Projekt DEAL
Refine
Document Type
- Article (9)
Language
- English (9)
Has Fulltext
- yes (9)
Is part of the Bibliography
- yes (9)
Keywords
- Bos taurus; Cervus elaphus; Equus ferus caballus; Fenced pastures; Grazing animals; Interaction behaviour (1)
- Environmental sciences; Physics (1)
- climate change (1)
- cooling (1)
- digital volume correlation (1)
- drought events (1)
- forest canopy (1)
- forest functionality (1)
- grouping behaviour (1)
- historicity (1)
Livestock farming, which produces milk and meat, is practised by nearly all cultures. But in addition to this, grazing livestock fulfils other fundamentally important roles, one of which is the maintenance of open landscapes, which in turn provides habitat for many rare plant and animal species. Whether wild large herbivores, such as red deer (Cervus elaphus), benefit from the management of the open landscapes is unknown, and there are conflicting views on the nature of the interaction between livestock and wildlife. To investigate this question, we studied interactions in space and time between red deer and livestock in an 787 ha fenced pasture in eastern Germany. First, we used faecal pellet counts to determine whether red deer were using the fenced pasture and whether livestock were using the entire available pasture. Second, we fitted ten red deer, as well as eight Konik horses (Equus ferus caballus) and eight Heck cattle (Bos taurus) with GPS-collars. These data allowed us to perform analyses of space–time interactions. The faecal pellet data showed that red deer did indeed use the fenced pasture and that livestock used the entire extent of the pasture. Further, we verified a neutral space–time interaction between red deer and livestock within the pasture. Thus, there was no indication of a negative effect of the presence of livestock on red deer inside the pasture. For these reasons, we recommend that low-intensity grazing by cattle and horses can maintain open landscapes without detrimental effects on the use of the area by red deer.
In human geography and beyond, assemblage thinking has increasingly gained attention as a perspective from which to investigate the emergence and dynamics of more-than-human entanglements. Similarly, in the interdisciplinary field of social-ecological systems analysis, theories of complex adaptive systems have been employed to investigate how social and ecological dynamics and actors interact with each other on different scales. Nonetheless, despite the success of these conceptual perspectives in their respective research fields, there have been few attempts so far to bring these theoretical strands together to explore their common ground and investigate how they could cross-fertilize each other. This contribution seeks to address this gap, by investigating the ontological compatibility of these two approaches and exploring the potential for meaningful syntheses that could be utilized for integrative research—combining perspectives, approaches, and methods taken from social and environmental sciences for the analysis of human-environmental relations. Based on a comparative discussion of four selected “guiding principles” found in assemblage thinking and complex adaptive systems, namely, socio-nature, emergence/historicity, relationality, and self-organization, we find not only significant common ground between the two perspectives but also discrepancies that may be utilized for cross-fertilization. In particular, we argue complex adaptive systems would benefit from a deeper engagement with society-nature theorizations found in the assemblage literature, while assemblage thinking could borrow from complex adaptive systems to broaden its conception of how elements relate to and co-function with each other.
1. Forest management influences a variety of ecosystem structures and processes relevant to meso- and microclimatic regulation, but little research has been done on how forest management can mitigate the negative effects of climate change on forest ecosystems.
2. We studied the temperature regulation capacity during the two Central European extreme summers in 2018 and 2019 in Scots pine plantations and European beech forests with different management-related structural characteristics.
3. We found that the maximum temperature was higher when more trees were cut and canopy was more open. Logging 100 trees per hectare increased maximum temperature by 0.21–0.34 K at ground level and by 0.09–0.17 K in 1.3 m above ground. Opening the forest canopy by 10% significantly increased Tmax, measured 1.3 m above ground by 0.46 K (including pine and beech stands) and 0.35 K (only pine stands). At ground level, Tmax increased by 0.53 K for the model including pine and beech stands and by 0.41 K in pure pine stands. Relative temperature cooling capacity decreased with increasing wood harvest activities, with below average values in 2018 (and 2019) when more than 656 (and 867) trees per hectare were felled. In the pine forests studied, the relative temperature buffering capacity 1.3 m above ground was lower than average values for all sample plots when canopy cover was below 82%. In both study years, mean maximum temperature measured at ground level and in 1.3 m was highest in a pine-dominated sample plots with relatively low stand volume (177 m3 ha−1) and 9 K lower in a sample plot with relatively high stock volumes of Fagus sylvatica (>565 m3 ha−1). During the hottest day in 2019, the difference in temperature peaks was more than 13 K for pine-dominated sample plots with relatively dense (72%) and low (46%) canopy cover.
4. Structural forest characteristics influenced by forest management significantly affect microclimatic conditions and therefore ecosystem vulnerability to climate change. We advocate keeping the canopy as dense as possible (at least 80%) by maintaining sufficient overgrowth and by supporting deciduous trees that provide effective shade.
