Thinning of Korean pine (Pinus koraiensis Sieb. et Zucc.) is used to facilitate timber and cone production. The present study in Northeast China investigated the effects of thinning intensity on individual tree growth...Thinning of Korean pine (Pinus koraiensis Sieb. et Zucc.) is used to facilitate timber and cone production. The present study in Northeast China investigated the effects of thinning intensity on individual tree growth, temporal variation in cone yield, and seed quality in Korean pine plantation. In 2005, five thinning intensity levels (none, extreme, heavy, moderate and light) were set in 15 permanent plots in a 32-year-old Korean pine plantation at Mengjiagang Forest Farm, Jiamusi City, Heilongjiang Province. We recorded tree growth and seed cone production from 2013 to 2016, i.e., from 8 to 11 years after thinning. Except for height growth, thinning increased tree growth (diameter at breast height and crown size) and improved cone yield. The extreme thinning treatment (to 300 trees per hectare) resulted in the largest tree diameter, tree volume, crown size and 4-year cone production per tree. The highest cone yield per tree in the mast year (2014) was observed when stands were thinned to 500 trees per hectare (heavy thinning). Although the best cone and seed quality and the largest cone and seed mass per tree were recorded in the heavily thinned stand, no significant differences were found between heavy and moderate thinning stands (750 trees per hectare). At the stand level, the moderately thinned stand had the highest basal area, stock volume and seed cone production per stand. Our results suggest that thinning to 750 trees per hectare will improve timber and cone productivity in 40-year-old P. koraiensis stands.展开更多
The origin of a seed strongly impacts its traits, and both origin and seed traits influence seed germination and seedling development. However, in many instances, this effect on the seedling does not persist into adul...The origin of a seed strongly impacts its traits, and both origin and seed traits influence seed germination and seedling development. However, in many instances, this effect on the seedling does not persist into adulthood, and little is known about how seed traits and original environment affect seedling/tree growth over time. In this study, seed size, seed mass, seedling/tree growth and origins were collected and determined for 23 provenances of Quercus acutissima from across China. Origin variables correlated well with seed size and seed mass. In stepwise multiple regressions, a longitudinal aridity index explained 49.2-68.7% of the total variation in seed size and mass, while only seed width was correlated with seedling/tree height (H) and diameter at the ground (D) from seed traits and origins. The total variance in H and D explained by the models decreased over time, for example, the R <sup>2</sup> value of the models for H declined from 0.477 in the first year to 0.224 in the fourth year; no models was significant in the fifth year. These results indicate that seed size, regulated by the longitudinal aridity index strongly impacted seedling and tree growth, but the strength of the influence decreased over time, and disappeared after 4 years.展开更多
The influence of the foliage boron（B）-spaying concentration on the yield and fatty acid composition of tree peony（Paeonia ostii ＇Feng Dan＇） was explored in the experiment of 2014-2015. In this research, a statis...The influence of the foliage boron（B）-spaying concentration on the yield and fatty acid composition of tree peony（Paeonia ostii ＇Feng Dan＇） was explored in the experiment of 2014-2015. In this research, a statistically significant correlation was found between the mass concentration of foliage boron-spraying and tree peony seed yield. Maximum yield increment of tree peony seeds was obtained when the boron-spraying concentration was 4 g/L. The composition of fatty acid was analyzed by gas chromatography-mass spectrometry（GC-MS）, and the main components of the fatty acid composition were quantified by internal standard method. The increase in the oil extraction rate after foliage boron-spraying nutrition of different concentration was significant and ranged between 0.04% and 11.43%. Seed oil production and oil extraction rate were also increased due to the increase of seed yields. Furthermore, foliage boron-spraying had a significant effect on the content of linolenic acid and linoleic acid in seed oil.展开更多
