Browsing by Subject "LANDSCAPE STRUCTURE"
Now showing items 1-6 of 6
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(2018)Climate change presents a serious threat to global biodiversity. Loss of pollinators in particular has major implications, with extirpation of these species potentially leading to severe losses in agriculture and, thus, economic losses. In this study, we forecast the effects of climate change on the distribution of hoverflies in Southeast Europe using species distribution modelling and climate change scenarios for two time-periods. For 2041-2060, 19 analysed species were predicted to increase their areas of occupancy, with the other 25 losing some of their ranges. For 2061-2080, 55% of species were predicted to increase their area of occupancy, while 45% were predicted to experience range decline. In general, range size changes for most species were below 20%, indicating a relatively high resilience of hoverflies to climate change when only environmental variables are considered. Additionally, range-restricted species are not predicted to lose more area proportionally to widespread species. Based on our results, two distributional trends can be established: the predicted gain of species in alpine regions, and future loss of species from lowland areas. Considering that the loss of pollinators from present lowland agricultural areas is predicted and that habitat degradation presents a threat to possible range expansion of hoverflies in the future, developing conservation management strategy for the preservation of these species is crucial. This study represents an important step towards the assessment of the effects of climate changes on hoverflies and can be a valuable asset in creating future conservation plan, thus helping in mitigating potential consequences.
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(2018)Protected areas are meant to preserve native local communities within their boundaries, but they are not independent from their surroundings. Impoverished habitat quality in the matrix might influence the species composition within the protected areas through biotic homogenization. The aim of this study was to determine the impacts of matrix quality on species richness and trait composition of bird communities from the Finnish reserve area network and whether the communities are being subject of biotic homogenization due to the lowered quality of the landscape matrix. We used joint species distribution modeling to study how characteristics of the Finnish forest reserves and the quality of their surrounding matrix alter species and trait compositions of forest birds. The proportion of old forest within the reserves was the main factor in explaining the bird community composition, and the bird communities within the reserves did not strongly depend on the quality of the matrix. Yet, in line with the homogenization theory, the beta-diversity within reserves embedded in low-quality matrix was lower than that in high-quality matrix, and the average abundance of regionally abundant species was higher. Influence of habitat quality on bird community composition was largely explained by the species' functional traits. Most importantly, the community specialization index was low, and average body size was high in areas with low proportion of old forest. We conclude that for conserving local bird communities in northern Finnish protected forests, it is currently more important to improve or maintain habitat quality within the reserves than in the surrounding matrix. Nevertheless, we found signals of bird community homogenization, and thus, activities that decrease the quality of the matrix are a threat for bird communities.
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(2019)Ecological intensification has been proposed as a strategy to mitigate the impacts of conventional intensive land use on pollinators and insect pollination. However, research has concentrated on the effects of land management on pollinator abundance and diversity, while studies directly measuring pollination services are still lacking for many crops and regions. This study examines the effects of landscape heterogeneity, pesticide use intensity and flowering time on insect pollination of turnip rape Brassica rapa ssp. oleifera, a major oil crop at high latitudes. The field experiment included monitoring pollinator visits on turnip rape flowers and measuring yield in 34 spring-sown turnip rape fields in Southern Finland. The fields were situated in two landscape types that differed in the cover of arable land and represented independent gradients of pesticide use intensity and flowering time. Based on flower visits and number of seeds per silique, turnip rape was best pollinated in fields with late flowering time. The result suggests a temporal mismatch between crop flowering and the availability of pollination service in early sown fields. The increase in flower visits during summer was steeper among fields with low than high pesticide use, possibly due to a faster colony growth of important bee pollinators. Pollinator community in turnip rape fields was more diverse in heterogeneous landscapes with less arable land than in homogeneous field-dominated landscapes, suggesting higher stability of pollination services in diverse landscapes. Total