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The study examined the growth characteristics of the Siberian spruce (Picea obovata Ledeb.) under the canopy of coniferous forests in early ontogeny. We revealed that spruce undergrowth in adverse conditions is suppressed, is slow to grow and has xylorhizomes. The result is a significant difference in height, age and stage of ontogeny that affects the forest’s growth dynamics. The formation of xylorhizomes changes the relative dimensions of the above-ground part and the plant’s absolute height from 42 to 75%, depending on age. We identified two periods of growth intensity (slow and stable) and the critical age for spruce undergrowth to move from one stage of ontogeny to the next. If it does not make the transition, it will die. There are two strategies for developing spruce undergrowth: a “direct” path during rapid growth and a “waiting” path when the plants are suppressed. Such growth pathways in the pre-generative stage of the Siberian spruce’s ontogeny allow the undergrowth, even in a suppressed state, to survive in an adverse environment under the forest canopy.

By providing ecosystem services, urban forests contribute significantly to the well-being of urban populations. Urban forests, along with other urban green spaces, are often the closest natural environment in the city where a child can play. The majority of pre-school children spend a large part of the day in kindergarten, which means that forest visits should have a prominent place in the kindergarten curriculum. Therefore, this study focuses on making the forest more suitable and thus more accessible for visits with children. The first goal of the research is to identify teachers&rsquo, preferences for the forest environment they visit with a group of pre-school children. The second goal is to present a forest suitability model for a visit with kindergarten children based on the teachers&rsquo, preferences. Based on the research survey conducted among the teachers in Slovenian public kindergartens, we formed and evaluated the criteria for the construction of a model of forest suitability for a visit with children. As the most important requirement for visiting a forest, the teachers note its proximity. They prefer a mature, mixed forest, with a bit of undergrowth, dead wood, and a presence of water and a meadow. Based on the identified criteria, we used the multi-criteria evaluation method in the GIS-environment in order to build a model of urban forest suitability for a visit with kindergarten groups of children in the study area of the City of Ljubljana, Slovenia. The results are useful in urban forest planning and management to ensure better forest suitability and accessibility for visits by children. Suitability maps can be used as one of the spatial foundations necessary for an integrated urban forest planning with emphasis on social functions. The model can be adapted beyond Slovenia to different spatial and social requirements and contexts.

Continuous cover forestry (CCF) aims to emulate small natural disturbances and take advantage of natural regeneration. To implement these management practices successfully, knowledge of advance regeneration under the canopy in different conditions is crucial. Therefore, the aim of this study was to assess the influence of stand inventory parameters of canopy layer (age, basal area, height, and density) on the probability and density of advance regeneration of the Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) in hemiboreal forests in Latvia. The data were obtained from the National Forest Inventory, from a total of 879 plots. In the study, only Norway spruce or Scots pine dominated stands were used and the sampled stand age ranged from 21 to 218 years. The probability of advance regeneration differed between stands dominated by Scots pine versus Norway spruce. The probability and density of the advance regeneration of Norway spruce were positively linked to increased stand age, whereas the probability of the advance regeneration of Scots pine was negatively linked to the basal area of the stand. In stands dominated by Norway spruce and Scots pine on mesic soils, the advance regeneration of Norway spruce has a high density, whereas the advance regeneration of Scots pine is sporadic and scarce.

The purpose of the research was the recognition of edge effects regarding similarities and differences of vascular flora in undergrowth layers in the urban forest ecotones. Four types of urban forest neighborhoods were analyzed: ecotones adjacent to the manor park, the agriculture field, housing estates and the road. The plant compositions in the forest ecotones were compared with the plant compositions in the urban forest interior and the forest nature reserve. The phytosociological type of studied forests was a subcontinental oak-hornbeam one (Tilio-Carpinetum). Diagnostic plant species (e.g., characteristic) for forests from the non-diagnostic ones were identified. Forest consistent plant species dominated in the ecotone adjacent to the manor park and in the interior of urban forests too, but the best conditions for these plants were inside the forest nature reserve, where native consistent forest plants showed the highest dominance when comparing all studied areas. A higher anthropogenic pressure from the adjacent areas results in supporting the growth of inconsistent plant species in the forests, and these plants are mostly represented by plants belonging to grass and synanthropic communities. Another conclusion drawn from our research is that the protected forest, represented by a nature reserve in the city, provides better “shelter” for native forest plants than the urban forest without any protection. Ultimately, a permanent challenge is to achieve and maintain the balance between nature and the impact of anthropogenic activities on urban forests in the city. The high quality of green areas, biodiversity, including forests, implicates possibilities of sustainable development in cities. The research results will be useful for local urban planners and ecologists during their work on strategies of city development, including shaping of green infrastructure.

