Overstory tree measurements from a long-term western larch spacing and thinning study in northwestern Montana, 1961-2015

2021 ◽  
Author(s):  
Danielle F. Hayes ◽  
Michael S. Schaedel ◽  
David K. Wright ◽  
Justin S. Crotteau
Keyword(s):  
Western Larch ◽  
Northwestern Montana ◽  
Overstory Tree

scholarly journals Long-term precommercial thinning effects on Larix occidentalis (western larch) tree and stand characteristics

2017 ◽  
Vol 47 (7) ◽  
pp. 861-874 ◽  
Author(s):  
Michael S. Schaedel ◽  
Andrew J. Larson ◽  
David L.R. Affleck ◽  
R. Travis Belote ◽  
John M. Goodburn ◽  
...  
Keyword(s):  
Tree Growth ◽  
Tree Level ◽  
Recent Measurement ◽  
Larix Occidentalis ◽  
Western Larch ◽  
Individual Tree ◽  
Precommercial Thinning ◽  
Linear Contrasts ◽  
Stand Yield

Precommercial thinning (PCT) is used to increase tree size and shorten harvest rotation time. Short-term results from PCT studies often show a trade-off between individual-tree growth and net stand yield, while longer-term effects of PCT on tree growth and stand yield are less well documented. We used a 54-year-old PCT study to test long-term effects of forest density and thinning schedules on stand yield and tree-level characteristics in even-aged western larch (Larix occidentalis Nutt.) stands. The study has three target densities (494, 890, and 1680 trees·ha−1) crossed with three thinning schedules (target density achieved through one, two, or four entries). Analysis of variance (ANOVA) and linear contrasts were used to test the effects of density and number of entries on tree- and stand-level attributes. Thinning before stand age 10 years leads to long-term constant yield (219.0–269.5 m3·ha−1; P > 0.05) across the tested densities. We also found constant volume growth across stand densities during the most recent measurement interval (5.42–6.41 m3·ha−1·year−1; P > 0.05). Number of entries did not affect any tree- or stand-level attribute. The primary effect of early PCT is to control whether wood volume and growth are concentrated on few large, stable trees or spread over many small, unstable trees.

Population differences in water-use efficiency of well-watered and water-stressed western larch seedlings

1994 ◽  
Vol 24 (1) ◽  
pp. 92-99 ◽  
Author(s):  
Jianwei Zhang ◽  
John D. Marshall
Keyword(s):  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Use ◽  
Dry Matter ◽  
Genotypic Differences ◽  
Dry Matter Accumulation ◽  
Population Differences ◽  
Western Larch ◽  
Use Efficiency

Gas exchange, water-use efficiency (WUE), and carbon-isotope discrimination (Δ) were compared among 14 populations of western larch (Larixoccidentalis Nutt.), a deciduous conifer. Seedlings grown from seed collected across the natural distribution of the species were maintained under water-stressed and well-watered conditions. No differences in gas exchange or instantaneous water-use efficiency (WUEi) were detected among populations. However, population differences in Δ, a second measure of water-use efficiency, were observed. WUE measured as the rate of dry matter accumulation per cumulative water transpired (WUET) was different among populations at the P = 0.07 level. The three measures of WUE were intercorrelated and all were higher among water-stressed seedlings than among well-watered seedlings. Overall means were 4.30 ± 0.08 (± SE) and 3.61 ± 0.07 g dry matter accumulation per kg water transpired (WUET), 2.80 ± 0.09 and 2.02 ± 0.06 μmol CO2 uptake per μmol H2O transpired (WUEi), and Δ was 18.24 ± 0.08‰ and 20.26 ± 0.10‰ under the water-stressed and well-watered treatments, respectively. Population differences in the two integrated measurements, WUET and Δ, were significantly correlated with the altitude at which seed was collected. No interaction between genotype and watering treatment was observed, which means that despite pronounced shifts in WUE between watering treatments, population rankings remained unchanged. These results provide evidence of genotypic differences in long-term measures of WUE among native populations of western larch.

