Articles containing the keyword 'weather'

There is no doubt that tree survival, growth, and reproduction in North America's boreal forests would be directly influenced by the projected changes in climate if they occur. The indirect effects of climate change may be of even greater importance, however, because of their potential for altering the intensity, frequency, and perhaps even the very nature of the disturbance regimes which drive boreal forest dynamics. Insect defoliator populations are one of the dominating disturbance factors in North America's boreal forests and during outbreaks trees are often killed over vast forest areas. If the predicted shifts in climate occur, the damage patterns caused by insects may be considerably changed, particularly those of insects whose temporal and spatial distributions are singularly dependent on climatic factors. The ensuing uncertainties directly affect depletion forecasts, pest hazard rating procedures, and long-term planning for pest control requirements. Because the potential for wildfire often increases in stands after insect attack, uncertainties in future insect damage patterns also lead to uncertainties in fire regimes. In addition, because the rates of processes key to biogeochemical and nutrient recycling are influenced by insect damage, potential changes in damage patterns can indirectly affect ecosystem resilience and the sustainability of the multiple uses of the forest resource.

In this paper, a mechanistic perspective is developed based on available information describing how defoliating forest insects might respond to climate warming. Because of its prevalence and long history of study, the spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), is used for illustrative purposes in developing this perspective. The scenarios that follow outline the potential importance of threshold behaviour, historical conditions, phenological relationships, infrequent but extreme weather, complex feedbacks, and natural selection. The urgency of such considerations is emphasized by reference to research suggesting that climate warming may already be influencing some insect lifecycles.

• Fleming, E-mail: rf@mm.unknown

The Värriö environmental measurement station has been designed and constructed during 1991 and 1992. The measurement system consists of measurement units for gases (sulphur dioxide, ozone, carbon dioxide), particles, photosynthesis and irradiation. A meteorological station is also included. The preliminary measurement period was started on August, 1991. During the first year (1991–1992) some parts of the system were redeveloped and rebuilt. Full, continuous measurement started in August 1992. The system has been working quite reliably, with good accuracy. The preliminary results show that pollution episodes are observed when the wind direction is from Monchegorsk or Nikel, the main emission sources in Kola Peninsula.

• Hari, E-mail: ph@mm.unknown
• Aalto, E-mail: pa@mm.unknown
• Hämeri, E-mail: kh@mm.unknown
• Kulmala, E-mail: mk@mm.unknown
• Lahti, E-mail: tl@mm.unknown
• Luoma, E-mail: sl@mm.unknown
• Palva, E-mail: lp@mm.unknown
• Pohja, E-mail: tp@mm.unknown
• Pulliainen, E-mail: ep@mm.unknown
• Siivola, E-mail: es@mm.unknown
• Vesala, E-mail: tv@mm.unknown

Snow and rime, attached to branches of conifers, seriously damaged forests in a region of 11,000 km² in Southern Finland during a passage of two nearly occluded cyclones in 1959. The roles of different weather elements were studied by considering the variations occurring in them over this region and its surroundings. Damage occurred only inside an accentuated pattern of copious orographic precipitation. Precipitation only became attached to and retained on branches in such parts of the area where temperature varied on both sides of freezing point but did not exceed 0.6°C. Furthermore, damage only occurred in forests where rime formed (above a certain level and on sloping towards the prevailing wind).

The PDF includes a summary in English.

• Solantie, E-mail: rs@mm.unknown
• Ahti, E-mail: ka@mm.unknown

Discoloration of the sapwood caused by blue-stain fungi on conifer logs during interim storage causes significant loss to the forest industry. The fungal infection is often associated with bark beetle attacks because the spores are transmitted by the beetles. They can also be disseminated by rain-splash and moist air. While there are methods to protect logs from sap-stain in wood yards, this is often not possible in the forest for practical and regulatory reasons. Timing of harvesting and timely transportation are often the only ways to prevent blue-stain. To estimate the urgency of transportation, knowledge of the growth of blue-stain fungi and its dependence on weather conditions is of great interest.   The proportion of discolored sapwood on Norway spruce logs was recorded along a time series, together with weather data in two field experiments conducted in spring and summer at two alpine sites in Austria. A predictive model was developed to estimate the proportion of blue-stained sapwood based on the temperature sum to which the logs were exposed. After harvest in March, there was a time lag of 82 and 97 days at the two respective sites, caused by initially low temperatures, before discoloration started. In contrast, sap-stain occurred 14 days after the harvest in June, when warm conditions prevailed from the start. The nonlinear least square regression model can help to estimate a window of opportunity to transport wood before it loses its value and serves as a sub model for lead time estimation within logistic decision support systems.

