Arbutus unedo L. (strawberry tree, Ericaceae) is a woody species with a circum-Mediterranean distribution. It has considerable ecological relevance in southern European forests due to its resilience to abiotic and biotic stressors. Its edible red berries are used in the production of traditional products, including an expensive spirit. Several compounds extracted from the species have bioactive properties used by the cosmetic and pharmaceutical industries. The strawberry tree has gone from a neglected species to become a highly valuable crop with large cultivated areas in southern European and North African countries. Due to an increasing demand from farmers for plants with improved features, researchers have been trying to improve this species through conventional and biotechnological tools, focusing mainly on population analysis using molecular markers, in vitro cloning, tolerance to biotic and abiotic stresses, and intraspecific crosses to obtain genotypes with new characteristics. The objective of this review is to gather and update information about the species and make it available to researchers and stakeholders. Future research areas that are considered a priority for this species are highlighted.

Tree diversity has long been considered a key driver of insect herbivory in forest ecosystems. However, studies have given contradictory results: increased tree diversity can have positive, negative or neutral effects on insect herbivory. Since many issues can complicate the tree-herbivore interactions, the descriptor ‘tree diversity’ per se actually has only limited explanatory power for insect herbivory. Particularly, in addition to the direct bottom-up effects on insect herbivores, tree diversity may have stronger indirect top-down effects via natural enemies of insect herbivores. However, most research has addressed only direct bottom-up impacts. In fact, insect herbivory is the result of complex interactions (food webs) among all the species in a community. Although it is hard to integrate all functionally important species and dynamic information into food webs, the effects of tree diversity on insect herbivory are highly dependent on the dominant species at different trophic levels. It is important and practical to simultaneously consider the characteristics of main trees, herbivores, and natural enemies when attempting to predict the overall effects of forest tree diversity on insect herbivory. In order to ensure comparability between studies, it is necessary to classify them according to the descriptors of insect herbivory and tree diversity, and to compare results within each category. These measures might enhance our understanding of the mechanisms by which tree diversity drives insect herbivory and, in turn, help to develop sustainable pest management strategies for forests.

Ground-level ozone (O₃) is a widespread air pollutant causing extensive injuries in plants. However, its effects on perennial energy crops remain poorly understood due to technical difficulties in cultivating fast-growing shrubs for biomass production under O₃ treatment on the field. Here we present the results of a two-year evaluation in the framework of which willow (Salix sachalinensis F. Schmid) shrubs were exposed to ambient (AOZ) or elevated (EOZ) O₃ in two successive growing seasons (2014, 2015) and treated with 0 (EDU0) or 400 mg L⁻¹ (EDU400) ethylenediurea spray in the second growing season. In 2014, EOZ altered the chemical composition of both top young and fallen leaves, and a novel mechanism of decreasing Mg in fallen leaves while highly enriching it in young top leaves was revealed in shrubs exposed to EOZ. In 2015, EDU400 alleviated EOZ-induced decreases in leaf fresh mass to dry mass ratio (FM/DM) and leaf mass per area (LMA). While EDU400 protected against EOZ-induced suppression of the maximum rate at which leaves can fix carbon (A _max) in O₃-asymptomatic leaves, it did not alleviate EOZ-induced suppression of the maximum rates of carboxylation (V _Cmax) and electron transport (J _max) and chlorophylls a, b, and a +  b in the same type of leaves. In O₃-symptomatic leaves, however, EDU400 alleviated EOZ-induced suppression of chlorophylls a and a +  b, indicating different mode of action of EDU between O₃-asymptomatic and O₃-symptomatic leaves. Extensive herbivory occurred only in AOZ-exposed plants, leading to suppressed biomass production, while EOZ also led to a similar suppression of biomass production (EDU0 × EOZ vs. EDU400 × EOZ). In 2016, carry-over effects were also evaluated following cropping and transplantation into new ambient plots. Effects of EOZ in the preceding growing seasons extended to the third growing season in the form of suppressed ratoon biomass production, indicating carry-over effect of EOZ. Although EDU400 protected against EOZ-induced suppression of biomass production when applied in 2015, there was no carry-over effect of EDU in the absence of EDU treatment in 2016. The results of this study provide novel mechanistic understandings of O₃ and EDU modes of action and can enlighten cultivation of willow as energy crop.

