Sapwood volume for three subalpine conifers: predictive equations and ecological implications

1989 ◽  
Vol 19 (11) ◽  
pp. 1397-1401 ◽  
Author(s):  
Michael G. Ryan
Keyword(s):  
Leaf Area ◽  
Lodgepole Pine ◽  
Maintenance Respiration ◽  
Cross Sectional ◽  
Relative Growth Rates ◽  
Engelmann Spruce ◽  
Rate Of Increase ◽  
Large Trees ◽  
Ray Parenchyma Cells ◽  
The Cost

Xylem conducting tissue or sapwood is an important storage organ for water, carbohydrates, and nutrients, but the living ray parenchyma cells require energy for maintenance. I examined sapwood volume for three subalpine conifers (Engelmann spruce, subalpine fir, and lodgepole pine) in relation to tree size and leaf area. Sapwood volume increases exponentially as leaf area increases, with the rate of increase determined by the ratio of leaf area to sapwood cross-sectional area. Increase in the cost of sapwood maintenance respiration relative to photosynthetic production may explain lower relative growth rates reported for large trees and older stands. Lodgepole pine showed the most rapid increase in sapwood volume with increasing leaf area, suggesting storage capacity and sapwood maintenance are important processes for this species. I also present simple equations for estimating sapwood volume.

Leaf area – sapwood cross-sectional area relationships in repressed stands of lodgepole pine

1987 ◽  
Vol 17 (3) ◽  
pp. 205-209 ◽  
Author(s):  
M. G. Keane ◽  
G. F. Weetman
Keyword(s):  
Hydraulic Conductivity ◽  
Leaf Area ◽  
Wood Density ◽  
Lodgepole Pine ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Density Profiles ◽  
Individual Tree ◽  
Individual Trees

To better understand the phenomenon of growth "stagnation" in high-density lodgepole pine (Pinuscontorta Dougl. ex Loud.), leaf area and its relationship with sapwood cross-sectional area were examined on both an individual tree and stand basis. Leaf areas of individual trees in a 22-year-old stand varied from 30.8 m2 (dominants in stands of low stocking) to 0.05 m2 (suppressed trees in stands of high stocking). Leaf area indices ranged from 13.4 to 2.3 m2 m−2 between low and high stocking levels, respectively. Over the same stocking range, the ratio of leaf area to sapwood cross-sectional area was reduced from 0.3 to 0.15 m2 cm−2. Intraring wood density profiles showed that ovendry density increased from 0.52 to 0.7 g cm−3 and the proportion of early wood decreased over a stocking level range of 6500–109 000 trees/ha. A reduction in hydraulic conductivity in the stems of stagnant trees, suggested by the greater proportion of narrow-diameter tracheids present, may lead to a greater resistance to water transport within the boles of trees from stagnant stands, leading to low leaf areas.

Leaf area and tree increment dynamics of even-aged and multiaged lodgepole pine stands in Montana

1999 ◽  
Vol 29 (6) ◽  
pp. 687-695 ◽  
Author(s):  
Cassandra L Kollenberg ◽  
Kevin L O'Hara
Keyword(s):  
Leaf Area ◽  
Pinus Contorta ◽  
Stand Structure ◽  
Lodgepole Pine ◽  
Stem Volume ◽  
Age Classes ◽  
Cross Sectional ◽  
Individual Tree ◽  
Area Index ◽  
Volume Increment

Age structure and distribution of leaf area index (LAI) of even and multiaged lodgepole pine (Pinus contorta var. latifolia Engelm.) stands were examined on three study areas in western and central Montana. Projected leaf area was determined based on a relationship with sapwood cross-sectional area at breast height. Stand structure and LAI varied considerably between individual plots. LAI and stand stem volume increment were significantly higher in multiaged than even-aged stands with the exception of one study area, which had higher volume increment in even-aged stands. Older cohorts and higher canopy strata generally had greater LAI than younger cohorts and lower strata. Ratios of stem volume increment to leaf area were used to assess stand, cohort, and individual tree vigor or growing space efficiency (GSE). Even-aged stands had significantly higher GSEs in individual study areas and overall than multiaged stands. Cohort GSE generally increased with increasing age of the cohort. Stand increment was weakly associated with stand LAI. Individual tree volume increment was strongly related to projected leaf area when stands were divided by age-classes or canopy strata. These results suggest separating these stands into components, such as age classes or canopy strata, and summing predicted increment for each component may provide more accurate prediction of stand increment than using whole-stand LAI.