• Böhm, Department of Forest and Soil Sciences, Institute of Forest Engineering, University of Natural Resources and Life Sciences, Vienna (BOKU), Peter-Jordan-Strasse 82, 1190 Vienna, Austria https://orcid.org/0000-0001-7803-6618 E-mail: stephan.boehm@boku.ac.at
• Baier, Department of Forest and Soil Sciences, Institute of Forest Entomology, Forest Pathology and Forest Protection, University of Natural Resources and Life Sciences, Vienna (BOKU), Peter-Jordan-Strasse 82, 1190 Vienna, Austria https://orcid.org/0000-0002-1029-5637 E-mail: peter.baier@boku.ac.at
• Kirisits, Department of Forest and Soil Sciences, Institute of Forest Entomology, Forest Pathology and Forest Protection, University of Natural Resources and Life Sciences, Vienna (BOKU), Peter-Jordan-Strasse 82, 1190 Vienna, Austria https://orcid.org/0000-0002-9918-3593 E-mail: thomas.kirisits@boku.ac.at
• Kanzian, Department of Forest and Soil Sciences, Institute of Forest Engineering, University of Natural Resources and Life Sciences, Vienna (BOKU), Peter-Jordan-Strasse 82, 1190 Vienna, Austria https://orcid.org/0000-0002-1198-9788 E-mail: christian.kanzian@boku.ac.at

This study’s aim was to calculate the weathering rates of Ca and Mg for five boreal forest soils in southern Finland on granitic and gabbro containing bedrock. The effect of mineralogy on the total concentrations of Ca and Mg in soil and weathering rates was evaluated. The aim was also to estimate the effect of mechanical soil disturbance related to ploughing on the weathering in the gabbro area. The total concentrations of SiO₂, CaO, MgO, and Zr were determined by XRF, and weathering rates of Ca and Mg were determined based on the changes in the CaO, MgO, and Zr concentrations. The weathering rates of Ca+Mg varied 5–38 mmol_c m^–2 year^–1 in the E+B/BC horizons among the plots. Soil disturbance related to ploughing increased the weathering of Ca and Mg largely in the disturbed part of the topmost mineral soil as indicated by the decreasing concentrations of Ca and Mg after mechanical soil disturbance. The weathering input of Ca in the undisturbed soil did not fully replace the Ca output in final whole-tree cutting. The weathering input of Mg in the undisturbed soil was sufficient to replace the lost Mg in stemwood harvesting but not on all the plots the lost Mg in whole-tree harvesting. Weathering rates were higher in the gabbro than the granitic areas.

• Lindroos, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: antti.lindroos@luke.fi
• Ilvesniemi, Natural Resources Institute Finland (Luke), Production systems, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: hannu.ilvesniemi@luke.fi

In wintertime, the payload capacity of a timber truck is reduced by snow that accumulates on the structures of the truck. The aim of this study was to quantify the potential payload loss due to snow and winter accessories and to predict the loss with weather variables. Tare weights of eight timber trucks were collected at mill receptions in Finland over a one-year period. Monthly and annual loss of potential payload was estimated using the tare measurements in summer months as a reference. Each load was also connected with weather data at the location and time of delivery and payload loss explained by the weather data with the aid of regression models. The maximum loss of payload varied between 1560 kg and 3100 kg. On a monthly basis, the highest losses occurred in January, when the median values varied between 760 kg and 2180 kg. Over the year, the payload loss ranged between the trucks from 0.5% to 1.5% (from 1.9% and 5.1% in January) of the total number of loads in the study. Payload loss was found to increase with decreasing temperature, increasing relative humidity and increasing precipitation. Although the average payload loss was not very high, the biggest losses occur just during the season of highest capacity utilization. Big differences were also found in the tare weights between the trucks. The results of the study give incentive to develop truck and trailer structures that reduce the adherence of snow.

