نتایج جستجو برای: population density

تعداد نتایج: 1071798  

Journal: رستنیها 2009
A.H. MOHAMMADI M. HAGHDEL Z. BANIHASHEMI,

Aspergillus species are major causes of pre- and post-harvest degradation of agricultural products. During 2004-07, the presence and population of Aspergillus species were studied in various fields and orchards of Fars and Kerman Provinces. Soil samples were collected from 0-40 cm depth. Isolates were recovered from soil using modified Czapek, AFPA and SPDA media. Based on macroscopic and micro...

In order to evaluate the possible correlation between the tree density and the human population density, the forested area in Nav Asalem district located in Guilan Province was selected. The descriptors of tree number and basal area per hectare as well as the stand density index were used to determine the tree density, which was conducted from a 2014 forest inventory including 62 cluster (558 p...

Journal: :environmental resources research 2014
hossein varasteh moradi mohamed zakaria scott . k. robinson

forest fragmentation results in a loss of forest interior and an increase in edge habitat. we studied how understorey bird community composition and habitat variables changed along an edge-to-interior gradient in a 1248-ha lowland rainforest patch in peninsular malaysia. birds and environmental variables such as vegetation structure and litter depth were detected within a 25-m radius of each of...

Journal: :حفاظت گیاهان 0
(مقاله کوتاه پژوهشی)مهرداد عمواقلی طبری حسن قهاری

abstract the effect of different larval density of chilo suppressalis walker was evaluated through 2006-2008 on rice infestation in controlled condition of the cages. the results indicated that there were significant effects between dead hearts, white heads and crop yield. the highest dead hearts and white heads were related to the treatment of 32 larvae per m2 and the lowest ones were obtained...

Journal: :international journal of advanced biological and biomedical research 2015
aynalem gebre bizuayehu tesfaye beemnet mengesha kassahun

objective: taro (colocasia esculenta l. schott) is a perennial root crop that belongs to araceace family.  it is widely cultivated as a staple food in africa, asia and pacific islands. despite its importance, there is limited information on many aspects of the crop. in order to obtain data that can support improved and sustainable taro production, a field trial was conducted to study the effect...

Journal: :journal of agricultural science and technology 2010
r. kianpour y. fathipour k. kamali b. naseri

bionomics of aphis gossypii glover and its predators coccinella septempunctata l. and hippodamia variegata goeze were studied in varamin (tehran province) during 11th may to 5th october 2006 on eggplant crop, with the interaction (density dependence) between the aphid and either of the predators determined. the reliable sample size (number of leaves) with a maximum variation of 6.73% was about ...

2009
Anne Hendrikse Raymond Veldhuis Luuk Spreeuwers

Second order statistics estimates in the form of sample eigenvalues and sample eigenvectors give a sub optimal description of the population density. So far only attempts have been made to reduce the bias in the sample eigenvalues. However, because the sample eigenvectors differ from the population eigenvectors as well, the population eigenvalues are biased estimates of the variances along the ...

Journal: :Journal of Population Economics 2005

Journal: :Philosophical transactions of the Royal Society of London. Series B, Biological sciences 2009
Russell Lande Steinar Engen Bernt-Erik Saether

The evolution of population dynamics in a stochastic environment is analysed under a general form of density-dependence with genetic variation in r and K, the intrinsic rate of increase and carrying capacity in the average environment, and in sigma(e)(2), the environmental variance of population growth rate. The continuous-time model assumes a large population size and a stationary distribution...

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