The written history of plant phenology: shaping primary sources for secondary publications.

Phenological research establishes the science of nature's natural calendar. This research, the monitoring and analysis of seasonal rhythms of plants and animals, is commonly based on citizen science data. Such data may be digitized from primary sources provided by the citizen scientist's original phenological diaries. Secondary data sources are formed by historical publications (for example, yearbooks and climate bulletins). While primary data has the advantage of first-hand notetaking, its digitization may, in practice, be time-consuming. Contrastingly, secondary data can contain well-organized typesetting, making digitization less labour-intensive. However, secondary data can be reshaped by the motivations of the historical actors who were collating the data. This study compared data from 1876-1894 gathered originally by citizen scientists (primary data) and the secondary data founded upon the previous primary data, later published by the Finnish Society of Sciences and Letters as a series of phenological yearbooks. In the secondary data, the recorded numbers of taxa and their phenological stages appeared to be fewer and phenological events standardized, with an increased prevalence of agricultural phenology (at the cost of autumn phenology). Moreover, it seems the secondary data had been screened for potential outliers. While secondary sources may provide current phenologists with coherent sets of relevant data, future users must be aware of potential data reshaping resulting from the preferences of historical actors. These actors may weigh and limit the original observations according to their own criteria and preferences.

Does diurnal temperature range influence seasonal suicide mortality? Assessment of daily data of the Helsinki metropolitan area from 1973 to 2010.

Several studies show a peak in suicide rates during springtime and suggest differences in the seasonal variation of suicides. However, the seasonal distribution of the temperature impact on suicide is less clear. This study investigated the relationship between diurnal temperature range (DTR) on suicide mortality. Daily temperature and suicide data for Helsinki were analyzed for the period of 1973-2010 inclusive. Overall, DTR reached its maximum during the spring from mid-April to mid-June, which is also the season with highest suicide mortality in the study region. Specifically, the seasonal timing and maxima for both DTR and suicides vary from year to year. Time series analysis of DTR and suicide records revealed a significant (P<0.01) correlation between the springtime DTR maxima and suicide rates for males. No similar association could be found for females. These results provide evidence that a higher springtime DTR could be linked statistically to a higher seasonal suicide rate each spring, whereas the exact timing of the DTR peak did not associate with the seasonal suicide rate. A possible mechanism behind the springtime association between the DTR and suicides originates from brown adipose tissue (BAT) over-activity. Activation of BAT through the winter improves cold tolerance at the cost of heat tolerance. This might trigger anxiety and psychomotor agitation, affecting mood in a negative way. As a hypothesis, the compromised heat tolerance is suggested to increase the risk of death from suicide.

[Finnish suicide mortality from 1950 to 2009 in an European comparison]. / Suomalainen itsemurhakuolleisuus 1950-2009 eurooppalaisessa vertailussa.

BACKGROUND: Trends in suicide mortality in Europe from 1950 to 2009 were studied. MATERIAL AND METHODS: Data on 4,777,113 suicides in addition to the data on population were extracted from the WHO Mortality Database. RESULTS: In Europe, there was an increase in suicide mortality during the 1980s and the 1990s, followed by a decrease. The suicide mortality of Finnish men has decreased from the highest rate in the 1950s to the ninth place in the 2000s. In contrast, the suicide mortality of Finnish women is currently the second highest in Europe. CONCLUSIONS: Continuous work and research are needed to enhance suicide prevention at the regional level.

Plant phenological records in northern Finland since the 18th century as retrieved from databases, archives and diaries for biometeorological research.

Plant phenological data from northern Finland, compiled from several sources, were examined as potential biometeorological indicators of climate change since the 18th century. A common feature of individual series was their sporadic nature. In addition to waning enthusiasm, wartime hardships and crop failures had caused gaps in recording observations during the 18th and 19th centuries. The present study's challenge was to combine separate records, as retrieved from several historical archives and personal diaries, into a single continuous series. To avoid possible biases due to the variability of data availability each year, each phenomenon-specific mean series was transformed into normalized site-specific index series. These series were compared to each other and to a regional instrumental temperature series (years 1802-2011). The inter-phenomena correlations were high. Moreover, a strong biometeorological response of the phenological series, most especially to monthly mean temperature in May, and seasonally to the April through June temperatures, was identified. This response focused on slightly later spring months compared to the responses in an earlier study conducted for southern Finland. The findings encouraged us to compute a total phenological index series as an average of all available phenomenon-specific index series for northern Finland. The earliest phenological springs were found as a cluster in the recent end of the record, whereas the anomalously-late phenological spring could be found through the centuries. This finding could indicate that potential future warming could result in an earlier onset of phenological springs (i.e. as experienced by the plants), with a remaining possibility of late phenological springs. To conclude, it was shown that the indices are reliable biometeorological indicators of the April through June temperature variations and thus of the climate variability in the region.

