IRANIAN JOURNAL OF NATURAL RESOURCES
Year:2001 | Volume:54 | Issue:1|Papers Count:8

In order to quantitatively assess desertification in Aghqalla and Gomishan plain and to present a regional model, a study was carried out in an area of 1720 Sq. Kms. In this study, after reviewing the existing methods, information collection and determining the study units (based on geomorphological facies) a model was suggested and evaluated. In this model three aspects of desertification namely current status, potential and total hazard were quantitatively studied. The study units were then mapped into 5 classes. In current status, desertification processes including water logging, salinization, degradation of plant resources as well as soil erosion were taken into consideration, and in potential hazard, desertification factors including climate and geomorphology (natural factors) and excessive exploitation together with improper structures (anthropogenic factors) were studied. Finally, through a combination of these two aspects, total hazard was determined.

This study was carried out in northern forests of Iran near Sari. The forestry management system here is the selection system. In this research, damages to the remaining forest stand were compared in two mechanized logging systems, the cable and the skidding system. The results indicate, damages on remaining forest stand in the skidding system are significantly higher than in the cable system. The factors determined in both logging systems were depth, size, and place of wound.

Jajrood is a permanent stream with physical and chemical properties appropriate for cold water fishes. Significant populations of different species of fish were identified in the stream (Refer to table 1 for scientific names). Members of Salmonidae and Cyprinidae (Particularly Capoeta sp.) constituted the important fish fauna.Permanent now of water, different agricultural fields around, diversity of trees and shrubs along the river together with an abundance of insects provide an excellent habitat for bird funa. About 80 species of birds were identified in dependence with the river. Some bird species are aquatic, some depending on the margins of the river while others live on trees and shrubs.Fifteen species of mammals are living along the river. Some, such as otter (Lutra lutra) are completely dependent upon water, while some such as wild bard Jackals, although terrestrial, but are ecologically dependent on the aquatic environment.Amphibians possess the lowest number of species. Population abundance of two species, Rana ridibunda and bufo viridis, depends on local conditions. Aquatic vegetation of the river system were collected and I identified (label 4).

in vitro plants are grown in an artificial environment, this leading to the development of a number of physilological characteristics. In This experiment the growth and photosynthetic performance of wild cherry (Prunusavium) cultured under different growth conditions, both in vitro and ex vitro (after 2 and 4 weeks)were investigated. Maximum photosynthetic rate (Pm) for in vitro plantlets was 1.3 micromol. CO2 m-2 s-1. Pm increased approximately 4 fold, two weeks after being transferred into ex vitro, as compared to originally ex vitro plantlets. In this experiment leaf biomass accumulation and leaf area in vitro were lower, as consistent with Pm. No relations were found between Pm, leaf chlorophyll (a+b) content, and a:b ratio. Both a low Rubiscoactivity and a reduced electron transport capacity of in vitro plantlets underlie the low Pm. Since the leaf nitrogen concentration of in vitro plantlets was significantly higher than that of plantlets grown ex vitro it canbe assumed that Rubisco activity rather than amount of this enzyme limits the Pm of in vitro plantlets.

Growth in industry creates environmental problems. This has been an important subject of debate during recent decades. At present, a consideration of polluting agents and conducting research on them, are among important issues.Leakage of water borne preservatives out of impregnated wood, unavoidable in the process of bleaching, contributes to pollution. In order to minimize leaching processes, preservative salts ought to be fixed in wood. In this study, fixation rates of ACC (Acid Copper Chromate) in oak sap and heartwood were compared at 17, 27 and 50°C temperatures. The required 6 cm thick specimens were made out of oak.In order to' get free preservative solution from sample, the sample was squeezed, the resulted extract being analyzed to determine concentration of active agents such as Cr6+, total Cr and Cu. Extracting was continued until the concentration of these materials was lowered to a minimum of their level, which would indicate full fixation (99.98 percent of Cr6+).The results indicated the positive effect of temperature on rate of fixation. At higher temeratures fixation rate was more considerable. Amount of Cr6+ in extract lowered with higher fixation rate and that was more pronounced in heartwood as compared with the sap. Fixation time at 50°C temperature was 134 hours for sapwood (6 days) while for heartwood it was 284 hours (12 days).Under conditions of 27 degrees, measured time was 858 hrs (36 days) for sapwood and 1022 hrs (43 days) for heartwood. Under conditions of 17 degrees, rate of fixation was found 10 be very slow (about 2877 hours or approximately 4 months). Cr fixation reached 99.97% but Cu and Cr were still measurable in extracts.

In this research a number of five formulae for production of cold marinade from roach (Rutilus rutilus) were investigated. The samples were stored in a domestic refrigerator at 6±2°C for a period of sixty days. Then during these sixty days, and according to a time schedule, the samples were tested for changes in their organoleptic properties, pH, peroxide value, total volatile base and total count of bacteria. The results indicate that after two days the pH in all samples dropped to less than 4.1. On the other hand changes in peroxide value were between 1.1 and 6.6 milliequivalents/1000 g, whereas total volatile base for the samples was 4.5 mg/100g, not showing any change. The total count of bacteria for most of the samples was negative. According to the taste panel, two of the formulae scored a high degree of acceptance and the rest as medium for their organoleptic properties.

Short term changes (5 years) of water infiltration in a clay soil were studied under protection from grazing vs. grazed conditions. Infiltration experiments, using rainfall simulating infiltrameter (Meeuwig, modified form) inside and outside 8 randomly selected exclusures from among 96, were conducted. Infiltration depth indices were measured on experimental plots during 1988. On the basis of Kostiakov equation, regression analysis on collected data was performed equation coefficients for instantaneous, cumulative, and hnal infiltration rates, being computed. The results indicated that instantaneous and final infiltration rates had increased in protected areas, in grazed as well as in two sites outside exclusures No. 65 and 41. Increasing instantaneous and final infiltration rates in grazed sites on vegetation type 4 (fig.1), was due to crust breaking through trampling, increased density of annual grasses, annual and perennial forbs as well as more rocks and pavement cover. Increased infiltration rate in grazed site on vegetation type 6 (fig.1) was mainly related to grazing protection by rural community during the experimental years. Comparing to protected site in this site canopy cover of perennial forbs increased inside exclusure. On the average, final infiltration rate in 8 vegetation types under protection from grazing increased 54.1 percent (2.09 cm/hr). Correlation coefficients between final infiltration rate, canopy cover and litter were 0.70 and 0.67 respectively (%5 significant level).