Chestnut Plantations Research Articles

Damage to Sweet Chestnut Orchards in Croatia due to Invasive Alien Bark Beetle Xylosandrus germanus

Black stem borer, Xylosandrus germanus (Coleoptera: Scolytinae), was first recorded in Croatia in 2009. Until now, the insect has been reported only as a part of ambrosia beetles entomofauna in oak stands (Quercus robur and Quercus petraea). In 2021, severe attack of ambrosia beetles causing tree decline and mortality have been observed in three orchards of hybrid sweet chestnut (Castanea sativa x Castenea crenata). Orchards near Topusko, Marija Bistrica and Vugrovec were inspected for the symptoms. Twenty-seven adult ambrosia beetle specimens were collected from eight samples of damaged sweet chestnut trees, and were identified according to their morphology. All 27 ambrosia beetles were morphologically identified as X. germanus. This is the first record of black stem borer causing damage on cultivated sweet chestnut in Croatia. Considering similar reports from Italy and Slovenia, X. germanus could be regarded as a new, potentially damaging pest in chestnut plantations.

Detection and Mapping of Chestnut Using Deep Learning from High-Resolution UAV-Based RGB Imagery

The semantic segmentation method based on high-resolution RGB images obtained by unmanned aerial vehicle (UAV) provides a cost-effective way to improve the accuracy of detection and classification in forestry. Few studies have explored the impact of sample distribution patterns on deep learning model detection accuracy. The study was carried out using the data from the 4.78 km2 RGB image of a chestnut (Castanea mollissima Blume) plantation obtained by the DJI Phantom 4-RTK, and the model training was conducted with 18,144 samples of manually delineated chestnut tree clusters. The performance of four semantic segmentation models (U-Net, DeepLab V3, PSPNet, and DeepLab V3+) paired with backbones (ResNet-34, ResNet-50) was evaluated. Then, the influence of chestnut data from different planting patterns on the accuracy and generalization performance of deep learning models was examined. The results showed that the combination of DeepLab V3 with ResNet-34 backbone gives the best performance (F1 score = 86.41%), while the combination of DeepLab V3+ with ResNet-50 backbone performed the worst. The influence of different backbone networks on the detection performance of semantic segmentation models did not show a clear pattern. Additionally, different spatial distribution patterns of chestnut planting affected the classification accuracy. The model MIX, trained on comprehensive training data, achieves higher classification accuracies (F1 score = 86.13%) compared to the model trained on single training data (F1 score (DP) = 82.46%; F1 score (SP) = 83.81%). The model performance in complex scenario data training is superior to that of the model in simple scene data training. In conclusion, comprehensive training databases can improve the generalization performance of chestnut classification with different spatial distribution patterns. This study provides an effective method for detecting chestnut cover area based on semantic segmentation, allowing for better quantitative evaluation of its resource utilization and further development of inventories for other tree species.

Effect of thinning on growth and shape of Castanea sativa adult tree plantations for timber production in Chile

Chestnut (Castanea sativa Mill.) is an interesting species for high-quality timber production. It is well known that the species responds to early thinning, but there is no information on the impact of late interventions. The objective of this study was to assess the effect of a late thinning on the performance of unmanaged adult chestnut plantations in Chile. Future-tree selective thinning and control were compared in adult plantations using a randomized complete block design with three replicates at three sites, Minas, Pillo-Pillo and Pumillahue. Tree growth was evaluated periodically during the first 7 years after thinning in all plantations. Additionally, almost 20 years after the intervention, the Pumillahue plantation was measured for growth and tree shape variables. In this case study, the effect of thinning on tree growth decreased considerably after 5 years, with a maximum DBH increment in the third year after the intervention (45.8 %, 68.6 %, and 42.2 % in Minas, Pillo-Pillo and Pumillahue, respectively). In all plantations, basal area was smaller in the thinned plots in the first years after the intervention, but in Pumillahue, 19 years after thinning, no differences were found among treatments. Height was statistically greater under thinning seven years after the intervention; this effect was also found in Pumillahue plantation 19 years after thinning. Most trees showed high vigor, and were straight and healthy, even in control plots. Late effect of thinning was observed 19 years after thinning on tree shape, with a reduction in the proportion of bifurcated trees from 16 % to 8 %. The results suggest that late thinning is an effective silvicultural intervention to produce high-quality chestnut timber in unmanaged adult plantations. Progressive and frequent thinning should be used to increase growth and improve timber production in chestnut.