The cover of introduced tree species in Europe has recently increased, due to several factors. Attempts to understand the impact of non-native edificator trees on the environmental conditions and diversity of undergrowth have so far been limited to a few studies. In this paper, we analyse the effect of one of the most commonly planted non-native tree species&ndash, black pine (Pinus nigra J. F. Arnold) in the Carpathian-Pannonian region, north of the border of its native occurrence. The objectives of our study were to determine the following: (i) How does black pine, as a non-native edificator, change the forest structure and environmental conditions in comparison to those of native communities? (ii) How does black pine change the species composition of undergrowth in comparison to that of native communities? (iii) Which factors are associated with the impact of black pine on diversity? To answer these questions, we used the twin plot method, sampling two neighbouring plots with the same environmental conditions in which one plot of the pair is in a forest with native tree species composition and the second plot is in a planted non-native Pinus nigra plantation. We found that in forests dominated by the non-native black pine, (a) the tree canopy is significantly more open, (b) the cover of the shrub layer is significantly higher, (c) the needles of black pine form a significantly thicker litter layer and (d) the cover of the herb layer is significantly lower than that in the native forest. (e) Black pine plays a vital role in modifying local climate by altering air temperature and humidity, (f) there were no significant differences in the soil pH between black pine plantations and native forests, (g) the plantations of black pine cause changes in diversity at both the species and the community level and (h) the dissimilarity between black pine plantations and neighbouring native forests decreases at higher altitudes.

The study examines the influence of Polish primitive horse grazing on vegetation in deciduous and coniferous old forest stands in north-east Poland. It was conducted in both forest sites in two complexes located in: (i) the fenced area of the Popielno Research Station of the Polish Academy of Sciences, with free-living Polish pony [Polish primitive horse (Equus ferus caballus Linnaeus, 1758)] in 130-year-old stands, and (ii) in the open 116-year-old managed (harvested) Maskulińskie Forest District, without horses. In both areas the stands are inhabited by free-living red and roe deer. The impact of forest animals on ground cover layer as well as on understory shrub layer and undergrowth was compared. Very significant differences in the structure of the understory and undergrowth (above 0.5 m) layer vegetation communities between both areas and type of stands were found. The results suggest that the presence of the Polish horse substantially changed the species composition and increased the species diversity of the ground layer and shrub layer both in the coniferous forest and deciduous forest habitats. The height of the shrub layer trees was lower by 30% in the area with the Polish horse. The level of biodiversity of forest plants was dependent on the presence of the Polish horse, which in the past was one of the natural inhabitants of forests in the area of research.

Monitoring plant phenology is one of the means of detecting the response of vegetation to changing environmental conditions. One approach for the study of vegetation phenology from local to global scales is to apply satellite-based indices. We investigated the potential of phenological metrics from moderate resolution remotely sensed data to monitor the altitudinal variations in phenological phases of European beech (Fagus sylvatica L.). Phenological metrics were derived from the NDVI annual trajectories fitted with double sigmoid logistic function. Validation of the satellite-derived phenological metrics was necessary, thus the multiple-year ground observations of phenological phases from twelve beech stands along the altitudinal gradient were employed. In five stands, the validation process was supported with annual (in 2011) phenological observations of the undergrowth and understory vegetation, measurements of the leaf area index (LAI), and with laboratory spectral analyses of forest components reflecting the red and near-infrared radiation. Non-significant differences between the satellite-derived phenological metrics and the in situ observed phenological phases of the beginning of leaf onset (LO_10), end of leaf onset (LO_100), and 80% leaf coloring (LC_80) were detected. Next, the altitude dependent variations of the phenological metrics were investigated in all beech-dominated pixels over the area between latitudes 47&deg, 44&prime, N and 49&deg, 37&prime, N, and longitudes 16&deg, 50&prime, E and 22&deg, 34&prime, E (Slovakia, Central Europe). In all cases, this large-scale regression revealed non-linear relationships. Since spring phenological metrics showed strong dependence on altitude, only a weak relationship was detected between autumn phenological metric and altitude. The effect of altitude was evaluated through differences in local climatic conditions, especially temperature and precipitation. We used normal values from the last 30 years to evaluate the altitude-conditioned differences in the growing season length in 12 study stands. The approach presented in this paper contributes to a more explicit understanding of satellite data-based beech phenology along the altitudinal gradient, and will be useful for determining the optimal distribution range of European beech under changing climate conditions.

