جستجوی مقالات مرتبط با کلیدواژه « plant establishment » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

The distribution and establishment of plant species are influenced by various environmental conditions. Calligonum bungei, a species of the genus Calligonum, is widely distributed in arid and semi-arid climates in Iran. This research aimed to investigate the environmental conditions governing the distribution of Calligonum bungei in the desert rangelands of Kerman province. The study focused on identifying different types of Calligonum bungei habitats, assessing canopy cover, density, and associated species, and examining the influence of environmental factors, such as climate, topography, and soil, on the species' distribution.

Four representative areas in Kerman province were selected to represent the dominant types of Calligonum bungei habitats. Geomorphological types were identified using satellite images and field visits. Environmental factors, including climate, topography, soil properties, and characteristics specific to the species (density, canopy cover, associated species), were evaluated in each habitat type. Vegetation studies were conducted along 300-meter transects, with plot sizes determined based on vegetation type and distribution (100 square meters). A total of 40 plots (10 plots per studied area) were investigated. Canopy cover was determined by measuring two perpendicular diameters of the plant canopy. Principal component analysis (PCA) using PC-ORD software was employed to analyze the relationship between environmental factors and species establishment in the study areas.

The results showed that Calligonum bungei was present in the altitude range of 1400-1750 meters, slopes ranging from 1% to 18.4%, and in all directions. The average annual rainfall in the areas varied from 55.5 to 163.4 mm, while the average annual temperature ranged from 16.7 to 26.4 degrees Celsius. The minimum and maximum absolute temperatures recorded were between -20.8 and 48.8 degrees Celsius, respectively. The average annual humidity ranged from 29.6% to 42.5%, and the length of the dry season varied from 8 to 12 months per year. Soil analysis revealed shallow soil with sandy-loamy to sandy-loamy texture, sand content between 67% and 84%, lime content between 8.5% and 20%, carbon content between 0.1% and 1.35%, nitrogen content between 0.0% and 0.7%, absorbable phosphorus between 9.5 and 13.5 milliequivalents, absorbable potassium between 200 and 217.5 milliequivalents, salinity between 0.36 and 1.02 decisimians, and pH values between 7.8 and 8.09. In terms of vegetation, Calligonum bungei was observed to be scattered in all studied areas, with densities ranging from 10 to 280 plants per hectare and canopy cover varying from 0.1% to 5.7%.

The principal component analysis revealed that the first component (annual temperature, humidity, sand, and silt) explained 46.9% of the variation, the second component (altitude, slope, annual rainfall, phosphorus, lime, and potassium) explained 35.3%, and the third component (clay, nitrogen, and salinity) explained 17.8%. Environmental factors influencing the establishment of Calligonum bungei varied among the studied areas. In Anar and Kerman regions, increasing sand content and decreasing annual temperature, humidity, and silt were significant factors. In the Bam region, increasing phosphorus and potassium content and decreasing altitude, slope, annual rainfall, and lime were influential. In the Jiroft region, reducing sand content and increasing annual temperature, humidity, and silt played a role. Overall, these findings indicate that the identified environmental factors act as limiting factors for the establishment of Calligonum bungei in the study areas.

 Although man-made biochars positively affect soil properties and plant performance, their preparation and use, especially on a large scale, are costly. On the other hand, mineral biochar can be considered an alternative method. However, there is no information about the effect of this type of biochar and its method of use on soil characteristics and plant performance.

 Effect of levels of 0 (control), 5, 12, and 25% of mineral biochar (obtained from the mine of Koohbanan city, Kerman province) in three forms of use (including mixed with surface soil, mixed with deep bottom soil, and mixed with total volume soil) on the vegetative performance of bush Fortuynia bungei, shrub Calligonum comosum and tree Ziziphus spina-christi were evaluated in a completely randomized factorial design in the nursery during four months. Cultivation operations in two stages included the germination section (without biochar) and studying the treatments' effects on the species' vegetative characteristics. The seeds were planted in pots containing 100 grams of sand. After sprouting the seedlings and their three to five leaves, one seedling was selected from each pot and transferred to larger pots containing biochar. The amount of water required was determined based on the measurement of soil field capacity. Seedling characteristics were measured at 20-day intervals for four months, and biomass production was measured at the end of the experimental period. At the end of the test period, some soil properties were examined, including organic carbon, total nitrogen, absorbable phosphorus, absorbable potassium, acidity, and electrical conductivity.

 The application of different levels and the manner of using biochar to the evaluated characteristics showed that the most noticeable effect was related to the level of biochar. In other words, although using biochar or the cultivated species resulted in varying results, the amount of biochar had the greatest effect on the evaluated characteristics. The findings showed the effect of higher levels of biochar and the mixture of biochar with the total soil volume on plant species performance (Sig.0.005). Also, the species performed differently, so C. comosum had the highest growth height (65 cm), and F. bungei had the lowest growth height (19 cm). The method of using biochar also had a significant effect on plant biomass, so the highest biomass was related to F. bungei (9.2 grams) under the influence of 25% biochar mixed with the entire soil profile. The levels of biochar or plant species alone affected soil properties. However, the combined effect of the species and the level of biochar used on soil properties was not noticeable. With the application of 25% of biochar, nitrogen (from 0.14 to 0.25%), organic matter (0.88 to 4.1%), and electrical conductivity (0.76 to 1.33 dS/m) showed the most changes (Sig.<0.001).

 By increasing biochar levels, improved soil properties and plant performance were observed. On the other hand, biochar application affects plant performance depending on species. The method of using biochar also significantly changed the performance of cultivated plants so that, considering the economic discussion of using biochar, its mixture with the entire soil profile leads to higher production than mixing biochar with surface or deep soil. However, more studies are needed regarding biochar's effect on soil properties and plant performance.

Astragalus spp. are valuable in forage production, soil protection, etc. To evaluate the establishment and growth of herbaceous milkvetch, 10 genotypes, belonging to five species, including Astragalus vegetus. As.brevidens, As. brachyodontus, As. effusus and As. Cyclophyllus, were studied in Sanandaj in a randomized complete block design with three replications. Seed sowing was done in November 2018, and traits of plant establishment percentage, vigor, height and diameter of plant crown, number of branches per plant, average fresh and dry weight of the plant, and the ratio of dry to wet weight of the plant in 2019 and 2020 years was measured. According to the combined analysis of variance, the effects of genotype and year for all studied traits and the interaction of year × genotype were significant (p≤0.01) except for the percentage of establishment and the plant vigor for other traits. Results showed that seed germination, probably caused by seed dormancy or a stress tolerance mechanism, was gradual. In 2020, the mean of plant establishment was about 37%, the number of primary branches was 7.3, plant height and crown diameters were 35.2 and 35.9 cm, respectively, plant fresh and dry weight were 68.2 and 39.1g, and the dry to fresh weight ratio was 0.58. Results of principal component analysis (PCA) showed that two main components (PC1 and PC2) determined 80% of total variance and genotypes with high forage yield located in the third zone of bi-plot with a negative value of PC1 and mainly positive for PC2. In addition, the accession of As. effusus (West Azerbaijan) and three accessions of As. vegetus (Qazvin, Kurdistan and West Azerbaijan) in terms of adaptation and forage production are introduced as high forage yield and adaptable ones for rehabilitation of rangelands in Kurdistan and similar areas in the country.