Greater Helsinki Area Research Articles

STEAM-Learning to Mars: Students’ Ideas of Space Research

Multidisciplinarity and the enrichment of science and mathematics education toward the so-called STEAM-approach where the A stands for art, has raised a lot of academic interest in the past decade. In this study, 5th and 6th graders from the greater Helsinki area (N = 390) participated in a several months long, Mars-colonization themed STEAM-learning intervention. Testing the students’ science knowledge using pre- and post-tests, their learning outcomes were compared to those of 5th and 6th graders from a control school (N = 119), who during the same period studied STEM-subjects in a more traditional manner. The main factors that were taken into account during the comparisons were gender and academic achievement level. Based on only whether there was any improvement between the pre- and post-test scores, girls were found to have benefitted from the Mars-module more than boys did. While also considering the magnitude of the said improvement, no significant difference in the effectiveness of the learning module was found between genders. The group of academically highest-achieving students improved their test scores the most after participating in the STEAM-learning module. This is an important, somewhat surprising finding, as often informal, outside of school learning has been found to benefit especially students with lower grade point averages.

Laboratory-based surveillance of COVID-19 in the Greater Helsinki area, Finland, February–June 2020

ObjectivesThe aim was to characterise age- and sex-specific severe acute respiratory syndrome coronavirus disease-2 (SARS-CoV-2) RT-PCR sampling frequency and positivity rate in Greater Helsinki area in Finland during February–June 2020. We also describe the laboratory capacity building for these diagnostics. MethodsLaboratory registry data for altogether 80,791 specimens from 70,517 individuals was analysed. The data included the date of sampling, sex, age and the SARS-CoV-2 RT-PCR test result on specimens collected between 1 February and 15 June 2020. ResultsAltogether, 4057/80,791 (5.0%) of the specimens were positive and 3915/70,517 (5.6%) of the individuals were found positive. In all, 37% of specimens were from male and 67% from female subjects. While the number of positive cases was similar in male and female subjects, the positivity rate was significantly higher in male subjects: 7.5% of male and 4.4% of female subjects tested positive. The highest incidence/100,000 was observed in those aged ≥80 years. The proportion of young adults in positive cases increased in late May 2020. Large dips in testing frequency were observed during every weekend and also during public holidays. ConclusionsOur data suggest that men pursue SARS-CoV-2 testing less frequently than women. Consequently, a subset of coronavirus disease-2019 infections in men may have gone undetected. People sought testing less frequently on weekends and public holidays, and this may also lead to missing of positive cases. The proportion of young adults in positive cases increased towards the end of the study period, which may suggest their returning back to social behaviour with an increased risk of infection.

Weekend effect on mortality by medical specialty in six secondary hospitals in the Helsinki metropolitan area over a 14-year period

BackgroundThe weekend effect is the phenomenon of a patient’s day of admission affecting their risk for mortality. Our study reviews the situation at six secondary hospitals in the greater Helsinki area over a 14-year period by specialty, in order to examine the effect of centralization of services on the weekend effect.MethodsOf the 28,591,840 patient visits from the years 2000–2013 in our hospital district, we extracted in-patients treated only in secondary hospitals who died during their hospital stay or within 30 days of discharge. We categorized patients based on the type of each admission, namely elective versus emergency, and according to the specialty of their clinical service provider and main diagnosis.ResultsA total of 456,676 in-patients (292,399 emergency in-patients) were included in the study, with 17,231 deaths in-hospital or within 30 days of discharge. A statistically significant weekend effect was observed for in-hospital and 30-day post-discharge mortality among emergency patients for 1 of 7 specialties. For elective patients, a statistically significant weekend effect was visible in in-hospital mortality for 4 of 8 specialties and in 30-day post-discharge mortality for 3 of 8 specialties. Surgery, internal medicine, and gynecology and obstetrics were most susceptible to this phenomenon.ConclusionsA weekend effect was present for the majority of specialties for elective patients, indicating a need for guidelines for these admissions. More disease-specific research is necessary to find the diagnoses, which suffer most from the weekend effect and adjust staffing accordingly.

Three-decade neurological and neurocognitive follow-up of HIV-1-infected patients on best-available antiretroviral therapy in Finland

ObjectivesIs it possible to live without neurocognitive or neurological symptoms after being infected with HIV for a very long time? These study patients with decades-long HIV infection in Finland were...

