Analyzing Leaf Clumping Effect of Individual Trees Based on Modeled Realistic Structure

Although selection forests have clear advantages over age-group forests in view of their total growth performance, their net product and their stability, not to mention the sustainability of their beneficial effect, the proportion of this type of forest is insignificantly small in Germany and also in mixed forest in the mountains. It is therefore all the more surprising that scarcely any discernable efforts have been made to increase the proportion of selection forests. For a conversion, an alternative model for the treatment of the stands is adopted, whereby it is no longer the encouragement of the growth to maturity of individual trees in the stand which is aimed for, but rather the transformation of the whole stand to a selection forest using available stand elements and elements created by an early initiation of regeneration. Based on his experience in the forestry district of Kirchzarten in the Black Forest, Germany, the author describes the procedure for a successful conversion. This is to be started as soon as possible, that is to say when the crown height of the trees is about 18 metres and with corresponding usable dimensions, using small group shelter-wood cuts, a so-called initial femel cut. To get the conversion started it is advisable to remove whole groups of predominantly badly situated and overgrown trees. The stand will be additionally structured later through further interventions at short intervals. In the process, here and there really well situated trees will actually be left to stand solitar y, in other places w hol e self-cont aine d groups will b e created and else where valuabl e mixed s tand elements will be selected for permanent preservation, this in order to create a situation in which there are about 35 overstorey trees per hectare. On the basis of his own cost calculations, the author comes to the conclusion that the conversion is, from a financial point of view, superior compared with the age-group forest in that it brings higher proceeds more quickly and more often.

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Update on the Boundaries of the Curly Birch Range

Lesnoy Zhurnal (Forestry Journal) ◽

10.37482/0536-1036-2020-6-9-21 ◽

2020 ◽

pp. 9-21

Author(s):

L.V. Vetchinnikova ◽

◽

A.F. Titov ◽

◽

Keyword(s):

Population Size ◽

Natural Populations ◽

Forest Tree ◽

Published Data ◽

Population Approach ◽

Key Factors ◽

History Of ◽

Individual Trees ◽

Karelian Birch

The article reports on the application of the best known principles for mapping natural populations of curly (Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti – one of the most appealing representatives of the forest tree flora. Relying on the synthesis and analysis of the published data amassed over nearly 100 years and the data from own full-scale studies done in the past few decades almost throughout the area where curly birch has grown naturally, it is concluded that its range outlined in the middle of the 20th century and since then hardly revised is outdated. The key factors and reasons necessitating its revision are specified. Herewith it is suggested that the range is delineated using the population approach, and the key element will be the critical population size below which the population is no longer viable in the long term. This approach implies that the boundaries of the taxon range depend on the boundaries of local populations (rather than the locations of individual trees or small clumps of trees), the size of which should not be lower than the critical value, which is supposed to be around 100–500 trees for curly birch. A schematic map of the curly birch range delineated using this approach is provided. We specially address the problem of determining the minimum population size to secure genetic diversity maintenance. The advantages of the population approach to delineating the distribution range of curly birch with regard to its biological features are highlighted. The authors argue that it enables a more accurate delineation of the range; shows the natural evolutionary history of the taxon (although it is not yet officially recognized as a species) and its range; can be relatively easily updated (e.g. depending on the scope of reintroduction); should be taken into account when working on the strategy of conservation and other actions designed to maintain and regenerate this unique representative of the forest tree flora.

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A Novel Vegetation Point Cloud Density Tree-Segmentation Model for Overlapping Crowns Using UAV LiDAR

Remote Sensing ◽

10.3390/rs13081442 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1442

Author(s):

Kaisen Ma ◽

Yujiu Xiong ◽

Fugen Jiang ◽

Song Chen ◽

Hua Sun

Keyword(s):

