition is appreciably active. 5 We show that the causes for production decline change during forest development. Whereas growth reduction through neighbourhood competition is the main process at the beginning, imbalanced wood loss dominates the later stage of the decline

[1]  P. W. West.  Model of Above-ground Assimilate Partitioning and Growth of Individual Trees in Even-aged Forest Monoculture , 1993 .

[2]  M. G. Ryan,et al.  Age-related Decline in Forest Ecosystem Growth: An Individual-Tree, Stand-Structure Hypothesis , 2002, Ecosystems.

[3]  Wolfgang Cramer,et al.  A simulation model for the transient effects of climate change on forest landscapes , 1993 .

[4]  D. Binkley.  Response to “Lessons from the Sandbox: Is Unexplained Nitrogen Real?” , 2002, Ecosystems.

[5]  Uta Berger,et al.  Cyclic dynamics in simulated plant populations , 2002, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[6]  H. H. Bartelink,et al.  Effects of stand composition and thinning in mixed-species forests: a modeling approach applied to Douglas-fir and beech. , 2000, Tree physiology.

[7]  K. Kikuzawa.  Self-thinning line and B-point line of the yield-density diagram in a young birch stand , 1993 .

[8]  Uta Berger,et al.  The strength of competition among individual trees and the biomass-density trajectories of the cohort , 2003, Plant Ecology.

[9]  Christopher B. Field,et al.  Tree Mortality in Gap Models: Application to Climate Change , 2001 .

[10]  Benoît Courbaud,et al.  Comparing light interception with stand basal area for predicting tree growth. , 2000, Tree physiology.

[11]  H. Shugart.  A Theory of Forest Dynamics , 1984 .

[12]  Hans Pretzsch,et al.  The single tree-based stand simulator SILVA: construction, application and evaluation , 2002 .

[13]  Annikki Mäkelä,et al.  A carbon balance model of growth and self-pruning in trees based on structural relationships , 1997 .

[14]  H. Shugart.  A Theory of Forest Dynamics , 1984 .

[15]  R. Monserud,et al.  Modeling individual tree mortality for Austrian forest species , 1999 .

[16]  P. Vitousek,et al.  Nitrogen availability and nitrification during succession: Primary, secondary, and old-field seres , 1989, Plant and Soil.

[17]  A. Huth,et al.  The process-based stand growth model Formix 3-Q applied in a GIS environment for growth and yield analysis in a tropical rain forest. , 2000, Tree physiology.

[18]  Michael G. Ryan,et al.  Age-Related Decline in Forest Productivity: Pattern and Process , 1997 .

[19]  Jacob Weiner,et al.  A neighborhood view of interactions among individual plants , 2000 .

[20]  Uta Berger,et al.  A new approach to spatially explicit modelling of forest dynamics: spacing, ageing and neighbourhood competition of mangrove trees , 2000 .

[21]  Harold E. Burkhart,et al.  A stand-level model of carbon allocation and growth, calibrated for loblolly pine , 1997 .

[22]  Jacob Weiner,et al.  The nature of tree growth and the “age‐related decline in forest productivity” , 2001 .

[23]  M. G. Ryan,et al.  Hydraulic Limits to Tree Height and Tree Growth , 1997 .

[24]  R. Twilley,et al.  A gap dynamic model of mangrove forest development along gradients of soil salinity and nutrient resources , 1998 .

[25]  B. Pedersen,et al.  Modeling tree mortality in response to short- and long-term environmental stresses , 1998 .

[26]  Uta Berger,et al.  Asymmetric competition as a natural outcome of neighbour interactions among plants: results from the field-of-neighbourhood modelling approach , 2004, Plant Ecology.

[27]  Michael G. Ryan,et al.  Declining forest productivity in aging forest stands: a modeling analysis of alternative hypotheses. , 1996, Tree physiology.

[28]  Risto Sievänen,et al.  Application of volume growth and survival graphs in the evaluation of four process-based forest growth models. , 2000, Tree physiology.

[29]  S. Gower,et al.  Aboveground net primary production decline with stand age: potential causes. , 1996, Trends in ecology & evolution.

[30]  T. Kira,et al.  PRIMARY PRODUCTION AND TURNOVER OF ORGANIC MATTER IN DIFFERENT FOREST ECOSYSTEMS OF THE WESTERN PACIFIC , 1967 .