Top Of Tree Research Articles

Wind and gravity in shaping Picea trunks

Key messageSpruce trunk tapering corresponds closely to tapering required to resist bending forces caused by wind and gravity.Understanding why trunks (tree stems) are the size that they are is important. However, this understanding is fragmented into isolated schools of thought and has been far from complete. Realistic calculations on minimum trunk diameters needed to resist bending moments caused by wind and gravity would be a significant step forward. However, advancements using this biomechanical approach have been delayed by difficulties in modelling bending of trunks and wind gusts. We felled and measured five Norway spruces (Picea abies) in an unthinned monoculture in southeastern Finland planted 67 years earlier. We then focused on forces working on storm-bent (maximally bent) trees caused by gravity and the strongest gust in a 1-h simulation with a large-eddy simulation model. The weakest points along the trunks of the three largest trees resisted mean above-canopy wind speeds ranging from 10.2 to 12.7 m s−1 (3.3-fold in the strongest gust), but the two smallest were well protected by a dense layer of leaves from the bending tops of larger trees, and could have resisted stronger winds. Gravity caused approximately one quarter of the critical bending moments. The wind that breaks the trunks in their weakest points is close to breaking them in other points, supporting the importance of bending moments caused by wind and gravity in the evolution of trunk taper.

Efficient individual tree identification from multiple source point cloud

Detection and identification of individual trees are becoming increasingly important for forest related applications. Current, researches mostly concentrate on the segmentation of canopy height models (CHMs), which only produce rough tree delineation and numbers. Considering that different trees have changeable economic value and growing speed, this approach proposed a robust workflow that detects not only the location and shape of single trees but also the basic tree type. First, the multiple source point clouds are combined and classified to build the CHMs, based on the geometric information. Then, the tree tops are extracted based on the mathematical morphology operations. The tree delineation are then grown based on the tree tops and the competition among adjacent tress is considered. Finally, a multi-view projection based classification network was developed to identify the tree type, which meanwhile indicate the connecting trees that are hardly separated in CHMs. Experiments results on various data source demonstrate that the proposed approach can produce significant improvements on the detection results than existing researches.

Ornithology from the Tree Tops

Ornithology from the Tree Tops

Oblique view individual tree crown delineation

Individual tree crown (ITC) segmentation supports numerous applications in forest management and ecology. In the latter context, special attention is dedicated to the study of angular reflection effects, caused by the interaction of incident sunlight with a canopy. High precision airborne analysis of these effects requires multi-view sensor systems and multi-view ITC segmentation. In particular oblique view image segmentation is difficult and has been addressed by numerous template based methods. This contribution identifies persistent shortcomings in the state of the art and tackles the problem by a multi-step workflow utilizing the digital surface model (DSM), derived from multi-view stereo data. A slightly revised version of the previously published levelset-watershed segmentation of the DSM is presented as the first step. In the second step, the contour of the visible part of a candidate tree in images with known orientation is obtained by means of ray casting and concave hull calculation. The method was tested on a deciduous, mixed and coniferous plot, whose aerial images were acquired using the 3K camera system in 2018 at Kranzberg Forest, Bavaria, Germany. Accuracies were assessed at hand of human operator generated groundtruth tree tops for the DSM as well as images with zenit angles of approximately 0,45 and 52 degrees. The resulting F1-scores, averaged over the plots, are 0.909/0.902/0.886/0.876 for the DSM/near-nadir-/oblique-/maximum-oblique-images, respectively.

