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Keywords = number of trees per hectare

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16 pages, 1726 KiB  
Article
Analysis of Operational Performance and Costs of Log Loaders Under Different Conditions
by Cássio Furtado Lima, Leonardo França da Silva, Cristiano Márcio Alves de Souza, Francisco de Assis Costa Ferreira, Luciano José Minette, Fernando Mateus Paniagua Mendieta, Roldão Carlos Andrade Lima, Luís Carlos de Freitas, Jéssica Karina Mesquita Vieira, Victor Crespo de Oliveira, Bruno Leão Said Schettini and Arthur Araújo Silva
Forests 2025, 16(6), 913; https://doi.org/10.3390/f16060913 - 29 May 2025
Viewed by 573
Abstract
The Brazilian forestry sector comprises 9.94 million hectares of plantations, with eucalyptus dominating 75% of this area for pulp production. Technological advances have enhanced machinery performance, with the cut-to-length system being the primary method for pulpwood production. This study aimed to optimize the [...] Read more.
The Brazilian forestry sector comprises 9.94 million hectares of plantations, with eucalyptus dominating 75% of this area for pulp production. Technological advances have enhanced machinery performance, with the cut-to-length system being the primary method for pulpwood production. This study aimed to optimize the operational cycle of the log loader by evaluating productivity, operational cycles, and loading costs. Data were collected in Bahia, northeastern Brazil, from a forestry company operating under varying productivity scenarios and forest rotations. Time and motion studies were conducted to assess the log loader’s cycles, while productivity and cost analyses were performed. The results indicated that predictive models effectively explained productivity variations. The log loader’s productivity increased with the average volume per tree (AVT) and decreased with the number of movements, which consumed 68% of the cycle time due to wood adjustment and stack organization. Stages such as personal breaks, truck movements, crane adjustments, and cleaning of fallen material showed no significant statistical differences. Loading costs rose by up to 154% with increased movements and decreased with a higher AVT. Additionally, loading tri-train trucks significantly influenced transportation efficiency, emphasizing the importance of optimizing the log loader’s cycle to balance costs and enhance transportation operations. Full article
(This article belongs to the Section Forest Operations and Engineering)
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23 pages, 3686 KiB  
Article
A Whole-Stand Model for Estimating the Productivity of Uneven-Aged Temperate Pine-Oak Forests in Mexico
by María Guadalupe Nava-Miranda, Juan Gabriel Álvarez-González, José Javier Corral-Rivas, Daniel José Vega-Nieva, Jaime Briseño-Reyes, Jesús Aguirre-Gutiérrez and Klaus von Gadow
Sustainability 2025, 17(8), 3393; https://doi.org/10.3390/su17083393 - 10 Apr 2025
Viewed by 635
Abstract
This study presents a model for estimating forest productivity based on a sample of 2048 permanent field plots covering a wide range of growing sites in Mexico. Our state-space approach assumes that the growth behavior of any stand over time can be estimated [...] Read more.
This study presents a model for estimating forest productivity based on a sample of 2048 permanent field plots covering a wide range of growing sites in Mexico. Our state-space approach assumes that the growth behavior of any stand over time can be estimated on the basis of its current state, defined by the dominant height (H), number of trees per hectare (N), and stand basal area (BA). We used transition functions to estimate the change in states as a function of the current state. We also present transition functions for the change in stand volume (V) and total above-ground biomass (AGB). The first transition function relates dominant height to dominant diameter by using the guide-curve method to estimate site form. The transition function for N consists of two models, one for estimating natural mortality and the other for estimating recruitment. These models were developed in two steps: in the first step, the logistic regression and maximum likelihood approach were used to estimate the probability of the occurrence of mortality or recruitment, and in the second step, the rate of change associated with each event was modeled when mortality or recruitment was assumed to have occurred as a result of the first step. The remaining three transition functions (BA, V, and AGB) were fitted simultaneously to account for possible correlations between errors. The model estimating total above-ground biomass (AGB), which can be considered a state variable that summarizes the performance of the whole model, explained more than 97% of the observed variability, with a root mean square error value of 10.57 Mg/ha. Full article
(This article belongs to the Special Issue Sustainable Forestry Management and Technologies)
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13 pages, 1978 KiB  
Article
How to Define Spacing Among Forest Trees to Mitigate Competition: A Technical Note
by Khodabakhsh Zabihi, Vivek Vikram Singh, Aleksei Trubin, Nataliya Korolyova and Rastislav Jakuš
Biology 2025, 14(3), 296; https://doi.org/10.3390/biology14030296 - 15 Mar 2025
Cited by 1 | Viewed by 843
Abstract
Establishing an optimum range of inter-species spacing that reduces competition among trees and mitigates the effects of drought is a critical yet complex challenge in forest management. Stand density plays a crucial role in forest functioning by regulating resource allocation within individual trees. [...] Read more.
