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  • Open access
  • 72 Reads
Analysis of the changes in the valuable wood market in RDSF Krosno

Timber market is very unusual: despite the fact that it affects the economic behavior of consumers and suppliers, the exchange of goods such as wood is conditioned by the needs and ecological principles of silviculture.

Sale of wood in Poland, due to the dominant position of the State Forests, is supervised by the Office of Competition and Consumer Protection. One of the acceptable forms of wood sale are submissions. Usually, small amounts of wood with unusual features are offered here for a specific group of customers.

Regional Directorate of State Forest (RDSF) Krosno is located in the south-eastern part of Poland and manages a forest area of ​​approximately 400,000 hectares. Annual timber harvesting amounts to approx. 2 million m3, of which less than 2,000 m3 annually is allocated to the submissions.

The paper presents the sale results and prices of veneer wood obtained in submissions and in other forms of timber sale in the territory of the Krosno RDSF in the years 2000−2019.

The presented data, due to their 20-year continuity, make it possible to trace changes in the quantity of wood offered, the species structure, and price trends for individual species against the background of the economic situation in relation to the average prices obtained from other methods of sale.

  • Open access
  • 101 Reads
Comparative evaluation of inspection techniques for decay detection in urban trees

Green areas in cities are acquiring an increasingly important role in urban architecture. However, the central problem associated with urban trees is the need to know and evaluate the health of plants in order to ensure the safety and security of citizens. One important process consists of the technical assessment of health conditions of standing trees, in order to prevent falling due to strength failure or internal damage caused by internal decay. In recent years, investigations with non-destructive techniques on urban trees have shown great success in detecting internal decay, which, depending on the severity of the case, makes the stability of the entire plant or parts of it precarious. This study reports the results of applying an inspection protocol that combines, single-path stress wave timer and resistance micro-drilling, to detect internal defects on sizable Melia trees (Melia azedarach L.) located in the city ​​of Reggio Calabria, Southern Italy. From the trees subsequently felled, a disc was obtained in each test position, which is visually examined. It was found through the data obtained that the non-destructive analyzes carried out with single-path stress waves and resistance measuring drill, correctly identified a defect in the wood even if with different specificity depending on the method used.

  • Open access
  • 151 Reads
Modernized Forest Fire Risk Assessment model based on the case study of three Portuguese Municipalities frequently affected by forest fires

The number of forest fires ignitions has decreased worldwide, thus observing increased levels of intensity and destruction, endangering urban areas, and causing material damages and deaths (Portugal - 2017). Forest fire hazard mapping supported by the surveillance strategy targeted at very susceptible areas with high losses’ potential are the common tools to fire prevention. Each Municipality creates its own Forest Fire hazard map, and so it is observed that along the administrative boundary’s discrepancies occur, even when identical types of landuse are in place. With the evolution of geographic information systems technology sustained by the open-source satellite imagery, along with the innovative Habitat Risk Assessment model of the InVEST software allowed the creation of an easily applicable trans-administrative boundary fire hazard map, with frequent update capabilities and fully open source. This work considered three Municipalities (Tomar, Ourém, and Ferreira do Zêzere) which annually observe various forest fire occurrences. Results enabled a homogeneous Forest Fire Risk Map creation, using landuse, slope, road access network, fire ignitions’ history, visualization basins, and the Normalized Difference Vegetation Index (NDVI) as variables. All variables correlate with each other using different weights, in which the different classes of landuse are considered as habitats and the remaining variables as fire hazard stressors. The results produce a coherent monthly updated Risk Map, which is an alternative to many risk assessment systems used worldwide.

  • Open access
  • 132 Reads
Artificial weathering effect on surface of heat-treated wood of Ayous (Triplochiton scleroxylon K. Shum)

The dark colour obtained with the heat treatment gives the light-coloured wood an attractive appearance, as well as a better behaviour towards thermo-hygrometric variations in the outdoor environment. The heat treatment modifies the wood material by reducing hygroscopicity and consequently promotes greater dimensional stability; it also prolongs the service life of wooden products. The wood characteristics due to weather conditions change over time, particularly the colour, that reflects chemical changes. Natural ageing is usually a relatively slow process, therefore artificial ageing plays an important role to assess the performance by shortening the time compared to natural weathering conditions. The aim of this research is to evaluate the colour and reflectance variation of wooden surfaces due to artificial weathering obtained through a solar box chamber simulating outdoor conditions and subsequent water leaching. A Model 1500E Solar Box (Erichsen Instruments) was used to simulate the exposure to solar radiation and a horizontal shaking agitator with a glass container of distilled water to simulate water leaching.