Characteristics and densities of Williamson’s Sapsucker nest trees in British Columbia

2009 ◽  
Vol 39 (12) ◽  
pp. 2319-2331 ◽  
Author(s):  
L. W. Gyug ◽  
C. Steeger ◽  
I. Ohanjanian
Keyword(s):  
British Columbia ◽  
Endangered Species ◽  
Populus Tremuloides ◽  
Stand Structure ◽  
Tree Density ◽  
Trembling Aspen ◽  
Larix Occidentalis ◽  
Western Larch ◽  
Term Maintenance

We characterized Williamson’s Sapsucker ( Sphyrapicus thyroideus (Cassin, 1852)) nest trees in southern British Columbia from 1995 to 2008 to determine the nesting requirements of this endangered species in Canada. In the East Kootenay (n = 32) and the Okanagan (n = 157) regions where western larch ( Larix occidentalis Nutt.) occurred, 81% and 75% of the nest trees were western larch, respectively. In regions west of the Okanagan Valley where western larch did not occur (n = 73), 77% of the nest trees were trembling aspen ( Populus tremuloides Michx.). Conifer nest trees were larger (72 cm DBH), on average, than broad-leaved nest trees (35 cm DBH), and this pattern was consistent across the breeding range of Williamson’s Sapsucker. Live western larch >67 cm DBH with either broken or dead tops were the trees with the highest frequency (20%) among the trees estimated to be suitable for nesting, primarily because these larch tended to be infected with heart rots. Based on observed densities, targets should be 1.36 suitable nest trees/ha in managed stands, although in many instances such as aspen patches, this target will only be met in portions of the nesting territories. The recommended stand structure for long-term maintenance of high nest-tree density in western larch stands is for ≥20 trees/ha with DBHs >57 cm and 60–150 trees/ha with DBHs >22 cm.

Therapy and prevention for mental health: What if mental diseases are mostly not brain disorders?

2019 ◽  
Vol 42 ◽  
Author(s):  
John P. A. Ioannidis
Keyword(s):  
Mental Health ◽  
Mental Disease ◽  
Brain Disorders ◽  
Social Stressors ◽  
Labor Education ◽  
Mental Diseases ◽  
Long Term Follow Up ◽  
Political Decisions

AbstractNeurobiology-based interventions for mental diseases and searches for useful biomarkers of treatment response have largely failed. Clinical trials should assess interventions related to environmental and social stressors, with long-term follow-up; social rather than biological endpoints; personalized outcomes; and suitable cluster, adaptive, and n-of-1 designs. Labor, education, financial, and other social/political decisions should be evaluated for their impacts on mental disease.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Brief summary of Kleť photographic search programme for minor planets

1999 ◽  
Vol 173 ◽  
pp. 189-192
Author(s):  
J. Tichá ◽  
M. Tichý ◽  
Z. Moravec
Keyword(s):  
Ccd Camera ◽  
Minor Planet ◽  
Minor Planets ◽  
Main Belt

AbstractA long-term photographic search programme for minor planets was begun at the Kleť Observatory at the end of seventies using a 0.63-m Maksutov telescope, but with insufficient respect for long-arc follow-up astrometry. More than two thousand provisional designations were given to new Kleť discoveries. Since 1993 targeted follow-up astrometry of Kleť candidates has been performed with a 0.57-m reflector equipped with a CCD camera, and reliable orbits for many previous Kleť discoveries have been determined. The photographic programme results in more than 350 numbered minor planets credited to Kleť, one of the world's most prolific discovery sites. Nearly 50 per cent of them were numbered as a consequence of CCD follow-up observations since 1994.This brief summary describes the results of this Kleť photographic minor planet survey between 1977 and 1996. The majority of the Kleť photographic discoveries are main belt asteroids, but two Amor type asteroids and one Trojan have been found.

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