Figure 2 - uploaded by Maurizio Marchi
Content may be subject to copyright.
-Characterization of site quality of walnut (Juglans sp.) of the Woodnat database from Italy and Spain, according to the site classes defined by Cisneros at al. (2008).
Source publication
Walnut tree species (Juglans spp.) are commonly used for high-quality wood production in plantation forestry. In this paper, the most relevant walnut plantations in Italy and Spain have been reviewed and analysed under a geographic and techni- cian management point of view. Between 2016 and 2019 a total of 96 plantations (15 - 25 years old) were vi...
Contexts in source publication
Context 1
... average marketable timber volume per tree in Italy was 0.118 m 3 with superior volume in younger polycyclic plantation and around 0.144 m 3 while, in Spain, single-tree volume reach and average value of 0.09 m 3 (±0.037) in pure plantation with similar age. The relationship between the average DBH values and age is shown in Figure 2 and compared to the site quality curve for walnut plotted using the methodology applied by Cisneros et al. (2008). According to our data 19 plots were referred to class I, 47 were close to class II and 30 allocated in class III. ...
Context 2
... average marketable timber volume per tree in Italy was 0.118 m 3 with superior volume in younger polycyclic plantation and around 0.144 m 3 while, in Spain, single-tree volume reach and average value of 0.09 m 3 (±0.037) in pure plantation with similar age. The relationship between the average DBH values and age is shown in Figure 2 and compared to the site quality curve for walnut plotted using the methodology applied by Cisneros et al. (2008). According to our data 19 plots were referred to class I, 47 were close to class II and 30 allocated in class III. ...
Citations
... Based on the morphological features of leaves, flowers, and fruits, the genus Juglans has been categorised into four sections: Rhysocaryon, Cardiocaryon, Trachycaryon and Dioscaryon (McGranahan and Leslie, 1991;Lu et al., 1999). The Persian walnut, also known as the English walnut, is the sole species to occur in section Dioscaryon and is one of the utmost prevalent and highly used forest tree species in tree farming activities due to the abundance of tradable nuts and top-quality timber (Tsoukas et al., 2015;Pollegioni et al., 2015;Pelleri et al., 2020). ...
A comprehensive evaluation of the morphological variation of naturally occurring Persian walnut (Juglans regia L.) in the North-Western Himalayan region of Indian Himalayas was carried out during 2021–2023. In the present investigation, 60 walnut genotypes from 12 distinct sites were analyzed for quantitative and qualitative (UPOV-TG/125/6) traits of tree, leaf, and nut to determine the diversity and select promising walnut genotypes. The results showed considerable morphological variation among the genotypes, where tree height (Th), circumference at breast height (Cbh), crown length (Cl), branching height (Bh), nut weight (Nwt), nut length (Nl), nut thickness (Nt), and total nut yield (Tny) varied significantly from 8.50 to 23.00 m, 90.00 to 370.00 cm, 4.00 to 12.00 m, 3.00 to 16.00 m, 6.60 to 37.30 g, 25.51 to 36.19 mm, 23.64 to 39.60 mm, and 32.00 to 85.00 kg, respectively. Among tree traits, Th exhibits a significant positive correlation with Cbh, Bh, Cl, number of branches (Nb), crown width, and Tny, and among nut traits, Nwt has a positively significant correlation with Nl, nut width (Nw), and Nt. The results of the principal component analysis indicated that characteristics such as Th, Bh, Nw, Nl, and Nwt contributed to a significant proportion of the observed phenotypic variation and reduced the examined traits to four main principal components alone, which accounted for 71.22 per cent of the overall variance. The genotypes were grouped into four distinct groups by subjecting them to cluster analysis. The genotypes DML-I, DML-II, GSN-I, DKD-I, CHK-III, and CHN-V were identified as superior/promising on the basis of mean data, multivariate analysis (PCA) and selection index involving valuable traits with regard to wood and nut traits. Further investigation of these genotypes using the new genomic breeding approaches is highly desirable considering their beneficial role in walnut breeding.
... Eighteen years represent about a third of the rotation of c. walnut trees for timber production in Italy [35]. The above mentioned DBH increment corresponds to what reported on average for the timber plantations of c. walnut recently surveyed in Italy and Spain [36], for the 2 nd fertility class of c. walnut plantations. ...
