Radial Growth Decline of White Spruce (Picea glauca) During Hot Summers without Drought: Preliminary Results from a Study Site South of a Boreal Forest Border

Here we investigate the possible future response of white spruce (Picea glauca) to a warmer climate by studying trees planted 90 years ago near the southern limit of their climate tolerance in central New York, 300 km south of the boreal forest where this species is prevalent. We employed high-frequency recording dendrometers to determine radial growth phenology of six mature white spruce trees during 2013-2017. Results demonstrate significant reductions in the length of radial growth periods inversely proportional to the number of hot days with air temperature exceeding 30 oC. During years with very hot summers, the start of radial growth began about 3 days earlier than the 2013-2017 average. However, in those same years the end of radial growth was also about 17 days earlier resulting in a shorter (70 versus 100 day), radial growth season. Abundant (350-500 mm) summer precipitation, which resulted in soil moisture values of 20-30% allowed us to dismiss drought as a factor. Instead, a likely cause of reduced radial growth was mean temperature that exceeded daily average of 30^oC that lead to photoinhibition.

Why companies succeed or fail: corporate cycles and firm function in tandem

Purpose This paper aims to underscore the need for developing a model of corporate cycles, which can explain how corporations rise, decline and fall in the marketplace. Design/methodology/approach This is a conceptual study that draws on prior theoretical and empirical insights of the entrepreneurial, managerial and social functions of the firm to develop a model of corporate cycles. Findings Firms that pass the test of the market and live for a long time, undergo cycles, expansions and contractions, driven by successes and failures in the way they configure and execute their entrepreneurial, managerial and social, functions. Practical implications A model of corporate cycles can explain how momentum rises and falls on Wall Street. It can also help predict revenue growth, a key variable in equity valuation models. Originality/value The originality of this study stems from a constructive synthesis of different concepts and theories of the firm to explain firms’ growth, decline and fall in the marketplace.

Rhizospheric Fungal Diversities and Soil Biochemical Factors of Fritillaria taipaiensis over Five Cultivation Years

Fritillaria taipaiensis is a valuable traditional Chinese medicinal plant that has experienced continuous decline over its cropping area. The present study aims to explore the reasons for the quality and growth decline. The fungal diversities and biochemical factors in its rhizospheric soils with cultivation duration from 1 up to 5 years were analyzed and compared. The results showed that rhizospheric fungi of F. taipaiensis belong to six phyla, including Neocallimastigomycota, Glomeromycota, Basidiomycota, Chytridiomycota, Zygomycota and Ascomycota. Thirteen genera (Pseudogymnoascus, Fusarium, Mortierella, Colletotrichum, Laetinaevia, Gibberella, Synchytrium, Lysurus, Trichocladium, Volutella, Monoblepharis, Aquamyces and Trichoderma) constituted the “core community” in the rhizosphere of F. taipaiensis. The dominant fungal genera varied significantly in rhizospheric soils with different cultivation years. The abundance of fungal species in the soil declined with the cultivation year generally. The pH, available P, organic matter and urease activity were the primary factors determining the fungal community composition in the rhizosphere. The content of organic matter, available N, P and K and the activities of urease and alkaline phosphatase decreased with cultivation years. The soil pH increased with cultivation years and was unsuitable for F. taipaiensis growth. These features suggested that long-term single planting altered the fungal community structure, fertility conditions and soil enzyme activities in F. taipaiensis rhizospheric soils, which could be detrimental for plant growth and quality.

Dwarf Mistletoe and Drought Contribute to Growth Decline, Dieback and Mortality of Junipers

Rising temperatures and aridification, combined with the stressing effect of some hemiparasitic plants such as mistletoes, may contribute to reduce vigour and growth of trees and shrubs leading to dieback and increasing mortality. This has been rarely explored in pioneer shrubs such as junipers, which are assumed to be more drought tolerant than coexisting trees. To test these ideas, we reconstructed radial growth patterns of common junipers (Juniperus communis L.) with different crown cover and infestation degree by dwarf mistletoe (Arceuthobium oxycedri (DC.) M. Bieb.) in two sites with contrasting aspect and water availability located in north-eastern Spain. We used dendrochronology to study the response of junipers’ radial growth to climatic factors (temperature, precipitation, and soil moisture), an index of drought severity, and mistletoe infestation. Juniper growth was constrained by elevated temperatures and low precipitation leading to drought during the growing season. Infestation by dwarf mistletoe contributed to a short-term growth decline in junipers. The interaction between low summer precipitation and high dwarf mistletoe infestation constrained juniper growth, particularly in the north-oriented wetter site, where hosts presented higher growth rates during wet periods. The negative impact of low summer precipitation on juniper growth overrides the effects due to dwarf mistletoe infestation. Aridification and mistletoe infestation could trigger dieback and mortality of shrubs slowing down successional dynamics and delaying shrub encroachment into former croplands and grasslands.

Quantifying the preventive effect of wearing face masks

An important task in combating the current Covid-19 pandemic lies in estimating the effect of different preventive measures. Here, we focus on the preventive effect of enforcing the use of face masks. Several publications study this effect, however, often using different measures such as: the relative attack rate in case-control studies, the effect on incidence growth/decline in a specific time frame and the effect on the number of infected in a given time frame. These measures all depend on community-specific features and are hence not easily transferred to other community settings. We argue that a more universal measure is the relative reduction in the reproduction number, which we call the face mask effect , E FM . It is shown how to convert the other measures to E FM . We also apply the methodology to four empirical studies using different effect-measures. When converted to estimates of E FM , all estimates lie between 15 and 40%, suggesting that mandatory face masks reduce the reproduction number by an amount in this range, when compared with no individuals wearing face masks.

The migration component in the demographic development of Russia in the post-war period (1951–2020)

The article discusses possible combinations of the impact on the dynamics of the population of migration growth (decline) and natural decline (increase). Variants of combinations with the corresponding values of natural and migration movements are shown using examples of the demographic dynamics of Russia. Reliable information about the migration movement of the population refers only to the time that began in the 50s. It is distributed over periods that differ in the nature of the impact of the reproductive and migration components on demographic dynamics. During these periods spanning seventy years, the country's population increased by almost 44 million. In the first 25 years, there was a migration decline, more than offset by natural population growth. Then migration, along with natural movement, acted as a component of population dynamics. Due to natural growth, the population increased to the 1951 level. by 33.8 million people. The migration component accounted for 10.6 million people. Their ratio was 3/4 to 1/4. It is shown that in the second half of the tenth years of the twenty-first century, Russia entered a difficult demographic time for it, aggravated by the fact that by now in the new abroad the migration potential oriented towards Russia has significantly decreased