Untreated and heat-treated samples were used. The thermally modification was conducted on planks of Ayous from Cameroon in an industrial system that used a slight initial vacuum in an autoclave (Maspell WDE Model TVS 6000) and a treatment temperature of 215 °C for three hours. After cutting, the samples were stored in the darkness. To simulate weathering, specimens were subjected to 6 cycles of combined solar box and water leaching. The weathering cycles were performed as follows: first cycle 72 h (3 days) of UV irradiation, followed by 5 h of water leaching; second cycle 168 h (7 days) of irradiation followed by another 5 h cycle of water leaching; third cycle 336 h (14 days) of UV irradiation followed by 5 h of water leaching; fourth cycle 504 h (21 days) of UV irradiation and 5 h of water leaching; fifth cycle 672 h (28 days) of UV irradiation and 5 h of water leaching; and sixth cycle 1008 h (42 days) of UV irradiation and 5 h of water leaching. The solar box chamber is equipped with a 2.5 kW xenon-arc lamp operating at 550 Wm-2, 55°C and UV filter at 280 nm. After each cycle colour was monitored using an X-Rite CA22 reflectance spectrophotometer under the following conditions, according to the CIELAB colour system: illuminant D65, standard observer 10°, geometry of measurement 45°/0°, spectral range 400-700 nm, measurement diameter 4 mm, white reference supplied with the instrument. The points of colour measurement were 30 for each specimen. Three measures were acquired for each point, so that 90 measures were obtained for each specimen. Reflectance of the surface was obtained through the use of an innovative multispectral hypercolorimetric imaging (HMI) technique developed by Profilocolore srl and for the first time applied on wood samples. HMI was performed at time 0 h, 504 h and 1008 h of irradiation and after the water leaching. This imaging technique allowed for obtained calibrated multispectral images, from 300 to 1000 nm, of the entire surface of the specimens that were subsequently processed through the software PickViewer®. The tools of PickViewer® could perform comparison of reflectances and colour coordinates, and PCA on the images, etc. The water, after each cycle of leaching, was also measured for obtaining pH and conductivity values. Moreover, Fourier transform infrared (FTIR) spectroscopy was used to characterize the compound extracted by water leaching.

To summarize the main results, the weathering cycles change significantly the colour of the specimen surface. Solar box irradiation causes darkening of the untreated samples, whereas it causes lightening of the thermally treated ones. On the other hand, the water leaching causes darkening in all cases. With the increase of weathering times, untreated specimen surfaces darken whereas treated specimens lighten so as to tend to have a similar colour or in any case to decrease the chromatic difference that was at the beginning of the weathering tests. The measured values of conductance are higher in the leaching water of untreated specimens and tend to decrease after the first cycles. The values of pH range between 4.00 and 4.52 in both cases (untreated and treated specimens). FTIR spectroscopy demonstrated that water leaching caused loss of materials from the specimens, mainly from those thermally treated. FTIR spectra exhibit signatures of polysaccharides materials as main compounds. Bands of lignin and extractives are also visible. Water leaching seems to remove degraded surface micro-particle of wood.

  • Open access
  • 71 Reads
A survey of potential insect vectors of mountain pine proliferation decline phytoplasma in Curonian Spit, Lithuania.