Mapping individual silver fir trees using hyperspectral and LiDAR data in a Central European mixed forest

Mapping a specific tree species at individual tree level across landscapes using remote sensing is challenging, especially in forests where co-occurring tree species exhibit similar characteristics. In Central European mixed forests, silver fir and Norway spruce have been identified as a pair of coniferous tree species with similar spectral and structural characteristics, typically leading to a major misclassification error in mapping studies. Here, we aimed to accurately map individual silver fir trees in a spruce-dominated natural forest in the Bavarian Forest National Park using integrated airborne hyperspectral and LiDAR data. To accomplish this goal, we extracted a set of relevant spectral and structural features from the hyperspectral and LiDAR data and used them to build machine learning classification models. Specifically, we compared the performance of three one-class classification algorithms (i.e. one-class support vector machine, biased support vector machine, and maximum entropy) for mapping individual silver fir trees. Our results showed that the biased support vector machine classifier yielded the highest mapping accuracy, with the area under the curve for positive and unlabeled samples (puAUC) achieving 0.95 (kappa 0.90). We found that the intensity value of 95th percentile of normalized tree height and the percentage of first returns above 2 m high were the most influential structural features, capturing the main morphological difference between silver fir and Norway spruce at the top tree crown. We also found that the wavebands at 700.1 nm, 714.5 nm, and 1201.6 nm were the most robust spectral bands, which are strongly affected by chlorophyll and foliar water content. Our study suggests that discovering links between spectral and structural features captured by different remotely sensed data and species-specific traits can significantly improve the mapping accuracy of a focal species at the individual tree level.

Canopy Top, Height and Photosynthetic Pigment Estimation Using Parrot Sequoia Multispectral Imagery and the Unmanned Aerial Vehicle (UAV)

Remote sensing is one of the modern methods that have significantly developed over the last two decades and, nowadays, it provides a new means for forest monitoring. High spatial and temporal resolutions are demanded for the accurate and timely monitoring of forests. In this study, multi-spectral Unmanned Aerial Vehicle (UAV) images were used to estimate canopy parameters (definition of crown extent, top, and height, as well as photosynthetic pigment contents). The UAV images in Green, Red, Red-Edge, and Near infrared (NIR) bands were acquired by Parrot Sequoia camera over selected sites in two small catchments (Czech Republic) covered dominantly by Norway spruce monocultures. Individual tree extents, together with tree tops and heights, were derived from the Canopy Height Model (CHM). In addition, the following were tested: (i) to what extent can the linear relationship be established between selected vegetation indexes (Normalized Difference Vegetation Index (NDVI) and NDVIred edge) derived for individual trees and the corresponding ground truth (e.g., biochemically assessed needle photosynthetic pigment contents) and (ii) whether needle age selection as a ground truth and crown light conditions affect the validity of linear models. The results of the conducted statistical analysis show that the two vegetation indexes (NDVI and NDVIred edge) tested here have the potential to assess photosynthetic pigments in Norway spruce forests at a semi-quantitative level; however, the needle-age selection as a ground truth was revealed to be a very important factor. The only usable results were obtained for linear models when using the second year needle pigment contents as a ground truth. On the other hand, the illumination conditions of the crown proved to have very little effect on the model’s validity. No study was found to directly compare these results conducted on coniferous forest stands. This shows that there is a further need for studies dealing with a quantitative estimation of the biochemical variables of nature coniferous forests when employing spectral data that were acquired by the UAV platform at a very high spatial resolution.

Voxel-Based Automatic Tree Detection and Parameter Retrieval from Terrestrial Laser Scans for Plot-Wise Forest Inventory

This paper presents a fully automatic method addressing tree mapping and parameter extraction (tree position, stem diameter at breast height, stem curve, and tree height) from terrestrial laser scans in forest inventories. The algorithm is designed to detect trees of various sizes and architectures, produce smooth yet accurate stem curves, and achieve tree height estimates in multi-layered stands, all without employing constraints on the shape of the crown. The algorithm also aims to balance estimation accuracy and computational complexity. The method’s tree detection combines voxel operations and stem surface filtering based on scanning point density. Stem diameters are obtained by creating individual taper models, while tree heights are estimated from the segmentation of tree crowns in the voxel-space. Twenty-four sample plots representing diverse forest structures in the south boreal region of Finland have been assessed from single- and multiple terrestrial laser scans. The mean percentages of completeness in stem detection over all stand complexity categories are 50.9% and 68.5% from single and multiple scans, respectively, while the mean root mean square error (RMSE) of the stem curve estimates ranges from ±1.7 to ±2.3 cm, all of which demonstrates the robustness of the algorithm. Efforts were made to accurately locate tree tops by segmenting individual crowns. Nevertheless, with a mean bias of −2.9 m from single scans and −1.3 m from multiple scans, the algorithm proved conservative in tree height estimates.