THE MAIN FACTORS INFLUENCING THE DAMAGE AND POPULATION DYNAMICS OF CAMERARIA OHRIDELLA (DESCHKA & DIMIC, 1986) IN URBAN PLANTATIONS OF KYIV REGION

In Ukraine, the horse-chestnut leaf-miner (Lepidoptera: Gracillariidae, Cameraria ohridella Deschka & Dimic, 1986) was first discovered in 2002 in the Lviv region. Currently, the species is widespread in Ukraine and its range continues to expand. The consequence of the life activity of the miner lies in severe damage to the leaves and premature defoliation, negatively affecting the accumulation of reserves of nutrients necessary to maintain the vitality of plants in the winter and restore growth in the spring. The article provides data on the first detection and further spread of the invasive pest of horse-chestnuts C. ohridella in the world and on the territory of Ukraine. The phytosanitary condition of horse-chestnut trees (Aesculus hippocastanum L.) in the conditions of urban plantations in Makariv town, Buchansky district, Kyiv region in 2022 was studied. The data of the seasonal dynamics of the number of the pest, tracked with the help of pheromone monitoring, are given. In the course of route surveys of horse chestnut plantations, the phytosanitary condition of the trees on both sides of the road in the city of Makariv along Dmitriy Rostovsky Street and on the territory of the Makariv Lyceum No. 1 was assessed according to the following criterias: damage to the crown, the degree of damage to the leaf plates, and the overall vitality of the trees. The condition of each tree was assessed with a certain number of points according to the appropriate methods. According to the conducted surveys, it was found that the trees that were located on the isolated territory of the Lyceum suffered less damage from the phytophagus during the month and had significantly higher vitality and decorativeness, compared to the horse-chestnuts that grew along the road. Phytophage pheromone monitoring showed that the number of C. ohridella recorded in traps on both sides of the roadway on Dmitry Rostovsky Street significantly exceeded the number of insects caught on the territory of the educational institution. A clear inverse relationship between the number of insects caught and meteorological conditions was established: during heavy rains with high air humidity, the flight of the chestnut miner almost completely stopped, and the number of insects in the traps was close to zero, and vice versa.

Development of tools to estimate the contribution of young sweet chestnut plantations to climate-change mitigation

Sweet chestnut plantations, irrespective of their main productive orientation (nut or timber production), are key elements of the landscape as well as the cultural heritage of the areas where they are found and provide important functions and services. Hence, recent initiatives have been aimed at extending the area occupied by chestnut trees through forest plantations. Nevertheless, the role of these young chestnut plantations as carbon sinks has been often ignored. The National Inventory of Greenhouse Gas Emissions (GHG) must include estimates of the so-called ‘transition forests’ during the 20 years following their plantation.In this study, new tools for estimating the total amount of above and belowground biomass stored in young plantations of chestnut were developed to quantify the carbon storage capacity of these plantations. A new set of aboveground biomass and root-shoot ratio models were fitted for individual-tree level based on four different independent variables – root collar diameter, total height, diameter at breast height and crown projection area – and their combinations. The expansion to stand level was based on age, plantation density, productive orientation of the plantation (nut or timber), site index and climate covariates as possible independent variables. At tree level, the best aboveground biomass models were those that include the product of root-collar or breast height diameters and tree height, whereas for root-shoot ratio the best results were obtained when only diameter at breast height is included. At stand level, the most accurate models included age, plantation density and site index for aboveground biomass and only age for root-shoot ratio. The fitted models provided accurate and unbiased predictions of aboveground biomass in the first years of reforestations.The different fitted equations can be used to estimate carbon stocks in young plantations depending on the available data and the objective of the prediction. Individual tree-level equations are recommended when accurate estimates are needed and detailed inventory measurements are available. Stand level equations, only using plantation age, can be an appropriate alternative for use with forest statistics at national scale, although the inclusion of additional covariates can greatly improve the accuracy of the age-based stand level equations. Our results indicated that even low-density nut-oriented chestnut plantations can play a relevant role as C sinks.

