|
|
:
|
Fire with change in structure and composition vegetation has important effects on natural ecosystems function. The aim of this study was to investigate the effect of fire on production, density and surface cover of plant species, vegetative forms and palatability classes of rangeland plants. For this purpose, in the growing seasons of 2018, 2019 and 2021 in each of the control and fire areas, 4 transects of 200 meters with a distance of 100 meters were considered and 10 fixed plots were installed on each transect. Inside each plot, all vegetation indices were evaluated. Then, in order to investigate the effect of fire on different factors, analysis of variance and comparison of means were performed using independent T-test and one-way ANOVA tests in SPSS software. The general comparison of control and treatment areas shows that there is a significant difference means between control and fire treatments in all sites at the level of 1%. The data from this study, especially in species with predominance of wood species, showed that plants that avoid lethal temperatures are more than those that can they tolerated temperatures. Considering the ownership and management conditions of Iranian rangelands, the results of the present study and ten-year monitoring of rangelands burned by the author in the form of various projects show that fire is not accidentally and inadvertently desirable rangeland management, but forecasting and planning before and after along with why management is important. In other words, any fire in the pastures will not lead to the improvement of the structure and composition of ecosystem species and increase the quality of forage. In pastures dominated by woody plants with limited grazing, fire causes significant reduction and extinction of woody and thorny species and their replacement by newly grown plants, which are mainly annual species. In fact, the growth of palatability plants after fire in these areas increases and attracts the attention of livestock and as a result, the pressure of grazing livestock from adjacent areas to fire areas. Of course, the opposite is also true in summer grasslands and pastures, which are often covered with palatability plants. Fire can increase the density of perennial grasses and forbs and reduce the density of trees and shrubs in the short term. Examination of the survival rate of vegetative forms also showed that grasses have the highest rate of regeneration of burned rootstocks after fire and shrubs have the lowest rate of survival after fire. Perennial forbs also have a relatively high survival rate in the regrowth of burnt plants after a fire. The effect of fire on the condition of the rangeland indicates that at least in the short term it can reduce the condition of the rangeland to lower levels due to the decrease in the percentage of canopy cover and the increase of bare soil. Also, the study of pasture condition trend showed that in the study areas, the control areas are more stable than the fire area. Fire at least in the short term increases the sensitivity of soil and vegetation. In this study, it was found that in all types there are resistant species that have more stability than other species that can be used in critical areas. In general, considering ecological and managerial considerations, controlled fire can be used as a factor for better access of livestock to fodder and increase of palatable plants in shrub lands and proposed it as a breeding method with management measures in Iran only in different rangeland ecosystems such as shrub lands. In summer grasslands, fires have had catastrophic effects on key species on the site in the short term. Although the situation of the rangeland has been reduced from the upper class in the control to the middle class in the field of fire, but in general, the situation of the situation in this site has not changed. However, its details are remarkable. That fire has completely changed the vegetative type and as a result, the production, density and canopy cover of different food classes and different vegetative forms have also undergone fundamental changes. So that the plant composition gets a score of 10 in the control and a score of 2 in the field of fire, which shows that the quality of the plant composition has regressed. But few figures in this discussion do not cover qualitative changes. Therefore, it seems that the position and tendency are not suitable parameters to determine the effect of fire and should be considered in more detail, which is a theory in itself. These changes may not be significant in quantity, but we observe changes in quality that cannot be accurately calculated by conventional methods and their effectiveness. The other hand, although the amount of production in the field of fire is higher than the control, but does not necessarily lead to an increase in the allowable amount of forage that can be harvested. The scientific and logical reason for this can be related to the distribution of total production in different forage classes and the allocation of harvest coefficients of each class when calculating the allowable amount of harvestable forage. Therefore, the study of the effect of fire on plant species and its consequences in different rangeland habitats has research value and based on the results, we can comment on its implementation as a way to improve rangelands in different ecological areas.
|