seyed akbar javadi; alireza khanarmooyi; Mohammad Jafari
Abstract
The relationship between vegetation and soil properties in Khojier National park, located in Tehran province was investigated. For this purpose, vegetation data was recorded in each plot, based along 3 tansects in each vegetation type. Minimal area method was used for plot size. Density and vegetatin ...
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The relationship between vegetation and soil properties in Khojier National park, located in Tehran province was investigated. For this purpose, vegetation data was recorded in each plot, based along 3 tansects in each vegetation type. Minimal area method was used for plot size. Density and vegetatin cover were determined. TWINSPAN and DCA tests were used to classify vegetation. Soil sample was taken from 0-20cm of soil depth then transferred to laboratory and prepared for analysis including soil texture, percentage of CaCo3, CaSo4, and pH, EC, P, Ca, Ma and N. For analysis of soil properties in relation to vegetation changes, a multivariate analysis method such as canonical correspondence analysis (CCA) was used. These analyzes were conducted using PC-ORD software. Results showed a significant correlation between vegetation and environmental factors. The most important soil properties affecting on vegetation types were gravel, clay, silt, sand, caso4, caco3, pH, EC, K and elevation. Statistical analysis of the results showed that the vegetation types had a significant difference in terms of percentage of Gravel, CaCo3, CaSo4, Sand, Clay.The most important soil properties affecting on vegetation types were gravel, clay, silt, sand, caso4, caco3, pH, EC, K and the height above sea level. Statistical analysis of the results showed that the vegetation types had a significant difference in view of percentage of Gravel, CaCo3, CaSo4, Sand, Clay.
Mostafa Naderi; Asghar Mosleh arany; Gholamhosein Moradi; Abdosalam Piri; Mehrdad Kuhzadian; Hamid Azimzadeh
Abstract
This research aimed at studying the vegetation and investigating the effects of physiographic,edaphic and geological factors upon distribution of plant communities in Manesht district in Ilamprovince. Sampling was done based on plant types and land unit map. The number of samples wasdetermined by Krebs ...
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This research aimed at studying the vegetation and investigating the effects of physiographic,edaphic and geological factors upon distribution of plant communities in Manesht district in Ilamprovince. Sampling was done based on plant types and land unit map. The number of samples wasdetermined by Krebs method. In total, 125 square sampling plots of 400 2 m area were selected byrandom systematic method. To determine soil factors, two soil samples (0–30, 30-90 cm deep) werecollected from each land unit and physico-chemical parameters were measured. Using TWINSPAN,vegetation of study area was classified and then PCA and CCA were used to investigate therelationship between vegetation and environmental factors. Based on TWINSPAN, four vegetationgroups were recognized. According to TWINSPAN results, four ecological groups were identifiedthat first and second groups with 31 and 46 sample plots, respectively and by Quercus barantti,Crataegus pontica and Acer monspessulanum, as indicator species, are more calciphiles thananother groups. The first three axes of the PCA accounted for 62.83%, 23.45% and 13.72% of thetotal plant cover variability, respectively. Also based on Mont Carlo analysis, first and second axeswith 0.68 and 0.48 eigenvalue, accounted for 28% and 19% of the variability, respectively and thecorrelation coefficient of axes and species is 0.98. According to PCA and CCA, Formation, organicmatter and lime were the most important factors on establishing of ecological groups.
E Ghehsareh Ardestani; M Bassiri; M Tarkesh; M Borhani
Volume 63, Issue 3 , December 2010, , Pages 387-397
Abstract
Our planet is threatened by nuclear wars, climate change and degradation of biodiversity. The first two dangers are relatively focused on, but biodiversity degradation is not properly considered yet. Species diversity is mostly composed of biodiversity and is considered an index of changes in ecosystems. ...
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Our planet is threatened by nuclear wars, climate change and degradation of biodiversity. The first two dangers are relatively focused on, but biodiversity degradation is not properly considered yet. Species diversity is mostly composed of biodiversity and is considered an index of changes in ecosystems. Many of researchers think of higher species diversity as an index of bio-system’s stability. This research aimed to study parametric models of species diversity on range vegetations of study sites and relationship of ecological factors such as climate, soil and topography with diversity index. Four range sites were selected on different geographic areas in Isfahan province and randomly- systematic sampling was conducted to collect density data on plant species by quadrates along transects of each site during six years (2002-2007). Broken stick, log normal, logarithmic series and geometric series models were fitted for each site, and log normal showed to be the most proper model of distribution with P>0.05. LSD’s test indicated a significant different at ?=1% level between species diversity of steppe1 and semi-steppe2 sites. Log normal model seemed to be the most proper model in all sites. Generally, when this model is fitted successfully communities are considered stable. On the basis of some related studies with this research, Hill ( ) showed to be most proper index for species diversity in study sites, therefore effects of ecological factors such as soil, climate and topography on this index were studied by CCA method. Results of CCA revealed a high positive correlation between species diversity and percent organic matters of soil as well as precipitation levels and negative correlation with temperature.
