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by
A. Javanshir |
Total Records (
5 ) for
A. Javanshir |
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T. Ebrahimi Gajoti
,
V. Haciyev
,
A. Javanshir
,
H. Nosrati
,
A. Razban Haghighi
,
A. Eimanifar
and
N. Stewart Jr.
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Problem statement: Plants associations differ in relation to environmental gradients. Therefore, it is necessary to study the interaction between ecological factors and vegetation. Approach: In this study vegetation and flora of Sutan-Chay Basin in Arasbaran was investigated using Braun Blanquet method as physiognomic floristic. Sampling of soil and vegetation was carried out by selecting areas with homogenous plant compositions. The surface area of releves was determined using Nested Plot method to obtain the Minimal area. Classification of releves was conducted based on the presence and cover percentage of species using cluster analysis and Jaccard index similarity. CCA was used to determine the relationship between the groups and ecological factors and the most important factors in separating the groups and distribution of the species. The classification of releves based on Jaccard’s similarity coefficient and cluster analysis showed 6 different groups. Results: Dendrogram of cluster analysis based on these methods showed six associations: Astragaleto aureus-Thymetum kotschyanus, Poeto bulbosa-Festucetum ovina, Carpinetum betulus ،Quercetum macranthera, Paliuretum spina-christii, Juniperetum foetidissima. Canonical Correspondence Analysis (CCA) was used to determine the most important environmental factors on plant groups. This method of multivariate showed that pH, TNV%, soil texture, clay percentage, altitude and aspects had higher effect on separation of plant groups, which had correlation with axes 1 and 2 of ordination. Conclusion: Among the environmental factors the altitude has most important effect on plants distribution. With understanding of relationship between ecological factors and plant associations in a given area, it is possible to apply the obtained results in management and revival of forestland and rangeland. |
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M. Khoramivafa
,
S. Zehtab Salmasi
,
A. Dabbagh Mohammadi Nassab
,
A. Javanshir
and
A. Mohammadi Shuti
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In order to evaluate the intra- and inter specific competition of corn (Zea mays L.) and pumpkinseed (Cucurbita pepo var. styriaca) by reciprocal yield model, two years field experiments were conducted at the research station of faculty of Agriculture, University of Razi, Kermanshah, Iran, in 2003-2004. The experiments laid out as factorial based on randomized complete block design. The interspecific competition of corn on pumpkinseed was greater than that of Pumpkinseed`s on corn. Corn Intraspecific competition in second year was greater than that first year; due to delay in planting date. According to relative competitive effects, intraspecific competition affected corn plants less than pumpkinseed plants. |
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A. Javanshir
,
M. Shapoori
and
S. Jamili
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Macro benthic invertebrate assemblages were investigated
monthly, from March 2006 to March 2007, at six stations in Tajan river
estuary, a south eastern Caspian Sea coastal estuary, in order to estimate
secondary production consumable for extensive finger fish releasing and
to investigate the factors affecting this production. Benthic assemblages
comprised 9 taxa, of which Ballanus sp., Chironomus plumosus
and Cerastoderma lamarki were the main contributors to both overall
biomass and secondary production. Annual secondary production varied from
4.55 g AFDW m-2 year-1 (Ash Free Dry Weight), in
the upper Tajan estuary, to 78.06 g AFDW m-2 year-1
(Ash Free Dry Weight) in the center of the estuary area. Multivariate
correlations between environmental variables and the Macro benthic assemblage
biomass highlighted the role of the water level, temperature, sediment
organic carbon content and dissolved oxygen in the differentiation of
the communities in the estuary. Composition, biomass and secondary annual
production of Macro benthic communities were dramatically affected by
changes in water residence time and summer drought crises. The isolation
of this habitat limits the recovery of other invertebrate benthic assemblages
during drought periods. Only populations of two species, Balanus sp.
and C. plumosus, seemed to be able to recover quickly after the
drought crises, which, in turn, could compromise the overall secondary
production, with negative effects on the released fish survival. During
summer water renewal, when agricultural activity is intense and nutrient
inputs should be regulated in this estuary to reduce the risk of benthic
mass mortality and to ensure a sustainability of this environment. |
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M. Shapoori
,
A. Javanshir
,
S. Jamili
,
M. Fallahi
and
R. Changizi
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The phytoplankton community composition, abundance and
size-fractionated biomass (chlorophyll a) along with various physical
and chemical parameters were assessed in Tajan estuary, in South Caspian
Sea Basin. Monthly sampling was conducted at 6 stations. Based on results,
the mouth or formed estuary could be categorized in three different classes.
Category 1: station essentially related to river input and low net production
(vary between 13.8 and 46.4 mg m-3 year-1. Category
2: consists of high net production (between 277.9 and 330.4 mg m-3
year-1) and mild consumption of (8.4 to 32.5 mg m-3
year-1). The 3rd category is considered to be in the middle
of two above values from productivity point of view with (236.7 to 240.2
mg m-3 year-1) and relatively mild consumptions
of (20.9 to 92.4 mg m-3 year-1). It seems that importance
of such areas is much more in their nutrient inlet of the river from upper
mouth. Net primary productions were high in the center of estuary with
values near to 277 mg m-3 year-1. Selected station
in lower mouth situated in the adjacent area inlet also showed high concentrations
of 330 mg m-3 year-1, which suggests the existence
of a nutrient front where fresh waters originated from rivers (rich in
nutrient and phytoplankton decomposition materials) joint salt waters
of the sea. In these stations phytoplankton has not enough time to be
consumed because of soft sediments instability and inevitably is added
to south Caspian basin production. Also primary production among months
and seasons shows fluctuations, perhaps related to water inlet availability
and residence time. There suggests a correlation between primary production
and river discharge in different selected stations. |
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M.R. Rahimibashar
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A. Esmaeili-Sary
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S.A. Nezami
,
A. Javanshir
,
S.M. Reza Fatemi
and
S. Jamili
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The aim of this study was to examine spatial and temporal variability in phytoplankton and zooplankton abundance and diversity in Sefid-Rood River Estuary (SRE). Variability of Chlorophyll a and inorganic nutrient concentration were determined during a year (November 2005- October 2006) in five sampling stations. Total chlorophyll a concentration during the investigation ranged between zero to 22.8 μg L-1 and the highest levels were consistently recorded during Summer and the lowest during winter with a annual mean concentration 4.48 μg L-1. Nutrient concentration was seasonally related to river flow with annual mean concentration: NO2 0.05±0.2, NO-3 1.13±0.57 and NH+4 0.51±0.66 mg L-1, total phosphate 0.13±0.1 and SiO2 5.68±1.91 mg L-1. Bacillariophytes, Cyanophytes, Chlorophytes, Pyrophytes and Euglenophytes were the dominant phytoplankton groups in this shallow and turbid estuary. The diversity and abundance of phytoplankton had a seasonal pattern while Diatomas and Chrysophytes were dominant throughout the year but Cyanophytes observed only during the Summer. Zooplankton community structure was dominated by copepods which 68% of the total Zooplankton. In the winter and summer seasons two increased in the number of zooplankton community and usually toward the sea had occurred. Zooplankton also showed a significant spatial and temporal variation. The high turbidity and temperature prime characteristics of SRE seem to be determining factors acting directly on Phytoplankton and Zooplankton temporal variability and nutrient fluctuations. Everywhere in this estuary nutrients appeared to be in excess of algal requirement and did not influence an phytoplankton and zooplankton composition. Also there was a positive correlation between chlorophyll a and temperature and a negative one with DIN and TP. |
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