Stem taper function for sweet chestnut (Castanea sativa Mill.) coppice stands in northwest Spain

? Context

Despite the economic importance of Castanea sativa Mill. in northwest Spain, studies of its growth and yield are practically non-existent.

? Aims

A compatible system formed by a taper function, a total volume equation, and a merchantable volume equation was developed for chestnut (C. sativa Mill.) coppice stands in northwest Spain.

? Methods

Data from 203 destructively sampled trees were used for the adjustment. Outliers were removed with a non-parametric local adjustment, providing a final data set of measurements taken from 3,188 sections which was used to test five taper models (compatible and non-compatible). A second-order continuous autoregressive error structure was used to model the error term and account for autocorrelation. Presence of multicollinearity was evaluated with the condition number. Comparison of the models was carried out using overall goodness-of-fit statistics and graphical analysis.

? Results

Results show that the models developed by Fang et al. in For Sci 46: 1–12, 2000 and Kozak in For Chron 80, N 4: 507–515, 2004 were superior to other equations in predicting diameter for chestnut coppice stands.

? Conclusion

The compatible volume system developed by Fang et al. in For Sci 46: 1–12, 2000 was finally selected as it provided the best compromise between describing stem profile and also estimating merchantable height, merchantable volume, and total volume and therefore provides the first specific tool for more effective management of chestnut coppice stands.     

Grading and mechanical characterization of small-diameter round chestnut (Castanea sativa Mill.) timber from thinning operations

ABSTRACT

In forestry, thinning operations result in the extraction of young trees with small dimensions. The evaluation of the potential end use of these small-diameter logs (currently mainly used as poles or fence posts) for added-value products such as structural timber is of considerable economic and industrial interests. In the present work, 216 pieces of small-diameter logs of chestnut timber obtained from thinning operations were evaluated in order to determine their mechanical properties and assess various visual or non-destructive grading systems. The two visual standards evaluated (EN 1927 and DIN 4074) were ineffective in grading according to mechanical properties. On the other hand, a grading system based on a non-destructive measurement (acoustic wave velocity) resulted in better classification by structural quality. The characteristic values of the small-diameter round chestnut timber, determined according to the standards EN 384 and EN 338, achieved similar values as standard rectangular sawn timber with respect to modulus of elasticity and density, and higher values for bending strength.     

Deformation induced by ethanol substitution in normal and tension wood of chestnut (Castanea sativa Mill.) and simarouba (Simarouba amara Aubl.)

Wood deformation in the longitudinal and tangential directions induced by ethanol substitution and oven-drying was measured in normal wood (NW) and tension wood (TW) of chestnut (Castanea sativa Mill.) (TW with G-fibres) and simarouba (Simarouba amara Aubl.) (TW without G-fibres). The results show that with increased concentration of ethanol solution TW tends to contract, regardless of the presence or absence of G-fibres. In contrast, both NW and opposite wood expand at different rates in the longitudinal direction. These results are discussed and explained by the role of stress state at cell wall level.     

The effects of propagation environment on the rooting of leafy cuttings of ash (Fraxinus excelsior L.), sycamore (Acer pseudoplatanus L.), and sweet chestnut (Castanea sativa Mill.)

The effect of propagation environment on the rooting of field collected leafy cuttings of ash (Fraxinus excelsior, sycamore (Acer pseudoplatanus) and sweet chestnut (Castanea sativa) was investigated in two experiments. In the first experiment, rooting of all three species in mist enclosed inside a polythene tent was greater than 50%, while rooting of ash cuttings was reduced from 63% in enclosed mist to only 16% in open mist. Rooting in open mist, enclosed mist, and contact polythene was studied in a second experiment. Sycamore cuttings rooted equally well in the two mist systems with an average rooting of 78%. In contrast cuttings of both ash and sweet chestnut rooted most under the enclosed mist system, at 64 and 46% respectively. Rooting of ash cuttings was again depressed in the open mist system where less than 30% of cuttings rooted. This reduction was related to an increase in the percentage of cuttings which remained alive without rooting, while showing proliferation of callus at the cutting base. The percentage of sweet chestnut cuttings which callused without rooting was also much greater in the open mist system than in enclosed mist or contact polythene.     

