Browsing by Subject "PRODUCTIVITY"

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  • Laanto, Elina; Mäkelä, Kati; Hoikkala, Ville; Ravantti, Janne; Sundberg, Lotta-Riina (2020)
    Phage therapy is becoming a widely recognized alternative for fighting pathogenic bacteria due to increasing antibiotic resistance problems. However, one of the common concerns related to the use of phages is the evolution of bacterial resistance against the phages, putatively disabling the treatment. Experimental adaptation of the phage (phage training) to infect a resistant host has been used to combat this problem. Yet, there is very little information on the trade-offs of phage infectivity and host range. Here we co-cultured a myophage FCV-1 with its host, the fish pathogenFlavobacterium columnare, in lake water and monitored the interaction for a one-month period. Phage resistance was detected within one day of co-culture in the majority of the bacterial isolates (16 out of the 18 co-evolved clones). The primary phage resistance mechanism suggests defense via surface modifications, as the phage numbers rose in the first two days of the experiment and remained stable thereafter. However, one bacterial isolate had acquired a spacer in its CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat)-Cas locus, indicating that also CRISPR-Cas defense was employed in the phage-host interactions. After a week of co-culture, a phage isolate was obtained that was able to infect 18 out of the 32 otherwise resistant clones isolated during the experiment. Phage genome sequencing revealed several mutations in two open reading frames (ORFs) likely to be involved in the regained infectivity of the evolved phage. Their location in the genome suggests that they encode tail genes. Characterization of this evolved phage, however, showed a direct cost for the ability to infect several otherwise resistant clones-adsorption was significantly lower than in the ancestral phage. This work describes a method for adapting the phage to overcome phage resistance in a fish pathogenic system.
  • Hu, Man; Lehtonen, Aleksi; Minunno, Francesco; Mäkelä, Annikki (2020)
    Tree structure equations derived from pipe model theory (PMT) are well-suited to estimate biomass allocation in Scots pine (Pinus sylvestrisL.) and Norway spruce (Picea abies[L.] Karst.). However, age dependence of parameters should be accounted for when applying the equations.
  • Villa, Ana; Eckersten, H.; Gaiser, Thomas; Ahrends, Hella Ellen; Lewan, E. (2022)
    Predicting areas of severe biomass loss and increased N leaching risk under climate change is critical for applying appropriate adaptation measures to support more sustainable agricultural systems. The frequency of annual severe biomass loss for winter wheat and its coincidence with an increase in N leaching in a temperate region in Germany was estimated including the error from using soil and climate input data at coarser spatial scales, using the soil-crop model CoupModel. We ran the model for a reference period (1980–2010) and used climate data predicted by four climate model(s) for the Representative Concentration Pathways (RCP) 2.6, 4.5 and 8.5. The annual median biomass estimations showed that for the period 2070–2100, under the RCP8.5 scenario, the entire region would suffer from severe biomass loss almost every year. Annual incidence of severe biomass loss and increased N leaching was predicted to increase from RCP4.5 to the 8.5 scenario. During 2070–2100 for RCP8.5, in more than half of the years an area of 95% of the region was projected to suffer from both severe biomass loss and increased N leaching. The SPEI3 predicted a range of 32 (P3 RCP4.5) to 55% (P3 RCP8.5) of the severe biomass loss episodes simulated in the climate change scenarios. The simulations predicted more severe biomass losses than by the SPEI index which indicates that soil water deficits are important in determining crop losses in future climate scenarios. There was a risk of overestimating the area where “no severe biomass loss + increased N leaching” occurred when using coarser aggregated input data. In contrast, underestimation of situations where “severe biomass loss + increased N leaching” occurred when using coarser aggregated input data. Larger annual differences in biomass estimations compared to the finest resolution of input data occurred when aggregating climate input data rather than soil data. The differences were even larger when aggregating both soil and climate input data. In half of the region, biomass could be erroneously estimated in a single year by more than 40% if using soil and climate coarser input data. The results suggest that a higher spatial resolution of especially climate input data would be needed to predict reliably annual estimates of severe biomass loss and N leaching under climate change scenarios.