Establishing an optimum range of inter-species spacing that reduces competition among trees and mitigates the effects of drought is a critical yet complex challenge in forest management. Stand density plays a crucial role in forest functioning by regulating resource allocation within individual trees. Higher stand densities have been shown to reduce sap velocities, indicating intensified competition for water and other resources. However, determining the precise spacing that minimizes competition while maintaining ecosystem balance remains unclear. In this study, conducted in temperate Norway spruce forests at an altitude range of 400–500 m in the Czech Republic, we propose a novel technique to define tree spacing that reduces competitive interactions. We used xylem sap flow residuals of an ordinary least square (OLS) regression model to filter out the effects of elevation and diameter at breast height (DBH) on field-measured sap flow for 101 planted Norway spruce trees with a DBH range of 40 ± 5 cm (≈90–100 years old). The model residuals allowed us to account for the most important driver of sap flow variability: tree density and its underlying effects on individual tree traits. To minimize the confounding effects of temporal and spatial variability, we used twelve consecutive daily measurements of sap flow (6 a.m. to 6 p.m.) taken at the start of the growing season. By constructing an experimental variogram, we quantified sap flow variability as a function of tree spacing. The results showed a steady sap flow pattern at tree densities of 12, 11, and 10 trees per 314 m2 (equivalent to 350 ± 32 trees per hectare), corresponding to inter-tree spacing measurements of 5.12 m, 5.34 m, and 5.60 m, respectively. These findings suggest that when the N number of trees (median) per unit area (A) is in equilibrium with resource availability, increasing or decreasing the n number of trees may not significantly change competition levels (A; f(A) = N ± n). The size or deviation of n depends on the area to define the minimum and maximum thresholds or tolerance capacity for the number of trees allowed to be in the area. This technique—using a variogram of sap flow residuals to determine tree spacing—can be periodically applied, such as every 10–15 years, and adapted for different elevation gradients (e.g., within 100 m intervals). It offers a practical tool for forest managers and policymakers, guiding thinning and planting strategies to enhance forest resilience in the face of water-stress conditions. Full article
(This article belongs to the Special Issue Young Researchers in Plant Sciences)
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22 pages, 35296 KiB  
Article
Estimating Olive Tree Density in Delimited Areas Using Sentinel-2 Images
by Adolfo Lozano-Tello, Jorge Luceño, Andrés Caballero-Mancera and Pedro J. Clemente
Remote Sens. 2025, 17(3), 508; https://doi.org/10.3390/rs17030508 - 31 Jan 2025
Viewed by 980
Abstract
The objective of this study is to develop a method for estimating the density of olive trees in delimited plots using low-resolution images from the Sentinel-2 satellite. This approach is particularly relevant in certain regions where high-resolution orthophotos, which are often costly and [...] Read more.
