Shelford's law of tolerance is illustrated by a bell-shaped curve depicting the relationship between environmental factor/factors’ intensity and its favorability for species or populations. It is a fundamental basis of ecology when considering the regularities of environment impacts on living systems, and applies in plant biology, agriculture and forestry to manage resistance to environmental limiting factors and to enhance productivity. In recent years, the concept of hormesis has been increasingly used to study the dose–response relationships in living organisms of different complexities, including plants. This requires the need for an analysis of the relationships between the hormetic dose–response model and the classical understanding of plant reactions to environments in terms of Shelford's law of tolerance. This paper analyses various dimensions of the relationships between the hormetic model and Shelford’s tolerance law curve under the influence of natural environmental factors on plants, which are limiting for plants both in deficiency and excess. The analysis has shown that Shelford’s curve and hormetic model do not contradict but instead complement each other. The hormetic response of plants is localized in the stress zone of the Shelford’s curve when adaptive mechanisms are disabled within the ecological optimum. At the same time, in a species range, the ecological optimum is the most favorable combination of all or at least the most important environmental factors, each of which usually deviates slightly from its optimal value. Adaptive mechanisms cannot be completely disabled in the optimum, and hormesis covers optimum and stress zones. Hormesis can modify the plant tolerance range to environmental factors by preconditioning and makes limits of plant tolerance to environmental factors flexible to a certain extent. In turn, as a result of tolerance range evolution, quantitative characteristics of hormesis (width and magnitude of hormetic zone) as well as the range of stimulating doses, may significantly differ in various plant species and even populations and intra-population groups, including plants at different development stages. Using hormetic preconditioning for managing plant resistance to environmental limiting factors provides an important perspective for increasing the productivity of woody plants in forestry.

Forests produce several types of benefits to both forest landowners and society. The social benefit of private forestry is equal to private benefit plus positive externalities minus negative externalities. This study developed alternative metrics for the evaluation of the social benefit of forest management. Forest management was assessed in terms of five criteria: economic, socio-cultural, environmental and ecological performance and the resilience of the forest ecosystem. Each criterion was described with three numerical indicators. Alternative performance indices were calculated from the indicator values using methods developed for multi-criteria decision making. It was concluded that indices based on the multiplicative Cobb–Douglas utility function might be the most recommendable when forestry should produce a balanced combination of different ecosystem services. When the indices were used to compare alternative silvicultural systems in terms of their social performance, continuous cover management was ranked better than even-aged management. The performance of even-aged management improved when it aimed at increasing the share of mixed stands and broadleaf species. Maximizing net present value (NPV) with a 1% discount rate led to better social performance than maximizing NPV with a 4% discount rate.

The positive ecological interaction between gap formation and natural regeneration has been examined but little research has been carried out on the effects of gaps on natural regeneration in forests under different intensities of disturbance. This study evaluates the composition, diversity, regeneration density and abundance of natural regeneration of tree species in gaps in undisturbed, intermittently disturbed, and disturbed forest sites. Bia Tano Forest Reserve in Ghana was the study area and three gaps each were selected in the three forest site categories. Ten circular subsampling areas of 1 m² were delineated at 2 m spacing along north, south, east, and west transects within individual gaps. Data on natural regeneration < 350 cm height were gathered. The results show that the intensity of disturbance was disproportional to gap size. Species diversity differed significantly between undisturbed and disturbed sites and, also between intermittently disturbed and disturbed sites for Simpson’s (1-D), Equitability (J), and Berger–Parker (B–P) indices. However, there was no significant difference among forest sites for Shannon diversity (H) and Margalef richness (MI) indices. Tree species composition on the sites differed. Regeneration density on the disturbed site was significantly higher than on the two other sites. Greater abundance and density of shade-dependent species on all sites identified them as opportunistic replacements of gap-dependent pioneers. Pioneer species giving way to shade tolerant species is a natural process, thus make them worst variant in gap regeneration.

It is important to quantify and analyze forest spatial patterns for studying biological characteristics, population interaction and the relationship between the population and environment. In this study, the forest spatial structure unit was generated based on the Delaunay triangulation model (DTM), and the weights were generated using the comprehensive values of the tree diameter at breast height, total height and crown width. The distance between neighbors determined by the DTM was weighted to transform the original coordinates of trees into logical coordinates. Then, a weighted spatial pattern (WSP) was developed. After weighting, the neighboring trees were replaced, the replacement ratio was 38.3%, and there was 57.4% of the central tree. Correlation analysis showed that the uniform angle index of the WSP was significantly correlated with the tree size standard deviation under uniformity (r = 0.932) and randomness (r = 0.711). The DTM method not only considers the spatial distance between trees, but also considers the non-spatial attributes of trees. By changing the spatial topological relation between trees, this method further improves the spatial structure measurement of forest.

