Effects of thinning-induced changes in structural heterogeneity on growth, ingrowth, and mortality in secondary coastal Douglas-fir forests

2015 ◽  
Vol 45 (11) ◽  
pp. 1448-1461 ◽  
Author(s):  
Christian Kuehne ◽  
Aaron R. Weiskittel ◽  
Shawn Fraver ◽  
Klaus J. Puettmann
Keyword(s):  
Species Diversity ◽  
Prediction Models ◽  
Structural Diversity ◽  
Structural Heterogeneity ◽  
Variable Density ◽  
Douglas Fir ◽  
Tree Level ◽  
Spatially Explicit ◽  
Individual Tree ◽  
Diversity Measures

Thinning is believed to accelerate the development of late-successional attributes, thereby enhancing stand structural heterogeneity in young, secondary forests. By making use of a large-scale experiment implemented in 40- to 60-year-old coastal Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) forests, we addressed the following objectives: (i) determine the effect of three thinning treatments on the temporal dynamics (first 11 years after thinning) of key forest structure measures, (ii) evaluate the relationships between spatially explicit structural diversity measures and spatially nonexplicit stand metrics, and (iii) test the relationships between stand structure and observed periodic stand volume growth, ingrowth, and mortality. Treatments consisted of high-density, moderate-density, and variable-density thinnings-from-below, as well as a control. Differences in stand structural heterogeneity between treatments were mostly nonsignificant. However, our results suggest that variable-density stands displayed structural enrichment as tree size and tree species diversity increased throughout the study period as a result of continuous ingrowth of species other than Douglas-fir. Simple spatially nonexplicit metrics could not be used to reliably model spatially explicit structural diversity measures. The inclusion of structural and species diversity measures only rarely improved accuracy of sample plot level growth, ingrowth, and mortality prediction models. Despite the short-term nature of this study, we conclude that variable-density thinning shows promise in increasing structural heterogeneity in young even-aged stands. The inclusion of structural diversity measures in growth and mortality models may be beneficial, but further work is needed to clarify the underlying relationships, particularly at the individual-tree level.

Growth and yield of all-aged Douglas-fir – western hemlock forest stands: a matrix model with stand diversity effects

2005 ◽  
Vol 35 (10) ◽  
pp. 2368-2381 ◽  
Author(s):  
Jingjing Liang ◽  
Joseph Buongiorno ◽  
Robert A Monserud
Keyword(s):  
Species Diversity ◽  
Matrix Model ◽  
The United States ◽  
Douglas Fir ◽  
Growth And Yield ◽  
Western Hemlock ◽  
Permanent Plots ◽  
Forest Stands ◽  
Individual Tree ◽  
Size Diversity

A density-dependent matrix model was developed for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) – western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest stands in the Pacific Northwest of the United States. The model predicted the number and volume of trees for 4 species groups and 19 diameter classes. The parameters were based on species-dependent equations linking individual tree growth, mortality, and stand recruitment to tree and stand characteristics, including stand diversity in terms of tree species and size. The equations were estimated with individual tree and stand data from 2706 permanent plots in western Washington and Oregon, largely from private and state lands, measured twice at an average interval of 10 years. Other things being equal, diameter growth increased slightly with species diversity and decreased with size diversity. Recruitment increased with species diversity and decreased with size diversity. Mortality was independent of species diversity and tended to increase with size diversity. There was practically no relationship between individual tree volume and species or size diversity. The number of trees predicted by the model over the interval between successive inventories was generally unbiased. Long-term predictions with different initial conditions were consistent with standard yield tables and compared favorably with those of the Forest Vegetation Simulator. The model also implied that, independently of its initial condition, an undisturbed stand would eventually reach a steady state dominated by western hemlock more than 1 m in diameter, with few trees of other species and size.

Diversity and productivity of hypogeous fungal sporocarps in a variably thinned Douglas-fir forest

1999 ◽  
Vol 29 (8) ◽  
pp. 1259-1268 ◽  
Author(s):  
Wes Colgan III ◽  
Andrew B Carey ◽  
James M Trappe ◽  
Randy Molina ◽  
David Thysell
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Standing Crop ◽  
Variable Density ◽  
Douglas Fir ◽  
Managed Forests ◽  
Hypogeous Fungi ◽  
Management Techniques ◽  
Crop Biomass ◽  
Comprehensive Study

Although ecosystem management techniques are designed to enhance species diversity in managed forests, no comprehensive study has been conducted to evaluate effects of such techniques on diversity and productivity of hypogeous fungi (truffles). During this study, truffles were collected in a 55- to 65-year-old Douglas-fir forest from March 1993 through December 1995 at approximately 6-week intervals. Half of the stands served as controls, half were assigned a variable density thinning (VDT) treatment. A VDT stand comprised a mosaic of patches thinned to different densities of standing live trees. To further evaluate the effect of harvesting impacts, this mosaic was divided into two thinning categories, lightly thinned and heavily thinned areas. Truffle standing crop varied greatly but generally was highest in spring with a smaller peak in the fall. At least some sporocarps were found year round, with winter having the lowest biomass and species richness. Overall standing crop biomass (over all seasons) was significantly lower in VDT stands compared with control stands. The abundance of Gautieria and Hysterangium species was lower in thinned stands, while Melanogaster species diversity and productivity were highest in these stands.