The objective of this study is to develop a method for estimating the density of olive trees in delimited plots using low-resolution images from the Sentinel-2 satellite. This approach is particularly relevant in certain regions where high-resolution orthophotos, which are often costly and not always available, cannot be accessed. This study focuses on the Extremadura region in Spain, where 48,530 olive plots were analysed. Data from Sentinel-2’s multispectral bands were obtained for each plot, and a Random Forest Regression (RFR) model was used to correlate these values with the number of olive trees, previously counted from orthophotos using machine learning object detection techniques. The results show that the proposed method can predict olive tree density within an acceptable error margin, which is especially useful for distinguishing plots with a density greater than 300 olive trees per hectare—a key criterion for allocating agricultural subsidies in the region. Although the accuracy of the model is not optimal, an average error of ±15.04 olive trees per hectare makes it a viable tool for practical applications where extreme precision is not required. The developed method may also be extrapolated to other cases and crop types, such as fruit trees or forest masses, offering an efficient solution for annual density estimates without relying on costly aerial images. Future research could enhance the accuracy of the model by grouping plots according to additional characteristics, such as tree size or plantation type. Full article
(This article belongs to the Special Issue Recent Advances in Remote Sensing Image Processing Technology)
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25 pages, 22247 KiB  
Article
Small Gap Dynamics in High Mountain Central European Spruce Forests—The Role of Standing Dead Trees in Gap Formation
by Denisa Sedmáková, Peter Jaloviar, Oľga Mišíková, Ladislav Šumichrast, Barbora Slováčková, Stanislav Kucbel, Jaroslav Vencurik, Michal Bosela and Róbert Sedmák
Plants 2024, 13(24), 3502; https://doi.org/10.3390/plants13243502 - 15 Dec 2024
Viewed by 852
Abstract
Gap dynamics are driving many important processes in the development of temperate forest ecosystems. What remains largely unknown is how often the regeneration processes initialized by endogenous mortality of dominant and co-dominant canopy trees take place. We conducted a study in the high [...] Read more.
Gap dynamics are driving many important processes in the development of temperate forest ecosystems. What remains largely unknown is how often the regeneration processes initialized by endogenous mortality of dominant and co-dominant canopy trees take place. We conducted a study in the high mountain forests of the Central Western Carpathians, naturally dominated by the Norway spruce. Based on the repeated forest inventories in two localities, we quantified the structure and amount of deadwood, as well as the associated mortality of standing dead canopy trees. We determined the basic specific gravity of wood and anatomical changes in the initial phase of wood decomposition. The approach for estimating the rate of gap formation and the number of canopy trees per unit area needed for intentional gap formation was formulated based on residence time analysis of three localities. The initial phase of gap formation (standing dead tree in the first decay class) had a narrow range of residence values, with a 90–95% probability that gap age was less than 10 or 13 years. Correspondingly, a relatively constant absolute number of 12 and 13 canopy spruce trees per hectare died standing in 10 years, with a mean diameter reaching 50–58 cm. Maximum diameters trees (70–80 cm) were represented by 1–4 stems per hectare. The values of the wood-specific gravity of standing trees were around 0.370–0.380 g.cm−3, and varied from 0.302 to 0.523 g.cm−3. Microscopically, our results point out that gap formation is a continuous long-lasting process, starting while canopy trees are living. We observed early signs of wood degradation and bacteria, possibly associated with bark beetles, that induce a strong effect when attacking living trees with vigorous defenses. New information about the initial phase of gap formation has provided a basis for the objective proposal of intervals and intensities of interventions, designed to promote a diversified structure and the long-term ecological stability of the mountain spruce stands in changing climate conditions. Full article
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17 pages, 2946 KiB  
Article
Influence of Forest Management on the Sustainability of Community Areas in Northern Inland Portugal: A Simulated Case Study Assessment
by André Sandim, Dalila Araújo, Teresa Fonseca and Maria Emília Silva
Sustainability 2024, 16(18), 8006; https://doi.org/10.3390/su16188006 - 13 Sep 2024
Cited by 1 | Viewed by 1449
Abstract
The northern inland region of Portugal has experienced significant population decline due to the exodus of younger generations and an aging population. This has led to the abandonment of traditional activities in these territories, contributing to territorial abandonment, degradation of local economic conditions, [...] Read more.
