100,943 research outputs found
Moth abundance changes and consequent bottom-up effects on birds in boreal forests
No full textAbstract
Many insect populations are declining, although the exact details of the magnitude and geographic spread of these declines are still unknown. Considering how insects are vital for the functioning of terrestrial ecosystems, evidence of widespread declines has raised concern about cascading effects across trophic levels. The boreal forests of Finland, sources of high-quality long-term monitoring data, offer an ideal setting to expand insect abundance research and explore how climate and environmental change affect insect populations and their trophic interactions. My aim is to investigate (I) how the biomass of moths has changed over time and which ecological and life-history traits could explain these trends, (II) whether moth biomass has a bottom-up effect on insectivorous forest birds at the functional group level, and (III) whether such bottom-up effects can be detected at the species level. I used state-of-the-art joint dynamic species distribution models (JDSDMs) to address the aims. My results suggest that: (I) there has been no decline in the total biomass of moth functional groups across Finland in the past 27 years. Instead, biomass remained stable for most groups, while several were increasing. There was also considerable geographical variation in abundance trends. (II) Abundance fluctuations of insectivorous forest birds were positively associated with fluctuations in moth biomass, particularly among early-season moths in the north-boreal zone, where seasonal constraints on breeding are most pronounced. These bottom-up effects were observed for birds that were residents or long-distance migrants. The strength of these associations declined towards the south, indicating regional variation in the strength of trophic interactions. (III) At the species level, moth bottom-up effects on birds were generally weak and inconsistent, with a few weak but biologically meaningful patterns emerging in the north-boreal zone. The unexpectedly weak bottom-up effects indicate that forest birds may possess greater foraging flexibility and resilience than previously assumed, enabling them to cope with fluctuations in specific prey resources. This dissertation emphasizes how integrating long-term biodiversity datasets can reveal community-level trophic interactions and provide new opportunities for understanding the effects of global change on ecosystem functioning. Original papers Yazdanian, M., Kankaanpää, T., Itämies, J., Leinonen, R., Merckx, T., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2023). Ecological and life‐history traits predict temporal trends in biomass of boreal moths. Insect Conservation and Diversity, 16(5), 600–615. https://doi.org/10.1111/icad.12657 https://doi.org/10.1111/icad.12657 Self-archived version Yazdanian, M., Kankaanpää, T., Merckx, T., Huikkonen, I., Itämies, J., Jokimäki, J., Lehikoinen, A., Leinonen, R., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2024). Evidence for bottom‐up effects of moth abundance on forest birds in the north‐boreal zone alone. Ecology Letters, 27(12), e14467. https://doi.org/10.1111/ele.14467 https://doi.org/10.1111/ele.14467 Self-archived version Yazdanian, M., Kankaanpää, T., Merckx, T., Huikkonen, I. M., Itämies, J., Jokimäki, J., Lehikoinen, A., Leinonen, R., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2024). Assessment of bottom-up effects of moths on population dynamics of forest birds. Manuscript in preparation. Tiivistelmä
Hyönteispopulaatioiden on maailmanlaajuisesti havaittu taantuneen voimakkaasti. Koska hyönteiset suorittavat kriittisiä toimintoja maaekosysteemeissä, havainnot niiden laajamittaisesta vähenemisestä ovat herättäneet huolta mahdollisista trofiatasojen välisistä kerrannaisvaikutuksista. Tästä huolimatta tiedot hyönteisrunsauksien pitkäaikaismuutoksista tai niiden vaikutuksista ovat puutteellisia jopa hyönteistuntemukseltaan edistyksellisessä pohjolassa. Suomen boreaalisista metsistä kerättyjen pitkien seuranta-aineistojen avulla voidaan tutkia ilmaston- ja ympäristönmuutosten vaikutuksia hyönteisrunsauksiin ja hyönteisten rooleihin ravintoverkoissa. Tutkin (I) miten yöperhosten biomassa on