Slash pine (Pinus elliottii Engelm. var. elliottii) is a resin-producing species grown worldwide for significant economic benefits for wood production. Resin tapping creates a carbon sink at the expense of carbon allocation for growth and consequently, wood production may be reduced. Non-structural carbohydrates comprising starch and sugars stored in plant organs, may serve as intermediate pools between assimilation and utilisation. However, the effect of resin tapping between tree growth and non-structural carbohydrates is not well understood. This study investigated (1) the effects of resin tapping on radial growth, (2) the effects of resin tapping on non-structural carbohydrate pools in different compartments, and (3) the feasibility of resin production without disruption of tree growth. Twenty one-year-old slash pines were subjected to resin tapping over two successive years. Non-structural carbohydrate concentrations in needles, branches, stem phloem, and roots of tapped and untapped trees in summer and winter were determined after the second year of resin harvest. The results showed that tapping had no significant effects on annual increments. Starch was the dominant non-structural carbohydrate fraction, regardless of tissues and season, and constituted up to 99% of the total non-structural carbohydrates in the phloem and roots. Glucose and fructose were the dominant sugars; sucrose was negligible. Compared with the controls, tapped trees showed 26% lower non-structural carbohydrate concentration in the phloem above the tapping wound in summer, which was attributable to the decreased abundance of starch, glucose, fructose, and sucrose. In winter, the altered non-structural carbohydrate profiles in the phloem above the tapping wounding were minimised as a result of recovery of the sugar concentrations. In contrast to free sugars, which accumulated substantially in needles and branches during winter, starch was enriched in the phloem, roots, and current-year needles. The results provide evidence for a localised effect of resin tapping, and highlight the observation that resin extraction does not always cause a sacrifice in wood growth under a moderate resin-tapping intensity in slash pine plantations.

The breaking of dormancy mediated by reactive nitrogen species (RNS) is related to the accumulation of reactive oxygen species (ROS) in germinating embryos but the underlying mechanism is unclear. The objectives of this study were: (1) to explore the relationship between RNS-mediated dormancy release and ROS accumulation in germinating embryos of Sorbus pohuashanensis; and, (2) to investigate the relationships among germination time, ROS metabolism, and endogenous hormone synthesis. We studied the effects of exogenous nitric oxide (NO) donor sodium nitroprusside (SNP), the NO scavenger (4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), abscisic acid (ABA), the exogenous ethylene donor ethrel, and the ethylene receptor inhibitor 2,5-norbornadien (NBD) on embryo germination and seedling growth. Embryos were released from dormancy by pretreatment with NO or ethylene, which was related to increased ethylene biosynthesis and decreased ABA levels. Breaking of dormancy by SNP was related to increased levels of ethylene, hydrogen peroxide, and glutathione, increased activities of superoxide dismutase and glutathione peroxidase, and decreased levels of ABA, superoxide anions, and malondialdehyde. These effects of nitric oxide were especially significant in seedling hypocotyls and radicles. These results demonstrate that NO can break S. pohuashanensis embryo dormancy by inducing ethylene biosynthesis, and that this signalling pathway is closely related to ROS accumulation and the antioxidant defence response.

To determine the optimal embryogenic capacity (somatic embryo production) of the selected elite nematode-resistant genotypes of Pinus thunbergii, variables such as embryogenic tissue (ET) morphology, maternal genotype, proliferation rate and tissue age were analyzed. ET morphology and histological evaluation of the proliferation stage showed a decrease in filamentous clump and protuberant surfaces and a decline in the acetocarmine-staining area, which indicates a decrease in somatic embryo production (SEP). Variations in cell physiology during the proliferation stage showed that SEP was positively correlated with soluble sugars and proteins, but negatively correlated with starch, peroxidase, and superoxidase. In addition, SEP was significantly (p < 0.001) affected by maternal genotype, tissue age and proliferation rate. Moreover, SEP was positively correlated with proliferation rate (r = 0.98, p < 0.001), but negatively correlated with tissue age (r =  − 0.95, p < 0.001). In general, the results suggest that SEP could be assessed in ET proliferation stages by the apparent cell morphology, histology, proliferation rate and tissue age, which provides novel insights for evaluating the ET maturation capacity (number of somatic embryos) during the proliferation stage of P. thunbergii somatic embryogenesis.

Apuleia leiocarpa is an environmentally and economically significant Atlantic Forest species threatened by ongoing exploitation. The vegetative propagation of the species could be a step forward to enable implantation of clonal seed orchards and multiplication of selected trees but remains unknown to date. This study assessed the mini-cutting technique for propagation of A. leiocarpa and determined the time required for rooting and viable mini-cutting type and sizes. The results show that it is possible to propagate A. leiocarpa with mini-cuttings derived from mini-stumps produced with seeds; the mini-stumps presented regrowth capacity and remained constantly productive for 1 year; 10-cm A. leiocarpa mini-cuttings should remain under misting conditions for at least 40 days, and the vegetative propagation of A. leiocarpa with intermediate 7- to 10-cm mini-cuttings resulted in more vigorous clonal seedlings than smaller mini-cuttings.

Branch phenotypic traits determine tree crown architecture, which in turn governs leaf display, light interception, and biomass production. Sylleptic and proleptic branches are the obviously different branch phenotypes in the poplar crown. Many studies have focused on the influence of sylleptic branch numbers (SBN) on biomass production, but the research on the influence of proleptic branch phenotypes was only a few. To explore the relationship between proleptic branch traits and biomass generation production in a high-density poplar plantation, we investigated the branch phenotypic traits of three poplar genotypes, all of which have high survival rates in forests (> 95%) and significantly different crown architecture and biomass performance in the high-density plantations (1667 stems ha⁻¹). The plantation site was established in 2007. A terrestrial laser scanner was used to measure branch characteristics such as length, angle of origin and termination, and azimuth angle. A hierarchical cluster analysis performed on branch characteristics showed that SBN, crown depth, and proleptic branch curvature (PBC) were clustered with biomass production and leaf area index (LAI). Among all of the monitored traits, PBC played the second most important role in biomass production after SBN and was significantly correlated with SBN, LAI, and biomass production. The positive correlation between PBC and SBN indicated that a larger PBC was associated with more sylleptic branches within the monitored genotypes planted in the high-density plantation, providing greater leaf area and biomass production. The results of this study will improve the identification of high-production poplar varieties for cultivation in high-density plantations for biofuel production.