The northern inland region of Portugal has experienced significant population decline due to the exodus of younger generations and an aging population. This has led to the abandonment of traditional activities in these territories, contributing to territorial abandonment, degradation of local economic conditions, increased social vulnerability, and a heightened risk of rural fires. The presence of communal lands, known as “baldios”, is an important facilitator for implementing actions that revitalize local villages, making them more attractive to the community. Forests, which are abundant in the baldios of northern inland Portugal, have the potential to generate environmental, social, and economic value through carbon sequestration, job creation, population stabilization, and wealth generation in the villages. However, the viability of this asset as a driver for sustainable development depends on the forest management model implemented. This case study aims to demonstrate that different forest management models have varied impacts on sustainability indicators, particularly economic and environmental sustainability. Based on naturally regenerated forests in the Carvalhelhos baldio in the Tâmega Valley region, data were collected to simulate in software four management scenarios, varying the number (0 to 4) and age of thinnings until the final cut. The simulation allowed for the calculation of the following economic indicators: Internal Rate of Return (IRR), Net Present Value (NPV), and Net Profitability Index (NPI), as well as environmental indicators related to carbon capture and accumulation, such as Gross Carbon Accumulation, Net Carbon Accumulation, Carbon accumulated in dead and suppressed trees, and carbon balance per management model. The simulations indicate that, for the studied area, Scenario 2, which involves only one thinning, yielded the highest total wood volume (cubic meters per hectare) over the cycle, making it the most suitable for biomass production. Meanwhile, Scenario 4, with three thinnings, showed the best results for individual volume (cubic meters per tree), making it more suitable for producing higher-value logs. Scenario 5 presented the best economic results and carbon capture. In all simulations, Scenario 1 showed the worst performance in the analyzed indicators. It was found that the indicators varied among the studied crop plans, highlighting that the adoption of a silvicultural regime depends on the forest characteristics, objectives, exploitation conditions, and local population sensitivity to regional priorities. Full article
(This article belongs to the Section Sustainable Forestry)
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19 pages, 7596 KiB  
Article
Evaluation of the Effect of Soil Water Conditions on the Development and Water Requirements of Adult Oil Palm (Elaeis guineensis Jacq.) in the Northern Region of Colombia
by Tulia Delgado, Greydy Ladino and Nolver Arias
Agronomy 2024, 14(9), 1976; https://doi.org/10.3390/agronomy14091976 - 1 Sep 2024
Cited by 1 | Viewed by 2033
Abstract
Sustainable water management is a key approach for enhancing the productivity of oil palm trees while addressing the impacts of climate change and variability. Determining the water needs of a crop is crucial for the appropriate application of water. This research was carried [...] Read more.
Sustainable water management is a key approach for enhancing the productivity of oil palm trees while addressing the impacts of climate change and variability. Determining the water needs of a crop is crucial for the appropriate application of water. This research was carried out in two plantations in Agustín Codazzi, Colombia, using a completely randomized design. This study involved examining the impacts of five different water conditions (50, 150, 300, 450, and 600 L per day) on the growth and yields of mature oil palm trees (aged 10–17 years), and their water consumption was calculated using the water balance method. The results indicated that the crop was negatively affected by daily water applications of 300, 150, and 50 L per day, showing statistically significant differences (p < 0.05) when compared to the 450 and 600 L per day treatments, particularly in terms of leaf emergence, leaf area index, and yield (tons per hectare). The 50 L per day treatment resulted in the most substantial decrease in yield (around 26%), primarily attributed to a reduction in the number of bunches. The most favorable crop responses were observed with water applications of 450 and 600 L per day, aligning with the crop’s potential evapotranspiration values (ranging between 5.4 and 5.7 mm per day) and yielding crop coefficients of 0.88 and 0.9, respectively. Notably, these values varied between dry and rainy seasons, peaking between December and March. Full article
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12 pages, 2787 KiB  
Article
Simultaneous Models for the Estimation of Main Forest Parameters Based on Airborne LiDAR Data
by Wentao Zou, Weisheng Zeng and Xiangnan Sun
Forests 2024, 15(5), 775; https://doi.org/10.3390/f15050775 - 28 Apr 2024
Viewed by 1413
Abstract
This study aimed to develop simultaneous models with universal applicability for the estimation of the main factors of forest stands based on airborne LiDAR data and to provide a reference for standardizing the approach and evaluation indices of main forest factor modeling. Using [...] Read more.