With the continuous increase in plantation areas, the reduction of natural forest areas, and the unreasonable management of plantations by human beings, the service function of forest ecosystems has gradually reduced. Therefore, close-to-natural forestry has become important for the sustainable development of modern forestry. However, the differences in soil properties, enzyme activities, microbial diversities, and undergrowth vegetation species diversities have not been systematically explained for Chinese fir (Cunninghamia lanceolata). How do these indicators interact? The purpose of this paper was to study the difference in soil properties and biodiversity in different aged Chinese fir plantations and close-to-natural forests to explore their interactions and to provide direction for close-to-nature management. The results showed that the above indicators were significantly different in different aged Chinese fir plantations, soil pH, organic matter, total nitrogen, total phosphorus, total potassium, alkali-hydrolyzed nitrogen, available phosphorus concentrations, and urease activities in close-to-natural forests were significantly higher than plantations. It is worth mentioning that the richness of undergrowth vegetation species diversity (especially shrubs) and soil microbial diversities (especially fungi) in the close-to-natural forests were obviously higher than those in plantations. The correlation analysis results showed that the diversity of shrub species with respect to soil properties presented a higher correlation than herb species, the diversity of fungi with respect to soil properties presented a higher correlation than that observed for bacteria, and the diversity of fungi were significantly correlated with the diversity of undergrowth vegetation species diversities, but the correlation between bacteria and undergrowth vegetation species diversities was not significant. Our results suggest that the above factors are fundamental factors for the transformation of Chinese fir plantations to close-to-natural forests. To realize close-to-natural forestry, we must change the tree structure, combine the difference of those factors in different aged plantations, restore undergrowth vegetation species diversity, and thus improve microbial diversity and increase decomposition, transformation, and improvement of soil properties.

Research Highlights: Thermophilous oak forests are among the most species-rich forest ecosystems in Central Europe. In the temperate zone, they evolved from mixed deciduous forests due to centuries-long livestock grazing. The abandonment of traditional forms of landscape use resulted in a constant decline in the number of patches of these communities, their area and species richness, which has been ongoing for decades and calls for their urgent conservation. The commonly used approaches to the conservation of this community are the reestablishment of grazing or mechanical removal of undergrowth. However, there are a limited number of works comparing their effects on the forest herb layer separately and in combination. Background and Objectives: The purpose of our research was to evaluate the effectiveness of grazing, mechanical brush removal and their combination for the conservation of the oak forest herb layer. Materials and Methods: Our work was based on a fully crossed experimental design set in a 60-year-old oak forest. The individual and combined influences of sheep grazing and brush cutting on forest floor vegetation were compared to control plots. We surveyed plant species twice&mdash, before the application of treatments and one year later on 600 one-square-meter subplots selected randomly in the limits of twelve fenced 20 m &times, 20 m treated and untreated study plots. Results: Both grazing by sheep and mechanical removal served well for total plant species richness and their cover, if applied separately. But these effects were not additive&mdash, plant species richness and plant cover on plots with combined treatment did not differ from plots, where just a single treatment was applied. Application of both treatments (but separately) had positive influence on species cover of the target group of plants typical to xerothermic oak forests and non-target species of mixed deciduous forests. Mechanical removal allowed also for successful control of woody species. Active conservation measures resulted also in negative effects&mdash, we observed increase in the species richness and cover of ruderal species on grazed plots. Conclusions: Both tested methods can be used for active conservation of open oak forest understorey vegetation. The method of active conservation should be chosen depending on the goal and the species composition of the forest floor and undergrowth found at the beginning of the restoration process, however, combining of these treatments does not bring any extra advantage. In our opinion a monitoring of the reaction of vegetation on treatments is of paramount importance.

Stand density directly affects the distribution of ecological factors such as light, heat, and water in forest communities and changes the diversity and structure of undergrowth species, thereby affecting soil health. Fine roots can provide water and nutrients to plants rapidly in the fierce competition of soil resources, so as to get rid of environmental factors. This study examined the fine-root responses of the Populus tomentosa clone S86 to three stand densities (plant &times, row spacing: 2 &times, 2 m, 4 &times, 3 m, 4 &times, 5 m). We measured the biomass, morphology, and nitrogen content of lower- (1&ndash, 3 order) and higher-order (&gt, 3 order) fine roots, and analyzed soil chemical properties in 10&ndash, 30 cm. The soil from the density (2 &times, 2 m) stands showed lower soil organic matter content, available nitrogen, available phosphorous, and available potassium than others. Obviously, lower and higher-order fine roots were different: biomass of the &gt, 3 order accounted for 77&ndash, 87% of the total biomass, 1&ndash, 3-order fine-root diameter around 0.28&ndash, 0.38 mm, while &gt, 3-order fine root were 1.28&ndash, 1.69 mm, the length of 1&ndash, 3-order fine root was longer than the &gt, 3 order, and root length density, specific root length, and nutrient content between the 1&ndash, 3 and &gt, 3 orders were different. At 2 &times, 2 m, 1&ndash, 3-order fine-root biomass was the highest, 132.5 g/m3, and the 1&ndash, 3-order fine-root length, diameter, surface, root length density was also the highest, at the same time, the 1&ndash, 3-order fine-root total nitrogen and organic matter content was also the highest, while the &gt, 3 order was highest under 4 &times, 3 m or 4 &times, 5 m. The findings of this study show that stand density affected the available nutrient content of the soil. When soil resources were poor, the biomass, morphology, and chemical content of fine roots were adjusted to increase the nutrient absorption rate, particularly in the lower-order roots.