With changes in global climate and land use, the area of desertified farmland in southeastern Horqin Sandy Land (HSL) has increased in recent years, and farmlands are being abandoned. These abandoned farmlands (AFs) negatively impact the local ecology. Therefore, the aim of the present study was to select suitable trees and shrubs for those AFs to prevent and control the desertification tendency. In this study, three AFs were fenced for 2 years, then 37 arbor and shrub species or varieties of 21 families were planted in the fenced AFs and grown for 10 years. The ecological adaptability of the species was evaluated and ranked using a principal component analysis. The results showed that the biodiversity of the AFs significantly improved after 2 years of fencing; the Shannon–Wiener index and species richness of perennial grasses and forbs were 1.45 and 3.6 times higher, respectively, than for the unfenced AF. Among all species planted in fenced AFs, nine tree species had positive comprehensive F (CF) values; Pinus sylvestris (Russian Shira steppe provenance), Populus alba ‘Berolinensis’ and Gleditsia triacanthos had CF greater than 1, and the first (PC1), second (PC2) and third (PC3) principal component values (F ₁, F ₂, F ₃) were all positive. Among the shrubs, only Lespedeza bicolor and Rosa xanthina f. normalis had CF greater than 0. All these results suggest that fencing improves biodiversity and that planting trees and shrubs that have higher CF values on the basis of fencing is an effective way to green and beautify AFs in HSL.

Litter production and decomposition are critical to forest productivity, nutrient cycling, and carbon sequestration in tropical woody ecosystems. However, nutrient release and leaf litter stoichiometry in tropical legume tree plantations over the long term after outplanting are poorly understood or even unknown. Toward improving our understanding of the pattern of changes in the decomposition of N-fixing leaf litters and their possible impact on carbon storage, we measured litter production, mass loss and nutrient release for 240 d during litter decomposition for two tropical legume tree species (Plathymenia reticulata and Hymenaea courbaril), in Rio de Janeiro, Brazil. Litter production for P. reticulata was 5.689 kg ha⁻¹ a⁻¹ and 3.231 kg ha⁻¹ a⁻¹ for H. courbaril. The patterns of mass loss rates were similar; however, nutrient release was greater for P. reticulata, while H. courbaril showed immobilization of nutrients, especially for N, which increased by almost 20% in the early phase of decomposition followed by gradual release. Litter from the N-fixing species did differ in nutrient chemistries over time, which was not surprising given that initial nutrient concentrations varied broadly, except for C and P. Most of the nutrient concentrations increased as the remaining litter mass decreased in both species, except for C and K. The C:N and N:P ratios differed between the species, but N:P did not correlate to mass loss. Both species had N-rich leaves, but P. reticulata decomposition was very likely P-limited, while H. courbaril seemed to be co-limited by N and P. The results showed different patterns in nutrient release and the stoichiometry involved in the decomposition dynamics of the two tropical N-fixing species, even though they have similar litter decay rates. Both species, but especially P. reticulata, may help re-establish nutrient cycling in disturbed ecosystems.

The relationships between climate conditions and wood density in tropical forests are still poorly understood. To quantify spatial dependence of wood density in the state of Minas Gerais (MG, Brazil), map spatial distribution of density, and correlate density with climate variables, we extracted data from the Forest Inventory of Minas Gerais for 1988 trees scaled throughout the territory and measured wood density of discs removed from the trees. Environmental variables were extracted from the database of the Ecological-Economic Zoning of Minas Gerais. For spatial analysis, tree densities were measured at 44 georeferenced sampling points. The data were subjected to exploratory analysis, variography, cross-validation, model selection, and ordinary kriging. The relationships between wood density and environmental variables were calculated using dispersion matrices, linear correlation, and regression. Wood density proved to be highly spatially dependent, reaching a correlation of 96%, and was highly continuous over a distance of 228 km. The distribution of wood density followed a continuous gradient of 514–659 kg m⁻³, enabling correlation with environment variables. Density was correlated with mean annual precipitation (− 0.57), temperature (0.63), and evapotranspiration (0.83). Geostatistical methods proved useful in predicting wood density in native tropical forests with different climate conditions. Our results confirmed the sensitivity of wood density to climate change, which could affect future carbon stock in forests.