This study aimed to develop simultaneous models with universal applicability for the estimation of the main factors of forest stands based on airborne LiDAR data and to provide a reference for standardizing the approach and evaluation indices of main forest factor modeling. Using airborne LiDAR and field survey data from 190 sample plots in spruce (Picea spp.), fir (Abies spp.), and spruce–fir mixed forests in Northeast China, the simultaneous models for estimating the main factors of forest stands were developed. To develop the models, the relationships between mean tree height, stand basal area, stand volume, and the main metrics of the LiDAR data and the correlations between eight quantitative factors of forest stands were considered, and the error-in-variable simultaneous equations approach was employed to fit the models. The results showed that the mean prediction errors (MPEs) of eight forest stand factors estimated by the simultaneous models were mostly within 5%, and only the MPE of the number of trees per hectare exceeded 5%. The mean percentage standard errors (MPSEs) of the estimates, including the mean diameter at the breast height (DBH), mean tree height, and mean dominant tree height, were within 15%; the MPSEs of the estimates of the stand basal area, volume, biomass, and carbon stock per hectare were within 25%; and only the MPSE of the estimated number of trees per hectare exceeded 30%. The coefficients of determination (R2) of the core prediction models for the volume, biomass, and carbon storage were all greater than 0.7. It can be concluded that estimating the main factors of forest stands based on the combination of LiDAR and field survey data is technically feasible, and the simultaneous models developed in this study for the estimation of the eight main stand factors of spruce–fir forests can meet the precision requirements of forest resource inventory, except for the number of trees, indicating that the models can be applied in practice. Full article
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15 pages, 2621 KiB  
Article
Woody Species Composition, Stand Structure and Regeneration Status of Londiani Forest in Kenya
by Evalyne Kosgey Chepkoech, Humphrey Agevi, Henry Lung’ayia and Harrison Mugatsia Tsingalia
Forests 2024, 15(4), 653; https://doi.org/10.3390/f15040653 - 3 Apr 2024
Cited by 1 | Viewed by 1887
Abstract
Tropical forests provide habitats for diverse flora and fauna, in addition to playing a crucial role in climate regulation. They are being recognized for their roles as nature-based solutions to many sustainable development challenges, as shown by increased political commitment and global promises [...] Read more.
Tropical forests provide habitats for diverse flora and fauna, in addition to playing a crucial role in climate regulation. They are being recognized for their roles as nature-based solutions to many sustainable development challenges, as shown by increased political commitment and global promises to reduce the rates of deforestation and boost the restoration of degraded forest ecosystems. Understanding tropical forest dynamics and their conservation status is therefore important. This study analysed the forest stand structure, the tree species composition and the regeneration status of Londiani Forest. In the three blocks of Londiani Forest, which are Kedowa, Chebewor and Londiani, belt transects that were 25 m wide and 1 km long were established. At every 200 m along the transects, 25 m × 25 m quadrats were set up in which an inventory of all the tree species was determined. Diameter tape was used to measure the diameter at breast height (DBH) 1.3 m above the ground. With the use of a Suunto angular clinometer, the tree height was measured. A nested 5 m × 5 m quadrat within the 25 m × 25 m quadrat was used to sample the saplings, while a 1m × 1 m quadrat was used to sample the seedlings. The quantities of seedlings and saplings were used to determine the state of regeneration. The data were entered into Microsoft Excel. The total stem density, species density, basal area, species basal area, relative density and species diversity were determined and extrapolated per hectare. A total of 1308 distinct trees from 34 different species and 24 families were counted. Kedowa recorded the highest (27) species richness, followed by Chebewor (19) and then Londiani (14). There was a statistically significant difference in the species richness among the three forest blocks (p < 0.05). Within the three forest blocks, there were no statistically significant variations in the basal area distribution (p > 0.005) or in the mean DBH (F = 0.560; p = 0.729) or height class distribution (F = 0.821; p = 0.558). There was a statistically significant difference in the stem density (F = 12.22; p = 0.005) and woody species diversity (F = 0.32; p = 0.001) within the three forests blocks. The similarity index ranged from 0.34–0.47. The presence of substantial numbers of seedlings and saplings in all forest blocks was an indication that there was regeneration. Full article
(This article belongs to the Special Issue Ecological Forestry and Restoration)
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14 pages, 261 KiB  
Article
Olive Performance under the Soil Application of Humic Acid and the Spraying of Titanium and Zinc Nanoparticles under Soil Salinity Stress
by Adel M. Al-Saif, Lidia Sas-Paszt and Walid F. A. Mosa
Horticulturae 2024, 10(3), 295; https://doi.org/10.3390/horticulturae10030295 - 19 Mar 2024
Cited by 5 | Viewed by 2004
Abstract
Salinity is a major social, economic, and environmental menace in climates with low rainfall and high evapotranspiration, and it influences plant growth and causes restriction to crop production in the world. Additionally, under salinity stress, numerous physiological processes such as photosynthesis, biomass accumulation, [...] Read more.
