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Sirvi Autor "Lazdina, D." järgi

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  • Pisipilt
    Kirje
    Impact of different fertilisers on elemental content in young hybrid aspen stem wood
    (2020) Bertins, M.; Bardule, A.; Busa, L.; Viksna, A.; Lazdina, D.; Ansone-Bertina, L.
    The biomass production using fast-growing tree species such as hybrid aspen (Populus tremuloides Michx. x Populus tremula L.) has been recognized as an environmentally friendly and cost-effective approach. Growing these species can reduce the negative impact of earlier land mismanagement and at the same time provide additional biomass growth. The application of fertilisers may introduce not only the necessary macro elements (N, P, K) but also significant amounts of toxic heavy metals. Therefore, the knowledge about elemental flows from fertilised soil to the different parts of hybrid aspen trees is essential and especially meaningful for the evaluation of element content in specific environmental ecosystems. The impact of different fertilisers (sewage sludge, digestate and wood ash) on the concentrations of micro- and macro elements in the wood of six-year-old hybrid aspen stands grown on former agricultural land was studied. The determination of element concentrations in different tree rings of hybrid aspen trees was accomplished by inductively coupled plasma mass spectrometry (ICP–MS). Isotope ratio mass spectrometry (IRMS) was used to determine the nitrogen and carbon content and isotope ratios in different parts of hybrid aspen trees. Stem disc samples from hybrid aspen trees were obtained from agricultural land in the central part of Latvia. Samples were taken from six-yearold hybrid aspen trees that at the moment of planting were fertilised with sewage sludge, a residue of biogas production (digestate) and wood ash. The obtained results indicated that the chemical element accumulation in hybrid aspen was affected by the applied fertiliser type. In this study, the use of wood ash, as well as digestate, affected the elemental content in hybrid aspen to a greater extent than the use of sewage sludge, relative to unfertilised (control) subplot. The analysed elements varied in the analysed stem plane (across the tree rings). The most significant changes between the rings were observed for the content of K and Ca.
  • Pisipilt
    Kirje
    Juvenile growth and frost damages of poplar clone OP42 in Latvia
    (2017) Sēnhofa, S.; Neimane, U.; Grava, A.; Sisenis, L.; Lazdina, D.; Jansons, A.
    Short rotation plantations in the northern Europe are commonly established using poplar clone OP42 (Populus maximowiczii Henry × P. trichocarpa Torr. and Gray). We assessed its growth and suitability to the climate in central part of Latvia at juvenile age. Trees that had formed single stem were significantly higher (121 ± 2.5 cm), thicker (7.1 ± 0.48 mm) and had longer branches (32 ± 1.5 cm) than trees that had formed multiple stems. In beginning of the second growing season all trees had died stems and 19.6% of them formed new shoots from the ground level. The sprouting trees had random spatial distribution in the field. Regardless of the number of stems, the sprouting trees were significantly lower (110 ± 3.9 cm) than the dead trees (119 ± 2.0 cm). During the repeated assessment about one month later, proportion of the sprouting trees increased up to 44%, but the detected relations between measured traits of sprouting and dead trees remained. Clone OP42 had serious frost induced damages also in autumn phenology experiment (96% trees with severely damaged leaves). Our results suggest that frost prone sites are not suitable for establishment of plantations of OP42 clone.
  • Pisipilt
    Kirje
    Planting and tending productivity comparison in mounds and disc trenches using containerized and bareroot coniferous seedlings
    (2019) Makovskis, K.; Lazdina, D.; Kaleja, S.; Spalva, G.; Dumins, K.
    In 2016 more then 40,300 ha of forest was regenerated in Latvia, where 13,000 ha were seeded or planted and 30,300 ha were left in natural regeneration. Before planting, usually one of two soil preparation methods are used – mounding or disc trenching. In areas with optimal water regime, disc trenching is used, while in wet areas mounding is used. Tree planting and after planting tending is done manually by hand tools. The aim of the study was to compare planting and tending productivity in different soil preparation methods (mounding and disc trenching) by planting different stocktypes (containerized and bareroot seedlings). Planting time studies were done in 12 sites and tending time studies in 8 sites. In planting time studies, different planting operations were measured and compared. In tending time studies, GPS devices were used, where area, distance and working time (productive and rest) was counted from GPS data. Average planting time for containerized seedlings in disc trenches was 10.3 seconds, while in mounds 9.2 seconds per seedling, an 11% improvement. Average planting time for bareroot seedlings in mounds was 28.3 seconds, while in trenches – 18.2 seconds, a 35% improvement. Tending in trenches was done faster than in mounds. On average, one hectare tending time in mounds was 8.4 hours, while in trenches 7.4 hours, an 11% improvement. Walked distance for 1 hectare tending in mounds was 5.4 km, 7% shorter than the distance of 5.0 km in trenches. Factors that influence planting and tending productivity are soil preparation quality, logging residue, and water level on the site. Data from planting and tending time studies could be used for better plan work activities and select suitable planting material for a particular soil preparation method.