Kobra Khadem; Mohammad Jankju; Mansour Mesdaghi
Volume 22, Issue 2 , August 2015, , Pages 231-239
Abstract
Curved pits have been constructed in the upper slopes of Mohammadabad-e-Chahak playa, in order to reduce runoff entrance and thereby control the playa extension. Seeds of Haloxylon persicum and Atriplex canescence have also been sown inside the pits. This research was aimed to investigate effects of ...
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Curved pits have been constructed in the upper slopes of Mohammadabad-e-Chahak playa, in order to reduce runoff entrance and thereby control the playa extension. Seeds of Haloxylon persicum and Atriplex canescence have also been sown inside the pits. This research was aimed to investigate effects of pit size and pit zones on establishment rates of the cultivated or naturally growing plants. Along the line transects, 30 pits were created within the streams and 30 in flat areas. A hypothetical pit was also considered close to each pit, with the same dimensions. The number of cultivated and naturally growing plants was counted in five different zones within each pit. Plant establishment was higher for the pits created inside the streams as compared to the flat areas. The number of established A. canescence and naturally growing plants was increased by increasing the size of curved pits, however it did not affect the establishment of H. persicum seedlings. The cultivated plants showed the highest establishment in the middle of the ridge; but the highest number of naturally growing plant was found in the center of pits. The percentage of pit destruction was increased by increasing their size, nevertheless the number of broken pits was low (15%). Accordingly, we suggest, creating pits inside the streams, rather than flat areas, small pits (6-8 m2) for H. persicum but large pits (10-12 m2) for A. canescence.
Fahimeh Rafiee; Mohammad Jangjou; Hamid Ejehadi
Volume 22, Issue 1 , June 2015, , Pages 73-85
Abstract
Plant traits can be used to study the mechanism of vegetation responses to the environmental disturbances. This study was aimed to study the changes in plant traits, in six-and two- year periods after wildfires in a semiarid rangeland. Three adjacent sites (control, burnt at 2004, burnt at 2008) were ...
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Plant traits can be used to study the mechanism of vegetation responses to the environmental disturbances. This study was aimed to study the changes in plant traits, in six-and two- year periods after wildfires in a semiarid rangeland. Three adjacent sites (control, burnt at 2004, burnt at 2008) were selected in Jowzak rangelands, Northern Khorasan, Iran. Plant sampling was conducted at spring and summer 2010. Floristic list was recorded in each site; also, 58 morphological, phonological and reproductive plant traits were measured. Results indicated four different responses by plant traits to the chronological wildfires. Type1 no response; 37 traits were not affected by the wildfires. Type2 adapted traits: annual plants were increased by times after burning. Type3 tolerant traits: plant with spins, hairs, prostrate canopy, rosette and elongated leaves, ramified stems, scattering by seeds, reproduction by seeds and/or rhizomes, and leaf phenology more than three months initially increased but finally reduced. Type 4 sensitive traits; perennial grasses, shrubs, scopus canopy, non-spiny, succulent leaves and stem elongated leaves gradually decreased with times after burning. In conclusion, plant traits have important roles in determining the responses of plant species to the environmental disturbances; hence, they can affect the secondary succession after the wildfire in rangelands.
Sepedeh Anvarkhah; Mohammad Khaje hoseini; Mohammad Jangju
Volume 18, Issue 1 , May 2011, , Pages 71-89
Abstract
Seed dispersal distances of mother plant is a basic aspect in plant life history, and have great effects on plant ecology, evolution and conservation. Seed dispersal modes of species can often be recognized by morphological characteristics of fruits and seeds. A laboratory experiment was conducted ...
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Seed dispersal distances of mother plant is a basic aspect in plant life history, and have great effects on plant ecology, evolution and conservation. Seed dispersal modes of species can often be recognized by morphological characteristics of fruits and seeds. A laboratory experiment was conducted on seeds of 24 Northern Khorasan rangeland species during 2008. The size of seeds was measured by digital caliper with a precision of .0.01 mm (operating instruction in resolution 0.01 mm), and the seeds' shape were observed by binocular and drown by hand in scale of 30-80 times. Seeds were categorized in five categories based on their shapes and morphological traits namely, Nutrient Containing Structure (i.e. Artemisia seiber), Balloon Structure (i.e. Agropyron trichophorum),Elongated Appendages (ie. Salsola arbusculaformis), No Appendages (i.e. Stachys inflate and Iris songarica) and other Specializations (i.e. Kochia prostrate). According to the results, balloon structure category was identified as the most common seed dispersal mode in the zone of Northern Khorasan (with 9 species) which let the wind disperses the seeds easily. The elongated appendages category was placed in the next group and other categories owned third place. It can be concluded that balloon structure has provided the most suitable dispersal system for the seeds studied in Northern Khorasan rangeland