Охридский минер Cameraria ohridella Deschka&Dimic: особенности инвазионных очагов и перспективы биологического контроля численности

The ecological mechanisms of one of the most dynamic biological invasions such as a colonization of artificial plantations of horse chestnut Aesculus hippocastanum L. by the ohrid miner, or chestnut miner Cameraria ohridella Deschka & Dimic (Lepidoptera, Gracillariidae) have been analyzed. The materials of publications on the bioecological features of C. ohridella in the conditions of native and invasive areas are summarized. The survey results of phytophage invasive foci in plantations of Moscow are presented. Particular attention is paid to the change in population characteristics (density, level of damage by entomophages) in connection with the biotopic conditions of horse chestnut plantations and meteorological features of the growing season. Measures to reduce the harm by C. ohridella by means of a biological control are considered. The information on the influence of various biotic factors on the phytophage is analyzed. Particular attention is paid to parasitoids as a means of the classical biological method. A suitable agent among parasitoids from natural foci of the miner has not yet been identified, and the level of local parasitism in European invasive foci is low. The perspective method of enhancing local parasitism through the accumulation and controlled release of parasitoids from leaf litter is substantiated. This technique makes it possible to synchronize the appearance of parasitoids with the phenology of the pest. This technology has already been tested by European researchers. Prospects are substantiated, the technology of seasonal colonization of parasits, which can be massively bred in biological laboratories such as parasitoids of Trichogramma (Hymenoptera, Chalcidoidea, Trichogrammatidae) and chrysopids (Neuroptera, Chrysopidae) is presented. Inside the invasive foci of C. ohridella, the effectiveness of seasonal colonization is proposed to be enhanced by using synthetic analogs of herbivore-induced plant volatiles (HIPV) that attract entomophages.

Monitoring of the Condition of Green Plantations in Shevchenkivskyi District of Kharkiv (on The Example of Bittle Chestnut (Aesculus Hippocastanum L.)

In the complex of measures for improving atmospheric air quality in a modern city and reduction of noise pollution, special emphasis is placed on outdoor green spaces, which primarily perform a sanitary and hygienic function, protect residents and urban sites from harmful transport emissions, localization and partially absorb them. Purpose. Monitoring the state of green spaces in the Shevchenkivskyi district of Kharkiv (for example, bitter chestnut (Aesculus Hippocastanum L.) Methods. Analytical and synthetic method, geoinformation (cartographic modeling and processing of remote sensing data), analysis of information sources and methods of field research. Results. Based on the analysis of literature and fund materials and our own field research, information was obtained on the current state of plantings of common bitter chestnut in the Shevchenkivskyi district of Kharkov. A visual assessment of the quality of common bitter chestnut stands was made, in particular, damage to trees was determined. An inventory map of urban plantations of bitter chestnut in the usual Shevchenkivskyi region was developed using GIS technologies. Recommendations have been developed to improve the ecological state of common bitter chestnut plantations within the Shevchenkivskyi district of Kharkiv. Based on the results of this study and taking into account the preliminary work of scientists, it has been proved that the development of an inventory map of urban plantings of common bitter chestnut makes it possible to find out information about the state of the city's green spaces (number, types, age, diseases and damage, etc.). Conclusion. The obtained data on green spaces can determine the priorities for the development of landscape design, an action plan for urban green infrastructure to adapt to climate change. Based on reliable data, you can draw up a quality plan for the development of urban greening.