  • Vuorinne, Ilja; Heiskanen, Janne; Maghenda, Marianne; Mwangala, Lucas; Muukkonen, Petteri; Pellikka, Petri K.E. (2021)
    Biomass is a key variable for crop monitoring and for assessing carbon stocks and bioenergy potential. This study aimed to develop an allometric model for predicting the dry leaf biomass of sisal, an agave plant with crassulacean acid metabolism grown for fibre production in the tropics and subtropics and whose biomass can be utilised as a feedstock to produce biogas through anaerobic digestion. The allometric model was used to estimate leaf biomass and productivity across different stand ages in a sisal plantation in semi-arid region in south-east Kenya (annual rainfall 611 mm and temperature 24.9 °C). Based on a sample of 38 leaves, the best predictor for biomass was leaf maximum width and plant height used as a combined variable in a log-log regression model (cross-validated R2 = 0.96 and root-mean-square error = 7.69 g). The mean productivity in nine 26- to 36-month-old plots was 11.1 Mg ha−1 yr−1, which could potentially yield approximately 3000 m3 CH4 ha−1 yr−1. The leaf biomass in 55 field plots (400 m2 in area) ranged from 2.7 to 42.7 Mg ha−1, with mean at 13.5 Mg ha−1, which equals to 6.3 Mg C ha−1. The yielded allometric equations can be utilised for predicting the leaf biomass of sisal in similar agro-ecological zones. The estimates on plantation biomass can be used in assessing the role of sisal plantations as a regional carbon storage. In addition, the results provide reference on the productivity of agave and crassulacean acid metabolism in semi-arid regions of East Africa, where such reports are few.
  • Gedefaw, Melakeneh G.; Geli, Hatim M. E.; Abera, Temesgen (2021)
    Rangelands provide significant socioeconomic and environmental benefits to humans. However, climate variability and anthropogenic drivers can negatively impact rangeland productivity. The main goal of this study was to investigate structural and productivity changes in rangeland ecosystems in New Mexico (NM), in the southwestern United States of America during the 1984-2015 period. This goal was achieved by applying the time series segmented residual trend analysis (TSS-RESTREND) method, using datasets of the normalized difference vegetation index (NDVI) from the Global Inventory Modeling and Mapping Studies and precipitation from Parameter elevation Regressions on Independent Slopes Model (PRISM), and developing an assessment framework. The results indicated that about 17.6% and 12.8% of NM experienced a decrease and an increase in productivity, respectively. More than half of the state (55.6%) had insignificant change productivity, 10.8% was classified as indeterminant, and 3.2% was considered as agriculture. A decrease in productivity was observed in 2.2%, 4.5%, and 1.7% of NM's grassland, shrubland, and ever green forest land cover classes, respectively. Significant decrease in productivity was observed in the northeastern and southeastern quadrants of NM while significant increase was observed in northwestern, southwestern, and a small portion of the southeastern quadrants. The timing of detected breakpoints coincided with some of NM's drought events as indicated by the self-calibrated Palmar Drought Severity Index as their number increased since 2000s following a similar increase in drought severity. Some breakpoints were concurrent with some fire events. The combination of these two types of disturbances can partly explain the emergence of breakpoints with degradation in productivity. Using the breakpoint assessment framework developed in this study, the observed degradation based on the TSS-RESTREND showed only 55% agreement with the Rangeland Productivity Monitoring Service (RPMS) data. There was an agreement between the TSS-RESTREND and RPMS on the occurrence of significant degradation in productivity over the grasslands and shrublands within the Arizona/NM Tablelands and in the Chihuahua Desert ecoregions, respectively. This assessment of NM's vegetation productivity is critical to support the decision-making process for rangeland management; address challenges related to the sustainability of forage supply and livestock production; conserve the biodiversity of rangelands ecosystems; and increase their resilience. Future analysis should consider the effects of rising temperatures and drought on rangeland degradation and productivity.