muuttunut viime vuosikymmeninä, sekä mitkä ekologiset- tai elinkierto-ominaisuudet selittävät lajienvälisiä eroja runsausmuutoksissa; (II) säätelevätkö yöperhosryhmien runsausvaihtelut metsälintujen pesimätiheyksiä, kun tarkastellaan lintuja joko niiden lajiominaisuuksien perusteella ryhmiteltyinä, tai (III) lajikohtaisesti. Käytin yhteisöekologian uusimpia ja väkevimpiä työkaluja, dynaamisia lajien yhteisesiintymismalleja (JDSDM). Tulosteni mukaan (I) minkään tutkimani yöperhosryhmän kokonaisbiomassa ei ole vähentynyt koko Suomen mittakaavassa viimeisten 27 vuoden aikana. Perhosryhmien sisällä tiheysmuutoksissa oli kuitenkin suurtakin maantieteellistä vaihtelua. (II) Yöperhosten, ja etenkin kasvukauden alussa toukkana esiintyvien lajien runsausvaihtelut selittivät seuraavan vuoden lintujen pesimätiheyksiä varsinkin pohjoisboreaalisella metsävyöhykkeellä. Yöperhosravinnon saatavuus vaikutti etenkin paikkalintujen sekä pitkänmatkan muuttajien pesimätiheyksiin. Vaikutusten heikkeneminen siirryttäessä eteläisemmille vyöhykkeille osoittaa maantieteellistä muuntelua ravintoverkkovuorovaikutusten voimakkuuksissa. (III) Yöperhosravinnon saatavuuden vaikutukset yksittäisten lintulajien pesimätiheyksiin olivat pääasiassa heikkoja ja epäjohdonmukaisia, muutamia pohjoisboreaalisella alueella havaittuja biologisesti mielekkäitä yhteyksiä lukuun ottamatta. Voimakkaiden yhteyksien puuttuminen voi tarkoittaa, että metsälinnut saattavat olla ravinnonhankinnassaan joustavampia kuin on yleisesti ajateltu, mikä helpottaisi niitä selviämään tiettyjen saaliseläinten runsausnotkahduksista. Tämä väitöstutkimus korostaa kuinka yhdistelemällä seuranta-aineistoja voimme paljastaa, miten lajienväliset vuorovaikutukset vaikuttavat eliöyhteisöjen muuttumiseen maailmanlaajuisten ympäristömuutosten seurauksena. Osajulkaisut Yazdanian, M., Kankaanpää, T., Itämies, J., Leinonen, R., Merckx, T., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2023). Ecological and life‐history traits predict temporal trends in biomass of boreal moths. Insect Conservation and Diversity, 16(5), 600–615. https://doi.org/10.1111/icad.12657 https://doi.org/10.1111/icad.12657 Rinnakkaistallennettu versio Yazdanian, M., Kankaanpää, T., Merckx, T., Huikkonen, I., Itämies, J., Jokimäki, J., Lehikoinen, A., Leinonen, R., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2024). Evidence for bottom‐up effects of moth abundance on forest birds in the north‐boreal zone alone. Ecology Letters, 27(12), e14467. https://doi.org/10.1111/ele.14467 https://doi.org/10.1111/ele.14467 Rinnakkaistallennettu versio Yazdanian, M., Kankaanpää, T., Merckx, T., Huikkonen, I. M., Itämies, J., Jokimäki, J., Lehikoinen, A., Leinonen, R., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2024). Assessment of bottom-up effects of moths on population dynamics of forest birds. Manuscript in preparation. Academic dissertation to be presented with the assent of the Doctoral Programme Committee of Technology and Natural Sciences of the University of Oulu for public defence in the OP-Pohjola auditorium (L6), Linnanmaa, on 22 August 2025, at 12 noonAbstract
Many insect populations are declining, although the exact details of the magnitude and geographic spread of these declines are still unknown. Considering how insects are vital for the functioning of terrestrial ecosystems, evidence of widespread declines has raised concern about cascading effects across trophic levels. The boreal forests of Finland, sources of high-quality long-term monitoring data, offer an ideal setting to expand insect abundance research and explore how climate and environmental change affect insect populations and their trophic interactions. My aim is to investigate (I) how the biomass of moths has changed over time and which ecological and life-history traits could explain these trends, (II) whether moth biomass has a bottom-up effect on insectivorous forest birds at the functional group level, and (III) whether such bottom-up effects can be detected at the species level. I used state-of-the-art joint dynamic species distribution models (JDSDMs) to address the aims. My results suggest that: (I) there has been no decline in the total biomass of moth functional groups across Finland in the past 27 years. Instead, biomass