Investigations were made to determine the nature and extent of variations present for 10 morphological characters of cone,seed and seedlings of 17 plus trees（PTs）of Pinus kesiya growing in eastern Himalayas（Meghala...Investigations were made to determine the nature and extent of variations present for 10 morphological characters of cone,seed and seedlings of 17 plus trees（PTs）of Pinus kesiya growing in eastern Himalayas（Meghalaya state） of India.The significant variations has been observed in cone weight,cone length,cone diameter,seed length,seed diameter,seed weight,number of seeds per cone,seed germination,seedling height and seedling collar diameter among different PTs of the species.Significant positive correlation（p ／ 0.01） between seed weight,cone length and cone diameter showed that seed weight in P.kesiya depend more on the cone size.Seed germination is found positively correlated（p ／ 0.01） with seed weight,seed diameter,cone size and number of seeds per cone in the study.Among geographical factors,latitude and altitude are found positively correlated（p ／ 0.05） with cone weight and seed diameter,respectively.The genetic parameters for seed,cone and seedlings of PTs of P.kesiya also showed a wide range of variability in terms of variance,coefficient of variability,broad sense heritability,genetic advance and genetic gain.Seed weight,seeds per cone and seedling diameter showed high heritability values（[75） coupled with maximum genetic gain.Traits with such values indicate the presence of good amount of heritable additive components and are under strong genetic control.The findings of the study revealed that PTs expressed both phenotypic and genotypic differences in the seed,cone and seedling characters,which may be attributed to the differences in genetic makeup of various PTs and environmental factors i.e.genotypic and environmental interaction.The presence of high variability in P.kesiya PTs for different characters provide further opportunities to improve the population in subsequent generations so as to establish this species as an important timber tree to be grown on less fertile and degraded soils in its distributional ranges.展开更多
The non-edible camphor tree seed oil was extracted and catalyzed by immobilized lipase for biodiesel production. The oil yield from camphor tree seeds reached 35.2% of seed weight by twice microwave-assisted extractio...The non-edible camphor tree seed oil was extracted and catalyzed by immobilized lipase for biodiesel production. The oil yield from camphor tree seeds reached 35.2% of seed weight by twice microwave-assisted extractions. Gas chromatography showed that free fatty acid content in camphor tree seed oil was 1.88%, and the main fatty acids were capric acid(53.4%) and lauric acid(38.7%). With immobilized lipase Candida sp. 99–125as catalyst, several important factors for reaction conditions were examined through orthogonal experiments.The optimum conditions were obtained: water content and enzyme loading were both 15% with a molar ratio of 1:3.5(oil/ethanol), and the process of alcoholysis was in nine steps at 40 °C for 24 h, with agitation at170 r·min-1. As a result, the medium-chain biodiesel yield was 93.5%. The immobilized lipase was stable when it was used repeatedly for 210 h.展开更多
Ponderosa pine (Pinus ponderosa Laws) has been planted widely in the Great Plains for wind breaks. A 1968 study recommended using material from south-central South Dakota and north-central Nebraska. A second test to f...Ponderosa pine (Pinus ponderosa Laws) has been planted widely in the Great Plains for wind breaks. A 1968 study recommended using material from south-central South Dakota and north-central Nebraska. A second test to further delineate seed sources (families) from numerous collection sites in this region was established in 1986. This paper reports results for survival, height, diameter, and D2H (diameter squared X height) measurements at 15 years. Results identify a wide range of suitable families within the region. A majority of the tested sources performed well, thus verifying the original recommendations.展开更多
Melaleuca quinquenervia is an Australian tree that has successfully invaded many habitats in Florida. It maintains an aerial seed bank in serotinous capsular fruits held in the tree canopies. These fruits open gradual...Melaleuca quinquenervia is an Australian tree that has successfully invaded many habitats in Florida. It maintains an aerial seed bank in serotinous capsular fruits held in the tree canopies. These fruits open gradually and shed seeds that fall (rain) throughout the year. Comparative attributes (quantities and qualities) of these fallen seeds from different habitats and tree size categories are unknown. We documented these attributes of fallen M. quinquenervia seeds for 12 months among three tree size categories from each of the two hydrologically delineated habitat types. Quantities (8961 seeds m2·mo-1) and the viability (8.8%) and germinability (8.4%) of fallen melaleuca seeds in the occasionally inundated habitat were significantly higher (P = 0.05) than the quantities (6716 seeds m2·mo-1), and viability (5.6%) and germinability (5.3%) of melaleuca seeds in the permanently inundated habitat. Although relatively more seeds rained from larger trees, higher quality seeds were rained from the trees of smaller dimensions. Smaller trees typically inhabit at the edges of melaleuca stands and hence they may increase the potential for further spread of seeds into the adjacent areas.展开更多