  • Camarena-Gomez, Maria Teresa; Ruiz-Gonzalez, Clara; Piiparinen, Jonna; Lipsewers, Tobias; Sobrino, Cristina; Logares, Ramiro; Spilling, Kristian (2021)
    In parts of the Baltic Sea, the phytoplankton spring bloom communities, commonly dominated by diatoms, are shifting toward the co-occurrence of diatoms and dinoflagellates. Although phytoplankton are known to shape the composition and function of associated bacterioplankton communities, the potential bacterial responses to such a decrease of diatoms are unknown. Here we explored the changes in bacterial communities and heterotrophic production during the spring bloom in four consecutive spring blooms across several sub-basins of the Baltic Sea and related them to changes in environmental variables and in phytoplankton community structure. The taxonomic structure of bacterioplankton assemblages was partially explained by salinity and temperature but also linked to the phytoplankton community. Higher carbon biomass of the diatomsAchnanthes taeniata,Skeletonema marinoi,Thalassiosira levanderi, andChaetocerosspp. was associated with more diverse bacterial communities dominated by copiotrophic bacteria (Flavobacteriia, Gammaproteobacteria, and Betaproteobacteria) and higher bacterial production. During dinoflagellate dominance, bacterial production was low and bacterial communities were dominated by Alphaproteobacteria, mainly SAR11. Our results suggest that increases in dinoflagellate abundance during the spring bloom will largely affect the structuring and functioning of the associated bacterial communities. This could decrease pelagic remineralization of organic matter and possibly affect the bacterial grazers communities.
  • Passy, Sophia I.; Larson, Chad A.; Jamoneau, Aurelien; Budnick, William; Heino, Jani; Leboucher, Thibault; Tison-Rosebery, Juliette; Soininen, Janne (2018)
    In this intercontinental study of stream diatoms, we asked three important but still unresolved ecological questions: (1) What factors drive the biogeography of species richness and species abundance distribution (SAD)? (2) Are climate-related hypotheses, which have dominated the research on the latitudinal and altitudinal diversity gradients, adequate in explaining spatial biotic variability? and (3) Is the SAD response to the environment independent of richness? We tested a number of climatic theories and hypotheses (i.e., the species-energy theory, the metabolic theory, the energy variability hypothesis, and the climatic tolerance hypothesis) but found no support for any of these concepts, as the relationships of richness with explanatory variables were nonexistent, weak, or unexpected. Instead, we demonstrated that diatom richness and SAD evenness generally increased with temperature seasonality and at mid- to high total phosphorus concentrations. The spatial patterns of diatom richness and the SADmainly longitudinal in the United States but latitudinal in Finlandwere defined primarily by the covariance of climate and water chemistry with space. The SAD was not entirely controlled by richness, emphasizing its utility for ecological research. Thus, we found support for the operation of both climate and water chemistry mechanisms in structuring diatom communities, which underscores their complex response to the environment and the necessity for novel predictive frameworks.
  • Waldén, Pirjetta; Ollikainen, Markku; Kahiluoto, Helena (2020)
    The impact of carbon revenue on the profitability of agroforestry systems in comparison to monocultures is unexplored in regard to Sub-Saharan Africa. This study creates a multivariate model to evaluate the impact of carbon revenue on the profitability of agroforestry relative to the dominant monocultures in Ethiopia by using stylized plots. Yields and carbon stock changes of eight agroforestry systems were modeled based on data from agroforestry plots in the Ethiopian Central Rift Valley. According to our model, agroforestry was, on average, four times more profitable than the main monoculture systems (wheat, barley, maize, teff, sorghum, sugarcane and lentil) even when carbon revenues were excluded, primarily due to the higher prices of fruit produce. Carbon revenues were estimated using a plausible carbon price ranging from US$8/tCO2e to $40/tCO2e and carbon sequestration rates of 0.59 to 17.2 Mg C ha−1 year−1. The possibility of receiving carbon revenue increased the profitability of agroforestry by 0.5% when using the lowest utilized carbon price and carbon sequestration rate, by 20% when using the carbon price of $20 and the average carbon sequestration rate, and by 70% when using the highest price and highest sequestration rate of carbon. On average, carbon revenue increased the profitability of agroforestry by 150% in comparison to monoculture farming. We conclude that carbon income may have significant potential to motivate smallholders to convert to agroforestry when there is a proper management system, a sufficiently high carbon price and effective institutional support to mitigate the transition and transaction costs.
