•Tree height predictions support critical forest management decisions.•Generalized mixed-effects h-d models for sweet chestnut were developed.•Richards nonlinear mixed-effects model showed the best ...prediction performance.•Draudt method, the best for calibrated predictions of tree height at plot level.
Height is a key variable for forest management. However, tree height measurements are expensive and time-consuming, requiring more effort to measure in the forest than diameter breast height measurements. Indeed, height-diameter (h-d) models are increasingly used to overcome the difficulty in measuring tree heights. Therefore, more accurate h-d models are increasingly needed. The mixed-effects modeling approach is a mainstream method to estimate h-d models. This technique was used to model the h-d relationship in the first 24 years of growth of sweet chestnut (Castanea sativa Mill.) high-forest stands for timber production. A dataset of 10,868 h-d observations and 57 plots of local-inventory data were considered individually. Simple mixed-effects models considering a grouping structure in the data (plot-level) were obtained, and generalized mixed-effects models were developed by expanding the fixed structure of simple mixed-effects models with stand-level variables. Several alternative model forms were tested in terms of accuracy, applicability and measurement effort. Different alternatives for calibrated predictions of tree height at plot level were analyzed, and considerations on the trade-off between easy-to-use equations in the field practice and high-accuracy equations for forest inventory were tested. The selected Richards M1a generalized mixed-effects model simultaneously provides fixed and random parameters to estimate the chestnut tree height from tree diameter and stand-level variables using the same model. The analysis showed that the inclusion of dominant height and dominant diameter as predictors improved the accuracy of the Richards model. The Draudt method was one of the best approaches to improve tree-level height prediction accuracy using mixed-effects. The applied approach is quite feasible in 100–500 m2 plots. The use of these models and the suggested calibration process will significantly reduce the effort and costs of fieldwork teams to measure heights for forest management planning while ensuring high accuracy. This effort is greater the greater the forest density and, therefore, greater for young stands than for adult stands.
The areas occupied by the common chestnut tree, Castanea sativa Mill. are continuously declining on an international scale. In Morocco, the chestnut trees are present in a restricted geographical ...area in the North and remains relatively unknown in the rest of the kingdom. This study represents the first contribution to the characterization and the evaluation of phenotypic similarities among Moroccan populations of Castanea sativa Mill. through univariate and multivariate statistical analysis of quantitative parameters and qualitative descriptors of fruits. The analysis was conducted on 13,455 fruits from 299 trees distributed across 31 populations from three regions. Ten qualitative descriptors were evaluated: nut shape (NSh), nut size (NSz), area of pubescence on upper part (AP), area of hilum (AH), shape of border line of hilum and pericarp (BSh), color of skin (CSk), glossiness (Gl), kernel color (CKr), coat adherence to kernel (CoA), and kernel inner-cavity (KC). In addition, the number of fruits/cupule (N/B), the number of fruits/kilo (N/K), and the average weight of fruits (W) were measured along with 11 quantitative parameters: nut length (NL), nut width (NW), nut thickness (NT), hilum length (HL), hilum width (HW), NL/NW, NT/NL, NT/NW, NW/HL, HW/NT, and HW/HL. The results of statistical analysis conducted on the 24 quantitative and qualitative parameters studied (ANOVA and SNK mean comparison test) demonstrated a very highly significant intra and inter-population variability for all the studied parameters. The correlation matrix analysis of the 12 quantitative parameters reveals a strong correlation between the fruit and hilum measurements, specifically NL, NW, NT, HW, and HL. Principal Component Analysis (PCA) and UPGMA analyses have shown the structuring of the 31 populations subdivided into two groups with subgroups, indicating significant diversity. The overall results highlighted a high genotypic variability of Moroccan populations of the chestnut trees and can be used to develop programs that aim to preserve the existing genetic variability of the chestnut tree and establish an in-situ collection of genetic resources in a geographically restricted area in the North of Morocco.
•Characterization of seasonal, daily and hourly chestnut burr growth.•Burr showed higher growth rate in the last part of the season (September-October).•Daily burr development was characterized by ...night-swelling and daily-shrinkage.•Burr daily net growth was phenologically dependent on environmental parameters.•Atmosphere humidity was the main microclimate driver of burr daily growth.
