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.

Evaluating the influence of stem form and damage on individual-tree diameter increment and survival in the Acadian Region: implications for predicting future value of northern commercial hardwood stands

2018 ◽  
Vol 48 (9) ◽  
pp. 1007-1019 ◽  
Author(s):  
Mark Castle ◽  
Aaron Weiskittel ◽  
Robert Wagner ◽  
Mark Ducey ◽  
Jereme Frank ◽  
...  
Keyword(s):  
Growth And Yield ◽  
Tree Level ◽  
Permanent Plots ◽  
Stem Form ◽  
Individual Tree ◽  
Tree Diameter ◽  
Diameter Increment ◽  
Hardwood Species ◽  
Future Value

Northern hardwood species display a variety of forms and defects that can reduce stem quality and complicate their timber management. However, for the most part, growth and yield models do not account for the influence of stem form and damage. This study determined the influence of stem form and damage on growth, survival, and projected future sawlog value among several northern commercial hardwood species. To accomplish this, hardwood trees on 112 permanent plots across three long-term research sites in Maine were assigned stem form and risk classes using a tree classification system developed in New Brunswick. A highly significant influence of stem form and risk on annualized individual-tree diameter increment and survival was found. Inclusion of these equations into a regional growth and yield model highlighted the importance of stem form and defects on long-term simulations as projected stand-level future value was significantly reduced by over 17%, on average (range of 13% to 28%), when compared with projections that did not include that tree-level information. The results highlight the importance of stem form and defects, as well as the need to account for them, in growth and yield applications that assess the forecasted value of commercially important hardwood stands.

Individual-tree growth dynamics of mature Abies alba during repeated irregular group shelterwood (Femelschlag) cuttings

2009 ◽  
Vol 39 (12) ◽  
pp. 2437-2449 ◽  
Author(s):  
Klaus J. Puettmann ◽  
Anthony W. D’Amato ◽  
Ulrich Kohnle ◽  
Jürgen Bauhus
Keyword(s):  
Tree Growth ◽  
Growth Response ◽  
Abies Alba ◽  
Control Treatment ◽  
Silver Fir ◽  
Initial Growth ◽  
Individual Tree ◽  
Growing Conditions ◽  
Individual Trees

This study investigated the individual-tree diameter response of mature silver fir ( Abies alba Mill.) to reproduction harvests (Femelschlag: an irregular group shelterwood method) on six sites in the Black Forest, Germany. On each site, four different treatments were applied, including a control treatment and short-, medium, and long-term regeneration periods aimed at the complete removal of overstory trees within 20, 35, and 50 years, respectively. These treatments created a wide variety of growing conditions for individual trees. Relationships between relative diameter growth and stand-level and neighborhood interaction indices were evaluated. Growing conditions for individual trees in control conditions were best characterized using Lorimer’s index for a 16 m radius neighborhood. Equations predicting tree growth in control stands underpredicted initial growth of trees after harvesting operations, suggesting a release effect that is not captured by postharvest density. This effect was larger for smaller trees and influenced by removal intensity. Growth response to density reductions was also influenced by previous harvests. Our results suggest that the growth response of mature trees to reproduction harvests may become an important consideration when increased emphasis is placed on managing for long-term regeneration periods.

A new method for evaluating forest thinning: growth dominance in managed Pinus resinosa stands

2010 ◽  
Vol 40 (5) ◽  
pp. 843-849 ◽  
Author(s):  
John B. Bradford ◽  
Anthony W. D’Amato ◽  
Brian J. Palik ◽  
Shawn Fraver
Keyword(s):  
Tree Growth ◽  
Basal Area ◽  
Pinus Resinosa ◽  
Growth Patterns ◽  
Red Pine ◽  
New Method ◽  
Stand Age ◽  
Individual Tree ◽  
Individual Tree Growth

Growth dominance is a relatively new, simple, quantitative metric of within-stand individual tree growth patterns, and is defined as positive when larger trees in the stand display proportionally greater growth than smaller trees, and negative when smaller trees display proportionally greater growth than larger trees. We examined long-term silvicultural experiments in red pine ( Pinus resinosa Ait.) to characterize how stand age, thinning treatments (thinned from above, below, or both), and stocking levels (residual basal area) influence stand-level growth dominance through time. In stands thinned from below or from both above and below, growth dominance was not significantly different from zero at any age or stocking level. Growth dominance in stands thinned from above trended from negative at low stocking levels to positive at high stocking levels and was positive in young stands. Growth dominance in unthinned stands was positive and increased with age. These results suggest that growth dominance provides a useful tool for assessing the efficacy of thinning treatments designed to reduce competition between trees and promote high levels of productivity across a population, particularly among crop trees.