  • Tommila, Tero; Kämäräinen, Antti; Kokko, Harri; Palonen, Pauliina (2022)
    Methods for protected container cultivation of arctic bramble (Rubus arcticus L.) are currently under development. The aim of this study was to evaluate coir and wood shavings as alternatives to peat-based growth substrate (growing medium) in the intensive greenhouse cultivation of arctic bramble. The substrates used were a commercial coir mix (Coir), wood shavings from sodium silicate impregnated wood (Wood), a mixture of 95 % horticultural peat and 5 % perlite (HPP), and a mixture of 80 % peat and 20 % wood shavings (HPWood). Growth and fruit yield were highest in HPP, followed by Coir and HPWood, and were most severely reduced in Wood. Shoot nutrient analyses and soil drainage water observations suggested that the poor performance of Wood was mainly caused by release of sodium silicate into the rooting zone due to unsuccessful substrate processing. A higher proportion of the pore space in Wood was air-filled compared to other substrates, possibly limiting water availability. Overall, the suitability of both coir and wood shavings as growth substrates for arctic bramble was relatively low. However, it is likely that the poor performance of wood shavings was caused largely by inappropriate preparation. For wood waste to be useful as a growth substrate, the wood material should be specially processed for that purpose.
  • Xue, Hailian; Mäkelä, Aino Annikki; Valsta, Lauri Tapani; Vanclay, Jerome; Cao, Tianjian (2019)
    Stand management optimization has long been computationally demanding as increasingly detailed growth and yield models have been developed. Process-based growth models are useful tools for predicting forest dynamics. However, the difficulty of classic optimization algorithms limited its applications in forest planning. This study assessed alternative approaches to optimizing thinning regimes and rotation length using a process-based growth model. We considered (1) population-based algorithms proposed for stand management optimization, including differential evolution (DE), particle swarm optimization (PSO), evolution strategy (ES), and (2) derivative-free search algorithms, including the Nelder–Mead method (NM) and Osyczka’s direct and random search algorithm (DRS). We incorporated population-based algorithms into the simulation-optimization system OptiFor in which the process-based model PipeQual was the simulator. The results showed that DE was the most reliable algorithm among those tested. Meanwhile, DRS was also an effective algorithm for sparse stands with fewer decision variables. PSO resulted in some higher objective function values, however, the computational time of PSO was the longest. In general, of the population-based algorithms, DE is superior to the competing ones. The effectiveness of DE for stand management optimization is promising and manifested.
  • Li, Zhouyuan; Zhang, Heng; Xu, Yanjie; Wang, Shaopeng (2021)
    1. Rapid biodiversity loss has triggered decades of research on the relationships between biodiversity and community stability. Recent studies highlighted the importance of species traits for understanding biodiversity-stability relationships. The species with high growth rates ('fast' species) are expected to be less resistant to environmental stress but recover faster if disturbed; in contrast, the species with slow growth rates ('slow' species) can be more resistant but recover more slowly if disturbed. Such a 'fast-slow' trait continuum provides a new perspective for understanding community stability, but its validity has mainly been examined in plant communities. Here, we investigate how 'fast-slow' trait composition, together with species richness and environmental factors, regulate avian community stability at a continental scale. 2. We used bird population records from the North American Breeding Bird Survey during 1988-2017 and defined avian community stability as the temporal invariability of total community biomass. We calculated species richness and the community-weighted mean (CWM) and functional diversity (FD) of four key life-history traits, including body size, nestling period (i.e. period of egg incubation and young bird fledging), life span and clutch size (i.e. annual total number of eggs). Environmental factors included temperature, precipitation and leaf area index (LAI). 3. Our analyses showed that avian community stability was mainly driven by the CWM of the 'fast-slow' trait. Communities dominated by 'fast' species (i.e. species with small body size, short nestling period and life span and large clutch size) were more stable than those dominated by 'slow' species (i.e. species with large body size, long nestling period and life span and small clutch size). Species richness and the FD of the 'fast-slow' trait explained much smaller proportions of variation in avian community stability. Temperature had direct positive effects on avian community stability, while precipitation and leaf area index affected community stability indirectly by influencing species richness and trait composition. 4. Our study demonstrates that composition of 'fast-slow' traits is the major biotic driver of avian community stability over North America. Temperature is the most important abiotic factor, but its effect is weaker than that of the 'fast-slow' trait. An integrated framework combining 'fast-slow' trait composition and temperature is needed to understand the response of avian communities in a changing environment.