• Anttila, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0002-6131-392X E-mail: perttu.anttila@luke.fi
• Nummelin, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: tuomas.nummelin@luke.fi
• Väätäinen, Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: kari.vaatainen@luke.fi
• Laitila, Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0003-4431-3319 E-mail: juha.laitila@luke.fi

Fast-growing hybrids of Populus L. have an increasing importance as a source of renewable energy and as industrial wood. Nevertheless, the long-term sensitivity of Populus hybrids to weather conditions and hence to possible climatic hazards in Northern Europe have been insufficiently studied, likely due to the limited age of the trees (short rotation). In this study, the climatic sensitivity of ca. 65-year-old hybrid poplars (Populus balsamifera L. × P. laurifolia Ledeb.), growing at two sites in the western part of Latvia, and ca. 55-year-old hybrid aspens (Populus tremuloides Michx. × P. tremula L.), growing in the eastern part of Latvia, have been studied using classical dendrochronological techniques. The high-frequency variation of tree-ring width (TRW) of hybrid poplar from both sites was similar, but it differed from hybrid aspen due to the diverse parental species and geographic location of the stands. Nevertheless, some common tendencies in TRW were observed for both hybrids. Climatic factors influencing TRW were generally similar for both hybrids, but their composition differed. The strength of climate-TRW relationships was similar, but the hybrid poplar was affected by a higher number of climatic factors. Hybrid poplar was sensitive to factors related to water deficit in late summer in the previous and current years. Hybrid aspen was sensitive to conditions in the year of formation of tree-ring. Both hybrids also displayed a reaction to temperature during the dormant period. The observed climate-growth relationships suggest that increasing temperatures might burden the radial growth of the studied hybrids of Populus.

• Šēnhofa, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: silva.senhofa@gmail.com
• Zeps, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: martins.zeps@silava.lv
• Matisons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
• Smilga, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: janis.smilga@silava.lv
• Lazdiņa, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: dagnija.lazdina@silava.lv
• Jansons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv

• Drobyshev, SUFOR Project, Department of Plant Ecology and Systematics, Ecology Building, Sölvegatan 37, Lund University, SE-223 62 Lund, Sweden E-mail: igor.drobyshev@ekol.lu.se
• Niklasson, SUFOR Project, Southern Swedish Forest Research Centre, SLU, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: mn@nn.se
• Angelstam, Grimsö Wildlife Research Station, Department of Conservation Biology, Forest Faculty, SLU, SE-730 91 Riddarhyttan, Sweden E-mail: pa@nn.se

Forest fire is one of the natural disturbances, which have important ecological and socioeconomical effect. Although fire activity is driven by weather conditions, during past two centuries forest fires have been strongly anthropogenically controlled. In this study, teleconnection between sea surface temperature (SST) in the Atlantic, which influences climate in Europe, and forest fire activity in Latvia and Estonia was assessed using “Climate explorer” web-tool. Factors affecting number and area of forest fires in Latvia and Estonia differed, suggesting regional specifics. In Estonia, the number of fires correlated with the SST in the North Atlantic in spring and summer, which affects the inflow of cool and dry air masses from the Arctic, hence the aridity and burnability. The area of fires in Estonia and in Latvia was associated with increased SST in Baltic Sea and near the European coast in summer, which likely were consequences of occurrence of warm high-pressure systems in summer, causing hot and dry conditions. Nevertheless, the observed teleconnections could be used to predict activity of forest fires in Latvia and Estonia.

• Kitenberga, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 E-mail: mara.kitenberga@gmail.com
• Matisons, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
• Jansons, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv
• Donis, Latvian State Forest Research Institute ‘Silava’, Rigas st. 111, Salaspils, Latvia, LV2169 E-mail: janis.donis@silava.lv