نشریه تحقیقات منابع طبیعی تجدید شونده
پیاپی 1 (پاییز 1389)

Determining the dimensions of shrub in Atriplex lentiformis plays a central role in soil preservation and forage accessibility in desert areas; hence, that end, a site approximitley 4.5 ha was selected and planted with the Atriplex lentiformis species in Siahkoh Kavir of Yazd province, in 1992. Treatments were arranged in a split splitplot, randomized complete block design. The row spaces (2,4 and 6 m) were main plot while durations of pruning (annual, biennial, triennial) were sub plot and heights of pruning (0, 20, 40, 60 cm and control) were sub-sub plot. The measurement of shrubs diameter and height in control treatment was initiated in the fall of 1993 and extended until 2001. The other treatments were measured in seventh and tenth years of studied period. Findings illustrated that the largest shrubs were attained in 4 m row spacing, triennial period and 60 cm height treatments. The diameter and height of mentioned shrubs were 226 and 181 cm and 178 and 146 cm at 7 and 10 years of age respectively. Providing the most efficient and accessible forage with maximizing its quality and quantity comprise the top priorities investigated in the current study.

Categorizing range suitability and evaluating rangelands hierarchically and based on their importance in order to rightly recognize their potential, particularly to fully exploit the arid and semi-arid lands which have a comparatively delicate ecosystem, can promote sustainable development. In order to investigate the rangeland suitability for goat grazing, this study analyses three sub-models, namely production model, water model (quantity, quality and distance) and erosion sensibility which also form the components of the final model. In the current study, FAO (1991) method, which is recommended for land capability evaluation, has been employed in Jamilabad – Baft province. Also, PSIAC procedure has been used to analyze erosion sensitivity. In order to determine water suitability of water resources, three factors quality, quantity and the distance from water resources were taken into account. On the other hand, to investigate the suitability of forage, factor namely standard exploitation, palatability, accessibility, physical condition of the rangefield are taken into consideration. The findings suggest that of all the rangefiels, 72.1% were marginally suitable (S3) whereas 27.9% of the rest of the rangeland were classified as N or unsuitable for goat grazing. It is worth noting that suitability classes of S1 and S2 were almost non-existent in the area under study. In total, limited availability of forage, soil erosion sensitivity were determining contributory factors to low suitability. Also, limited forage production together with soil erosion were recognized as limiting factors to rangefield types.

This study was conducted to evaluate the effect of dietary supplementation of protexin on the growth and survival of oscar (Astronotus ocellatus) fry with average weight of 4.99±0.12 g, in a sixty-days period. This experiment was conducted in a Completely Random Design in four treatments and three replicates with 144 fry (12 fry in each aquarium). Experimental Probiotic was mixed in three levels of 0.15, 0.5 and 1 gr/kg dry food and were fed to fry. The control treatment, was fed on nonsupplemented ration. Feeding rate was on basis of 4 percent of body weight, 3 times during a day. Based on the findings, all three experimental treatments showed a significant increase (p<0.05) in the final mean weight, weight gain percent and specific growth rate (SGR) as opposed to those of in the control treatment. Among all the experimental treatments, the treatment with 0.15 gr probiotic per kg of feed showed the greatest difference by accounting for the highest final mean weight (35.07±1.19), weight gain percent (615.67±15.04) and specific growth rate (SGR)(3.27±0.10). The best feed conversion rate (FCR)(1.13±0.04) and feed coefficient efficiency (FCE)(88.07±2.99) were obtained in the treatment of 0.15 gr probiotic per kg feed which was significantly different from that of in the control(p<0.05), whereas the treatments of 0.5 and 1 gr probiotic per kg feed did not have a significant difference compared to the control(p>0.05).Also, the maximum survival percent(100%) was obtained from the treatment of 0.15 gr probiotic per kg feed. The results indicated that the ability of probiotic protexin to influence the increase the growth rate and survival in oscar fry is relatively high and the most effective concentration is the level of 0.15 gr probiotic per kg of feed.