yield per plant was positively related to pesticide use intensity. The relationship between insect pollination and total yield was weakened by high compensation capacity of turnip rape, the plants producing more flowers under poor pollination.Synthesis and applications. Crop pollination can be enhanced by shifting sowing time to better match crop flowering to the peak availability of the most important pollinators. Reduced pesticide use may also enhance pollination services but can lead to the total yield reduction due to pests. This highlights the need for pollinator-friendly pest control methods to maintain turnip rape yields while conserving pollination services. Foreign Language AbstractTiivistelma Maatalouden ekologista tehostamista on esitetty strategiaksi, jonka avulla intensiivisen maankayton kielteisia vaikutuksia polyttajiin ja hyonteispolytykseen voidaan hillita. Tutkimukset maankayton vaikutuksista viljelykasvien hyonteispolytykseen kuitenkin puuttuvat yha monilta viljelykasveilta ja alueilta. Tama tutkimus tarkasteli maiseman monimuotoisuuden, torjunta-aineiden kayton ja kukinta-ajan vaikutusta rypsin hyonteispolytykseen. Peltokokeessa seurattiin polyttajien vierailuja rypsin kukilla ja mitattiin satoa 34 kevatrypsipellolla Uudellamaalla. Pellot sijaitsivat kahdessa maisematyypissa, joista toinen oli peltovaltainen ja toinen monimuotoisempi ja vahemman peltoa sisaltava. Lisaksi pellot erosivat toisistaan torjunta-aineiden kayton ja kukinta-ajan suhteen. Polyttajien kukkavierailut ja siementen maara per litu olivat korkeimmillaan myohaan kukkineilla rypsipelloilla, mika kertoo hyvasta polytyksesta. Tuloksen perusteella aikaisin kylvetyt rypsipellot saattavat kukkia liian aikaisin polyttajien saatavuuden nakokulmasta. Voimakkaimmin polyttajien maara lisaantyi kesan aikana niiden peltojen joukossa, joilla ei kaytetty torjunta-aineita. Mahdollinen selitys on, etta tarhamehilaisten ja kimalaisten yhdyskunnat kasvoivat nopeimmin naiden peltojen laheisyydessa. Polyttajien monimuotoisuus oli suurempi monimuotoisessa kuin peltovaltaisessa maisemassa, mika parantaa polytyspalvelun vakautta muuttuvissa olosuhteissa. Kokonaissato per kasvi nousi torjunta-aineiden kayton lisaantyessa. Hyonteispolytyksen ja sadon valista yhteytta heikensi rypsin hyva kompensaatiokyky, jonka ansiosta heikosti polyttyneet kasvit tuottivat enemman kukkia.Yhteenveto ja sovellukset. Viljelykasvin polytysta voi parantaa saatamalla kylvoaikaa siten, etta kasvin kukinta ajoittuu tarkeimpien polyttajien runsaushuippuun. Torjunta-aineiden kayton vahentaminen voi parantaa polytysta mutta laskea samaan aikaan satoa tuholaisten ja rikkakasvien lisaantymisen takia. Polyttajaystavallisten kasvinsuojelukeinojen kehittaminen on tarkeaa korkeiden rypsisatojen ja polytyspalveluiden sailymisen kannalta. Crop pollination can be enhanced by shifting sowing time to better match crop flowering to the peak availability of the most important pollinators. Reduced pesticide use may also enhance pollination services but can lead to the total yield reduction due to pests. This highlights the need for pollinator-friendly pest control methods to maintain turnip rape yields while conserving pollination services.
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(2017)Seasonality causes fluctuations in resource availability, affecting the presence and abundance of animal species. The impacts of these oscillations on wildlife populations can be exacerbated by habitat fragmentation. We assessed differences in bat species abundance between the wet and dry season in a fragmented landscape in the Central Amazon characterized by primary forest fragments embedded in a secondary forest matrix. We also evaluated whether the relative importance of local vegetation structure versus landscape characteristics (composition and configuration) in shaping bat abundance patterns varied between seasons. Our working hypotheses were that abundance responses are species as well as season specific, and that in the wet season, local vegetation structure is a stronger determinant of bat abundance than landscape-scale attributes. Generalized linear mixed-effects models in combination with hierarchical partitioning revealed that relationships between species abundances and local vegetation structure and landscape characteristics were both season specific and scale dependent. Overall, landscape characteristics were more important than local vegetation characteristics, suggesting that landscape structure is likely to play an even more important role in landscapes with higher fragment-matrix contrast. Responses varied between frugivores and animalivores. In the dry season, frugivores responded more to compositional metrics, whereas during the wet season, local and configurational metrics were more important. Animalivores showed similar patterns in both seasons, responding to the same group of metrics in both seasons. Differences in responses likely reflect seasonal differences in the phenology of flowering and fruiting between primary and secondary forests, which affected the foraging behavior and habitat use of bats. Management actions should encompass multiscale approaches to account for the idiosyncratic responses of species to seasonal variation in resource abundance and consequently to local and landscape scale attributes.
