The aim of the current study is to carry out an analysis of energy sources and find a source with the lowest ecological footprint; it is based on a desk study using data from databases that centralize energy sources globally. Currently, energy is sourced from seven types of resources: fossil fuels, hydro, solar, wind, nuclear, bio-fuel (biodiesel, biomass, ethanol, wood, etc.), and geothermal. The combustion of hydrogen obtained by electrolysis is still at the prototype stage. In recent decades, studies have focused on renewable sources, with the main focus on wind and solar energy. In 2019, the global energy produced from renewable sources represented only 7%, registering an increase of only 4% compared to 2000. This small increase indicates the premise of a long transition process, accompanied by increases in energy prices and inefficiency in the current use other alternative energy sources compared with fossil fuels. The most cost-effective energy source of the future is biomass because it is an inexhaustible source of energy, which regenerates at a rapid rate; it is produced naturally without the need for infrastructure and equipment; it fixes the CO2 produced by its combustion during the process of photosynthesis, with zero risk compared to nuclear energy. The extraction of biomass from different crops, including woody species (trees and shrubs), represents a way of reducing the pressure on wild plant diversity. The energy source with the most advantages regarding energy production is plant biomass; future studies should be oriented towards this source.

Acer campestre L. is naturally distributed in most of Europe. The species can serve as a valuable model for researching the sensitivity of populations to habitat fragmentation. This research aims to determine whether there is a differentiation of field maple populations based on their division by ecological-vegetation regions, precipitation amounts, temperatures, and altitudes of the populations. The material was collected from 25 populations in Bosnia and Herzegovina, from different ecological-vegetation areas, with twelve trees per population and five fruits and ten leaves per tree. Then, 10 fruit properties and 19 leaf properties were analyzed. A discriminant analysis was performed for population groups based on the ecological-vegetation area, amount of precipitation, average annual air temperature and altitude. The discriminant analysis results showed the distinguishing of groups of populations in the sub-Mediterranean area, and groups of populations with an average annual temperature of 14.00 to 15.99 °C. There was no clear separation of the groups according to the average annual precipitation or altitude. The analysis of the connection established that the influence of environmental factors is more pronounced compared to geographical factors. The key ecological variable that determines morphological separation was temperature and to a lesser extent precipitation. The results of this research will be used in planning of afforestation of suitable, unvegetated land and extreme habitats in the southern and southwestern parts of Bosnia and Herzegovina with Acer campestre.

The study examined the effect of the pod colors as an index of maturity phases on seed traits of silk tree (Albizia julibrissin Durazz). Silk tree pods were simultaneously collected at five maturity phases based on pods color in late September in the Hyrcanian plain forest, Tashbandan-Iran. Seeds were removed from pods and seed moisture content (MC), 1000 seed weight (1000 SW) and germination performance were determined. Maturity phases affected seed MC and 1000 SW. MC and 1000 SW were the highest at the pod color of full green (61% and 64.2 g, respectively). As the seeds matured, MC and 1000 SW decreased, and the lowest MC and 1000 SW were found as 8.5% and 36.2 g, respectively at seeds harvested at the dark brown stage. Germination percentage (GP), germination speed (GS) and mean germination time (MGT) were significantly affected by seed maturity phases, and GP and GS were the lowest in the dark brown pod stage (6% and 0.2, respectively). GP and GS was the highest at seeds harvested at the half green-half brown stage. MGT was increased to the maximum when seeds were harvested at the dark brown pod stage (29.8). This study showed that when pods have reached maturity, the coats of the seeds have no barrier to germination but as ripening continues, germination of silk seeds were hindered by impervious seed coats that retard the entry of water. The study revealed that pod color could be used as an indicator for physical dormancy level of silk tree seeds.

This article analyses the existing and possible limitations to an increased circularity in forest-based value chains in the construction, furniture manufacturing, cellulose-based fibers, and plastics sectors. The analysis provides evidence that not all forest-based value chains can be circular in all circumstances. In some cases, the focus on circularity may cause environmental externalities, in other, it may not guarantee economic viability. Information analyzed comes desk research of existing scientific papers and previous reports. It was complemented by information from websites of organizations promoting circular economy and sustainability concepts. The analysis focuses on countries where these concepts are present in policy and research agendas, and consequently, are better documented in English scientific literature. In addition, opinion articles and discussions during the International Conference on Cellulose Fibers in Cologne, Germany, editions 2020, 2021 and 2022 served as a starting point for formulating original ideas and suggestions. The article concludes that to ensure sustainability of the forest-based value chains, continuous consideration, and coordination of circularity at all stages of the value chains are needed. In addition, the transition to a sustainable and circular bioeconomy needs to be enabled by the legislator and develop organically, based on the location of industries, proximity to available (waste) resources and the consumer preferences. These coordinated actions will require involvement and cooperation of different actors outside the existing sectoral silos towards a more cross-cutting value chains approach, at all levels. This will allow a progressive transition towards a comprehensive circular, bio-based system. Market forces will guide this process.

Increasing urbanization in the world in recent years has resulted in the replacement of areas covered with plants by buildings. Because of this change, urban areas are warmer than rural areas (urban heat island). In this investigation, the urban heat island (UHI) effect, the methods of combating this effect and notably the role of urban trees are exhaustively elaborated by considering the relevant literature. In addition, suggestions were made on which species should be selected and how tree species should be positioned to reduce UHI effect. There are solid evidences that trees, urban green spaces and wider green infrastructure can bring significant reductions in urban temperatures. Urban planners and decision makers can help combat UHI and increase urban resilience to the effects of climate change, primarily by planting the urban environment with extensive shade-providing species and harnessing the most of the opportunities afforded by restoration activities. Trees and other vegetation can cool the surrounding air by evapotranspiration thanks to both transpiration from plant leaves and evaporation of water from irrigated soil. The tree canopy can considerably improve outdoor thermal comfort by preventing a pedestrian from being exposed to solar radiation, and also by protecting floors and building coverings from UHI effect. Furthermore, if a roadside afforestation is to be established to combat UHI effect, a proper plan based on the character of the road will be beneficial in terms of achieving the determined goals. Eventually, the adaptation to UHI should be achieved to plan short-, medium- and long-term changes.

Nature-based solutions (NBSs), a sustainable landscape restoration approach, covers rebuilding ecological functionality and integrity in a watershed. The objective of restoration with NBSs is to revitalize the ecosystems to provide and sustain multiple services. Therefore, it is more than just planting trees or rewetting wetlands. NBSs can provide effective landscape restoration and management tools but should be applied on a methodological basis to get the full benefits. The methodological basis includes the type and nature of NBS, the application principles, and the tools to assess the efficiency of the set of NBS applied. However, most literature on NBSs is theoretical, while practitioners need applicable guidance. In this paper, we reviewed the latest literature on the NBSs and tried to connect the theory with some practical examples. We also underlined that NBSs applied in landscape restoration should relate to watershed processes since streamflow and/or stream quality are significant performance indicators. The NBSs should strengthen the resiliency towards multiple stressors and disturbances in a landscape. The widespread stressors in Türkiye landscapes are related to water balance that compares precipitation and evapotranspiration. Therefore, we suggest Budyko theory application in evaluating NBS options instead of typical climate models. Overall, this paper defines NBSs, provides examples, discusses possible methodologies, and comes up with some practical conclusions. The points we discuss are the resiliency assessment approach, scale, and location of the application, identifying the problems in a watershed through adequate quantitative indicators, and setting up the thresholds planned to be achieved.