Grazing significantly affects the distribution, growth, and productivity of shrubs. In this study, we evaluated the effects of grazing disturbance on the spatial distribution patterns and interspecific relationships of two desert shrubs, Ammopiptanthus mongolicus and Sarcozygium xanthoxylon. Three types of grazing conditions were considered, including enclosed area (EA), seasonal rotational grazing area (SRGA), and grazing area (GA) (100 m × 100 m), in the West Ordos Nature Reserve of Inner Mongolia, China. The results showed that A. mongolicus and S. xanthoxylon populations were uniformly distributed at a small scale, and the distribution in EA and SRGA became gradually random. In GA, A. mongolicus population showed aggregated distribution but S. xanthoxylon population showed random distribution at a small scale. Moreover, both A. mongolicus and S. xanthoxylon populations at the 5–7 m scale showed random distribution. At the small and intermediate scales, the two species showed positive interspecific relationships of GA. However, no interspecific relationship was noted between the two species in EA and SRGA. A significant positive relationship (P < 0.01) was noted between the two species at 2–9 m and a negative relationship (P < 0.01) at 13–17 m scales in GA. Positive relationship (P < 0.01) was noted between the two species at 6–13 m scales and a significant negative relationship (P < 0.01) at 14–24 m scales in SRGA. The two species of desert shrubs showed positive interspecific relationships at the small scale, and they showed negative relationships as the interspecific competition intensified in the presence of grazing disturbance. When the grazing intensity exceeds a certain threshold, the interspecific relationships become weak. Therefore, moderate grazing would facilitate interspecific competition and species succession, whereas excessive grazing would disrupt natural competition causing desertification ultimately.

The characteristics of soil holding capacity for different shrub-grass patterns are important to research the mechanisms regulating vegetation on slopes. The objective of this study was to describe the characteristics and mechanisms of soil erosion and hydraulic parameters under different vegetation patterns in the Pisha sandstone area of Inner Mongolia on lands of 8° slope gradient. We carried out field scouring experiments on five different shrub-grass patterns as treatments, viz no shrubs (GL), shrubs on the upper part of the slope (SU), middle part of the slope (SM) and lower part of the slope (SL). We designated bare slope (BL) as the control. We employed three different water flow rates (15, 20, 30 L·min⁻¹). Our results showed that the contribution of plant root systems to slope sediment reduction ranged from 64 to 84%. The root systems proved to be the main contributing factor to reduction of erosion by vegetation. The relationship between soil detachment rate, stream flow power, and flow unit stream power under different scouring discharge rates showed that soil detachment declined in rank order as: BL > GL > SU > SM > SL. The SL pattern had the lowest soil detachment rate (0.098 g·m⁻²·s⁻¹), flow stream power (2.371 W·m⁻²), flow unit stream power (0.165 m·s⁻¹) and flow shear stress (16.986 Pa), and proved to be the best erosion combating pattern. The results of decision coefficient and path analysis showed that stream power was the most important hydraulic parameter for describing soil detachment rate. The combination of stream power and shear stress, namely Dr = 0.1ω − 0.03τ − 0.56 (R² = 0.924), most accurately simulated the soil detachment characteristics on slopes. Our study suggests that the risk of soil erosion can be reduced by planting shrub-grass mixes on these slopes. Under the conditions of limited water resources and economy, the benefit of sediment reduction can be maximized by planting shrubbery on the lower parts of slopes.

Understanding the interaction between canopy structure and the parameters of interception loss is essential in predicting the variations in partitioning rainfall and water resources as affected by changes in canopy structure and in implementing water-based management in semiarid forest plantations. In this study, seasonal variations in rainfall interception loss and canopy storage capacity as driven by canopy structure were predicted and the linkages were tested using seasonal filed measurements. The study was conducted in nine 50 m × 50 m Robinia pseudoacacia plots in the semiarid region of China’s Loess Plateau. Gross rainfall, throughfall and stemflow were measured in seasons with and without leaves in 2015 and 2016. Results show that measured average interception loss for the nine plots were 17.9% and 9.4% of gross rainfall during periods with leaves (the growing season) and without leaves, respectively. Average canopy storage capacity estimated using an indirect method was 1.3 mm in the growing season and 0.2 mm in the leafless season. Correlations of relative interception loss and canopy storage capacity to canopy variables were highest for leaf/wood area index (LAI/WAI) and canopy cover, followed by bark area, basal area, tree height and stand density. Combined canopy cover, leaf/wood area index and bark area multiple regression models of interception loss and canopy storage capacity were established for the growing season and in the leafless season in 2015. It explained 97% and 96% of the variations in relative interception loss during seasons with and without leaves, respectively. It also explained 98% and 99% of the variations in canopy storage capacity during seasons with and without leaves, respectively. The empirical regression models were validated using field data collected in 2016. The models satisfactorily predicted relative interception loss and canopy storage capacity during seasons with and without leaves. This study provides greater understanding about the effects of changes in tree canopy structure (e.g., dieback or mortality) on hydrological processes.

Although forests play important roles in the hydrological cycle, there is little information that relates the water retention capacity of litter in areas under passive restoration, especially in Cerrado savannas. This study relates litter levels to water holding capacity and effective water retention among forest fragments under different passive restoration stages: 46, 11, and 8 years to better understand litter hydrological functions in the Cerrado. Water retention capacity and effective water retention capacity of litters (unstructured materials, branches and leaves) in the field were monitored on a monthly basis. Total litter accumulation at 46 years was significantly higher than that of the other succession stages. Unstructured litter mass was significantly higher than that of leaves and branches. The 46-year stage had the highest water holding capacity in the leaf fraction, followed by unstructured material and branches. Although the water holding capacity was lower in the oldest restoration, this site showed the highest efficiency under field conditions. The process was quickly reestablished, as the 11-year restoration showed results closer to that for the 46-year stage in comparison to the area at 8 years. Thus, passive restoration plays a key role in soil water maintenance due to the influence of litter in Cerrado savannas. Deforestation and the imminent need of restoring degraded sites, highlight the need for further studies focused on better understanding of the process of forest restoration and its temporal effect on soil water recovery dynamics.