The predicated changes in precipitation and temperature associated with the continued elevation of atmospheric CO2 concentration will trigger the northward shift of the Climate Envelopes for 130 North America tree spe...The predicated changes in precipitation and temperature associated with the continued elevation of atmospheric CO2 concentration will trigger the northward shift of the Climate Envelopes for 130 North America tree species by as much as 10 degrees. However, climate envelope models do not take into account changes in other factors that may also influence the survival and growth of plants at the predicted new locations, such as photoperiod and nutrient regimes. This study investigated how photoperiod and nitrogen supply would affect the ecophysiological traits of black spruce (Picea mariana (Mill) B. S. P.) that are critical for survival and growth at new locations predicted by climate envelope models. We exposed black spruce seedlings to the photoperiod regime at the seed origin (PS) and that 10° north of the seed origin (PNM) as predicted by climate envelope models under the current and doubled atmospheric CO2 concentration and different levels of N supply (30 vs. 300 μmol·mol-1 N). We found that the PNM and the 30 μmol·mol-1 N supply both had negative impact on the development of seedling cold hardiness in the fall, and led to earlier burst of the terminal bud and greater rate of mortality in the following growing season. While the PNM stimulated seedling growth in the first growing season, the effect was not sustained in the second growing season. Our results suggest that the photoperiod regimes and poor nutrient conditions at higher latitudes will likely constrain the scope of the northward migration or seed transfer of black spruce.展开更多
Pumpkin seed (Cucurbita pepo L.) is a nutritionally valuable food and a significant source of income globally. Pumpkin seeds are rich in oil, protein, unsaturated fatty acids and tocopherols, which are associated with...Pumpkin seed (Cucurbita pepo L.) is a nutritionally valuable food and a significant source of income globally. Pumpkin seeds are rich in oil, protein, unsaturated fatty acids and tocopherols, which are associated with improved human health. Understanding the genetic diversity among pumpkin accessions varying in seed nutrition traits is necessary for designing sound breeding strategies for developing superior cultivars. In the current study, 26 simple sequence repeats (SSR) markers were used to assess genetic relatedness among 29 C. pepo accessions varying in seed oil, seed protein, seed-coat phenotype, seed size and fatty acid composition. The SSR markers revealed 102 alleles averaging 3.92 alleles per loci and mean polymorphic information content (PIC) of 0.44. Eleven of the markers had a PIC of ≥0.5. Ward dendrogram and principle component analysis based on seed traits grouped the genotypes into two major clusters corresponding to subspecies pepo and texana, with all the reduced-hull accessions grouping within the former. Collectively, this data suggests wide phenotypic (seed traits) and genotypic variation within C. pepo that may be exploited to develop superior reduced-hull cultivars.展开更多
The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in...The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in two post-logging plots of Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and another exploited in 2021. In each study plot, 40 samples were collected per soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth). The species diversity and abundance of the soil seed bank were estimated after soil samples were brought to germination. The results demonstrated that 347 seedlings belonging to 37 species in the plot exploited in 2008 and 418 seedlings belonging to 27 species in that exploited in 2021 germinated during 20 weeks of monitoring. The total densities of the seedlings identified were respectively 1446 seedlings/m<sup>2</sup> and 1742 seedlings/m<sup>2</sup>. The plot exploited in 2021 presented a higher proportion of herbaceous species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer species were recorded in the plot exploited in 2008. These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to 20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer demonstrated important proportions in woody species (9%), these are in particular Rubiaceae sp.4 and Nauclea diderrichii. While that exploited in 2021, presented 19% of woody species, namely the species of Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species recorded with densities of 108 seedlings/m<sup>2</sup> and 4 seedlings/m<sup>2</sup>, respectively in the plot exploited in 2008 and that exploited in 2021. Commercial tree species are poorly represented in the soil seed bank. Consequently, the study suggests that to improve the natural regeneration of the commercial species, silvicultural interventions based on planting techniques in the exploited plots should be more effective in order to sustainably manage these production forests.展开更多