Assessment of leaf damage degree in Aesculus hippocastanum L. during the growing season in the conditions of Dnipro city

One of the unique indicators of environmental pollution is Aesculus hippocastanum Linnaeus, 1753, distributed in different ecological conditions of most European cities in both the southern and northern temperate zones. For a long time bitter chestnut belonged to the number of highly resistant wood species. But in the last two decades, the condition of bitter chestnut plantations has deteriorated significantly due to the impact of adverse abiotic environmental factors (due to global climate change and increasing man-made load), and due to mass reproduction of phytophagous and phytopathogenic. A. hippocastanum especially suffers from chestnut miner (Cameraria ohridella Deschka & Dimič, 1986), for which it is the main forage plant. The aim of our study was to assess the degree of damage to the leaf surface of Aesculus hippocastanum L. during the growing season in the Dnipro. Analysis of damage to the leaf blades of the forage plant C. ohridella was performed for four years (2018–2021) visually on a modified scale proposed by M. D. Zerova et al. (2007). The research covered eight main park urban ecosystems of the Dnipro. Four stable generations of C. ohridella were established in the city of Dnipro. The development period of one separate generation of chestnut miner lasts from 65 to 110 days. The beginning of the flight of adults of the first generation occurs at the end of April and the beginning of May. Monitoring was carried out during three summer months, which corresponds to the main feeding period of the three most active generations of C. ohridella (I, II and III). A. hippocastanum leaf blades have been found to be damaged differently in different park urban ecosystems. The highest percentage of damage in all park areas is observed in August, when three generations were almost completely fed. A significant dependence of the area of affected leaves of bitter chestnut common invasive C. ohridella on the period of the growing season was found. According to our research, in all eight test plots, which corresponded to the main area and functional load of the green areas of the Dnipro, during the summer there is an increase in the area affected by the miner leaf in chestnuts. During the four years of observations (2018-2021), in the city of Dnipro, this generalized indicator ranged from 32% in June to 65% in August. This increase can be explained by the increase in the number of mines, due to the gradual emergence of the second and third generations of C. ohridella, each of which is more numerous than the previous one

Бактеріальна виразка — небезпечна хвороба каштана кінського в Європі

Goal. To analyze and summarize the data of harmfulness, methods of distribution, identification, and methods of control of the causative agent of bacterial ulcer of horse chestnut Pseudomonas syringae pv. aesculi (Young, Bradbury, Davis, Dickey, Ercolani, Hayward & Vidaver 1991a) and predict the possibility of introduction of this species in Ukraine. Methods. General scientific — for generalization, comparison, and system analysis; field — for visual inspection of street horse chestnut plantations. Results. The causative agent of P. syringae pv. aesculi came to Europe from India and as a result of adaptation to the climatic conditions of the European continent became more aggressive. The main symptom of the lesion is weeping necrosis on the trunk and main branches. Horse chestnut trees affected by this pathogen often die within 3–4 years. Identification of the pathogen can be done by amplification and sequencing of the gyr B gene. A common pest of chestnuts in Europe and Ukraine — chestnut moth, leads to greater damage to trees by bacterial ulcers, but the possibility of the pest to be a vector of P. syringae pv. aesculi not confirmed. The source of infection can be epiphytic populations of the pathogen, which are on the leaves and bark of horse chestnut trees. In Kyiv, among the street plantations of horse chestnut, there are trees with typical for bacterial ulcers lesions of the trunk. To confirm the presence of the pathogen in Ukraine, it is necessary to monitor horse chestnut plantations in different areas and laboratory confirmation of the pathogen identification. Preventive measures should be taken to prevent the spread of the pathogen. Conclusions. Phytopathogenic bacteria P. syringae pv. aesculi affect horse chestnut in all European countries. The status of the pathogen for Ukraine has not been determined yet. A promising method of pathogen control is the introduction of resistant to P. syringae pv. aesculi forms of horse chestnut.

