Conversion of total to projected leaf area index in conifers

2000 ◽  
Vol 78 (4) ◽  
pp. 447-454 ◽  
Author(s):  
Hugh J Barclay ◽  
Doug Goodman
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Pinus Contorta ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Thuja Plicata ◽  
Area Index ◽  
Conversion Factors ◽  
Horizontal Orientation ◽  
Thuja Plicata Donn

Several definitions of leaf area index (LAI) presently exist in the literature but the relationships among them are not clear. To compare the results of various studies, there is a need to convert from one definition to another. Factors for converting among four definitions of LAI are presented for six conifer species: Abies grandis (Dougl. ex D. Don) Lindl., Thuja plicata Donn ex D. Don., Tsuga heterophylla (Raf.) Sarg., Picea sitchensis (Bong.) Carr.), Pinus contorta Dougl., and Pseudotsuga menziesii (Mirb) Franco). Among the four definitions of LAI, the two extremes involve (i) the total area of the leaf and (ii) the projected area of nonhorizontal leaves, as they occur on the tree. If leaves are randomly oriented in space, then the conversion factor between definitions i and ii should be 0.25. Four of the six species have conversion factors very close to this value, and three of these four are relatively shade-intolerant,. The remaining two species, A. grandis and Thuja plicata, have conversion factors of approximately 0.35, owing to the approximately horizontal orientation of their leaves. These two species are both relatively shade-tolerant, and the trend toward horizontal leaves might be an adaptation to assist in shade tolerance. A sensitivity analysis indicated that the foliage of most of the species maximized the amount of light gathered when the light was coming from almost straight overhead, as is the case with many shaded forest trees.Key words: leaf area index, conifers, leaf area index conversion.

Distribution of leaf orientations in six conifer species

2001 ◽  
Vol 79 (4) ◽  
pp. 389-397 ◽  
Author(s):  
Hugh J Barclay
Keyword(s):  
Pseudotsuga Menziesii ◽  
Pinus Contorta ◽  
Goodness Of Fit ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
The Other ◽  
Thuja Plicata ◽  
Leaf Angle ◽  
Conifer Species ◽  
Abies Grandis

Leaf angle distributions are important in assessing both the flexibility of a plant's response to differing daily and seasonal sun angles and also the variability in the proportion of total leaf area visible in remotely sensed images. Leaf angle distributions are presented for six conifer species, Abies grandis (Dougl. ex D. Don) Lindl., Thuja plicata Donn. ex D. Don, Tsuga heterophylla (Raf.) Sarg., Pseudotsuga menziesii (Mirb.) Franco, Picea sitchensis (Bong.) Carr. and Pinus contorta Dougl. ex Loud. var. latifolia. The leaf angles were calculated by measuring four foliar quantities, and then the distributions of leaf angles are cast in three forms: distributions of (i) the angle of the long axis of the leaf from the vertical for the range 0–180°; (ii) the angle of the long axis of the leaf for the range 0–90°; and (iii) the angle of the plane of the leaf for the range 0–90°. Each of these are fit to the ellipsoidal distribution to test the hypothesis that leaf angles in conifers are sufficiently random to fit the ellipsoidal distribution. The fit was generally better for planar angles and for longitudinal angles between 0° and 90° than for longitudinal angles between 0° and 180°. The fit was also better for Tsuga heterophylla, Pseudotsuga menziesii, Picea sitchensis, and Pinus contorta than for Abies grandis and Thuja plicata. This is probably because Abies and Thuja are more shade tolerant than the other species, and so the leaves in Abies and Thuja are preferentially oriented near the horizontal and are much less random than for the other species. Comparisons of distributions on individual twigs, whole branches, entire trees, and groups of trees were done to test the hypothesis that angle distributions will depend on scale, and these comparisons indicated that the apparent randomness and goodness-of-fit increased on passing to each larger unit (twigs up to groups of trees).Key words: conifer, leaf angles, ellipsoidal distribution.

