Effect of Stem Snapping on Aspen Timber Assortment Recovery in Hemiboreal Forests

Post-disturbance salvage logging mitigates economic loss after windthrow, and the value of salvaged timber is strongly linked to its quality and dimensions. We studied the occurrence of wind-induced damage of aspen in the hemiboreal forests of Latvia based on data from the National Forest Inventory and additional measurements. Individual tree data from three re-measurement periods were linked to follow a tree condition (live, broken, uprooted) and to link tree characteristics to a respective snag. Three linear models were developed to assess factors affecting the snapping height. An assortment outcome was calculated for undamaged and salvaged trees using the bucking algorithm, and timber value was calculated at three price levels. Wind-induced damage occurred for 3.4–3.6% of aspen trees, and among these, 45.8–46.6% were broken. The mean height of the broken trees was 27.3 ± 0.9 m, and it was significantly higher (both p < 0.01) compared to the height of undamaged and uprooted trees. The tested models indicated tree height as the main explanatory variable for relative snapping height, with higher trees having a lower point of the stem breakage. The other significant factor was the forest type group, indicating that trees growing on dry mineral soils had lower relative snapping height than trees growing on drained mineral soils. Stem breakage significantly (p < 0.001) reduced the volume of assortments, as compared to the volume of undamaged trees. Relative volume loss of sawlogs showed a logarithmic trend with a steep increase up to snapping height of 6 m, and it correlated tightly (r = 0.83, p < 0.001) with relative value loss of the total stem. Timber value loss had a strong, positive relation to tree diameter at breast height and fluctuated by 0.4% among different price levels. The mean volume reduction was 37.7% for sawlogs, 11.0% for pallet blocks, and 8.9% for technological wood.

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Classifying Forest Type in the National Forest Inventory Context with Airborne Hyperspectral and Lidar Data

Remote Sensing ◽

10.3390/rs13101863 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1863

Author(s):

Caileigh Shoot ◽

Hans-Erik Andersen ◽

L. Monika Moskal ◽

Chad Babcock ◽

Bruce D. Cook ◽

...

Keyword(s):

Random Forest ◽

Forest Inventory ◽

Forest Type ◽

Vegetation Indices ◽

National Forest Inventory ◽

Classification Algorithm ◽

Lidar Data ◽

National Forest ◽

Interior Alaska ◽

Type Information

Forest structure and composition regulate a range of ecosystem services, including biodiversity, water and nutrient cycling, and wood volume for resource extraction. Forest type is an important metric measured in the US Forest Service Forest Inventory and Analysis (FIA) program, the national forest inventory of the USA. Forest type information can be used to quantify carbon and other forest resources within specific domains to support ecological analysis and forest management decisions, such as managing for disease and pests. In this study, we developed a methodology that uses a combination of airborne hyperspectral and lidar data to map FIA-defined forest type between sparsely sampled FIA plot data collected in interior Alaska. To determine the best classification algorithm and remote sensing data for this task, five classification algorithms were tested with six different combinations of raw hyperspectral data, hyperspectral vegetation indices, and lidar-derived canopy and topography metrics. Models were trained using forest type information from 632 FIA subplots collected in interior Alaska. Of the thirty model and input combinations tested, the random forest classification algorithm with hyperspectral vegetation indices and lidar-derived topography and canopy height metrics had the highest accuracy (78% overall accuracy). This study supports random forest as a powerful classifier for natural resource data. It also demonstrates the benefits from combining both structural (lidar) and spectral (imagery) data for forest type classification.

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Biomass estimates derived from sector subsampling of 360° spherical images

Forestry An International Journal of Forest Research ◽

10.1093/forestry/cpab023 ◽

2021 ◽

Author(s):

Xiao Dai ◽

Mark J Ducey ◽

Haozhou Wang ◽

Ting-Ru Yang ◽

Yung-Han Hsu ◽

...