remained stable for most groups, while several were increasing. There was also considerable geographical variation in abundance trends. (II) Abundance fluctuations of insectivorous forest birds were positively associated with fluctuations in moth biomass, particularly among early-season moths in the north-boreal zone, where seasonal constraints on breeding are most pronounced. These bottom-up effects were observed for birds that were residents or long-distance migrants. The strength of these associations declined towards the south, indicating regional variation in the strength of trophic interactions. (III) At the species level, moth bottom-up effects on birds were generally weak and inconsistent, with a few weak but biologically meaningful patterns emerging in the north-boreal zone. The unexpectedly weak bottom-up effects indicate that forest birds may possess greater foraging flexibility and resilience than previously assumed, enabling them to cope with fluctuations in specific prey resources. This dissertation emphasizes how integrating long-term biodiversity datasets can reveal community-level trophic interactions and provide new opportunities for understanding the effects of global change on ecosystem functioning.Tiivistelmä
Hyönteispopulaatioiden on maailmanlaajuisesti havaittu taantuneen voimakkaasti. Koska hyönteiset suorittavat kriittisiä toimintoja maaekosysteemeissä, havainnot niiden laajamittaisesta vähenemisestä ovat herättäneet huolta mahdollisista trofiatasojen välisistä kerrannaisvaikutuksista. Tästä huolimatta tiedot hyönteisrunsauksien pitkäaikaismuutoksista tai niiden vaikutuksista ovat puutteellisia jopa hyönteistuntemukseltaan edistyksellisessä pohjolassa. Suomen boreaalisista metsistä kerättyjen pitkien seuranta-aineistojen avulla voidaan tutkia ilmaston- ja ympäristönmuutosten vaikutuksia hyönteisrunsauksiin ja hyönteisten rooleihin ravintoverkoissa. Tutkin (I) miten yöperhosten biomassa on muuttunut viime vuosikymmeninä, sekä mitkä ekologiset- tai elinkierto-ominaisuudet selittävät lajienvälisiä eroja runsausmuutoksissa; (II) säätelevätkö yöperhosryhmien runsausvaihtelut metsälintujen pesimätiheyksiä, kun tarkastellaan lintuja joko niiden lajiominaisuuksien perusteella ryhmiteltyinä, tai (III) lajikohtaisesti. Käytin yhteisöekologian uusimpia ja väkevimpiä työkaluja, dynaamisia lajien yhteisesiintymismalleja (JDSDM). Tulosteni mukaan (I) minkään tutkimani yöperhosryhmän kokonaisbiomassa ei ole vähentynyt koko Suomen mittakaavassa viimeisten 27 vuoden aikana. Perhosryhmien sisällä tiheysmuutoksissa oli kuitenkin suurtakin maantieteellistä vaihtelua. (II) Yöperhosten, ja etenkin kasvukauden alussa toukkana esiintyvien lajien runsausvaihtelut selittivät seuraavan vuoden lintujen pesimätiheyksiä varsinkin pohjoisboreaalisella metsävyöhykkeellä. Yöperhosravinnon saatavuus vaikutti etenkin paikkalintujen sekä pitkänmatkan muuttajien pesimätiheyksiin. Vaikutusten heikkeneminen siirryttäessä eteläisemmille vyöhykkeille osoittaa maantieteellistä muuntelua ravintoverkkovuorovaikutusten voimakkuuksissa. (III) Yöperhosravinnon saatavuuden vaikutukset yksittäisten lintulajien pesimätiheyksiin olivat pääasiassa heikkoja ja epäjohdonmukaisia, muutamia pohjoisboreaalisella alueella havaittuja biologisesti mielekkäitä yhteyksiä lukuun ottamatta. Voimakkaiden yhteyksien puuttuminen voi tarkoittaa, että metsälinnut saattavat olla ravinnonhankinnassaan joustavampia kuin on yleisesti ajateltu, mikä helpottaisi niitä selviämään tiettyjen saaliseläinten runsausnotkahduksista. Tämä väitöstutkimus korostaa kuinka yhdistelemällä seuranta-aineistoja voimme paljastaa, miten lajienväliset vuorovaikutukset vaikuttavat eliöyhteisöjen muuttumiseen maailmanlaajuisten ympäristömuutosten seurauksena
On The Susceptibility of PID in Perovskite Modules: A Comparison of ITO and Cu Contacts
No full textOrganic-inorganic perovskite lead halide solar cells (PSCs) have received increasing interest in the last decade. PSCs already achieve record efficiencies above 25%. However, long-term stability is still a problem, especially when transitioning from cells to modules.
One of the described long-term stability problems at the module level is Potential-induced degradation (PID), caused by the voltage build-up by modules connected in series.