Growth and maintenance respiration in stems of Pinuscontorta and Piceaengelmannii

1990 ◽  
Vol 20 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Michael G. Ryan
Keyword(s):  
Cell Volume ◽  
Lodgepole Pine ◽  
Growing Season ◽  
Stem Growth ◽  
Live Cell ◽  
Maintenance Respiration ◽  
Maintenance Costs ◽  
Stem Respiration ◽  
Engelmann Spruce ◽  
Respiratory Behavior

Stem maintenance respiration was linearly related to live-cell volume for lodgepole pine (Pinuscontorta var. latifolia Engelm.) from 4 to 36 cm dbh and for Engelmann spruce (Piceaengelmannii Parry) from 0 to 20 cm dbh. Sapwood contained greater than 80% of the total live-cell volume in stems. Bole surface area, commonly used to estimate tree respiration costs, poorly estimated stem maintenance respiration. At 15 °C, maintenance costs for lodgepole pine were 6.6 × 10−5 kg C•(kg C sapwood)−1•d−1. Stem respiration during the growing season, both corrected and uncorrected for maintenance, correlated well with annual stemwood growth. Annual stem maintenance respiration for trees and stands can be estimated using sapwood volume, sapwood temperature, and knowledge of respiratory behavior. Total respiration (construction plus maintenance) estimated using stem growth and a model of maintenance respiration was compared with actual respiration measurements integrated over a 100-d growing season. Estimated respiration agreed with the integrated measurements for Engelmann spruce, but overestimated the integrated measurements by 73% in lodgepole pine. These results suggest that estimates of stem respiration made during the growing season may be affected by transpiration.

Leaf area - sapwood area relations of lodgepole pine as influenced by stand density and site index

1988 ◽  
Vol 18 (2) ◽  
pp. 247-250 ◽  
Author(s):  
James N. Long ◽  
Frederick W. Smith
Keyword(s):  
Leaf Area ◽  
Forest Ecology ◽  
Lodgepole Pine ◽  
Stand Density ◽  
Site Index ◽  
Site Quality ◽  
Cross Sectional ◽  
Sapwood Area ◽  
Pine Trees ◽  
Stand Conditions

Leaf area to sapwood area ratios for a given species are believed to vary with factors such as site quality, stand density, early stand growth rates, and crown class. Based on data from 55 mature lodgepole pine trees (Pinuscontorta var. latifolia Dougl.) from 10 plots in southeastern Wyoming, we conclude that putative density and site effects on leaf area - sapwood area relations are actually a consequence of the increase in the leaf area to sapwood area ratio with increasing sapwood area. When leaf area is estimated with a nonlinear model that includes tree size and distance to the live crown, the apparent effects of stand density and site index disappear. We consider a constant ratio of leaf area and sapwood cross-sectional area to be inappropriate for the estimation of leaf area aross the range of stand conditions included in most studies of forest ecology.

Genetic variation in tree structure and its relation to size in Douglas-fir. II. Crown form, branch characters, and foliage characters

1994 ◽  
Vol 24 (6) ◽  
pp. 1236-1247 ◽  
Author(s):  
J.B. St. Clair
Keyword(s):  
Genetic Variation ◽  
Leaf Area ◽  
Branch Length ◽  
Douglas Fir ◽  
Projection Area ◽  
Cross Sectional ◽  
Needle Size ◽  
Stem Size ◽  
Large Trees ◽  
Crown Projection Area

Genetic variation and covariation among traits of tree size and structure were assessed in an 18-year-old Douglas-fir (Pseudotsugamenziesii var. menziesii (Mirb.) Franco) genetic test in the Coast Range of Oregon. Considerable genetic variation was found for relative crown width; stem increment per crown projection area; leaf area and branch weight relative to crown size; branch diameter and length adjusted for stem size; branch stoutness; cross-sectional area of branches per crown length; and needle size. Little genetic variation was found for branch numbers per whorl, branch angle, and specific leaf area. At both the phenotypic and genetic level, large trees growing well relative to growing space had tall, narrow crowns, high leaf areas per crown projection area or branch length, greater partitioning to leaves versus branches, and stouter branches. Thus, large, efficient trees were those that invested more in the photosynthetic machinery of leaf area and the branch biomass necessary to support that leaf area, but distributed that leaf area over a greater vertical distance. Unfortunately, these traits also were associated with increased branchiness, and selection for these traits would be accompanied by reductions in harvest index and wood quality.