Chestnut crop is regaining its fame worldwide with powerful investment perspectives. Unluckily the climate change effects are posing high threat to its cultivation with less available resources and increased production cost both in traditional and specialized orchards. Additionally, the chestnut physiological knowledge is still limited, especially as concern the burr development (i.e., the economical production target) and its relationship with the environmental parameters. The aim of the present study was to evaluate the seasonal, daily, and hourly burr growth pattern associated to environmental parameters for improving physiological knowledge on this species. The study was carried out in a traditional rainfed sweet chestnut orchard located in the Tuscan-Emilian Apennines (Monterenzio, Italy). The chestnut burr growth was measured, along the entire season, both with a digital calliper and through the use of plant-based sensors (fruit-gauges) that permitted to measure, in real-time, the burr growth pattern. Environmental data were recorded by a weather station placed in the middle of the orchard. Results evidenced a higher burr growth rate, in the last part of the season (from middle-end of August to full fall) while the daily growing pattern was characterized by increased oscillation, along the season, of night-swelling and daily-shrinkage. The night-swelling was found to be influenced by high nocturnal air relative humidity while the daily-shrinkage was influenced by the higher wind speed, solar radiation and vapour pressure deficit. Thus, the burr daily net growth can be associated, depending on the phenological stages, to environmental parameters. Precipitation but especially the atmosphere humidity, in September and October, were the main external drivers of burr daily net growth. These results could be promising for the adoption of sustainable (e.g., late season grass mowing, sprinkler irrigation) and smart practices for improving chestnut management in both traditional and specialized orchards.
•A clear separation emerged between the Spanish and the Italian chestnut trees and among samples belonging to north and south of Spain.•Northern Italy and the Galicia region are the geographic areas ...where the genetic variability is more homogenous and preserved being derived by chestnut spontaneous establishment.•Wild and domesticated chestnuts trees from Iberian Peninsula and Italy showed no significant structure genetic differences.
The only native species of the Castanea genus in Europe is Castanea sativa Mill., a widespread and important multipurpose tree species in the Mediterranean area that provides fruit, wood and shelter for hives. With the aim of expanding the knowledge of the genetic variability of the chestnut species (wild trees and varieties) and promoting the traceability of local products, an analysis based on 16 SSRs was carried out on 630 single trees from Italy and Spain. 319 unique genotypes were identified. A Bayesian approach combined with the Markov Chain Monte Carlo (MCMC) simulation method revealed the existence of two genetically distinct groups of chestnuts: Cluster 1 (Spain) and Cluster 2 (Italy), with a clear separation between the cultivars from (northern and southern) Spain and from Italy. The results also confirmed a common genetic structure between chestnut populations from southern Spain and southern Italy, which is the result of historical events and long-term human impact. The results showed no genetic differentiation between chestnut cultivars (grafted trees) and wild chestnut trees, probably as a consequence of the proximity of orchards and natural populations, which resulted in a gene flow between them.
•A dynamic growth model for sweet chestnut.•Transition functions for basal area, dominant height and stand density.•Model explained > 90% of variability.•New above-ground biomass equation tool ...developed.•Novel stand-level Biomass Expansion Factor for sweet chestnut.
Sweet chestnut coppice (Castanea sativa Mill.) is a species of great importance in the northwest of Spain, due to its potential for producing valuable timber in relatively short rotations. However, abandonment has resulted in unstable and degraded stands. Thus, there is a need to improve forestry decision making tools. The objective of this study is the development of a dynamic stand growth model for the sweet chestnut comprised of three transition functions (dominant height, basal area and number of stems per hectare). They are used to estimate rates of change in the stand between an initial point in time and a point in the future. The data comes from two inventories of an unmanaged network of plots which incorporate all the variability in conditions in the region for the study species (climate, soil, stocking, site quality etc.). ADA and GADA approaches were used to develop the three transition functions. The model achieved high accuracy (explaining >90% of variability). The model incorporates an initialization function (explaining 60% of variability) for predicting initial stand basal area in stands without diameter inventories, which can be used to establish the starting point for the simulation, and, in addition, the biomass expansion factor (BEF) for this species (expressed as a constant value of 0.60) and a new single aboveground biomass equation (explaining almost 80% of variability) were calculated. A case study shows how to apply these decision making tools for the sustainable management of sweet chestnut coppice.