Leaf area index of an old-growth Douglas-fir forest estimated from direct structural measurements in the canopy

2000 ◽  
Vol 30 (12) ◽  
pp. 1922-1930 ◽  
Author(s):  
Sean C Thomas ◽  
William E Winner
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Understory Vegetation ◽  
Western Hemlock ◽  
Old Growth ◽  
Area Index ◽  
Contact Frequency ◽  
Canopy Access

Leaf area index (LAI) in old-growth Douglas-fir (Pseudotsuga menziesii var menziesii (Mirb.) Franco) forests exceeds that of any other forest ecosystem by some estimates; however, LAI determinations in coniferous forests have generally been indirect, involving extrapolations of patterns observed in younger stands. Aided by a 75-m construction crane for canopy access, we used a vertical line-intercept method to estimate LAI for a [Formula: see text]450-year-old Douglas-fir - western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest in southwestern Washington state. LAI was calculated as the product of foliage contact frequency and an "extinction coefficient" accounting for foliage angular distribution, geometry, and the ratio of "interceptable" to total leaf area. LAI estimates were 9.3 ± 2.1 (estimate ± 95% confidence interval), 8.5 ± 2.2, and 8.2 ± 1.8 in 1997, 1998, and 1999, respectively, or 8.6 ± 1.1 pooled across years. Understory vegetation, including foliage of woody stems <5 cm diameter, represented 20% of this total. Sample points in which Douglas-fir was dominant had a higher total LAI than points dominated by western hemlock, including a higher LAI of understory vegetation. Our results do not support the contention that old-growth Douglas-fir - western hemlock forests maintain an appreciably higher LAI than do other forest ecosystems. Moreover, LAI in very old stands may decline as western hemlock replaces Douglas-fir through the course of succession.

A 14,000 year vegetation history of a hypermaritime island on the outer Pacific coast of Canada based on fossil pollen, spores and conifer stomata

2012 ◽  
Vol 78 (3) ◽  
pp. 572-582 ◽  
Author(s):  
Terri Lacourse ◽  
J. Michelle Delepine ◽  
Elizabeth H. Hoffman ◽  
Rolf W. Mathewes
Keyword(s):  
Pinus Contorta ◽  
Vegetation History ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Thuja Plicata ◽  
North Coast ◽  
Pollen Record ◽  
The North ◽  
History Of ◽  
Local Species

AbstractPollen and conifer stomata analyses of lake sediments from Hippa Island on the north coast of British Columbia were used to reconstruct the vegetation history of this small hypermaritime island. Between 14,000 and 13,230 cal yr BP, the island supported diverse herb–shrub communities dominated by Cyperaceae, Artemisia and Salix. Pinus contorta and Picea sitchensis stomata indicate that these conifers were present among the herb–shrub communities, likely as scattered individuals. Transition to open P. contorta woodland by 13,000 cal yr BP was followed by increases in Alnus viridis, Alnus rubra and P. sitchensis. After 12,000 cal yr BP, Pinus-dominated communities were replaced by dense P. sitchensis and Tsuga heterophylla forest with Lysichiton americanus and fern understory. Thuja plicata stomata indicate that this species was present by 8700 cal yr BP, but the pollen record suggests that its populations did not expand to dominate regional rainforests, along with Tsuga and Picea, until after 6600 cal yr BP. Conifer stomata indicate that species may be locally present for hundreds to thousands of years before pollen exceed thresholds routinely used to infer local species arrival. When combined, pollen and conifer stomata can provide a more accurate record of paleovegetation than either when used alone.

