Site Variability in Fibers, Vessels, and Ring Width of Robinia pseudoacacia L. Wood: A Case Study in Hungary
1
Faculty of Wood Engineering and Creative Industries, University of Sopron, Bajcsy-Zs. Str. 4, 9400 Sopron, Hungary
2
Faculty of Forest Sciences and Technology, University of Gezira, Al Gezira, Wad Madani 22211, Sudan
*
Author to whom correspondence should be addressed.
Forests 2025, 16(5), 807; https://doi.org/10.3390/f16050807
Submission received: 16 March 2025
/
Revised: 30 April 2025
/
Accepted: 8 May 2025
/
Published: 12 May 2025
(This article belongs to the Section Wood Science and Forest Products)
Abstract
:The black locust tree is a plantation-grown species that occupies a large area in Hungary. Due to variations in the growth environment of trees across different locations, the anatomical features of wood may differ. This study investigated the variability in fiber properties (fiber length, width, wall thickness, vessel length, and width) and growth rate of Robinia pseudoacacia L. from five counties and in three specific growing conditions. The parameters were investigated based on a sample of discs taken from the trees at breast height. The statistical analysis revealed significant differences in wood fiber and vessel dimensions, as well as ring width, between counties and growth conditions. Nearly all examined parameters showed the lowest values in Bács-Kiskun County, whereas the highest values were observed in Szabolcs-Szatmár-Bereg and Vas. Regarding the growth conditions, wood in poor growth conditions (mixed trees) and good growth conditions produced superior wood fiber properties and ring widths.
1. Introduction
Rising temperatures, changing precipitation patterns, and increasing frequency of extreme events caused by climate change modify ecosystems all around the world [1]. These developments have a major effect on tree growth, therefore influencing survival, production, and distribution [2]. Depending on tree species, variations in growth conditions obviously influence the anatomical structure of the wood; consequently, its characteristics vary [3].
Black locust (Robinia pseudoacacia L.) is a hardwood species native to eastern North America and has been imported to Europe since 1601. All sub-Mediterranean and temperate climates have adopted it. It is drought-resilient and flourishes in regions with annual precipitation as low as 500–550 mm [4]. In Hungary, it is located in the center, northeast, south, and southwest of Trans Danubia. The first major black locust forests were planted at the beginning of the 18th century to stabilize the wind-blown, sandy soil [5,6]. After that, it was planted in several locations with varying soil characteristics [7]. It is a valuable tree, contributing to sectors of the economy and ecology [8,9,10].
The wood of Robinia pseudoacacia L. is characterized by ring porosity, featuring large vessels arranged circularly and exhibiting a heterogeneous structure [11]. The wood properties vary between trees and within each tree, both radially and tangentially [12,13,14,15,16]. Environmental influences, genetic differences, tree age, and site-specific growth circumstances often govern these variations [17,18,19,20,21,22]. Researchers have noted that changes in water availability, heat stress, and carbon dioxide levels in the air could affect cambial activity and xylem development, leading to changes in wood structure and quality [23,24].
The quality of wood is essential in assessing the usability and worth of timber species across diverse uses, including construction and fine woodworking. Fiber dimensions are among the parameters used in wood evaluation [25,26,27].
Therefore, we assume that the wood anatomical structure and growth rate of Robinia pseudoacacia may vary. While characteristics have been looked at before in countries like Greece, Belgium, and Hungary [11,28,29], our study is distinctive since it looks at the variations in wood anatomical features between several sites and growth conditions in a wide area within Hungary.
The specific aim of this research was to investigate the variability in wood fibers, vessels, and ring width in Robinia pseudoacacia L. growing in five counties and under three distinctive growth conditions.
2. Materials and Methods
The wood material was collected from eleven spots, which represent five Hungarian counties (Figure 1). Table 1 highlights the information regarding locations, number of discs used, diameter at breast height, tree growth conditions, and coordinates.