Synergistic effect of drought and chestnut blight (Cryphonectria parasitica) on growth decline of European chestnut (Castanea sativa)

The chestnut blight fungus [Cryphonectria parasitica (Murill) Barr] has threatened European chestnut stands (Castanea sativa Mill.) in the 20th century, but infected trees recovered because of the appearance of hypovirulent strains. However, within a dry inner Alpine valley (Italy), blight‐infected C. sativa showing various degrees of crown dieback and dead trees were found. We conducted a dendroecological analysis to retrospectively evaluate a possible synergistic effect of blight infection in the early 1970s and climate stress on the growth decline of C. sativa. In the Eisack Valley (Italy), where annual precipitation is <700 mm, increment cores were taken from blight‐infected C. sativa (n = 103) showing different levels of decline symptoms, i.e. extent of crown dieback (healthy, moderate, severe), and from dead trees. Ring width and basal area increment (BAI) chronologies were developed based on dendroecological methods. Growth–climate relationships were explored using response function analysis and Pearson correlation coefficients. Major findings of our study were: (i) C. sativa growth is limited by low precipitation from December to February and high temperatures in June, (ii) BAI of all vitality classes except healthy trees shows a decreasing trend since 1980; and (iii) a severe drought in 1996 accelerated growth decline and caused death of infected C. sativa individuals. Because of the strong influence of climate on radial tree growth within the study area and observed divergent growth trends in selected vitality classes after infestation by hypovirulent C. parasitica strains in the early 1970s, we conclude that although blight infection is a prerequisite for observed growth declines, soil water availability in the years of drought strongly affects susceptibility to tree death.     

Detection,description, and technological properties of colour aberration in wood of standards and shoots from a chestnut (Castanea sativa Mill.) coppice stand

European Journal of Forest Research - Sweet chestnut forests occupy an important role in Italy and Europe, its resilience is often affected by aggressive pathogen attack. In the last times some...     

Reinvigoration of mature chestnut (Castanea sativa) by repeated graftings and micropropagation

Gradual reinvigoration of adult chestnut (Castanea sativa M. cv. Montemarano) shoots was obtained by serial grafting onto juvenile rootstocks. The phenomenon was evaluated on the basis of percentage of primary nodes regenerating axillary shoots and length and number of shoots (> 10 mm) per primary node. In vitro growth of explants from serially grafted shoots was significantly lower than that of explants from seedlings at the end of the establishment phase. Only microshoots from seedlings and plants that had been serially grafted four times could be subcultured on proliferation medium. Repeated subculture on medium containing a low cytokinin concentration induced progressive reinvigoration of microshoots derived from plants that had been serially grafted four times. The number of axillary shoots per explant increased significantly after six subcultures. After 12 subcultures, microshoots from serially grafted plants showed an increase in stem elongation, rooting and plantlet survival. After in vitro stabilization, there was no difference in in vitro performance between microshoots derived from seedlings and serially grafted plants. Microshoots multiplied from serially grafted plants displayed only a transitory appearance of juvenile traits.     

MALDI-TOF, HPLC-ESI-TOF and 13C-NMR characterization of chestnut (Castanea sativa) shell tannins for wood adhesives

MALDI-TOF, HPLC-ESI-TOF and 13C-NMR techniques were used to analyse the structure of non-purified aqueous chestnut shell tannin extracts. In addition, the influence of the extraction agent (water or aqueous solutions of Na₂SO₃ and/or NaOH) on tannin structure was analysed by MALDI-TOF in order to select the extract with the best properties for wood adhesives. Using HPLC-ESI-TOF, catechin/epicatechin, gallocatechin/epigallocatechin, dicatechin structures, dicatechin structures without a hydroxyl group, galloyl-glucoses and ellagic acid were identified as the main monomeric components in the aqueous extract. 13C-NMR and MALDI-TOF spectra revealed that extracts are mostly composed of procyanidin and prodelphinidin structures although prorobinetidins might be also present. MALDI-TOF spectrometry was used to identify the extract oligomeric components. Extractions with Na₂SO₃ and/or NaOH produced changes in the predominant structures in the extracts and on the amount of sugar units linked to the flavonoid structures, which decreased in the presence of Na₂SO₃. Extract obtained using low Na₂SO₃ and NaOH concentrations (1.5 and 0.75 %, respectively) was selected as more suitable for wood adhesive preparation.     