PID is extensively investigated within crystalline silicon PV, while very little is known for perovskites. Carolus et al. reported nearly complete efficiency losses within 18 hours of a PID stress test, indicating their high susceptibility to PID[1]. In order to tackle PID-related stability issues and make commercialization a reality, it is crucial to retrieve insights into the physics of the PID mechanism.
This study investigates and compares the PID mechanism within p-i-n CsFAPbIBr perovskite modules with either a copper (Cu) or an indium tin oxide (ITO) rear contact. Several soda-lime glass-glass configured 5.5 x 5.5 cm² mini-modules were PID stressed from the p-side at 40⁰C and 1000 V for 192 hours using the foil method. Intermediate current-voltage measurements (IV) and electroluminescence (EL) images were taken to investigate the PID progress.
The ITO contacted perovskite modules illustrate an incubation period of about 100 hours. A slight drop in short-circuit current (Isc) and a modest increase in series resistance can be observed within this incubation period.
Subsequently, a significant drop in Isc and increase in series resistance are noticeable. Evidently, after 192 hours, an additional decrease in shunt resistance is noticeable, resulting in a total relative loss of efficiency of almost 80%. The EL images illustrate no significant differences in the incubation period, although the formation of inhomogeneities can be observed further in the degradation process[2].
The Cu-contacted perovskite modules are significantly more prone to PID than their ITO counterpart. Similarly, the drop in Isc and increase in series resistance can be observed; however, no incubation period is present.
Analogous to crystalline silicon, it is hypothesized that positively charged sodium ions migrate out of the cover glass towards the PV cell. Hence, the ions can alter the conductivity of the contacts or migrate deeper into the stack and form inhomogeneities in the perovskite material[3]. However, additional PID stress tests are ongoing to validate the hypothesized findings. Furthermore, microstructural analysis is necessary to designate this degradation mechanism's root cause and retrieve more insights into its physical behavior and kinetics
On The Susceptibility of PID in Perovskite Modules: A Comparison of ITO and Cu Contacts
No full textOrganic-inorganic perovskite lead halide solar cells (PSCs) have received increasing interest in the last decade. PSCs already achieve record efficiencies above 25%. However, long-term stability is still a problem, especially when transitioning from cells to modules.
One of the described long-term stability problems at the module level is Potential-induced degradation (PID), caused by the voltage build-up by modules connected in series.
PID is extensively investigated within crystalline silicon PV, while very little is known for perovskites. Carolus et al. reported nearly complete efficiency losses within 18 hours of a PID stress test, indicating their high susceptibility to PID[1]. In order to tackle PID-related stability issues and make commercialization a reality, it is crucial to retrieve insights into the physics of the PID mechanism.
This study investigates and compares the PID mechanism within p-i-n CsFAPbIBr perovskite modules with either a copper (Cu) or an indium tin oxide (ITO) rear contact. Several soda-lime glass-glass configured 5.5 x 5.5 cm² mini-modules were PID stressed from the p-side at 40⁰C and 1000 V for 192 hours using the foil method. Intermediate current-voltage measurements (IV) and electroluminescence (EL) images were taken to investigate the PID progress.
The ITO contacted perovskite modules illustrate an incubation period of about 100 hours. A slight drop in short-circuit current (Isc) and a modest increase in series resistance can be observed within this incubation period.
Subsequently, a significant drop in Isc and increase in series resistance are noticeable. Evidently, after 192 hours, an additional decrease in shunt resistance is noticeable, resulting in a total relative loss of efficiency of almost 80%. The EL images illustrate no significant differences in the incubation period, although the formation of inhomogeneities can be observed further in the degradation process[2].
The Cu-contacted perovskite modules are significantly more prone to PID than their ITO counterpart. Similarly, the drop in Isc and increase in series resistance can be observed; however, no incubation period is present.
