جستجوی مقالات مرتبط با کلیدواژه "نهال کاری" در نشریات گروه "کشاورزی"

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.

Due to the proximity to the water supply canal (Karun to Mahshahr) called Kut-Amir Canal and the availability of suitable water for irrigating the seedlings, the cultivated area was irrigated by surface irrigation and Furrow. The purpose of this study is to evaluate the trend of vegetation changes in during four consecutive years (2018-2021) and in two seasons in seedling cultivation areas was investigated. A total of five 100-meter transects, each 50 meters apart, were systematically established in the three selected areas. Around 30 fixed plots were installed along transects. In the two growing seasons of spring and autumn, the coverage of native species was recorded. The Simpson and Shannon, dominance, uniformity, and diversity indices were estimated using the PAST software. The results of one-way analysis of variance for the spring of 2018 to 2021 showed that there is a significant difference between the mean indices of coverage percentage, dominance, uniformity, Simpson and Shannon and Ghana diversity indices in consecutive years of harvest. The results of the Wilcoxon test showed that the indexes of species number, Simpson, Shannon, Evennnes, Manhinink and Margalf increased in the second year compared to the first year. Also, due to the fact that the sig rate is less than 0.05, there is a significant difference between the dominance indices, Simpson index and Shannon during July 2020 compared to 2019, but between changes in coverage percentage in the two there was no significant difference for consecutive years. The results of Duncan test showed that there is a significant difference between vegetation percentage and dominance index, Simpson and Shannon in spring (2018 and 2019) compared to (2020 and 2021) and is in two separate categories. Take. From the above observations and results, it can be concluded that in general, Shannon and Simpson diversity indices in the last year (2021) compared to the beginning year (2018) have increased significantly and this change is the result of increasing the uniformity and species richness in the area has been. The best options for improving the desert area above are Seidlitzia rosmarinus and Tamarix passerinoides. Also, the construction of Furrow along with seedling cultivation holes causes the accumulation of rainwater and the gradual emergence of other native species.

Wind erosion is a serious problem in many parts of the world, especially in arid and semi-arid regions and it is an important factor in soil degradation and loss. In most area, conservation operations against the wind erosion are appropriate practices.There are two main strategies to combat wind erosion. These first strategy is to increase the strength of erodible bed against erosive factorsand second one is to reduce the force of erosive factors. Seedling is the more effective solution to reduce speed of wind, to combat wind erosion and to stabilize the drifting sands. Therefore, the objective of this research was to study the effect of mechanical and biological management practices on the amount of wind sediment in Tal-Hamid area, which is located in Tabas (Khorasan Razavi province, Iran).

In order to determine the role of each management practices on wind erosion and its control, sediment traps were established at different distance between conservational practices at 0.5, 1 and 1.5 meters from the surface of the earth. Conservational treatments included T1 (4 rows seedlings of Haloxylon persicum and 3 rows native plant of Stipagrostis) T2 (fence and sand channel), T3 (one row of Hammada Salicornica, 3 rows seedlings of Haloxylon persicum, and one row Stipagrostis), and T4 (moat and Railroad tie). Also, a control sediment trap was regarded in adjacent area without any conservational practices. The management practices had been performed for 3 years. After then sediment traps were established in December 2015, and according to wheatear information, after each wind storm (two times in each month) the trapped sediments were collected and weighted in established sediment traps for each treatments from January to June 2016 (spring and winter seasons).

The results showed that all conservational practices were effective to reduce amount of sediment and the effect of T1 and T2 in reduction the wind sediment was considerably greater than other treatments. The more reduction of sediment load was found at height less than 0.5 m, therefore it can be concluded that the biological and mechanical practices could considerably prevent the saltation movement of sand particles. The wind sediment during the spring (due to lower moisture content and greater wind speed) was more than the winter. In addition, among the conservational treatments, the lowest value of wind sediments was related to mechanical management practices (fence and channel) and the highest amount of wind sediments was related to biological management practices (four rows of Haloxylon, and native plant i.e. Stipagrostis) in both seasons, because T4 and T3 are the first hedges against wind direction and they are located behind T2, and considerably have decreased the speed of wind, therefore when low speed wind reach to T2 its speed and energy is low. As a result of this, the sediment load In T2 was the lowest.

In general, biological and mechanical management practices decreased considerably the amount of wind sediment compared to the control. In spite of common viewpoint, the biological management practices may decrease the wind erosion, but due to unsuitable growth of Haloxylon seedlings and plants as a result of drought duration and deficiency of water, their efficiency in reduction of wind speed and energy especially T1 and T3 was not more than mechanical management practices (T2). It seems that during 3 years Haloxylon seedlings have not been grown sufficiently, and if they grow for long time, they can decrease the wind erosion considerably. According to results of this research, application both simultaneous biological and mechanical practices are needed to control wind erosion in arid regions such as Tabas.