  • Galbrun, Esther; Tang, Hui; Fortelius, Mikael; Zliobaite, Indre (2018)
    As organisms are adapted to their environments, assemblages of taxa can be used to describe environments in the present and in the past. Here, we use a data mining method, namely redescription mining, to discover and analyze patterns of association between large herbivorous mammals and their environments via their functional traits. We focus on functional properties of animal teeth, characterized using a recently developed dental trait scoring scheme. The teeth of herbivorous mammals serve as an interface to obtain energy from food, and are therefore expected to match the types of plant food available in their environment. Hence, dental traits are expected to carry a signal of environmental conditions. We analyze a global compilation of occurrences of large herbivorous mammals and of bioclimatic conditions. We identify common patterns of association between dental traits distributions and bioclimatic conditions and discuss their implications. Each pattern can be considered as a computational biome. Our analysis distinguishes three global zones, which we refer to as the boreal-temperate moist zone, the tropical moist zone and the tropical-subtropical dry zone. The boreal-temperate moist zone is mainly characterized by seasonal cold temperatures, a lack of hypsodonty and a high share of species with obtuse lophs. The tropical moist zone is mainly characterized by high temperatures, high isothermality, abundant precipitation and a high share of species with acute rather than obtuse lophs. Finally, the tropical dry zone is mainly characterized by a high seasonality of temperatures and precipitation, as well as high hypsodonty and horizodonty. We find that the dental traits signature of African rain forests is quite different from the signature of climatically similar sites in North America and Asia, where hypsodont species and species with obtuse lophs are mostly absent. In terms of climate and dental signatures, the African seasonal tropics share many similarities with Central-South Asian sites. Interestingly, the Tibetan plateau is covered both by redescriptions from the tropical-subtropical dry group and by redescriptions from the boreal-temperate moist group, suggesting a combination of features from both zones in its dental traits and climate.
  • Gora, Evan M.; Kneale, Riley C.; Larjavaara, Markku; Muller-Landau, Helene C. (2019)
    Woody debris (WD) stocks and fluxes are important components of forest carbon budgets and yet remain understudied, particularly in tropical forests. Here we present the most comprehensive assessment of WD stocks and fluxes yet conducted in a tropical forest, including one of the first tropical estimates of suspended WD. We rely on data collected over 8 years in an old-growth moist tropical forest in Panama to quantify spatiotemporal variability and estimate minimum sample sizes for different components. Downed WD constituted the majority of total WD mass (78%), standing WD contributed a substantial minority (21%), and suspended WD was the smallest component (1%). However, when considering sections of downed WD that are elevated above the soil, the majority of WD inputs and approximately 50% of WD stocks were disconnected from the forest floor. Branchfall and liana wood accounted for 17 and 2% of downed WD, respectively. Residence times averaged 1.9 years for standing coarse WD (CWD; > 20 cm diameter) and 3.6 years for downed CWD. WD stocks and inputs were highly spatially variable, such that the sampling efforts necessary to estimate true values within 10% with 95% confidence were > 130 km of transects for downed CWD and > 550 ha area for standing CWD. The vast majority of studies involve much lower sampling efforts, suggesting that considerably more data are required to precisely quantify tropical forest WD pools and fluxes. The demonstrated importance of elevated WD in our study indicates a need to understand how elevation above the ground alters decomposition rates and incorporate this understanding into models of forest carbon cycling.
