EMU DSpace – Eesti Maaülikooli digitaalarhiiv
Digitaalarhiiv EMU DSpace kogub, säilitab ja loob ligipääsu Eesti Maaülikooli liikmeskonna poolt loodud või Eesti Maaülikooli vastutusvaldkondadega seotud teadustöödele toetamaks maaülikooli konkurentsivõimet ja teadmistepõhist ühiskonna arengut. Digitaalarhiivi haldab Eesti Maaülikooli raamatukogu.
Valdkonnad DSpace's
Valige valdkond, et selle kogusid sirvida.
- Institute of Forestry and Engineering (MMI)
- Institute of Agricultural and Environmental Sciences (PKI)
- Institute of Veterinary Medicine and Animal Sciences (VLI)
- Publications
- Units
Hiljutised sisestused
Response on light interception and radiation use efficiency of selected winter cereals at optimum N fertilizers : [Retracted]
(Estonian University of Life Sciences, 2018) Biabani, A.; Etesam, M.; Rahemi Karizaki, A.; Gholizadeh, A.; Sabouri, H.
Audoktor Marian Kazda
(Eesti Maaülikool, 2024) Eesti Maaülikool
Ulmi Ülikooli emeriitprofessor Marian Kazda nimetati Eesti Maaülikooli audoktoriks 23. mail 2024.
The effect of different harvesting methods on carbon cycling and productivity of forest ecosystems
(Estonian University of Life Sciences, 2024) Uri, Marek; Uri, Veiko (advisor); Varik, Mats (advisor); Institute of Forestry and Engineering; Palviainen, Marjo (opponent)
The forests of the northern hemisphere are the important natural carbon (C) sinks in terrestrial ecosystems, however, the C sequestration capacity of stands can be significantly affected by different harvesting methods. Clear-cutting is the prevailing forest management method in Northern Europe, and its effect on the C cycle of the site is appreciable. Clear-cuts act as C sources and quantification of the amount of C loss, as well as evaluation of the post harvesting recovery dynamics of C balance are crucial issues. The annual net ecosystem production (NEP) of mesotrophic pine and fertile silver birch clear-cut areas varied between 1.7-1.9 and 0.4-0.5 t C ha-1 yr-1, respectively. The ecosystem turned into a C sink at a stand age of seven years for Scots pine and six years for silver birch. The C payback period, which indicates the time lag for replenishing the cumulative C loss before C balancing, was estimated at age of 12 and 10 years for Scots pine and silver birch, respectively.
Shelterwood cutting (SWC) allows avoidance of drastic changes in the landscape and is recognized as an alternative method to clear-cutting. However, the impact of SWC on C stocks and C fluxes of the forest ecosystem is still a relatively poorly studied issue. In the current study, one of the studied stands turned into a C source after SWC, while the other remained a weak C sink (-1.3 and 0.6 t C ha-1 yr-1, respectively). Although in the short term, SWC demonstrated a certain advantage over clear-cut in terms of the C cycle, then for relevant evaluation, the whole rotation cycle should be considered. The net ecosystem exchange for the post-SWC area, measured by the eddy covariance technique in the first post-harvesting year, showed a larger C sink than that estimated by the budgeting method. The above divergence was largely induced by the cumulative uncertainty of NEP, which is inherent in the bottom-up budgeting approach.
In Estonia, the more extensive implementation of selective cuttings and the principles of continuous cover forest management in forestry are increasingly highlighted. Based on the results of experimental transitional selective cuttings in mature mesotrophic pine stands it would be possible to maintain the old stand over a longer period in case a considerable amount of timber is removed by repeated cuttings. The results of the simulated further growth dynamics of post-harvested stands showed a considerably lower total wood production over the following 40 years compared to the production of forests formed after clear-cut.