Wildfire risk related to hazards on people and assets is expected to increase in the face of climate change, especially in fire-prone environments such as the Mediterranean Basin. Distinguishing rationalities, i.e., the complex profile of multi-thematic, wildfire-related perceptions that collectively characterize and quantify all of a society’s responses, its interrelations, and influence on its insights, are of primary importance to understand the degree of preparedness and the direction that wildfire management policies are moving. Greece is a country that suffered mega-wildfire events during the first years of the twenty-first century. This paper presents a scheme of advanced multivariate statistical procedures applied on standard social survey questionnaires to uncover different or similar rationalities between fire management services and the general public. Profession-centered versus message-oriented rationalities is defined. They differ mainly on the priorities attributed to strengthening personnel and equipment capacities versus the need for public education and awareness. Both are evaluated against the needs of long-term risk assessment and forest management policies in Greece. The main conclusion is that Greek society, although traumatized by recent fire disasters, is not yet prepared for long-term strategic forestry adaptation and planning.

In forest growing at any one site, the growth rate of an individual tree is determined principally by its size, which reflects its metabolic capacity, and by competition from neighboring trees. Competitive effects of a tree may be proportional to its size; such competition is termed ‘symmetric’ and generally involves competition below ground for nutrients and water from the soil. Competition may also be ‘asymmetric’, where its effects are disproportionate to the size of the tree; this generally involves competition above ground for sunlight, when larger trees shade smaller, but the reverse cannot occur. This work examines three model systems often seen as exemplars relating individual tree growth rates to tree size and both competitive processes. Data of tree stem basal area growth rates in plots of even-aged, monoculture forest of blackbutt (Eucalyptus pilularis Smith) growing in sub-tropical eastern Australia were used to test these systems. It was found that none could distinguish between size and competitive effects at any time in any one stand and, thus, allow quantification of the contribution of each to explaining tree growth rates. They were prevented from doing so both by collinearity between the terms used to describe each of the effects and technical problems involved in the use of nonlinear least-squares regression to fit the models to any one data set. It is concluded that quite new approaches need to be devised if the effects on tree growth of tree size and competitive processes are to be quantified and modelled successfully.

Plant recognition has great potential in forestry research and management. A new method combined back propagation neural network and radial basis function neural network to identify tree species using a few features and samples. The process was carried out in three steps: image pretreatment, feature extraction, and leaf recognition. In the image pretreatment processing, an image segmentation method based on hue, saturation and value color space and connected component labeling was presented, which can obtain the complete leaf image without veins and background. The BP-RBF hybrid neural network was used to test the influence of shape and texture on species recognition. The recognition accuracy of different classifiers was used to compare classification performance. The accuracy of the BP-RBF hybrid neural network using nine dimensional features was 96.2%, highest among all the classifiers.

In forest modeling to estimate the volume of wood, artificial intelligence has been shown to be quite efficient, especially using artificial neural networks (ANNs). Here we tested whether diameter at breast height (DBH) and the total plant height (Ht) of eucalyptus can be predicted at the stand level using spectral bands measured by an unmanned aerial vehicle (UAV) multispectral sensor and vegetation indices. To do so, using the data obtained by the UAV as input variables, we tested different configurations (number of hidden layers and number of neurons in each layer) of ANNs for predicting DBH and Ht at stand level for different Eucalyptus species. The experimental design was randomized blocks with four replicates, with 20 trees in each experimental plot. The treatments comprised five Eucalyptus species (E. camaldulensis, E. uroplylla, E. saligna, E. grandis, and E. urograndis) and Corymbria citriodora. DBH and Ht for each plot at the stand level were measured seven times in separate overflights by the UAV, so that the multispectral sensor could obtain spectral bands to calculate vegetation indices (VIs). ANNs were then constructed using spectral bands and VIs as input layers, in addition to the categorical variable (species), to predict DBH and Ht at the stand level simultaneously. This report represents one of the first applications of high-throughput phenotyping for plant size traits in Eucalyptus species. In general, ANNs containing three hidden layers gave better statistical performance (higher estimated r, lower estimated root mean squared error–RMSE) due to their greater capacity for self-learning. Among these ANNs, the best contained eight neurons in the first layer, seven in the second, and five in the third (8 − 7 − 5). The results reported here reveal the potential of using the generated models to perform accurate forest inventories based on spectral bands and VIs obtained with a UAV multispectral sensor and ANNs, reducing labor and time.