Abstract W P295: Admission Is Delayed in Patients with Predominantly Visual Symptoms of Ischemic Occipital Stroke

Introduction: Stroke patients with predominantly visual symptoms due to posterior circulation ischemia rarely receive thrombolytic treatment despite the often debilitating nature of their homonymous visual field deficits. In addition to stroke physicians’ judgment of risks and benefits, perhaps influenced also by low scores on the National Institutes of Health Stroke Scale, lack of thrombolytic treatment may be caused by delayed admission to a stroke center. Hypothesis: We hypothesized that patients with occipital infarcts presenting with predominantly visual field symptoms would show less direct routes and longer onset-to-admission delays to a stroke center compared to the general stroke population, of which approximately half are admitted within 4h of symptom onset. Methods: All patients with visual field deficits as their primary symptom of occipital infarction treated at the Helsinki University Central Hospital between 2010 and 2013 were retrospectively identified from all cases of ischemic stroke by careful review of medical records and radiological data. All patients with acute stroke within the Greater Helsinki area (catchment area of 1.5 million) are brought to our emergency room (ER). Data were gathered on admission route and length of delay from symptom onset to admission. Results: Of the 179 occipital ischemic stroke patients with hemianopia as their main symptom or sign, 32 (18%) were admitted within 4h of symptom onset and a further 64 (36%) within 4-24h. Only 17 patients (9.5%) arrived as pre-notified thrombolysis candidates. 10 patients (5.6%) received thrombolysis, but half of them were only recognized as thrombolysis candidates after ER admission. Of all patients, 35 (20%) arrived directly at our ER, whereas 45 (25%) had visited two or more points of care or had been initially discharged, with a significant proportion of all patients, 30%, having visited an ophthalmologist prior to admission. Conclusions: Recognizing ischemic stroke presenting with visual field symptoms is challenging. Complexity of patient routes and long admission delays likely contribute to the low rates of thrombolytic therapy in this patient group.

Modelling travel time in urban networks: comparable measures for private car and public transport

Analysing the accessibility disparity between different travel modes is recognised as an efficient way to assess the environmental and social sustainability of transport and land use arrangements. Travel times by different travel modes form an essential part of such an analysis. This paper aims to assess the comparability of different methods for calculating travel time by different travel modes. First, we briefly review the methods used in previous studies and identify different typical approaches, which we then compare. We use three computational models respectively for car and public transport (PT), implemented in our case study area, the capital region of Finland. In the car models, (1) the simple model ignores congestion and parking in travel time calculation; (2) the intermediate car model accounts for congestion but ignores parking; and (3) the more advanced car model takes into account all parts of the journey, including congestion and parking. For PT, (1) the simple model accounts for transit routes but ignores schedules; (2) the intermediate model incorporates schedule data in a simplistic way; and (3) the more advanced model adopts a door-to-door approach where true schedules (incl. congestion) and realistic route combinations are accounted for. Our results show that absolute differences in car and PT travel times are notable in the Greater Helsinki area, no matter which models are used for comparison. Modal travel time disparity appears smallest in the city centre area. We conclude that using conceptually corresponding models for car and PT travel time calculations is the key to achieving a reliable analysis of modal accessibility disparity. A door-to-door approach in travel time calculations (adopted in the most advanced models) also makes the results truly comparable in absolute terms. Finally, the more advanced the applied methods are, the more data hungry the analysis is. Here, recent developments in open data policies among urban transport data producers become very helpful.

Modelling the potential effect of shared bicycles on public transport travel times in Greater Helsinki: An open data approach

In many European cities, support for public transport and cycling in daily mobility is considered an efficient means to reduce air pollution, traffic jams, and carbon emissions. Shared bicycle systems have turned out effective in increasing cycling in many urban areas, particularly when combined with public transportation. In this study, we make an effort to model a hypothetical shared bike system and quantify its spatial effect on public transport travel times. The study area is one of the fastest growing urban agglomerations in Europe, the Greater Helsinki area in Finland. We model the travel times between the population and 16 important destinations in the city centre of Helsinki by public transportation and by public transportation extended with shared bikes. We use open route and timetable databases and tools developed in-house to perform extensive data mining through application programming interfaces (APIs). We show 1) that open transport information interfaces can provide a new effective means to evaluate multimodal accessibility patterns in urban areas and 2) that the launch of a bicycle sharing system could reduce public transportation travel times in the study area on average by more than 10%, meaning some 6 min per each individual trip. We conclude that bicycle sharing systems complementing the traditional public transport system could potentially increase the competitiveness and attractiveness of sustainable modes of urban transport and thus help cities to promote sustainable daily mobility. Finally, we emphasize that the availability of open data sources on urban transport information – such as the public transport data in our case – is vital for analysis of multimodal urban mobility patterns.