Development of Areca Nut Climbing And Harvesting Machine With Pesticide

Recent days there were lots of improvement and advancement have been done in the field of agriculture, but the sad thing is the large scale farmers always earns more than the small scale farmers when comparing its ratio. The project focuses on the growth of small scale farmers as equal to the growth of the large scale farmers in the field of agriculture in growing the palm trees. The palm trees usually grow in narrow dimensions and the time taken to harvest the crop nuts will be around 3 to 4 years. Total investment is based on the harvesting and the cost and machines to harvest the crop nuts were of huge amount and the small scale farmers struggle a lot and that leads to loss. Also there is a chance of losing the quantity of crop nuts when harvested from the top of the palm tree when all the nuts will be scattered and is wasted falls down on the ground. Therefore we thought of designing a product that can be operated by the by the farmer itself a user friendly and easy to handle, also we have focused on safe landing of the crop nuts from the top of the palm tree. This product completely works based on the mechanical concepts and designed with mechanical links. It is operated manually now; in the future it will be automated. This product will decrease the cost of harvesting and increase the profit for the small scale farmers to grow their ration as that of the large scale farmers. This will create a revolution in the field of crop harvesting which benefits lots of farmers to come up from their bad time to good time.

Forest Height Estimation Using a Single-Pass Airborne L-Band Polarimetric and Interferometric SAR System and Tomographic Techniques

This paper addresses forest height estimation for boreal forests at the test site of Edson in Alberta, Canada, using dual-baseline PolInSAR dataset measured by Intermap’s single-pass system. This particular dataset is acquired by using both ping-pong and non-ping-pong modes, which permit forming a dual-baseline TomoSAR configuration, i.e., an extreme configuration for tomographic processing. A tomographic approach, based on polarimetric Capon and MUSIC estimators, is proposed to estimate the elevation of tree top and of underlying ground, and hence forest height is estimated. The resulting forest DTM and DSM over the test site are validated against LiDAR-derived estimates, demonstrating the undeniable capability of the single-pass L-band PolInSAR system for forest monitoring.

Modeling of the process of collection, sorting and transportation of logging residues at the logging area

Effectiveness of economic development of logging industry is impossible without scientifically grounded strategies of formation of perspective technological logging processes with complex use of the total biomass of harvested trees. Degree of utilization of wood biomass is to be considered the most important principle of progressive logging technology. One of the main tasks of the national logging complex is the use of low-grade wood, lumpy wood waste, top of trees, twigs and branches, which will significantly improve efficiency of logging. To solve this problem, this article reviews the process of modeling of work of sorting and transportation machine designed for loading, sorting and transportation of felling residues to timber road. The technological scheme also provides cutting waste with knife for sorting by size. The study provides a detailed technological scheme of logging operations using forwarders with a removable body for loading, sorting and transportation of felling residues. The body of the forwarder is divided into compartments for transportation of waste with different parameters. The information and logical model of the process of collection, sorting and transportation of felling residue, which is proposed by machine, was offered. The formula for calculating the performance of operation of the sorting and transportation machine was obtained. Sorting according to species and types of felling residues is necessary for the production of fuel and technological wood chips for further use in production of valuable commercial products.