Live fast-die young: Scaling CO​2 fertilization effects from leaf to ecosystem levels

2020 ◽  
Author(s):  
Laura Marques ◽  
Ensheng Weng ◽  
Benjamin Stocker
Keyword(s):  
Tree Growth ◽  
Carbon Balance ◽  
Environmental Changes ◽  
Ring Width ◽  
Empirical Support ◽  
Individual Tree ◽  
Positive Effects ◽  
Leaf Level ◽  
Competition For Light

<p>Global environmental changes are rapidly altering the functioning and structure of terrestrial ecosystems.Particularly, rising CO<sub>2</sub> atmospheric concentrations have been reported to increase photosynthesis by increasing carbon assimilation and water-use efficiency. This leaf-level CO<sub>2 </sub>fertilization effect may lead to an increase in the biomass stock in forest stands. However, previous studies argued that an enhanced tree growth rate is associated with a reduction in the longevity of trees, thus reducing the ability of forest biomass to act as carbon sinks over long timescales. In addition, faster growth may lead to an acceleration of self-thinning whereby tree density in the stand is reduced due to progressive mutual shading as tree crowns expand and a resulting increase in shaded individuals’ mortality. Nevertheless, previous results relied on empirical relationships between tree growth rates and longevity, without considering any positive effects of elevated CO​<sub>2 </sub>on individual tree’s carbon balance. Individual-based forest datasets such as tree ring width data and forests inventories have been widely used to monitor long-term changes in forest demography. Yet, the mechanistic underlying these processes remains poorly understood and challenges persist in upscaling from individual measurements to higher level of organization.</p><p>Here, we use a vegetation demography model (LM3-PPA) which simulates vegetation dynamics and biogeochemical processes by explicitly scaling from leaf up to ecosystem level by resolving leaf-level physiology, growth, and height-structured competition for light, using the perfect plasticity approximation (PPA). Using this simulation model, we investigate the links between individual trees’ carbon balance under rising CO<sub>2 </sub>levels, their longevity under alternative mortality parametrizations, and the implications for forest dynamics and self-thinning rates. Inventory data from long-term forest reserves is used to assess empirical support for these simulated links. Specifically, we test the hypothesis of <em>faster growth-earlier death</em> in order to assess forests’ capacity to store carbon under environmental changes. This provides key mechanistic insights to reveal whether increased CO<sub>2 </sub>fertilization on leaf-level photosynthesis positively affects tree’s C balance and thereby reduces the mortality under competition for light in the canopy.</p><p> </p>

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.

scholarly journals Deriving a Tree Growth Model from Any Existing Stand Growth Model

2021 ◽  
Author(s):  
Quang V. Cao
Keyword(s):  
Growth Model ◽  
Tree Growth ◽  
Poor Performance ◽  
Tree Level ◽  
Growth Data ◽  
Tree Model ◽  
Individual Tree ◽  
Tree Survival ◽  
Tree Models ◽  
Level Model

In this study, a new method was developed to derive a tree survival and diameter growth model from any existing stand-level model, without the need for individual-tree growth data. Predictions from the derived tree model are constrained to match number of trees and basal area per ha as outputted by the stand model. The tree models derived from three different stand models were evaluated against a tree model, in both unadjusted and disaggregated forms. For the same stand-level model, the derived tree model outperformed its counterpart, the disaggregated tree model. Furthermore, except for one stand model with poor performance, the tree models derived from the remaining two stand models delivered comparable results to those obtained from the unadjusted tree model. The tree model derived from one stand model even performed slightly better than the unadjusted tree model. This is significant because the coefficients of the unadjusted and disaggregated tree models had to be estimated from tree-level growth data, whereas the derived tree model required no tree growth data at all. The methodology presented in this study should be applicable when there is no ingrowth or recruitment.