Evaluating the Outcomes of a Hospital-to-Community Model of Integrated Care for Dementia

2020 ◽  
pp. 1-6
Author(s):  
Ngoc Huong Lien Ha ◽  
Philip Yap Lin Kiat ◽  
Sean Olivia Nicholas ◽  
Ivana Chan ◽  
Shiou Liang Wee
Keyword(s):  
Cost Effectiveness ◽  
Integrated Care ◽  
Dementia Care ◽  
Behavioural Problems ◽  
Gdp Per Capita ◽  
Post Intervention ◽  
Cross Sectional ◽  
Life Years ◽  
Per Capita ◽  
The Cost

<b><i>Introduction:</i></b> Living with dementia is challenging for persons with dementia (PWDs) and their families. Although multi-component intervention, underscored by the ethos of person-centred care, has been shown to maintain quality of life (QOL) in PWDs and caregivers, a lack of service integration can hinder effectiveness. <b><i>Methods:</i></b> CARITAS, an integrated care initiative provided through a hospital-community care partnership, endeavours to provide person-centred dementia care through ambulatory clinic consults, case management, patient and caregiver engagement, and support. We evaluated CARITAS’ clinical outcomes and cost-effectiveness with a naturalistic cross-sectional within-subject design. We assessed patients’ function, QOL, and behavioural problems post-intervention. We estimated CARITAS’ cost-effectiveness from a patient’s perspective, benchmarking it against other dementia treatments and Singapore’s Gross Domestic Product (GDP) per capita. <b><i>Results:</i></b> CARITAS care significantly improved health utility (<i>p</i> &#x3c; 0.001), reduced caregiver burden (<i>p</i> &#x3c; 0.001), and improved PWDs’ behavioural problems (<i>p</i> &#x3c; 0.001) related to “memory” (<i>p</i> &#x3c; 0.001), “disruption” (<i>p</i> = 0.017), and “depression” (<i>p</i> &#x3c; 0.001). CARITAS’ benefits (<i>d</i><sub>RMBPC</sub> = 0.357, <i>d</i><sub>EQ5D index</sub> = 0.328, <i>d</i><sub>ZBI</sub> = 0.361) were comparable to those of other pharmacological and non-pharmacological interventions for dementia. CARITAS costs SG$133,056.69 per quality-adjusted life years gain, yielding an incremental cost-effectiveness ratio of 1.31 and 1.49 against the cost of donepezil in patients with mild Alz­heimer’s disease and Singapore’s GDP per capita in 2019, respectively, falling within the cost-effectiveness threshold of 1.0–3.0. <b><i>Discussion:</i></b> CARITAS integrated dementia care is a cost-effective intervention that showed promising outcomes for PWDs and their caregivers.

scholarly journals Cost-Effectiveness of Colorectal Cancer Genetic Testing

2021 ◽  
Vol 18 (16) ◽  
pp. 8330
Author(s):  
Abdul Rahman Ramdzan ◽  
Mohd Rizal Abdul Manaf ◽  
Azimatun Noor Aizuddin ◽  
Zarina A. Latiff ◽  
Keng Wee Teik ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Genetic Testing ◽  
Cost Effectiveness ◽  
Cancer Survival ◽  
Screening Method ◽  
Targeted Prevention ◽  
Activity Based Costing ◽  
Cross Sectional ◽  
Increased Risk ◽  
The Cost

Colorectal cancer (CRC) remains the second leading cause of cancer-related deaths worldwide. Approximately 3–5% of CRCs are associated with hereditary cancer syndromes. Individuals who harbor germline mutations are at an increased risk of developing early onset CRC, as well as extracolonic tumors. Genetic testing can identify genes that cause these syndromes. Early detection could facilitate the initiation of targeted prevention strategies and surveillance for CRC patients and their families. The aim of this study was to determine the cost-effectiveness of CRC genetic testing. We utilized a cross-sectional design to determine the cost-effectiveness of CRC genetic testing as compared to the usual screening method (iFOBT) from the provider’s perspective. Data on costs and health-related quality of life (HRQoL) of 200 CRC patients from three specialist general hospitals were collected. A mixed-methods approach of activity-based costing, top-down costing, and extracted information from a clinical pathway was used to estimate provider costs. Patients and family members’ HRQoL were measured using the EQ-5D-5L questionnaire. Data from the Malaysian Study on Cancer Survival (MySCan) were used to calculate patient survival. Cost-effectiveness was measured as cost per life-year (LY) and cost per quality-adjusted life-year (QALY). The provider cost for CRC genetic testing was high as compared to that for the current screening method. The current practice for screening is cost-saving as compared to genetic testing. Using a 10-year survival analysis, the estimated number of LYs gained for CRC patients through genetic testing was 0.92 years, and the number of QALYs gained was 1.53 years. The cost per LY gained and cost per QALY gained were calculated. The incremental cost-effectiveness ratio (ICER) showed that genetic testing dominates iFOBT testing. CRC genetic testing is cost-effective and could be considered as routine CRC screening for clinical practice.