ЭВОЛЮЦИЯ ОБРАЗА НЕБА («ТЭНГЭР») В ДАУРСКОЙ КУЛЬТУРЕ

The article studies the historical transformation of the image of the sky in Daurian culture. The authors analyze the myths and shamanistic rituals of the Daur people. The concept of the sky - “tenger” - refers not only to the sky itself, but also to the tops of deer horns, tree tops, the upper part of human and horse’s heads. The authors compare the Daurian and Buryat shamanistic rituals and reveal many similar points. They come to the conclusion that the ancient people worshiped the image of “tenger” as the sun and the moon. After the Neolithic period, “tenger” worship was expressed in the totemistic cult of eagle. The cult of horse was also associated with the sky worship; Daurs sacrificed white horses and bulls to the sky. The authors find out the solar origin of the fairytale heroes of some Daurian myths as well. The sun also appeared as mother in mythical representation. Ancient people considered the sun and the moon as a man and a woman respectively. In the period of matriarchy, when paired marriages arose, there appeared the Daurian myth of marriage of two siblings to two celestial fairies (dakini)...

The Eucalyptus Grove (an excerpt)

FICTION The Eucalyptus Grove (an excerpt) by Ruby Namdar I’ve seen it more than once: the raised axe swings and chops into the last remnant; Lying still in the dirt is the moving, glowing crown. – Rahel, Eucalyptus T he gray-green tops of the eucalyptus trees were the first thing Avi saw every year as the sluggish Fishermen’s Island ferry slowed down at the entrance to the port. Searching for the treetops, his eyes flitted over the green horizon, spotted gray by the rooftops of the sprawling vacation homes, and didn’t come to rest until finding them, as strange and familiar as always. Seemingly, the eucalyptus trees didn’t belong on the island: they were unusually tall and towered over the local brush; their leaves had a faded, arid look; the gray dirt of the grove was also different from the island’s dark, fertile soil. And yet, though the trees were utterly alien to the landscape and climate of Fishermen’s Island, nothing symbolized his bond to the place better, a bond that began over thirty years earlier when he and his first wife, Odelia, bought a house on the island and started spending their summers there. But something was different about the view this year, and Avi’s visual search went awry. His gaze sped back and forth over the horizon, going faster and faster, searching in vain for the silvery-greenish stain of the grove. They weren’t there, they were gone. His eucalyptus trees had disappeared as if they had been swallowed by the earth, as if they had never been there. Avi WORLDLIT.ORG 71 PHOTO BY MYRTLE SCHILLING ON UNSPLASH was gripped by an eerie, intense unease. The sudden disappearance of the trees disrupted the festive sense of anticipation that filled him every year when the ferry drew close to Fishermen’s Island, separating him from his daily worries and routine concerns and carrying him to this calm, wonderful place for which he had such intimate feelings, even though it was so different from the landscapes of his distant childhood. His large hands gripped the damp rail tightly. He leaned over and continued to scan the horizon as if believing he could will the lost trees back into existence. The ferry blew its loud, metallic foghorn, alerting the crew at the pier of its imminent arrival. He had to go find Lauren and the kid, who were probably still amusing themselves by throwing bits of bread to the seagulls that hovered over the ferry, hoping for scraps, and take them to the car down in the hold. Avi detached himself from the handrail, gazed for the last time at where the eucalyptus trees were supposed to be, and went to look for his young wife and their three-year-old, Alex. The short drive to the house was spent in unpleasant silence. He was distracted. He forgot to slow down before stop signs and had to make abrupt stops that made the car shudder, the bottles of wine in the back clink in protest, and Lauren to flare up in annoyance. Upon the long-awaited arrival at the house, the usual festive feeling was still absent. Avi clambered out of the car, stretched his legs, and looked around, but he wasn’t suffused with strange joy as he usually was; he didn’t take in the salty sea air with relish; he didn’t ramble busily between the rooms of the house, checking the taps and fixtures to make sure they were working properly; he didn’t even unload the wine from the trunk of the car, a crateful that he had selected with great care and pleasure at his wine shop in Princeton, a cherished annual rite forced upon him by the puritanical laws preserved since Prohibition in many counties and towns in the state of Massachusetts, including wide swaths of Fishermen’s Island where the sale of alcoholic beverages was completely banned. He helped the still-scowling Lauren with the suitcases, muttered a confused excuse that even he didn’t comprehend, got back in the car, and drove in the direction of the main road, not knowing where he...