The sites studied were classified into three growth conditions based on soil qualities according to [30,31]. Precisely, they were classified as GGC (good growth conditions) sites, which had good-quality soil (rusty brown forest sandy soil of about 60–100 cm depth, high fertility, good structure, balanced nutrient levels, adequate drainage, and balanced pH between 6 and 6–7); PGCs (poor growth conditions), characterized by poor-quality soil (rusty brown forest loamy soil with stagnant water and about 40–100 cm depth, low fertility, poor structure, compaction, waterlogging, and high salinity); and MPGCs (mixed species in poor growth conditions). We did not use hybrid varieties to eliminate the resulting variation.
2.1. Sampling
We extracted discs with a thickness of 4 cm from each log at breast height (130–140 cm). Then, a 2 cm wide strip was taken from bark to bark and divided subsequently into two strips (each 2 cm in width and 2 cm in thickness). One strip was used to determine the wood fiber length (FL), width (FW), wall thickness (FWT), lumen diameter (LD), and vessel length (VL) and width (VW). The second strip was used to measure the annual ring width (Figure 2).
2.2. Measurements of Fiber Parameters
Small pieces were extracted from various positions on the strip. The pieces were placed in test tubes and macerated using a mixed solution of equal volumes of glacial acetic acid (98%) (Avantor; VWR International Kft) and hydrogen peroxide (30%) (ES Lab Hungary Ltd.), then heated to 65 °C for 24–28 h in a water bath. We then washed the macerated pieces with distilled water [32]. Afterwards, a small amount of the macerated fibers was placed on glass microscope slides. The fiber and vessel properties were observed using a light microscope equipped with a digital camera (Nikon Eclipse, Nikon, Japan) and ProScan III software (V31XYZE/D, Prior Scientific Instruments Ltd., Wilbraham Road, Fulbourn, Cambridgeshire, CB21 5ET, UK). Separately, from each disc, a total of fifty wood FL (mm) and twenty-five FW (µm), FWT (µm), LD (µm), VL (µm), and VD (µm) measurements were taken.
2.3. Ring Width Measurements
The wood strips were polished using sandpaper to smooth the rough surfaces. The smooth strips were scanned using a scanner (CanonScan LiDE 110, Canon, Japan) [33]. Then, the annual ring widths were measured with ImageJ software (V1.54d, National Institutes of Health, MD, USA).
2.4. Data Analysis
All data were analyzed using R statistical software (V4.3.2 (2023-10-31 ucrt)). At first, the Shapiro–Wilk test was used to check if the data distribution was normal. The test result revealed that no variable follows a normal distribution. Based on that, we used the Kruskal–Wallis nonparametric test to determine the statistical significance instead of ANOVA. Only when the Kruskal–Wallis test revealed significant differences did we use the post hoc test, Dunn pairwise comparison (the Bonferroni method), to identify the differences between groups.
3. Results
Across all counties, wood FL varied between 1.04 and 1.11 mm, while FW, FWT, and LD varied between 15.5 and 18.4 µm, 2.55 and 3.76 µm, and 8.19 and 9.98 µm, respectively. The VL, VW, and RW varied from 118.9 to 126 µm, 191 to 223 µm, and 2.15 to 3.90 mm, respectively (Table 2). The VL and VW dimensions were measured from both early and late wood, resulting in higher standard deviations.
A Kruskal–Wallis test revealed significant differences in FL (kw-squared = 12.4, p = 0.01), FW (kw-squared = 30.21, p < 0.0001), FWT (kw-squared = 85.66, p < 0.0001), VW (kw-squared = 14.31, p = 0.01), and RW (kw-squared = 195.77, p < 0.0001). In contrast, no significant differences were observed for LD (kw-squared = 8.59; p = 0.08) or VL (kw-squared = 3.87, p = 0.42).
