Search results for "picea"
showing 10 items of 113 documents
Density-dependent vole damage in silviculture and associated economic losses at a nationwide scale
2009
Voles inflict damage to silviculture by debarking or severing tree seedlings. The large-scale impacts of vole damage to silviculture, both in terms of severity and financial losses are, however, poorly known. In autumn 2005, cyclically fluctuating vole populations were at their highest in Finland for over 15 years, which led to extensive damage to silviculture during the winter 2005/06. We carried out a nationwide assessment of the incidence, spatial extent and economic value of damage and its relation to vole abundance in privately owned forests during this winter. Damage data were obtained with a questionnaire addressed to the directors of all Forest Management Associations (FMAs) operati…
Egle
2021
Egle (Picea sp.) ir ziemeļu puslodē plaši izplatīts augs. Pasaulē ir aptuveni 50 egļu sugu, bet Latvijā savvaļā aug tikai vien no tām. Apstādījumos gan sastopamas arī introducētas sugas. LU Muzeja Botānikas un mikoloģijas kolekcijās glabājas gan egļu herbāriji, gan to čiekuri. Ekspozīcijā “Čiekuri” ir pārstāvētas 12 egļu sugas no visas pasaules.
1-Aminocyclopropane-1-Carboxylic Acid, its Malonyl Conjugate and 1-Aminocyclopropane-1-Carboxylate Synthase Activity in Needles of Damaged and Undama…
1994
Summary Levels of free 1-aminocyclopropane-1-carboxylic acid (ACC), its malonyl conjugate (MACC) and ACC-synthase activity were significantly higher in the needles of damaged Norway spruce trees ( Picea abies (L.) Karst ) compared with those in undamaged trees during both the diurnal and seasonal courses. The concentrations of ACC and MACC, and ACC-synthase activity fluctuated much more intensively in the needles of damaged trees both in the diurnal and the seasonal courses than in those of undamaged ones, which implies that damaged trees respond more sensitively to the environmental conditions. ACC concentrations were the highest in summer and lowest in fall, while MACC concentrations seem…
Koksnes pelnu ietekme uz biogēno elementu saturu parastās egles Picea abies skujās
2018
Darba izstrādes laikā veikta parastās egles (picae abies) skuju biogēno elementu satura noteikšana un analizēšana pirms un pēc mēslošanas ar koksnes pelniem, kā arī augsnes un pelnu biogēno elementu satura noteikšana un analizēšana pirms mēslošanas.Pelnu mēslošanas izmēģinājumi ierīkoti 2014. gadā četrās vidēja vecuma parastās egles audzēs. Audzes pēc meža tipiem iedalāmas platlapju kūdrenī un damaksnī. Ievāktas pēdējā gada, jeb jaunākas koka skujas. Skujas ievāktas 2014., 2015. un 2018. gadā. Augsnes paraugi ņemti katrā audzē, divās vietās, ziemeļu un dienvidu virzienā noteiktos dziļumos (O horizonts, 0-10 cm, 10-20 cm, 20-40 cm un 40-80 cm), ar augsnes zondes palīdzību.Biogēnās vielas sku…
Changes in Levels of a-Tocopherol and Ascorbate in Spruce Needles at Three Low Mountain Sites Exposed to Mg2+-Deficiency and Ozone
1994
The main objective of this study was the com parison of changes in levels of α-tocopherol and ascorbate in needles of spruce trees with various degrees of damage at three low mountain sites. The ascorbate content in needles of spruce trees with various degrees of dam age differs in the course of seasons as well as in the absolute level. The antioxidant status was affected mainly during summer. The content of ascorbate in needles of dam aged trees was significantly increased compared to that of undamaged trees. Despite seasonal and daily fluctuations, the level of ascorbate seems to be a good indicator for the degree of dam age in the case of symptoms described as montane yellowing. Together…
Toxicological and bioactivity evaluation of blackcurrant press cake, sea buckthorn leaves and bark from Scots pine and Norway spruce extracts under a…
2021
Aqueous extracts from blackcurrant press cake (BC), Norway spruce bark (NS), Scots pine bark (SP), and sea buckthorn leaves (SB) were obtained using maceration and pressurized hot water and tested for their bioactivities. Maceration provided the extraction of higher dry matter contents, including total phenolics (TPC), anthocyanins, and condensed tannins, which also impacted higher antioxidant activity. NS and SB extracts presented the highest mean values of TPC and antioxidant activity. Individually, NS extract presented high contents of proanthocyanidins, resveratrol, and some phenolic acids. In contrast, SB contained a high concentration of ellagitannins, ellagic acid, and quercetin, exp…
Detection and evaluation of an early divergence problem in northern Fennoscandian tree-ring data
2013
Although not yet fully understood, reduced sensitivity of tree growth to temperature at high northern latitudes during the last ˜ 40 years is often linked to concurrent anthropogenic changes of atmospheric composition and global warming. The idea that a temporal localization of the problem could improve its understanding initiated a search for erratic growth-patterns in earlier periods of high quality dendrochronological archives. An extensive network of maximum latewood density (MXD) measurements from northern Fennoscandia likely represents one of the most reliable regional summer-temperature reconstructions. The strong coherence between proxy and instrumental data is, however, interrupted…
Effects of forest restoration treatments on the abundance of bark beetles in Norway spruce forests of southern Finland
2009
Abstract Restoration of protected areas in boreal forests frequently includes creating substantial volumes of dead wood. While this benefits a wide range of dead wood dependent invertebrate species, some of these are regarded as forest pests. Therefore, the risk of elevated levels of tree mortality in surrounding commercial forests must be considered. In a large-scale field experiment in southern Finland, we studied the effects of restoration treatments on the abundance of bark beetles within and in the vicinity of restored areas, in particular focusing on Ips typographus and Pityogenes chalcographus . The treatments applied to managed Norway spruce forests were controlled burning and parti…
Responses of decomposer community to root-isolation and addition of slash
2001
Abstract We studied the causal relationships between forest harvesting and the soil decomposer community focusing on suppression of energy inputs from trees to the soil through root–mycorrhizal network and increased energy input to the soil in the form of slash left on site. We hypothesised that both of these factors would affect the decomposer community, since the soil food web has been regarded as a system in which the amount of resources controls the numbers of consumers. To study the importance of these factors without changes in microclimate, like in sunshine and shade, taking place in clear-felled areas, the experiment was performed in a mature spruce ( Picea abies (L.) Karst.) forest…
Studies of Components of the Thylakoid Membrane of Undamaged and Damaged Spruce Trees at Different Mountain Sites
1993
During a five-year period, components of the thylakoid membrane in needles of the second generation of undamaged and damaged trees of Norway spruce were studied at three different mountain sites in West Germany. Visible signs of damage at these sites are a yellowing of the light-exposed sides of the needles as well as the loss of needles. The goal of this study was to determine damage-induced alterations in composition and physiological reactions of the thylakoid membranes in spruce needles. In order to meet this purpose, contents of chlorophyll a and b, electron transport rate of photosystem II, contents of the D 1 protein, cytochrome f, as well as P-700 were measured. The chlorophyll cont…