Poetics of short story title

The article is about title of a literary work.It involves peculiar and distictive aspects of title stylistics in Uzbek short stories and studies its edges, which reveal literary notion of the authior. However, we can see the opposite of this statement in short stories with sarcastic title. For example, one may not perceive the reason for naming short story “The thief” until reading the literary work itself, consequently, we are not able to understand the inner meaning of it. “Strong fall wind, that is not letting to open the eyes for about two weeks is whistling over the top of lonely trees, it is buzzing; hustling over the veins, going straight forward windows and doors and sighing”.

The Eucalyptus Grove <em>(an excerpt)</em>

FICTION The Eucalyptus Grove (an excerpt) by Ruby Namdar I’ve seen it more than once: the raised axe swings and chops into the last remnant; Lying still in the dirt is the moving, glowing crown. – Rahel, Eucalyptus T he gray-green tops of the eucalyptus trees were the first thing Avi saw every year as the sluggish Fishermen’s Island ferry slowed down at the entrance to the port. Searching for the treetops, his eyes flitted over the green horizon, spotted gray by the rooftops of the sprawling vacation homes, and didn’t come to rest until finding them, as strange and familiar as always. Seemingly, the eucalyptus trees didn’t belong on the island: they were unusually tall and towered over the local brush; their leaves had a faded, arid look; the gray dirt of the grove was also different from the island’s dark, fertile soil. And yet, though the trees were utterly alien to the landscape and climate of Fishermen’s Island, nothing symbolized his bond to the place better, a bond that began over thirty years earlier when he and his first wife, Odelia, bought a house on the island and started spending their summers there. But something was different about the view this year, and Avi’s visual search went awry. His gaze sped back and forth over the horizon, going faster and faster, searching in vain for the silvery-greenish stain of the grove. They weren’t there, they were gone. His eucalyptus trees had disappeared as if they had been swallowed by the earth, as if they had never been there. Avi WORLDLIT.ORG 71 PHOTO BY MYRTLE SCHILLING ON UNSPLASH was gripped by an eerie, intense unease. The sudden disappearance of the trees disrupted the festive sense of anticipation that filled him every year when the ferry drew close to Fishermen’s Island, separating him from his daily worries and routine concerns and carrying him to this calm, wonderful place for which he had such intimate feelings, even though it was so different from the landscapes of his distant childhood. His large hands gripped the damp rail tightly. He leaned over and continued to scan the horizon as if believing he could will the lost trees back into existence. The ferry blew its loud, metallic foghorn, alerting the crew at the pier of its imminent arrival. He had to go find Lauren and the kid, who were probably still amusing themselves by throwing bits of bread to the seagulls that hovered over the ferry, hoping for scraps, and take them to the car down in the hold. Avi detached himself from the handrail, gazed for the last time at where the eucalyptus trees were supposed to be, and went to look for his young wife and their three-year-old, Alex. The short drive to the house was spent in unpleasant silence. He was distracted. He forgot to slow down before stop signs and had to make abrupt stops that made the car shudder, the bottles of wine in the back clink in protest, and Lauren to flare up in annoyance. Upon the long-awaited arrival at the house, the usual festive feeling was still absent. Avi clambered out of the car, stretched his legs, and looked around, but he wasn’t suffused with strange joy as he usually was; he didn’t take in the salty sea air with relish; he didn’t ramble busily between the rooms of the house, checking the taps and fixtures to make sure they were working properly; he didn’t even unload the wine from the trunk of the car, a crateful that he had selected with great care and pleasure at his wine shop in Princeton, a cherished annual rite forced upon him by the puritanical laws preserved since Prohibition in many counties and towns in the state of Massachusetts, including wide swaths of Fishermen’s Island where the sale of alcoholic beverages was completely banned. He helped the still-scowling Lauren with the suitcases, muttered a confused excuse that even he didn’t comprehend, got back in the car, and drove in the direction of the main road, not knowing where he...

