Vol 9, No 2 (2018)

Overviews and lectures
Ten years of progress: analytic review of the first decade of journal functioning
Glagolev M.V., Sabrekov A.F., Filippova N.V., Lapshina E.D.

The analytic review of work of the scientific journal «Environmental Dynamics and Global Climate Change» (EDGCC) over the 10 years since the first publishing is presented here. Statistical (science metrical) data were summarized to reveal what papers were most interesting and useful for readers.
Two-year impact factor (IF) of the journal increases persistently. During last five years it shows five-fold increase reaching a certain level among other Russian journals of the respective category. Number of EDGCC authors (special issues were not considered) does not vary substantially: 10-16 authors are published in EDGCC each year (among the first authors – from 4 to 10). The Hirsch index also increases stably during all years of publication showing that authors with higher qualification start to submit their papers to the journal.
26 scientific journals were selected randomly among those where authors of EDGCC publish their papers to compare science metrics of EDGCC with other journals (based on 2016 data). Two-year IF based on Russian Science Citation Index of 70% of these journals was lower than IF of EDGCC. The half-live of EDGCC papers is close to the average value for our ensemble. The EDGCC mean Hirsch index was higher than Hirsch index of 63% of all journals selected for our study. The value of probability of citation after reading was the highest for the test sample. Bibliometric parameters of ten most cited EDGCC papers were also analyzed here.
Based on provided analysis following recommendations on improving EDGCC as scientific journals have been formulated: translation of papers into English, selection of manuscripts relevant to the journal topic, increasing the number of theoretical papers, improving the quality of experimental papers. Discussion section reviewed in a usual manner seems to be optimal decision to provide future development of the journal. New referee questionnaire modified according to the recommendations above for improvement of manuscripts quality is attached in appendix.

Environmental Dynamics and Global Climate Change. 2018;9(2):3-16
Experimental works
The experience of estimating the aboveground productivity dynamics of grass communities in the Malaya Sosva River floodplain (Nature Reserve "Malaya Sosva") taking into account weather, climate and hydrological features
Tyurin V.N.

This article is devoted to assessing the productivity of grass communities in the Malaya Sosva River floodplain (Reserve "Malaya Sosva"). The three-year studies (1986-1988) at six sample plots (SP) were conducted. The main goal was to evaluate the productivity and its relationship with hydrological and meteorological factors. The method of N.F. Khramtsova was used [1974], which allows to avoiding disturbance of vegetation on the SP, as well as performing statistical data processing. The obtained results reflected the close relationship of productivity with soil moisture, connecting to the position in the relief – aboveground biomass increases to the Malaya Sosva River. At the same time, the increase in biomass has a weak relationship with meteorological factors (temperature and precipitation), despite the weather contrasting seasons. The grass communities show relative stability by significant fluctuations in hydrological and weather conditions in different years. There is an inverse correlation between productivity and biodiversity. A similar trend was observed for the flood plain of the Ob River. But there is a significant range of values in the Ob River floodplain due to the extended flooding.

Environmental Dynamics and Global Climate Change. 2018;9(2):17-27
Long-term phenoclimatic averages of the Yuganskiy Nature Reserve territory and changes for 1961-2016
Zvyagina E.A., Pereyaslovets T.S.

In light of the observed global climate changes in recent decades, we studied the local climate indicators and explored the possible links between the spring and autumn phenophases and climate data changes in the Yuganskiy nature reserve (N 600 17’; E74054’ – N590 23’; E74000’) in 1982-2016. The collected climate data include daily average, maximum and minimum temperatures, daily precipitation amount and intensity, and number of days with precipitation of 0.1mm or more, monthly average of snow depths, dates of first and last occurrence of daily mean temperatures 0, +5, +10°С through the year. Timing of sap movement and leaf fall start were used as the spring and autumn indicators of birch (Bétula péndula ) phenology. The mean value of weather averages in the 30-year period of 1961-1990 was used as reference. Trends were calculated using linear least squares regression. Statistical significance was determined by calculating the standard error of the trend estimate.

We found that the annual mean temperature has increased from –1.9°С (1961-1990) to –0.8° С (1982-2016), with corroborating indicators including increased temperature of the coldest night of the year from –53°С (1961-1990) to –51.3° С (1982-2016) and increased frequency of significant positive temperature anomalies from 21% (1961-1990) to 37% (1982-2016). May, June, August and October nights have become successively warmer. The air temperature increase was not accompanied by a corresponding increase in precipitation.

Statistically significant trends toward earlier onset of spring and summer from 1982 to 2016 were observed. The date of the last spring freeze has been advancing by 6.1 days per decade since 1982. A freeze-free season has lengthened by 7.7 days per decade. Linear trend of the snowmelt timing was –3.7 days per decade. Permanent snow cover period has been shortening by 7.7 days per decade. The date of the first occurrence of the daily mean temperatures of +10° С has been advancing by 5.1 days per decade. However, the 0 -+5° С lag has been lengthening significantly by 9.2 days per decade, and the number of biologically effective degree days (base +5C) has not statistically changed.

Sap flux and leaf fall timing of B. pendula have been advancing almost simultaneously by 4.0 and 4.2 days per decade since 1985. Sap flux beginning and last spring freeze date have been found to be linearly correlated (r=0.904). The average lag of them was 5±1 days and has been lengthening by 3 days per decade (1985–2016).

Environmental Dynamics and Global Climate Change. 2018;9(2):28-39
Theoretical works
Delay differential equations as a tool for mathematical modelling of population dynamic
Glagolev M.V., Sabrekov A.F., Goncharov V.M.

The manuscript constitutes a lecture from a course “Mathematical modelling of biological processes”, adapted to the format of the journal paper. This course of lectures is held by one of authors in Ugra State University.

Delay differential equations are widely used in different ecological and biological problems. It has to do with the fact that delay differential equations are able to take into account that different biological processes depend not only on the state of the system at the moment but on the state of the system in previous moments too. The most popular case of using delay differential equations in biology is modelling in population ecology (including the modelling of several interacting populations dynamic, for example, in predator-prey system). Also delay differential equations are considered in demography, immunology, epidemiology, molecular biology (to provide mathematical description of regulatory mechanisms in a cell functioning and division), physiology as well as for modelling certain important production processes (for example, in agriculture).

In the beginning of the paper as introduction some basic concepts of differential difference equation theory (delay differential equations are specific type of differential difference equations) is considered and their classification is presented. Then it is discussed in more detail how such an important equations of population dynamic as Maltus equation and logistic (Verhulst-Pearl) equation are transformed into corresponsive delay differential equations – Goudriaan-Roermund and Hutchinson.

Then several discussion questions on using of a delay differential equations in biological models are considered. It is noted that in a certain cases using of a delay differential equations lead to an incorrect behavior from the point of view of common sense. Namely solution of Goudriaan-Roermund equation with harvesting, stopped when all species were harvested, shows that spontaneous generation takes place in the system.

This incorrect interpretation has to do with the fact that delay differential equations are used to simplify considered models (that are usually are systems of ordinary differential equations). Using of integro-differential equations could be more appropriate because in these equations background could be taken into account in a more natural way. It is shown that Hutchinson equation can be obtained by simplification of Volterra integral equation with a help of Diraq delta function.

Finally, a few questions of analytical and numerical solution of delay differential equations are discussed.

Environmental Dynamics and Global Climate Change. 2018;9(2):40-63

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