Temperature-associated suicide mortality: contrasting roles of climatic warming and the suicide prevention program in Finland.

OBJECTIVES: Suicide is a notable cause of death worldwide, and while suicidal behavior appears to be associated with variations in temperature, no estimations are available of climate change impacts on suicide rates. The study aims to evaluate the influence of temperature on suicide mortality, especially on multi-decadal and longer time scales, that is, at scales on which the ongoing warming distinctly operates and is correspondingly appropriate for the current policy responses to warming climate. METHODS: Our results are based on an extraordinarily long record of deaths from suicide in Finland from 1751 to 2008, and a similarly long climatic record of ambient temperatures correlative of environmental change in the study region. RESULTS: We show that temperature variability explains more than 60 % of the total suicide variance up until the initiation of a national suicide prevention program. Despite ongoing warming, suicide rates have declined since the initiation of the program. CONCLUSION: By understanding the complexity of suicidal behavior as a response to ambient warming and the observed effects of interventions, our results underline the pressing need for a network of prevention programs to battle against temperature-mediated health hazards.

Variation and seasonal patterns of suicide mortality in Finland and Sweden since the 1750s.

OBJECTIVES: Suicide mortality varies in both the short and long term. Our study examines suicide mortality in Finland and Sweden from the 1750s until today. The aim of our study is to detect any seasonal peaks in suicide rates and examine their temporal evolution to suggest a mechanism that may explain such peaks. METHOD: We acquired the study material from the Finnish and Swedish cause of death statistics (257,341 deaths by suicide) and the relevant population gender structure data. We then separately calculated the annual male and female suicide rates per 100,000 inhabitants. We analysed the suicide peaks, calculating factors of proportionality for the available data by dividing the suicide rates in the peak months (May and October) by the annual suicide rates. RESULTS: Suicide rates in Finland and Sweden peak twice a year. Both men and women in both countries most often commit suicide in May. There is another peak in October, with the exception of Finnish men. These suicide peaks coincide with a temperature increase in May and the biggest annual drop in temperature in October. We also observed a monotonic long-term change in the Swedish statistics, but not in the Finnish data. Our hypothesis is that seasonal variation in suicide rates may be caused by abrupt temperature changes twice a year that trigger the activity in brown adipose tissue and deepen depression. CONCLUSION: While the overall suicide mortality rates varied considerably, the monthly proportions in May did not. This finding suggests a routine factor underlying the spring peak in suicide mortality.

Plant phenological dataset collated by the Finnish Society of Sciences and Letters.

Long records of phenological observations constitute data for ecological, climate, and global change studies. Here we provide a unique dataset of plant phenological observations made in boreal Europe between 1750 and 1965 from locations situated across historical and modern Finland, mostly between 70° and 60° N and 30° and 20° E. This dataset was generated initially by the efforts of several generations of volunteers representing naturalists whose field observations and notes had initially made the continuous collection of the data possible. In addition, the data were collated by the Finnish Economic Society and the Finnish Society of Sciences and Letters and published irregularly in the form of several monographs and periodicals by contemporary academic enthusiasts. Each phenological observation contains 11 features including: site name, site latitude, site longitude, scientific species name, phenological stage, and (if any) its substage, year, date (month and day) and the day since the summer solstice, the original literature source, and outlier estimate. Species names given originally either in Latin, Finnish, German, and/or Swedish were transformed into scientific species names. Moreover, outdated taxonomic names were updated as appropriate. Phenological stages that had been given originally either in German, Finnish, and/or Swedish were transformed into English and standardized by excluding synonyms. Site names were adopted at the county level, with corresponding latitude and longitude generated herein. The digitized dataset represents 265,478 observations of 985 taxa (assigned to variety/subspecies/species/hybrid/genus) for their 16 different phenological stages made in 371 locations across the region. We provide this dataset to support comparative studies and modeling projects, seeking to improve the understanding of terrestrial ecosystem dynamics and its responses to a changing environment from a local to a global scale. Use of this dataset for academic or educational purposes is encouraged as long as the data source is correctly cited with attribution given to this presentation of the data. Users are free to use and analyze the data; additionally, we would like to hear from other researchers who use this dataset in teaching or for their own research.

DOCU-CLIM: A global documentary climate dataset for climate reconstructions.

Documentary climate data describe evidence of past climate arising from predominantly written historical documents such as diaries, chronicles, newspapers, or logbooks. Over the past decades, historians and climatologists have generated numerous document-based time series of local and regional climates. However, a global dataset of documentary climate time series has never been compiled, and documentary data are rarely used in large-scale climate reconstructions. Here, we present the first global multi-variable collection of documentary climate records. The dataset DOCU-CLIM comprises 621 time series (both published and hitherto unpublished) providing information on historical variations in temperature, precipitation, and wind regime. The series are evaluated by formulating proxy forward models (i.e., predicting the documentary observations from climate fields) in an overlapping period. Results show strong correlations, particularly for the temperature-sensitive series. Correlations are somewhat lower for precipitation-sensitive series. Overall, we ascribe considerable potential to documentary records as climate data, especially in regions and seasons not well represented by early instrumental data and palaeoclimate proxies.

