Browsing by Subject "biomass"
Now showing items 1-6 of 6
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(2024)Kaupunkien ilmastotavoitteiden saavuttaminen edellyttää päästöjen vähentämistä, mutta myös kaupunkien kas-villisuuden hiilivarastojen kasvattamista. Kaupunkikasvillisuuden hiilivarastojen tutkimus on kuitenkin vähäistä ja erityisesti kaupunkipensaiden on puutteellista. Pensaat ovat kuitenkin yksi käytetyimmistä kasvillisuustyy-peistä kaupunkialueilla, ja sen vuoksi niiden hiilivarastojen selvittäminen on tärkeää. Tässä tutkimuksessa tien-pientareet on tunnistettu potentiaalisiksi alueiksi kasvattaa Helsingin kaupungin kasvillisuuden hiilenvarastoja. Tienpientareilla kasvaa usein nurmikkoa, jolla on heikko hiilenvarastointikyky. Tämän takia tässä tutkimuksessa ehdotetaan tienpientareilla kasvavien nurmikoiden vaihtamista pieniin pensaisiin, jotta hiilenvarastointikapasi-teettia voitaisiin kasvattaa. Tässä tutkimuksessa käytettiin kuivapainomittausmenetelmää kymmenen eri kaupunkipensaslajin kuivapainojen ja hiilenvarastojen mittaamiseksi. Tutkimuksessa tarkasteltiin myös pensaiden biomassan jakautumista ylä- ja alapuolisten osien välillä. Lisäksi tässä tutkimuksessa tutkittiin mahdollisuutta käyttää pensaiden kokoindeksiä niiden biomassan arvioinnissa, mikä voisi nopeuttaa pensaiden hiilivarastojen tutkimusta tulevaisuudessa. Tämän lisäksi tässä tutkimuksessa laskettiin, kuinka paljon enemmän hiiltä saataisiin varastoitua, jos kaikki Helsingin tienpientareiden nurmikot vaihdettaisiin pieniin pensaisiin. Kolmen tapausesimerkin avulla laskettiin tarkempi pinta-ala, johon pensaat voitaisiin istuttaa, ja siten myös tarkempi hiilenvarasto. Tapausesimerkeissä huomioitiin tieturvallisuuden asettamat rajoitteet pensasistutuksille. Pensaiden hiilenvarastot vaihtelivat merkittävästi eri lajien välillä. Suurimmalla osalla pensaista biomassaa oli eniten yläpuolisissa osissa, mutta oli myös lajeja, joilla juuret muodostivat suurimman osan biomassaa. Kaikista tutkituista pensaista 75 %:lla havaittiin korrelaatiota kokoindeksin ja biomassan välillä. Helsingin tienpientareet, joissa kasvaa nurmikkoa, kattavat yli 1 % kaupungin maapinta-alasta. Jos koko tutkimusalueen nurmikot vaih-dettaisiin pieniksi pensaiksi, hiilen varasto kasvaisi yli 23-kertaiseksi. Tapausesimerkkialueilta saatiin pensaiden osalta yhtä lupaavia tuloksia, vaikka niiden pinta-aloja oli pienennetty. Nurmikot kattavat suuren osan kaupunkien avoimista viheralueista. Niiden käyttäminen nykyisellä mittakaavalla on kuitenkin tarpeetonta, vaikka ne tarjoavatkin tärkeitä hyötyjä kuten avarat tilat ja estetiikkaa. Pensaiden istut-taminen tienvarsille lisäisi aluksi kustannuksia, mutta pitkällä aikavälillä se voisi johtaa kunnossapitosäästöihin, sillä pensaat eivät vaadi jatkuvaa leikkaamista niin kuin nurmikot. Lisäksi pensaiden käyttäminen tienvarsilla tuottaisi monipuolisempia ekosysteemipalveluita verrattuna nurmikoihin, mikä mahdollistaisi paremman sopeu-tumisen ilmastonmuutoksen vaikutuksiin.
