Vol. 9, No. 4 (2021): Regular Issue

The aim of the study is to assess the response of plantations in general and individual trees to thinnings of different intensity. The research target is forests located on the forestry fund lands of the Bashkortostan Republic. The research is based on the method of test areas used in complete enumeration and selection of sample trees of Tilia cordata Mill. There was conducted an analysis of variability of morphological characteristics of lime trees after thinnings of different intensity in young stands (from 50 to 75%). After cleaning from 1 to 10 shoots were on mother stumps. The analysis showed that thinnings have a direct impact on formation of trunks and crowns of target trees: low intensity thinning provides a strong variation (the crown length -- 21.2%, the crown projection diameter -- 37.9%), while high intensity cutting brings in less change (the crown length -- 11.7%, the crown projection diameter-- 18.0%). The felling intensity influenced the nature of flowering and distribution of flowers: on the plot with an intensity of 75% and 1 shoot on the stump, there is the highest occurrence of flowering trees -- 20.8%; while on the plot after thinning with 50% intensity and an average number of 10 shoots on the stump, 55.3% of trees didn't bloom. In general, there are 4.2-20.8% trees with very good flowering and uniform arrangement of flowers throughout the crown. Studies have found that thinning of young stands in aspen forests, located close to beekeeping apiaries, makes it possible to restock the plots with nectar plantations of predominantly small-leaved lime trees.

Though the government has ruled ``Say No to Plastic'', plastic usage is increasing day by day. It is observed since last three decades that each process of plastic creates pollution affecting degradation of environmental resources like air, soil and water. The proposed mathematical model contains these three pollutions with its issues having a dynamical system of nonlinear differential equations. Feasible region contains three equilibrium points pollution-free, water-pollution free and optimum issue point. Basic reproduction number and center manifold theory is used for analyzing the local stability of a model. Castillo-Chavez theory with detailed computation has been used to check global dynamical behavior of equilibrium points and also gives the existence of backward bifurcation of plastic usage. To optimize the pollution, optimal control has been applied to the system. Graphical analysis is carried out.

In this paper, we have discussed the dynamical behaviour of a delayed induced harvested predator-prey model incorporating both effects of fear (felt by prey) and additional food (provided to the predator). Hence we have considered selective harvesting terms in both the species that provides some fixed elapsed time to prey and predator population before they are harvested. Ecologically, harvesting of population are restrained below certain age to protect juvenile population. Also the reproduction of prey population can be greatly hindered due to the influence of fear effect. However, to increase the growth rate of predator and to decrease the predatory attack rate on the prey population, it is necessary to incorporate additional food to the predator for maintaining ecological balance. Consideration of age-selective harvesting together with fear effect and additional food compel the proposed system to exhibit Hopf-bifurcation around the coexistence equilibrium point. For better ecological community management, our study reveals the fact that harvesting delay and harvesting intensities should be maintained. Numerical simulations have been performed to validate the analytical findings.

In Microbial-Induced Calcite Precipitation (MICP) has been introduced in the field of ground improvement. The applications of this method shows potential in several fields like improvement of strength and durability of concrete, bricks, sand permeability, soil strength etc., and various works are being conducted on these fields in the current scenario. To promote the engineering properties of the material after MICP treatment, need to have study the relevant crystal mineralization process and analyses the influences on the soil engineering properties. The main aim of this paper is to analyses the behavior of various bio geo chemical processes between the soil mineralogy, solid soil grains, water or fluid, and gases in the voids, beneath the soil surface after employing microbes as strengthening consultant. Geotechnical applications currently being inquired which includes the process of cementation of sands, to enhance bearing capacity and liquefaction resistance, Carbon sequestration, erosion control of soil, controlling the groundwater flow, and remediation of soil and groundwater impacted by metals and radio-nuclides.

A modern understanding of crop growth productivity allows us to expand our ecological culture using the land fund. However, the impact of industrial enterprises determines the structural content and increase of soil pollution level. The relevance of this study is determined by the fact that the formation of measures that would contribute to reducing soil pollution is currently based not only on the economic assessment of measures, but also on reducing the allowable impact on environmental metabolism and maintaining balance in the circulation of substances. The novelty of the study is determined by the need to develop a model that takes into account the capabilities of modern biological agents to form complex chemical complexes that can reduce the concentration of heavy metals. The authors propose a model that can provide a solution to the problems of the separation of heavy metals with the formation of a complex of a biologically utilizable type. The authors determine the accumulation complexes, their chemical composition and, if necessary, the reagents used. The practical significance of the study is formed due to the strategic development of the chemical complex. In this vein, considered the possibility of using chemical compounds that can be used as producers for the formation of a new fertile layer after the accumulation of heavy metals in the skeletal structure of plants.

The present pursuit concerns itself with an updated real predator-prey system based on a fear factor induced by interacting species with nonlinear predator harvesting unlike constant or linear harvesting. The diversification of system parameters gives rise to different categories of system dynamics. The system under consideration does experience bifurcation (saddle-node, transcritical and Hopf-Andronov) about the co-existence equilibrium position with respect to the choice of fear factor or nonlinear harvesting factor as a parameter of significance. The direction of the Hopf bifurcation together with the stability of the bifurcating periodic solutions are perceived through an explicit algorithm duly established by making use of the normal form and central manifold theory. The findings of the present investigation reveal that the fear factor or nonlinear harvesting factor bears the potential to influence the dynamical scenario of the interacting species remarkably.

This study examines the effects of the environmental strategy and the Management Control System (MCS) Package on management performance in Brazilian companies. A questionnaire prepared by Roetzel et al (2014) was applied to the companies listed as the 150 best companies to work in Brazil, and the sample consists of 73 respondents. Structural equation modeling was used to analyze the hypotheses. The environmental strategy positively influences the MCS Package. The MCS Package positively influences managerial performance. It was also found that cybernetic and cultural controls are the package's most comprehensive elements of MCS, a result that is consistent with Roetzel et al (2014), however, in the Brazilian scenario, were the administrative controls and not the remuneration and rewards that demonstrated less important role. The analysis of the interaction of these elements can instigate managers as to the importance of studying environmental issues in the Brazilian scenario, in order to broaden the discussion on an integrated environmental policy. Analysis of the effects of the environmental strategy and the MCS Package on management performance contribute to the consolidation of theoretical principles and can be essential for proposing sustainable development policies. Although these interactions were tested in the study by Roetzel et al (2014), the perception of managers may differ in contexts with different environmental management strategies.