Salinity is a major social, economic, and environmental menace in climates with low rainfall and high evapotranspiration, and it influences plant growth and causes restriction to crop production in the world. Additionally, under salinity stress, numerous physiological processes such as photosynthesis, biomass accumulation, and photosynthate transfer are also harshly lessened, and it also limits the absorption of adequate water by plants and leads to a dimension in plant water status. Therefore, the current study was conducted to investigate the soil application of humic acid (HA) at 0, 0.5, 1 and 2 kg/tree alone or in combination with the foliar spraying of 0 mg ZnO2 + 0 mg TiO2, 200 mg ZnO2 + 60 mg TiO2 and/or 300 mg ZnO2 + 80 mg TiO2 through the two successive seasons 2022 and 2023. The results demonstrated that the use of HA alone or in combination with the spraying of TiO2 and ZnO2 greatly improved the leaf chlorophyll, flower number, fruit set percentages, fruit yields in kg or in ton per hectare, fruit weight, fruit size, and fruit firmness. Additionally, the same used treatments greatly improved the fruit content from TSS and oil percentages and also the leaf mineral content from N, P and K, while they minimized the fruit drop percentage and fruit moisture content as compared to control. The most positive influence was observed with the soil implementation of 2 kg HA combined with 300 mg ZnO2 + 80 mg TiO2 in the two experimental seasons. Full article
(This article belongs to the Special Issue Biostimulants Application in Horticultural Crops)
19 pages, 4102 KiB  
Article
Urban Green Development and Resilient Cities: A First Insight into Urban Forest Planning in Italy
by Luca Battisti, Fabrizio Aimar, Giovanni Giacco and Marco Devecchi
Sustainability 2023, 15(15), 12085; https://doi.org/10.3390/su151512085 - 7 Aug 2023
Cited by 15 | Viewed by 3449
Abstract
The research proposes an application of a modification of the 3–30–300 rule to identify areas that require Urban Forestry implementation in small and medium-sized Roman and/or medieval urban areas. The selected case study is that of Asti in Piedmont, Italy. An open source, [...] Read more.
