trichoderma spp. are known as efficient plant growth promoting agents. hence, enrichment of soil by appropriate population of trichoderma is useful and important for effective plant growth promote. present study aimed to investigate the plant growth promoting effects of five strains of the genus trichoderma species include: trichoderma harzianum tr6, t. harzianum t22, t. asperellum t34, t. atro...

This paper offers an alternative way, based on the logistic population growth hypothesis, to yield transitional dynamics in the standard AK model with exogenous savings rate. Within this framework, we show that the dynamics of the capital stock per person and its growth rate can be non-monotonic over time. Moreover, even in the presence of negative growth, the capital stock per-capita can conve...

There is increasing evidence of indirect effects of hunting on populations. In species with sexually selected infanticide (SSI), hunting may decrease juvenile survival by increasing male turnover. We aimed to evaluate the relative importance of direct and indirect effects of hunting via SSI on the population dynamics of the Scandinavian brown bear (Ursus arctos). We performed prospective and re...

This article explores effects of adaptive intraguild predation on species coexistence and community structure in three species' food webs. Two Lotka-Volterra models that assume a trade-off between competition and predation strength are considered in detail. The first model does not explicitly model resource dynamics and is considered with both nonadaptive and adaptive intraguild predation; in t...

The phenotype of adults can be strongly influenced by the environmental conditions experienced during development. Consequently, variation in habitat quality across space and through time also leads to differences in the phenotypes of adults. This could create carry-over effects where differences in the natal habitat quality of colonizers influence population dynamics in new habitats. We tested...

Abstract. First, we systematize earlier results on the global stability of the model ẋ + μx = f(x(· − τ)) of population growth. Second, we investigate the effect of delay on the asymptotic behavior when the nonlinearity f is a unimodal function. Our results can be applied to several population models [7, 9-13] because the function f does not need to be monotone or differentiable. Specifically, ...

During man’s relatively brief existence on this planet, he has relied on the bounty of its flora and fauna for his existence. He has harvested wildlife for food, clothing, shelter, medicines, beasts of burden, pets, and companionship. Over most of this period, this harvesting and exploitation had little impact on those resources. Human population was very low, and most animal and plant populati...

This paper develops a uni ̄ed growth model that captures the historical evolution of population, technology, and output. It encompasses the endogenous transition between three regimes that have characterized economic development. The economy evolves from a Malthusian regime, where technological progress is slow and population growth prevents any sustained rise in income per capita, into a Post-M...

The population dynamics of preindustrial societies depend intimately on their surroundings, and food is a primary means through which environment influences population size and individual well-being. Food production requires labor; thus, dependence of survival and fertility on food involves dependence of a population's future on its current state. We use a perturbation approach to analyze the e...

In this paper, I present and discuss a potentially useful modeling approach for investigating population dynamics in the presence of disturbance. Using the motivating example of wildfire, I construct and analyze a deterministic model of population dynamics with periodic disturbances independent of spatial effects. Plant population growth is coupled to fire disturbance to create a growth-disturb...