基金supported by National Key R&D Program of China(2017YFD0600601)
文摘Thinning of Korean pine (Pinus koraiensis Sieb. et Zucc.) is used to facilitate timber and cone production. The present study in Northeast China investigated the effects of thinning intensity on individual tree growth, temporal variation in cone yield, and seed quality in Korean pine plantation. In 2005, five thinning intensity levels (none, extreme, heavy, moderate and light) were set in 15 permanent plots in a 32-year-old Korean pine plantation at Mengjiagang Forest Farm, Jiamusi City, Heilongjiang Province. We recorded tree growth and seed cone production from 2013 to 2016, i.e., from 8 to 11 years after thinning. Except for height growth, thinning increased tree growth (diameter at breast height and crown size) and improved cone yield. The extreme thinning treatment (to 300 trees per hectare) resulted in the largest tree diameter, tree volume, crown size and 4-year cone production per tree. The highest cone yield per tree in the mast year (2014) was observed when stands were thinned to 500 trees per hectare (heavy thinning). Although the best cone and seed quality and the largest cone and seed mass per tree were recorded in the heavily thinned stand, no significant differences were found between heavy and moderate thinning stands (750 trees per hectare). At the stand level, the moderately thinned stand had the highest basal area, stock volume and seed cone production per stand. Our results suggest that thinning to 750 trees per hectare will improve timber and cone productivity in 40-year-old P. koraiensis stands.
基金supported by the National Natural Science Foundation of China(No.31570583)the Lecture and Study Program for Outstanding Scholars from Home and Abroad(No.CAFYBB2011007)
文摘The origin of a seed strongly impacts its traits, and both origin and seed traits influence seed germination and seedling development. However, in many instances, this effect on the seedling does not persist into adulthood, and little is known about how seed traits and original environment affect seedling/tree growth over time. In this study, seed size, seed mass, seedling/tree growth and origins were collected and determined for 23 provenances of Quercus acutissima from across China. Origin variables correlated well with seed size and seed mass. In stepwise multiple regressions, a longitudinal aridity index explained 49.2-68.7% of the total variation in seed size and mass, while only seed width was correlated with seedling/tree height (H) and diameter at the ground (D) from seed traits and origins. The total variance in H and D explained by the models decreased over time, for example, the R <sup>2</sup> value of the models for H declined from 0.477 in the first year to 0.224 in the fourth year; no models was significant in the fifth year. These results indicate that seed size, regulated by the longitudinal aridity index strongly impacted seedling and tree growth, but the strength of the influence decreased over time, and disappeared after 4 years.
基金Supported by the Chinese Special Fund for Forest Scientific Research in the Public Welfare Program(201404701)
文摘The influence of the foliage boron（B）-spaying concentration on the yield and fatty acid composition of tree peony（Paeonia ostii ＇Feng Dan＇） was explored in the experiment of 2014-2015. In this research, a statistically significant correlation was found between the mass concentration of foliage boron-spraying and tree peony seed yield. Maximum yield increment of tree peony seeds was obtained when the boron-spraying concentration was 4 g/L. The composition of fatty acid was analyzed by gas chromatography-mass spectrometry（GC-MS）, and the main components of the fatty acid composition were quantified by internal standard method. The increase in the oil extraction rate after foliage boron-spraying nutrition of different concentration was significant and ranged between 0.04% and 11.43%. Seed oil production and oil extraction rate were also increased due to the increase of seed yields. Furthermore, foliage boron-spraying had a significant effect on the content of linolenic acid and linoleic acid in seed oil.