The NAC transcription factor family is plant-specific with various biological functions. However, there are few studies on the NAC gene involving coniferous species. Bioinformatics research and expression analysis of NAC genes in Larix olgensis can be used to analyse the function of the NAC gene in the future. Screening of excellent genetic materials and molecular breeding have been utilized to cultivate high-quality, stress-resistant larches. According to the transcriptome data for L. olgensis, the genes Unigene81490 and Unigene70699 with complete ORFs (open reading frames) were obtained by conserved domain analysis and named LoNAC1 and LoNAC2, respectively. The cDNAs of LoNAC1 and LoNAC2 were 1971 bp and 1095 bp in length, encoding 656 and 364 amino acids, respectively. The molecular weights of the proteins encoded by the two genes were predicted to be 72.61 kDa and 41.13 kDa, and subcellular localization analysis indicated that the proteins were concentrated in the nucleus. The results of real-time quantitative PCR analysis showed that at different growth stages and in different tissues of L. olgensis, the relative expression levels of the two NAC genes were highest in the stem, and the expression differences were more obvious in non-lignified tissues. After drought, salt and alkali stress and hormone treatment, expression was induced to different degrees. The expression levels of LoNAC1 and LoNAC2 in semi-lignified L. olgensis were higher than in the other two periods (non-lignified and lignified), and expression levels significantly increased under drought and salt stress. Relative expression levels changed under hormone treatment. It is speculated that these two genes may not only be related to drought and salt stress and secondary growth but may also be induced by hormones such as abscisic acid. Overall, LoNAC1 and LoNAC2 are genetic materials that can be used for molecular breeding of larch.

Robinia pseudoacacia is an important afforestation tree introduced to China in 1878. In the present study, we examined the genetic diversity among 687 strains representing four improved varieties and two secondary provenances, comprising 641 clones and 46 seedlings. Ninety-one simple sequence repeats (SSRs) were selected through segregation analysis and polymorphism characterization, and all sampled individuals were genotyped using well-characterized SSR markers. After excluding loci with non-neutral equilibrium, missing locus data and null alleles, we used 36 primer pairs to assess the genetic diversity of these germplasm resources, revealing vast genetic differentiation among the samples, with an average of 8.352 alleles per locus and a mean Shannon′s index of 1.302. At the population level, the partitioning of variability was assessed using analysis of molecular variance, which revealed 93% and 7% variation within and among collection sites, respectively. Four clusters were detected using structure analysis, indicating a degree of genetic differentiation among the six populations. Insights into the genetic diversity and structure of R. pseudoacacia provide a theoretical basis for the conservation, breeding and sustainable development in China.

Forests in Northeast China in the Greater and Lesser Khingan Mountains (GKM and LKM) account for nearly 1/3 of the total state-owned forests in the country. Regional and historical comparisons of forest plants and macrofungi will favor biological conservation, forest management and economic development. A total of 1067 sampling plots were surveyed on forest composition and structure, with a macrofungi survey at Liangshui and Huzhong Nature Reserves in the center of two regions. Regional and historical differences of these parameters were analyzed with a redundancy ordination of their complex associations. There were 61–76 families, 189–196 genera, and 369–384 species, which was only 1/3 of the historical records. The same dominant species were larch and birch with Korean pine (a climax species) less as expected from past surveys in the LKM. Shrub and herb species were different in the two regions, as expected from historical records. There was 10–50% lower species diversity (except for herb evenness), but 1.8- to 4-time higher macrofungi diversity in the GKM. Compared with the LKM, both tree heights and macrofungi density were higher. Nevertheless, current heights averaging 10 m are half of historical records (> 20 m in the 1960s). Edible macrofungi were the highest proportion in both regions, about twice that of other fungal groups, having important roles in the local economy. A major factor explaining plant diversity variations in both regions was herb cover, followed by shrubs in the GKM and herb-dominant species in the LKM. Factors responsible for macrofungi variations were tree density and shrub height. Vaccinium vitis-idaea and Larix gmelinii in the GKM but tree size and diversity were important factors in the LKM. Our findings highlighted large spatial and historical differences between the GKM and LKM in plant-macrofungal composition, forest structure, and their complex associations, which will favor precise conservation and management of forest resources in two region in the future.

Eucalyptus harvesting, forwarding and soil tillage operations are among the main causes for compaction of forest soils, with potential impacts on productivity. This concern is especially important in areas with soils that are naturally compacted (fragipans and duripans). In these soils, tillage operations include the use of subsoilers that can reach depths of more than one meter and require heavy tractors that exert high pressure on the soil. One of the ways to try to minimize the effect of this compaction is by retaining harvest residues. The objective of this study was to evaluate the impacts of eucalyptus harvesting on soil physical attributes, as well as to determine the potential of different types of residue management to reduce compaction from the soil tillage operation. Two experiments were conducted in the same area with a Yellow Argisol. In the first experiment, compaction caused by mechanized harvesting with harvester + forwarder was evaluated. In the second experiment, different managements of harvest residues were examined as potential modifiers of soil compaction during tillage for new plantings. For this, three managements systems were tested: (1) retention of all harvest residues and litter from the previous rotation (HR + L), (2) retention of litter from the previous rotation (L), and (3) removal of harvest residues and litter from the previous rotation (WR). Before and after harvest, sampling was carried out in the planting rows and inter-rows, and after tillage, samples were collected in the traffic line of the subsoiler-tractor set. In both experiments, undisturbed soil samples were collected from the center of the 0–10, 10–20, 20–40, 40–60, and 60–100 cm layers to determine soil density and total porosity. In each period and site of evaluation, mechanical resistance to penetration up to the 60-cm depth was also determined. The harvesting operation increased soil density at 0–10 and 60–100 cm depths only in the inter-rows. Retention of harvest residues and litter (HR + L) after harvesting avoided increases in soil density and penetration resistance caused by machine traffic during tillage. The results indicate the importance of retaining harvest residues on forest soils for achieving sustainable utilization and for conserving soil quality.

