Search the repository

A+ | A- | | SLO | ENG

Abstract: Forest microclimate is strongly affected by local topography and management activities, as these directly alter overstory structure. In the present work we analysed the dependence of observed patterns of spatio-temporal microclimatic variations on topographic, canopy- and management-related factors. A forestry experiment was conducted in managed fir-beech forests in the Dinaric Mountains (Slovenia), which are characterized by rugged karstic terrain with numerous sinkholes. In 2012, cutting treatments representing a range in the intensity of overstory removal were performed: uncut controls (CON), 50% cut of stand growing stock (intermediate management intensity % IMI) and 100% cut (high management intensity % HMI) creating 0.4 ha canopy gaps. Fine-scale variation in aspect and slope and its effects on microclimate was assessed by comparing central, south-facing and north-facing within-sinkhole positions. We measured microclimatic variables (air temperature % T, relative humidity % RH) 0.5 m above the ground over three consecutive post-treatment growing seasons. Microclimatic variables showed an increase (T and vapour pressure deficit % VPD) or decrease (RH) with management intensity. Daily Tmax and VPDmax in HMI treatment were up to 5.9°C (on average 3.5°C) and up to 1.4 kPa (on average 0.6 kPa) higher than those in CON treatment, respectively, whereas daily RHmin was up to 22.7 (on average 13.0) percentage points lower. Regarding intra-seasonal patterns, microclimatic differences between treatments were largest during the summer. South-facing plots in the HMI treatment overall exhibited the most extreme conditions, i.e. the highest Tmax and lowest RHmin. Differences in microclimate between treatments were strongly modulated by canopy cover. The results also suggest that overstory removal increases topography-mediated variation in microclimate, as evidenced by significant differences in T, RH and VPD along the fine-scale topographic gradient within the created canopy gaps.
Keywords: tree cutting, air temperature, relative humidity, vapour pressure deficit, karst topography, canopy cover
Published in DiRROS: 08.10.2020; Views: 1310; Downloads: 554
Full text (1,59 MB)
This document has many files! More...

Abstract: The paper treats the processes involved in wood densification and provides a summary of the state-of-the-art, as presented in the literature, with regard to densification as achieved by compression, accompanied by some form of hydrothermal treatment. The viscoelastic nature of wood is discussed, togetherwith its thermal softening and typical stress-strain relationships. The properties of densified wood products depend, apart from processing parameters, on various anatomical features such as density, the percentage of late wood material, ray volume and the loading direction. The problems associated with wood stabilization after densification are also treated. Relevant examples of wood densification from fundamental research, and the results of applied studies significant for everyday practice, are presented. Aspecial focus is given on the process of viscoelastic thermal compression (VTC) of wood.
Keywords: wood, densification, softening, transverse compression, viscoelasticity, glass transition temperature
Published in DiRROS: 12.07.2017; Views: 4155; Downloads: 1901
Full text (476,08 KB)

Keywords: Cenangium dieback of pines, forest dieback, fungi, Cenangium ferruginosum Fr., temperature, moisture, growth medium
Published in DiRROS: 12.07.2017; Views: 4325; Downloads: 1856
Full text (658,38 KB)

Abstract: Temperature has critical impact on food quality and safety within food supply chain, therefore, food should be kept at the defined storage temperature range. Final consumer should be assured when buying food about actual temperature and thermal history of the selected food product and this is why it should be indicated on the packed or prepacked item. The chromogenic temperature indicator for cold food chain was prepared from suitable active material packed in the properly structured holder. When temperature rises above the defined storage temperature, the active material changes colour and physical state (solid/liquid). Simultaneously, special packaging structure enables irreversible recording of the time exposed to the elevated temperature. The active material was made of thermochromic composite, consisting of dye, developer and solvent. It changes colour at its melting point, being coloured below and discoloured above it. The temperature is called activation temperature of the composite. Its value was adjusted by appropriate solvent and additives used for preparation of the composite, to reach the desired value. The temperature dependent colour change of the composite was determined by colorimetric measurements. The conditions for best observation of the change by naked eye were also examined. The structure of the active material’s holder was analyzed for best displaying of the time spend at high temperature (above the activation temperature). Functioning of the indicator was examined with growth of pathogens as a function of migration of the active material at temperature above the required storage temperature of the food. It was found out that the described chromogenic temperature indicator for cold food chain shows the thermal history of food storage by colour-, phase- and migration changes of the active composite material and consequently would be reliable as indicator in cold food chain to indicate temperature abuse and would disclose potential growth of psychrophilic microorganisms.
Keywords: Chromogenic temperature indicator, Food cold chain, Food quality and safety, Temperature control, Thermal history
Published in DiRROS: 16.12.2014; Views: 6171; Downloads: 945
Link to full text