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Three types of experiments indicate that the functional organization of the mountain birch may influence the ways in which the tree responds to simulated or natural herbivory. The first experiment showed that herbivory to both short and long shoot leaves affects plant development but, because growth largely proceeds by resources of the previous year, is(More)
The study was carried out to assess the effect of both short-and long-term copper exposure on five cladoceran species differing in body size and habitat, i.e. Daphnia magna, D. pulex, D. galeata, Bosmina longirostris, and Chydorus sphaericus. The species-specific 48 h EC50 values for fed neonates were used to determine the chronic exposure levels (52% and(More)
We studied the effects of environmental factors on the ability to compensate for simulated herbivory in an annual (Urtica urens) and two perennial (U. dioica subspp. dioica and sondenii) nettle species in order to test the compensatory continuum hypothesis. Further, we studied the expression of costs of structural defence in different environmental(More)
Over the past 50 years, human beings have influenced ecosystems more rapidly than at any similar time in human history, drastically altering ecosystem functioning. Along with ecosystem transformation and degradation, a number of studies have addressed the functioning, assessment and management of ecosystems. The concept of ecosystem services has been(More)
We studied the role of plant vascular architecture in the determination of the spatial extent of herbivore induced responses within Betula pendula Roth saplings. The induced responses were measured in bioassays in terms of the relative growth rate of larvae of a geometrid moth, Epirrita autumnata. We hypothesised that the level of induced resistance of a(More)
Several studies have found genetic variation in plant resistance to herbivory. One of the explanations suggested for the observed intermediate levels of resistance are the costs of resistance, i.e., negative genetic correlations between resistance and other fitness components that may constrain the evolution of resistance. We studied the cost of herbivore(More)
We examined the demographic costs of Chaoborus-induced defensive spine structures in Daphnia pulex. Our aim was to assess the role of resource limitation and the interaction effects of limiting food level and antipredator structures on fitness of D. pulex and to pinpoint those life stages that are most sensitive to changes in the defence regime.(More)
We measured the effects ofEriophyes laevis mite galls on the relative growth of short shoot leaf area ofAlnus glutinosa. A portion of leaves was artificially removed from a set of short shoots with both high and low gall density to cause local stress conditions. Nontreated high and low gall density short shoots were used as controls. The results show that(More)
The prominent theme in the debates concerning biodiversity has been the integration of biodiversity into social and economical processes. Integration has meant two different but related things: on one hand, biological phenomena have been contextualized in social and economical processes; on the other hand, biological issues have been incorporated into(More)
The role of nitrogen as a factor controllingphytoplankton biomass was studied in nutrientenrichment incubations in the laboratory using waterfrom pelagic region of two mesotrophic lakes ineastern Finland, Lake Kallavesi (in year 1994) andLake Juurusvesi (in year 1995). We used differentcombinations of phosphorus and nitrogen additions ina total of eight(More)