Paavo Yli-Vakkuri in memoriam

Non peer reviewe

The relationship of abscisic acid concentration in Douglas-fir needles to seedling vigor

A quantitative and predictive measure of seedling vigor during the regeneration chain would be of utmost help for forest regeneration work. This was the impetus to study the possibility of using abscisic acid (ABA) concentration of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) needles as an indicative measure of seedling vigor prior to outplanting. The experiment included two lifting times (mid-November, mid-January), two pretreatments (normal dormancy, fall photoperiod), and three cold storage treatments (dark, light, and bareroot). Needle samples were taken four times during the experiment: 1) after 48 hours in the cold room, 2) prior to taking seedlings out of the cold room after 25 days of storage, 3) 48 hours in the growing environment, and 4) at the time of bud break. Seedling vigor in relation to treatments was assessed under two growing environments: 1) growth room and 2) cold frame. Seedlings were planted in mid-December and mid-February. The concentration of ABA in the needles was quantified by successive procedures of extracting ABA through poly-N-viriylpyrrolidone (PVP), diethylarninoethyl cellulose (DEAE), and octadecyl silica (C18) columns, preparative purification with high-performance liquid chromatography (HPLC), and final quantitation with gas-liquid chromatography (GLC) using an electron capture detector. Results indicate that time of lifting did not affect survival greatly, but markedly influenced the time of bud break. Storage treatments did not result in statistically significant differences in ABA concentrations, survival or shoot growth. Generally, pretreatment with supplementary light in the fall did not produce different results from the normal dormancy pretreatment. Considerable variability in ABA concentrations amongst treatments was found, an occurrence which probably precluded detection of its relationship to seedling vigor. However, there was a tendency, though not significant, of increasing ABA concentrations from mid-November to mid-January. The failure to detect a relationship between ABA and seedling vigor may have been due to a transitory role of ABA in stress conditions or inability to quantitate ABA in its site of action, stomata. Results of this study, along with those of previous studies, support continuance of research on ABA in physiology of plants and its potential use as an indicator of seedling vigor. However, a new synthesis of the role of ABA in seedling metabolism would be fruitful before undertaking new empirical studies as the whole concept of hormone action is undergoing a evolutionary realignment

Effect of Viewing Video Representation of the Urban Environment and Forest Environment on Mood and Level of Procrastination

A common problem among students is the problem of delaying important work activities, which is conceptualized as procrastination. Since procrastination can cause considerable costs for society, we would like to find a method to effectively alleviate the symptoms of this conditioning. It has been proven in an earlier study that staying in the forest environment increases vitality and reduces anxiety, and the negative state of these features can be associated with the intensification of procrastination symptoms. Therefore, it is likely that watching a forest video may decrease the probability or intensity of procrastination. To measure the impact of the forest environment on the level of procrastination of the subjects, a randomized experiment was carried out, in which the subjects watched in random order (on different days) one of two 15-min videos: one showing a walk in the forest area and one showing a walk in an urban environment (control). We measured the level of so-called ‘fluid procrastination’ including three aspects: ‘lack of energy to do the work’, ‘inability to get to work’ and ’pessimistic attitude to do the work’ with a set of questions the respondents completed before and after the experiment. The results showed that one aspect of fluid procrastination (‘pessimistic attitude to do the work’) can be effectively lowered by watching a video showing the forest environment. In contrast, watching a video of an urban environment increased the procrastination levels for two other aspects of procrastination (‘lack of energy to do the work’, ‘inability to get to work’). We also measured three other parameters before and after the experiment: mood state, restoration and vitality. Watching the video from forest area raised mood and restoration and watching the video from urban area, decreased mood, vitality and restoration. The study suggests that watching a video showing forest landscapes could be used as an effective remedy for problems related to procrastination among students

Effect of Viewing Video Representation of the Urban Environment and Forest Environment on Mood and Level of Procrastination