Keyword(s):

Basal Area ◽

Sampling Errors ◽

Eastern Canada ◽

Individual Tree ◽

Inventory Costs ◽

Standard Error Estimation ◽

The Mean ◽

Biomass Ratio ◽

Spherical Images ◽

Additional Level

Abstract Efficient subsampling designs reduce forest inventory costs by focusing sampling efforts on more variable forest attributes. Sector subsampling is an efficient and accurate alternative to big basal area factor (big BAF) sampling to estimate the mean basal area to biomass ratio. In this study, we apply sector subsampling of spherical images to estimate aboveground biomass and compare our image-based estimates with field data collected from three early spacing trials on western Newfoundland Island in eastern Canada. The results show that sector subsampling of spherical images produced increased sampling errors of 0.3–3.4 per cent with only about 60 trees measured across 30 spherical images compared with about 4000 trees measured in the field. Photo-derived basal area was underestimated because of occluded trees; however, we implemented an additional level of subsampling, collecting field-based basal area counts, to correct for bias due to occluded trees. We applied Bruce’s formula for standard error estimation to our three-level hierarchical subsampling scheme and showed that Bruce’s formula is generalizable to any dimension of hierarchical subsampling. Spherical images are easily and quickly captured in the field using a consumer-grade 360° camera and sector subsampling, including all individual tree measurements, were obtained using a custom-developed python software package. The system is an efficient and accurate photo-based alternative to field-based big BAF subsampling.

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Mass and nutrient content of woody debris and forest floor in western red cedar and western hemlock forests on northern Vancouver Island

Canadian Journal of Forest Research ◽

10.1139/x93-134 ◽

1993 ◽

Vol 23 (6) ◽

pp. 1052-1059 ◽

Cited By ~ 58

Author(s):

Rodney J. Keenan ◽

Cindy E. Prescott ◽

J.P. Hamish Kimmins

Keyword(s):

Forest Floor ◽

Forest Type ◽

Woody Debris ◽

Nutrient Content ◽

Vancouver Island ◽

Western Hemlock ◽

N Availability ◽

Red Cedar ◽

The Mean ◽

Western Red Cedar

Biomass and C, N, P, and K contents of woody debris and the forest floor were surveyed in adjacent stands of old-growth western red cedar (Thujaplicata Donn)–western hemlock (Tsugaheterophylla (Raf.) Sarg.) (CH type), and 85-year-old, windstorm-derived, second-growth western hemlock–amabilis fir (Abiesamabilis (Dougl.) Forbes) (HA type) at three sites on northern Vancouver Island. Carbon concentrations were relatively constant across all detrital categories (mean = 556.8 mg/g); concentrations of N and P generally increased, and K generally decreased, with increasing degree of decomposition. The mean mass of woody debris was 363 Mg/ha in the CH and 226 Mg/ha in the HA type. The mean forest floor mass was 280 Mg/ha in the CH and 211 Mg/ha in the HA stands. Approximately 60% of the forest floor mass in each forest type was decaying wood. Dead woody material above and within the forest floor represented a significant store of biomass and nutrients in both forest types, containing 82% of the aboveground detrital biomass, 51–59% of the N, and 58–61% of the detrital P. Forest floors in the CH and HA types contained similar total quantities of N, suggesting that the lower N availability in CH forests is not caused by greater immobilization in detritus. The large accumulation of forest floor and woody debris in this region is attributed to slow decomposition in the cool, wet climate, high rates of detrital input following windstorms, and the large size and decay resistance of western red cedar boles.

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Fire history on a desert mountain range: Rincon Mountain Wilderness, Arizona, U.S.A.

Canadian Journal of Forest Research ◽

10.1139/x90-208 ◽

1990 ◽

Vol 20 (10) ◽

pp. 1559-1569 ◽

Cited By ~ 245

Author(s):

Christopher H. Baisan ◽

Thomas W. Swetnam

Keyword(s):

Tree Ring ◽

Large Scale ◽

Fire History ◽

Fire Regime ◽

Forest Type ◽

Drought Severity ◽

Mountain Range ◽

Mixed Conifer ◽

The Mean ◽

Mean Fire Interval

Modern fire records and fire-scarred remnant material collected from logs, snags, and stumps were used to reconstruct and analyze fire history in the mixed-conifer and pine forest above 2300 m within the Rincon Mountain Wilderness of Saguaro National Monument, Arizona, United States. Cross-dating of the remnant material allowed dating of fire events to the calendar year. Estimates of seasonal occurrence were compiled for larger fires. It was determined that the fire regime was dominated by large scale (> 200 ha), early-season (May–July) surface fires. The mean fire interval over the Mica Mountain study area for the period 1657–1893 was 6.1 years with a range of 1–13 years for larger fires. The mean fire interval for the mixed-conifer forest type (1748–1886) was 9.9 years with a range of 3–19 years. Thirty-five major fire years between 1700 and 1900 were compared with a tree-ring reconstruction of the Palmer drought severity index (PDSI). Mean July PDSI for 2 years prior to fires was higher (wetter) than average, while mean fire year PDSI was near average. This 490-year record of fire occurrence demonstrates the value of high-resolution (annual and seasonal) tree-ring analyses for documenting and interpreting temporal and spatial patterns of past fire regimes.