Agroforestry systems with multipurpose tree species, for the double production of timber and fruit, along with the intercropping with herbaceous crops, can be fundamental land use systems for multiple ecosystems services. Research was conducted in Italy, for one growing season, in 18 years old agroforestry experimental plots with common walnut (Juglans regia L.) trees, according to the previous agroforestry management (AFM) since tree planting. The aim is i) estimating trees growth and herbaceous yield in relation to increasing tree size, especially referring to the trees basal area (G); ii) evaluating the role of nut production as additional product to timber and food crops. Observations were run on tree growth and leaf phenology, total light transmittance (TTL) below tree canopy and hay yield with and without walnut intercropping. Nut yield was estimated from available literature and associated to G. At the end of the study year, representing two third of trees rotation, their height varied between 10 and 11 m, with much larger variation for tree diameter between 17 and 22 cm, according to the previous AFM, including tree mulching with plastic film. Hay yield varied between 4.5 and 3 Mg ha year-1 outside and under tree canopy, respectively. Negative regression were determined for G and TTL, and G and hay yield, with an annual reduction of 5% per G unit. Simulations were run on hay and nut yield, using G as main input parameter. The work points out the following key findings: i) the usefulness of plastic mulching, at tree planting, to increase the long-term timber productivity of the trees intercropped with herbaceous crops; ii) the negative linear relationship between hay productivity and walnut trees G; iii) G influences, in positive way, more markedly nut than hay yield. Suggestions are given on the optimum tree planting spacing and AFM for balancing timber, nut and hay yields.
... Walnut-based ACS with winter crops Black walnut has been utilized for timber in Europe since first introduced in the 17th century and is grown for timber on an estimated 20,000 ha across 14 European countries (Šálek and Hejcmanová 2011;Goodman et al. 2013;Nicolescu et al. 2020;Pelleri et al. 2020). In addition to the high-quality wood, European growers note that black walnut trees better resist pests, diseases, and drought conditions than J. regia (Salek & Hejcmanova 2011). ...
Agroforestry adoptition is gaining considerable traction in the temperate US with growing popularity and government incentives (e.g., the Partnerships for Climate-Smart Commodities Project) for systems with greenhouse gas mitigation potential. The identification of complementary species combinations will accelerate the expansion of temperate agroforestry. Since the mid-19th century, European timber plantations have taken advantage of the late-leafing habit of walnut ( Juglans spp.) to grow a spring grain crop between the tree rows. Such alley cropping systems increase land-use efficiency and provide extensive environmental benefits. A parallel but underutilized opportunity in North American involves incorporating eastern black walnut ( Juglans nigra L.) cultivars into alley cropping systems (ACS). Eastern black walnut, henceforth referred to as black walnut, is native to North America and exhibits architectural and phenological characters for reduced competition with winter cereal crops grown in alleys. Black walnut also produces nutritious nuts, and cultivars with improved kernel percentage and mass offer potential to cultivate the species as a domesticated orchard crop, as opposed to just the high-quality timber for which it is well-known. However, field observations suggest significant variation in tree architecture and phenology amongst cultivars, which is likely to influence complementarity with winter grains. Comprehensive characterization of trait genetic diversity is needed to best leverage germplasm into productive systems. Here, we review literature related to implementing ACS with consideration of cultivar-dependent traits that may reduce interspecific competition. While the focus is directed toward black walnut, broad characterization of other underutilized fruit/nut species will allow for robust diversification of ACS.
... Afterwards the selection of the best 70-80 crop trees per hectare (common oak and other valuable tree species) was carried out in the whole plantation. The best valuable trees were selected and marked, considering tree vigor (evaluated according to the diameter dimension and crown development, Wilhelm and Rieger 2017), stem quality (according to CEN standard, Nosenzo et al., 2012) and potential timber value (according to Pelleri et al., 2020) as well as the ground distribution. In general, common oak was favored as species most suitable for the local site condition. ...
Thinning intensity is an important factor affecting forest structure and density and influencing tree growth.