Arid & semi arid forests are complicated ecosystems which play an integral part by not only protecting soil and water and sequestrating carbon but also by producing byproducts and economically supporting the life of most inhabitants. Regrettably, the excessive and inefficient exploitation of such valuable resources namely by overgrazing, cutting top branches of trees, developing new dry farming places and cutting down trees for fuelwood have inflicted irreversible damage upon the vegetation cover and soil.Thus, exclosure is considered as one of the effective methods for improving the damaged plants. The current study aims to investigate the effects of the 15- year exclosure on the changes in the vegetation cover for Amygdalus forests studied in Sechah - Baft region. Here, the random systematic sampling method was applied ( the mesh with the dimensions 100m2 *100m2 ); for this reason, 50 plat (with the dimensions 20m2 *20 m2 ) for tree cover & 50 plat(with the dimensions 10m2 *10 m2 ) for understory cover in the exclosure area & the same numbers of plats with the above-mentioned specifications have been pitched in the nearby field. In the present study, the SPSS, which is a statistical software, has been used to compare the means. Similarly, in order to investigate the physical and chemical condition of the soil, some samples of the region under study (in exclosure & nearby) were selected so that characteristics of the soil, namely, structure, acidity, electric conductivity, organic substance, lime, plaster, potassium, sodium, calcium, sulfate & bicarbonate can be measured. Findings suggest that canopy covers of species, density and diversity of species (forest & understory) in the exclosure is more than those outside the exclosure. Also, the organic substance percentage and soil depth in exclosure- mananged region are more desirable, and the physical characteristics of soil have a significant impact on the changes in the vegetation cover of the region. (The fact that the soil nearby the exclosure was beaten due to cattle grazing made it difficult for seeds to be germinated). It is also worth noting that the exclosure led to an increase in the number of herbaceous species & A.scoparia in the region and as a result it can be considered as a leading method pioneered for pitching of vegetation.

Preference value of species can be useful for ranger to present practical solution for selecting suitable. Livestock according to kind of species and rangeland suitability. To achif this goal, investigation of preference value of species which was grazed by camel, was considered in Halvan Tabas region which is located in Yazd province. six native species of camels were randomly selected and their gazing time was observed and recorded. The data collection process involved sixty-minute observation of each camel recorded by chronometer in different seasons, one in the morning and another in the afternoon. The data were analyzed through split plot design, and the Duncan test was used for camper mean. The results indicate that the preference value of plants has significant difference (p<0. 01).The findings also suggest another significant difference as far as seasons and time of grazing ( i.e. morning or afternoon) are concerned. Based on the anlysis on the means of the percentage preference value of the species through out the year, the following were attained: the percentage of plant preference value was 48.4% for Haloxylon aphyllum (the first palatable species), 22.6% for Seidlitzia rosmarinus (the second palatable species), 18.78% for a collection of annual species (third palatable species), and 7.2% for Salsola arobuscula ( the forth palatable species). In fact, a significant difference was observed among species. There was no significant difference (p<0. 01) among other 4 species which are Calligonum persicum(1.1%), Stipagrostis pennata(1.1%), Astragalus squarrosus(0.7%) and Peganum harmala(0.01%). As regards the four seasons, The annual plants and Haloxylon aphyllum had the best palatability for camel grazing in spring and in summer until winter, recpectiving. In contrast, Peganum harmala had the least palatability in all phonological stages. Also, in total, the percentage of grazing time in the morning was more than that of in the afternoon. Furthermore, the percentage preference value of Haloxylon aphyllum and Seidlitzia rosmarinus were more in the morning and afternoon, respectively. Finally, no significant difference of any kind was observed among the other plants with regarding their preference value (p<0. 01).

