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The paper provides the results of a detailed analysis of timber volume and the most important crown variables of black locust (Robinia pseudoacacia Linnaeus) based on an experimental plot in southern Hungary. At the age of 20 years the crop trees belonged to different height classes. If the volume of the mean tree from height class I is considered...
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... Indeed, Sumida et al. (2013) supported that DBH is related to the diameter at the base of the live crown, based on 20-year data from Hinoki cypress (Chamaecyparis obtusa) stands. However, DBH has been related mostly to other crown traits, such as crown diameter and width, crown projected area and height of live crown base, in different forest species (Grote 2003, Blanchard et al. 2016, as well as in black locust (Moser et al. 2015, Carl et al. 2017, Rédei et al. 2018. To our knowledge, the relationship between DBH and the diameter at the base of the live crown received little attention (Lockhart et al. 2005), but it has been verified also by our findings (Fig. 6B) and it may be a useful tool to predict Dhlc based on the easily measured DBH. ...
Allometric equations relating trees' vascular system and other stem metrics with foliage area and mass are important to estimate their growth, carbon stocks and interactions with abiotic environment in terms of carbon and water balance. In this study we focused on Robinia pseudoacacia restoration plantations in Greece and aimed at establishing species-specific models to predict foliage leaf area and biomass based on stem traits. In particular, we evaluated stem cross-sectional areas of sapwood, current sapwood and total stem (sap-wood and heartwood), measured at different tree heights, as predictors of leaf area and mass, based on the pipe model theory. Furthermore, we assessed the variation in the ratios of leaf area to different stem cross-sectional areas across the tree profile and we examined the relationships of diameter at breast height (DBH) with diameter at the base of the live crown and with leaf area. Taking into account the trees' DBH distribution according to the planta-tions' inventory, 25 black locust individuals were destructively sampled and the relationships among the studied traits were analyzed by means of multiple and simple linear regression at p<0.001. Foliage dry mass and area were best predicted by total stem cross-sectional area at mid-bole and stump height (R 2 =0.81), followed by current sapwood area at stump height (R 2 =0.74), which outperformed the most often used sapwood area (R 2 =0.70). DBH was also reliably estimating tree leaf area (R 2 =0.72) but was less precise, compared to total cross-sectional area, while it was a useful proxy of diameter at the base of the live crown (R 2 =0.80). In line with the pipe model theory, the ratio of leaf area to total cross-sectional area declined across the canopy basipetally, but only when total cross-sectional area was considered. Deviations from the sap-wood-foliage functions described by the pipe model theory may be due to the small sample size and the variability in tree size in such developing restoration plantations. The produced species-specific relationships between stem and foliage metrics may be a useful tool to predict the carbon sequestration and climate change adaptation potential of black locust restoration plantations, which are often characterized by harsh site conditions.
... In contrast, lightdemanding crops are grown outside the shaded area and are used in many agroforestry plantations. This strategy enables farmers to make the most of their space, benefiting from the trees planted and eliminating the need to provide shade to the plants by other means [87,88]. In addition to this, it has also been noted that understocking may also have a positive impact on stand growth, i.e., by reducing the allocation of soil water using trees; thinning of the stand can lead to increased tree growth, which can provide better growing conditions for understory vegetation [89]. ...
Agroforestry provides essential ecosystem services; its structure and stability directly determine ecosystem function and service provision. Sustaining agroforestry ecosystem functions and services in the long term is necessary to meet the needs of people. This study conducted a literature search and statistical analysis based on WOS and CNKI literature databases. We reviewed 136 literature reports on studies of agroforestry ecosystem structure and stability. The landmark results are summarized in five aspects of agroforestry ecosystems: structure characteristics, structure optimization, structure design, stability research, and influence factors. On this basis, the key scientific issues that need to be solved are summarized, and their insights for improving the supply capacity of agroforestry ecosystem services under the rocky desertification control are discussed.
... Actually, it turned out that R. pseudoacacia had exerted highly competitive pressure on poplars throughout the 5 years. This can be explained by its crowns, which occupied the entire space and received full light from above and partly from the side (Rédei et al., 2018). It seems as if R. pseudoacacia took advantage of the rather narrow crowned poplar genotypes and was able to find the required space that they need for optimal growth (Nicolescu et al., 2020). ...
Short rotation coppice plays an important role for biomass production. Mixing fast‐growing tree species in short rotation coppices may lead to overyielding if the species have complementarity traits. The goal of this study is to analyze biomass yield of eight different poplar hybrids and black locust in mixed short rotation coppice after a rotation of 5 years. Pure and mixed stands were established at two sites of contrasting fertility as a low‐input system. After collecting a sample of trees for the data set, we fitted allometric equations to estimate the overall biomass of the stands. All poplar genotypes showed lower performance in mixtures with black locust, whereas the latter profited from the mixture. In contrast to our expectations, poplars had no advantages from black locust's nitrogen enrichment of the soil. Instead, the dominance and competitiveness of black locust drove to poorer performance of all eight poplar genotypes across both sites.
Mixing fast‐growing tree species in short rotation coppices may lead to overyielding if the species have complementarity traits. The goal of this study is to analyze biomass yield of eight different poplar hybrids and black locust in mixed short rotation coppice after a rotation of 5 years. While black locusts profited from mixed cropping, poplars had no advantaged performance. The dominance and competitiveness of black locust drove to poorer performance of all eight poplar genotypes.