Mid-term (30 years) changes of soil properties under chestnut stands due to organic residues management: An integrated study

Chestnut plantations are worldwide distributed and they are often subjected to intensive management practices such as the removal of the organic residues from the soil surface. The present study aimed to investigate the effect of such practices on soil properties at different depths and on nutrient contents in chestnut leaves. To reach our goal, 6 pits down to 30 cm soil depth were dug in European chestnut (Castanea sativa Mill.) stands where the organic residues such as burrs, leaves and pruned materials are yearly removed (REM), and 9 pits in stands where the organic residues are chopped and left on soil surface (CONS). Both practices began about 30 years ago. The nutrient contents in leaves were assessed on chestnut trees close to each pit. Our findings showed a more intense soil development in CONS than in REM. At soil surface, CONS had thicker mineral horizon than in REM probably due to the protection acted by the organic residues against erosion. In subsoil, organic residues conservation promoted the organic C (soil organic C, water–extractable organic C, fulvic–like C and soil organic C stock) accumulation which further promoted horizon development. Since the role of soil organic matter (SOM) as source of nutrients, the subsoil of CONS study sites had a greater stock of Ca, P and S and a higher exchangeable Ca content than REM. Furthermore, the higher SOM and nutrient contents in CONS subsoil compared to REM promoted the microbial respiration. The organic residues conservation effects on the surface soil horizon properties were, instead, negligible. Despite the generally better soil conditions in CONS than in REM, no differences were observed for the leaf nutrient contents likely due to the chestnut trees adaptability also to the scarcely fertile soils. Overall, our findings highlighted the importance of organic residues conservation for the improvement in deeper soil horizons of the chemical and biological fertility in chestnut plantations. Furthermore, this research pointed out to pay more attention on subsoil since it is a good indicator of the changes caused by external factors.

Detection of Very Small Tree Plantations and Tree-Level Characterization Using Open-Access Remote-Sensing Databases

Highly fragmented land property hinders the planning and management of single species tree plantations. In such situations, acquiring information about the available resources is challenging. This study aims to propose a method to locate and characterize tree plantations in these cases. Galicia (Northwest of Spain) is an area where property is extremely divided into small parcels. European chestnut (Castanea sativa) plantations are an important source of income there; however, it is often difficult to obtain information about them due to their small size and scattered distribution. Therefore, we selected a Galician region with a high presence of chestnut plantations as a case study area in order to locate and characterize small plantations using open-access data. First, we detected the location of chestnut plantations applying a supervised classification for a combination of: Sentinel-2 images and the open-access low-density Light Detection and Ranging (LiDAR) point clouds, obtained from the untapped open-access LiDAR Spanish national database. Three classification algorithms were used: Random Forest (RF), Support Vector Machine (SVM), and XGBoost. We later characterized the plots at the tree-level using the LiDAR point-cloud. We detected individual trees and obtained their height applying a local maxima algorithm to a point-cloud-derived Canopy Height Model (CHM). We also calculated the crown surface of each tree by applying a method based on two-dimensional (2D) tree shape reconstruction and canopy segmentation to a projection of the LiDAR point cloud. Chestnut plantations were detected with an overall accuracy of 81.5%. Individual trees were identified with a detection rate of 96%. The coefficient of determination R2 value for tree height estimation was 0.83, while for the crown surface calculation it was 0.74. The accuracy achieved with these open-access databases makes the proposed procedure suitable for acquiring knowledge about the location and state of chestnut plantations as well as for monitoring their evolution.

Gnomoniopsis chinensis (Gnomoniaceae, Diaporthales), a new fungus causing canker of Chinese chestnut in Hebei Province, China.

Chinese chestnut (Castanea mollissima) is an important crop tree species in China. However, branch canker and fruit rot are two kinds of severe diseases, which weaken the host and decrease chestnut production. During our investigations into chestnut diseases in China, several fungi have been confirmed as casual agents in previous studies, namely Aurantiosacculus castaneae, Cryphonectria neoparasitica, Cry. parasitica, Endothia chinensis and Gnomoniopsis daii. In this study, a new canker pathogen is introduced based on morphology, phylogeny and pathogenicity. Typical Gnomoniopsis canker sign of wide, orange tendrils emerging from hosts’ glaucous lenticels were obvious on the diseased trees in the field. Symptomatic branches or bark on stems from different chestnut plantations were sampled and isolated, then strains were identified by comparisons of DNA sequence data for the nuclear ribosomal internal transcribed spacer (ITS), partial translation elongation factor-1α (tef1) and β-tubulin (tub2) gene regions as well as morphological features. As a result, these strains appeared different from any known Gnomoniopsis species. Hence, we propose a novel species named Gnomoniopsis chinensis. Pathogenicity was further tested using the ex-type strain (CFCC 52286) and another strain (CFCC 52288) on both detached branches and 3-year-old chestnut seedlings. The inoculation results showed that Gnomoniopsis chinensis is mildly pathogenic to Chinese chestnut. However, further studies are required to confirm its pathogenicity to the other cultivated Castanea species in America, Europe and Japan.

