The importance of nesting cavity and tree reuse in the three-toed woodpecker Picoides tridactylus in dynamic forest landscapes

Cavity-nesting birds can save time and energy by reusing old cavities. We studied cavity reuse and its connections to nesting success and timing in the three-toed woodpecker Picoides tridactylus in a 170-km(2) area in southern Finland during 1987-2015. The data include 520 nest trees, 645 nest cavities and 833 nestings in 86 territory sites, including 211 cases of cavity reuse. Twenty-five percent of nestings was in previously used cavities. Twenty-eight percent of cavities and 25% of nest trees were used more than once. Reuse improved nesting success and facilitated early nesting in the year following first nesting. Reuse of nest trees with several cavities was observed in 15% of nest trees, and 62% of reused cavities were in those multi-cavity trees. Cavity reuse and multi-cavity trees were most abundant in long-term territories with stable habitats. In boreal forests, cavity and tree reuse can be an important adaptation allowing efficient nesting during a short breeding season.Peer reviewe

Three-toed Woodpecker cavities in trees : A keystone structural feature in forests shows decadal persistence but only short-term benefit for secondary cavity-breeders

Primary cavity-producers like woodpeckers are often considered as keystone species, because they produce nest sites also for several other cavity-nesting animals and, thus, maintain ecological webs of cavity-breeders. However, the detailed temporal dynamics of cavities and their lifetime occupancy rates and survival are not usually known which makes it difficult to assess the actual significance and full impact of primary cavity breeders. In this study, we monitored cavities in a large forest landscape, covering the full lifetime of cavities. We focused on a mature and old-growth forest specialist cavity-breeder, the Three-toed Woodpecker Picoides tri-dactylus. The data include the annual occupancy history of 655 old cavities of the Three-toed Woodpecker in 86 territories in a 170-km(2) area in southern Finland during 1987-2017. The study area included both managed and natural forest types. The median survival time of a cavity was 10 years, but there were significant differences between forest area types with a range of 7-13 years. The occupancy in all cavities was 21.3%, and the cavities were available for secondary cavity-breeders each year. There was a significant negative correlation between the occupancy and the age of the cavity. The first five years of a cavity were important for the total occupancy, and 86% of occupancies took place before the median age of the cavities. In cavities older than 15 years the occupancy was only 7%. The pattern was similar in all types of forests. Our results show that cavities made by Three toed Woodpeckers have rather long lifespan but also that their active use by other cavity-breeding species is restricted mostly to few years only. The result indicates that new, fresh cavities are needed continuously in a forest landscape, in order to maintain the role that Three-toed Woodpecker has as a keystone species.Peer reviewe

Nest tree characteristics of the old-growth specialist Three-toed Woodpecker Picoides tridactylus

The Three-toed Woodpecker Picoides tridactylus is a mature and old-growth forest specialist but how the species uses trees for nesting in its breeding sites and whether cavity trees are a critical habitat feature is poorly known. We studied the nest tree characteristics of the species in a 170-km(2) area in southern Finland during 1987-2016. The data included 538 nest trees of eight different species and 665 nest cavities in 86 territory areas. Norway spruce Picea abler was the predominant nest tree comprising 71% of all nest trees. Proportionally, deciduous nest trees were more common in moist forests on mineral soils and conifer nest trees more common in spruce swamps. The majority of nest trees (85%) were dead or decaying trees; higher numbers of dead deciduous nest trees were recorded than dead conifer trees. The mean diameter of a nest tree at diameter at breast height (DBH) was 29.4 cm and the mean height of a cavity hole was 5.1 m; size and height were significantly positively correlated. The proportion of deciduous nest trees was significantly higher (45%) in natural forests compared with other areas subjected to variable amounts of forest management, where the respective proportion was only 9-17%. In addition, cavity holes were significantly higher in natural forests than in managed ones. In general, the results highlight the substantial flexibility in nest tree use but also the importance of large dead and decaying trees (including deciduous trees) as nest cavity sites for the species. Spruce swamps can be considered as key nesting habitats in managed forest landscapes.Peer reviewe