Mountain pine (Pinus mugo Turra), is a coniferous native to the highlands of central Europe. Our previous study has revealed that mountain pine proliferation decline (MPPD) disease in the Curonian Spit of Lithuania is caused by a ‘Candidatus phytoplasma pini’-related strain (16SrXXI-A). However, the insect vector of MPPD has not been identified. In this study, we conducted a survey to determine potential insect vectors of MPPD phytoplasma for three consecutive years (2016-2019). More than 1,000 insect samples were collected in four locations of the Curonian Spit. These insects were identified as belonging to six families and ten genera. The presence of phytoplasma in insect samples was examined by nested PCR using phytoplasma-specific primers (P1A/16S-SR and F2n/R2). Phytoplasmas were detected in Cinara (Cinara) pini (Scots pine aphid), Cinara (Cinara) piniphila and Cinara (Schizolachnus) pineti (Waxy grey pine needle aphid) insect samples. Subsequent RFLP analysis showed that the PCR-RFLP profile of these positive insect samples was consistent with that of the MPPD of diseased pine trees. These results suggest that C. (C.) pini, C. (C.) piniphila and C. (S.) pineti may be potential insect vectors of MPPD phytoplasma. The findings from this survey will provide useful information for the management of MPPD disease.

  • Open access
  • 111 Reads
Nitrogen fertiliser increases LAI but creates carbon and water costs in Eucalyptus nitens

Leaf area index (LAI) is an important driver of primary productivity, and affects water and nutrient cycling. Extra leaves have both a cost and a benefit to a plant in terms of carbon and water balance and nutrient economics. Greater leaf area increases photosynthetic area, but also incurs a respiratory cost to the plant in terms of leaf construction and maintenance. Optimal leaf area is therefore influenced by the trade-off between carbon gains through photosynthesis and carbon loss through respiration, but is also influenced by transpirational demands. Furthermore, optimal leaf area responds to environmental factors such as nutrition, temperature and water supply. Using three field experiments across a rainfall and temperature gradient in Tasmania, I investigated the way in which nutrient supply influences the optimal leaf area of the globally-important plantation tree, Eucalyptus nitens.

Results show that the costs and benefits of extra leaf area depend on nutrient supply as well as site characteristics. Specifically, LAI was highest at intermediate nitrogen levels over the first growing season, with associated changes to maximum net photosynthetic rate, dark respiration and stomatal conductance. Thus, leaf area response to nutrition is decidedly non-linear in this system with corresponding influences on plant water use and physiology. These results will contribute to the development of efficient nutrition management of production forests through an improved ability to predict and model the impact of fertiliser on productivity.

  • Open access
  • 138 Reads
Anatomy of a perfect storm - Australia’s ‘Black Summer’ forest fires

The 2019/20 forest fires in eastern Australia, referred to as the ‘Black Summer’ fires, burned over 5.8 million hectares of mainly temperate broadleaf forest between September 2019 and February 2020. Twenty-six people lost their lives as a direct consequence of the fires, while bushfire smoke is estimated to have caused 417 excess deaths in the fire-affected regions. Nearly 2,500 homes were lost and widespread damage to infrastructure and livelihoods has severely affected communities and regional economies. The fires killed millions of animals, burned critical habitat of endangered species and large fractions of threatened ecological communities, including significant areas of temperate rain forests. While the true impact of the ‘Black Summer’ fires may never be fully quantified, several formal inquiries have investigated the causes and factors that contributed to the fire season of 2019/20. The final report of the New South Wales Bushfire Inquiry was published in July 2020, with major contributions from the NSW Bushfire Risk Management Research Hub.

Here, I address three questions that have been at the core of the inquiry and the ongoing debate about fire risk management in SE Australia: i) to what extent were the Black Summer fires consistent with historical fire regimes in the region and with fire regimes of temperate forests globally? ii) what was the role of fuel loads versus fuel dryness in preconditioning the landscape for mega forest fires? iii) have fuel reduction treatments been effective in reducing fire extent, severity, or risk to communities?

  • Open access
  • 642 Reads
Taxonomic value of leaf epidermal markers in discriminating some medicinal tree species of Apocynaceae Juss.