Twelve-year trend in treatment seeking for buprenorphine abuse in Finland

BackgroundBuprenorphine abuse is becoming increasingly common worldwide. However, large-scale long-term studies of buprenorphine abuse are lacking. The objective of this study was to examine the trend in characteristics of clients seeking treatment for buprenorphine abuse and compare them to those seeking treatment for heroin and amphetamine abuse. MethodsA 12-year descriptive study was conducted at the Helsinki Deaconess Institute (HDI), a public utility foundation responsible for providing treatment for substance abuse in the greater Helsinki area. All clients seeking treatment between 31 January 1997 and 31 August 2008 received a structured clinical interview concerning demographic characteristics and abuse patterns. Characteristics of clients who reported that their primary drug of abuse was buprenorphine (n=780) were compared to those whose primary drug of abuse was either heroin (n=598) or amphetamine (n=1249). ResultsThe annual proportion of buprenorphine clients increased from 3.0% in 1998 to 38.4% in 2008. Daily abuse (73.8%) and intravenous administration (80.6%) were common among buprenorphine clients. Concurrent abuse of prescription medications (p<0.001), stimulants (p=0.001) and alcohol (p<0.001) increased from 1997 to 2008. Treatment seeking for heroin abuse declined to approximately 1% of clients annually after 2002. Buprenorphine clients were more likely to be daily users of their primary drug (p<0.001), abuse prescription medications (p<0.001) and administer drugs intravenously (p=0.001 from 1997 to 2001) compared to heroin and amphetamine clients. ConclusionsOur results highlight the increasing abuse of buprenorphine in Finland. Buprenorphine clients had risky abuse patterns in terms of daily use and intravenous administration. Concurrent substance abuse increased during the study period.

Comparison of Satellite Cloud Masks with Ceilometer Sky Conditions in Southern Finland

AbstractThe cloud mask is an essential product derived from satellite data. Whereas cloud analysis applications typically make use of information from cloudy pixels, many other applications require cloud-free conditions. For this reason many organizations have their own cloud masks tuned to serve their particular needs. Being a fundamental product, continuous quality monitoring and validation of these cloud masks are vital. This study evaluated the performance of the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Meteorological Products Extraction Facility cloud mask (MPEF), together with the Nowcasting Satellite Application Facility (SAFNWC) cloud masks provided by Météo-France (SAFNWC/MSG) and the Swedish Meteorological and Hydrological Institute (SAFNWC/PPS), in the high-latitude area of greater Helsinki in Finland. The first two used the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument from the geostationary Meteosat-8 satellite, whereas the last used the Advanced Very High Resolution Radiometer (AVHRR) instrument on board the polar-orbiting NOAA satellite series. Ceilometer data from the Helsinki Testbed, an extensive observation network covering the greater Helsinki area in Finland, were used as reference data in the cloud mask comparison. A computational method, called bootstrapping, is introduced to account for the strong temporal and spatial correlation of the ceilometer observations. The method also allows the calculation of the confidence intervals (CI) for the results. This study comprised data from February and August 2006. In general, the SAFNWC/MSG algorithm performed better than MPEF. Differences were found especially in the early morning low cloud detection. The SAFNWC/PPS cloud mask performed very well in August, better than geostationary-based masks, but had problems in February when its performance was worse. The use of the CIs gave the results more depth, and their use should be encouraged.

Carabid beetle assemblages associated with urban golf courses in the greater Helsinki area

Golf is a popular sport, with increasingly large areas of urban and peri-urban land being designated for golf course development. Yet, more than half of the land area of a typical golf course is considered rough and out-of-play areas that can, if managed appropriately, provide habitats for wildlife. Using pitfall traps, 6944 carabid beetles belonging to 72 species were collected from five urban golf courses and three areas designated for golf course development around the city of Helsinki, Finland in 2007. The courses were rich in carabid species and distinct in their species assemblages. Golf courses were dominated by habitat generalists, species capable of flight and medium to large-sized species. The three courses with areas designated for further golf course development showed that the assemblages of beetles associated with these golf courses have retained many elements from the pre-existing habitats. The oldest golf course is characterised by a more evenly distributed and diverse carabid beetle assemblage, probably due to its higher habitat heterogeneity and longer successional development. However, even this golf course is dominated by generalist species, implying that golf courses may not provide suitable habitats for specialists. It is assumed that the high species richness of golf courses is attributed to the high habitat diversity of these environments, ranging from the strongly human-modified to more natural patches, which provide habitats for many generalist and open-habitat species. Golf courses may, however, with the appropriate management of out-of-play areas provide an opportunity for conserving biodiversity.