scholarly journals Comparison of Mature Douglas-Firs’ Crown Structures Developed with Two Quantitative Structural Models Using TLS Point Clouds for Neighboring Trees in a Natural Regime Stand

2019 ◽  
Vol 11 (14) ◽  
pp. 1661 ◽  
Author(s):  
Rong Fang ◽  
Bogdan M. Strimbu
Keyword(s):  
Structural Models ◽  
Branch Length ◽  
Douglas Fir ◽  
Data Availability ◽  
Tree Level ◽  
Fine Scale ◽  
Old Growth ◽  
Individual Tree ◽  
Branch Diameter ◽  
Insertion Angle

The Douglas fir crown structure serves important ecological functions in regulating the ecosystem of the Pacific Northwest (PNW). Mapping and modeling of the Douglas-fir crown has traditionally focused on young plantations or old-growth forests. The crown description in natural regime forests is limited by data availability. Terrestrial laser scanning (TLS) enables the acquisition of crown structural attributes, even in dense forests, at a fine scale. The certical and horizontal distributions of the fine-scale branch attributes, such as branch diameter, branch length, and branch insertion angle, will reflect the crown behaviors towards light resources availability, as a result of neighborhood competition. The main objective of the study is to compare crown structural models of a group of neighboring trees developed with two TLS-based procedures, namely: semi-automatic (Cyclone software) and automatic (TreeQSM) procedures. The estimated crown attributes are the branch diameter, branch length, branch insertion angle, height of branch insertion point, and branch azimuth. The results show that branch azimuth distribution does not differ between TreeQSM and Cyclone for most of the sample trees. However, the TreeQSM and Cyclone identified branches exhibit different distributions of insertion height. A paired t-test indicates no difference between the mean branch diameter of Cyclone and TreeQSM at an individual tree level. However, Cyclone estimated that the branch length and branch insertion angle are 0.49 m and 9.9° greater than the TreeQSM estimates, respectively. Repeat measurements of the analysis of variance (ANOVA) suggest that the height along the stem is an influential factor of the difference between the Cyclone and TreeQSM branch diameter estimates. To test whether TLS-based estimates are within the ranges of the previous observations, we computed the tree crown attributes of second- and old-growth trees using Monte Carlo simulations for diameter at breast height (DBH) class 50–55 cm, 60–65 cm, and 85–105 cm. We found that the crown attributes estimated from both of the TLS-based methods are between the simulated second- and old-growth trees, except for DBH 85–105 cm. The TLS-based crown structural models show increasingly diverse distributions of branch insertion angles and increasing branch exclusion as DBH increases. Cyclone-based crown structural models are consistent with previous studies. However, TreeQSM-based crown structural models omitted a significant number of branches and generated crown structures with reduced plausibility.

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.

scholarly journals An integrated system for modeling tree and stand survival

2017 ◽  
Vol 47 (10) ◽  
pp. 1405-1409 ◽  
Author(s):  
Quang V. Cao
Keyword(s):  
Survival Probability ◽  
Mathematical Structure ◽  
Survival Model ◽  
Integrated System ◽  
Survival Models ◽  
Tree Level ◽  
Individual Tree ◽  
Tree Survival ◽  
Different Levels ◽  
Model Approach

Traditionally, separate models have been used to predict the number of trees per unit area (stand-level survival) and the survival probability of an individual tree (tree-level survival) at a certain age. This study investigated the development of integrated systems in which survival models at different levels of resolution are related in a mathematical structure. Two approaches for modeling tree and stand survival were considered: deriving a stand-level survival model from a tree-level survival model (approach 1) and deriving a tree survival model from a stand survival model (approach 2). Both approaches rely on finding a tree diameter that yields a tree survival probability equal to the stand-level survival probability. The tree and stand survival models from either approach are conceptually compatible with each other but not numerically compatible. Parameters of these models can be estimated either sequentially or simultaneously. Results indicated that approach 2, with parameters estimated sequentially (first from the stand survival model and then from the derived tree survival model), performed best in predicting both tree- and stand-level survival. Although disaggregation did not help improve prediction of tree-level survival, this method can be used when numerical consistency between stand and tree survival is desired.