  • Saksa, Timo; Uusitalo, Jori; Lindeman, Harri; Häyrynen, Esko; Kulju, Sampo; Huuskonen, Saija (2021)
    Precision forestry-i.e., the division of a stand to smaller units and managing of the stand at a micro-stand level-provides new possibilities to increase forest growth, arrange forest stand structure and enhance forest health. In the regeneration phase by adjusting the tree species selection, soil preparation, intensity of regeneration measures (method, planting density, and material), and young stand management procedures according to precise information on soil properties (e.g., site fertility, wetness, and soil type) and microtopography will inevitably lead to an increase in growth of the whole stand. A new approach to utilizing harvester data to delineate micro-stands inside a large forest stand and to deciding the tree species to plant for each micro-stand was piloted in central Finland. The case stands were situated on Finsilva Oyj forest property. The calculation of the local growth (m(3)/ha/year) for each 16 x 16-m grid cell was based on the height of the dominant trees and the stand age of the previous tree generation. Tree heights and geoinformation were collected during cutting operation as the harvester data, and the dominant height was calculated as the mean of the three largest stems in each grid cell. The stand age was obtained from the forest management plan. The estimated local growth (average of nine neighboring grid cells) varied from 3 to 14 m(3)/ha/year in the case stands. When creating micro-stands, neighboring grid cells with approximately the same local growth were merged. The minimum size for an acceptable micro-stand was set to 0.23 ha. In this case study, tree species selection (Scots pine or Norway spruce) was based on the mean growth of each micro-stand. Different threshold values, varying from 6 to 8 m(3)/ha/year, were tested for tree species change, and they led to different solutions in the delineation of micro-stands. Further stand development was simulated with the Motti software and the net present values (NPVs (3%)) for the next rotation were estimated for different micro-stand solutions. The mixed Norway spruce-Scots pine stand structure never produced a clearly economically inferior solution compared to the single species stand, and in one case out of six, it provided a distinctly better solution in terms of NPV (3%) than the single species option did. Our case study showed that this kind of method could be used as a decision support tool at the regeneration phase.
  • Schartau, Ann Kristin; Mariash, Heather L.; Christoffersen, Kirsten S.; Bogan, Daniel; Dubovskaya, Olga P.; Fefilova, Elena B.; Hayden, Brian; Ingvason, Haraldur R.; Ivanova, Elena A.; Kononova, Olga N.; Kravchuk, Elena S.; Lento, Jennifer; Majaneva, Markus; Novichkova, Anna A.; Rautio, Milla; Ruhland, Kathleen M.; Shaftel, Rebecca; Smol, John P.; Vrede, Tobias; Kahilainen, Kimmo K. (2022)
    Arctic freshwaters are facing multiple environmental pressures, including rapid climate change and increasing land-use activities. Freshwater plankton assemblages are expected to reflect the effects of these stressors through shifts in species distributions and changes to biodiversity. These changes may occur rapidly due to the short generation times and high dispersal capabilities of both phyto- and zooplankton. Spatial patterns and contemporary trends in plankton diversity throughout the circumpolar region were assessed using data from more than 300 lakes in the U.S.A. (Alaska), Canada, Greenland, Iceland, the Faroe Islands, Norway, Sweden, Finland, and Russia. The main objectives of this study were: (1) to assess spatial patterns of plankton diversity focusing on pelagic communities; (2) to assess dominant component of beta diversity (turnover or nestedness); (3) to identify which environmental factors best explain diversity; and (4) to provide recommendations for future monitoring and assessment of freshwater plankton communities across the Arctic region. Phytoplankton and crustacean zooplankton diversity varied substantially across the Arctic and was positively related to summer air temperature. However, for zooplankton, the positive correlation between summer temperature and species numbers decreased with increasing latitude. Taxonomic richness was lower in the high Arctic compared to the sub- and low Arctic for zooplankton but this pattern was less clear for phytoplankton. Fennoscandia and inland regions of Russia represented hotspots for, respectively, phytoplankton and zooplankton diversity, whereas isolated regions had lower taxonomic richness. Ecoregions with high alpha diversity generally also had high beta diversity, and turnover was the most important component of beta diversity in all ecoregions. For both phytoplankton and zooplankton, climatic variables were the most important environmental factors influencing diversity patterns, consistent with previous studies that examined shorter temperature gradients. However, barriers to dispersal may have also played a role in limiting diversity on islands. A better understanding of how diversity patterns are determined by colonisation history, environmental variables, and biotic interactions requires more monitoring data with locations dispersed evenly across the circumpolar Arctic. Furthermore, the importance of turnover in regional diversity patterns indicates that more extensive sampling is required to fully characterise the species pool of Arctic lakes.