Analogous to crystalline silicon, it is hypothesized that positively charged sodium ions migrate out of the cover glass towards the PV cell. Hence, the ions can alter the conductivity of the contacts or migrate deeper into the stack and form inhomogeneities in the perovskite material[3]. However, additional PID stress tests are ongoing to validate the hypothesized findings. Furthermore, microstructural analysis is necessary to designate this degradation mechanism's root cause and retrieve more insights into its physical behavior and kinetics
Hedgerow trees and extended-width field margins enhance macro-moth diversity: implications for management
No full textImproving the effectiveness of agri-environment schemes is essential for reversing declines in farmland biodiversity. Crucial to achieving this is identifying management options that are practical and beneficial to biodiversity, and understanding the influence of the surrounding landscape. We used data on abundance and species richness of farmland macro-moths, many of which are declining, and trait-based analyses on their feeding guild, mobility and conservation status, to explore local- and landscape-scale effects of two farmland features (extended-width field margins and hedgerow trees) and surrounding farmland intensification. Macro-moths were light trapped at 48 fixed sites on 16 farms, over 4 years, within a 1200-km2 area of lowland UK farmland. Sites belonged to one of four experimental groups that differed in their combinations of hedgerow tree presence and field margin width. Hedgerow trees and extended-width field margins locally increased species richness, but not abundance, of macro-moths, irrespective of each other's presence. Overall, species richness and abundance were not affected by agricultural intensification, as measured by the amount of arable land in the surrounding landscape. Sedentary moths showed double the species richness, but were half as abundant as mobile moths. Both groups responded positively to extended-width margin and hedgerow tree presence. The effect of hedgerow trees was particularly strong for shrub- and/or tree-feeding species. Analyses based on the conservation status of moths demonstrated that agricultural intensification lowered the species richness of nationally severely declining UK Biodiversity Action Plan priority species and the abundance of both nationally moderately declining and priority species. These effects were most pronounced at the 0·8-km radius scale. Synthesis and applications. Our results suggest that the presence of extended-width field margins and hedgerow trees, possibly promoted by agri-environment schemes targeting their implementation at relatively small spatial scales (0·8 km), may help mitigate negative effects of agricultural intensification on macro-moths. A wide range of other taxa feed on macro-moths and may therefore indirectly benefit from these features. Nevertheless, taxa differ widely in their mobility and measures mitigating biodiversity loss may need to be targeted at multiple spatial scales to maximize their effectiveness for multiple taxa. Our results suggest that the presence of extended-width field margins and hedgerow trees, possibly promoted by agri-environment schemes targeting their implementation at relatively small spatial scales (0·8 km), may help mitigate negative effects of agricultural intensification on macro-moths. A wide range of other taxa feed on macro-moths and may therefore indirectly benefit from these features. Nevertheless, taxa differ widely in their mobility and measures mitigating biodiversity loss may need to be targeted at multiple spatial scales to maximize their effectiveness for multiple taxa. © 2012 British Ecological Society
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
Handwritten biographical information on Paulina T. McClung Merritt
No full textA handwritten biography of Paulina T. McClung Merritt by an unknown author, 1892.
Heterogeneous and tissue-specific regulation of effector T cell responses by IFN-gamma during Plasmodium berghei ANKA infection.
No full textIFN-γ and T cells are both required for the development of experimental cerebral malaria during Plasmodium berghei ANKA infection. Surprisingly, however, the role of IFN-γ in shaping the effector CD4(+) and CD8(+) T cell response during this infection has not been examined in detail. To address this, we have compared the effector T cell responses in wild-type and IFN-γ(-/-) mice during P. berghei ANKA infection. The expansion of splenic CD4(+) and CD8(+) T cells during P. berghei ANKA infection was unaffected by the absence of IFN-γ, but the contraction phase of the T cell response was significantly attenuated. Splenic T cell activation and effector function were essentially normal in IFN-γ(-/-) mice; however, the migration to, and accumulation of, effector CD4(+) and CD8(+) T cells in the lung, liver, and brain was altered in IFN-γ(-/-) mice. Interestingly, activation and accumulation of T cells in various nonlymphoid organs was differently affected by lack of IFN-γ, suggesting that IFN-γ influences T cell effector function to varying levels in different anatomical locations. Importantly, control of splenic T cell numbers during P. berghei ANKA infection depended on active IFN-γ-dependent environmental signals--leading to T cell apoptosis--rather than upon intrinsic alterations in T cell programming. To our knowledge, this is the first study to fully investigate the role of IFN-γ in modulating T cell function during P. berghei ANKA infection and reveals that IFN-γ is required for efficient contraction of the pool of activated T cells
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Pelevin’s Trinity in the novel “t”: author – protagonist – reader
No full textThe article attempts to interpret Pelevin's artistic strategy in the novel "T" by exploring its subject organization and addressing the key problems of the author, the protagonist, and the reader as they are seen by the researcher. The article analyzes the peculiarities of constructing the narrative reality in the novel "T", and goes on to discuss Pelevin's philosophic models of the development of the humankind, and the emergence of his new anthropology
- …