Apocynaceae is a useful family comprising of trees notable for different medicinal remedies. Consequent to their importance vis-à-vis scarcity in the forest, they are being sold in various Nigerian markets by herb sellers mostly in sterile and fragmentary forms. Hence, the medicinal plants are subjected to adulteration and substitution. Frequently, identification of the plants by users are basically via floristic markers, which are not readily available for such purpose. It therefore becomes pertinent to carry out the taxonomic revision of these trees to provide additional markers that will contribute to their effective identification for correct use. Various documentations have been made on members of apocynaceae and are properly placed on their respective taxa using epidermal traits. However, such information is scarce for Alstonia boonei, Holarrhena floribunda, Rauvolfia vomitoria, Thevetia nerifolia and Vocanga africana. This study therefore aimed at providing epidermal taxonomic markers that could be employed in delimiting the species as alternative when the fruit or floral parts are wanting. Leaf epidermis of five (5) species of apocynaceae representing 5 genera were studied under a Biological microscope with camera attachment. Data obtained were statistically analyzed. Epidermal cell was Penta or hexagonal in A. boonei and V. africana. Stomatal length varied from 20.88 µm (R. vomitoria) to 25.92 µm (T. nerifolia) and 18.96 µm (R. vomitoria) to 29.28 µm (V. africana) on the abaxial and adaxial layers respectively. All the epidermal characters on the adaxial layer were significantly different (p<0.05) among the species. Anticlinal walls were sinuated in H. floribunda and T. nerifolia while in R. vomitoria, it was straight to wavy. V. africana and A. boonei anticlinal walls were straight. This study represents the first account of epidermal characterization of the members of apocynaceae in Nigeria and are of taxonomic importance in setting boundaries among the species.

  • Open access
  • 40 Reads
The lessons of Scots pine forest decline in Ukraine

The condition of Ukraine's forests has deteriorated sharply since the 2009 drought. Over 10 years, the area of Scots pine stands decline has increased 2.3 times. The purpose of the research was an integration of published and own data on the spatial & temporal dynamics of Scots pine forest decline with the contribution of bark beetles and pointing the ways for mitigating this process. The reference materials regarding the forest stands characteristics, forest health, weather, as well as the results of own field and laboratory research (forest inspection, laboratory rearing the bark beetles in branches, evaluation of parameters) were the data sources. Ips acuminatus (Gyllenhal, 1827): Coleoptera: Curculionidae: Scolytinae was the first bark beetle to infest the stands weakened in a result of climate change and anthropogenic pressure, including forest management. Pure pine stands over 70 years old were infested first. The relative density of stocking by itself is a less important risk factor than its sudden decrease by thinning or clear felling of the neighboring stands. The predominant development of outbreaks of drying out in Polesie (Forest zone) is associated with a large proportion of pure pine plantations of the same age, untimely thinning, and relatively slow drying of felling residues (in comparison with the Forest-Steppe), in which the bark beetle has time to complete its development. The algorithm for prediction of bark beetles foci spread was developed. It will help to upgrade the accuracy of prediction, to evaluate the optimal area of survey and control measures against insect pests. Recommendations for improving the forestry regulatory framework have been developed.

  • Open access
  • 194 Reads
Different temperature and humidity responses to the clear-cut and the gap in a Scots pine forest: a study case in Central Poland

Over the past decades, relatively few experimental studies have been carried out in which the micrometeorological conditions have been studied over different small clearings plots of the forest. As these conditions can significantly affect many processes in the ecosystem, two questions arise: 1) whether and how the microclimatic conditions differ in the small clear-cut and the gap, and 2) how heterogeneous is the distribution of these conditions on these plots. The aim of the study was to determine the spatial variation of air temperature on the clear-cut and gap as well as to compare the distribution of thermal and humidity conditions on both areas. The research was carried out in Central Poland on a clear-cut with a width of 60 m and on a gap of an ellipsoid shape (40x70 m). The measurements were carried out in two series: spring-summer, in the period when the height of the sun during the day conditioned inflow of direct solar radiation to any surface (May–August 2006), and autumn, when direct radiation was limited by neighbouring stands (October­–November 2006). Average values of air temperature on the gap in the spring-summer period differed in individual parts of 2.2 oC, while on the clear-cut by 1.0 oC. In the autumn, thermal diversity on both research plots was similar (average 0.8 oC). The thermal diversity within the research areas was particularly marked in the case of extreme air temperature values. We found the modest spatial diversification of humidity parameters: vapour pressure, relative humidity, and humidity deficit. Particularly large diversification of relativity humidity and vapour pressure deficit were claimed in spring-summer period in the situation of heat waves. The least beneficial thermal and humidity conditions for plants growing occurred in the north-east parts of clear-cut and gap, that is why it necessary to take particular note of these locations during undertaking the silviculture.