Effect of management and spatial characteristics on plant species richness of Castanea sativa Mill. woodlots in the NW Iberian Peninsula

This paper analyzes the effect of the spatial characteristics and intensity of land use on vascular plant species richness in Castanea (Chestnut) woodlots of the northwestern Iberian Peninsula included in the category “9260 Castanea sativa woodland” (Annex I, DC 92/43 European Community). Digital maps were used to characterize 30 woodlots for which land use intensity was estimated and all plants found were inventoried. The results show that woodlot shape and land use intensity have a significant effect on vascular plant richness and indicator species number. However, an analysis of the interaction between woodlot characteristics and land use intensity suggests that the response of vascular plant species to land use intensity does not exhibit a uniform pattern and that it is modulated by the shape of the woodlots. We conclude that restricting the use of these types of woods to traditional practices must be determined in keeping with the specific characteristics of each woodlot, since the moderate management of Castanea sativa woodlots of the northwest Iberian Peninsula may continue to play an important role to maintaining plant species diversity in this area.     

Osmotic potential and gas exchange in healthy and diseased silver firs (Abies alba Mill.)1

The present study comprises comparative investigations of transpiration, photosynthesis and osmotic potential of various twigs of a healthy and a diseased fir. Possible causes for the registered differences are discussed.     

Canopy fuel characteristics and potential crown fire behavior in Aleppo pine (Pinus halepensis Mill.) forests

Canopy fuel characteristics that influence the initiation and spread of crown fires were measured in representative Aleppo pine (Pinus halepensis Mill.) stands in Greece. Vertical distribution profiles of canopy fuel load, canopy base height and canopy bulk density are presented. Aleppo pine canopy fuels are characterized by low canopy base height (3.0–6.5 m), while available canopy fuel load (0.96–1.80 kg/m²) and canopy bulk density (0.09–0.22 kg/m³) values are similar to other conifers worldwide. Crown fire behavior (probability of crown fire initiation, crown fire type, rate of spread, fireline intensity and flame length) in Aleppo pine stands with various understory fuel types was simulated with the most updated crown fire models. The probability of crown fire initiation was high even under moderate burning conditions, mainly due to the low canopy base height and the heavy surface fuel load. Passive crown fires resulted mostly in uneven aged stands, while even aged stands gave high intensity active crown fires. Assessment of canopy fuel characteristics and potential crown fire behavior can be useful in fuel management and fire suppression planning.     

Influence of alfalfa (Medicago sativa L.) intercropping and polyethylene mulching on early growth of walnut (Juglans spp.) in central Italy

Combined production of timber and forage species is considered to be a desirable land-use system to offset some of the current land management problems of Italy. This paper reports the early results of a study on intercropping young plants of walnut with alfalfa (Medicago sativa L.), with or without polyethylene mulching, in an experimental plantation in central Italy. Two genotypes of walnut were used:Juglans regia L. and the French hybrid NG23×RA. The seasonal changes of absolute and relative growth rates of walnut stem diameter and apical shoot length were investigated.During both growing seasons, alfalfa intercropping strongly decreased walnut growth, whereas polyethylene mulching promoted stem height and diameter growth. Stem growth of intercropped-and-mulched walnut was the same as that of sole walnut under clean cultivation management. The use of polyethylene mulching reduced or avoided the competitive effect of associated alfalfa on walnut growth. During both growing seasons, the intercropped-and-mulched walnut had higher relative growth rates than intercropped-unmulched walnut. The results show the effectiveness of polyethylene mulching in promoting early growth of walnut, even when intercropped with alfalfa during early stages of plantation establishment.     