A common problem among students is the problem of delaying important work activities, which is conceptualized as procrastination. Since procrastination can cause considerable costs for society, we would like to find a method to effectively alleviate the symptoms of this conditioning. It has been proven in an earlier study that staying in the forest environment increases vitality and reduces anxiety, and the negative state of these features can be associated with the intensification of procrastination symptoms. Therefore, it is likely that watching a forest video may decrease the probability or intensity of procrastination. To measure the impact of the forest environment on the level of procrastination of the subjects, a randomized experiment was carried out, in which the subjects watched in random order (on different days) one of two 15-min videos: one showing a walk in the forest area and one showing a walk in an urban environment (control). We measured the level of so-called ‘fluid procrastination’ including three aspects: ‘lack of energy to do the work’, ‘inability to get to work’ and ’pessimistic attitude to do the work’ with a set of questions the respondents completed before and after the experiment. The results showed that one aspect of fluid procrastination (‘pessimistic attitude to do the work’) can be effectively lowered by watching a video showing the forest environment. In contrast, watching a video of an urban environment increased the procrastination levels for two other aspects of procrastination (‘lack of energy to do the work’, ‘inability to get to work’). We also measured three other parameters before and after the experiment: mood state, restoration and vitality. Watching the video from forest area raised mood and restoration and watching the video from urban area, decreased mood, vitality and restoration. The study suggests that watching a video showing forest landscapes could be used as an effective remedy for problems related to procrastination among students

Manipulating overstory density and mineral soil exposure for optimal natural regeneration of Scots pine

In northern boreal region the growth of forests is slow, and yield and profit are low, which is why low refor-estation costs are important for profitable forestry. If natural regeneration is successful, expensive artificial forest regeneration (planting or direct seeding) can be avoided. In this study, we look at the impact of overstory density and site preparation on natural regeneration and seedling growth of Scots pine. Study stands were established in different parts of Northern Finland and in each stand following treatments: 50, 150 and 250 trees ha-1 or unthinned control, where the stand density was >= 250 trees ha-1, were randomly allocated to experimental plots. In addition, site preparation (disc trenching, 4000-5000 m ha-1) was carried out on two experimental plots in which tree density was either 50 or 150 trees ha-1. In the experimental stands seedling number, age and growth were monitored for 11 years. Monitoring revealed that the number of seedlings increased with decreasing tree density. Average seedling height growth was very low or even non-existent in the unthinned control and in the densest (250 trees ha-1) treatment, but increased when the density of trees decreased. The highest seedling number and the highest growth were achieved when the tree density was 50 trees ha-1 and the soil was prepared to expose mineral soil. Achieving e.g. 2000 seedlings ha-1, would need about 40% exposition of mineral soil. The required low tree density implies that not only seed supply from seed trees and site preparation is important for regeneration success in northern boreal Scots pine forests but also the reduction of competition by mature trees

What are the effects of even-aged and uneven-aged forest management on boreal forest biodiversity in Fennoscandia and European Russia? A systematic review protocol

Biodiversity is vital for human well-being, but is threatened by human actions world-wide. In the boreal zone, harvesting and management of forests on an industrial scale is the most important factor driving habitat change and degradation. Over time different forest management regimes have been implemented but their impact on biodiversity at different spatial and temporal scales has not been systematically reviewed although non-systematic reviews on the topic exist. The aim of this article is to describe a protocol for a systematic review to synthesise and compare the impacts of two different forest management systems on biodiversity at different spatial and temporal scales. The topic for the systematic review arose from the discussions with the Finnish forestry sector and was further defined in a stakeholder workshop. Research questions addressed by the systematic review protocol are: (1) What are the stand-level effects of even-aged and uneven-aged forest management on boreal forest biodiversity in Fennoscandia and European Russia? (2) What is the effect of these same forest management systems on biodiversity at landscape level?Peer reviewe

What are the effects of even-aged and uneven-aged forest management on boreal forest biodiversity in Fennoscandia and European Russia? A systematic review