Food and fitness: associations between crop yields and life-history traits in a longitudinally monitored pre-industrial human population.

Severe food shortage is associated with increased mortality and reduced reproductive success in contemporary and historical human populations. Studies of wild animal populations have shown that subtle variation in environmental conditions can influence patterns of mortality, fecundity and natural selection, but the fitness implications of such subtle variation on human populations are unclear. Here, we use longitudinal data on local grain production, births, marriages and mortality so as to assess the impact of crop yield variation on individual age-specific mortality and fecundity in two pre-industrial Finnish populations. Although crop yields and fitness traits showed profound year-to-year variation across the 70-year study period, associations between crop yields and mortality or fecundity were generally weak. However, post-reproductive individuals of both sexes, and individuals of lower socio-economic status experienced higher mortality when crop yields were low. This is the first longitudinal, individual-based study of the associations between environmental variation and fitness traits in pre-industrial humans, which emphasizes the importance of a portfolio of mechanisms for coping with low food availability in such populations. The results are consistent with evolutionary ecological predictions that natural selection for resilience to food shortage is likely to weaken with age and be most severe on those with the fewest resources.

Food availability at birth limited reproductive success in historical humans.

Environmental conditions in early life can profoundly affect individual development and have consequences for reproductive success. Limited food availability may be one of the reasons for this, but direct evidence linking variation in early-life nutrition to reproductive performance in adulthood in natural populations is sparse. We combined historical agricultural data with detailed demographic church records to investigate the effect of food availability around the time of birth on the reproductive success of 927 men and women born in 18th-century Finland. Our study population exhibits natural mortality and fertility rates typical of many preindustrial societies, and individuals experienced differing access to resources due to social stratification. We found that among both men and women born into landless families (i.e., with low access to resources), marital prospects, probability of reproduction, and offspring viability were all positively related to local crop yield during the birth year. Such effects were generally absent among those born into landowning families. Among landless individuals born when yields of the two main crops, rye and barley, were both below median, only 50% of adult males and 55% of adult females gained any reproductive success in their lifetime, whereas 97% and 95% of those born when both yields were above the median did so. Our results suggest that maternal investment in offspring in prenatal or early postnatal life may have profound implications for the evolutionary fitness of human offspring, particularly among those for which resources are more limiting. Our study adds support to the idea that early nutrition can limit reproductive success in natural animal populations, and provides the most direct evidence to date that this process applies to humans.

Volcanic dust veils from sixth century tree-ring isotopes linked to reduced irradiance, primary production and human health.

The large volcanic eruptions of AD 536 and 540 led to climate cooling and contributed to hardships of Late Antiquity societies throughout Eurasia, and triggered a major environmental event in the historical Roman Empire. Our set of stable carbon isotope records from subfossil tree rings demonstrates a strong negative excursion in AD 536 and 541-544. Modern data from these sites show that carbon isotope variations are driven by solar radiation. A model based on sixth century isotopes reconstruct an irradiance anomaly for AD 536 and 541-544 of nearly three standard deviations below the mean value based on modern data. This anomaly can be explained by a volcanic dust veil reducing solar radiation and thus primary production threatening food security over a multitude of years. We offer a hypothesis that persistently low irradiance contributed to remarkably simultaneous outbreaks of famine and Justinianic plague in the eastern Roman Empire with adverse effects on crop production and photosynthesis of the vitamin D in human skin and thus, collectively, human health. Our results provide a hitherto unstudied proxy for exploring the mechanisms of 'volcanic summers' to demonstrate the post-eruption deficiencies in sunlight and to explain the human consequences during such calamity years.

Plant phenological data and tree-rings as palaeoclimate indicators in south-west Finland since AD 1750.

Plant phenological data and tree-rings were tested for their palaeoclimatic value in south-west Finland since AD 1750. The information from fragmentary, partly overlapping, partly non-systematically biased plant phenological records of 14 different phenomena (a total of 3,144 observations) was combined into one continuous time series of phenological indices. All site- and phenomenon-specific series were standardized to present an average of zero and standard deviation of one. The mean phenomenon-specific series were then averaged as arithmetic means for annually resolved time series representing the variability in the particular plant phenomenon. Consequently, each phenomenon-specific mean series was based on spatially normalized site-specific index series. These series were compared to each other, living-tree and subfossil tree-rings, and to early and modern meteorological time series. Phenological indices showed strong positive correlation with February to June temperatures. On the other hand, the correlations between phenological indices and precipitation data were around zero. Analysis using time-dependent running correlations showed non-stationary relationship between the tree-rings and phenological indices and observed spring temperatures. The skill of phenological data for reconstructing the spring temperatures was statistically proved.