Ambulatory Blood Pressure in Young Adults with Very Low Birth Weight

We hypothesized that, as compared with a matched control group born at term, young adults with very low birth weight (VLBW <1.5 kg) would have higher 24-hour ambulatory blood pressure. We studied 118 18- to 27-year-old subjects born with VLBW within the greater Helsinki area and 120 term-born control subjects with similar age, sex, and birth hospital. The mean birth weight for VLBW subjects was 1.1 kg (standard deviation [SD], 0.2) and for controls, 3.6 kg (SD, 0.5). Gestational ages were 29.2 (SD, 2.3) and 40.1 (SD, 1.0) weeks. Current education of higher-educated parents served as an indicator of childhood socioeconomic status. Ambulatory blood pressure was measured during a 24-hour period with an oscillometric device (Spacelabs 90207). VLBW subjects had, with sex, age, and body mass index adjustment, a 2.4 mm Hg (95% confidence interval, 0.2 to 4.6) higher 24-hour systolic pressure. We found hypertension in 11 VLBW subjects and in 3 term-born subjects, giving an adjusted odds ratio of 4.0 (1.1 to 14.8). When socioeconomic status was taken into account, results remained unchanged. Higher rates of hypertension and higher 24-hour blood pressure among young adults with VLBW may indicate higher risk for adverse cardiovascular outcomes.

Detection of pregnancies with high risk of fetal macrosomia among women with gestational diabetes mellitus

To compare the frequency of fetal macrosomia and Erb's palsy in two groups of women with gestational diabetes mellitus (GDM) and in healthy controls. Retrospective clinical study of women with GDM. Pregnant women in Greater Helsinki area. Nine hundred and five pregnancies and newborn infants of women with GDM and 805 non-diabetic controls. GDM was diagnosed by a 2-hour oral glucose tolerance test (OGTT) among women with risk factors for GDM. The treatment of GDM was resolved by a 24-hour glucose profile obtained after 2 or 3 abnormal glucose values in the OGTT. Patients with a history of insulin-treated GDM in a previous pregnancy and those with a fasting glucose over 6 mmol/l underwent a 24-h glucose profile directly without a preceding OGTT. Fetal macrosomia, defined as a birth weight (adjusted for sex and gestational age) of >2.0 SD above the mean of a Finnish standard population. Erb's palsy. 385 women (42.5%) were treated with insulin and diet and 520 (57.5%) with diet only. Macrosomia occurred more often in the insulin-treated group (18.2%, p<0.001) compared with the diet-treated group (4.4%) and the controls (2.2%). The rate of Erb's palsy was 2.7% in the insulin-treated group, 2.4% in the diet-treated group, compared with 0.3% in the controls (p<0.001). The 24-hour glucose profile performed after the diagnosis of GDM clearly distinguishes between low-risk (diet-treated) and high-risk (insulin-treated) for fetal macrosomia in GDM pregnancies.

Trampling tolerance of understorey vegetation in different hemiboreal urban forest site types in Finland

The effects of trampling on the understorey vegetation were studied in boreal urban forests of different fertility in the greater Helsinki area, Finland. The three studied forest types in decreasing order of fertility were: 1) herb-rich heath forest, 2) mesic heath forest, and 3) sub-xeric heath forest. We inventoried the cover percentages of understorey vegetation in 40 herb-rich, 75 mesic and 40 sub-xeric biotopes located in 51 urban forests varying in size (0.6–502 ha). Cover percentages were compared to those of untrampled reference areas. In our study, trampling tolerance increased with increasing fertility of the forest type. Wear of understorey vegetation correlated positively with the number of residents (i.e. recreational pressure) around the forest patch. In general, understorey vegetation cover in all three forest types was lower than in the same forest types in untrampled reference areas. Ground layer cover in urban forests was less than half of that in reference areas. Mosses, lichens, and dwarf shrubs, especially Vaccinium vitis-idaea, proved to be sensitive to trampling and consequently decreased in cover. The cover of tree saplings, mainly Sorbus aucuparia, and some resilient herbs increased.