Background: Forest harvesting changes forest habitat and impacts forest dependent species. Uneven-aged management is often considered better for biodiversity than even-aged management, but there is an ongoing discourse over the benefits and disadvantages of different silvicultural systems. This systematic review contributes to the public discussion and provides evidence for policy making by synthesising current evidence on impacts of even-aged and uneven-aged forest management on biodiversity in boreal forests of Fennoscandia and European Russia. In this review even-aged and uneven-aged forest management are compared directly to each other as well as to natural forest to provide a broad basis for public discussion. Methods: Both peer-reviewed and grey literature were searched in bibliographical databases, organizational webpages and internet search engines in English, Finnish, Swedish and Russian. Articles were screened for relevance by their title/abstract and again by full text. The inclusion of studies was assessed against pre-defined criteria published in an a priori protocol. A narrative synthesis and meta-analysis were conducted to describe the evidence base and to compare species richness and abundance between differently managed forests. The influence of habitat specialism, taxon, years since harvesting, deadwood availability and harvesting intensity on species richness and abundance were also tested. Review findings: Searching identified 43,621 articles of which 137 articles with 854 studies had independent data and were included in the narrative synthesis. Of those, 547 studies were included in the meta-analysis. The most studied taxa were arthropods, vascular plants, bryophytes, fungi, and lichens. Results showed that forests with less disturbance (uneven-aged and mature even-aged) host more forest dependent species than young even-aged forests ( 80 years old). Uneven-aged forest had similar number of species and individuals than natural forest whereas even-aged forest had less species than natural forest. Open habitat species and their individuals were more numerous in young even-aged forests and forests undergone retention harvest. Effect sizes found were mostly large indicating strong and uniform impact of forest management based on species' habitat preferences. In addition to habitat specialism, years since harvest explained some of the differences found in species richness and abundance due to increase of open habitat species in the early successional stages and forest dependent species in late successional stages. Taxon had limited explanatory power. Conclusions: Habitat preferences determine species' response to different harvesting methods and the magnitude of effect is large. Less disturbance from harvesting is better for forest dependent species whereas opposite is true for open habitat species. Uneven-aged and mature even-aged forests (> 80 years old) are important to maintain biodiversity in boreal forests. However, the results also highlight that natural forests are needed to ensure the future of forest dependent species in Fennoscandia and European Russia. Given that a broader set of biodiversity aspects are to be protected, best overall biodiversity impacts for a variety of species at landscape level can be achieved by ensuring that there is a mosaic of different forests within landscapes.Peer reviewe

Are small protected habitat patches within boreal production forests effective in conserving species richness, abundance and community composition? A systematic review

Background: In boreal zone forest management is changing and degrading forest habitats, which has caused declines in biodiversity. To mitigate these harmful effects in production forests, small-scale habitats with high biodiversity values have been protected within them. These habitats include woodland key habitats, and other small habitat patches protected by voluntary conservation actions. In this systematic review we synthesize the evidence on the value of small protected habitat patches (SPHP) within production forest landscapes for biodiversity. Review question: Are small protected habitat patches within boreal production forests effective in conserving species richness, abundance, and community composition? Methods: Both peer-reviewed and grey literature were searched from bibliographical databases, organizational websites and internet search engines in English, Finnish, Swedish and Russian. Articles were screened at two stages (title/abstract and full text) and the validity of the included studies were assessed. Screening and validity assessment were based on predetermined criteria. After data extraction, narrative and quantitative syntheses were conducted. Influences of effect modifiers were tested, and sensitivity analyses were conducted. Review findings: During the searches 19,458 articles were found. After duplicate removal and title/abstract screening 336 articles remained. During full text screening 41 articles were included and 35 of them (174 studies) were included in narrative synthesis. 28 articles with 127 studies had suitable data for meta-analysis. SPHPs had significantly higher species richness compared to production forests. When compared to natural forests, there was no significant difference. Forest management in areas surrounding SPHPs did not have impact on species richness of these patches. Individual abundance was significantly higher in SPHPs compared to natural or production forests. There was significantly more dead wood in SPHPs compared to production forests, but when compared to natural forests there was no significant difference. Community composition was different between SPHPs and both production and natural forests. Conclusions: The findings of this review show that small protected patches within production forests are important part of biodiversity conservation. They cannot substitute larger protected areas but supplement the protected area network. However, there were gaps both in geographical distribution of the studies as well as in the selection of target species of the studies. Therefore, generalization of the results must be done carefully.Peer reviewe

Effects of overstory tree density, site preparation, and ground vegetation on natural Scots pine seedling emergence and survival in northern boreal pine forests

Natural regeneration is a commonly used forest regeneration method in northern Finland. It is not known, however, what would be the optimal overstory density and ground vegetation composition for seedling emergence and survival, and if site preparation is needed to accompany overstory density manipulation. We studied the effects of overstory density (unthinned control and thinning to 50,150, and 250 trees.ha(-1)) and ground vegetation removal (mechanical site preparation with disc trenching) on the number of naturally germinated pine seedlings and survival of individual seedlings over a period of 8 to 11 years. Bare mineral soil was a superior seedbed compared to intact vegetation cover, even though the mortality rate was high on mineral soil. Greater cover of lingonberry, crowberry, and slash had a negative effect on seedling number. Seedling mortality was initially high (60% died during the first 2 years) but decreased throughout the first 5 years. The survival rate of seedlings located in the mineral soil of the upper part of the disc trencher track was twice as high as that of seedlings located in the lower part of the track. High coverage of hair mosses (Polytrichum spp.) was associated with poorer seedling survival. An overstory density of 50-150 trees.ha(-1) with site preparation seems to be an efficient treatment to promote regeneration under these circumstances.Peer reviewe