  • Mganga, Kevin Z.; Ndathi, Aphaxard J. N.; Wambua, Stephen M.; Bosma, Luwieke; Kaindi, Eric M.; Kioko, Theophilus; Kadenyi, Nancy; Musyoki, Gilbert K.; van Steenbergen, Frank; Musimba, Nashon K. R. (2021)
    Context. Rangeland grasses native to Africa constitute the main diet for free-ranging livestock and wild herbivores. Leaf:stem ratio is a key characteristic used for assessing quality of forages. However, studies to determine the allocation of biomass to leaves and stems as well as chemical components and nutritive value, especially of grasses in African rangelands, are rare. Aim. This study was conducted to establish biomass allocation and chemical and mineral components in leaf and stem fractions of three grasses, Eragrostis superba, Enteropogon macrostachyus and Cenchrus ciliaris, all indigenous to African rangelands. Methods. Plant height, plant densities, plant tiller densities and biomass yields were estimated at the elongation stage, before inflorescence. Chemical and mineral components were determined from biomass harvested at the vegetative phase for all three grass species. Dry matter, ash content, organic matter, crude protein, neutral detergent fibre, acid detergent fibre, acid detergent lignin, and calcium, phosphorus and potassium contents were determined. Key results. Enteropogon macrostachyus displayed significantly greater plant and tiller densities and plant height than the other two species. Leaf and stem biomass fractions varied significantly (P <0.05) among grasses. Leaf:stem ratio of E. superba was double that of E. macrostachyus and C. ciliaris. Crude protein and organic matter yields and net energy for lactation were highest (P <0.05) in E. superba leaf biomass, as was Ca content. Conclusions. Eragrostis superba demonstrated greater potential as a forage species for ruminant animal production than E. macrostachyus and C. ciliaris. Implications. Eragrostis superba is a key forage species that warrants promotion in pasture establishment programs in its native environments.
  • Wasonga, Daniel; Kleemola, Jouko; Alakukku, Laura; Mäkelä, Pirjo (2020)
    Cassava (Manihot esculenta Crantz) experiences intermittent water deficit and suffers from potassium (K) deficiency that seriously constrains its yield in the tropics. Currently, the interaction effect between deficit irrigation and K fertigation on growth and yield of cassava is unknown, especially during the early growth phase. Therefore, pot experiments were conducted under controlled greenhouse conditions using cassava cuttings. Treatments initiated at 30 days after planting included three irrigation doses (30%, 60%, 100% pot capacity) and five K (0.01, 1, 4, 16, and 32 mM) concentrations. The plants were harvested 90 days after planting. Decreasing irrigation dose to 30% together with 16 mM K lowered the leaf water potential by 69%, leaf osmotic potential by 41%, photosynthesis by 35%, stomatal conductance by 41%, water usage by 50%, leaf area by 17%, and whole-plant dry mass by 41%, compared with full-irrigated plants. Lowering the K concentration below 16 mM reduced the values further. Notably, growth and yield were decreased the least compared with optimal, when irrigation dose was decreased to 60% together with 16 mM K. The results demonstrate that deficit irrigation strategies could be utilized to develop management practices to improve cassava productivity by means of K fertigation under low moisture conditions.