Canopy disturbances over the five-century lifetime of an old-growth Douglas-fir stand in the Pacific Northwest

2002 ◽  
Vol 32 (6) ◽  
pp. 1057-1070 ◽  
Author(s):  
Linda E Winter ◽  
Linda B Brubaker ◽  
Jerry F Franklin ◽  
Eric A Miller ◽  
Donald Q DeWitt
Keyword(s):  
Pacific Northwest ◽  
Variable Density ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Old Growth ◽  
The Pacific ◽  
History Of ◽  
Horizontal Heterogeneity ◽  
Restoration Strategies

The history of canopy disturbances over the lifetime of an old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stand in the western Cascade Range of southern Washington was reconstructed using tree-ring records of cross-dated samples from a 3.3-ha mapped plot. The reconstruction detected pulses in which many western hemlock (Tsuga heterophylla (Raf.) Sarg.) synchronously experienced abrupt and sustained increases in ringwidth, i.e., "growth-increases", and focused on medium-sized or larger ([Formula: see text]0.8 ha) events. The results show that the stand experienced at least three canopy disturbances that each thinned, but did not clear, the canopy over areas [Formula: see text]0.8 ha, occurring approximately in the late 1500s, the 1760s, and the 1930s. None of these promoted regeneration of the shade-intolerant Douglas-fir, all of which established 1500–1521. The disturbances may have promoted regeneration of western hemlock, but their strongest effect on tree dynamics was to elicit western hemlock growth-increases. Canopy disturbances are known to create patchiness, or horizontal heterogeneity, an important characteristic of old-growth forests. This reconstructed history provides one model for restoration strategies to create horizontal heterogeneity in young Douglas-fir stands, for example, by suggesting sizes of areas to thin in variable-density thinnings.

scholarly journals SISFLOR: A COMPUTATIONAL SYSTEM TO DETERMINE THE OPTIMAL TREE BUCKING

2020 ◽  
Vol 28 ◽  
pp. 192-201
Author(s):  
Rodrigo Freitas Silva ◽  
Marcelo Otone Aguiar ◽  
Mayra Luiza Marques Da Silva ◽  
Gilson Fernandes Da Silva ◽  
Adriano Ribeiro De Mendonça
Keyword(s):  
Optimization Technique ◽  
Wood Products ◽  
Tree Level ◽  
Economic Losses ◽  
Computational System ◽  
Individual Tree ◽  
Optimal Tree ◽  
Cutting Pattern ◽  
Forest Enterprises ◽  
The Individual

A continuously competitive forest market and tied to the demands for wood products promotes the study and development of applications that increase the revenue of the forest enterprises. At harvesting, the cutting pattern (forest assortment) in which the trees are traced is traditionally determined by the experience of the chainsaw operator without using any optimization technique, which may result in economic losses in relation to the commercialized products. In general, there are numerous distinct assortments that can be chosen and hardly processed by a brute-force algorithm. This is the forest assortment problem at the individual tree level with the objetice of maximizing the commercial values of the felled trees. stem-level bucking optimization problem. The aim is to maximize the sales value of harvested trees. Dynamic Programming (DP) is an efficient optimization technique to determine the optimum bucking tree as it significantly reduces the number of calculations to be made. Thus, the objective of this work was to develop a modern and intuitive computational system that is able to find the optimum tree stem bucking through DP to help companies over the bole tracing, therefore, characterizing itself as a tool that supports decision making. After the execution of the system, the optimum assortment is shown by sequentially detailing all products that should be removed from the analyzed bole as well as their respective volumes and revenue.

scholarly journals KEANEKARAGAMAN JENIS VEGETASI MANGROVE DI DESA DUSUN BESAR KECAMATAN PULAU MAYA KABUPATEN KAYONG UTARA

2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Cici Khairunnisa ◽  
Eddy Thamrin ◽  
Hari Prayogo
Keyword(s):  
Species Diversity ◽  
Mangrove Forest ◽  
Avicennia Marina ◽  
Forest Vegetation ◽  
Forest Area ◽  
Tree Level ◽  
Importance Value Index ◽  
Importance Value ◽  
Mangrove Vegetation ◽  
Vegetation Species

The diversity of mangrove vegetation is a community that has different characteristics from other communities. Diversity is an important component in mangrove management, but so far the availability of data related to mangroves is still very minimal, including those related to the species diversity of mangrove forest vegetation in the region. This study aims to obtain data on species diversity of vegetation found in the mangrove forest area of Dusun Besar Village, Pulau Maya District, Kayong Utara Regency. Method used was a combination of path and plot method, and the determination of the location and research path location were carried out using purposive sampling. The results of observation and data analysis showed that the dominant vegetation species with the highest importance value index (INP) for seedlings, saplings and trees was the Avicennia marina, namely the INP value of seedlings 37.04%, the INP values of sapling 65.24%, and the value of INP a tree rate of 65. Based on the results of the most dominant analysis found the species of  Avicennia marina with a value of C = 0.03430 for seedling, C = 0.04729 for sapling, and C = 0.04736 for tree level. The diversity of mangrove forest vegetation species in Dusun Besar Village for seedlings, saplings and trees is low because it has an H 'value <1, and the abundance of mangrove vegetation species was not evenly distributed in each forest area because it only has an e value <1.Keywords: Dusun Besar Village, Mangrove Forest, Species Diversity

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