Forest structure altered by mountain pine beetle outbreaks affects subsequent attack in a Wyoming lodgepole pine forest, USA

2011 ◽  
Vol 41 (12) ◽  
pp. 2403-2412 ◽  
Author(s):  
Daniel M. Kashian ◽  
Rebecca M. Jackson ◽  
Heather D. Lyons
Keyword(s):  
Pinus Contorta ◽  
Mountain Pine Beetle ◽  
Stand Structure ◽  
Lodgepole Pine ◽  
Climate Change Scenarios ◽  
Cone Production ◽  
Mountain Pine ◽  
Large Trees ◽  
Pine Beetle ◽  
The 1960S

Extensive outbreaks of the mountain pine beetle ( Dendroctonus ponderosae Hopkins) will alter the structure of many stands that will likely be attacked again before experiencing a stand-replacing fire. We examined a stand of lodgepole pine ( Pinus contorta var. latifolia Engelm. ex S. Watson) in Grand Teton National Park currently experiencing a moderate-level outbreak and previously attacked by mountain pine beetle in the 1960s. Consistent with published studies, tree diameter was the main predictor of beetle attack on a given tree, large trees were preferentially attacked, and tree vigor, age, and cone production were unimportant variables for beetle attack at epidemic levels. Small trees killed in the stand were killed based mainly on their proximity to large trees and were likely spatially aggregated with large trees as a result of the previous outbreak. We concluded that the driving factors of beetle attack and their spatial patterns are consistent across outbreak severities but that stand structure altered by the previous outbreak had implications for the current outbreaks in the same location. This study should catalyze additional research that examines how beetle-altered stand structure affects future outbreaks — an important priority for predicting their impacts under climate change scenarios that project increases in outbreak frequency and extent.

scholarly journals Cross-sectional study of prevalence and risk factors, and a cost-effectiveness evaluation of screening and preventive treatment strategies for latent tuberculosis among migrants in Singapore

BMJ Open ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. e050629
Author(s):  
Vanessa W Lim ◽  
Hwee Lin Wee ◽  
Phoebe Lee ◽  
Yijun Lin ◽  
Yi Roe Tan ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cost Effectiveness ◽  
Length Of Stay ◽  
Latent Tuberculosis ◽  
Cross Sectional Study ◽  
Secondary Outcome ◽  
Sectional Study ◽  
Cross Sectional ◽  
Ltbi Prevalence ◽  
The Cost

ObjectivesWHO recommends that low burden countries consider systematic screening and treatment of latent tuberculosis infection (LTBI) in migrants from high incidence countries. We aimed to determine LTBI prevalence and risk factors and evaluate cost-effectiveness of screening and treating LTBI in migrants to Singapore from a government payer perspective.DesignCross-sectional study and cost-effectiveness analysis.SettingMigrants in Singapore.Participants3618 migrants who were between 20 and 50 years old, have not worked in Singapore previously and stayed in Singapore for less than a year were recruited.Primary and secondary outcome measuresCosts, quality-adjusted life-years (QALYs), threshold length of stay, incremental cost-effectiveness ratios (ICERs), cost per active TB case averted.ResultsOf 3584 migrants surveyed, 20.4% had positive interferon-gamma release assay (IGRA) results, with the highest positivity in Filipinos (33.2%). Higher LTBI prevalence was significantly associated with age, marital status and past TB exposure. The cost-effectiveness model projected an ICER of S$57 116 per QALY and S$12 422 per active TB case averted for screening and treating LTBI with 3 months once weekly isoniazid and rifapentine combination regimen treatment compared with no screening over a 50-year time horizon. ICER was most sensitive to the cohort’s length of stay in Singapore, yearly disease progression rates from LTBI to active TB, followed by the cost of IGRA testing.ConclusionsFor LTBI screening and treatment of migrants to be cost-effective, migrants from high burden countries would have to stay in Singapore for ~50 years. Risk-stratified approaches based on projected length of stay and country of origin and/or age group can be considered.

Sign in / Sign up

Export Citation Format

Share Document