Soil respiration (R _s) is important for transporting or fixing carbon dioxide from the atmosphere, and even diminutive variations can profoundly influence the carbon cycle. However, the R _s dynamics in a loess alpine hilly region with representative sensitivity to climate change and fragile ecology remains poorly understood. This study investigated the correlation and degree of control between R _s and its photosynthetic and environmental factors in five subalpine forest cover types. We examined the correlations between R _s and variables temperature (T ₁₀) and soil moisture content at 10 cm depth (W ₁₀), net photosynthetic rate (P _n) and soil properties to establish multiple models, and the variables were measured for diurnal and monthly variations from September 2018 to August 2019. The results showed that soil physical factors are not the main drivers of R _s dynamics at the diel scale; however, the trend in the monthly variation in R _s was consistent with that of T ₁₀ and P _n. Further, R _s was significantly affected by pH, providing further evidence that coniferous forest leaves contribute to soil acidification, thus reducing R _s. Significant exponential and linear correlations were established between R _s and T ₁₀ and W ₁₀, respectively, and R _s was positively correlated with P _n. Accordingly, we established a two-factor model and a three-factor model, and the correlation coefficients (R ²) was improved to different degrees compared with models based only on T ₁₀ and W ₁₀. Moreover, temperature sensitivity (Q ₁₀) was the highest in the secondary forest and lowest in the Larix principis-rupprechtii forest. Our findings suggest that the control of R _s by the environment (moisture and temperature) and photosynthesis, which are interactive or complementary effects, may influence spatial and temporal homeostasis in the region and showed that the models appropriately described the dynamic variation in R _s and the carbon cycle in different forest covers. In addition, total phosphorus (TP) and total potassium (TK) significantly affected the dynamic changes in R _s. In summary, interannual and seasonal variations in forest R _s at multiple scales and the response forces of related ecophysiological factors, especially the interactive driving effects of soil temperature, soil moisture and photosynthesis, were clarified, thus representing an important step in predicting the impact of climate change and formulating forest carbon management policies.

Vegetation types alter soil ecosystems by changing soil fauna community activities and soil physical–chemical properties. However, it is unclear how tree species (natural forest, native and exotic tree plantations) promote changes in the soil ecosystem, and if these changes alter functional groups of soil fauna and ecosystem services. To determine the effects of five decades of old-field vegetation on soil ecosystems in the Brazilian Atlantic Forest, field sampling of three ecosystems (exotic tree species Pinus elliottii Engelm. plantation, endangered tree species Araucaria angustifolia (Bertol.) Kuntze plantation, and a natural ecosystem) were carried out, as well using bait-lamina tests and bioassays with collembolans, earthworms and seeds of Lactuca sativa L. Field sampling evaluated the soil fauna community and soil physical–chemical properties. The bait-lamina test in situ was carried out for 14-days to determine fauna feeding activity, and the bioassays evaluated the reproduction of Folsomia candida, the avoidance of Eisenia andrei, and germination of L. sativa in the soil from each ecosystem. The results are: (1) vegetation type altered the soil fauna community composition; (2) soil fauna feeding was reduced in the plantations compared to the natural ecosystem; (3) a physical barrier was created by recalcitrant litter that compromised fauna community structure and seed bank germination in situ; and, (4) changes in soil physical–chemical properties promoted decomposers.

Plagiodera versicolora Laicharting is a highly damaging leaf beetle foraging on willow leaves. In willow germplasm collections, observation has shown that Salix suchowensis Cheng was severely foraged by this leaf beetle while Salix triandra L. was damage free or only slightly damaged. Results of olfactometer bioassays show that the headspace volatiles from leaves of S. triandra significantly repelled adult beetles, suggesting that this species produces volatile repellents against P. versicolora. S. suchowensis had no effect on the beetles. Gas chromatography-mass spectrometry was carried out to profile the headspace volatile organic compounds and 23 compounds from leaves of the alternate species in significantly different concentrations were detected. The effects of 20 chemical analogs on host discrimination were examined. Olfactory response to these chemicals showed that o-cymene, a S. suchowensis specific constituent, significantly attracted adult P. versicolora. In contrast, cis-3-hexenyl acetate, a constituent concentrated more in S. triandra than in S. suchowensis, significantly repelled beetles. Mixing o-cymene and cis-3-hexenyl acetate in comparable concentrations as in the volatiles of S. suchowensis demonstrated that the latter could mask the attracting effect of the former, causing a neutral response by adult beetles to leaves of S. suchowensis against clean air. In addition, chemical analogs have the same effect as plants when resembling volatile organic compounds in real samples. Two volatile metabolites were detected triggering host discrimination by one of the most damaging insect pests to host and non-host willows. The two metabolites are of considerable potential for use as olfactory signs in managing the beetles.

