Effects of neighbours on crown length of Abies lasiocarpa and Picea engelmannii in two old-growth stands in British Columbia

2010 ◽  
Vol 40 (4) ◽  
pp. 638-647 ◽  
Author(s):  
Joseph A. Antos ◽  
Roberta Parish ◽  
Gordon D. Nigh
Keyword(s):  
British Columbia ◽  
Vertical Structure ◽  
Tree Height ◽  
Picea Engelmannii ◽  
Abies Lasiocarpa ◽  
Crown Architecture ◽  
Mixed Species ◽  
Old Growth ◽  
Crown Length

Crown length is a key aspect of vertical structure in multi-aged, multistrata, mixed-species forests. Crown length, defined as the distance from the tree top to the lowest live branch whorl, was determined for 3169 mapped trees ≥4.0 cm in diameter, in four 0.25 ha plots in each of two old-growth Abies lasiocarpa  (Hook.) Nutt. – Picea engelmannii Parry ex Engelm. stands. We randomly selected half the trees to build models and half for validation. Crown length was modelled as a function of tree height, incorporating modifiers to account for neighbouring trees. The inclusion radius and height threshold for competition were 3 m and 70%, respectively. The addition of two modifiers significantly improved the model for A. lasiocarpa; crown length decreased as the number of neighbours increased and as the height of surrounding trees increased. In contrast, none of the modifiers significantly improved the model for P. engelmannii. Except at high levels of competition, Abies crowns were longer than those of Picea. However, both species in these forests have long crowns, typically three-quarters of the tree height and rarely less than half. The tightly programmed conical crown architecture of these species likely contributes to long crowns and to the limited effects of neighbours on crown length.

Regeneration of Picea engelmannii and Abies lasiocarpa in high-elevation forests of south-central British Columbia depends on nurse logs

2003 ◽  
Vol 79 (2) ◽  
pp. 273-279 ◽  
Author(s):  
Peter Brang ◽  
Jonathan Moran ◽  
Pasi Puttonen ◽  
Alan Vyse
Keyword(s):  
British Columbia ◽  
Strong Dependence ◽  
Picea Engelmannii ◽  
Abies Lasiocarpa ◽  
Old Growth ◽  
Rotten Wood ◽  
South Central ◽  
Advance Regeneration ◽  
Direct Light ◽  
Nurse Logs

We studied the regeneration niche of Picea engelmannii and Abies lasiocarpa in wet sub-zones of the Engelmann spruce-subalpine fir (ESSF) zone of southern British Columbia. We characterized the niche on transects from clearcuts into adjacent old-growth stands, in terms of aspect, elevation, micro-relief, light, seedbed, canopy cover, and competing vegetation. Fourteen transects were sampled at four watersheds. The sampling design ensured similar representation of small (1–30 cm), medium (31–100 cm) and tall (101–300 cm) saplings, and of both species. In total, 465 Picea and 623 Abies saplings were sampled. For every third sapling, an adjacent microsite with no sapling was selected using a random procedure and correspondingly characterized, enabling a pairwise comparison of microsites with and without saplings. Recruitment of both species was related to rotten wood seedbeds, i.e., mainly logs, but also stumps and root plates. This effect was stronger for Picea saplings, and it decreased with increasing sapling size, suggesting lower survival on rotten wood seedbeds. A higher occurrence of tall Abies saplings, in comparison to small ones, under the cover of canopy trees suggests higher survival under canopy than in gaps. Levels of direct light did not generally differ either between microsites with and without regeneration, or between Picea and Abies saplings. The microsite effects on sapling occurrence were quite consistent across gentle south- and north-facing slopes, upper and lower ESSF forests, sites, and along clearcut – old-growth gradients. The results suggest a strong dependence of Picea and Abies establishment on logs in ESSF forests. Key words: seedling establishment, microsite, seedbed, nurse logs, direct light, advance regeneration, ecological niche

Tree crown ratio models for multi-species and multi-layered stands of southeastern British Columbia

2005 ◽  
Vol 81 (1) ◽  
pp. 133-141 ◽  
Author(s):  
Hailemariam Temesgen ◽  
Valerie LeMay ◽  
Stephen J Mitchell
Keyword(s):  
British Columbia ◽  
Predictor Variable ◽  
Basal Area ◽  
Tree Height ◽  
Important Predictor ◽  
Tree Level ◽  
Crown Length ◽  
Growth Equations ◽  
Hardwood Tree ◽  
Variable Measurement