scholarly journals The Struggle of Ash—Insights from Long-Term Survey in Latvia

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 340
Author(s):  
Ilze Matisone ◽  
Roberts Matisons ◽  
Āris Jansons
Keyword(s):  
Local Density ◽  
Additive Model ◽  
Tree Height ◽  
Natural Resistance ◽  
Critical Conditions ◽  
Tree Level ◽  
Future Potential ◽  
Genetic And Environmental Factors ◽  
Long Term Survey

The dieback of common ash (Fraxinus excelsior L.) has dramatically decreased the abundance of the species in Europe; however, tolerance of trees varies regionally. The tolerance of trees is considered to be a result of synergy of genetic and environmental factors, suggesting an uneven future potential of populations. This also implies that wide extrapolations would be biased and local information is needed. Survival of ash during 2005–2020, as well as stand- and tree-level variables affecting them was assessed based on four surveys of 15 permanent sampling plots from an eastern Baltic region (Latvia) using an additive model. Although at the beginning of dieback a relatively low mortality rate was observed, it increased during the 2015–2020 period, which was caused by dying of the most tolerant trees, though single trees have survived. In the studied stands, ash has been gradually replaced by other local tree species, though some recruitment of ash was locally observed, implying formation of mixed broadleaved stands with slight ash admixture. The survival of trees was related to tree height and position within a stand (relative height and local density), though the relationships were nonlinear, indicating presence of critical conditions. Regarding temporal changes, survival rapidly dropped during the first 16 years, stabilizing at a relatively low level. Although low recruitment of ash still implies plummeting economic importance of the species, the observed responses of survival, as well as the recruitment, imply potential to locally improve the survival of ash via management (tending), hopefully providing time for natural resistance to develop.

scholarly journals Development and Performance Evaluation of a Very Low-Cost UAV-Lidar System for Forestry Applications

2020 ◽  
Vol 13 (1) ◽  
pp. 77
Author(s):  
Tianyu Hu ◽  
Xiliang Sun ◽  
Yanjun Su ◽  
Hongcan Guan ◽  
Qianhui Sun ◽  
...  
Keyword(s):  
Forest Inventory ◽  
Low Cost ◽  
Canopy Cover ◽  
Tree Height ◽  
Flying Height ◽  
Tree Level ◽  
Forest Site ◽  
Lidar System ◽  
Individual Tree ◽  
Gap Fraction

Accurate and repeated forest inventory data are critical to understand forest ecosystem processes and manage forest resources. In recent years, unmanned aerial vehicle (UAV)-borne light detection and ranging (lidar) systems have demonstrated effectiveness at deriving forest inventory attributes. However, their high cost has largely prevented them from being used in large-scale forest applications. Here, we developed a very low-cost UAV lidar system that integrates a recently emerged DJI Livox MID40 laser scanner (~$600 USD) and evaluated its capability in estimating both individual tree-level (i.e., tree height) and plot-level forest inventory attributes (i.e., canopy cover, gap fraction, and leaf area index (LAI)). Moreover, a comprehensive comparison was conducted between the developed DJI Livox system and four other UAV lidar systems equipped with high-end laser scanners (i.e., RIEGL VUX-1 UAV, RIEGL miniVUX-1 UAV, HESAI Pandar40, and Velodyne Puck LITE). Using these instruments, we surveyed a coniferous forest site and a broadleaved forest site, with tree densities ranging from 500 trees/ha to 3000 trees/ha, with 52 UAV flights at different flying height and speed combinations. The developed DJI Livox MID40 system effectively captured the upper canopy structure and terrain surface information at both forest sites. The estimated individual tree height was highly correlated with field measurements (coniferous site: R2 = 0.96, root mean squared error/RMSE = 0.59 m; broadleaved site: R2 = 0.70, RMSE = 1.63 m). The plot-level estimates of canopy cover, gap fraction, and LAI corresponded well with those derived from the high-end RIEGL VUX-1 UAV system but tended to have systematic biases in areas with medium to high canopy densities. Overall, the DJI Livox MID40 system performed comparably to the RIEGL miniVUX-1 UAV, HESAI Pandar40, and Velodyne Puck LITE systems in the coniferous site and to the Velodyne Puck LITE system in the broadleaved forest. Despite its apparent weaknesses of limited sensitivity to low-intensity returns and narrow field of view, we believe that the very low-cost system developed by this study can largely broaden the potential use of UAV lidar in forest inventory applications. This study also provides guidance for the selection of the appropriate UAV lidar system and flight specifications for forest research and management.

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