The research proposes an application of a modification of the 3–30–300 rule to identify areas that require Urban Forestry implementation in small and medium-sized Roman and/or medieval urban areas. The selected case study is that of Asti in Piedmont, Italy. An open source, cross-platform desktop geographic information system is used to process geospatial datasets via qualitative analyses of electoral sections (or wards). An analysis of the number and distribution of trees around each building is performed, in addition to the calculation of tree canopy cover and distance between buildings and green spaces. Findings reveal that 64 out of 70 wards have an average of at least three trees per building and sufficient green areas of at least 0.5 hectares within 300 m of the buildings. Additionally, the tree canopy cover ranges from approximately 0.6% (lowest) to about 55% (highest) for the electoral sections. Lastly, findings suggest that the highly built-up urban fabric in these areas may significantly affect the availability and quality of green spaces. In conclusion, the case study proves the benefits of applying the 3–30–300 rule to small and medium-sized urban areas using an integrated assessment approach based on nature-based solutions and ecosystem services. Full article
(This article belongs to the Special Issue Advances in Urban Green Development and Resilient Cities)
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27 pages, 9410 KiB  
Article
New Technologies for Expedited Forest Inventory Using Smartphone Applications
by André Sandim, Mariana Amaro, Maria Emilia Silva, Jorge Cunha, Susana Morais, Alexandra Marques, André Ferreira, José Luis Lousada and Teresa Fonseca
Forests 2023, 14(8), 1553; https://doi.org/10.3390/f14081553 - 29 Jul 2023
Cited by 7 | Viewed by 4390
Abstract
The forest inventory plays a crucial role in forest management planning, and it is the first step in planning actions for forest production. However, conducting an inventory can be expensive and complex. Forest inventory applications on smartphones have emerged as an alternative to [...] Read more.
The forest inventory plays a crucial role in forest management planning, and it is the first step in planning actions for forest production. However, conducting an inventory can be expensive and complex. Forest inventory applications on smartphones have emerged as an alternative to traditional methods and they aim to make field data collection more accessible to non-professionals while ensuring accuracy in determining the volume of wood in a given area. This study evaluates the effectiveness of the Katam, Arboreal, and Trestima applications compared to traditional data collection methods. The study focuses on assessing the stand density and diameter of sampled trees—two key variables that are assessed in forest inventories. Two species, maritime pine (Pinus pinaster Aiton) and Eucalyptus spp. (mainly Eucalyptus globulus and Eucalyptus nitens), were used to evaluate the performance of the methods, with assessments performed in the stands of diverse dendrometric characteristics, specifically those regarding the tree age, stand density, and topographic conditions (flat or sloping terrain). For the purpose of comparison, goodness-of-fit statistics (R2, RMSE, and BIAS) were calculated, and an analysis of the diameter distribution and comparison of the mean diameter, number of trees per hectare, and basal area were performed. In general, the applications were accurate, and the average basal area did not differ significantly from the traditional method. The diameter measurements showed good accuracy. The accuracy of the applications varied depending on the terrain and forest characteristics, with the applications performing better in areas with flat terrain, as well as with older forests that were regular and had low under-cover density. In contrast, the applications performed worse in younger, irregular forests with sloping terrain, high tree density, and those with a great deal of understory vegetation. The applications still need to evolve in evaluating other important variables (such as tree height or volume) as they are currently estimated from auxiliary variables through mathematical equations. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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24 pages, 7690 KiB  
Article
Mango Fruit Fly Trap Detection Using Different Wireless Communications
by Federico Hahn, Salvador Valle, Roberto Rendón, Oneyda Oyorzabal and Alondra Astudillo
Agronomy 2023, 13(7), 1736; https://doi.org/10.3390/agronomy13071736 - 28 Jun 2023
Cited by 2 | Viewed by 3769
Abstract
Fruit flies cause production losses in mango orchards affecting fruit quality. A National Campaign against Fruit Flies (NCFF) evaluates farm status using the fruit flies per trap per day index (FTD). Traps with attractant are installed manually within orchards in Mexico, but counting [...] Read more.
