Articles containing the keyword 'changes'

This paper analyses the potential of utilizing a previously existing infrastructure of small sawmills in a backward area to enhance planned social development, considering at the same time both social and economic objectives. The paper presents the case of a rural forest region of 352,000 ha in Southern Chile in the period 1970–73. It is concluded that meaningful contributions can be made by this traditional industry to such development.

The PDF includes a summary in Finnish.

• Saravia, E-mail: fs@mm.unknown

The seasonal changes of the roots systems of a pine stand on the peatlands have been studied with samples collected during summers 1952-1954 and winter 1955. There are altogether seven sample areas that are located in the district of Korkeakoski.  

The amount of roots is at the smallest in the spring, increasing then rapidly and peaking at the end of July. After that the amount of roots decreases again against the winter to the same size than in the spring. Variations seem to be similar in every year and also similar to other studies on mineral soils.

The PDF contains a summary in Finnish. 

• Heikurainen, E-mail: lh@mm.unknown

Spectral characteristics of rapid changes in forest and the spectral separability of change categories were studied through the analysis of satellite scanner images. A computational model of the spectral reflectance of a Scots pine (Pinus sylvestris L.) stand as a function of time was constructed and compared with empirical data. The study area, centred at 61°51’ N, 24°22’ E, was located in boreal forest in Southern Finland. Ground truth data consisted of forest stands and sample plots. Spectral data comprised multitemporal Landsat Thematic Mapper and Spot images as well as spectroradiometer measurements. The separability of the changes was tested with statistical tests and classifications. The separability varied according to the change category. A scheme for fully automated change monitoring system was presented.

The PDF includes a summary in Finnish.

• Häme, E-mail: th@mm.unknown

Biogeographical patterns of the Scolytidae in Fennoscandia and Denmark, based on species incidence data from the approximately 70 km x 70 km quadrats (n = 221) used by Lekander et al. (1977), were classified to environmental variables using multivariate methods (two-way indicator species analysis, detrended correspondence analysis, canonical correspondence analysis).

The distributional patterns of scolytid species composition showed similar features to earlier presented zonations based on vegetation composition. One major difference, however, was that the region was more clearly divided in an east-west direction. Temperature variables associated with the location of the quadrat had the highest canonical coefficient values on the first axis of the CCA. Although these variables were the most important determinants of the biogeographical variation in the beetle species assemblages, annual precipitation and the distribution of Picea abies also improved the fit of the species data.

Samples with the most deviant rarity and typicality indices for the scolytid species assempblages in each quadrat were concentrated in several southern Scandinavian quadrats, in some quadrats in northern Sweden, and especially on the Swedish islands (Öland, Gotland, Gotska Sandön) in the Baltic Sea. The use of rarity indices which do not take the number of species per quadrat, also resulted high values for areas near Stockholm and Helsinki with well-known faunas. Methodological tests in which the real changes in the distribution of Ips acuminatus and I. amitinus were used as indicators showed that the currently available multivariate methods are sensitive to small faunal shifts even, and thus permit analysis of the fauna in relation to environmental changes. However, this requires more detailed monitoring of the species’ distributions over longer time spans.

Distribution of seven species (Scolytus intricatus, S. laevis, Hylurgops glabratus, Crypturgus cinereus, Pityogenes salasi, Ips typographus, and Cyleborus dispar) were predicted by logistic regression models using climatic variables. In spite of the deficiencies in the data and the environmental variables selected, the models were relatively good for several but not for all species. The potential effects of climate change on bark beetles are discussed.

The PDF includes a summary in Finnish.

• Heliövaara, E-mail: kh@mm.unknown
• Väisänen, E-mail: rv@mm.unknown
• Immonen, E-mail: ai@mm.unknown

The effects of modern forestry on northwest European forest invertebrates are summarized and analysed mainly on the basis of published literature. The direct influence of different practices including clear-cutting, thinning, burning-over, ploughing, changes in tree species composition of stands, fertilization, insecticides, pheromones and biological control are discussed from a forest zoological point of view. Also, the indirect effects of general changes in boreal forest dynamics, loss of primeval forests, cessation of natural fires and the dominance of young stands are described. The direct effects of different silvicultural practices on the species composition and diversity of forest invertebrates are usually considered to be striking but transient. However, when large areas are treated, the species associated with primeval forests, especially with the wood composition system in them, as well as the species associated with fires, seem to have drastically declined. In northwest Europe, efficient forestry has not caused such serious pest problems as is known from tropical countries or North America.

The PDF includes a summary in Finnish.

• Heliövaara, E-mail: kh@mm.unknown
• Väisänen, E-mail: rv@mm.unknown

An investigation into the aerial distribution of Fomes annosus (now Heterbasidion annosum) in Finland was carried out. Prevalence of the fungus in the air was estimated from cultural counts of mycelia produced by diaspores which had fallen onto spruce discs and agar plates. The influence of climate on deposition of diaspores was determined from weather recordings.

For the main study, F. annosus diaspores collected from spruce stands in Helsinki, Anjala and Jokioinen were recorded at weekly or fortnightly intervals throughout 1968. Diaspores fell during the 24-hour periods almost continuously at all three observation sites from April to November, but the deposition was most frequent from late May to the end of October. The amounts of deposition varied greatly with the observation sites, seasons of the year, and time of the day. The fall was heaviest at Anjala and slightest at Jokioinen.