In some urban parks in Tokyo, semi-natural habitat patches are maintained as nature reserves for birds, called bird sanctuaries. Bird censuses and vegetation surveys were conducted in eight urban parks in Tokyo from December 2015 to July 2016 to determine the effectiveness of bird sanctuaries on avian species composition. The relationship between avian species composition and environmental conditions was analyzed by partial redundancy analysis (partial RDA) using vegetation variables, number of visitors, presence or absence of reserves within the same park, area of wooded parts, and normalized difference vegetation index (NDVI) in the surrounding area. The results of the partial RDA are as follows: (1) Area, lower vegetation cover, higher vegetation cover, tree species composition obtained from detrended correspondence analysis (DCA) on vegetation survey data, and NDVI in the surrounding area were considered as covariates and explained 17.4–33.6% of the total variation in bird species composition, (2) The presence or absence of sanctuary significantly explained bird species compositional variation regardless of season, indicating that the sanctuaries were beneficial for urban avoider species not only in the sanctuaries but also in the surrounding wooded area, and (3) Tree coverage within a 100 m range and leaf litter coverage also influenced avian species composition. We concluded that bird sanctuaries and other nature reserves can be beneficial to bird conservation, even within Tokyo. The positive effect of sanctuaries could be due to the limited influence of human presence and the developed vegetation within them. These reserves may play the role of core habitats within the studied urban parks.

Preventing and suppressing forest fires is one of the main tasks of forestry agencies to reduce resource loss and requires a thorough understanding of the importance of factors affecting their occurrence. This study was carried out in forest plantations on Maoer Mountain in order to develop models for predicting the moisture content of dead fine fuel using meteorological and soil variables. Models by Nelson (Can J For Res 14:597–600, 1984) and Van Wagner and Pickett (Can For Service 33, 1985) describing the equilibrium moisture content as a function of relative humidity and temperature were evaluated. A random forest and generalized additive models were built to select the most important meteorological variables affecting fuel moisture content. Nelson's (Can J For Res 14:597–600, 1984) model was accurate for Pinus koraiensis, Pinus sylvestris, Larix gmelinii and mixed Larix gmelinii—Ulmus propinqua fuels. The random forest model showed that temperature and relative humidity were the most important factors affecting fuel moisture content. The generalized additive regression model showed that temperature, relative humidity and rain were the main drivers affecting fuel moisture content. In addition to the combined effects of temperature, rainfall and relative humidity, solar radiation or wind speed were also significant on some sites. In P. koraiensis and P. sylvestris plantations, where soil parameters were measured, rain, soil moisture and temperature were the main factors of fuel moisture content. The accuracies of the random forest model and generalized additive model were similar, however, the random forest model was more accurate but underestimated the effect of rain on fuel moisture.

Intercropping of mulberry (Morus alba L.) and alfalfa (Medicago sativa L.) is a new forestry-grass compound model in China, which can provide high forage yields with high protein. Nitrogen application is one of the important factors determining the production and quality of this system. To elucidate the advantages of intercropping and nitrogen application, we analyzed the changes of physicochemical properties, enzyme activities, and microbial communities in the rhizosphere soil. We used principal components analysis (PCA) and redundancy discriminators analysis to clarify the relationships among treatments and between treatments and environmental factors, respectively. The results showed that nitrogen application significantly increased pH value, available nitrogen content, soil water content (SWC), and urea (URE) activity in rhizosphere soil of monoculture mulberry. In contrast, intercropping and intercropping + N significantly decreased pH and SWC in mulberry treatments. Nitrogen, intercropping and intercropping + N sharply reduced soil organic matter content and SWC in alfalfa treatments. Nitrogen, intercropping, and intercropping + N increased the values of McIntosh diversity (U), Simpson diversity (D), and Shannon–Weaver diversity (H′) in mulberry treatments. However, PCA scatter plots showed clustering of monoculture mulberry with nitrogen (MNE) and intercropping mulberry without nitrogen (M0). Intercropping reduced both H′ and D but nitrogen application showed no effect on diversity of microbial communities in alfalfa. There were obvious differences in using the six types of carbon sources between mulberry and alfalfa treatments. Nitrogen and intercropping increased the numbers of sole carbon substrate in mulberry treatments where the relative use rate exceeded 4%. While the numbers declined in alfalfa with nitrogen and intercropping. RDA indicated that URE was positive when intercropping mulberry was treated with nitrogen, but was negative in monoculture alfalfa treated with nitrogen. Soil pH and SWC were positive with mulberry treatments but were negative with alfalfa treatments. Intercropping with alfalfa benefited mulberry in the absence of nitrogen application. Intercropping with alfalfa and nitrogen application could improve the microbial community function and diversity in rhizosphere soil of mulberry. The microbial community in rhizosphere soil of mulberry and alfalfa is strategically complementary in terms of using carbon sources.