Postglacial vegetation history of Mitkof Island, Alexander Archipelago, southeastern Alaska

2010 ◽  
Vol 73 (2) ◽  
pp. 259-268 ◽  
Author(s):  
Thomas A. Ager ◽  
Paul E. Carrara ◽  
Jane L. Smith ◽  
Victoria Anne ◽  
Joni Johnson
Keyword(s):  
Pinus Contorta ◽  
Vegetation History ◽  
Regional Climate ◽  
Sitka Spruce ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Thuja Plicata ◽  
Pollen Record ◽  
Coastal Forests ◽  
History Of

An AMS radiocarbon-dated pollen record from a peat deposit on Mitkof Island, southeastern Alaska provides a vegetation history spanning ∼12,900 cal yr BP to the present. Late Wisconsin glaciers covered the entire island; deglaciation occurred > 15,400 cal yr BP. The earliest known vegetation to develop on the island (∼12,900 cal yr BP) was pine woodland (Pinus contorta) with alder (Alnus), sedges (Cyperaceae) and ferns (Polypodiaceae type). By ∼12,240 cal yr BP, Sitka spruce (Picea sitchensis) began to colonize the island while pine woodland declined. By ∼11,200 cal yr BP, mountain hemlock (Tsuga mertensiana) began to spread across the island. Sitka spruce-mountain hemlock forests dominated the lowland landscapes of the island until ∼10,180 cal yr BP, when western hemlock (Tsuga heterophylla) began to colonize, and soon became the dominant tree species. Rising percentages of pine, sedge, and sphagnum after ∼7100 cal yr BP may reflect an expansion of peat bog habitats as regional climate began to shift to cooler, wetter conditions. A decline in alders at that time suggests that coastal forests had spread into the island's uplands, replacing large areas of alder thickets. Cedars (Chamaecyparis nootkatensis, Thuja plicata) appeared on Mitkof Island during the late Holocene.

scholarly journals British Columbia Vegetation and Climate History with Focus on 6 ka BP

2007 ◽  
Vol 49 (1) ◽  
pp. 55-79 ◽  
Author(s):  
Richard J. Hebda
Keyword(s):  
British Columbia ◽  
Pinus Contorta ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Early Holocene ◽  
Thuja Plicata ◽  
Quercus Garryana ◽  
Climate History ◽  
The North ◽  
Vegetation And Climate

ABSTRACT British Columbia Holocene vegetation and climate is reconstructed from pollen records. A coastal Pinus contorta paleobiome developed after glacier retreat under cool and probably dry climate. Cool moist forests involving Picea, Abies, Tsuga spp., and Pinus followed until the early Holocene. Pseudotsuga menziesii arrived and spread in the south 10 000-9000 BP, and Picea sitchensis - Tsuga heterophylla forests developed in the north. T. heterophylla increased 7500-7000 BP, and Cupressaceae expanded 5000-4000 BP. Bogs began to develop and expland. Modern vegetation arose 4000-2000 BP. There were early Holocene grass and Artemisia communities at mid-elevations and pine stands at high elevations in southern interior B.C. Forests expanded downslope and lakes formed 8500-7000 BP. Modern forests arose 4500-4000 BP while lower and upper tree lines declined. In northern B.C. non-arboreal communities preceded middle Holocene Picea forests. Abies, Pinus and Picea mariana predominated at various sites after 4000 BP. At 6000 BP Tsuga heterophylla (south) and Picea sitchensis (north) dominated the coast and islands and Quercus garryana and Pseudotsuga on southeast Vancouver Island, but Thuja plicata was infrequent. Southern Interior Plateau vegetation at 6000 BP was more open than today at middle to lower elevations, whereas forests covered the Northern Interior Plateau. Picea forests occurred in northern B.C. Holocene climate phases were: 1) warm dry "xerothermic" ca. 9500-7000 BP, 2) warm moist "mesothermic" ca. 7000-4500 BP, 3) moderate and moist 4500-0 BP, with increasing moisture 8500-6000 BP and cooling (?increased moisture) 4500-3000 BP. B.Cs Hypsithermal had dry and wet stages; 6000 BP occurred in the warm and wet mesothermic stage.

Sign in / Sign up

Export Citation Format

Share Document