The main objective of the study is to evaluate how the different intensity of thinning can influence, in the short and long term, the productivity and intrinsic water use efficiency (WUEi) of Quercus robur L., a widespread European species. Three thinning types of different intensity were applied in 14-year mixed plantation of Quercus robur L. growing with Alnus glutinosa (L) Gaertn., a N-fixing species, with an initial density of 625 trees/ha. A multidisciplinary approach was applied, coupling the tree-ring analyses with the measurements of stable isotopes of carbon and oxygen.
Findings highlighted how the different conditions of light and competition, determined by the type and intensity of thinning, triggered different responses of Q. robur species in terms of growth and WUEi.
Data suggested that the moderate selective thinning (31% reduction of total biomass) was not able to reduce the high competition for resources among individuals: this condition negatively influenced the trees growth. The presence of the N-fixing species, left after the thinning, was not able to counteract the negative effect of competition.
A negative effect on productivity was recorded with the geometric thinning (62% reduction of total biomass). Indeed, this treatment resulted in an increase of asymmetry of the canopy (0.90 vs 0.83, respectively in pre- and post-thinning period), due to the partial crown competition from one side and with a consequent limitation of the photosynthetic activity of the trees. Finally, the very high selective thinning (75% reduction of total biomass) resulted to be the most appropriate management practice, as it guarantees positive effects both in terms of growth and intrinsic water use efficiency. The post thinning conditions determined high photosynthesis rates, an increase of productivity and a limited water loss.
Six broadleaf tree species (Celtis australis L. – Mediterranean hackberry, Quercus petraea (Matt.) Liebl. – sessile oak, Fagus sylvatica L. – European beech, Prunus avium L. – wild cherry, Juglans regia L. – Persian walnut and Acer pseudoplatanus L. – sycamore maple) were planted in 2012 in a trial in the Slovenian Karst on two sites differing in productivity to test their suitability for use in the conversion of old pine stands into ecologically more stable broadleaf forests and to investigate their possible response to the harsher growth conditions predicted in the future. The selected economically interesting tree species have higher timber quality than broadleaves which regenerate naturally (e.g., Ostrya carpinifolia, Fraxinus ornus, Quercus cerris). Measurements were taken in 2017, after four growth seasons. All planted species except Fagus sylvatica had a high survival rate. In total, 70% of all seedlings survived, which shows promising potential. The survival rate was higher at the site on flat terrain than at the site on a slope. Prunus avium was the most successful of all planted species in terms of survival rate, at 83%, and other measured parameters (height, height increment, stem diameter, vitality and quality), and Fagus sylvatica was the least successful, with a survival rate of only 20%. Celtis australis had the highest survival rate, at 87%. Acer pseudoplatanus had the largest differences in measured parameters between the more and less productive sites among all planted species. Quercus petraea showed high resistance to xeric conditions and is expected to be the most successful in conversions. All planted species except Fagus sylvatica show favourable initial potential for the future conversion of Karst pine forests.
Aim of study: To verify the short rotation coppices (SRC) aboveground biomass production; to define the best planting intra-row spacing for walnut and poplar growth and wood production, with the last goal to assess the possibility of obtaining competitive yields in comparison to those produced by traditional monocultures.
Area of study: Po Valley, municipality of Meleti (Northern Italy).
Material and methods: A randomized block design with three replications was applied for the experimental design. The growth-monitoring activities started in 2009 and have continued for 5 years on the SRC, 10 years on poplar clone ˈI-214ˈ, whereas on common walnut they are still going on but only data concerning the twelfth year are reported in this work. The normality of distribution was evaluated for growth and yield data of species in the SRC model; all data were analysed with ANOVA; growth data were included in a linear mixed model analysis to evaluate the effect of age, spacing and their interaction, and the effect of SRC rows on growth and yield of poplar and walnut.
Main results: After 5 years of cultivation under SRC system, biomass yields obtained from the poplar clone ˈAF2ˈ were 39.9 Mg ha-1, from the elm 31.9 Mg ha-1 and from the plane 14.8 Mg ha-1. After 10 years high timber production was obtained from poplar clone ˈI-214ˈ (average volume 98.2 m3 ha-1). After 12 years, walnut trees reached a diameter at breast height (DBH) of 17.8±0.2, 18.9±0.2 and 18.7±0.3 cm, respectively, for planting distances of 6, 7 and 8 m, and showed diameter increments of 1.5-2.0 cm yr-1. With these growth rates, walnut can reach a merchantable dimension within 25-30-years.