Fruit flies cause production losses in mango orchards affecting fruit quality. A National Campaign against Fruit Flies (NCFF) evaluates farm status using the fruit flies per trap per day index (FTD). Traps with attractant are installed manually within orchards in Mexico, but counting the flies trapped every week requires excessive numbers of trained personal. Electronic traps (e-traps) use sensors to monitor fruit fly population, saving labor and obtaining the real-time orchard infestation. The objective of this work was to acquire an image within a e-trap at 17:00 when an insect was detected and binarize the information in real-time to count the number of flies. Each e-trap was implemented with a polyethylene PET bottle screwed to a tap containing an ESP32-CAM camera. E-traps from several hectares of mango trees were sampled and transmitted through WSN wireless sensor networks. This original system presents a star topology network within each hectare with the long range LoRa transceiver at the central tower. It receives the fly count from five e-traps and finally transmits data to the house tower end point. Another contribution of this research was the use of a DJI mini2 for acquiring the e-trap data, and the 8-ha flight took 15 min and 35 s. This period can be reduced if the drone flies higher. Full article
(This article belongs to the Special Issue AI, Sensors and Robotics for Smart Agriculture)
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12 pages, 2023 KiB  
Article
Preliminary Results on the Effects of Initial Stand Density and Supplemental Irrigation on Biomass of Eucalyptus camaldulensis Dehn. Grown as a Short Rotation Woody Crop under Semi-Arid Conditions
by Yiftach Vaknin and Leonid Korol
Agronomy 2023, 13(5), 1216; https://doi.org/10.3390/agronomy13051216 - 25 Apr 2023
Cited by 1 | Viewed by 1681
Abstract
Most short rotation coppice (SRC) plantations are grown in temperate, subtropical, and tropical areas where land availability is limited. Very little is known about the potential biomass yield of Eucalyptus camaldulensis grown as SRC under semi-arid conditions with supplemental irrigation. Our objective was [...] Read more.
Most short rotation coppice (SRC) plantations are grown in temperate, subtropical, and tropical areas where land availability is limited. Very little is known about the potential biomass yield of Eucalyptus camaldulensis grown as SRC under semi-arid conditions with supplemental irrigation. Our objective was to maximize biomass production of E. camaldulensis under semi-arid conditions as a feedstock for biofuels by optimizing initial stem density (ISD) and irrigation amount. We tested the effects of four densities of 2500, 10,000, 40,000, and 160,000 stems per hectare, and supplemental irrigation of 100% or 200% of potential evapotranspiration on tree growth and biomass production. Our results showed that under semi-arid conditions and supplemental irrigation, trees grew rapidly and accumulated biomass at a rate equal to or exceeding that in tropical regions. As ISD increased, individual trees grew slightly taller, became much narrower, and had fewer stems. We concluded that competition for resources such as light and nutrients increased with ISD, resulting in significantly lower biomass accumulation by individual trees. However, the significantly greater number of individuals with increasing ISD was responsible for the higher biomass production per hectare, allowing us to achieve exceptionally high annual yields of eucalypt biomass under semi-arid conditions after three annual coppicing cycles. Full article
(This article belongs to the Section Water Use and Irrigation)
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16 pages, 1480 KiB  
Article
Functional Traits and Local Environmental Conditions Determine Tropical Rain Forest Types at Microscale Level in Southern Ecuador
by Omar Cabrera, Pablo Ramón, Bernd Stimm, Sven Gunter and Reinhard Mosandl
Diversity 2023, 15(3), 420; https://doi.org/10.3390/d15030420 - 13 Mar 2023
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Abstract
The main objective of this study was to determine the heterogeneity of tropical mountain rain forests along a micro-altitudinal gradient scale, integrating species functional traits in the separation of communities. To achieve this, a forest area of 13 ha in the Biological Reserve [...] Read more.
The main objective of this study was to determine the heterogeneity of tropical mountain rain forests along a micro-altitudinal gradient scale, integrating species functional traits in the separation of communities. To achieve this, a forest area of 13 ha in the Biological Reserve of San Francisco was monitored. First, we performed non-metric multidimensional analyses, and afterwards, we looked for correlations between plot altitude and characteristics of the forest (basal area, the number of species, the number of trees ≥20 cm diameter at breast height, per hectare, the forest canopy opening) were associated. To determine which characteristics significantly influence the separation of forest “communities”, we used a multivariate canonical correspondence analysis (CCA). Finally, we carried out the “Four Corners” analysis, combining abundance matrices, traits and environmental variables. We confirmed that the altitude and some associated characteristics are the key factors for the formation of two forest types. In addition, we determined that the inclusion of species functional traits confirms the separation of forest communities, and that elevation and its associated environmental variables function over relatively small areas and scales. Full article
(This article belongs to the Special Issue Forest Management and Biodiversity Conservation)
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