The Dunn test (Table 3) showed that only Szabolcs-Szatmár-Bereg had a significantly higher median FL (1.09 mm) than Vas County (1.02 mm). Likewise, there was a significant difference in VW between Bács-Kiskun and Szabolcs-Szatmár-Bereg. The median values of FW (15.93 µm), FWT (2.78 µm), and RW (1.19 mm) were significantly lower in Bács-Kiskun County than in the other counties.
As shown in Table 4, the simple statistics for wood fibers, vessels, and annual ring width under the three growth conditions are summarized. The result shows that GGCs (good growth conditions) produced the longest FL (1.12 mm) and VL (125 µm) and the widest VW (227 µm). Similarly, the FW, FWT, and LD parameters were highest in MPGCs, poor growth conditions for mixed species. However, in the case of PGCs, most of the parameters were the lowest compared to those observed in other growth conditions.
There were differences in FL (kw-squared = 25, p < 0.0001), FW (kw-squared = 8.76, p < 0.0001), FWT (kw-squared = 18.50, p = 0.0001), VW (kw-squared = 15.64, p = 0.0001), and RW (kw-squared = 56.58, p = 0.0001) based on the growth conditions, as shown by the Kruskal–Wallis test. The statistics for LD and VL did not show significant differences (kw-squared = 5.81, p = 0.05 and kw-squared = 5.17, p = 0.08, respectively). The analysis of the statistics for LD and VL did not significantly vary (kw-squared = 5.81, p = 0.05 and kw-squared = 5.17, p = 0.08, respectively). The significant differences (Dunn test) between group conditions are shown in Table 5.
The variability in the annual ring width from pith to bark for each county is shown in Figure 3. The curve shows that Bács-Kiskun County has the narrowest annual rings, while those of Szabolcs-Szatmár-Bereg and Vas Counties show the widest width.
Regarding growing conditions, MPGCs (mixed trees) and GGCs (good growth conditions) showed the greatest annual ring widths, respectively. PGCs (poor growth conditions), on the other hand, displayed the narrowest widths (Figure 4).
4. Discussion
Robinia pseudoacacia L. trees grow widely around the world, including in Hungary [34]. They have been used for several important purposes [7,35]. In our study, fibers, vessels, and ring width were investigated in several counties and under different growth conditions. These investigated parameters are crucial for the evaluation of wood characteristics [3,25]. Fibers play an important role in determining the mechanical properties of wood, such as strength, flexibility, and durability, which are necessary for applications in construction, furniture production, and tool handles. The characteristics of the vessel influence the porosity and permeability of the wood, which are critical in drying, seasoning, and preservative treatments. In addition, ring width is an indicator of growth rate, which is related to wood density and overall mechanical performance [36].
Regarding the variability between sites, our results indicate that significant differences in FL occurred only between Szabolcs-Szatmár-Bereg and Vas Counties, and similarly between Bács-Kiskun and Szabolcs-Szatmár-Bereg for VW. Significant differences were also observed between several counties for FW, FWT, VW, and RW (Table 3). In contrast, there were no differences for LD or VL in any counties. We found that all counties had almost similar characteristics, except Bács-Kiskun County, which had the lowest values for FW, FWT, and RW and the highest VW, while Szabolcs-Szatmár-Bereg and Vas Counties had the best characteristics.
Previous studies mentioned that there are many factors that cause variations in wood anatomical features between sites. These factors include the type of soil and its corresponding nutrient and moisture availability [37]. For instance, water availability significantly determines wood vessel and fiber sizes specifically in Robinia pseudoacacia L. [38]. In dry climates or areas with variable water availability, plants typically develop narrower vessels with thicker walls, which reduces the probability of embolism during drought conditions [39]. Conversely, areas with increased and stable water availability can produce larger vessels and fiber diameters [40,41]. Also, under favorable growing conditions, the ring widths increase [42,43,44,45]. In addition, genetic adaptations likely interact with environmental pressures to alter traits such as fiber wall thickness, vessel diameter, and ring width in response to specific site conditions [46]. Significant variations in fiber properties and growth rings of Robinia pseudoacacia L. wood were observed within a single growth ring [15] and within the radial direction (between early and late wood) [11,47]. Furthermore, regarding tree ages, old trees had longer fiber lengths than the youngest trees [48,49]. In comparison to our findings, the fiber length ranged between 1.04 and 1.11 mm, which is higher than values given by [48] and lower than values reported by [49] for trees aged 60 and 71 years.