Plant species produce different types of allelopathic chemicals in nature; however, little is known about the differential regulation of plant allelopathy. Because allelopathy caused by p-hydroxybenzoic acid (pHBA) is one of the main obstacles to continuous cropping of Populus ×  euramericana ‘Neva’, we examined gene expression dynamics in Neva leaves induced by pHBA. The expression of genes related to photosynthesis and respiration changed, while mRNA involved in regulating gene expression during allelopathy was degraded. Some miRNAs that are involved in plant allelopathy target crucial genes for regulating reactive oxygen species. Moreover, coexpression regulatory networks were constructed based on profiles of the identified miRNA-target interactions and the differentially expressed miRNA–target pairs. These findings provide a mechanistic framework for understanding allelopathy in plants.

Growth traits and genetic diversity of 23 provenances of Quercus rubra introduced from North America were analyzed in a provenance trial established with a randomized block design in Hwaseong, Gyeonggi, South Korea in 1993. Growth variables and survival at age 25 were compared with results from early stages. Height, DBH, volume and stem straightness of Q. rubra was better than those of the domestic oak (Quercus accutissima). Growth of the Dunham Island provenance from New York was the best among the 23 provenances that of the Eagle River provenance from Wisconsin was poorest. Survival rate at age 25 was on average 52%. The longitude of seed origin and growth of provenance were consistently significantly negatively correlated at all ages. Growth of coastal provenances was superior to that of the inland provenances, which were separated by the Appalachian Mountains. Genetic diversity and genetic distance among the provenances were evaluated using microsatellite markers. The allelic frequencies showed high polymorphism in 10 microsatellite loci, and 292 alleles were found. Of 10 loci, two were commonly found in the 23 provenances. The mean allelic diversity and heterozygosity observed among the provenances were similar to those from the native populations of Q. rubra in North America. Nei′s genetic distance among the 23 was estimated and showed that a clear trend between geographic and genetic distances, indicating that some provenances have high genetic diversity with superior growth performance.

Quercus L. has significant societal, ecological and economic benefits in the Northern Hemisphere. However, species identification among oaks is notoriously difficult. China harbours highly diverse oaks, of which the diversity of white oaks is the most extensive; however, to date, the evolution of chloroplast (cp) genomes in white oaks in China has not been comprehensively studied. Thus, we sequenced the complete cp genomes (161,254 bp, 161,229 bp and 161,254 bp in size) of three white oak species (Quercus serrata Thunb. var. brevipetiolata A. DC. Nakai, Quercus wutaishansea Mary and Quercus mongolica Fischer ex Ledebour, respectively). Six white oak species (Quercus aliena Blume, Quercus dentata Thunb., Quercus aliena Blume var. acutiserrata Maximowicz ex Wenzig, Q. serrata var. brevipetiolata, Q. wutaishanica and Q. mongolica) and five other Fagaceae species (Quercus rubra L., Quercus variabilis Bl., Quercus aquifolioides Rehd. et Wils., Fagus engleriana Seem. and Castanea henryi Skan Rehd. et Wils.) were retrieved for comparative analyses. We detected 11 highly divergent regions (psbA, matK/rps16, rps16, trnS-GCU/trnG-GCC, trnR-UCU/atpA, trnT-GGU/psbD, ndhJ, ndhJ/ndhK, accD, ndhF and ycfI) through comparative analyses and these regions might be used as molecular markers. The ω ratio of the rps12, rpoC2 and ycf1 genes was greater than 1 in several comparison groups between white oaks and the petA gene was subjected to significant positive selection between the comparison of six white oaks and Q. variabilis. Phylogenetic analyses revealed that six white oaks were grouped with Q. rubra, forming a single clade.

Five Larix species (L. griffithii, L. speciose, L. himalaica, L. kongboensis, and L. potaninii var. australis), have survived on the Qinghai-Tibet Plateau (QTP) under specific climate conditions for decades. The lack of genomic information seriously hinders research on the evolution, conservation and ecology of these Larix resources. In this study, complete chloroplast (cp) genomes of the 5 species were assembled and compared based on next generation sequencing technology combined with polymerase chain reaction validation. The results show that the 5 cp genomes are relatively conservative in size, gene content and arrangement, and border variation. Phylogenetic analysis showed that the species are closely related as well as to seven other species of the same genus. In addition, the 5 cp genomes contained few simple sequence repeats and relatively low nucleotide variability; thus, 12 candidate polymorphic cp DNA markers will be helpful for further research on relevant population genetics. These results will provide valuable genetic information for the conservation, evolution and ecology of these species and their relatives.