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(2023)Arctic ecosystems face drastic changes in community structure due to warming, shrubification, permafrost loss, and other environmental changes. Due to the spatial heterogeneity of these ecosystems, understanding such changes on a local scale requires high-resolution data. Earth observation using satellite imagery and aerial photography has become a staple in mapping large areas and general patterns. Advances in sensor technology, the proliferation of unmanned aerial vehicles (UAVs), and increases in processing capacity enable the use of higher spatial and spectral resolutions. As a result, more detailed ecological observations can be made using remote sensing methods. In this thesis, I assess how increased spectral resolution affects the remote-sensing based modelling of plant communities in low-growth oroarctic tundra heaths. Based on a large field observation dataset, I estimate biomass, leaf area index, species richness, Shannon's biodiversity index, and fuzzy community clusters. I then build random forest models of these with image data of varying spectral, spatial, and temporal specifications and topographical data. Finally, I create maps of the vegetation. Leaf area index and biomass are best estimated of the response variables, with R2 values of 0.64 and 0.59, respectively, with multispectral data proving the most important explanatory dataset. Biodiversity metrics are best estimated with R2 values of 0.40–0.50 with the most important explanatory variables being topographical and hyperspectral, and community cluster with R2 values of 0.27–0.53, with the importance of various explanatory variables depending on the cluster being estimated. These results can help choose a suitable high-resolution remote sensing approach for modelling plant communities in similar conditions.
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(2022)Cyanobacteria are an important part of the phytoplankton community and aquatic ecosystems. Cyanobacteria can form large mass occurrences, i.e. blooms, which can be toxic or cause other harm. Research and monitoring of cyanobacteria has been based on microscopy analysis. However, molecular-based methods, such as 16S rRNA sequencing are replacing microscopy analyses in the near future. The Finnish Environment Institute has stated that molecular methods are part of environmental monitoring before 2030. In this Master’s thesis the aim was to determine whether conventional microscopy analyses and 16S rRNA sequencing differ when comparing nano- and micro-sized cyanobacteria. The material was collected from a laboratory experiment of the Finnish Environment Institute’s (SYKE) MiDAS project, which was conducted in the summer of 2020. The results of the microscopy and 16S rRNA analyses differed from each other. The relative abundances of the cyanobacteria genera differed between sample types. Microscopy analyses estimated that the alpha diversity was higher compared to the results of the sequencing analyses. The main reason for the difference between the types of analyses was due to the differences in cyanobacteria belonging to the order of Synechococcales. Some of the Synechococcales species were observed only by the sequencing analyses, e.g. Snowella and some of the Synechococcales species were only observed by the microscopy analyses, e.g. Romeria and Woronichinia. It was observed that both methods are prone to identification errors. The differences between the 16S rRNA sequencing and the microscopy analyses are vastly different. It may affect on the review of long-term data of the phytoplankton community. Therefore, it is important to examine the differences between the types of analyses. Studying the dissimilarities between the types of analyses should be focused on the research of the small cell-sized colonial cyanobacteria, i.e. the species of Chroococcales and Synechococcales.
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(2021)The science of fish stock assessment is one that is very resource and labor intensive, with stock assessment models historically being based on data that causes a model to overestimate the strength of a population, sometimes with drastic consequences. The need of cost-effective assessment models and approaches increases, which is why I looked into using Bayesian modeling and networks as an approach not often used in fisheries science. I wanted to determine if it could be used to predict both recruitment and spawning stock biomass of four fish species in the north Atlantic, cod, haddock, pollock and capelin, based on no other evidence other than the recruitment or biomass data of the other species and if these results could be used to lower the uncertanties of fish stock models. I used data available on the RAM legacy database to produce four different models with the statistical software R, based on four different Bayes algorithms found in the R-package bnlearn, two based on continuous data and two based on discrete data. What I found was that there is much potential in the Bayesian approach to stock prediction and forecasting, as our prediction error percentage ranged between 1 and 40 percent. The best predictions were made when the species used as evidence had a high correlation coefficient with the target species, which was the case with cod and haddock biomass, which had a unusually high correlation of 0.96. As such, this approach could be used to make preliminary models of interactions between a high amount of species in a specific area, where there is data abundantly available and these models could be used to lower the uncertanties of the stock assessments. However, more research into the applicability for this approach to other species and areas needs to be conducted.