Effect of Different Nitrogen Levels on Nut Yield and Some Quality Properties of Sweet Chestnut (Castanea sativa Mill.)

Chestnut has been used by humanity both as a fuel and as a food source for many years. Chestnut-related fertilization data is still limited today. This research was performed in order to study the fruit yield and some quality characteristics of the nitrogen doses to be applied in the chestnut plantations of İnegöl (Bursa) during two years. In the study, were used sweet chestnut (Castanea sativa Mill. cv. Sarıaasılama) trees 20 years old. During 2012 and 2013 the doses of 0.5, 1.0, 1.5 and 2.0 kg N / tree were applied to the chestnut experimental orchard, except for the control. However, 0.75 kg P / tree and 1.5 kg K / tree basic fertilization were applied to each tree. In the experiment, each parcel was composed of 3 trees and 3 replications. According to the results of the study, the highest fruit yield was recorded as 31.8 and 32.8 kg / tree in 1.5 kg N / tree in both application years respectively. Total protein and starch in the highest fruit were determined as 12.8 and 36.3 g / 100 g in 1.0 kg N / tree dose in the 2013 year, respectively. The total sugar content in fruit was recorded as 10.8 g / 100 g in 1.5 kg N / tree in 2013. When all of these parameters are examined, the amount of nitrogen to be applied to a mature chestnut tree at 20 years old is determined as 1.5 kg N / tree /year.

INFLUENCE OF FERTILIZATION ON GROWTH OF YOUNG CHESTNUT TREES (Castanea sativa MILL.) MANAGED FOR WOOD PRODUCTION

ABSTRACT In Portugal, chestnut wood demand has increased in the last decades. Since chestnut plantations are usually established in low fertility soils, addition of N, P and K as fertilizers usually have a benefic effect in increasing wood productivity. The study aims to evaluate the effects of fertilization on growth of chestnut tree (Castanea sativa Mill.) cultivated for wood purposes. An experimental essay was established in a 3-year old chestnut tree stand with a planting spacing of 3.5 × 3.0 m. Four treatments were applied to randomized blocks with three repetitions: control (C), addition of phosphorus (P), addition of phosphorus and potassium (PK) and addition of nitrogen, phosphorus, and potassium (NPK). The chemical properties of the soil and the concentration of nutrients in the leaves were evaluated after the treatment, and measurements of tree diameter and stem height were made for a monitoring period of 4 years. Treatments did not affect soil properties or leaf nutrient concentrations. On the counterpart, the effect of the fertilizers was noticed for tree dimensions and growth. Gains of NPK in relation to the control were observed for the height variable, over the years. Seven years after application of the treatments, differences were also noticed for the diameter and the volume index variables. The NPK treatment has presented a significant effect on tree growth compared to the control, with noticeable gains in the stem height.