The pattern of soil carbon stock is atypical along the slope position in a seasonally dry tropical forest, the mean stock values increase from the lower, middle, to upper slopes, at 11.5, 13.2, and 15.5 kg m&minus, 2, respectively. In sloping landscapes, soil organic carbon tends to accumulate in lower slopes, but our previous soil respiration study suggested that soil carbon stock distribution along the slope position in seasonally dry tropical forests is atypical. The aims of this study were: (i) to examine whether the atypical pattern occurs widely in the watershed, and (ii) to examine the pattern of root development in the soil profile as a source of soil carbon. The density and stock of soil carbon in three soil layers (0&ndash, 10, 10&ndash, 30, and 30&ndash, 100 cm) of 13 soil profiles were compared in different positions on the slope (upper, middle, and lower). Root biomass at each slope position was also determined. Soil carbon density in each layer increased significantly with an increase in the relative position of the slopes, particularly in the 10&ndash, 30 cm soil layer. The density of medium root (3&ndash, 10 mm in diameter) in the upper slopes was significantly higher than that in the middle and lower slopes, especially for 15&ndash, 60 cm soil layers. The atypical pattern of soil carbon accumulation along the slope position occurred widely in the studied watershed and appeared to be caused by the development of root systems in deeply weathered soil under xeric soil conditions in the upper slopes. Roots of bamboo undergrowth may also contribute to soil carbon stabilization by reducing soil erosion in the surface soil.

Gaps by thinning can have different microclimatic environments compared to surrounding areas, depending on the size of the gap. In addition, gaps can play important roles in biological dynamics, nutrient cycling, and seedling regeneration. The impacts of gap size on soil microbial communities and enzyme activities in different soil layers in Chinese pine plantations are not well understood. Here, we created gaps of 45 m2 (small, G1), 100 m2 (medium, G2), and 190 m2 (large, G3) by thinning unhealthy trees in an aged (i.e., 50 years old) monoculture Chinese pine plantation in 2010. Soil samples were collected in 2015. The total, bacterial, Gram-positive (G+), and Gram-negative (G&minus, ) phospholipid fatty acid (PLFA) profiles were highest in medium gaps in both the organic and mineral layers. These indicesdecreased sharply as gap size increased to 190 m2, and each of the detected enzyme activities demonstrated the same trend. Under all the gap size managements, abundances of microbial PLFAs and enzyme activities in the organic layers were higher than in the mineral layers. The soil layer was found to have a stronger influence on soil microbial communities than gap size. Redundancy analysis (RDA) based on the three systems with different gap sizes showed that undergrowth coverage, diversity, soil total nitrogen (TN), total organic carbon (TOC), and available phosphorus (AT) significantly affected soil microbial communities. Our findings highlighted that the effect of gap size on soil microenvironment is valuable information for assessing soil fertility. Medium gaps (i.e., 100 m2) have higher microbial PLFAs, enzyme activity, and soil nutrient availability. These medium gaps are considered favorable for soil microbial communities and fertility studied in a Chinese pine plantation managed on the Loess Plateau.

Pedunculate and sessile oak species are sympatric. These oaks hybridize with one another, and this process influences the development of undergrowth. The purpose of this study was to determine how different oak species influence the forest regeneration process. For this purpose, the forest was divided into eight transects of 300 m and 100 m widths, distinguished into temporary plots of 10 m in diameter covering the whole territory of the forest. The distribution of oak undergrowth was calculated by four oak height groups, determining the composition of the first storey, covering of underbrush and herbaceous plant, and forest site. We determined that the spread of oak differed depending on the first storey tree species and underbrush. Grass cover was the biggest influence on the sessile oak. The impurity of sessile oak in oak stands had a positive impact on the development of undergrowth, since the entire undergrowth develops faster than separate components of the undergrowth.