Tracking of any intruder on territory border using 360-degree radar and sensor

In the era of modern world, lot of human lives are engaged with this perilous procedure of observation. Reconnaissance is a perilous activity. There is consistently a danger of getting trapped in spying, so we plan to discover safety with no risk. Doppler radar used for producing true results considering all army activity involved with data during transmission. This project presents an approach in detecting an intruder in a border using Doppler radar-based Intrusion Detection Systems which can be mounted on watch towers, grill fences, top of trees etc., Experimental results show that the use of the display as classifiers are more efficient in malicious intruder accurately. The data collected from the sensor and transmit through the Lora WAN to the hub. The performance of the Intrusion Detection System (IDS) is evaluated in comparison to other classifiers, displaying the testing accuracy, sensitivity, specificity, and precision. Doppler based Intrusion Detection Systems have shown increased efficiency and low false positives. It has the advantages of working in all weather conditions such as heavy sunshine, heavy rainfall with proper data.

Biotic and abiotic effects on density, body size, sex ratio, and survival in immature stages of the European woodwasp, Sirex noctilio.

Resource quality can have direct or indirect effects on female oviposition choice, offspring growth and survival, and ultimately on body size and sex ratio. We examined these patterns in Sirex noctilio Fabricus, the globally invasive European pine woodwasp, in South African Pinus patula plantations. We studied how tree position as well as natural variation in biotic and abiotic factors influenced sex‐specific density, larval size, tunnel length, male proportion, and survival across development. Twenty infested trees divided into top, middle, and bottom sections were sampled at three time points during larval development. We measured moisture content, bluestain fungal colonization, and co‐occurring insect density and counted, measured, and sexed all immature wasps. A subset of larval tunnels was measured to assess tunnel length and resource use efficiency (tunnel length as a function of immature wasp size). Wasp density increased from the bottoms to the tops of trees for both males and females. However, the largest individuals and the longest tunnels were found in bottom sections. Male bias was strong (~10:1) and likewise differed among sections, with the highest proportion in the middle and top sections. Sex ratios became more strongly male biased due to high female mortality, especially in top and middle sections. Biotic and abiotic factors such as colonization by Diplodia sapinea, weevil (Pissodes sp.) density, and wood moisture explained modest residual variation in our primary mixed effects models (0%–22%). These findings contribute to a more comprehensive understanding of sex‐specific resource quality for S. noctilio and of how variation in key biotic and abiotic factors can influence body size, sex ratio, and survival in this economically important woodwasp.

Return of the Dragon

In 2019, China was just about maintaining its position at the top of the EV tree. By mid 2020 - amid all of the pandemic-related issues - other regions had stepped up and closed the gap. Despite global market uncertainty, China is on a recharge for 2021

The use of soil nutrient balances in deriving forest biomass harvesting guidelines specific to region, tree species and soil type in the Netherlands

The substitution of biomass for fossil fuels in energy consumption is a measure to decrease the emissions of greenhouse gases and thereby mitigate global warming. During recent years, this has led to an increasing interest to use tree harvest residues as feedstock for bioenergy. An important concern related to the removal of harvesting residues is, however, the potential adverse effects on soil fertility caused by increased nutrient removal, relative to conventional stem-only harvesting. In the Netherlands this is a major concern, since most forests are located on poor sandy soils.To develop forest harvesting guidelines, we applied a mass balance approach comparing nutrient inputs by deposition and weathering with nutrient outputs by harvesting and leaching for various timber harvesting scenarios, including both stem-only harvesting and additional removal of tree tops and branches. A distinction was made in seven major tree species, six soil types (three sandy soils, loam, clay and peat soils) and nine regions, with clear variations in atmospheric deposition of phosphorus (P), calcium (Ca), magnesium (Mg) and potassium (K). For each region-tree-soil combination we calculated the maximum amounts that can be harvested such that the output of the nutrients Ca, Mg, K and P is balanced with the inputs. Results showed that at current harvesting rates, a negative balance of Ca, Mg, K or P is hardly calculated for the richer loamy to clayey soil types, while depletion can occur for the poorer sandy soils, particularly of P and K. Results are used to derive forest biomass harvesting guidelines, taking the uncertainties in the mass balance approach into account. The role of mitigating management approaches is also discussed.