In terms of growth conditions, GGCs—good growth conditions—showed the greatest fiber, vessel, and ring widths compared to PGCs and MPGCs—poor and mixed growth conditions. Interestingly, the MPGCs had better parameters than PGCs (poor growth conditions), which indicated that the mixed trees have better properties because of different root structures and canopies, allowing for more efficient use of sunlight, water, and nutrients. These reduce the competition and promote better growth conditions, which can enhance fiber properties and growth rate. Previous research has indicated that high-quality sites yield high-quality timber from Robinia pseudoacacia L. [7]. Our findings confirmed this due to the long fibers and wide ring widths.
The ring width patterns in our study resemble the curves identified by [11,13,28]. The widths of the annual rings decreased from pith to bark, which is attributed to the age of the cambium (ring width diminished as age increased). Other species, such as Alnus glutinosa, also display a comparable pattern [50].
5. Conclusions
Across all counties, we observed significant differences in FL only between Szabolcs-Szatmár-Bereg and Vas Counties, as well as between Bács-Kiskun and Szabolcs-Szatmár-Bereg, in terms of VW. In contrast, there were notable variations in FW, FWT, and RW between many counties. But there were no significant differences in LD and VL. Furthermore, we found that GGCs and MPGCs produce the best fiber properties and the widest ring widths. Future studies will focus on chemical, physical, and mechanical properties to provide additional information regarding these areas of study and growth conditions.
Author Contributions
Conceptualization, F.A.A.A.Y. and R.N.; methodology, F.A.A.A.Y.; validation, F.A.A.A.Y. and R.N.; formal analysis, F.A.A.A.Y.; investigation, F.A.A.A.Y. and M.B. (Miklós Bak); resources, M.B. (Mátyás Báder) and R.N.; writing—original draft preparation, F.A.A.A.Y.; writing—review and editing, F.A.A.A.Y., M.B. (Mátyás Báder), M.B. (Miklós Bak), and R.N.; visualization, F.A.A.A.Y.; supervision, R.N.; project administration, M.B. (Mátyás Báder) and R.N.; funding acquisition, R.N. All authors have read and agreed to the published version of the manuscript.
Funding
This article was made in frame of the project TKP2021-NKTA-43, which has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.
Data Availability Statement
The data presented in this study are available on request from the corresponding author.
Acknowledgments
The authors thank Imre Horváth for his help with log transport and wood processing.
Conflicts of Interest
The authors declare no conflicts of interest.
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Figure 1.
Study area map with specific locations for wood sample collection within the County by name.
Figure 1.
Study area map with specific locations for wood sample collection within the County by name.
Figure 2.
Images for (a) wood material; (b) disc; (c) strips from bark to bark; (d) fiber length (4× lens); (e) fiber width (10× lens); and (f) vessel dimensions (40× lens).
Figure 2.
Images for (a) wood material; (b) disc; (c) strips from bark to bark; (d) fiber length (4× lens); (e) fiber width (10× lens); and (f) vessel dimensions (40× lens).
Figure 3.
Variability among counties in annual ring width from pith to bark of wood of Robinia pseudoacacia L. wood.
Figure 3.
Variability among counties in annual ring width from pith to bark of wood of Robinia pseudoacacia L. wood.
Figure 4.
Variability among growth conditions in width of annual rings from pith to bark of Robinia pseudoacacia L. wood.
Figure 4.
Variability among growth conditions in width of annual rings from pith to bark of Robinia pseudoacacia L. wood.
Table 1.