Comparison of different approaches to estimate bark volume of industrial wood at disc and log scale
(2021)
Within the wood supply chain, the measurement of roundwood plays a key role due to its high economic impact. While wood industry mainly processes the solid wood, the bark mostly remains as an industrial by-product. In Central Europe, it is common that the wood is sold over bark but that the price is calculated on a timber volume under bark. However, logs are often measured as stacks and, thus, the volume includes not only the solid wood content but also the bark portion. Mostly, the deduction factors used to estimate the solid wood content are based on bark thickness. The aim of this study was to compare the estimation of bark volume from scaling formulae with the real bark volume, obtained by xylometric technique. Moreover, the measurements were performed using logs under practice conditions and using discs under laboratory conditions. The mean bark volume was 6.9 dm3 and 26.4 cm3 for the Norway spruce logs and the Scots pine discs respectively. Whereas the results showed good performances regarding the root mean square error, the coefficient of determination (R2) and the mean absolute error for the volume estimation of the total volume of discs and logs (over bark), the performances were much lower for the bark volume estimations only.
Bark characteristics are not only used in the forest-wood supply chain, for example to calculate standing volumes, but also to transform wood volumes and masses. In this study, bark thickness, bark volume and bark mass were analyzed on the basis of 150 Scots pine discs, with a mean diameter of 13 cm. The mean double bark thickness was 3.02 mm, the mean bark volume proportion was 5.6% and mean bark mass proportion was 3.3%. Bark proportions were significantly affected by the log-specific variables ‘diameter over bark’, ‘proportion of bark damage’ and ‘double bark thickness’.
Social-space–time-behaviour has developed very differently (e.g. a, loner, a herd, a pack) in the animal kingdom and depends on many different factors, like food availability, competition, predator avoidance or disturbances. It is known, that red deer are differently distributed in human disturbed areas compared to areas with less anthropogenic influences. But knowledge about the potential influence of human presence on social associations and interactions is rare, albeit differences may result in changing impacts on the environment, such as habitat utilization and feeding damage. Therefore, we investigated differences in the space use and social association of red deer. We studied two radio-collared herds of non-migratory populations in two study areas, which were comparable in landscape structure and vegetation structure, but differed in accessibility for visitors and the extent of their presence. Between the two study sites we compared the home range size, the differences in the extent of home range overlap within each study site and the space–time association (Jacobs Index) of individuals. Additionally, we present data on seasonal variations of home range sizes and social association all year round. In order to compare human activity in the study sites, we used the data from our long-term camera trap monitoring. The herd in the area with more human activity had significantly smaller home ranges and had greater year-round social associations in almost all seasons, except summer. We assume that smaller home ranges and higher association between animals may result in a higher feeding pressure on plants and a patchier utilization in areas with higher disturbances.
Several laboratory studies and experiments have demonstrated the usability of polymer films filled with electrically conductive filler as piezoresistive material. Applied to adhesives, the glue lines of wood products can achieve multifunctional—thus bonding and piezoresistive/strain sensing—properties. Based on critical load areas in timber constructions, upscaled test setups for simplified load situations were designed, especially with regard to a stress-free electrical contact. In a second step, another upscaling was done to small glulam beams. Based on an experimental test sequence, the piezoresistive reactions as well as the behaviour until failure were analysed. The results show in all cases that a piezoresistive reaction of the multifunctionally bonded specimens was measurable, giving a difference in the extent of relative change. Additionally, measured phenomena like inverse piezoresistive reactions, electrical resistance drift and the absence of a piezoresistive reaction were discussed, based on additional strain analysis by digital image correlation. A model of macroscopic and microscopic strains influencing the piezoresistive reaction of the electrically conductive bond line in wood was used to explain all experimental results. Finally, a first scale-up of piezoresistive bond lines from laboratory samples to glulam beams was possible and successful.
Various studies on wood adhesives filled with conductive fillers for future application to structural monitoring showed a piezoresistive (resistance change with strain) response of the adhesive bond lines that is measurable under direct current. The results also showed a relatively high signal noise with low sensitivity. Using impedance spectroscopy as a measurement technique, the improvements in frequency-dependent piezoresistivity over DC (Direct Current) resistography of multifunctional bonded wood were studied. Beech specimens were bonded by one-component polyurethane prepolymer (1C-PUR) filled with carbon black and tested under shear load. The quality of the piezoresistive properties was described by calculating the signal-to-noise ratio (SNR) of the measured signal. A setup-specific frequency band with optimized SNR between 100 kHz and 1 MHz could be derived from the measurements. Several frequencies showed a signal with higher quality resulting in a higher SNR. Regardless of the variations in impedance spectra for all specimens, this frequency band provided several frequencies with improved signal quality. These frequencies give a more reliable signal with lower noise compared to the signal from DC resistography.
Synchrotron-radiation-based microtomography enables the 3D analysis of biological samples in situ beyond simple visualization, providing accurate measurements and recording of temporal data. The microtomography end station at P05 (PETRA III, Hamburg, Germany), operated by the Helmholtz Zentrum Hereon, can accommodate complex sample environments such as a load frame for mechanical testing. Herein, the strain analysis of a volumetric time series dataset of small hardwood samples is presented. For this in situ mechanical testing, the load frame is operated in tensile mode, and the biogenic material samples are subdivided into those specialized for tensile forces and those of regular anatomical structure. Digital volume correlation analysis allows for the prediction of strain development at any position in the sample. The tissue specialized for tensile strength can align dislocations formed under tension such that the deformation is stronger and more ordered. The results show how high-resolution imaging of sequential loading and the subsequent localization of strain can reveal functional morphological relationships. These methods can be extended to other biological materials and may prove to be extremely relevant for the analyses of fibrous and/or layered composite materials.