Effects of recreational use and fragmentation on the understorey vegetation and soil microbial communities of urban forests in southern Finland

The impacts of fragmentation and recreational use on the hemiboreal urban forest understorey vegetation and the microbial community of the humus layer (the phospholipid fatty acid (PLFA) pattern, microbial biomass and microbial activity, measured as basal respiration) were examined in the greater Helsinki area, southern Finland. Trampling tolerance of 1) herb-rich OMT, 2) mesic MT, and 3) sub-xeric VT forests (in decreasing order of fertility) was studied by comparing relative understorey vegetation cover (urban/untrampled reference ratio) of the three forest types. The trampling tolerance of forest vegetation increased with the productivity of the site (sub-xeric < mesic < herb-rich). Wear of understorey vegetation correlated positively with the number of residents (i.e., recreational pressure) around the forest patch. An increase of 15000 residents within a radius of 1 km around a forest patch was associated with ca. 30% decrease in the relative understorey vegetation cover. The cover of dwarf shrub Vaccinium myrtillus in particular decreased with increasing levels of wear. The cover of mosses in urban forests was less than half of that in untrampled reference areas. Cover of tree saplings, mainly Sorbus aucuparia, and some resilient herbs was higher than in the reference areas. In small urban forest fragments, broad-leaved trees, grasses and herbs were more abundant and mosses were scarcer than in larger urban forest areas. Thus, due to trampling and edge effects, resilient herb and grass species are replacing sensitive dwarf shrubs, mosses and lichens in urban forests. Differences in the soil microbial community structure were found between paths and untrampled areas and the effects of paths extended more than one meter from the paths. Paths supported approximately 25-30% higher microbial biomass with a transition zone of at least 1 m from the path edge. However, microbial activity per unit of biomass was lower on paths than in untrampled areas. Furthermore, microbial biomass and activity were 30-45% lower at the first 20 m into the forest fragments, due to low moisture content of humus near the edge. The decreased microbial activity detected at forest edges and paths implies decreased litter decomposition rates, and thus, a change in nutrient cycling. Changes in the decomposition and nutrient supply may in turn affect the diversity and function of plant communities in urban forests.

Predicting offender home location in urban burglary series

Residential location of a criminal can be predicted statistically [M. Laukkanen, P. Santtila, Predicting the home location of a serial commercial robber, Forensic Sci. Int. 157 (2006) 71–82]. Examined were: accuracy of the technique for urban burglary series, correlations between way of committing burglary and distance and use of those correlations in enhancing prediction accuracy. Data: 78 residential burglary series from Greater Helsinki area, Finland. Series for which the home location prediction was made was never part of the predicting model. Distances between home and crime-site were short (Mdn 3.88 km; IQR = 1.16–10.10 km). Search area of a perpetrator could be limited to 1.95% (Mdn, IQR = 0.64–18.70%) of the total study area. For series which conformed to Circle Hypothesis (45%), search area was 0.84% (Mdn, IQR = 0.51–2.34%). Correlations between crime features and distance were found to enhance accuracy when features of series hinted short distance: sub-model limited search area to 0.19% (Mdn, IQR = 0.07–0.65%).

Price setting and the reluctance to realize losses in apartment markets

Using data on all real estate transactions in the greater Helsinki area during 1987–2003 (about 80,000 apartment transactions with capital gains available), we find substantial support for loss realization aversion. Further, a disproportionate number of sales occurred exactly at the original purchase price. Reluctance to realize losses is weaker with pricier apartments, seasoned sellers, and apartments that are likely bought for investment purposes. Mortgage down payment requirements are unlikely to fully explain the results. On the whole the results are consistent with loss aversion and mental accounting.