基金funded by Indian Council of Forestry and Education,Dehradun
文摘Investigations were made to determine the nature and extent of variations present for 10 morphological characters of cone,seed and seedlings of 17 plus trees（PTs）of Pinus kesiya growing in eastern Himalayas（Meghalaya state） of India.The significant variations has been observed in cone weight,cone length,cone diameter,seed length,seed diameter,seed weight,number of seeds per cone,seed germination,seedling height and seedling collar diameter among different PTs of the species.Significant positive correlation（p ／ 0.01） between seed weight,cone length and cone diameter showed that seed weight in P.kesiya depend more on the cone size.Seed germination is found positively correlated（p ／ 0.01） with seed weight,seed diameter,cone size and number of seeds per cone in the study.Among geographical factors,latitude and altitude are found positively correlated（p ／ 0.05） with cone weight and seed diameter,respectively.The genetic parameters for seed,cone and seedlings of PTs of P.kesiya also showed a wide range of variability in terms of variance,coefficient of variability,broad sense heritability,genetic advance and genetic gain.Seed weight,seeds per cone and seedling diameter showed high heritability values（[75） coupled with maximum genetic gain.Traits with such values indicate the presence of good amount of heritable additive components and are under strong genetic control.The findings of the study revealed that PTs expressed both phenotypic and genotypic differences in the seed,cone and seedling characters,which may be attributed to the differences in genetic makeup of various PTs and environmental factors i.e.genotypic and environmental interaction.The presence of high variability in P.kesiya PTs for different characters provide further opportunities to improve the population in subsequent generations so as to establish this species as an important timber tree to be grown on less fertile and degraded soils in its distributional ranges.
基金Supported by Key Projects in the National Science & Technology Pillar Program during the 12th Five-year Plan Period(2011BAD22B04)the National Basic Research Program of China(973 program)(2011CB710800,2011CB200905,2009CB724703)+2 种基金the National Natural Science Foundation of China(21076017)the National High-Tech R & D Program of China(863 Program)(2012AA021404,2012AA021402)the Fundamental Research Funds for the Central Universities(ZY1331)
文摘The non-edible camphor tree seed oil was extracted and catalyzed by immobilized lipase for biodiesel production. The oil yield from camphor tree seeds reached 35.2% of seed weight by twice microwave-assisted extractions. Gas chromatography showed that free fatty acid content in camphor tree seed oil was 1.88%, and the main fatty acids were capric acid(53.4%) and lauric acid(38.7%). With immobilized lipase Candida sp. 99–125as catalyst, several important factors for reaction conditions were examined through orthogonal experiments.The optimum conditions were obtained: water content and enzyme loading were both 15% with a molar ratio of 1:3.5(oil/ethanol), and the process of alcoholysis was in nine steps at 40 °C for 24 h, with agitation at170 r·min-1. As a result, the medium-chain biodiesel yield was 93.5%. The immobilized lipase was stable when it was used repeatedly for 210 h.
文摘Ponderosa pine (Pinus ponderosa Laws) has been planted widely in the Great Plains for wind breaks. A 1968 study recommended using material from south-central South Dakota and north-central Nebraska. A second test to further delineate seed sources (families) from numerous collection sites in this region was established in 1986. This paper reports results for survival, height, diameter, and D2H (diameter squared X height) measurements at 15 years. Results identify a wide range of suitable families within the region. A majority of the tested sources performed well, thus verifying the original recommendations.
文摘Melaleuca quinquenervia is an Australian tree that has successfully invaded many habitats in Florida. It maintains an aerial seed bank in serotinous capsular fruits held in the tree canopies. These fruits open gradually and shed seeds that fall (rain) throughout the year. Comparative attributes (quantities and qualities) of these fallen seeds from different habitats and tree size categories are unknown. We documented these attributes of fallen M. quinquenervia seeds for 12 months among three tree size categories from each of the two hydrologically delineated habitat types. Quantities (8961 seeds m2·mo-1) and the viability (8.8%) and germinability (8.4%) of fallen melaleuca seeds in the occasionally inundated habitat were significantly higher (P = 0.05) than the quantities (6716 seeds m2·mo-1), and viability (5.6%) and germinability (5.3%) of melaleuca seeds in the permanently inundated habitat. Although relatively more seeds rained from larger trees, higher quality seeds were rained from the trees of smaller dimensions. Smaller trees typically inhabit at the edges of melaleuca stands and hence they may increase the potential for further spread of seeds into the adjacent areas.