Throughout the season of deposition, more diaspores were trapped on all observation sites at night than during the day. A significant positive correlation was found between the fall of F. annosus diaspores and the air temperature. Diaspores of F. annosus were found in the forest on needles and leaves, and underneath the humus layer in mineral soil. The fall of diaspores decreased as the distance from sporophores increased.

The aerial distribution of two antagonists to F. annosus, viz. Peniophora gigantea and Trichoderma viride, was also studied. It was found that the diaspores of the former fell mainly during the same seasons as those of F. annosus.

• Kallio, E-mail: tk@mm.unknown

Silver birch (Betula pendula Roth) is classified in diffuse-porous wood category. In this case structure of wood tissue is quite similar across whole cross-sectional area. The aim of this study was to analyse cross-section variability of moisture content (MC) of growing silver birch wood, significant hardwood species in Polish forests. Investigations were performed on 120 model trees. In the trunk of each model tree, an increment core was collected at breast height. Samples were collected of 30 different trees in four different seasons. The greatest MC was observed during winter, lowest MC in summer. Differences in MC were statistically significant only between winter versus spring, summer, and autumn. Distribution of MC on cross-section was similar in each season. The greatest average value was observed close to pith, then it was decreasing in bark direction. The greatest difference between observed in spring – 19.51% (p < 0.05) and lowest in autumn – 4.66%. Distribution of green density (GD) on cross section was inverse proportional to MC value. Variations in GD and MC are relevant for log transport planning, weight-scaling systems, lumber drying and dynamic assessment of stiffness. Therefore, from an environmental loss perspective, it is important to determine changes in MC and GD across the year.

• Tomczak, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0001-5192-0294 E-mail: karol.tomczak@up.poznan.pl
• Arkadiusz, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0003-1140-8282 E-mail: arkadiusz.tomczak@up.poznan.pl
• Naskrent, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0002-0756-4162 E-mail: bartlomiej.naskrent@up.poznan.pl
• Jelonek, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0001-9558-9951 E-mail: tomasz.jelonek@up.poznan.pl

In the southwestern pre-Saharan arid zone of Morocco, the endemic argan forest (Argania spinosa) had been almost completely destroyed in the 1960s due to intensive coal mining and mixed cereal-livestock farming. These activities turned out to be unviable and a massive rural exodus occurred in the 1970s. Local populations started to develop maintenance-free prickly pear (Opuntia ficus-indica) cultivation at large scale in order to keep their land ownership rights, while reducing their traditional agropastoral activity. We conducted a survey in order to characterize the relationships between the age of prickly pear orchards and argan tree regeneration. We also explored facilitating factors, such as soil organic matter and mycorrhiza. Results showed a high positive correlation (r² = 0.75, p < 0.001) between the age of prickly pear orchards and argan tree resprouts, but with differences depending on a continentality gradient. The soil organic matter content also showed highly significant differences (p < 0.001) depending on the age of the prickly pear plantation, while spora density did not show such differences. The recent high economic value attributed to prickly pear fruits, and to both argan and prickly pear seed oil, has given farmers the opportunity to develop a lucrative agricultural activity, while promoting the recovery of native vegetation. This situation constitutes a remarkable example of speculative agricultural development in a very harsh environment, in phase with ecological priorities for combating desertification. It could represent an alternative to the externally-generated projects sustained by high levels of public funding, with ecological, economic and social impacts which are sometimes questionable.

• Genin, Institut de Recherche pour le Développement (IRD) & Aix-Marseille Université, Laboratoire Population, Environnement, Développement, UMR151 AMU-IRD, Marseille, France E-mail: miguel.genin@gmail.com
• Alifriqui, Cadi Ayyad University (UCAM), Laboratoire d’Ecologie et Environnement (CNRST, URAC 32), Faculté des Sciences Semlalia, Marrakech, Morocco E-mail: alifriqui@gmail.com
• Fakhech, Cadi Ayyad University (UCAM), Laboratoire d’Ecologie et Environnement (CNRST, URAC 32), Faculté des Sciences Semlalia, Marrakech, Morocco E-mail: abdessamad.fakhech@edu.uca.ac.ma
• Hafidi, Cadi Ayyad University (UCAM), Laboratoire d’Ecologie et Environnement (CNRST, URAC 32), Faculté des Sciences Semlalia, Marrakech, Morocco E-mail: hafidi.ucam@gmail.com
• Ouahmane, Cadi Ayyad University (UCAM), Laboratoire d’Ecologie et Environnement (CNRST, URAC 32), Faculté des Sciences Semlalia, Marrakech, Morocco E-mail: l.ouahmane@gmail.com
• Genin, Institut de Recherche pour le Développement (IRD) & Aix-Marseille Université, Laboratoire Population, Environnement, Développement, UMR151 AMU-IRD, Marseille, France E-mail: didier.genin@univ-amu.fr

• Ripatti, Finnish Forest Research Institute, Helsinki Research Centre, Unioninkatu 40 A, FIN-00170 Helsinki, Finland E-mail: pekka.ripatti@metla.fi