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Variability of throughfall quantity in a mixed evergreen-deciduous broadleaved forest in central China

Journal of Hydrology and Hydromechanics ◽

10.2478/johh-2019-0008 ◽

2019 ◽

Vol 67 (3) ◽

pp. 225-231 ◽

Cited By ~ 2

Author(s):

Lei Su ◽

Zongqiang Xie ◽

Wenting Xu ◽

Changming Zhao

Keyword(s):

Rainfall Intensity ◽

Forest Type ◽

Terrestrial Ecosystem ◽

Rainfall Amount ◽

Central China ◽

Rainfall Characteristics ◽

Evergreen Broadleaved Forest ◽

Transitional Type ◽

The Mean ◽

Spatio Temporal

Abstract Mixed evergreen-deciduous broadleaved forest is the transitional type of evergreen broadleaved forest and deciduous broadleaved forest, and plays a unique eco-hydrologic role in terrestrial ecosystem. We investigated the spatio-temporal patterns of throughfall volume of the forest type in Shennongjia, central China. The results indicated that throughfall represented 84.8% of gross rainfall in the forest. The mean CV (coefficient of variation) of throughfall was 27.27%. Inter-event variability in stand-scale throughfall generation can be substantially altered due to changes in rainfall characteristics, throughfall CV decreased with increasing rainfall amount and intensity, and reached a quasi-constant level when rainfall amount reached 25 mm or rainfall intensity reached 2 mm h−1. During the leafed period, the spatial pattern of throughfall was highly temporal stable, which may result in spatial heterogeneity of soil moisture.

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Retrieving individual tree heights from a point cloud generated with optical imagery from an unmanned aerial vehicle (UAV)

Canadian Journal of Forest Research ◽

10.1139/cjfr-2019-0418 ◽

2020 ◽

Vol 50 (10) ◽

pp. 1012-1024

Author(s):

Meimei Wang ◽

Jiayuan Lin

Keyword(s):

Unmanned Aerial Vehicle ◽

Point Cloud ◽

Laser Scanning ◽

Tree Height ◽

Absolute Error ◽

Coefficient Of Determination ◽

Surface Model ◽

Individual Tree ◽

Aerial Vehicle ◽

The Mean

Individual tree height (ITH) is one of the most important vertical structure parameters of a forest. Field measurement and laser scanning are very expensive for large forests. In this paper, we propose a cost-effective method to acquire ITHs in a forest using the optical overlapping images captured by an unmanned aerial vehicle (UAV). The data sets, including a point cloud, a digital surface model (DSM), and a digital orthorectified map (DOM), were produced from the UAV imagery. The canopy height model (CHM) was obtained by subtracting the digital elevation model (DEM) from the DSM removed of low vegetation. Object-based image analysis was used to extract individual tree crowns (ITCs) from the DOM, and ITHs were initially extracted by overlaying ITC outlines on the CHM. As the extracted ITHs were generally slightly shorter than the measured ITHs, a linear relationship was established between them. The final ITHs of the test site were retrieved by inputting extracted ITHs into the linear regression model. As a result, the coefficient of determination (R2), the root mean square error (RMSE), the mean absolute error (MAE), and the mean relative error (MRE) of the retrieved ITHs against the measured ITHs were 0.92, 1.08 m, 0.76 m, and 0.08, respectively.

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A Comparison of Forest Tree Crown Delineation from Unmanned Aerial Imagery Using Canopy Height Models vs. Spectral Lightness

Forests ◽

10.3390/f11060605 ◽

2020 ◽

Vol 11 (6) ◽

pp. 605 ◽

Cited By ~ 1

Author(s):

Jianyu Gu ◽

Heather Grybas ◽

Russell G. Congalton

Keyword(s):