The ratio of live crown length to tree height (crown ratio; CR) is often used as an important predictor variable for tree level growth equations, particularly for multi-species and multi-layered stands. Also, CR indicates tree vigour and can be an important habitat variable. Measurement of CR for each tree can be time-consuming and difficult to obtain in very dense stands and for very tall trees where the base of live crown is obscured. Models to predict CR from size, competition and site variables were developed for several coniferous and one hardwood tree species growing in multispecies and multi-layered forest stands (complex stands) of southeastern British Columbia. Simple correlations indicated the expected relationships of CR decreasing with increasing height, and with increasing competition. A logistic model form was used to constrain predicted CR values to the interval [0,1]. Also, predictors were divided into tree size, stand competition, and site measures, and the contribution of each set of contributors was examined. For all models, height was an important predictor. The stand competition measure, basal area of larger trees, contributed significantly to predicting CR given that crown competition factor was also included as a measure of competition. Logical trends in CR versus size and competition variable groups were reflected by the models; site variable slightly improved predictions for some species. Much of the variability in CR was not accounted for, indicating that other variables are important for explaining CR changes in these complex stands. Key words: crown ratio, multi-species stands, multi-layered stands, basal area of larger trees

Height growth–elevation relationships in subalpine forests of interior British Columbia

1996 ◽  
Vol 72 (2) ◽  
pp. 193-198 ◽  
Author(s):  
K. Klinka ◽  
H. Y. H. Chen ◽  
Q. Wang ◽  
R. E. Carter
Keyword(s):  
British Columbia ◽  
Growth Curves ◽  
Analysis Data ◽  
Site Index ◽  
Height Growth ◽  
Picea Engelmannii ◽  
Abies Lasiocarpa ◽  
Subalpine Fir ◽  
Engelmann Spruce ◽  
Study Species

Stem analysis data from even-aged Engelmann spruce (Picea engelmannii Parry ex Engelm.) and subalpine fir [Abies lasiocarpa (Hook.) Nutt.] stands on zonal sites in the Engelmann Spruce—Subalpine Fir biogeoclimatic zone of British Columbia were used to examine the relationships of site index and height growth and elevation, latitude, and longitude. Elevation and latitude were found to be strongly negatively correlated with site index of both study species. Spruce site index (bh age 50) was predicted to decrease 2.9 m and fir site index 2.5 m with every 100 m and 1° increase in elevation and latitude, respectively; however, (i) site index of both species appeared to decline faster with increasing latitude than elevation, and (ii) decrease appeared to be faster for spruce than for fir. Comparison of height growth curves for stands on zonal and azonal sites with similar site index from different elevations and latitudes suggested that there are probably inconsequential differences between the shape of curves for either species. These findings imply that (i) subalpine fir is better adapted to subalpine boreal climates than Engelmann spruce and (ii) development of polymorphic site index curves for estimating site index of both species may be appropriate. Key words: elevation, latitude, longitude, site index, height growth, Abies lasiocarpa, Picea engelmannii, Engelmann Spruce—Subalpine Fir zone

scholarly journals The Possibility of Using the Chapman–Richards and Näslund Functions to Model Height–Diameter Relationships in Hemiboreal Old-Growth Forest in Estonia

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 184
Author(s):  
Kristi Nigul ◽  
Allar Padari ◽  
Andres Kiviste ◽  
Steffen M. Noe ◽  
Henn Korjus ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Tree Height ◽  
Volume Estimation ◽  
Tree Level ◽  
Mixed Species ◽  
Old Growth ◽  
Single Tree ◽  
Old Growth Forest ◽  
Level Data ◽  
Mixed Species Forest

In light of the difficulties in stand volume estimation of natural forests, we analyzed height–diameter relationships and derived a set of height estimation equations for volume estimation for naturally developing forest ecosystems, using the Järvselja old-growth and the Laeva commercial forest in Estonia as a case study. This contribution presents an approach to model individual tree height–diameter relationships for Scots pine, common aspen, silver and downy birch, Norway spruce, black alder, gray alder, linden species, European ash, Norway maple, deciduous species and coniferous species in multi-size and mixed-species naturally developing stands in Estonia. Single-tree-level data were collected in 2013. Two methods were used to obtain stand-level data: whole surface inventory and partial surface inventory. To model the height–diameter relationship in naturally developed mixed-species forest stands in order to predict single tree height based on observed diameter at breast height, we applied nonlinear mixed models where we applied the Chapman–Richards and Näslund models as fixed-effects and the influence of the species contribution at the sites as random effects. The fixed-effects followed a set of criteria: (1) height starts at h = 1.3; d = 0; (2) the applied functions are monotonically increasing with a clear inflection point and 3) the fixed-effect model has an asymptotic value) in a naturally developed mixed-species forest.

Decay in Advanced Alpine Fir Regeneration in the Kamloops District of British Columbia

1970 ◽  
Vol 46 (3) ◽  
pp. 217-220
Author(s):  
R. B. Smith ◽  
H. M. Craig
Keyword(s):  
British Columbia ◽  
Young Age ◽  
Picea Engelmannii ◽  
Abies Lasiocarpa ◽  
Diameter Class ◽  
Clear Cut ◽  
Advanced Regeneration ◽  
Individual Trees

