Aezam Khosravi Mashizi; Gholamali Heshmati; Najmeh Faryabi
Volume 21, Issue 4 , March 2015, , Pages 571-579
Abstract
Negative and positive interactions among plants have important role for species coexistence and community diversity. The strength and direction of the interaction effect may change with environmental disturbances such as grazing and fire. This study was aimed to evaluate the effects of environmental ...
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Negative and positive interactions among plants have important role for species coexistence and community diversity. The strength and direction of the interaction effect may change with environmental disturbances such as grazing and fire. This study was aimed to evaluate the effects of environmental disturbances such as fire and grazing on interactions between shrubs and herbs in rangelands of Goghar Bafte. Hence, beneath 20 dominant species of Artemisia aucheri and 20 open patches, a quadrate of 20 cm×20 cm was plotted and the variation in the biomass, richness and vegetation cover of herbs were measured in regions under exclosure, fire and grazing. Results showed that biomass and vegetation cover of herbs were increased by shrub presence because of positive interaction between shrubs and herbs inside exclosure. Although the facility of shrubs was reduced by grazing and fire, its rate was not equal in both places. Under grazing, interaction between shrubs and herbs remained positive but shrubs were severely damaged by fire and the interaction between species altered from positive to negative. The overall conclusion is that fire plays a more important role in changing the interaction between shrubs and herbs.
Aezam Khosravi Mashizi; Najmeh Faryabi; Nematollah Maddadi Zadeh
Volume 21, Issue 1 , June 2014, , Pages 75-82
Abstract
To study the role of shrubs refuge for annual plant inside and outside exclosure, in Goghar, Bafte, quadrates of 20cm×20 cm were plotted beneath 20 species of Artemisia aucheri, Astragalus gosipinus and 20 open patches, then the name and number of annual species were recorded in quadrates. Species ...
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To study the role of shrubs refuge for annual plant inside and outside exclosure, in Goghar, Bafte, quadrates of 20cm×20 cm were plotted beneath 20 species of Artemisia aucheri, Astragalus gosipinus and 20 open patches, then the name and number of annual species were recorded in quadrates. Species responses to grazing and shrubs were analyzed by two-way ANOVA and Post-Hoccomparisons. Results showed that shrubs acted as biotic refuges by protecting 7 species of 22 annual species against direct grazing. Although these seven species are palatable plants but Artemisia aucheri and Astragalus gosipinus that are less palatable in growing season of annual plants can have refuge role for palatable annual plants in grazed plant communities. Some annual species that were rather abundant under the shrubs were rarely found in the open patches in both the grazed and ungrazed quadrates. These species were most probably facilitated by the shrubs. Consequently, shrubs have important implications for diversity, conservation, and management in grazed ecosystems because of their facilities and roles as refuge.
Nematollah Madadi Zadeh; Hossein Arzani; Ghavaloddin ahedi; Najmeh Faryabi
Volume 21, Issue 1 , June 2014, , Pages 128-138
Abstract
In the current study, the effects of exclosure were examined on rangeland vegetation at two study sites including, reference site (inside the exlosure) and critical site (outside the exclosure). Research was conducted by the systematic-random method and 160 2*1.5 m plots were established. Inside each ...
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In the current study, the effects of exclosure were examined on rangeland vegetation at two study sites including, reference site (inside the exlosure) and critical site (outside the exclosure). Research was conducted by the systematic-random method and 160 2*1.5 m plots were established. Inside each plot, the percentage of canopy cover, litter, gravel and bare soil as well as density of class I, II, and III species were recorded. Dry matter yield was also calculated. Four-factor method and trend balance method were applied to determine the range condition and range trend, respectively. According to the obtained results, due to the exclosure, litter, yield, canopy cover percentage and class I species composition increased up to 24.72%, 37.42%, 23.6%, and 80.6%, respectively. On the other hand, the percentage of bare soil, gravel, and class III species composition decreased to 34.29%, 17.16%, and 26.96%, respectively. Mean differences in all parameters inside and outside the exclosure were significant at both study sites. Our results also indicated that exclosure led to the improvement of range condition and range trend.
Najmeh Faryabi; Mansour Mesdaghi; Gholam ali Heshmati; Nemat alah Madadi Zadeh
Volume 19, Issue 3 , December 2012, , Pages 421-431
Abstract
Knowledge on floristic composition is one of the most important factors in management of rangeland utilization. Improper utilization of rangelands and lack of attention to the ecological potential of range habitats is the main reason for rangeland degradation. In this study, floristic composition and ...
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Knowledge on floristic composition is one of the most important factors in management of rangeland utilization. Improper utilization of rangelands and lack of attention to the ecological potential of range habitats is the main reason for rangeland degradation. In this study, floristic composition and canopy cover of the species of reference area (exclosure), key area (with mid grazing) and critical area (with over grazing) were considered and three areas were compared together. Ranking of the canopy cover percentage was performed through Van-der-Maarel
method and counting the number of the species was carried out using a systematic-random method. According to the obtained results, three relations were obtained as follows: Major biological forms: Therophyte> Hemicriptophyt> Chamophyte> Geophyte> Phanerophyte; Dominant growth form: Herb> shrub> grass> tree; Vegetation ranking based on canopy coverer: reference> key> critical area. In the critical area, due to over grazing and out of grazing season, canopy cover was strongly reduced and plant palatability decreased.