Spectral Data ◽

Spatial Resolution ◽

Forest Type ◽

Canopy Height ◽

Aerial Imagery ◽

Tree Level ◽

Tree Crown ◽

Remotely Sensed Data ◽

Individual Tree ◽

Tree Crowns

Improvements in computer vision combined with current structure-from-motion photogrammetric methods (SfM) have provided users with the ability to generate very high resolution structural (3D) and spectral data of the forest from imagery collected by unmanned aerial systems (UAS). The products derived by this process are capable of assessing and measuring forest structure at the individual tree level for a significantly lower cost compared to traditional sources such as LiDAR, satellite, or aerial imagery. Locating and delineating individual tree crowns is a common use of remotely sensed data and can be accomplished using either UAS-based structural or spectral data. However, no study has extensively compared these products for this purpose, nor have they been compared under varying spatial resolution, tree crown sizes, or general forest stand type. This research compared the accuracy of individual tree crown segmentation using two UAS-based products, canopy height models (CHM) and spectral lightness information obtained from natural color orthomosaics, using maker-controlled watershed segmentation. The results show that single tree crowns segmented using the spectral lightness were more accurate compared to a CHM approach. The optimal spatial resolution for using lightness information and CHM were found to be 30 and 75 cm, respectively. In addition, the size of tree crowns being segmented also had an impact on the optimal resolution. The density of the forest type, whether predominately deciduous or coniferous, was not found to have an impact on the accuracy of the segmentation.

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Structural Root-Plate Characteristics of Wind-Thrown Norway Spruce in Hemiboreal Forests of Latvia

Forests ◽

10.3390/f11111143 ◽

2020 ◽

Vol 11 (11) ◽

pp. 1143 ◽

Cited By ~ 3

Author(s):

Oskars Krišāns ◽

Valters Samariks ◽

Jānis Donis ◽

Āris Jansons

Keyword(s):

Norway Spruce ◽

Extreme Weather ◽

Extreme Weather Events ◽

Rooting Depth ◽

Peat Soils ◽

Individual Tree ◽

Weather Events ◽

Mineral Soils ◽

Root Plate ◽

Plate Width

An increase in extreme weather events is predicted with increasing climate changes. Changes indicate major problems in the future, as Norway spruce (Picea abies L. Karst.) is one of the most important forestry species in Northern Europe and one of the most susceptible to damage from extreme weather events, like windstorms. Root architecture is essential for tree anchorage. However, information of structural root-plate volume and characteristics in relation to tree wind resistance in drained deep peat soils is lacking. Individual tree susceptibility to wind damage is dependent on tree species, soil properties, tree health and root-plate volume. We assessed the structural root-plate dimensions of wind-thrown Norway spruce on freely drained mineral and drained deep peat soils at four trial sites in Latvia, and root-plate measurements were made on 65 recently tipped-up trees and 36 trees from tree-pulling tests on similar soils. Tree height, diameter at breast height, root-plate width and depth were measured. Measurements of structural root-plate width were done in five directions covering 180° of the root-plate; rooting depth was measured on the horizontal and vertical axes of root-plate. Root-plate volume was higher in drained peat soils in comparison to mineral soils, and root-plate width was the main driver of root-plate volume. A decreasing trend was observed in structural root depth distribution with increasing distance from the stem (i.e., from the center to the edge of the root plate) with a greater decrease in mineral soils.

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A recruitment model for beech–oak pure and mixed stands in Belgium

Forestry An International Journal of Forest Research ◽

10.1093/foresj/cpz056 ◽

2019 ◽

Vol 93 (1) ◽

pp. 124-132

Author(s):

Rubén Manso ◽

Gauthier Ligot ◽

Mathieu Fortin

Keyword(s):

Forest Cover ◽

Forest Type ◽

Growth Models ◽

Geographical Area ◽

National Forest Inventory ◽

Model Parameters ◽

Ecological Knowledge ◽

Mixed Stands ◽

Continuous Forest ◽

Recruitment Model

Abstract We present a recruitment model for pure and mixed beech and oak stands in Belgium, the first empirical model for this forest type in this geographical area. Data from the Wallonia National Forest Inventory were used to fit the model. We adopted a zero-inflated formulation where model parameters governing species’ behaviour were simultaneously fitted. Plot random effects specific to each species were included, the simultaneous fit allowing them to correlate. Model predictions proved accurate and corresponded to current ecological knowledge about the regeneration dynamics of this kind of mixture. While our model could potentially be used to complement the existing beech and oak growth models for this region of Europe, our results also show that beech recruits tend to dominate regardless of the oak share in the overstorey composition and the stand stocking. This confirms that the beech–oak mixture may not be stable under the conditions of the study area and current management aimed at promoting continuous forest cover.

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