The extent of decay in alpine fir (Abies lasiocarpa) advanced regeneration in the Kamloops District varied greatly among individual trees, but there was an overall increase in the volume and incidence of decay with increasing diameter and age, even within the same diameter class. Decay was most serious in trees with suspect indicators, of which the most reliable were conks, scars, broken tops and large or numerous branch stubs. The most important decay-causing fungi were Echinodontium tinctorium and Stereum sanguinolentum.Advanced regeneration in clear-cut areas was essentially decay free. This was attributed to the small size and young age of the understory at the time of release, and to the absence of injury from windfalls after logging. Where spruce (Picea engelmannii) — alpine fir stands are not cleanly logged, decay in residual alpine fir may be considerable. To reduce future decay losses, all residual trees over 6 inches dbh, and all smaller alpine fir with conks, broken tops, scars and large or numerous branch stubs should be felled after logging.

scholarly journals IDENTIFICAÇÃO DE ÁRVORES INDIVIDUAIS A PARTIR DE LEVANTAMENTOS LASER AEROTRANSPORTADO POR MEIO DE JANELA INVERSA

CERNE ◽  
2015 ◽  
Vol 21 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Eric Bastos Gorgens ◽  
Luiz Carlos Estraviz Rodriguez ◽  
André Gracioso Peres da Silva ◽  
Carlos Alberto Silva
Keyword(s):  
British Columbia ◽  
Picea Engelmannii ◽  
Abies Lasiocarpa ◽  
Small Footprint

O ponto crucial do filtro de máximos locais é a definição do tamanho da janela. Este trabalho propõe que a janela de busca seja determinada por uma relação inversa à altura do modelo digital de alturas e testa a hipótese de que uma janela de busca, inversamente proporcional, terá melhor desempenho do que a janela de busca proporcional. A área de estudo está localizada na região sudeste do Estado de British Columbia, Canadá. A vegetação natural é do tipo boreal e caracteriza-se pela predominância de duas espécies Picea engelmannii Parry ex. Engelmann (pícea de Engelmann) e Abies lasiocarpa (Hook.) Nutt. (abeto subalpino). O relevo é do tipo ondulado a montanhoso com altitudes que variam de 650 a 2400 metros. Foram lançadas 62 parcelas de campo com 256 metros quadrados. Foi usado um levantamento laser aerotransportado de retornos discretos, com densidade de 2 pontos por metro quadrado e small-footprint. As estimativas foram comparadas aos valores observados em campo durante a medição das parcelas. O desempenho das janelas de busca foi avaliado quanto ao percentual de acertos e quanto ao desvio absoluto. O filtro de máximos locais subestimou o número de árvores por hectare, considerando tanto a janela de busca proporcional quanto a inversamente proporcional. A relação inversa para a determinação da dimensão da janela resultou em melhores resultados, especialmente para regiões com maior densidade de árvores.

scholarly journals Differentiating mature and old-growth forests in the Upper Foothills and Subalpine Subregions of west-central Alberta

2003 ◽  
Vol 79 (3) ◽  
pp. 602-612 ◽  
Author(s):  
Luigi E Morgantini ◽  
John L Kansas
Keyword(s):  
Forest Management ◽  
Growth Index ◽  
Tree Height ◽  
Tree Age ◽  
Old Growth ◽  
West Central ◽  
Decay Class ◽  
Management Area ◽  
Growth Attributes ◽  
Live Tree

Weyerhaeuser Company Ltd. is developing harvest strategies that will maintain appropriate levels of late to very late seral stages ("old growth") in its Drayton Valley Forest Management Area. This management area encompasses 490 570 ha in the Foothills and Rocky Mountain Natural Regions of west-central Alberta. In planning for future forest landscapes, Weyerhaeuser intends to maintain a range of age structures consistent with the ecological processes characteristic of each natural region and subregion. The absence of a discrete point separating mature forest from old growth means that the age at which a stand is currently identified as "old growth" and subject to special management practices is arbitrary. In a research study initiated in the summer of 2000, we seek to understand the differences in structure and composition between forests of various ages and topographic site conditions (elevation, aspect, and slope angle). Using 95 sampling plots in a 123-km2 study area in the Upper Foothills and Subalpine Natural Subregions, we quantified vegetation structure and composition for stands ranging in age from 70 to 300 years. Variables measured and analysed included live-tree height and diameter, snag density, diameter and decay class, downed woody material volume, diameter and decay class, vascular plant species richness, sapling and regeneration density, and duff depth. An old-growth index was developed for each sampled stand that took into account multiple attributes. Preliminary results indicate that specific attributes (snag basal area and density, decay stage and density of downed woody material, variation in live-tree age, and variation in live-tree height and age) separate a younger forest from a more mature one and hence may describe "old-growth" conditions. The age of onset of these old-growth attributes is variable but appears to occur between 160 and 180 years. Key factors other than stand age that contribute to or modify the development of old-growth attributes (as measured by the old-growth index) are elevation and moisture regime (as modified by site position). Further investigation is required to more accurately assess the effect of site factors on old-growth attributes. These results are now used by Weyerhaeuser to address retention of late seral stages in long-term forest planning. Key words: old growth, mature forests, old growth protection, forest management, Alberta, Weyerhaeuser, Rocky Mountains foothills

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