Tree species composition affects the abundance of rowan (Sorbus aucuparia L.) in urban forests in Finland

Exploring Dendroflora Diversity and Ecology in an Urban Arboretum from Western Romania: The Role of Plant Life-Form and Plant Family in Urban Woody Phytocoenosis

The dendroflora of an urban arboretum (The Botanic Park of Timișoara, Romania), consisting of 193 species, was ecologically characterized as bioforms, phytogeographical elements, and preferences for moisture, temperature, and soil pH. The aim of the research was to determine whether the native ecological requirements of the woody species, along with certain biological and evolutionary traits of them, such as plant life-form and plant family, could serve as tools for explaining and understanding the strategies employed by the urban woody phytocoenoses to acclimate and adapt to an established environment, such as an urban arboretum. The inventoried species are grouped in 111 genera and 45 families. The native and non-native dendroflora share 16 common families. The most representative family both in the native and non-native dendroflora is Rosaceae. The monotypic families are largely present (22.22% in the native dendroflora, and 42.22% in the non-native dendroflora). The plant life-form spectrum is dominated by megaphanerophytes (49%), followed by mesophanerophytes (41%). The chorological spectrum of the native species comprises 16 chorological types and is dominated by Eurasians (32%) and Europeans (30%). The species characteristics of the Pontic-Carpathian space, to which Romania belongs, are rare in the analyzed urban botanical park (4%). The mesophyte, mesothermal and slightly acido-neutrophilous species dominate both the native and non-native dendroflora. In the acclimation process of the non-native dendroflora, 37% of species exceeded their native requirements for moisture, 41% for temperature, and 50% for soil pH. The species requirements for temperature are associated to those for moisture and soil pH. The results show the potential of the analysed woody species to exceed their native requirements within the acclimation and adaption process, and in this process, for the studied temperate site, the plant life-form is important, and also the plant family. The species of the analyzed urban arboretum, both native and non-native, are taxonomically and biogeographically diverse, with specific habitat requirements, suggesting their great ability in acclimating, adapting and resisting.

Valorization of Bark from Short Rotation Trees by Temperature-Programmed Slow Pyrolysis

The tree bark represents an abundant but currently underutilized forest biomass side stream. In this work, temperature-programmed slow pyrolysis with fractional condensation was used for thermochemical conversion of the bark obtained from three short rotation tree species, aspen, goat willow, and rowan. Heating was performed in three stages, drying (135 °C), torrefaction (275 °C), and pyrolysis (350 °C), and the resulting vapors were condensed at 120, 70, and 5 °C, producing nine liquid fractions. An additional fraction was collected in the pyrolysis stage at 0 °C. The obtained liquid fractions were characterized in terms of their yields and bulk chemistry (i.e., CHNOS content, water content, pH, and total acid number) as well as their molecular level chemistry by high-resolution mass spectrometry. The highest liquid yields were obtained for the fractions condensed at 70 °C. The water content varied considerably, being the highest for the drying fractions (>96%) and the lowest for the pyrolysis fractions obtained at 120 °C (0.1-2%). Considerable compositional differences were observed between the liquid fractions. While the drying fractions contained mostly some dissolved phenolics, the torrefaction fractions contained more sugaric compounds. In contrast, the pyrolysis fractions were enriched lipids (e.g., suberinic fatty acids and their derivatives) and alicyclic/aromatic hydrocarbons. These fractions could be further refined into different platforms and/or specialty chemicals. Thus, slow pyrolysis with fractional condensation offers a potential route for the valorization of tree bark residues from forest industry.

The Status of Prunus padus L. (Bird Cherry) in Forest Communities throughout Europe and Asia

Prunus padus L. (bird cherry) belongs to the Racemosa group in subgenus Padus in the genus Prunus L. It is a hardy invasive species, which makes it valuable for securing slopes, and for eco-design. It is a good solitary park tree with early flowering of white flowers in racemes, which have a pleasant smell. However, it may be attacked by cherry-oat aphid, and the small ermine moth, which may weave giant webs over the whole tree, which demonstrates the important role of P. padus in the food web of forest ecosystems. The species is in balance with these pests, other herbivores and diseases throughout Europe and Asia. Another threat is the competition against the invasive P. serotina, but it seems that P. padus is not strongly threatened, though they compete for the same habitats. Moreover, human interference of forest community ecology is probably the greatest threat. The tree is not only winter hardy; it can also survive hot summers and tolerate a wide variety of soil types. It may form dense thickets due to the regeneration of branches bent to the ground and basal shoots, and may be invasive. These characteristics are important in determining the ecological niche of P. padus, which involves the position of the species within an ecosystem, comprising both its habitat requirements and the functional role. It is also important that P. padus has effective dispersal of pollen and seeds. This, together with the previously noted characteristics and the fact that the tree can cope well with climate change, define it as a not threatened species. However, the ssp. borealis is threatened and national level monitoring is required. Prunus padus has been exploited by farmers and rural population, but is less used today. However, it is still used for making syrup, jam and liquor. Moreover, the wood is valuable for wood carving and making cabinets. All tissues are valuable as sources of powerful natural antioxidants. However, the interest in the P. padus fruit and other tissues is overshadowed by the interest in other wild species of edible and human health-related berries. Moreover, the tree is used in horticulture as an ornamental in gardens and parks, values that deserve a new focus.