There is an increasing trend in forest production towards planting rapid-growing trees as attractive, environmentally friendly energy sources. This study aimed to establish an alternative to the traditional propagation of a number of selections of Robinia pseudoacacia L. by developing an in vitro culture protocol. This study’s topic is of great importance, and it reflects an ongoing concern at the University of Oradea’s Faculty of Environmental Protection’s sustainable research program. The explants from four forms (called S1, S2, S3, and S4), selected for their phenotypic characteristics, were inoculated on four culture media (Murashige–Skoog (MS), Anderson, Chée–Pool, and Driver and Kuniyuki Woody (DKW)) with the same phytohormonal balance. DKW medium proved to be the better support of morphogenic activity, and it was further tested under different phytohormonal balances. Different results were observed depending on the hormone content in the DKW environment. In the presence of 0.5 mg/L benzylaminopurine (BAP) and 0.04 mg/L aminoisobutyric acid (AIB), 91.5% of the explants developed an average of 4.45 ± 0.18 shoots, whereas the average upper shoot height (3.82 cm) was recorded on DKW medium with 0.5 mg/L BAP and 0.04 mg/L α-naphthaleneacetic acid (NAA). Auxin, 0.05 mg/L AIB, promoted root production (5.27 ± 0.15 roots/explant), while 0.1 mg/L NAA promoted root length. In conclusion, the S4 selection produced the greatest outcomes of all environmental variables in terms of both the number of shoots and their heights.
Only 1.82% of the Czech forests are covered by the introduced (exotic, non-native) tree species, they represent only a very minor part of the forest area in the Czech Republic. Despite this fact under certain circumstances and locally, they can play an important role in the forest restoration of declined forests. The main non-native tree species used in the Czech Republic are: black locust ( Robinia pseudoacacia L.), Douglas-fir ( Pseudotsuga menziesii [Mirbel] Franco), grand fir ( Abies grandis [Douglas ex D. Don] Lindl.), black walnut ( Juglans nigra L.), northern red oak ( Quercus rubra L.), and blue spruce ( Picea pungens Engelm.). Other tree species are cultivated on very small areas, despite their much larger potential. The aim of the presented review paper is to summarize information on the introduced tree species, available especially from national sources, and give comprehensive information concerning the potential and risk of their use in the conditions of the Czech Republic. The authors mention also other tree species eligible for silviculture under current as well as future climatic circumstances. The current area and silvicultural potential in the climate changing conditions are analysed and summarized.
Allometric relationships between crown width (CW) and stem diameter at breast height (DBH) contribute in understanding forest dynamics and estimating forest biomass and carbon stocks. Nevertheless, the response of tree crown allometry to gap management and climate interactions remain unclear. We used 934 paired CW and DBH of Robinia pseudoacacia trees from 38 man-made gap forest sites (GPFs) of different sizes and 40 unmanaged forest sites (UMFs) in three counties with different climatic conditions in the Loess Plateau to (1) evaluate potential deviations in CW estimation from existing crown allometry models for R. pseudoacacia; (2) compare the predictive ability of nine common theoretical functions for crown allometry; (3) analyze scaling exponents variations of crown allometry, and test their fit to theoretical predictions; and (4) examine the influence of stand-level and climatic variables on crown allometric relationships. The existing CW-DBH equations provided better fit for GPFs than for UMFs, although substantial deviations were observed. The power function outperformed other theoretical forms for crown allometry in both GPFs and UMFs. The scaling exponents of the allometric relationships were lower in UMFs than in GPFs, which was closer to the metabolic-scaling theory predictions. Distance-independent competition considering average DBH accounted for major variations in crown allometric relationships in both gap-managed and unmanaged forests. Variations in scaling exponents in GPFs were also explained by diffuse light availability and climatic (annual precipitation and wind speed) variables. Our results highlight the significant role of climatic variables in affecting crown allometric relationships in forest gaps. These results have implications for developing vegetation models and long-term forest management in the context of climate change.
By using two thinning intensity regimes on a dense 16-year-old black locust (Robinia pseudoacacia L.) stand, two silvopastures were created: a medium density silvopasture (MDS) with 60% mean crown cover and a low density silvopasture (LDS) with 30% mean crown cover. An unthinned section of the stand with 90% mean crown cover was used as control (high density silvopasture: HDS). We measured the diameter at breast height (DBH) and tree height of black locust trees, in all three silvopastures, in 2011 (year of thinning), 2012 and 2013. In addition, we determined the forage production (in 2012 and 2013) and nutritive value (in 2013) of herbaceous vegetation and black locust shoots in the understory. The mean DBH for HDS, MDS and LDS increased from 7.6, 9.5 and 10.9 cm in 2011 to 8.6, 10.7 and 12.1 cm in 2013, respectively. The mean tree height also increased in the same period from 7.9, 9.1 and 9.8 m to 8.9, 10.1 and 10.6 m, for HDS, MDS and LDS, respectively. The mean herbage production was similar (P > 0.05) among silvopastures, although there was a tendency to be higher in the MDS and LDS (1866 and 1957 kg DM/ha, respectively) compared to HDS (1682 kg DM/ha). Additionally, browse from black locust shoots increased forage in MDS and LDS by 751 and 1201 kg DM/ha, respectively. Black locust browse had a higher overall nutritive value than herbage across silvopastures and months. In terms of crude protein, the content in black locust browse was on average twice as high, across sites and years, as that of herbage (239.4 vs. 104.1 g/kg DM; P < 0.05). While neutral detergent fiber and acid detergent fiber content of black locust browse were consistently lower (P < 0.05) than that of herbage, acid detergent lignin content of browse material was higher (P < 0.05) than that of herbage and averaged 94.7 and 75.4 g/kg DM, respectively. Overall, our results show that thinning resulted in higher values for both DBH and height of trees and increased forage in the understory by supplementing herbage with browse of high nutritive value.