The effect of drying conditions on morphological and chemical properties of two Portuguese
Castanea sativa varieties (Longal and Martainha) was evaluated. All chestnut drying curves were found to be ...different according to drying temperatures (40
°C, 50
°C, 60
°C and 70
°C). Those conditions also affected both chemical composition of flours and morphological properties of starch. Colour parameters of the flours (
L∗
c∗
h°) generally decreased with increasing drying temperature, total colour difference (TCD∗) also significantly changed for samples dried at different tested conditions. The drying temperature seems to affect starch morphology, with Longal starch granules always somewhat smaller. The results showed that the higher the drying temperature, the higher the reducing sugars content and the lower the starch content. In what concerns differences among the studied varieties, it can be stated that Longal presents whiter flours, higher reducing sugars content, lower starch and sucrose contents. In opposition, Martainha flours presented lower percentage of amylose and damaged starch. From the results it can be concluded that the marked effects that drying temperature exerted on the characteristics and properties of chestnut flours are different in both varieties studied.
The effect of sweet chestnut (Castanea sativa Mill) flour in stimulating the growth of probiotic bacteria in fermented skim milk produced with different probiotic strains, namely Lactobacillus ...acidophilus, L. rhamnosus and Bifidobacterium animalis subsp. lactis was evaluated. Microbial counts, pH, total titratable acidity (LA %) and syneresis were measured in fermented skim milk samples. Additionally, the antioxidant capacities of the samples were measured by Trolox equivalent antioxidant capacity (TEAC), free radical scavenging activity (DPPH), and Ferric Reducing‐antioxidant Power (FRAP) assays. The viability and growth proportion index (GPI) of L. rhamnosus were significantly higher than those of L. acidophilus and B. lactis in all samples during storage. Results indicated that all probiotic fermented milks enriched with chestnut flour displayed significant probiotic viability (>7 log10 cfu/g) with high antioxidant capacities. L. acidophilus, L. rhamnosus and B. lactis survived throughout the shelf life of the chestnut‐fermented skim milk, and remain at this satisfactory viability level even after 21 days of storage. The antioxidant capacity and phenolic contents were dependent on probiotic strains used.
Practical applications
Nowadays the focus is rather on the effects of foods on maintenance of health, well‐being and prevention of certain diseases than simply satisfaction of appetite or nutrition. The consumers’ health consciousness due to the scientific knowledge of the interactions between diet and health is a driving factor to develop products with health‐related claims such as probiotic foods. This paper investigated the effects of chestnut flour supplementation not only on viability of probiotic bacteria but also the antioxidant capacity and phenolic contents in fermented milk throughout predicted shelf life. The results indicated that chestnut flour could be used as prebiotic for further researches to develop dairy products to deliver probiotics.
•HPP at 600 MPa for 5 min avoided molds and larvae growth on chestnuts.•The shelf-life of chestnuts treated at 600 MPa was extended in 40 days compared to HT.•Chestnuts treated by HPP preserved ...better their nutritional composition.•Softer texture and dark color observed on kernel chestnuts processed by HPP.•HPP processed chestnuts could be peeled more quickly and easily.