Predicting the residential location of a serial commercial robber

Residential location of a serial offender can potentially be predicted by using models created from home to crime site journeys of solved crimes in the area [N. Levine, Journey-to-crime estimation, retrieved 23 October 2003 from http://www.icpsr.umich.edu/NACJD/crimestat/CrimeStatChapter.9.pdf, last visited 1 February 2005]. Aims of this study were: (1) to examine the accuracy of this technique, (2) to explore relation of modus operandi (m.o.) to the distance the crime was committed from home and (3) to analyse whether the accuracy of prediction is enhanced by taking the m.o. into account. Data consisted of 76 commercial robbery series from the Greater Helsinki area. Accuracy of prediction was tested by using leave-one-out technique: the series which the predicting function was applied to was never part of the function used to predict. The functions allowed limiting the area to be searched to 4.7% (Mdn, IQR = 31.0%) of the study area generally, and to 1.0% (Mdn, IQR = 2.6%) when the suspect's spatial behaviour conformed to the circle hypotheses presented by Canter and Larkin [D. Canter, P. Larkin, The environmental range of serial rapists, J. Environ. Psychol. 13 (1993) 63–69]. Significant correlations between m.o. and the length of the journey-to-crime were found, but this information did not enhance accuracy of prediction. Low percentage of marauder style perpetrators in the data gives support to the possible separation of hypotheses of underlying spatial behaviour in instrumental crimes versus crimes of interpersonal violence or arson. Suggestions for development of investigative tools are presented.

55+ people as internet users

PurposeExplores internet‐related needs and wants of older adults and identifies internet user segments among them.Design/methodology/approachThe internet, primarily designed for the young, has been at the centre of research and business attention for a number of years, whereas so far older age groups have received surprisingly little attention. A survey in the Greater Helsinki area in Finland was undertaken.FindingsThe survey showed that every 55+ respondent was acquainted with the internet and that one‐third of the respondents were non‐users, while the majority were frequent web visitors using and purchasing internet services to an extent fairly similar to younger counterparts. Two segments in line with the life‐stage model, labelled healthy indulging and ailing outgoing internet users, were found and show that there is heterogeneity among this age group.Research limitations/implicationsA limitation common to surveys also concerns this study, namely that the sample was quite small – 127 respondents – and strictly defined. Therefore in future studies it would be justified to expand the number and type of studied 55+ respondents, and also to conduct studies that reveal their real internet behaviour such as observation and participatory studies. Implications for web designers, service providers, and politicians are presented which are based on the respondents' own practical development ideas and suggestions.Originality/valueThe study is valuable because it sheds light on a rapidly increasing market segment on which there currently are very limited empirical findings, in particular outside the USA and concerning internet values and behaviour.

Effect of type of screening laboratory on population-based occurrence of cervical lesions in Finland.

The incidence of cervical cancer decreased in Finland over a 30-year period because of an effective screening program, but in the beginning of the 1990s it began to increase. Reasons for such an increase are variable: changes in sexual habits, shortcomings in attendance for screening and possibly variation in laboratory quality. We evaluated the impact of 3 laboratories in the greater Helsinki area on screening performance and on the incidence of invasive cervical cancer and preinvasive cervical lesions in the target population. We studied time trends, geographic differences in attendance and detection rates from screening and the incidence of invasive cancer in the greater Helsinki area (population about 1 million) during the 1990s, when screening was reorganized from the Cancer Society of Finland laboratory to the municipal one (Helsinki) and to a private laboratory (Espoo), while in Vantaa screening remained with the same Cancer Society laboratory. The attendance rate for screening increased during the study period in all 3 cities. The numbers of cytologically suspected and histologically confirmed precancerous lesions found, including severe lesions, decreased significantly with the change of laboratory in Espoo; but in Helsinki and Vantaa, they increased. The overall incidence of invasive cervical cancer increased in all cities in the age groups screened but mostly in Espoo. The rather rapid changes and variation in trends in the number of screening findings cannot be explained by changes in etiologic factors or attendance. They may be related more to the quality of the laboratory performance and perhaps to the criteria used in cytology and colposcopy. A well-organized auditing system is proposed to maintain high quality in screening.

Anthropogenic effects on understorey vegetation in Myrtillus type urban forests in southern Finland

The growth of urban population in Finland has resulted in increased fragmentation of urban forests and consequently increased recreational pressure on these forests. The effects of fragmentation and trampling on the ground and field layer vegetation were studied in mesic Myrtillus type Norway spruce-dominated urban forest stands of varying size in the greater Helsinki area. The number of residents living in the vicinity of the forest stands was an important factor affecting the understorey vegetation in urban forests. The cover of understorey vegetation in urban forests was remarkably lower than in rural areas, especially the ground layer cover, e.g. cover of Pleurozium schreberi, was significantly lower in urban forests than in the reference areas. Thus, the ground layer proved to be most susceptible to trampling. In the field layer, the cover of dwarf shrubs, especially of Vaccinium myrtillus, was lower in deteriorated than in undeteriorated urban forest stands.