Nest tree characteristics of the Lesser Spotted Woodpecker (Dendrocopos minor) in boreal forest landscapes

Tree cavities, and especially cavities made by woodpeckers, are important microhabitats in forest ecosystems. However, the properties of woodpecker nest trees and cavities are poorly known even in boreal areas where most tree cavities are made by woodpeckers. We studied the nest tree characteristics of the Lesser Spotted Woodpecker (Dendrocopos minor) in a 170-km(2) forest-dominated area in southern Finland during 1987-2018. The data included 97 nest trees with 106 nest cavities in five deciduous tree species. During the study period, more than one nest cavity (2-3) was excavated in 7% of all cavity trees. Nests were found in three forest types, but the proportions of nest tree species differed between them. Birch (Betula spp.) was the most common nest tree species with 40% of nests. Nest trees were either dead (79%) or decaying (21%), and the majority (69%) had a broken top. The mean diameter at breast height (DBH) of a nest tree was 24.7 cm and the mean height of a cavity hole was 3.3 m; size and height were significantly positively correlated. The mean ratio of cavity height in relation to the respective nest tree height was 0.49, and did not depend on the nest tree condition. The results highlight the importance of dead and decaying deciduous trees as nest cavity sites for this small woodpecker species. Provision of suitable cavity trees during forest management is important to maintain breeding and cavity building opportunities for the Lesser Spotted Woodpecker in managed forests.Peer reviewe

Puolesta-asiointi sosiaali- ja terveydenhuollossa : Toiminnallinen määrittely

Tämän vanhan painoksen korvaava dokumentti Sähköinen puolesta-asiointi sosiaali- ja terveydenhuollossa – Yleiskuvaus löytyy osoitteesta: https://thl.fi/fi/web/tiedonhallinta-sosiaali-ja-terveysalalla/maaraykset-ja-maarittelyt/maarittelyt-sotelle-yhteisesti</a

Diverse population trajectories among coexisting species of subarctic forest moths

Records of 232 moth species spanning 26 years (total catch of ca. 230,000 specimens), obtained by continuous light‐trapping in Kevo, northernmost subarctic Finland, were used to examine the hypothesis that life‐history traits and taxonomic position contribute to both relative abundance and temporal variability of Lepidoptera. Species with detritophagous or moss‐feeding larvae, species hibernating in the larval stage, and species pupating during the first half of the growing season were over‐represented among 42 species classified as abundant during the entire sampling period. The coefficients of variation in annual catches of species hibernating as eggs averaged 1.7 times higher than those of species hibernating as larvae or pupae. Time‐series analysis demonstrated that periodicity in fluctuations of annual catches is generally independent of life‐history traits and taxonomic affinities of the species. Moreover, closely related species with similar life‐history traits often show different population dynamics, undermining the phylogenetic constraints hypothesis. Species with the shortest (1 year) time lag in the action of negative feedback processes on population growth exhibit the largest magnitude of fluctuations. Our analyses revealed that only a few consistent patterns in the population dynamics of herbivorous moths can be deduced from life‐history characteristics of the species. Moreover, the diversity of population behaviour in one moth assemblage challenges any conventional wisdom suggesting predictable patterns. Our results raise several questions about perceptions and paradigms in insect population dynamics and stress the need for research on detritivorous insect population dynamics, as well as the need for more assemblage‐wide studies using common trapping methods to provide comparative data on related and unrelated species with different life‐history traits.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146872/1/pope0295.pd

Ecological Restoration of the Boreal Forest in Fennoscandia

Mixed-severity disturbances have historically shaped boreal forests, creating a dynamic mosaic landscape. In Fennoscandia, however, intensive even-aged forest management has simplified the forest landscape, threatening biodiversity. To safeguard this biodiversity, we therefore need to restore structural complexity in hitherto managed forests. Knowledge generated from relevant case studies on natural disturbance emulation–based ecological restoration suggests that prescribed burning positively affects many early-successional organisms. Gap cutting benefits some insects and wood fungi but has a limited effect on birds, bryophytes, and vascular plants. Restoration of deciduous forests appears to benefit light- and deciduous tree–associated insect species and some forest birds