The present study provides a vegetation analysis and species distribution at 50 sites, emphasizing the environmental factors that affect species distribution. A total of 74 plant species belonging to 67 genera and rel...The present study provides a vegetation analysis and species distribution at 50 sites, emphasizing the environmental factors that affect species distribution. A total of 74 plant species belonging to 67 genera and related to 23 families of vascular plants are recorded. Asteraceae, Poaceae, Chenopodiaceae, Brassicaceae, Fabaceae and Zygophyllaceae are the largest families, and therophytes (41.89) and chamaephytes (24.32%) are the most frequent, indicating a typical desert life-form spectrum. Chorological analysis revealed that 25 of the studied species were Mediterranean taxa, Saharo-Sindian chorotypes, either pure or penetrated into other regions, comprised 47 species. After application of the TWINSPAN and DCA programs, 4 vegetation groups (A-D) were identified, groups A and B were dominated by Achillea santolina, group C was codominated by Zygophyllm coccinum and Launaea spinosa and group D was dominated by Leptadenia pyrotechnica. Groups A and B may represent the vegetation types of the Western Mediterranean coast of Egypt, while groups C and D may represent the Wadi Hagul. The linear correlation of soil variables with the importance values of some dominant species and the application of Canonical Correspondence Analysis (CCA-biplot) indicates significant associations between the floristic composition of the studied area and the edaphic factors such as electrical conductivity, pH, calcium carbonate, sulphates, bicarbonate, cations (Na+, K+, Ca++ and Mg++) and PAR.展开更多
In this floristic study from sea level to timberline in the westernmost Hyrcanian forests,1302 plant specimens within 166 releves were identified.There were 649 taxa of vascular plants belonging to 349 genera and 95 f...In this floristic study from sea level to timberline in the westernmost Hyrcanian forests,1302 plant specimens within 166 releves were identified.There were 649 taxa of vascular plants belonging to 349 genera and 95 families.Poaceae had the most taxa(61),followed by Asteraceae(59),and Rosaceae(53).Genera with the greatest species richness included Alchemilla and Carex,each with 16,Veronica with 15,and Poa,Geranium and Rumex each with 9.Hemicryptophytes(43.3%)were the dominant life form.Chorological analysis showed 31.2%Euro-Siberian elements.Of the total number of species,10.9%(70)were endemic or subendemic to Iran.Species diversity indices at different altitudes were also compared.展开更多
Aims The aim of the study was to discover what set of variables best explains the transition from warm to mesic forest vegetation.Based on various variables grouped into sets(geomorphological,ecological,structural,soi...Aims The aim of the study was to discover what set of variables best explains the transition from warm to mesic forest vegetation.Based on various variables grouped into sets(geomorphological,ecological,structural,soil characteristics and chorological),six models were built and tested by generalized additive mixed models(GAMMs).We assumed that each set of variables has different explanatory power.Our aim was to compare the six different models(sets of variables),to test which model best explains the species turnover in forest communities along the transition between warm and mesic temperate forests and to try to find reasons for the different explanatory power of the models.Methods The research took place in the southern part of the Balkan Peninsula.Field sampling was done according to standard methods.The gradient from warm to mesic forests was defined as the turnover of species and evaluated by projection of samples on the first unconstrained DCA axis.Geomorphological,ecological,structural and soil characteristics,together with chorological sets of variables,were regressed on the turnover of species composition.Based on the five sets of variables,six models were constructed and tested by generalized additive mixed models.Important Findings Ecological conditions best explain the change of forest communities along the gradient;evolution and the development of vegetation reflected in chorotypes are also of high importance;geomorphology and structure seem not to change so dramatically and soil shows the least significant differences of all.Ecological variables are the most important set of variables in the transition between warm and mesic temperate forests but eco-evolutionary dynamics after the Pleistocene should also be taken into consideration.展开更多
文摘The present study provides a vegetation analysis and species distribution at 50 sites, emphasizing the environmental factors that affect species distribution. A total of 74 plant species belonging to 67 genera and related to 23 families of vascular plants are recorded. Asteraceae, Poaceae, Chenopodiaceae, Brassicaceae, Fabaceae and Zygophyllaceae are the largest families, and therophytes (41.89) and chamaephytes (24.32%) are the most frequent, indicating a typical desert life-form spectrum. Chorological analysis revealed that 25 of the studied species were Mediterranean taxa, Saharo-Sindian chorotypes, either pure or penetrated into other regions, comprised 47 species. After application of the TWINSPAN and DCA programs, 4 vegetation groups (A-D) were identified, groups A and B were dominated by Achillea santolina, group C was codominated by Zygophyllm coccinum and Launaea spinosa and group D was dominated by Leptadenia pyrotechnica. Groups A and B may represent the vegetation types of the Western Mediterranean coast of Egypt, while groups C and D may represent the Wadi Hagul. The linear correlation of soil variables with the importance values of some dominant species and the application of Canonical Correspondence Analysis (CCA-biplot) indicates significant associations between the floristic composition of the studied area and the edaphic factors such as electrical conductivity, pH, calcium carbonate, sulphates, bicarbonate, cations (Na+, K+, Ca++ and Mg++) and PAR.
基金University of Isfahan,Education and Postgraduate Studies。
文摘In this floristic study from sea level to timberline in the westernmost Hyrcanian forests,1302 plant specimens within 166 releves were identified.There were 649 taxa of vascular plants belonging to 349 genera and 95 families.Poaceae had the most taxa(61),followed by Asteraceae(59),and Rosaceae(53).Genera with the greatest species richness included Alchemilla and Carex,each with 16,Veronica with 15,and Poa,Geranium and Rumex each with 9.Hemicryptophytes(43.3%)were the dominant life form.Chorological analysis showed 31.2%Euro-Siberian elements.Of the total number of species,10.9%(70)were endemic or subendemic to Iran.Species diversity indices at different altitudes were also compared.
基金National Park Galičica,Research Centre of the Slovenian Academy of Sciences and Arts,Slovenian Research Agency(P1-0236).
文摘Aims The aim of the study was to discover what set of variables best explains the transition from warm to mesic forest vegetation.Based on various variables grouped into sets(geomorphological,ecological,structural,soil characteristics and chorological),six models were built and tested by generalized additive mixed models(GAMMs).We assumed that each set of variables has different explanatory power.Our aim was to compare the six different models(sets of variables),to test which model best explains the species turnover in forest communities along the transition between warm and mesic temperate forests and to try to find reasons for the different explanatory power of the models.Methods The research took place in the southern part of the Balkan Peninsula.Field sampling was done according to standard methods.The gradient from warm to mesic forests was defined as the turnover of species and evaluated by projection of samples on the first unconstrained DCA axis.Geomorphological,ecological,structural and soil characteristics,together with chorological sets of variables,were regressed on the turnover of species composition.Based on the five sets of variables,six models were constructed and tested by generalized additive mixed models.Important Findings Ecological conditions best explain the change of forest communities along the gradient;evolution and the development of vegetation reflected in chorotypes are also of high importance;geomorphology and structure seem not to change so dramatically and soil shows the least significant differences of all.Ecological variables are the most important set of variables in the transition between warm and mesic temperate forests but eco-evolutionary dynamics after the Pleistocene should also be taken into consideration.