Основные размерно-качественные характеристики круглых лесоматериалов, заготавливаемых в Архангельской области

The efficiency of woodworking enterprises largely depends on the size and qualitative characteristics of round timber. The paper aims to assess the main inventory characteristics of round timber in economically accessible forest areas of Arkhangelsk region. The studies were carried out at a number of large enterprises in Arkhangelsk region using a modern VECTOR 3D photometric scanner. Measurements were made on the line for sorting logs by diameter at the warehouses of raw materials. There were examined 18,931 sawlogs. The length of each log was 6 m. The diameter range of round timber was from 10 to 42 cm. As a result of experiments, the average diameter of harvested logs of pine and spruce were found and the parameters of curvature, taper and bark content were determined depending on the top diameter of round timber. The region continues to trend a gradual decrease in the average diameter of round timber, the value of which in the considered period 2014–2018 varied in the range of 11–16 cm. Simultaneously with a decrease in the average diameter of round timber, the curvature, taper and bark content are reduced, which may indirectly indicate that wood under the age of ripeness is involved in industrial production. If in the 2000s small and medium-sized timber was harvested mainly from the tree top, today, it can be assumed that the source of such timber is young trees that have not reached the age of industrial ripeness but grow near the road infrastructure. Changes in the dimensional and qualitative characteristics of round timber are of a system nature and are makings for the modernization of the machinery and equipment used by logging enterprises and sawmills. In the context of reducing the average diameter of round timber, in order to maintain current performance and volume output of sawn timber, it is necessary to increase feed rates and introduce an optimization system resulting in provision of individual cutting of logs in accordance with their size and shape.For citation: Tambi A.A., Ugryumov S.A., Birman A.R., Chernogradskaya I.A. Dimensional and Qualitative Characteristics of Round Timber Harvested in Arkhangelsk Region. Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 4, pp. 147–156. DOI: 10.37482/0536-1036-2020-4-147-156

Robustness of Parametric and Nonparametric Fitting Procedures of Tree-Stem Taper with Alternative Definitions for Validation Data

AbstractThis study aims to evaluate the robustness of parametric and nonparametric procedures using alternative definitions of validation data for loblolly pine. Specifically, four data division strategies were implemented: random selection of one-third of the trees in the data set, selection of the smallest one-third of the trees by diameter at breast height (DBH), selection of the middle third of the trees by DBH, and selection of the largest third of the trees by DBH. Results indicate that tree taper was predicted reasonably well by both procedures when the smallest, medium-sized, or randomly selected trees were withheld for validation. However, when the largest trees were withheld for validation, diameters predicted by the nonparametric random forest algorithm were considerably less accurate than those predicted by the parametric models, especially for diameters near the tree top. When extrapolation is anticipated, a carefully designed data-partitioning strategy should provide some protection against poor results for given prediction objectives.Study ImplicationsParametric tree-stem taper models have been widely applied in forestry. Recently, nonparametric methods with computationally intensive algorithms were proposed for estimating tree taper, but reliability of the methods has not been explicitly examined. In practice, models are commonly applied to predict unknown populations, which may vary from the observations used in model development. This study provides insights for natural resource and forest managers to select appropriate validation procedures when developing models for predicting tree-stem taper and examining robustness of parametric and nonparametric fitting of tree-stem taper under varying levels of interpolation/extrapolation from fitting to validation of data.