High-pressure processing (HPP) is an emergent technology for nonthermal pasteurization of foods, which here demonstrates the potential to be used by the chestnut industry. This study evaluated HPP as a post-harvest processing technology to control molds and insect larvae proliferation in chestnuts (Castanea sativa Mill.) and improve the fruit's shelf-life. Chestnuts were processed by HPP (400, 500, and 600 MPa for 5.0 min at 20 °C) and the conventional hydrothermal technology (HT, 50 °C for 45 min). Untreated chestnuts were also used as a control group. Shelf-life studies were conducted for 60 d at i) 25 °C and 40 % relative humidity (RH); and ii) 5 °C and 70 % RH. After the treatment and over the storage period, parameters such as color, texture, weight loss, nutritional composition, ascorbic acid, and fungal load were evaluated. The results showed that immediately after the HPP treatments, the chestnuts became slightly softer than HT samples. Fruit treated by HPP maintained their nutritional composition and ascorbic acid content. During the first 30 d of storage, no changes of color were observed in treated fruit. Also, the shelf-life of chestnuts treated at 600 MPa was extended by 40 d, compared to HT, where no molds at a detectable level and insect larvae were observed when stored at 5 °C. This storage condition also reduced the fruit weight losses. Compared with HT, HPP has short processing times, which is an important advantage. In addition, the observed changes of texture as softening and easy peeling can be useful for obtaining ready-to-eat products since chestnuts looked partially cooked. However, its possible application at the industrial level should be adequately investigated based on the promising results obtained.
In this study, chestnuts were processed into flour, and the obtained chestnut flour (CF) was passed through a sieve with an aperture size of 212 µm. Then the physicochemical properties, digestible ...and resistant starch contents of CF1 (<212 µm), CF2 (≥212 µm), and commercial chestnut flour (CCF) were determined. It was found that CCF had the highest values in terms of proximate composition, total soluble polyphenol content (891.25 mg GAE/100 g), and antioxidant activity (ABTS: 1552.11 mg TE/100 g, DPPH: 2003.01 mg TE/100 g). On the other hand, CF1 was superior in terms of resistant starch content (39.31 g/100 g, dw) (
< 0.05). The resistant starch content of CF1 was approximately 1.5-fold and 3-fold higher than CCF and CF2, respectively. Furthermore, the rapidly digestible starch content of CF1 (2.1 g/100 g, dw) and CF2 (0.93 g/100 g, dw) was quite lower than CCF (12.64 g/100 g, dw) (
< 0.05). Moreover, CF1 exhibited lower (
< 0.05) water, alkaline water, and sodium carbonate retention capacities, which make it a potential good flour for cookie and cracker production. In contrast, CF2 could be evaluated as a good ingredient for noodle-type foods due to its lower water solubility index. Considering the least gelation concentrations of samples, it was seen that CF1 (% 10) could also be valorized as a thickening or gelation agent in the food industry, as well as CCF (% 6).
•A huge dataset was collected from both field and laboratory analysis.•Infinite slope model was modified to include root reinforcement.•A Monte Carlo approach was used to manage the natural ...variability.•Beech communities have proved to be the most stabilizing forest in the tested cases.•The framework is replicable for other comparisons.
It is well known that forests play a crucial role in preventing soil erosion and landslides; however, forests are also subjected to dynamic evolution driven by natural processes and anthropogenic factors. This dynamic evolution affects spruce and chestnut forests in some European regions (e.g., Italian Alps, central and northern Europe), where these species have been forced by management practice to establish over long periods where other species, such as European beech, would be expected to occur as a result of natural processes.
Using a large dataset of field and laboratory measurements of root density and root mechanical properties, the performances of Norway spruce, Sweet chestnut and European beech are analyzed from a slope stability perspective by using a model based on the limit equilibrium principle within a probabilistic framework.
The results showed differences and similarities between the root systems of the analyzed species, both in terms of root distribution and mechanical properties. However, the probabilistic distribution that better fits the root reinforcement values obtained by the experimental work is, in all cases, a lognormal function.
The developed method can be used to estimate the factor of safety for several combinations of geotechnical and hydrological parameters and different root reinforcement probability distributions using Monte Carlo techniques. The obtained values have been evaluated in terms of probability to have a factor of safety of less than 1 for increasing values of slope steepness.
Although each single hillslope should be studied individually to account for local stand conditions that strongly affect root system performance, European beech is generally more efficient than Sweet chestnut and Norway spruce in terms of enhancing slope stability.
Based on our results, in all cases where the stability of slopes represents a concern and spruce and chestnut communities are perishing, the natural colonization by European beech should be evaluated positively and possibly promoted by forest managers. Moreover, the developed method provides a general framework that could be applied to other species and conditions to define the consequences of different forest management scenarios in terms of slope stability.
