Luke
 

Jukuri

Tervetuloa käyttämään Jukuria, Luonnonvarakeskuksen (Luke) avointa julkaisuarkistoa. Jukurissa on tiedot Luken julkaisutuotannosta. Osa julkaisuista on vapaasti ladattavissa. Luken muodostaneiden tutkimuslaitosten aikaisemmasta julkaisutuotannosta osan tiedot ovat järjestelmässä jo nyt ja kattavuus paranee jatkuvasti.

Viimeksi tallennetut

The diel niche of brown bears: constraints on adaptive capacity in human-modified landscapes
Donatelli, Aurora; Ćirović, Duško; Haroldson, Mark A.; Huber, Đuro; Kindberg, Jonas; Kojola, Ilpo; Kusak, Josip; Mastrantonio, Gianluca; Ordiz, Andrés; Reljić, Slaven; Santini, Luca; van Manen, Frank T.; Ciucci, Paolo
Ecography (Wiley-Blackwell, 2025)
Diel activity rhythms, representing the behavioral pattern of the sleep–wake cycle, may be adjusted by wildlife in response to changes in environmental conditions. An increase in nocturnality is typically recognized as an adaptive strategy to segregate from humans and mitigate heat stress. Numerous studies have investigated spatial patterns and habitat use of large carnivores in human-modified landscapes, but little research has examined their activity rhythms. We compiled Global Positioning System data (2004–2022) for 139 brown bears Ursus arctos from six populations across Europe, representing a human-modified landscape, and the Greater Yellowstone Ecosystem, U.S.A., representing a landscape with limited human impact, which we used to calculate hourly movement rates as an activity proxy. Using a Bayesian approach to model the temporal autocorrelation of activity data, we tested if the extent of nocturnality in brown bears is modulated by intensity of human encroachment, accounting for primary productivity and maximum ambient temperature. All bear populations exhibited a predominantly bimodal, crepuscular pattern of activity, although Yellowstone bears were proportionally more crepuscular and diurnal. Whereas the effect of primary productivity was variable, all European populations became more nocturnal in response to higher human encroachment and reduced diurnal and crepuscular activity at higher summer temperatures, decreasing overall diel activity levels. Yellowstone bears displayed the greatest shift towards nocturnality among all populations in response to increasing human encroachment, and increased nocturnal activity to compensate for lower diurnal and crepuscular activity at higher summer temperatures. Our research indicates that European bears in human-modified landscapes may be reaching a limit in the behavioral plasticity they can manifest in their activity patterns, being already constrained into increased nocturnality. Our findings enhance the understanding of brown bear adaptive capacity to accommodate future changes, such as urbanization and increasing temperatures, to the ecosystems they inhabit.
Effects of propagation method and methyl jasmonate treatment on stem bark wound healing in Norway spruce seedlings
Berggren, Kristina; Tudoran, Amelia; Chen, Yayuan; Tikkinen, Mikko; Bylund, Helena; Björkman, Christer; Egertsdotter, Ulrika; Puentes, Adriana
European journal of forest research (Springer Nature, 2025)
Healing of stem bark wounds is important for minimizing pathogen infection risk, restoring nutrient transport and structural support in trees. Here, we explore how propagation through somatic embryogenesis (SE) and methyl jasmonate (MeJA) treatment affect wound healing ability in Norway spruce (Picea abies) plants. We inflicted a mechanical wound on the lower stem of MeJA- and non-treated plants produced via SE (emblings) or from seeds (seedlings). Visible signs of healing around the wound edges (onset of healing) were recorded 2 weeks post-wounding; wound size (exposed xylem) was measured every other week (June–September) in year 1, and May and September in year 2. Plant height and diameter were also measured. MeJA positively affected healing onset, with 48% more MeJA- than non-treated plants exhibiting early healing. This resulted in a sharp decrease in wound size for MeJA-treated plants 2–4 weeks post-wounding. However, these benefits only occurred early on, as MeJA reduced the overall healing rate (tissue growth/day) by 9%. For SE, fewer emblings (70%) showed early healing signs compared to seedlings (91%). Yet, non-treated emblings showed the highest healing rate during year 1; in year 2, these effects persisted with all emblings having a 61% faster healing rate and 68% more had completely closed their wounds relative to seedlings. Wounding did not affect growth, MeJA negatively affected diameter but not height, and overall emblings grew less than seedlings. We conclude that MeJA may stimulate stem wound healing initiation in Norway spruce, but slow down healing rate and vice versa for SE plants.
Evaluating sawdust-based bioethanol and pyrolysis products in the European Union: Feedstock availability, life cycle assessment, and techno-economic analysis
Ghani, Hafiz Usman; Ilvesniemi, Hannu; Leinonen, Ilkka; Ruuttunen, Kyösti; Khan, Md Musharof Hussain; Oinas, Pekka; Anttila, Perttu
Environmental Impact Assessment Review (Elsevier, 2025)
