0000000001315654
AUTHOR
Hannu Pietiäinen
showing 8 related works from this author
A possible link between parasite defence and residual reproduction
2007
Life-history theory centres around trade-offs between current and future reproduction, but we have little understanding of how such trade-offs are mediated. We supplementary fed Ural owls (Strix uralensis) during the nestling period and quantified parents' current and future life-history components as well as their physiological health by monitoring haematocrit, leucocyte profile, intra- and extracellular blood parasites. Feeding led to reduced parental effort but did not improve offspring viability, male parasite defence, or parental survival. Intracellular leucocytozoan infection was reduced in fed females which lasted to the following year's reproductive season (carry-over effect), when …
Nonlinear effects of climate on boreal rodent dynamics: mild winters do not negate high-amplitude cycles
2013
Small rodents are key species in many ecosystems. In boreal and subarctic environments, their importance is heightened by pronounced multiannual population cycles. Alarmingly, the previously regular rodent cycles appear to be collapsing simultaneously in many areas. Climate change, particularly decreasing snow quality or quantity in winter, is hypothesized as a causal factor, but the evidence is contradictory. Reliable analysis of population dynamics and the influence of climate thereon necessitate spatially and temporally extensive data. We combined data on vole abundances and climate, collected at 33 locations throughout Finland from 1970 to 2011, to test the hypothesis that warming winte…
Density-dependent vole damage in silviculture and associated economic losses at a nationwide scale
2009
Voles inflict damage to silviculture by debarking or severing tree seedlings. The large-scale impacts of vole damage to silviculture, both in terms of severity and financial losses are, however, poorly known. In autumn 2005, cyclically fluctuating vole populations were at their highest in Finland for over 15 years, which led to extensive damage to silviculture during the winter 2005/06. We carried out a nationwide assessment of the incidence, spatial extent and economic value of damage and its relation to vole abundance in privately owned forests during this winter. Damage data were obtained with a questionnaire addressed to the directors of all Forest Management Associations (FMAs) operati…
Climate change reshuffles northern species within their niches
2022
Climate change is a pervasive threat to biodiversity. While range shifts are a known consequence of climate warming contributing to regional community change, less is known about how species' positions shift within their climatic niches. Furthermore, whether the relative importance of different climatic variables prompting such shifts varies with changing climate remains unclear. Here we analysed four decades of data for 1,478 species of birds, mammals, butterflies, moths, plants and phytoplankton along a 1,200 km high latitudinal gradient. The relative importance of climatic drivers varied non-uniformly with progressing climate change. While species turnover among decades was limited, the …
Parental allocation of additional food to own health and offspring growth in a variable environment
2009
Life-history theory predicts increased investment in current reproduction when future reproduction is uncertain and a more balanced investment in current and future reproduction when prospects for both are good. The outcome of the balance in parental allocation depends on which life-history component maximizes the fitness benefits. In our study sys- tem, a 3-year vole cycle generates good prospects of current and future reproduction for Ural owls (Strix uralensis Pallas, 1771) in increase vole phases and uncertain prospects in decrease vole phases. We supplementary-fed Ural owls during the nestling period in 2002 (an increase phase) and 2003 (a decrease phase), and measured offspring growth…
Maternal effects on offspring Igs and egg size in relation to natural and experimentally improved food supply
2008
1. Maternal effects have been suggested to function as a mechanism for transgenerational plasticity, in which the environment experienced by the mother is translated into the phenotype of the offspring. In birds and other oviparous vertebrates where early development is within the egg, mothers may be able to improve the viability prospects of their offspring at hatching by priming eggs with immunological and nutritional components. 2. We studied how resource availability affects maternal investment in offspring by feeding Ural owl (Strix uralensis, Pall.) females prior to egg-laying in 3 years of dramatically different natural food conditions. 3. Supplementary feeding prior to laying increa…
Predator–vole interactions in northern Europe: the role of small mustelids revised
2014
The cyclic population dynamics of vole and predator communities is a key phenomenon in northern ecosystems, and it appears to be influenced by climate change. Reports of collapsing rodent cycles have attributed the changes to warmer winters, which weaken the interaction between voles and their specialist subnivean predators. Using population data collected throughout Finland during 1986–2011, we analyse the spatio-temporal variation in the interactions between populations of voles and specialist, generalist and avian predators, and investigate by simulations the roles of the different predators in the vole cycle. We test the hypothesis that vole population cyclicity is dependent on predator…
Data from: Predator–vole interactions in northern Europe: the role of small mustelids revised
2014
The cyclic population dynamics of vole and predator communities is a key phenomenon in northern ecosystems, and it appears to be influenced by climate change. Reports of collapsing rodent cycles have attributed the changes to warmer winters, which weaken the interaction between voles and their specialist subnivean predators. Using population data collected throughout Finland during 1986–2011, we analyse the spatio-temporal variation in the interactions between populations of voles and specialist, generalist and avian predators, and investigate by simulations the roles of the different predators in the vole cycle. We test the hypothesis that vole population cyclicity is dependent on predator…