Below‐Canopy distribution of photosynthetically active radiation and its relation to seedling growth in a boreal Pinus sylvestris stand

A simulation model was used to predict the spatial distribution of direct and diffuse photosynthetically active radiation below a heterogenous canopy of a Pinus sylvestris stand in eastern Finland. Seedling growth was related to both measured and predicted radiation. The model predicted rather well the overall pattern of radiation distribution beneath the canopy. All the growth parameters of Pinus sylvestris seedlings (height, current height increment and mean height increment) correlated positively with the amount of both measured and predicted radiation. The correlation between seedling growth and irradiance was better for predicted diffuse radiation than for total radiation. This was probably because diffuse radiation, being symmetrically distributed around trees, correlates more strongly than direct radiation with other factors affecting seedling growth.

[1]  W. Platt,et al.  Special Feature: Gaps in Forest Ecology , 1989 .

[2]  Seppo Kellomäki,et al.  Architecture of Scots pine crown. , 1986 .

[3]  Performance of a canopy light interception model for conifer shoots, trees and stands. , 1991, Tree physiology.

[4]  T. Pukkala,et al.  Predicting spatial distribution of direct radiation below forest canopies , 1991 .

[5]  G. Lundeberg,et al.  Studies of root competition in a poor pine forest by supply of labelled nitrogen and phosphorus , 1971 .

[6]  C. M. Britton,et al.  Relationships of photosynthetically active radiation and shortwave irradiance , 1976 .

[7]  D. Matt,et al.  The Distribution of Solar Radiation within a Deciduous Forest , 1977 .

[8]  T. Pukkala,et al.  Effect of crown shape and tree distribution on the spatial distribution of shade , 1987 .

[9]  D. Lieberman,et al.  Forests are Not Just Swiss Cheese: Canopy Stereogeometry of Non‐Gaps in Tropical Forests , 1989 .

[10]  G. Robertson,et al.  Spatial Variability in a Successional Plant Community: Patterns of Nitrogen Availability , 1988 .

[11]  G. Robertson.  Geostatistics in Ecology: Interpolating With Known Variance , 1987 .

[12]  T. Pukkala,et al.  Relationship between radiation interception and photosynthesis in forest canopies: effect of stand structure and latitude , 1989 .

[13]  Juha Lappi,et al.  Radiation Regime and Photosynthesis of Coniferous Stands , 1991 .

[14]  T. Spies,et al.  Light regimes beneath closed canopies and tree-fall gaps in temperate and tropical forests , 1990 .

[15]  Charles D. Canham,et al.  Growth and Canopy Architecture of Shade‐Tolerant Trees: Response to Canopy Gaps , 1988 .

[16]  Timo Pukkala,et al.  Effect of Scots pine seed trees on the density of ground vegetation and tree seedlings. , 1989 .

[17]  P. White,et al.  The Ecology of Natural Disturbance and Patch Dynamics , 1986 .

[18]  P. Kalisz,et al.  Single-Tree Influence on Soil Properties in the Mountains of Eastern Kentucky , 1990 .

[19]  Timo Pukkala,et al.  Simulation of within-tree and between-tree shading of direct radiation in a forest canopy: effect of crown shape and sun elevation , 1989 .

[20]  Photosynthesis of a Scots pine shoot: a comparison of two models of shoot photosynthesis in direct and diffuse radiation fields. , 1992, Tree physiology.

[21]  J. M. Norman,et al.  Partitioning solar radiation into direct and diffuse, visible and near-infrared components , 1985 .