Counties, sites, numbers of discs, average diameters at breast height (DBH), growth conditions, and coordinates. Abbreviations: GGC—good growth condition; PGC—poor growth condition; MPGC—poor growth condition (mixed species). The numbers 31 and 33 in Ófehértó refer to the compartment number inside the forest.
Table 1.
Counties, sites, numbers of discs, average diameters at breast height (DBH), growth conditions, and coordinates. Abbreviations: GGC—good growth condition; PGC—poor growth condition; MPGC—poor growth condition (mixed species). The numbers 31 and 33 in Ófehértó refer to the compartment number inside the forest.
| County | Sites Within County | Number of Discs/Sites | Average DBH (cm) | Growth Conditions | Coordinates |
|---|---|---|---|---|---|
| Bács-Kiskun | Balotaszállás | 2 | 24.5 | GGC | 68.6546° N, 10.9105° E |
| Kunfehértó | 3 | 17 | PGC | 67.4622° N, 11.4344° E | |
| Szabolcs-Szatmár-Bereg | Ófehértó 33 | 2 | 26 | GGC | 87.7527° N, 29.1922° E |
| Ófehértó 31 | 2 | 22 | PGC | 87.8676° N, 29.0636° E | |
| Pap | 2 | 26 | GGC | 88.1955° N, 32.1529° E | |
| Baktalórántháza | 2 | 27 | PGC | 87.5568° N, 29.6031° E | |
| Vas | Telekes | 3 | 27 | MPGC | 47.5547° N, 17.9632° E |
| Baranya | Ibafa | 1 | 22 | GGC | 46.0918° N, 17.5459° E |
| Ibafa | 1 | 20 | PGC | ||
| Győr-Moson-Sopron | Iván | 2 | 18 | PGC | 47.44633° N, 16.91224° E |
| Iván | 2 | 27 | GGC |
Table 2.
The descriptive statistics of fibers, vessels, and ring width of Robinia pseudoacacia L. wood across counties.
Table 2.
The descriptive statistics of fibers, vessels, and ring width of Robinia pseudoacacia L. wood across counties.
| County | Statistic | FL (mm) | FW (µm) | FWT (µm) | LD (µm) | VL (µm) | VW (µm) | RW (mm) |
|---|---|---|---|---|---|---|---|---|
| Szabolcs-Szatmár-Bereg | Mean | 1.11 | 17.6 | 3.47 | 8.97 | 139 | 177 | 3.63 |
| Median | 1.09 | 17.50 | 3.80 | 8.18 | 140.85 | 172.31 | 3.12 | |
| Min | 0.81 | 11.87 | 2.13 | 5.24 | 91.07 | 103.61 | 1.54 | |
| Max | 1.42 | 21.82 | 4.83 | 13.30 | 202.76 | 288.95 | 6.34 | |
| Std | 0.130 | 2.288 | 0.674 | 2.13 | 28.6 | 42.9 | 1.34 | |
| Bács Kiskun | Mean | 1.08 | 15.5 | 2.55 | 8.19 | 136 | 242 | 1.25 |
| Median | 1.07 | 15.93 | 2.78 | 9.05 | 128.81 | 271.79 | 1.19 | |
| Min | 0.82 | 12.95 | 1.70 | 5.52 | 100 | 107.97 | 0.30 | |
| Max | 1.39 | 17.63 | 3.33 | 9.84 | 195.76 | 366.73 | 2.68 | |
| Std | 0.117 | 1.31 | 0.332 | 1.91 | 28.1 | 79.9 | 0.72 | |