Research highlights: Polycyclic wood plantations are a recent arboriculture model able to produce, on the same site, different assortments using various crop trees characterized by different growth rates and turnovers. This new type of mixed plantation is more environmentally sustainable compared to monoculture and allows diversification of production, obtaining continuous wood yields over the years (5, 10, 20, 30 years).
Species interactions in mixed plantations can influence tree growth, resources capture and soil fertility of the stands. A combined approach of tree-ring analyses and carbon stable isotope was used to check tree growth and water use efficiency of two species, Populus alba L. and Juglans regia L., intercropped with each other and with N-fixing or competitive production species. Furthermore, soil analyses were performed to understand how the different intercropping systems can influence soil characteristics, in particular soil carbon stock. Dendrochronological data showed that during the first years, the growth of principal species was favored by intercropping. This positive effect decreased in the following years in most of intercropped stands, due to light competition with the crown of companion species. Carbon isotope data showed that P. alba and J. regia had the highest intrinsic water use efficiency when growing with Elaeagnus umbellata Thunb, a shrubby species with a shallow root system that favors a non-competitive exploitation of soil water resources. Finally, the intercropping of the principal species with Corylus avellana L. promoted the highest soil C stock. Our findings confirmed the importance to consider the plantation dynamics and wood formation in the long-run and to apply appropriate thinning and pruning interventions to counteract interspecific competition.
The paper describes the principal techniques and cultural models suitable for common walnut cultivation pointing out the high potentiality of this tree and the limitations of walnut cultivation.
The walnut twig beetle Pityophthorus juglandis is a phloem-boring bark beetle responsible, in association with the ascomycete Geosmithia morbida, for the Thousand Cankers Disease (TCD) of walnut trees. The recent finding of TCD in Europe prompted the development of effective diagnostic protocols for the early detection of members of this insect/fungus complex. Here we report the development of a highly efficient, low-cost, and rapid method for detecting the beetle, or even just its biological traces, from environmental samples: the loop-mediated isothermal amplification (LAMP) assay. The method, designed on the 28S ribosomal RNA gene, showed high specificity and sensitivity, with no cross reactivity to other bark beetles and wood-boring insects. The test was successful even with very small amounts of the target insect’s nucleic acid, with limit values of 0.64 pg/µL and 3.2 pg/µL for WTB adults and frass, respectively. A comparison of the method (both in real time and visual) with conventional PCR did not display significant differences in terms of LoD. This LAMP protocol will enable quick, low-cost, and early detection of P. juglandis in areas with new infestations and for phytosanitary inspections at vulnerable sites (e.g., seaports, airports, loading stations, storage facilities, and wood processing companies).
Within the activity of the H2020 'WOODnat' project ("Second generation of planted hardwood forests in the European Union") the growth parameters, yield and sanitary conditions of the most important walnut (Juglans spp.) plantations, established in Italy in the 1990s and in Spain starting from 1996, were recorded. One of the objectives of the project was to evaluate tree growth and stem quality to derive insight on the main environmental factors affecting the production of this valuable specie. An inventory of walnut plantations in the area of interest was necessary due to the relevance of this tree species in the EU timber market. In this paper the final dataset is presented and available with DOI: 10.5281/zenodo.3769940. The database is finalized to narrow the knowledge gap between growers and processing industry with the aim to relaunching the market for this valuable species. Data were collected in the spring 2017 and winter 2017-2018 on 27 stands established in Northern Italy (Piemonte and Lombardia), on 51 stands in Central Italy (Toscana and Marche) and on 17 stands in Spain for a total of 95 plantations. In each plantation, general information was collected such as the planting layout, spacing, age, environment conditions as well as tree-level dendrometric data and phytosanitary information. The sampled stands have been georeferenced in WGS84 reference system (EPSG 4326). These data can be exploited to assess potential wood volume obtainable and quality of raw material, and to identify the weaknesses and errors, strengths and opportunities of the experiences conducted to plan future plantings with greater awareness..
