جستجوی مقالات مرتبط با کلیدواژه "نهال کاری" در نشریات گروه "آبخیزداری، بیابان، محیط زیست، مرتع"

The phenomenon of desertification has always been considered as one of the most important challenges facing Iran, which has been aggravated by human and climatic factors in recent years. Therefore, it is necessary to implement anti-desertification plans and projects set through the Development planning to curb desertification and restore and improve degraded lands. In this regard, the severity of the phenomenon can be decreased by applying appropriate management solutions and methods and preventing its expansion and progress. Implementing anti-desertification management and rehabilitation projects according to the ecological conditions of each region improves the condition of the vegetation, strengthens the soil stability, and protects the soil from the risks of water and wind erosion. Therefore, analyzing different aspects of the anti-desertification projects which are planned and carried out by the government is required for improving management in the natural resources sector. One such measure can be the restoration of desert pastures with regard to unfavorable climatic conditions. Thus, this study set out to investigate the influence of anti-desertification management and restoration projects in improving soil stability indicators and vegetation characteristics.

This study was conducted in four sites located in the Yazd-Ardakan plain, including the seedling site, the water weed management site, the mulched site, and the enclosure site. The main species investigated in each of these sites was Haloxylon aphyllum. To this end, four transects were placed in the site at regular intervals. It should be noted that the transects were placed parallel and perpendicular to each other in flat and sloping areas, respectively. The number of plots on each transect was 15 and the area of the plots was 210 cm. Moreover, the index Plant characteristics such as canopy percentage, density, reproduction, and freshness of Haloxylon aphyllum species were measured. Finally, after collecting the required data, statistical analysis was performed using the SPSS software.

  According to the results of statistical analysis performed via independent t-test, a statistically significant difference was found in the percentage of vegetation and density at the error level of 1% in all investigated sites. Duncan's multiple range test revealed significant differences in mean values among treatments. The treatment associated with herbaz exhibited the highest mean values for vegetation cover (72.5%), plant density (75.4), regeneration (542.0), and vigor (33.61). Conversely, the treatment subjected to enclosure showed the lowest mean values for vegetation cover (68.1%), plant density (2.0), regeneration (111.0), and vigor (24.12).

Compared to the control area, the percentage of vegetation and density of the effective area was significant in the seedling site (where the seedling project is based on seedling irrigation), which is due to the lack of suitable conditions and rainfall in the seed establishment. The wastewater management site demonstrated increased vegetation cover and density due to enhanced water infiltration and readily available moisture, which facilitated plant establishment and growth. Similarly, the mulched site exhibited higher vegetation cover and density compared to the control, attributable to the creation of a subsurface moisture layer beneath the mulch, providing a favorable environment for seed germination and plant development In the enclosure site which is less affected by human changes, the amount of soil erosion and ecosystem destruction is lower than other sites in all dimensions, leading to the higher percentage of vegetation and plant density. The establishment and expansion of vegetation cover through various methods have been implemented in recent decades as a means to combat desertification and mitigate the damages caused by dust storms in arid regions. However, water scarcity poses a significant constraint. Consequently, it is recommended that, in the context of desertification management and rehabilitation projects in the Yazd-Ardakan plain, the most effective approaches be prioritized as follows: runoff water management, mulching, afforestation, and enclosure.

Watershed management is one of the most efficient methods of sustainable land management. In the current research, was evaluated the economic and social effectiveness of implementing watershed projects in the Gelevard sub-basin, Nekarud watershed, Neka city. The statistical population of this research included 2775 households and the sample size was 280 household heads. Data analysis was conducted using SPSS software. The results showed that the effectiveness of watershed management measures in preventing the reduction of flood damage and the level of satisfaction with the mechanical and biomechanical operations implemented in the study area have the highest priorities in terms of average rank. Correlation coefficients (R2= 0.60, P-value= 0.01) examination showed a high correlation between the implementation of watershed management operations and creating incentives for the residents of the village to stay in the village and reducing migration from the village. The results of the Kruskal-Wallis test showed no significant difference (Chi-square-1.32, P-value=0.72) between the effect of watershed management activities on improving people's living conditions in relation to the way of participation and the type of participation of the respondents in executive measures. Summarizing the results of this research showed that watershed management activities in this watershed improved people’s living conditions, increased the motivation of village residents to stay in the village, and reduced migration.