| Győr-Moson-Sopron | Mean | 1.08 | 17.1 | 3.24 | 8.90 | 118 | 193 | 3.21 |
| Median | 1.06 | 16.86 | 3.60 | 8.29 | 142.71 | 200.03 | 3.02 | |
| Min | 0.83 | 12.47 | 2.24 | 5.69 | 82.14 | 96.69 | 0.98 | |
| Max | 1.37 | 22.96 | 4.44 | 13.13 | 228.55 | 299.64 | 5.95 | |
| Std | 0.139 | 2.71 | 0.596 | 2.15 | 48.5 | 58.7 | 1.28 | |
| Baranya | Mean | 1.06 | 17 | 3.30 | 9.98 | 144 | 188 | 3.11 |
| Median | 1.07 | 16.13 | 3.19 | 8.87 | 150.43 | 184.24 | 3.06 | |
| Min | 0.72 | 11.19 | 2.08 | 5.04 | 91.92 | 124.18 | 1.36 | |
| Max | 1.47 | 23.98 | 4.82 | 16.59 | 194.51 | 283.57 | 5.09 | |
| Std | 0.139 | 3.71 | 0.602 | 2.64 | 39.1 | 48.1 | 1.04 | |
| Vas | Mean | 1.04 | 18.4 | 3.76 | 9.14 | 144 | 179 | 3.68 |
| Median | 1.02 | 18.63 | 3.72 | 8.89 | 142.08 | 171.71 | 3.91 | |
| Min | 0.75 | 13.46 | 2.24 | 5.06 | 92.43 | 141.53 | 1.36 | |
| Max | 1.34 | 22.47 | 5.06 | 13.89 | 196.24 | 209.66 | 6.02 | |
| Std | 0.155 | 2.71 | 0.757 | 2.40 | 31.4 | 26.3 | 1.25 |
Min = minimum; Max = maximum; Std = standard deviation.
Table 3.
Post hoc pairwise comparisons (Bonferroni method) between county groups.
| Parameters | Comparison | Z-Statistic | Adjusted p-Value |
|---|---|---|---|
| FL | Szabolcs-Szatmár-Bereg vs. Vas | 3.12 | 0.008 |
| FW | Bács Kiskun vs. Győr-Moson-Sopron | −2.97 | 0.04 |
| Bács Kiskun vs. Szabolcs-Szatmár-Bereg | −4.55 | 0.0001 | |
| Bács Kiskun vs. Vas | −4.63 | 0.0001 | |
| Baranya vs. Vas | −2.92 | 0.0001 | |
| FWT | Bács Kiskun vs. Baranya | −5.99 | 0.0001 |
| Bács Kiskun vs. Győr-Moson-Sopron | −5.54 | 0.0001 | |
| Bács Kiskun vs. Szabolcs-Szatmár-Bereg | −8.44 | 0.0001 | |
| Bács Kiskun vs. Vas | −7.26 | 0.0001 | |
| VW | Bács Kiskun vs. Szabolcs-Szatmár-Bereg | 3.68 | 0.001 |
| RW | Bács Kiskun vs. Baranya | −7.95 | 0.0001 |
| Bács Kiskun vs. Győr-Moson-Sopron | −7.99 | 0.0001 | |
| Baranya vs. Szabolcs-Szatmár-Bereg | −11.18 | 0.0001 | |
| Baranya vs. Vas | −11 | 0.0001 |
Table 4.
The descriptive statistics of the fiber and vessel properties of Robinia pseudoacacia L. wood grown under GGCs (good growth conditions), PGCs (poor growth conditions), and MPGCs (poor growth conditions (mixed species).
Table 4.
The descriptive statistics of the fiber and vessel properties of Robinia pseudoacacia L. wood grown under GGCs (good growth conditions), PGCs (poor growth conditions), and MPGCs (poor growth conditions (mixed species).