Point Cloud ◽

Local Maximum ◽

Window Size ◽

Point Clouds ◽

High Density ◽

Watershed Algorithm ◽

Canopy Area ◽

Individual Trees ◽

Optimal Window ◽

Cloud Density

Detecting and segmenting individual trees in forest ecosystems with high-density and overlapping crowns often results in bias due to the limitations of the commonly used canopy height model (CHM). To address such limitations, this paper proposes a new method to segment individual trees and extract tree structural parameters. The method involves the following key steps: (1) unmanned aerial vehicle (UAV)-scanned, high-density laser point clouds were classified, and a vegetation point cloud density model (VPCDM) was established by analyzing the spatial density distribution of the classified vegetation point cloud in the plane projection; and (2) a local maximum algorithm with an optimal window size was used to detect tree seed points and to extract tree heights, and an improved watershed algorithm was used to extract the tree crowns. The proposed method was tested at three sites with different canopy coverage rates in a pine-dominated forest in northern China. The results showed that (1) the kappa coefficient between the proposed VPCDM and the commonly used CHM was 0.79, indicating that performance of the VPCDM is comparable to that of the CHM; (2) the local maximum algorithm with the optimal window size could be used to segment individual trees and obtain optimal single-tree segmentation accuracy and detection rate results; and (3) compared with the original watershed algorithm, the improved watershed algorithm significantly increased the accuracy of canopy area extraction. In conclusion, the proposed VPCDM may provide an innovative data segmentation model for light detection and ranging (LiDAR)-based high-density point clouds and enhance the accuracy of parameter extraction.

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Using Discrete-Point LiDAR to Classify Tree Species in the Riparian Pacific Northwest, USA

Remote Sensing ◽

10.3390/rs13142647 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2647

Author(s):

Julia Tatum ◽

David Wallin

Keyword(s):

Pacific Northwest ◽

Tree Species ◽

3D Structure ◽

Alnus Rubra ◽

Populus Balsamifera ◽

Segmentation Method ◽

Black Cottonwood ◽

Riparian Landscape ◽

Individual Trees ◽

Species Mapping

Practical methods for tree species identification are important for both land management and scientific inquiry. LiDAR has been widely used for species mapping due to its ability to characterize 3D structure, but in structurally complex Pacific Northwest forests, additional research is needed. To address this need and to determine the feasibility of species modeling in such forests, we compared six approaches using five algorithms available in R’s lidR package and Trimble’s eCognition software to determine which approach most consistently identified individual trees across a heterogenous riparian landscape. We then classified segments into Douglas fir (Pseudotsuga menziesii), black cottonwood (Populus balsamifera ssp. trichocarpa), and red alder (Alnus rubra). Classification accuracies based on the best-performing segmentation method were 91%, 92%, and 84%, respectively. To our knowledge, this is the first study to investigate tree species modeling from LiDAR in a natural Pacific Northwest forest, and the first to model Pacific Northwest species at the landscape scale. Our results suggest that LiDAR alone may provide enough information on tree species to be useful to land managers in limited applications, even under structurally challenging conditions. With slight changes to the modeling approach, even higher accuracies may be possible.

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Bottom-up delineation of individual trees from full-waveform airborne laser scans in a structurally complex eucalypt forest

Remote Sensing of Environment ◽

10.1016/j.rse.2015.11.008 ◽

2016 ◽

Vol 173 ◽

pp. 69-83 ◽

Cited By ~ 25

Author(s):

Iurii Shendryk ◽

Mark Broich ◽

Mirela G. Tulbure ◽

Sergey V. Alexandrov

Keyword(s):

Bottom Up ◽

Eucalypt Forest ◽

Full Waveform ◽

Airborne Laser ◽

Individual Trees

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Characterisation of 14 microsatellite markers for the Australian fig psylloid, Mycopsylla fici

Australian Journal of Zoology ◽

10.1071/zo15027 ◽

2015 ◽

Vol 63 (4) ◽

pp. 233 ◽

Cited By ~ 2

Author(s):

Caroline Fromont ◽

Markus Riegler ◽

James M. Cook

Keyword(s):

Illumina Miseq ◽

Insect Herbivore ◽

Vertebrate Species ◽

Moreton Bay ◽

Lord Howe Island ◽

Hardy Weinberg Equilibrium ◽

Sap Feeding ◽

Polymorphic Microsatellite ◽

Individual Trees ◽

Two Populations

The Australian fig psylloid, Mycopsylla fici, is a sap-feeding insect herbivore that is host-specific to the Moreton Bay fig, Ficus macrophylla. It has periodic major outbreaks that can cause complete defoliation of individual trees and massive decrease in local leaf and fruit availability, with significant effects for many insect and vertebrate species that utilise the tree’s resources. We used ⅛ of an Illumina MiSeq run to sequence genomic DNA from two pools of five psylloids from two different field sites. We identified 14 polymorphic microsatellite loci and characterised them in 43 individuals from two populations (Sydney and Lord Howe Island, Australia). Within populations, the number of alleles ranged from 4 to 15 per locus with observed heterozygosity of 0–0.9. Four loci deviated from Hardy–Weinberg equilibrium. The microsatellite primers will be useful for the study of population genetics and gene flow within and between psylloid populations.

