Ecological impact of fire place use in urban forests and consequences for visitor management

Urban forests are popular recreation areas in Europe. At the same time, these forests are important habitats for plants and animals and often harbour a high biodiversity. Recreational activities, for example picnicking and grilling and in particular the creation and usage of fire rings outside official picnic sites ("wild" fire rings), can cause extensive damage to soil and vegetation. Firewood collection depletes woody debris, leading to a loss of habitat for specialized organisms. Economical consequences of forest recreation include maintenance costs of recreational infrastructure and diminishing revenues due to visitor-related damage to trees and subsequent reduction in timber quality. In the present thesis I examined the effects of fire place use on the forest soil, including soil microbial biomass and enzyme activity, ground vegetation, shrubs, trees and amount of woody debris. In addition, the reduction in timber value resulting from recreational damage to trees was estimated. In order to develop and implement measures, it is important to find out why forest visitors create and use "wild" fire rings instead of official picnic sites. Therefore, I conducted a forest visitor survey focusing on visitor preferences concerning fire places. An experiment was conducted with four new fire places designed to fulfil forest visitors' requirements, and a follow-up survey documented visitors' reactions. A survey aimed at forestry experts in the whole of Switzerland provided valuable information on foresters' perceptions concerning the consequences of picnicking and grilling and forest recreation in general. At frequently used fire places we found reduced plant species densities in the ground vegetation and shrub layer and changes in plant species composition. Picnicking and grilling also reduced the height and changed the age structure of shrubs and young trees. The amount of woody debris was lower in disturbed plots than in control plots. Soil microbial biomass (Cmic and Nmic) and dehydrogenase activity were differently affected by short- and long-term trampling. In a short-term experiment, these soil characteristics decreased at low and medium, but not at high trampling frequencies. In contrast, the same soil characteristics decreased with increasing trampling intensity in a long-term field survey at fire places that had been in use for more than a decade. The activity of β-glucosidase was only affected by short-term trampling. Phosphomonoesterase activity was most severely affected by long-term trampling, most probably as a result of the loss of plants. The reduction in timber value due to visitor-related damage to trees ranged from 19 to 53 € per hectare and year in two suburban forests. Total recreationinduced costs, i.e. additional expenses and reductions in timber value exceeded 10% of the total annual expenditures of the two forest enterprises examined. The forest visitor survey revealed a preference for fire places near streams, away from forest roads and close to open spaces. While some visitors highly appreciated the well-equipped official sites, others preferred more natural infrastructure with pieces of stones forming a fire ring rather than concrete rims, and logs to sit on instead of benches. Experimental fire places consisting of a ring of stones and logs fulfilled the needs concerning infrastructure of visitors who normally use "wild" sites. However, the location of fire places was termed more important than their infrastructure. Forestry experts' perceptions regarding reasons for "wild" site creation differed largely from the results of the forest visitor survey. According to experts, an insufficient number of barbecue pits, available firewood and forest visitors seeking adventure and romanticism repeatedly lead to the creation of "wild" fire rings

Effects of Fireplace Use on Forest Vegetation and Amount of Woody Debris in Suburban Forests in Northwestern Switzerland

Urban forests are popular recreation areas in Europe. Several of these temperate broad-leaved forests also have a high conservation value due to sustainable management over many centuries. Recreational activities, particularly the use of fireplaces, can cause extensive damage to soil, ground vegetation, shrubs, and trees. Firewood collection depletes woody debris, leading to a loss of habitat for specialized organisms. We examined the effects of fireplace use on forest vegetation and the amount of woody debris by comparing disturbed and control plots in suburban forests in northwestern Switzerland. At frequently used fireplaces, we found reduced species densities in the ground vegetation and shrub layer and changes in plant species composition due to human trampling within an area of 150-200m2. Picnicking and grilling also reduced the height and changed the age structure of shrubs and young trees. The amount of woody debris was lower in disturbed plots than in control plots. Pieces of wood with a diameter of 0.6-7.6cm were preferentially collected by fireplace users. The reduction in woody debris volume extended up to a distance of 16m from the fire ring, covering an area of 800m2 at each picnic site. In order to preserve the ecological integrity of urban forests and to maintain their attractiveness as important recreation areas, we suggest depositing logging residues to be used as firewood and to restrict visitor movements near picnic site