Aquagerm is an antiseptic and mixed-oxidant disinfectant produced for the first time in Iran with the capability of being used for aquatics. The current study, which was undertaken in February 2009, aims to address the potential tissue Changes in rainbow trout (Oncorhynchus mykiss) if bathed in aquagerm as disinfectant. In this study, 40 fishes in natural and healthy conditions were picked from a fish farm in Mojen village - Shahrood city, 20 of them transferred into the treatment pond, while the others were moved to the control pond. 8 days later, the treatment group were bathed in 1/2000 aquagerm dozap for 45 minutes.Then through 0, 40, 24 and 48 hours. Section 5 sample from treatment group and 1 from control were caught in order to autopsy from kidney , liver and gills. Subsequently, the samples were fixed in 10% formalin. Samples were transferred to the laboratory of Tehran University. In the research lab, through standard methods of histology, 5-micron sectional samples were prepared for optical microscopy. Through microscopic analysis of liver, some evidences of increased melano-macrophage, glomerular shrinkage, and dilatation in Bowman capsules were observed though no tissue damage of any kind was observed in liver. As regards gill microscopy, symptoms such as inflation, detachment of basic layers in secondary gill filaments, aneurysm, appearance of clavate filaments, inflation and disorder in gill septum, shortened and thickened secondary gills, hyperplasic perichondrium, and epithelial lifting were observed. In general, such observed damages, which were in fact natural responses of studied organs to external materials, are not regarded as pathologic damages. All in all, it seems that the application of this specific disinfectant poses no imminent threat to the vital organs of the samples studied here.

In order to assess the viability and growth rate of twelve specific coniferous species planted in Arasbaran forests in 1996, Heresar and Kalaleh regions have been studied here. The species studied here are as follows: Pinus pinea, Cupressus sempervirens var. horisontalis, Pinus nigra var. austrica, Pinus eldarica,Cedrus atlantica, Cupressus arizonica, Pinus sylvestris, Picea abies, Pinus nigra var. pallasiana , Pinus nigra var. carmanica, Pinus brutia and Larix decidua. Statistical design of completely randomized block was employed in this study; that is, number of four replicates in Kalaleh altitudes and three replicates in Heresar with 36 individual saplings for each replicate were selected. All species were analyzed on the basis of height, collar diameter, viability percent, vigor, death (freeze) number, two branching and decline of saplings. Based on the analysis of variance, except for the vigor type 2 (with a modest decline and the damage between 10 to 25%), all 12 species demonstrated significant differences as far as the other characters were concerned. In total, the mean of viability percent, collar diameter and height were 88.88%, 13.56% and 5.44%, respectively. Type 1 vigor ( i.e. being healthy with the damage criteria below 10%) had the highest mean with 20.6% and represented the most significant difference as opposed to the other vigor types. Furthermore, amongst all 12 species, it was Pinus eldarica, Cupressus arizonica, Pinus nigra var. pallasina and Pinus brutia which had the greatest viability. By and large, the ecological condition of Kalaleh region (northern slope) proved to be more appropriate than that of Heresar region (southern slope) as far as all the characters studied here; the superiority which can be associated with its higher moisture level and less sunshine leading to a better superior balance. Such factors proved advantageous to the planted species and played a positive role in their success.

Species belonged to Muraenidae are members of the Anguiliformes order, comprise a group of fish fauna in the Persian Gulf and Oman Sea, which have ornamental, commercial and nourishing value. Such species undergone a study and the revising specimens for a whole year(from 2008 to 2009). The current research aims to revise the samples classification and systematic specimens of Muraenidae documented in museums, universities and research centers in Iran or collected from the fishing ports in Bushehr, Chabahar, Bandar Abbas, Bandar lengeh and the findings were compared to the most valid Ichthyology references on fish fauna in the Persian Gulf and Oman Sea; from the resulted total number of 27 eels, 13 samples belong to Muraenidae's family which comprises Gymnothorax sp, Gymnothorax kidako, Gymnothorax phasmatodes, Gymnothorax johnsoni , Rhinomuraena quaestia and Strophidon sathete were reported for the first time in the Persian Gulf and Oman Sea's waters.