The significance of biomass-derived biofuels in global transport is increasing due to their perceived environmental advantages and policies with binding use targets. This study conducted a comprehensive sustainability analysis of sawdust-based bioethanol in the European Union, encompassing evaluations of sawdust availability, techno-economic assessment (TEA), and global warming potential (GWP), including land use and land-use-change-related GWP (GWP-LULUC). It was found that bioethanol production based on average annual sawdust potential could replace only 0.5 % of total fuel consumption in the EU transport sector in 2021, provided that all the sawdust was used for this purpose. The TEA calculations indicated that, while technically feasible, the economics of sawdust-based bioethanol production are not favourable based on this research's assumptions. Pyrolysis-based bioproducts showed better profitability. The economics of bioethanol production depends greatly on the sawdust cost, which was shown by the sensitivity analysis conducted. The GWP results highlighted the potential environmental benefits of ethanol-blended fuels such as E20 (20 % bioethanol with gasoline) and E85 (85 % bioethanol with gasoline), demonstrating reductions of 18 % and 78 % in fossil GWP impacts compared to petrol respectively. Examining GWP-LULUC unveiled a notable sequestration effect, primarily due to increased carbon storage in forests. However, these effects vary depending on the production year, country of origin, or soil type. In the context of this study, sawdust-based bioethanol demonstrated the potential to replace some fossil fuels, offering technical feasibility and considerable environmental benefits. However, it is not economically feasible and is highly influenced by policy changes and competition among different sectors.
WetCH4: a machine-learning-based upscaling of methane fluxes of northern wetlands during 2016–2022
Ying, Qing; Poulter, Benjamin; Watts, Jennifer D; Arndt, Kyle A; Virkkala, Anna-Maria; Bruhwiler, Lori; Oh, Youmi; Rogers, Brendan M; Natali, Susan M; Sullivan, Hilary; Armstrong, Amanda; Ward, Eric J; Schiferl, Luke D; Elder, Clayton D; Peltola, Olli; Bartsch, Annett; Desai, Ankur R; Euskirchen, Eugenie; Goeckede, Mathias; Lehner, Bernhard; Nilsson, Mats B; Peichl, Matthias; Sonnentag, Oliver; Tuittila, Eeva-Stiina; Sachs, Torsten; Kalhori, Aram; Ueyama, Masahito; Zhang, Zhen
Earth system science data : 6 (Copernicus publications, 2025)
Wetlands are the largest natural source of methane (CH4) emissions globally. Northern wetlands (>45° N), accounting for 42 % of global wetland area, are increasingly vulnerable to carbon loss, especially as CH4 emissions may accelerate under intensified high-latitude warming. However, the magnitude and spatial patterns of high-latitude CH4 emissions remain relatively uncertain. Here, we present estimates of daily CH4 fluxes obtained using a new machine learning-based wetland CH4 upscaling framework (WetCH4) that combines the most complete database of eddy-covariance (EC) observations available to date with satellite remote-sensing-informed observations of environmental conditions at 10 km resolution. The most important predictor variables included near-surface soil temperatures (top 40 cm), vegetation spectral reflectance, and soil moisture. Our results, modeled from 138 site years across 26 sites, had relatively strong predictive skill, with a mean R2 of 0.51 and 0.70 and a mean absolute error (MAE) of 30 and 27 nmol m−2 s−1 for daily and monthly fluxes, respectively. Based on the model results, we estimated an annual average of 22.8±2.4 Tg CH4 yr−1 for the northern wetland region (2016–2022), and total budgets ranged from 15.7 to 51.6 Tg CH4 yr−1, depending on wetland map extents. Although 88 % of the estimated CH4 budget occurred during the May–October period, a considerable amount (2.6±0.3 Tg CH4) occurred during winter. Regionally, the Western Siberian wetlands accounted for a majority (51 %) of the interannual variation in domain CH4 emissions. Overall, our results provide valuable new high-spatiotemporal-resolution information on the wetland emissions in the high-latitude carbon cycle. However, many key uncertainties remain, including those driven by wetland extent maps and soil moisture products and the incomplete spatial and temporal representativeness in the existing CH4 flux database; e.g., only 23 % of the sites operate outside of summer months, and flux towers do not exist or are greatly limited in many wetland regions. These uncertainties will need to be addressed by the science community to remove the bottlenecks currently limiting progress in CH4 detection and monitoring. The dataset can be found at https://doi.org/10.5281/zenodo.10802153 (Ying et al., 2024).
L-moments Reveal the Scales of Momentum Transport in Dense Canopy Flows
Chowdhuri, Subharthi; Peltola, Olli
Boundary-layer meteorology : 3 (Springer Nature, 2025)
The interaction between a dense forest canopy and atmosphere is a complex fluid-dynamical problem with a wide range of practical applications, spanning from the aspects of carbon sequestration to the spread of wildfires through a forest. To delineate the eddy processes specific to canopy flows, we develop an L-moment based event framework and apply it on a suite of observational datasets encompassing both canopy and atmospheric surface layer flows. In this framework, the turbulent fluctuations are considered as a chronicle of positive and negative events having finite lengths or time scales, whose statistical distributions are quantified through the L moments. L moments are statistically more robust than the conventional moments and have earlier been used in hydrology applications, but here we show how this concept is useful to identify the contrasting features between canopy and atmospheric surface layer flows. The L-moment framework is complemented with wavelet analysis, revealing how differently the canopy-scale coherent structures modulate the horizontal and vertical velocity components in sub-canopy environments. We hypothesize that a consequence of this phenomenon is the existence of two different eddy processes with distinct scaling properties that transport momentum in the gradient and counter-gradient directions, respectively. These findings shed light on a long-standing issue in canopy flows: why the integral timescale of vertical velocity increases as the heights approach the forest floor?