Urban forest usage and perception of ecosystem services – A comparison between teenagers and adults

We thank Christoph Düggelin and Marc Baume for the interpretation of the photographs and two anonymous reviewers for comments on the manuscript. The project was funded by the Swiss State Secretariat for Education, Research and Innovation SERI, Switzerland (Grant No. C13.0135) as a contribution to the COST Action PF1204 and by the Swiss Federal Office for the Environment, Switzerland (Grant No. 16.0074.PJ / S062-1129).Peer reviewedPublisher PD

Luminescent Tris(8-hydroxyquinolates) of Bismuth(III)

Luminescent homoleptic bismuth(III) complexes have been synthesized by adding several functionalized 8-hydroxyquinolate ligands to bismuth(III) chloride in a 3:1 mole ratio in either ethanol or tetrahydrofuran (THF) solvent. These complexes have been characterized by single-crystal X-ray diffraction (XRD) analysis, UV-vis spectroscopy, fluorescence spectroscopy, and density functional theory (DFT) calculations to determine their structures and photophysical properties. Reversible dimerization of the mononuclear tris(hydroxyquinolate) complexes was observed in solution and quantified using UV-vis spectroscopy. The fluorescence spectra show a blue shift for the monomer compared with homoleptic aluminum(III) hydroxyquinolate compounds. Four dimeric compounds and one monomeric isomer were characterized structurally. The bismuth(III) centers in the dimers are bridged by two oxygen atoms from the substituted hydroxyquinolate ligands. The more sterically hindered quinolate complex, tris(2-(diethoxymethyl)-8-quinolinato)bismuth, crystallizes as a monomer. The complexes all exhibit low-lying absorption and emission spectral features attributable to transitions between the HOMO (π orbital localized on the quinolate phenoxide ring) and LUMO (π* orbital localized on the quinolate pyridyl ring). Excitation and emission spectra show a concentration dependence in solution that suggests that a monomer-dimer equilibrium occurs. Electronic structure DFT calculations support trends seen in the experimental results with a HOMO-LUMO gap of 2.156 eV calculated for the monomer that is significantly larger than those for the dimers (1.772 and 1.915 eV). The close face to face approach of two quinolate rings in the dimer destabilizes the uppermost occupied quinolate π orbitals, which reduces the HOMO-LUMO gap and results in longer wavelength absorption and emission spectral features than in the monomer form

How do forest visitors perceive forest management forms? Public acceptance of coppice-with-standards in urban forests

To mitigate climate change consequences, a shift to more renewable energy sources is necessary. The traditional forest management form coppice-with-standards features efficient harvesting cycles and could therefore provide a reliant biomass source. Particularly forests close to urban settlements are popular destinations for outdoor recreation. Therefore, for a well-functioning interaction between recreation and forest management, forest visitors' preferences need to be considered. Even though, coppice-with-standards have been studied scientifically from various points of view, including its cultural and ecological values, little focus was put on the perceived visual attractiveness of this management form. Therefore, this study aims to investigate how forest visitors perceive different forest management forms with a focus on coppice-with-standards in the case study area in Zurich, Switzerland by performing qualitative Go-Along interviews and a quantitative forest visitor survey. The statistical analysis revealed that forest visitors have divided opinions on this management form and prefer even-aged high forest as well as continuous forest management. Therefore, in case of an increasing use of coppice-with-standards management for biomass production, implementation in recreational forests needs to be weighed against less frequently visited areas. However, addressing the visitors with well-targeted communication strategies could result in increased understanding and acceptance and could therefore support the implementation process also in recreational forests

Magnetic Exchange Coupling in the FeIII6(μ6-O) Core: A Hint to the Magnetic Properties of Higher-Nuclearity Spin Clusters

Variable-temperature magnetic susceptibility measurements performed on two hexairon(III) clusters containing a μ6-oxo bridge show that this unusual bridging mode leads to weak antiferromagnetic exchange-coupling interactions between the metal centers, with J(trans) and J(cis) values of 19(2) and 9(1) cm-1, respectively. The result is relevant to the search for magneto-structural correlations in oxo-bridged polyiron aggregates