جستجوی مقالات مرتبط با کلیدواژه "نهالستان جنگلی" در نشریات گروه "جنگلداری"

Paulownia fortunei is from industrial and multipurpose introduced tree species that has been considered for wood farming, agroforestry practices and seedling production in northern Iran, especially in Golestan province, due to its suitable growth properties and productive traits. Knowing the factors affecting the germination and early growth of this species can provide the possibility of improving the quality of seedlings produced in forest nurseries and thus increases the feasibility of success in planting practices of this species. Therefore, in terms of the importance of studying the reaction of P fortune against different light intensity control treatments, the present study tries to investigate the effect of artificial shading on the performance of this plant in the germination and seedling stages.

Thanks to the inherent differences in plant needs and responses in the stages of germination and early growth, in this study, two independent experiments were designed and performed to achieve the research objectives. Aimed to investigate the effects of artificial shading treatments on performance of this plant, two independent experiments were conducted at germination and seedling stages. In the first experiment, using a completely randomized design, seed germination features were studied under three shading (25%, 50% and 75%) and one control (without shade) treatments in the laboratory (Temperature of 25 °C and 70% relative humidity in a Germinator) conditions. In this experiment, seed germination was recorded for 3 weeks and at the end of the period, the growth traits of the sprouted seedlings were examined. Based on the information obtained, seed germination traits including germination speed (GS), germination energy (GE), peak value (PV), mean daily germination (MDG) and germination value (GV) as well as seed vigor index (VI) and length of shoot and root of sprouted seedlings were measured. In the second experiment, the growth and survival of 44 potted p fortunei seedlings under four treatments (including control, 25%, 50% and 75% shading) were studied in the first growing season for 5 months, from the beginning of July to the end of November. At the end of the growing season, all seedlings were taken out of the pot and length, diameter and dry weight of stem, leaf area and length, dry weight of main and secondary roots were measured after separating the shoot and root. One-way analysis of variance and Duncan's test were used for statistical comparing of treatments at 5% probability level.

The results showed that GP, GS, MDG, and VI did not affected by shading treatments, However, the negative effects of shading treatments, especially in 50% and 75% shading levels on GV and PV were significant. Artificial shading did not affect first year seedling survival, so that all of seedlings were survived under all treatments. Also, the results showed that under 50% and 75% shading treatments, stem length, stem diameter, stem dry weight, number and area of leaves were significantly higher than control and 25% treatments. Additionally, under 50% shading treatment, secondary root dry weight and total dry weight of seedlings were significantly upper than other treatments.

Seed germination and first year survival of P. fortunei did not so sensitive to light intensity, but controlling light intensity using artificial shading improve seedling quality traits of this species. Hence, use of 50% shading treatments can be proposed in nurseries of this species after initial stages of germination and seedling establishment.

Plant residue of forest nurseries is among the best available raw materials for producing compost to amend and strengthen forest nurseries soil. The size of raw materials has a major effect on shortening the time of composting as well as on increasing its quality. The mechanism, availability and working convenience with the threshers in different site conditions to convert plant residue into small pieces that are suitable for composting shows the suitability of threshers for such tasks. In this research, two kinds of knives with flat and sharp edges applicable to threshers were designed and applied to study the crushing quality of common plant residues. Treatments included pine cones, branches of deciduous, pine branches, coarse plants, herbs and pine needles. The performance of both flat and sharp edge knives were evaluated in a design with three repetitions. For most samples, the results showed that performance of the sharp knife exceeded that of flat knife. The crushing quality of different materials in different dimensions were significantly different at the α = 0.01 level. The time performance of sharp knife with an average mean 0.069290 kg per second was far better than flat knife with an average mean of 0.035661 kg per second. Sharp knife performed best for grinding pine cones with an average 0.01321 kg per second. Generally, more uniform and brittle plant residue can be crushed in a shorter time. Finally, the efficiency of threshers system with the designed knife is acceptable and suitable for the crushing of plant residue.

The aim of this study is to measure the technical and scale efficiencyes of forest nursery in Guilan, Mazandaran and gorgan Provinces using data envelopment analysis. In this study, data of 12 forest nursery during of 4 years (2010-2013) with two inputs (fixed costs and variable costs) and two outputs (number of plant production and revenue) was collected from General Office of Guilan natural resources, Shafaroud forest Company as well as Forest Rangeland and Watershed Managements Organization. CCR and BCC models were used in order to investigate the technical efficiency. DRS model was used in order to investigate the rate of return scale in efficiency. Results indicated that Shanderman, Jokandan, Peseson and Ghrogh nurserys was completely efficient (efficiency score were 1 or 100%). Furthermore, nurseries such as Kani, Safrabaste, pelambara, Shahr posht and Lakans had the lowest efficiency, respectively. This can be due to the nature of the input models and optimal management of nurseries in the input and output.