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The Climatology of Significant Tornadoes in the Czech Republic

Atmosphere ◽

10.3390/atmos11070689 ◽

2020 ◽

Vol 11 (7) ◽

pp. 689

Author(s):

Rudolf Brázdil ◽

Kateřina Chromá ◽

Tomáš Púčik ◽

Zbyněk Černoch ◽

Petr Dobrovolný ◽

...

Keyword(s):

Czech Republic ◽

Daily Variation ◽

Convective Available Potential Energy ◽

Vertical Wind Shear ◽

Severe Damage ◽

The Czech Republic ◽

Annual Variations ◽

Wide Range ◽

Individual Trees ◽

Common Era

In the Czech Republic, tornadoes may reach an intensity of F2 and F3 on the Fujita scale, causing “considerable” to “severe” damage. Documentary evidence is sufficient to allow the creation of a chronology of such events, from the earliest recorded occurrence in 1119 CE (Common Era) to 2019, including a total of 108 proven or probable significant tornadoes on 90 separate days. Since only 11 significant tornadoes were documented before 1800, this basic analysis centers around the 1811–2019 period, during which 97 tornadoes were recorded. Their frequency of occurrence was at its highest in the 1921–1930, 1931–1940, and 2001–2010 decades. In terms of annual variations, they took place most frequently in July, June, and August (in order of frequency), while daily variation favored the afternoon and early evening hours. Conservative estimates of human casualties mention 8 fatalities and over 95 people injured. The most frequent types of damage were related to buildings, individual trees, and forests. Tornadoes of F2–F3 intensity were particularly associated with synoptic types characterized by airflow from the western quadrant together with troughs of low pressure extending or advancing over central Europe. Based on parameters calculated from the ERA-5 re-analysis for the period of 1979–2018, most of these tornadoes occurred over a wide range of Convective Available Potential Energy (CAPE) values and moderate-to-strong vertical wind shear. The discussion herein also addresses uncertainties in tornado selection from documentary data, the broader context of Czech significant tornadoes, and the environmental conditions surrounding their origins.

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Adjudicating Perspectives on Forest Structure: How Do Airborne, Terrestrial, and Mobile Lidar-Derived Estimates Compare?

Remote Sensing ◽

10.3390/rs13122297 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2297

Author(s):

Jonathon J. Donager ◽

Andrew J. Sánchez Meador ◽

Ryan C. Blackburn

Keyword(s):

Ponderosa Pine ◽

Laser Scanning ◽

Canopy Cover ◽

Basal Area ◽

Tree Height ◽

Absolute Error ◽

Forest Monitoring ◽

Individual Tree ◽

Structural Configurations ◽

Individual Trees

Applications of lidar in ecosystem conservation and management continue to expand as technology has rapidly evolved. An accounting of relative accuracy and errors among lidar platforms within a range of forest types and structural configurations was needed. Within a ponderosa pine forest in northern Arizona, we compare vegetation attributes at the tree-, plot-, and stand-scales derived from three lidar platforms: fixed-wing airborne (ALS), fixed-location terrestrial (TLS), and hand-held mobile laser scanning (MLS). We present a methodology to segment individual trees from TLS and MLS datasets, incorporating eigen-value and density metrics to locate trees, then assigning point returns to trees using a graph-theory shortest-path approach. Overall, we found MLS consistently provided more accurate structural metrics at the tree- (e.g., mean absolute error for DBH in cm was 4.8, 5.0, and 9.1 for MLS, TLS and ALS, respectively) and plot-scale (e.g., R2 for field observed and lidar-derived basal area, m2 ha−1, was 0.986, 0.974, and 0.851 for MLS, TLS, and ALS, respectively) as compared to ALS and TLS. While TLS data produced estimates similar to MLS, attributes derived from TLS often underpredicted structural values due to occlusion. Additionally, ALS data provided accurate estimates of tree height for larger trees, yet consistently missed and underpredicted small trees (≤35 cm). MLS produced accurate estimates of canopy cover and landscape metrics up to 50 m from plot center. TLS tended to underpredict both canopy cover and patch metrics with constant bias due to occlusion. Taking full advantage of minimal occlusion effects, MLS data consistently provided the best individual tree and plot-based metrics, with ALS providing the best estimates for volume, biomass, and canopy cover. Overall, we found MLS data logistically simple, quickly acquirable, and accurate for small area inventories, assessments, and monitoring activities. We suggest further work exploring the active use of MLS for forest monitoring and inventory.

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