文摘The predicated changes in precipitation and temperature associated with the continued elevation of atmospheric CO2 concentration will trigger the northward shift of the Climate Envelopes for 130 North America tree species by as much as 10 degrees. However, climate envelope models do not take into account changes in other factors that may also influence the survival and growth of plants at the predicted new locations, such as photoperiod and nutrient regimes. This study investigated how photoperiod and nitrogen supply would affect the ecophysiological traits of black spruce (Picea mariana (Mill) B. S. P.) that are critical for survival and growth at new locations predicted by climate envelope models. We exposed black spruce seedlings to the photoperiod regime at the seed origin (PS) and that 10° north of the seed origin (PNM) as predicted by climate envelope models under the current and doubled atmospheric CO2 concentration and different levels of N supply (30 vs. 300 μmol·mol-1 N). We found that the PNM and the 30 μmol·mol-1 N supply both had negative impact on the development of seedling cold hardiness in the fall, and led to earlier burst of the terminal bud and greater rate of mortality in the following growing season. While the PNM stimulated seedling growth in the first growing season, the effect was not sustained in the second growing season. Our results suggest that the photoperiod regimes and poor nutrient conditions at higher latitudes will likely constrain the scope of the northward migration or seed transfer of black spruce.
文摘Pumpkin seed (Cucurbita pepo L.) is a nutritionally valuable food and a significant source of income globally. Pumpkin seeds are rich in oil, protein, unsaturated fatty acids and tocopherols, which are associated with improved human health. Understanding the genetic diversity among pumpkin accessions varying in seed nutrition traits is necessary for designing sound breeding strategies for developing superior cultivars. In the current study, 26 simple sequence repeats (SSR) markers were used to assess genetic relatedness among 29 C. pepo accessions varying in seed oil, seed protein, seed-coat phenotype, seed size and fatty acid composition. The SSR markers revealed 102 alleles averaging 3.92 alleles per loci and mean polymorphic information content (PIC) of 0.44. Eleven of the markers had a PIC of ≥0.5. Ward dendrogram and principle component analysis based on seed traits grouped the genotypes into two major clusters corresponding to subspecies pepo and texana, with all the reduced-hull accessions grouping within the former. Collectively, this data suggests wide phenotypic (seed traits) and genotypic variation within C. pepo that may be exploited to develop superior reduced-hull cultivars.
文摘The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in two post-logging plots of Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and another exploited in 2021. In each study plot, 40 samples were collected per soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth). The species diversity and abundance of the soil seed bank were estimated after soil samples were brought to germination. The results demonstrated that 347 seedlings belonging to 37 species in the plot exploited in 2008 and 418 seedlings belonging to 27 species in that exploited in 2021 germinated during 20 weeks of monitoring. The total densities of the seedlings identified were respectively 1446 seedlings/m<sup>2</sup> and 1742 seedlings/m<sup>2</sup>. The plot exploited in 2021 presented a higher proportion of herbaceous species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer species were recorded in the plot exploited in 2008. These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to 20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer demonstrated important proportions in woody species (9%), these are in particular Rubiaceae sp.4 and Nauclea diderrichii. While that exploited in 2021, presented 19% of woody species, namely the species of Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species recorded with densities of 108 seedlings/m<sup>2</sup> and 4 seedlings/m<sup>2</sup>, respectively in the plot exploited in 2008 and that exploited in 2021. Commercial tree species are poorly represented in the soil seed bank. Consequently, the study suggests that to improve the natural regeneration of the commercial species, silvicultural interventions based on planting techniques in the exploited plots should be more effective in order to sustainably manage these production forests.
