12 research outputs found
Mallinnuksen käyttö arvioitaessa ilmastonmuutoksen vaikutusta havu- ja lehtinunnan levinneisyyteen
No full textTutkimusselosteSeloste artikkelista: Vanhanen, H., Veteli, T.O., Päivinen, S., Kellomäki, S. & Niemelä, P. 2007. Climate change and range shifts in two insect defoliators: gypsy moth and nun moth – a model study. Silva Fennica 41(4): 621–638
Ilmastonmuutoksen vaikutukset metsätuhoihin ja -tauteihin boraalisen vyöhykkeen metsissä.
No full textMicroclimate and tree community linked to differences in lepidopteran larval communities between forest fragments and continuous forest
No full textThe impact of cutting branches on lepidopteran larval community composition and herbivory
No full textFew immigrant phytophagous insects on woody plants in Europe: legacy of the European crucible?
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A cross-continental test of the Enemy Release Hypothesis: leaf herbivory on Acer platanoides (L.) is three times lower in North America than in its native Europe
No full textAcer platanoides (Norway maple) is a widespread native tree species in Europe. It has been introduced to North America where it has often established dense stands in both secondary woodlands and relatively undisturbed mature woodlands. In Europe A. platanoides is also extending its original range, but generally seems to exist at much lower densities. One explanation for the 'aggressiveness' of invasive plants such as A. platanoides is that they have left behind pests and diseases which limit their population densities in their native lands (the enemy release hypothesis or ERH). To assess the ERH for Norway maple, a large network of collaborators assessed leaf herbivory rates in populations throughout Europe and North America. We found significantly lower total leaf herbivory (1.6% +/- A 0.19, n = 21 vs. 7.4% +/- A 1.94, n = 34) and lower fungal damage (1.0% +/- A 0.35, n = 13 vs. 3.7% +/- A 0.85, n = 34) in North America than in Europe over a 2 year period, which is consistent with the predictions of the Enemy Release Hypothesis. Across years, the average total leaf herbivory was significantly correlated with average annual temperature of the site (P 0.05). Furthermore, only populations in Europe showed very high levels of herbivory (e.g., nine sites had total leaf herbivory ranging from 10.0 to 51.2% in at least 1 year) or leaf fungal damage (only one site in North America showed high levels of fungal damage in 1 year), suggesting the possibility of more frequent episodic outbreaks in the native range. Leaf herbivory and fungal damage are only two aspects of consumer pressure and we do not know whether the differences reported here are enough to actually elicit release from top-down population control, but such large scale biogeographic differences in herbivory contribute towards understanding exotic invasions.VEGA [2/5152/25]; Sponsored Research Office of The University of Montan
Latitudinal and altitudinal pattern in species richness and mortality factors of the galling sawflies on willows in Japan
No full textSpecies richness of willow species and galling sawflies living on them were examined in latitudinal and altitudinal gradients in six Japanese river systems from Hokkaido to southern Honshu. Mortality factors of gallers including plant based mortality, parasitoids and inquilines during larval development were studied by dissecting sampled galls under a microscope. The association between environmental factors, mortality factors and local diversity of galling sawflies and their willow hosts were studied. Species richness of sawfly gallers and their host plants decreased towards the south. Species richness of gallers was lower in the delta area at lower altitudes than at higher altitudes. Different mortality factors, plant based mortality, parasitoids or inquilines, showed no significant trends with latitude or altitude. Although some parasitoids showed a weak correlation with latitude and altitude, but overall survival of larvae was not correlated with latitude or altitude. Among sawfly gall types, Pontania proxima-type was distinct by having high plant-based mortality. The observed pattern of increasing diversity with increasing latitude is opposite to that in many other animals and plants. This pattern is unlikely explained by larval survival different mortality factors since they showed no difference in latitudinal or altitudinal gradient. A possible explanation of the pattern may be the decreasing host plant richness with other host related factors, like increased habitat fragmentation and decreased abundance of host plants towards the south. In addition, leaf flush of host plants and egg laying of galling sawflies might be better synchronized in north with high seasonal but predictable resource availability. I will also present future direction for biodiversity studies.Session 2.1: Biodiversity and Environmental Protection in the Nort
Elevational and latitudinal variation in species richness of sawfly gallers and willows in Japan
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