Eastern chestnuts nuts — dangerous chestnut pest

Goal. Determine the main ways of entry into the country of the dangerous quarantine type of eastern chestnut walnut-fruit (Asian chestnut gall Trach).
 Methods. Analytical informational messages of the European and Mediterranean Plant Protection Organization (EPPO), as well as data of EU phytosanitary services, literature and Internet resources.
 Results. Information is given on the new economically important species of Dryocosmus kuriphilus Yas., which is rapidly spreading in the countries of Europe. In Ukraine, the eastern chestnut nut walnut has a quarantine status. The threat of entering the species Dryocosmus kuriphilus with planting material (seedlings) of certain types of chestnuts from European countries in Ukraine exists. The absence of natural enemies contributes to the active resettlement of the pest. The focus should be on the study of the entomophages of the walnutworm. It is known that in Japan it is found in 26 species of parasitoids that control reproduction, in China — 11, in Korea and Italy — 15 species. The rapid spread of the pest in the EU is of great concern to scientists. The lack of natural enemies, as well as effective drugs approved for use, threaten the disappearance of chestnut plantations. The experience of some European countries shows that it effectively regulates the number of its specialized Torymus sinensis parasitoids, which was introduced into Europe from China and Japan.
 Conclusions There is a danger of entering into Ukraine the species Dryocosmus kuriphilus, which has quarantine status and is a threat to chestnut plantations.

Conversion of Secondary Forests into Chestnut Forests Affects Soil Nutrients in Anji County, China

The maintenance of drinking water safety is a major environmental issue. It is necessary to strengthen environmental protection in water source areas and establish good vegetation coverage. This study examined the effects of secondary forests transformation on chestnut forests on soil nutrient changes in the Fuji Reservoir, Anji County, Zhejiang province, China. Plots were set up in a chestnut plantation and a nearby secondary forest to measure the nutrient contents of soil samples that were collected from different soil depths. Differences of soil nutrient content from the two stands were significant at 0–20 cm soil depth. There were no significant differences in the contents of total phosphorus and total potassium between the two forests; however, the available phosphorus content in chestnut stands was 2.73 mg/kg higher than in secondary forests. Overall, the soil nutrient contents under chestnut stands were lower than those under secondary forests. Some of the soil surface is exposed due to the low diversity of the chestnut forest. The soil nutrients in the chestnut forest are usually carried and transferred in soil particle form and they become dissolved in the runoff during rainfall and lost, which explains the lower soil nutrient contents in the chestnut forest than the secondary forest. Therefore, for economic forests, such as chestnut forests, measures should be taken to protect understory vegetation and enhance soil and water conservation capacity, which is conducive to retaining soil nutrients.

UAV-Based Automatic Detection and Monitoring of Chestnut Trees

Unmanned aerial vehicles have become a popular remote sensing platform for agricultural applications, with an emphasis on crop monitoring. Although there are several methods to detect vegetation through aerial imagery, these remain dependent of manual extraction of vegetation parameters. This article presents an automatic method that allows for individual tree detection and multi-temporal analysis, which is crucial in the detection of missing and new trees and monitoring their health conditions over time. The proposed method is based on the computation of vegetation indices (VIs), while using visible (RGB) and near-infrared (NIR) domain combination bands combined with the canopy height model. An overall segmentation accuracy above 95% was reached, even when RGB-based VIs were used. The proposed method is divided in three major steps: (1) segmentation and first clustering; (2) cluster isolation; and (3) feature extraction. This approach was applied to several chestnut plantations and some parameters—such as the number of trees present in a plantation (accuracy above 97%), the canopy coverage (93% to 99% accuracy), the tree height (RMSE of 0.33 m and R2 = 0.86), and the crown diameter (RMSE of 0.44 m and R2 = 0.96)—were automatically extracted. Therefore, by enabling the substitution of time-consuming and costly field campaigns, the proposed method represents a good contribution in managing chestnut plantations in a quicker and more sustainable way.

Responses of soil greenhouse gas emissions to different application rates of biochar in a subtropical Chinese chestnut plantation