  • Tervala, Juha; Watson, Timothy (2022)
    The COVID-19 pandemic initiated a deep global recession, and with interest rates at very low levels, warrants consideration of the efficacy of different forms of fiscal stimulus in response. History reveals that deep recessions may cause output and total factor productivity (TFP) hysteresis, a permanent or highly persistent fall in the levels of output and TFP relative to pre-recession trends. This article analyses the output and welfare multipliers of fiscal stimulus during a recession using a macro model with TFP and output hysteresis. We find that transfer payments, public consumption and investment all have high output and welfare multipliers due to their positive effects on TFP in a recessionary environment. However, public investment has the highest output and welfare multipliers, because it has a more positive impact on labour productivity due to the increase in the public capital stock.(c) 2022 Published by Elsevier Ltd.
  • Pokharel, Kisun; Peippo, Jaana; Honkatukia, Mervi; Seppälä, Arja; Rautiainen, Johanna; Ghanem, Nasser; Hamama, Tuula-Marjatta; Crowe, Mark A.; Andersson, Magnus; Li, Meng-Hua; Kantanen, Juha (2018)
    Background: The highly prolific breeds of domestic sheep (Ovis aries) are globally valuable genetic resources for sheep industry. Genetic, nutritional and other environmental factors affect prolificacy traits in sheep. To improve our knowledge of the sheep prolificacy traits, we conducted mRNA-miRNA integrated profiling of ovarian tissues from two pure breeds with large (Finnsheep) vs. small (Texel) litter sizes and their F1 crosses, half of which were fed a flushing diet. Results: Among the samples, 16,402 genes (60.6% known ovine genes) were expressed, 79 novel miRNAs were found, and a cluster of miRNAs on chromosome 18 was detected. The majority of the differentially expressed genes between breeds were upregulated in the Texel with low prolificacy, owing to the flushing diet effect, whereas a similar pattern was not detected in the Finnsheep. F1 ewes responded similarly to Finnsheep rather than displaying a performance intermediate between the two pure breeds. Conclusions: The identification and characterization of differentially expressed genes and miRNAs in the ovaries of sheep provided insights into genetic and environmental factors affecting prolificacy traits. The three genes (CST6, MEPE and HBB) that were differentially expressed between the group of Finnsheep and Texel ewes kept in normal diet appeared to be candidate genes of prolificacy traits and will require further validation.
  • Rissanen, Kaisa; Martin-Guay, Marc-Olivier; Riopel-Bouvier, Anne-Sophie; Paquette, Alain (2019)
    Biodiversity affects ecosystem functioning in forests by, for example, enhancing growth and altering the forest structure towards greater complexity with cascading effects on other processes and trophic levels. Complexity in forest canopy could enhance light interception and form a link between diversity and productivity in polyculture forests, but the effect of canopy structure on light interception is rarely directly measured. We modelled the canopy surface structure of a tree diversity experiment by photographing it using unmanned aerial vehicle (UAV) and combining the photos into a digital elevation model with photogrammetry tools. We analysed the effects of tree diversity and functional diversity on canopy structural complexity and light interception with a structural equation model. Our results show that: a) increased structural complexity of the canopy reduces light interception, whereas b) tree diversity increases the structural complexity of the canopy, and has a dual impact on light interception. Tree diversity decreased light interception through the structural complexity of the canopy but increased it probably through canopy packing and crown complementarity. However, the effects of both tree diversity and structural complexity of canopy were smaller than the effect of the functional identities of the tree species, especially the differences between deciduous and evergreen trees. We conclude that more complexity in canopy structure can be gained through increased tree diversity, but complex canopy structure does not increase light interception in young forests.