121 research outputs found
Effects of forest fragmentation on reproductive success of birds in boreal forests
No full textThe breeding success was studied experimentally using artificial bird nests. The pied flycatcher (Ficedula hypoleuca Pal.) was used as a study object when the effects of patch size, edges and vegetation characteristics on breeding success and distribution of individuals were examined. Only a minor influence of stand size and forest edge on nest predation was found. High edge-related nest predation existed only in the agricultural landscape where it was mainly caused by avian predators. In the forest landscape, nest predation concentrated to large stands as a function of an increased area of clear-cuts in the surrounding matrix. This was likely due to the penetration of rodent-eating mammalian predators to large stands to search alternative prey when vole populations crashed in the surrounding clear-cuts. The relationship between the nest predation rate and vegetation characteristics surroundings of a nest site was mainly associated with the visibility of nests. Sharp-designed man-made edges did not differ in nest predation risk from more feathered natural edges. At the macrohabitat level, pied flycatchers preferred large and medium-sized stands and avoided settling in small stands, which were mainly occupied by unpaired males. Males preferred edges of forest stands but avoided nest boxes situated right at the edge. The avoidance of small stands was possibly due to high costs of food search and the lower amount of food available in small stands. The costs of food search may also be essential when breeding in the extreme edge zone, since in these sites the suboptimal shape of the foraging area may increase the parents' flying distances in feeding the nestlings. At microhabitat level, adult pied flycatchers males inhabited territories with high numbers of deciduous trees while yearling males territories with high numbers of pines. The reproductive output was better in territories of adult males than in territories of yearling males. This age-related unequal distribution of males in relation to habitat quality was likely due to male-male contest over territories in which adult males dominate over yearlings forcing them to habitats of lower quality.unknown accessibilityei tietoa saavutettavuudest
Metsärajan muutokset Lapissa 1983-2009
No full textTutkimusselosteSeloste artikkelista: Franke A.K., Aatsinki P., Hallikainen V., Huhta E., Hyppönen M., Juntunen V., Mikkola, K., Neuvonen S., Rautio, P. (2015). Quantifying changes of the coniferous forest line in Finnish Lapland during 1983–2009. Silva Fennica vol. 49 no. 5 article id 1408. http://dx.doi.org/10.14214/sf.1408201
Island selection on mammalian life-histories: genetic differentiation in offspring size
No full textBACKGROUND:
Since Darwin's pioneering work, evolutionary changes in isolated island populations of vertebrates have continued to provide the strongest evidence for the theory of natural selection. Besides macro-evolutionary changes, micro-evolutionary changes and the relative importance of natural selection vs. genetic drift are under intense investigation. Our study focuses on the genetic differentiation in morphological and life-history traits in insular populations of a small mammal the bank vole Myodes glareolus.
RESULTS:
Our results do not support the earlier findings for larger adult size or lower reproductive effort in insular populations of small mammals. However, the individuals living on islands produced larger offspring than individuals living on the mainland. Genetic differentiation in offspring size was further confirmed by the analyses of quantitative genetics in lab. In insular populations, genetic differentiation in offspring size simultaneously decreases the additive genetic variation (VA) for that trait. Furthermore, our analyses of differentiation in neutral marker loci (Fst) indicate that VA is less than expected on the basis of genetic drift alone, and thus, a lower VA in insular populations could be caused by natural selection.
CONCLUSION:
We believe that different selection pressures (e.g. higher intraspecific competition) in an insular environment might favour larger offspring size in small mammals. Island selection for larger offspring could be the preliminary mechanism in a process which could eventually lead to a smaller litter size and lower reproductive effort frequently found in insular vertebrates.peerReviewe
Metsätalouden vaikutukset Neidonkenkään : Seurantatutkimus
No full textTutkimuksessa selvitettiin metsärakenteen ja sen muutosten vaikutuksia uhanalaisen EU-direktiivikasvilajin neidonkengän (Calypso bulbosa) esiintymiseen ja lisääntymiseen. Erityisesti tarkasteltiin sitä, minkälaista metsänkäsittelyä neidonkenkä sietää ja kykeneekö kerran hävinnyt kasvupaikka palautumaan, jos paikka uudistetaan metsätalousmenetelmin. Tavoitteena oli myös kehittää menetelmiä lajin seurantaan ja suojeluun. Työtä varten perustettiin noin 50 tutkimusruutua lounais-Lappiin sekä harvennus- ja poimintahakkuukoealat Keminmaahan ja Tervolaan.
Neidonkengistä kukki vuosittain keskimäärin alle puolet. Kukkineista pölyttyi keskimäärin noin kolmannes. Kukinnan ja pölyttymisen onnistuminen näyttää vaihtelevan voimakkaasti eri vuosina ilmeisesti luontaisista syistä. Pienaukkojen lähellä kasveja esiintyi enemmän kuin sulkeutuneissa paikoissa. Ilmeisesti pienaukkojen tuoma valoisuus edisti kasvien esiintymistä niiden läheisyydessä. Isojen aukkojen reunoilla kasvia oli kuitenkin vähemmän kuin metsän sisäosissa. Kukkineiden ja pölyttyneiden kasvien määrät eivät kuitenkaan eronneet reunoissa metsän sisäosista. Miltään harvennushakkuupaikalta neidonkenkä ei ole 10 vuoden seurannan jälkeen hävinnyt. Kukkimisprosentti, kukkien pölyttymisprosentti sekä lisääntymismenestystä kuvaava pölyttymisprosentti per kaikki kasvit vaihtelivat vuosittain samansuuntaisesti koe ja kontrolliruuduissa. Käsittelyn intensiteetillä ei myöskään havaittu olevan vaikutusta neidonkengän säilymiseen ja lisääntymiseen, sillä ne vaihtelivat vuosittain myös aika samalla tavalla eri käsittelyissä. Tarkastelujakso on kuitenkin vielä liian lyhyt todellisten pitkäaikaisvaikutusten arviointiin.202
The impact of tourist destinations on wildlife in northern Finland
No full textIncreased tourism impact, recreational activities and structures in natural areas can affect wildlife by increasing urbanization, landscape fragmentation and disturbance. I examined the potential effects of tourist destinations on four forest grouse (Tetraoninae) and five mammalian species in northern Finland. I analyzed density data obtained from wildlife counts carried out by hunters around ten tourist destinations. The densities of mountain hare and mustelid species were negatively correlated with the distance to a tourist destination. The densities of adult grouse, juvenile grouse, mountain hare, and mustelids were positively correlated with the area of mixed forests surrounding the destinations. The densities of adult and juvenile grouse were positively correlated, while the densities of pine marten and mustelids were negatively correlated with the area of agricultural land surrounding the destinations. The densities of the studied wildlife species varied among destinations and years. It seems that current recreational activities have not caused significant changes in the occurrence and abundance of wildlife species in the surroundings of the tourist destinations studied. Location of a destination, predator densities, and landscape structure around the destination had the most impact on the density of wildlife species.202
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