The Ratio of Live Crown Length to Sapwood Area as a Measure of Crown Sparseness

Leaf area density is a biologically appealing index of forest tree health because it can provide an assessment of foliage loss or retention; however, it is difficult to measure directly. In contrast, the ratio of crown length to sapwood area (CL:SA) is quite amenable to objective field measurement, and could be interpreted as an index of crown sparseness. CL:SA was computed for Douglas-fir trees from 70 plots covering a range in average size, stand density, site quality, and crown condition in the Oregon Coast Range. When expressed as cm:cm 2 , the index ranged from 2 to 100 for individual trees and from 2 to 11 for plot averages based on the 200 largest trees per ha. In general, individual trees with a high CL:SA had a lower relative height within the stand. The index also increased with increasing severity of needle loss on sites where Swiss needle cast (SNC) is causing premature loss of foliage. After correcting for stand density and stand age, plot basal area growth increased significantly with a decrease in plot average CL:SA across a gradient in Swiss needle cast severity. CL:SA has strong potential for discriminating effectively among stands with varying degrees of foliage loss and growth reduction due to other disturbances as well, such as air pollution and defoliating insects. FOR. SCI. 48(1):93-100.

[1]  Richard H. Waring,et al.  Application of the pipe model theory to predict canopy leaf area. , 1982 .

[2]  C. P. Barnes,et al.  The Structure and Life of Forest Trees , 1930 .

[3]  R. Curtis.  A Simple Index of Stand Density for Douglas-fir , 1982 .

[4]  R. Waring,et al.  Efficiency of Tree Crowns and Stemwood Production at Different Canopy Leaf Densities , 1981 .

[5]  J. Stone,et al.  Incidence and Impact of Swiss Needle Cast in Forest Plantations of Douglas-fir in Coastal Oregon. , 2000, Plant disease.

[6]  K. O’Hara.  Stand structure and growing space efficiency following thinning in an even-aged Douglas-fir stand , 1988 .

[7]  D. Hann,et al.  Height growth rat of Douglas-fir: a comparison of model forms , 1988 .

[8]  R. Horntvedt,et al.  Crown density of spruce trees related to needle biomass , 1993 .

[9]  D. Ostaff,et al.  Patterns of balsam fir foliar production and growth in relation to defoliation by spruce budworm , 1995 .

[10]  H. Margolis,et al.  The adjustment of growth, sapwood area, heartwood area, and sapwood saturated permeability of balsam fir after different intensities of pruning , 1988 .

[11]  T. Kuuluvainen,et al.  Structure and asymmetry of tree crowns in relation to local competition in a natural mature Scots pine forest , 1997 .

[12]  William R. Wykoff,et al.  A Basal Area Increment Model for Individual Conifers in the Northern Rocky Mountains , 1990, Forest Science.

[13]  Richard H. Waring,et al.  Modifying Lodgepole Pine Stands to Change Susceptibility to Mountain Pine Beetle Attack , 1985 .

[14]  D. Maguire,et al.  Sapwood taper models and implied sapwood volume and foliage profiles for coastal Douglas-fir , 1996 .

[15]  Douglas A. Maguire,et al.  The relationship between gross crown dimensions and sapwood area at crown base in Douglas-fir , 1989 .

[16]  J. N. Long,et al.  Influence of stand density on log quality of lodgepole pine , 1988 .

[17]  John L. Innes,et al.  Reliability, presentation, and relationships among data from inventories of forest condition. , 1990 .

[18]  Martin W. Ritchie,et al.  Equations for predicting basal area increment in Douglas-fir and grand fir , 1985 .

[19]  Robert S. Seymour,et al.  Foliage–sapwood area relationships for Abiesbalsamea in central Maine, U.S.A. , 1996 .

[20]  Douglas A. Maguire,et al.  Patterns in vertical distribution of foliage in young coastal Douglas-fir , 1996 .

[21]  John L. Innes,et al.  Forest health surveys: problems in assessing observer objectivity , 1988 .

[22]  D. Hann,et al.  Equations for predicting sapwood area at crown base in southwestern Oregon Douglas-fir , 1987 .

[23]  R. Waring,et al.  Stem Growth per Unit of Leaf Area: A Measure of Tree Vigor , 1980 .

[24]  Chhun-Huor Ung,et al.  Influence of social status on crown geometry and volume increment in regular and irregular black spruce stands , 1996 .

[25]  B. Långström,et al.  Effects of different pruning regimes on growth and sapwood area of Scots pine , 1991 .

[26]  J. N. Long,et al.  Variation in Sapwood Area-Leaf Area Relations Within Two Stands of Lodgepole Pine , 1986 .

[27]  Richard H. Waring,et al.  Tree vigor and stand growth of Douglas-fir as influenced by laminated root rot , 1985 .