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(2024)As global temperatures rise due to anthropogenic greenhouse gas emissions, it is becoming increasingly important to mitigate climate change. Agriculture, one of the major contributors to greenhouse gas emissions, has the potential for mitigation by implementing carbon sequestration practices. Biochars, carbon-rich materials derived from biomass pyrolysis, have drawn attention for their potential to sequester carbon and enhance crop growth. However, limited yield effects have been reported in boreal agricultural soils after applying pure biochars to soils. Therefore, application of activated and nutrient enriched biochar has been proposed as an amendment for getting most use of the practice due to slow release of nutrients and carbon sequestration. However, the effects of these new activated biochars on soil biota remain unknown. The study investigates the impact of acid and slurry activated biochar on earthworm community in agricultural soil in southern Finland, focusing on their implications for soil physical properties and ecosystem health. Through a split-plot designed field experiment, with biochar (applied at rate 0 t ha-1 and 20 t ha-1) being the main factor and fertilizer level the sub-plot factor, the interaction between nutrient enriched biochar and earthworm population was examined by assessing earthworms' abundance, biomass, and mean weight. There was no significant effect of the treatments on earthworm abundance, biomass, or mean weight. However, the mean weight showed a notable response to the interaction effect of biochar x fertiliser. Biomass and mean weight were negatively correlated by temperature. Among the other variables, soil water content had positive correlation with temperature. These findings highlight a possible association influenced by soil physicochemical parameters, microbial dynamics, and environmental conditions, even though biochar had no apparent impacts on earthworm density, biomass, or mean weight. In this first-ever field experiment with a high rate of acid and slurry-activated biochar applied to agricultural soil, biochar had no adverse effect on earthworm populations. Thus, the present findings confirm that the application of large amounts of biochar treated with acid and cattle slurry in Nordic agricultural soil is a safe C sequestration method for earthworms at least for a short time period. However, the long-term effect is still a knowledge gap. Addressing this knowledge gap is crucial to apply sustainable agriculture methods that enhance soil properties and health.
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(2021)Improving land management to mitigate climate change is important, especially in agriculture on soils with high organic content. Many studies have found evidence that increasing diversity can help to improve plant biomass production and soil carbon storage. This is attributed to complementarity which consists of more efficient resource use due to niche differences and facilitative interactions. For the total climate impact, the effect of greenhouse gas emissions from the soil needs to be considered. To find out if adding more species to a grass mixture could have similar benefits in boreal zone grass cultivation in Finland, an experiment was set up with four different species mixtures, and three levels of species richness were established under a nurse crop. It was additionally of interest if these effects can counter the emissions of cultivation on organic soils. Biomass samples were collected both before the nurse crop was removed and at the end of the growing season. Both species richness and Shannon diversity index were considered as explanatory factors. Carbon exchange, divided into respiration and photosynthetic capacity, as well as nitrous oxide and methane fluxes, were monitored monthly. There was no strong evidence that species richness affects biomass or greenhouse gas fluxes during the first year. The effect of species richness on the biomass was clearer when the diversity index was considered. These results were significant when the lowest biomass values were excluded from the analysis, probably because complementary resource use needs enough biomass to have an effect. The differences in carbon flux measurements may be sensitive to timing within the growing season since the results closest to significant were obtained at the start of the season. At the time, the measurement conditions were good and the nurse crop biomass was small enough not to obscure the effects of grass mixture. When it comes to other greenhouse gases, species richness had most impact on early nitrous oxide emissions, while methane flux probably needs significantly more time for any changes to appear. Overall, the effect of species richness needs to be studied over the full grass cultivation cycle to find out the full effect. Based on current results, increasing species richness may be an option when other methods cannot be used to reduce emissions and improve carbon sink of agriculture.
Now showing items 1-6 of 6