| Growth Conditions | Statistic | FL (mm) | FW (µm) | FWT (µm) | LD (µm) | VL (µm) | VW (µm) | RW (mm) |
|---|---|---|---|---|---|---|---|---|
| GGC | Mean | 1.12 | 16.9 | 3.33 | 8.34 | 125 | 227 | 3.68 |
| Median | 1.11 | 16.87 | 3.21 | 7.98 | 143.61 | 202.98 | 3.34 | |
| Min | 0.80 | 12.32 | 1.70 | 5.04 | 91.92 | 103.61 | 1.05 | |
| Max | 1.42 | 22.96 | 5.20 | 13.32 | 228.55 | 366.73 | 5.67 | |
| Std | 0.139 | 2.87 | 0.745 | 1.97 | 43.6 | 87.9 | 1.25 | |
| PGC | Mean | 1.06 | 17.0 | 3.09 | 8.93 | 118 | 182 | 2.70 |
| Median | 1.05 | 16.29 | 3.05 | 8.86 | 137.04 | 169.94 | 2.74 | |
| Min | 0.81 | 11.19 | 1.65 | 5.09 | 82.14 | 96.69 | 1.43 | |
| Max | 1.39 | 23.98 | 4.82 | 13.80 | 202.76 | 299.64 | 3.81 | |
| Std | 0.119 | 2.93 | 0.582 | 2.18 | 45 | 95.9 | 0.67 | |
| MPGC | Mean | 1.04 | 18.4 | 3.76 | 9.14 | 122 | 215 | 3.68 |
| Median | 1.02 | 18.44 | 3.72 | 8.89 | 142.08 | 171.71 | 3.91 | |
| Min | 0.95 | 13.46 | 2.24 | 5.06 | 92.43 | 141.53 | 1.36 | |
| Max | 1.34 | 22.47 | 5.06 | 13.89 | 196.24 | 209.66 | 6.02 | |
| Std | 0.155 | 2.71 | 0.757 | 2.40 | 42.2 | 78.9 | 1.25 |
Min = minimum; Max = maximum; Std = standard deviation.
Table 5.
Post hoc pairwise comparisons between GGCs (good growth conditions), PGCs (poor growth conditions), and MPGCs (poor growth conditions for mixed trees).
Table 5.
Post hoc pairwise comparisons between GGCs (good growth conditions), PGCs (poor growth conditions), and MPGCs (poor growth conditions for mixed trees).
| Parameter | Comparison | Z-Statistic | Adjusted p-Value |
|---|---|---|---|
| FL | GGC vs. PGC | 4.36 | 0.0001 |
| GGC vs. MPGC | 3.60 | 0.0005 | |
| FW | GGC vs. PMGC | −2.90 | 0.005 |
| MPGC vs. PGC | 2.72 | 0.009 | |
| FWT | GGC vs. MPGC | −262 | 0.01 |
| GGC vs. PGC | 2.50 | 0.01 | |
| MPGC vs. PGC | 4.06 | 0.0001 | |
| VW | GGC vs. PGC | 3.9 | 0.0001 |
| RW | GGC vs. MPGC | −3.89 | 0.0001 |
| GGC vs. PGC | 4.02 | 0.0001 | |
| MPGC vs. PGC | 7.43 | 0.0001 |
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MDPI and ACS Style
Younis, F.A.A.A.; Báder, M.; Bak, M.; Németh, R. Site Variability in Fibers, Vessels, and Ring Width of Robinia pseudoacacia L. Wood: A Case Study in Hungary. Forests 2025, 16, 807. https://doi.org/10.3390/f16050807
AMA Style
Younis FAAA, Báder M, Bak M, Németh R. Site Variability in Fibers, Vessels, and Ring Width of Robinia pseudoacacia L. Wood: A Case Study in Hungary. Forests. 2025; 16(5):807. https://doi.org/10.3390/f16050807
Chicago/Turabian StyleYounis, Fath Alrhman Awad Ahmed, Mátyás Báder, Miklós Bak, and Róbert Németh. 2025. "Site Variability in Fibers, Vessels, and Ring Width of Robinia pseudoacacia L. Wood: A Case Study in Hungary" Forests 16, no. 5: 807. https://doi.org/10.3390/f16050807
APA StyleYounis, F. A. A. A., Báder, M., Bak, M., & Németh, R. (2025). Site Variability in Fibers, Vessels, and Ring Width of Robinia pseudoacacia L. Wood: A Case Study in Hungary. Forests, 16(5), 807. https://doi.org/10.3390/f16050807
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