Effectiveness of a detached‐leaf assay as a proxy for stem inoculations in backcrossed chestnut (Castanea) blight resistance breeding populations

A recently developed detached‐leaf blight resistance assay has generated interest because it could reduce the amount of time needed to evaluate backcrossed hybrid trees in the American chestnut blight resistance breeding programme. We evaluated the leaf inoculation technique on a sample of advanced progeny from the Indiana state chapter American Chestnut Foundation breeding programme, along with susceptible American chestnut (Castanea dentata), the recurrent parent, and resistant Chinese chestnut (Castanea mollissima), the donor parent for blight resistance. In experiments over 2 years using two pathogen isolates, we found no biologically meaningful relationship between leaf lesion size and the size (length and width) or severity (1–5 canker severity rating) of stem cankers on 5‐year‐old trees. Chinese chestnuts did develop significantly smaller leaf lesions than American or backcrossed chestnuts. We conclude that while the detached‐leaf assay may have utility in some chestnut breeding applications, it is not a suitable proxy for the established practice of stem inoculations.     

Carbon fractions as indicators of organic matter dynamics in chestnut orchards under different soil management practices

Several studies have emphasized the negative impact of the conventional soil management (CT) system on productivity and sustainability of chestnut orchards (Castanea sativa Mill.) when compared to no-tillage with grass cover (NT). However, scarce information is available regarding the effects of these soil management systems on soil organic matter (SOM) dynamics and soil quality. SOM or soil organic carbon is a key component of soil quality and has different fractions with different lability, namely, organic C (POC), active C (AC) and hot-water extractable carbon (HWC). These are considered as indicators of changes in management-induced soil quality. Thus, a study was carried out to evaluate the effects of NT and CT systems applied in the chestnut orchards on: (i) total amount of soil organic C (TOC), including C from both organic and mineral layers; (ii) soil organic C concentration of mineral horizons (OC); (iii) labile soil organic fractions (POC, AC, HWC); (iv) and soil mineral-associated C. The study was developed in two 30-year old chestnut orchards located in Northeast Portugal, that were kept under different soil management systems (NT or CT) during the preceding 17 years. Soil samples were taken at 0–10 and 10–20 cm soil depth. No significant differences in OC concentration were observed between NT and CT, while TOC was significantly higher in NT than in CT (22.54 and 12.17 Mg/ha or 34.16 and 22.90 Mg/ha, considering the organic layer plus mineral layers at 0–10 and 0–20 cm depth (set of two depths). The NT practice led to significantly higher concentration of labile C fractions (POC, AC and HWC) than CT at 0–10 cm soil depth. These results indicate that measurement of labile soil organic C fractions, such as POC, AC and HWC, may provide a sensitive and consistent indication of changes in soil C and SOM dynamics in response to soil management practices. Overall, NT seems to ensure better soil quality than CT in chestnut orchards under Mediterranean climate conditions.     

云南板栗早实性研究

实生板栗幼树从定值后第3年开始地径和树高生长超过嫁接苗。平均地径、树高和冠幅以永仁实生板栗最大。实生板栗早实性仅表现在形成雄花序和雌花簇，定值后第4年所有实生板栗幼树所结的球苞均为空苞，并以永仁实生板栗平均单株球苞数量多。达到104．6个。     

锥栗农家品种栗疫病抗性及果实表型性状的变异分析与联合选择

[目的]比较分析锥栗不同农家品种在栗疫病抗性、果实主要表型性状及营养成分等方面的差异情况,筛选出对栗疫病有较强抗性且果实品质表现优良的农家品种,从而为锥栗的良种选育提供参考依据.[方法]对锥栗疫病的病原菌进行形态学和核糖体DNA-ITS序列鉴定,在此基础上,对17个锥栗农家品种栗疫病抗性和果实表型性状指标(包括栗疫病染...