Bursaphelenchus xylophilus, causal agent of pine wilt disease, causes extensive damage worldwide. Strategies are needed to inhibit population growth or block the spread of the invasive nematode to control pine wilt disease. The gene daf-8 plays crucial roles in larval development and dauer formation in Caenorhabditis elegans, but little is known about its orthologue in B. xylophilus. In the present molecular characterization and functional analysis of daf-8 in B. xylophilus (Bx-daf-8), RT-qPCR showed that the expression of Bx-daf-8 gradually increased during the embryonic stage, peaked in the second-stage juvenile (J2), then dramatically dropped in the J3, and remained at that low level for the rest of its life. Bx-daf-8-transgenic C. elegans was employed to mimic the spatiotemporal expression of Bx-daf-8, which was expressed close to the pharynx during early embryogenesis and weakly throughout the whole body during late embryogenesis. It was observed in head neurons and tail ganglions throughout all postembryonic stages. B. xylophilus embryos were severely abnormal, and hatching rate decreased sharply after Bx-daf-8 knockdown. daf-16-1 and da-f16-2, downstream genes in the IIS pathway, also dropped sharply after Bx-daf-8 knockdown. We propose that TGFβ may crosstalk with the IIS pathway upstream of Bx-daf-16 and that daf-8 may act as a master regulator of daf-16 in B. xylophilus. However, knockdown of Bx-daf-8 did not lead to constitutive developmental arrest at the dauer larval stage, indicating that dauer entry in B. xylophilus might be controlled by several genes and is more complicated than in C. elegans. Bx-daf-8 alone did not control the dauer entry in B. xylophilus, but it was indispensable for embryogenesis, providing a potential target for suppressing population growth of B. xylophilus.

Pine wilt disease caused by pine wood nematodes is a deadly disease of the genus Pinus requiring strong quarantine measures. Since its discovery, it has been widely distributed throughout the world. China is one of the countries with a severe rate of infections due to its abundant pine resources. In this study, nematode-trapping fungi were collected from pine trees in Ninghai City, Zhejiang Province, which is the key area of pine wilt control in February, May, September, October and November. The results showed that nematode- trapping fungi of pine are abundant, especially the number and species detected in each month and are quite different; species of fungi in July, September and November were more numerous and had higher separation rates. The dominant species in November was Arthrobotrys oligospora followed by Arthrobotrys cladodes; July and September it was A. cladodes. In each part of the tree, A. cladodes was the most widely distributed with a high separation rate. Therefore, it is the dominant fungal species in the area. Arboreal Bursaphelenchus xylophilus-trapping fungi are dependent on pine wood nematodes, and none were isolated from healthy pine trees. More arboreal B. xylophilus-trapping fungi were found under the bark than in the xylem. There is a close relationship between arboreal B. xylophilus-trapping fungi and pine wood nematodes. How to make use of these resources to reduce the damage of pine wood nematode fusarium is the focus of future research.

Wilt disease with unknown etiology causes mass mortality in commercial Acacia mangium nurseries in South Sumatra. This pathogen induces symptoms of chlorosis in the lower leaves and develops into the shoots; subsequently, the plants wither and die. This research identifies the pathogenic species causing this wilt disease and to assess its pathogenicity or virulence. Fifteen isolates of Fusarium oxysporum with varying colony sizes and color pigments were recovered from symptomatic A. mangium seedlings. The pathogenicity test showed that all isolates could infect plants with wilt severity reaching 80%, and the pathogen was verified as causing vascular disease. Koch’s postulate was verified by re-isolating the F. oxysporum isolates. The pathogen was confirmed by observing the morphological characters and elongation factor 1-α (tef1-α) gene sequences as F. oxysporum.

Düzlerçamı Wildlife Reserve Area (WRA) is the last natural habitat of fallow deer (Dama dama) in the world. Fallow deer is native to Turkey, however, its geographical range is currently confined to Düzlerçamı WRA, Antalya. To date, a detailed habitat investigation of fallow deer distribution has not been conducted. This study is vital for the last surviving populations of fallow deer in Turkey. Therefore, we studied the habitat suitability and utilization of fallow deer in the Düzlerçamı WRA. Vegetation and wildlife inventory was surveyed across a total of 304 sample areas between 2015 and 2017. Plant species were recorded according to the Braun-Blanquet method and wildlife surveys were based on footprints, feces, and other signs of fallow deer. Classification and regression tree techniques, as well as MAXENT, were used to model vegetation and fallow deer habitat. Topographic position index, terrain ruggedness index, roughness index, elevation, and bedrock formation were also calculated and included in the models. Based on our results, we drafted a habitat protection map for fallow deer. To ensure sustainability of habitats where populations of fallow deer are found in Turkey, we developed recommendations such as closuring human access of the 1st-degree Protection Area and reintroduction of the species to other potential habitats.