Proteome profile of bovine uterine extracellular vesicles during the oestrous cycle and in endometritis
(Estonian University of Life Sciences, 2024) Piibor, Johanna; Valdmann, Andres (advisor); Institute of Veterinary Medicine and Animal Sciences; Forde, Niamh (opponent)
Uterine fluid (UF) provides a microenvironment for the growth and survival of pre-implantation embryos and facilitates embryo-maternal communication. While effective communication and nurturing of pre-implantation embryos via UF contribute to improved embryonic implantation and development, the disrupted or suboptimal conditions can lead to implantation failure and pregnancy loss. Recent studies have revealed the role of extracellular vesicles (EVs) in cell-to-cell communication. EVs are lipid membrane-bound nanoparticles containing a range of biomolecules, which when transferred from one cell to another can influence the state of another cell. Several postpartum reproductive inflammatory diseases have been documented, with endometritis emerging as the primary long-lasting fertility-affecting ailment. Postpartum endometritis in dairy cattle refers to inflammation of the endometrium that occurs three weeks or more after parturition, exhibiting no systemic signs of illness. We studied the bovine UF-EV profiles in healthy cows and those with endometritis. We found that UF-EV concentration, size and proteomic profile show clear differences between follicular and luteal phases in naturally cyclic, the days of the oestrous cycle in synchronized cows and cows with clinical (CLE) and subclinical endometritis (SE). Moreover, supplementing UF-EVs from cows with CLE or SE to embryo cultures in vitro had determinantal impact on blastocyst rates and/or quality compared to UF-EVs from healthy cows. Our study identified HTRA1 as potential biomarker for SE. Future investigations building upon the insights gained from this thesis could potentially address challenges with diagnosing SE and improve in vitro fertilization technologies (e.g., increase blastocyst rates, improve embryo quality) making it more feasible to use in farms.
Delayed storm and salvage logging effects on forest vegetation recovery and development
(Estonian University of Life Sciences, 2024) Palm-Hellenurm, Kristiina; Vodde, Floortje (advisor); Jõgiste, Kalev (advisor); Tullus, Tea (advisor); Institute of Forestry and Engineering; Hedwall, Per-Ola (opponent)
The doctoral thesis examined the diversity and composition of understory communities in permanent sample plots established in hemiboreal spruce-hardwood forests, where storm disturbance occurred approximately 20 years ago. Data were also collected from control areas in forests of a similar type that were unaffected by wind disturbance, as well as from post-storm salvage-logged sample plots. In addition, the main agents and processes influencing the fate of remnant trees (i.e., trees that survived a wind disturbance) were analyzed to provide insights into the temporal stability of these important biological legacies.
Light conditions, microsite richness and substrate diversity differed significantly among treatments, whereas salvaged areas exhibited the greatest canopy openness and the lowest levels of microsite richness and substrate diversity. Altogether, 100 herb and dwarf shrub taxa and 108 bryophyte taxa (81 mosses and 27 liverworts) were found in the study plots. Vascular plant and bryophyte communities exhibited contrasting responses due to their differing habitat requirements, life-history strategies, and the resource competition between these two groups. Salvaged stands displayed higher coverage and species richness of herbaceous species compared to uncleared wind-disturbed areas and control plots. Salvaging did not have a detrimental effect on bryophyte species richness compared to reference sites (control plots), but wind-damaged, unharvested areas hosted significantly more diverse bryophyte communities than both control and salvaged plots.
The understory assemblages in salvaged plots differed most from those in reference plots, indicating significant changes in species composition and community structure following salvage logging. Moderately damaged study plots displayed the highest variability in terms of species composition compared to other treatments, highlighting the importance of these areas in maintaining beta-diversity at the landscape scale. Temporal stability of wind-disturbed ecosystems can, however, be compromised due to the high susceptibility of the remnant trees to further disturbances.
Many species, including several of high conservation value, were found only in unsalvaged storm-affected areas, confirming the positive impact of wind disturbance on biodiversity. At the same time, salvage logging may help prevent future disturbances that could exceed the ecosystem’s resilience threshold, while also reducing timber loss and carbon emissions. Therefore, the selection and implementation of post-disturbance management methods and practices require a comprehensive analysis.
The results demonstrated that plant species groups with distinctive life-history traits exhibit different mid-succession responses to wind disturbances and post-windthrow salvaging. Disturbance legacies such as surviving remnant trees, snags, coarse woody debris, and pit-and-mound complexes can promote habitat heterogeneity, enhance biodiversity, and support ecological resilience in post-disturbance forest ecosystems. Thus, it is advisable to retain some biological legacies of wind disturbances – such as pit-and-mound complexes, snags, woody debris, and remnant trees – during salvage operations, as these elements are crucial for maintaining structural diversity and providing essential habitats for various plant species.