Sapwood area - leaf area relationships for coast redwood

Coast redwood (Sequoia sempervirens (D. Don) End!.) trees in different canopy strata and crown positions were sampled to develop relationships between sapwood cross-sectional area and projected leaf area. Sampling occurred during the summers of 2000 and 2001 and covered tree heights ranging from 7.7 to 45.2 m and diameters at breast height ranging from 9.4 to 92.7 cm. Foliage morphology varied greatly and was stratified into five types based on nee­ dle type (sun or shade) and twig color. A strong linear relationship existed between projected leaf area and sapwood area at breast height or sapwood at the base of the live crown despite the variability in foliage morphology. Ratios of leaf area to sapwood were 0.40 m2tcm2 at breast height and 0.57 m2tcm2 at crown base. Measurements of sapwood at the base of the live crown improved leaf area predictions because of sapwood taper below the crown base. A sapwood taper model was also developed. Resume: Des sequoias cotiers (Sequoia sempervirens (D. Don) End!.) appartenant a differentes strates de couvert et classes sociales ont ete echantillonnes pour etablir des relations entre la superficie d' aubier et la superficie foliaire pro­ jetee. Au cours des etes 2000 et 2001, des arbres de 7,7 a 45,2 m de hauteur et de 9,4 a 92,7 cm de diametre a hau­ teur de poitrine ont ete echantillonnes. La morphologie foliaire variait grandement et a ete stratifiee en cinq groupes se distinguant par Ie type de feuille (lumiere ou ombre) et la couleur des ramilles. La superficie foliaire projetee etait li­ neairement et fortement reliee a la superficie d'aubier a hauteur de poitrine ou a la base de la cime vivante malgre la variabilite de la morphologie foliaire. Les rapports de la superficie foliaire sur la superficie d'aubier etaient de 0,40 m2tcm2 a hauteur de poitrine et de 0,57 m2tcm2 a la base de la cime vivante. Les mesures de superficie d'aubier a la base de la cime vivante ont ameliore les predictions de superficie foliaire en raison du defilement de l'aubier sous la base de la cime. Un modele de defilement de l'aubier a aussi ete mis au point. [Traduit par la Redaction] Introduction width (Albrektson 1984), and other factors. Lower AL:AS with increasing water vapor pressure deficits have been reLeaf area estimates for trees and forest stands provide ported for pines, but not for other conifers (DeLucia et al. useful information for research and management of forest 2000). Species with greater shade tolerance or from more productivity and forest ecosystem analyses. The pipe model mesic environments may also have greater AL:As (Waring et theory imparts biological justification for the use of al. 1982; Margolis et al. 1995) confounding comparisons cross-sectionalsapwoodarea (As) as a surrogatefor leafarea across genera. (AL) (Shinozaki et al. 1964). AL:ASprediction equations have been developed for many conifer species (Waring et al. Coast redwood (Sequoia sempervirens (D. Don) Endl.) is 1982; Vose et al. 1994; Margolis et al. 1995; DeLucia et al. the dominant species in one of the world's most productive 2000). Although these equations have been widely applicaforest ecosystems. No published AL:As relationships exist for ble for a given species, variations exist as a result of mancoast redwood. Given the relatively high shade tolerance of agement history (e.g., thinning, pruning; Brix and Mitchell redwood and its occurrence along California's humid coast, 1983), sapwood permeability (Whitehead et al. 1984), ring a high AL:As would be expected. Waring et al. (1982) sam­ pled a single redwood but did not publish a coefficient. An unpublished Ph.D. dissertation included coefficients of 0.25 Received 6 August 2004. Accepted 23 January 2005. Published on the NRC Research Press Web site at and 0.38 for breast height and crown base AL:As for red­ http://cjfr.nrc.ca on 20 May 2005. wood on the north coast of California (Cavallaro 1989). Leaf area estimation in redwood is complicated by variations in P.T. Stancioiu and K.L. O'Hara.1 Ecosystem Science foliage morphology (Koch et al. 2004): "shade" foliage genDivision, Department of Environmental Science, Policy, and erally consists of flat sprays of two-ranked needles and Management, 145 Mulford Hall, University of California, "sun" foliage consists of shorter, appressed scaled needles Berkeley, CA 94720-3114, USA. that are arranged in several ranks on stems or twigs. Needles lCorresponding author (e-mail: [email protected]). are elliptical in cross-section, whereas stems are cylindrical. Can. J. For. Res. 35: 1250-1255 (2005) doi: 1O.1139/X05-039 @ 2005 NRC Canada 1251 Stancioiu and O'Hara The present study examined sapwood area, leaf area, and foliage morphology of redwood growing in a variety of crown positions in stands located in the middle of the redwood range in California. The objectives were to (i) develop a AL:As relationship for projected leaf area; (ii) develop a model for estimating sapwood area at crown base (ASBLC) from sapwood area at breast height (ASBH); and (iii) categorize and examine distribution of foliage types and projected leaf area. Study area The study area was located within the Jackson Demon­ stration State Forest (39°22'22''N, 123°39'20''W), a 20 OOO-hacoast redwood forest on the California coast in Mendocino County. The climate is Mediterranean, character­ ized by a pattern of high rainfall in winter and cool, dry summers with coastal fog. Precipitation in nearby Caspar Creek watershed averages approximately 130 cm/year. Materials and methods Twelve trees of different size, and from various canopy strata and crown positions (from suppressed to dominant) were sampled in four different second-growth stands during the summers of 2000 and 2001. Trees were classified by crown class and strata following Oliver and Larson (1996). Trees varied in age from approximately 28 to 80 years. Trees of smaller size sampled in the study included suppressed trees in older stands and trees occupying dominant and codominant crown positions in younger stands. Each tree was carefully felled to avoid contact with other crowns and prevent branch loss or mixing of foliage. However, estimates for large trees include some uncertainty about origins of a few branches and foliage on the ground, as some crown damage and (or) mixing occurred during felling. After the tree was felled, total height and crown length were measured to the nearest centimetre. The location of the lowest living vigorous branch defined the base of the live crown. Sum­ mary data for sampled trees are presented in Table I. Crowns were stratified into three sections of equal length. Branches were removed from each section and stratified in two to four different categories based on branch length. Cat­ egories were weighed separately for fresh mass using a spring scale (:t150 g) or an electronic scale (:to.I g) depend­ ing on size. Because some branches were damaged during tree felling, a random branch from each category would not have been representative in most situations. For categories with minor or no damage, branches were selected at random. Where crown damage was more common, a random sample was selected out of the intact branches. The total fresh mass of each of these sample branches was measured and re­ corded. The photosynthetic tissue was then separated from these sample branches and stratified into one of five mor­ phological types: (I) Old shade needles on brown stems older than 2 years, needles easy to detach; (2) Young shade needles with photosynthetic twigs. Twigs up to 2 yearsold.Foliageandtwigs green colored. Twig thin and soft with needles difficult to detach without damaging twig; Table 1. General data for the 12 trees sampled in the study. Total Crown DBH height ratio ASBLC ASBH Statistics (cm) (m) (%) (cm2) (cm2) Mean 31.1 21.1 67 237.97 333.29 SD 25.1 13.4 15 315.66 443.13 Min. 9.4 7.7 43 44.74 53.83 Max. 92.7 45.2 9