Biochar application has been proposed as an effective measure to mitigate greenhouse gas (GHG) emissions from soil. However, the effects of different biochar application rates on soil GHG emissions and their linkages with biochar-induced changes in soil environmental factors remain unclear in managed plantations. This study examined the responses of soil GHG emissions to different application rates of bamboo leaf biochar in a Chinese chestnut plantation. A two-year field trial was conducted to determine the changes in soil GHG emissions and key soil properties over time in B0 (control), B2, B5 and B10 treatments, representing biochar application rates of 0, 2, 5 and 10 t ha−1, respectively. Biochar application significantly (P < 0.05) decreased soil N2O emissions (from 2.60 to 2.11 t ha−1 yr−1) and increased soil CH4 uptake (from 3.13 to 4.22 t ha−1 yr−1), but did not change soil CO2 emissions. The biochar inhibition effect on soil GHG emissions increased with increasing biochar application rates, with greater inhibition in the first year than in the second year. Biochar application also decreased the concentrations of soil NH4+-N, NO3–-N and water-soluble organic N (WSON), but increased the concentrations of water-soluble organic C (WSOC) and microbial biomass C (MBC). Regardless of the treatments, the soil GHG emissions were significantly (P < 0.01) correlated with soil temperature, but not with soil moisture content. Soil CO2 and N2O emissions, and soil CH4 uptake were positively (P < 0.05) correlated with WSOC concentration under the B0, B2 and B5 treatments only. A significant relationship (P < 0.05) was observed between soil MBC and soil CO2 emissions (only for the B0 and B2 treatments), and soil MBC and soil N2O emissions (only for the B0, B2 and B10 treatments). The results suggest that biochar application rates can alter the relationships between GHG emissions and soil WSOC and MBC concentrations. The soil N2O emissions were positively (P < 0.05) correlated with the NH4+-N, NO3−-N and WSON concentrations in all treatments. This study demonstrated that the management practice (i.e. biochar application to soil) decreased soil GHG emissions in a Chinese chestnut plantation via changes in key soil properties, with implications for the mitigation of soil GHG emissions in subtropical plantations.

Türkiye Kestane Piyasasındaki Gelişmeler

Turkey is one of the main countries both in producing and exporting chestnut in the world. Objective of this study was to evaluate the structure and developments in the chestnut market of Turkey since the 1960s. The main data were gathered from the databases of the Food and Agriculture Organization and the Turkish Statistical Institute. In 2016, Turkey was the second largest chestnut producer in the world with a share of 2.97%. Chestnut plantation areas in Turkey have decreased from 48,000 to 39,000 ha since 1961. While chestnut production increased to 90,000 tons in 1988, and decreased to 65,000 t recently. Whereas the yield per hectare was over 2 t in 1988, which decreased to 1.6 t recently, due to ink disease and canker blight. Most of the chestnut production is traditionally sold by producers to wholesalers; therefore, producers cannot compete with wholesalers due to lack of sufficient and effective cooperation under farmer organization. Whereas there isn’t any government intervention to the domestic chestnut markets in Turkey. It is implemented 43,2% of tariff rate was implemented for chestnut in importation. Although the net incomes per ton of the chestnut producers have increased from 1,000 US$ to 3,500 US$ since 2001, total and per capita chestnut consumption amounts have decreased since the late 1980s. Turkey’s chestnut export fluctuated between 1,000 t and 12,000 t depending on production and price levels and it accounted for 4.1% of the global chestnut exportation. In recent years, Turkey has imported between 20 t and 700 t chestnut totaling of 5,000-700,000 US$ in value.

First Report of Ectomycorrhizal Fungus, Laccaria ochropurpurea, Associated with Castanea dentata (American Chestnut) Roots in a Mixed-Species Plantation

American chestnut (Castanea dentata) is critically endangered by chestnut blight caused by Cryphonectria parasitica. Beneficial interactions with mutualistic ectomycorrhizae sometimes confer resistance to pathogens; however, little is known about the mycorrhizal partners of American chestnut. Basidiocarps of Laccaria ochropurpurea were observed in a 10-year-old American chestnut plantation. The identity of the species was confirmed utilizing the nuclear ribosomal internal transcribed spacer. In spring 2018, root fragments were excised from beneath three American chestnut trees in three separate plots where basidiocarps were observed. Root tips with evidence of mycorrhizal fungal colonization were pooled, extracted, and sequenced to confirm both the plant host and mycorrhizal associates. To our knowledge, this is the first direct confirmation of American chestnut roots associated with L. ochropurpurea. We suggest further studies to investigate whether this association is common, whether it confers any disease resistance, and if this mutualistic association could be employed in restoration efforts of the American chestnut.