Measuring the diversity and identifying plant vegetation traits and functional groups and classifying them, in addition to helping to accurately identify the vegetative capacity of the area, helps us to understand the vegetation response of the area to disturbances and presence. Potentially resistant species with similar or invasive traits help. The purpose of this study was to investigate and evaluate the vegetative status of the region, the trend of changes and evaluation of the second sequence of dust centers in Khuzestan after planting seedlings in different ways. Functional groups (PFTs) were used. To evaluate the changes in the vegetation of the area by field survey, 15 transects of 100 meters with distances of 50 meters were systematically randomly selected (the first transect was randomly selected and the rest with a defined distance of 50 meters). Due to the uniformity of plant species composition and the absence of environmental effects, a total of 180 fixed plots with dimensions of 1 square meter (location recording with GPS device) were installed. The results of a recent study in three areas of the dust center in the southeast of Ahvaz showed that in selected areas, various irrigation methods along with rainfall will cause significant changes in the percentage of cover (frequency) and the number of species from 2017 to 2020. Functional groups in the Tovayel region with surface irrigation (Faro) In 2020, nine groups were identified, in Bagan region with tanker irrigation and hole digging with seven excavators, and in Hanitieh region with tanker irrigation and hole digging seven functional groups. The results of T-test analysis also showed that there is a significant difference between the average of the two values of all indicators, including the diversity of Shannon and Simpson in March 2017 and March 2020 for all three regions so diversity indicators raised since number of species and cover increased.

The study of vegetation and the measurement of diversity indices are suitable tools for studying the status of forests and rangelands and evaluating them. The purpose of this study is to evaluate the trend of vegetation changes during four consecutive years and in two seasons in the Bagan region. For this purpose, 5 transects of 100 meters with distances of 50 meters in the study area were considered systematically randomly. A total of 30 plots of one fixed square meter were installed along the transects. In two growing seasons, spring and fall, from 2017 to 2020, the type and percentage of cover of native species were harvested. Dominance, uniformity and diversity of Simpson, Shannon and Hill species were measured using PAST and R software. The results of one-way analysis of variance (ANOVA) showed that there is a significant difference between the mean of dominance, Shannon and Simpson indices, percentage of cover, and the number of species in the spring of different harvest years. In fall, except for the dominance index in other indices during July 2019 compared to 2018, there was a significant difference. From the results, it can be concluded that despite the return of some annual or short-lived species such as Bienertia cycloptera Bunge and Salsola jordanicola Eig. following irrigation of cultivated seedlings and rainfall, the study area is still sensitive and fragile and needs to be managed and confined until proper rehabilitation.

In this study the effects and costs of application of two kinds of super absorbent polymer on the establishment and surviving of seedlings was investigated. Experiments were done in the field and on two kind of soil with different salinity (EC: 4.5 and 8 dsm-1). The results showed: the establishment rate of seedling in control was about 40 percent. The percentage of seedling establishment in the hydrogel treatments significantly increased and statistically is equal to the optimal surviving of the seedling (80%). Soil salinity on seedling establishment in the same treatments did not produce significant differences. The results were compared with a similar project to determine the costs and benefits. Based on the results a 30 percent reduction in water usage per round and 33 to 50 percent reduction in the number of irrigation replicate were recorded. The costs in compare to the normal project varied from -2 to 29 percent respectively for treatment Herbosorb® 0.5% and Aquasorb 1%. The treatments Herbosorb® and Aquasorb with usage level of 0.5% caused about 2.5 percent for each one percent increasing in the cost. There is no significant increase in the percentage of seedling survival by using 1% super-absorbent compared to 0.5 percent.

All worldwide studies verifies global phenomenon of climate change caused by the greenhouse effect of carbon emissions on this planet. Carbon sequestration in terrestrial ecosystem is a sustainable approach, with no environmental risks. One of the key potential in carbon sequestration in our country is the watershed management biomechanical operations in the natural resources areas. This research was conducted to evaluate this operation options in north and middle parts of Zagros ecological zone in atmospheric carbon sequestration and to offer optimal options for these regions. For this purpose, in each of the provinces (Kermanshah, Lorestan, Kurdistan and Fars), one or more representative sites were selected. Then, soil, biomass and litter sampling were taken by field operations using systematic randomized method. Soil organic carbon and other soil physic-chemical properties and carbon stock of biomass and litter samples were determined in the laboratory. Then, carbon sequestration indices including soil, biomass, litter and total carbon sequestration, were measured per hectare. Analysis of the research results indicated that these operations are mainly planting of different trees along with flood and water spreading and bankets. Watershed management operations sequester up to 3.41 to 112.1 tons of carbon per hectare. Contribution of soil from total carbon sequestration was around 95 to 99 percent measured across different study site. Native terracing with tree planting of grapes (Vitis spp) and almond (Amygdalus spp) were the more efficient option in carbon sequestration along the selected areas.