Defects in Properties of wood are used as common indicators for grading logs. In this study, the logs of various woody species from ten different forestry projects have been evaluated based on their measured defects.The results of this study showed that the average diameter of acceptable knot for the first 3 meters of the trunks was 2.8 cm for maple (the least value) and 7 cm for hornbeam (the highest value), respectively. Moreover, the knotless portion of the first 10-meter-Iong trunks was 12.2, 32.4 and 20 percent for hornbeam, elm and beech, respectively. As for pith decay of trunk, the least and the highest values were 56 and 84 percent which were associated with maple and elm, respectively. As for trunks with bent defect, oak and basswood showed the lowest value (7 percent), while hornbeam showed the highest value (18 percent). This value for beech was about 10 percent. Bole taper (decrease of bole diameter of less than 2 cm per meter of length) was 65 percent in maple (the lowest value), and 96 percent in oak (the highest value). This value for beech was 75 percent. The lowest and highest values for defect of interlocked fibers were observed in boles of alder (68 percent) and oak (91 percent), respectively. The percentage of boles with interlocked fibers for beech was 89 percent. As for trunk with irregular annual ring, it was shown that hornbeam had the lowest value (82 percent). However, 94 percent of the other woody species didn't show such a defect. Finally, the lowest and highest percentage values for trunks with abnormal annual rings were 16.1 and 24.3 for oak and elm species, respectively.

Arasbaran forest (Gharadagh) that located in the north of Ahar City (eastern Azarbaijan province) are very important because of ecological condition and specific fauna and flora these non commercial forests including species such as Oak, Hornbeam, Walnut, cherry, elm and maple trees.The understory species are Cornus mas, Viburnum lantana, V.oppul us, Prunus.sp and in destructive area Paliurus spina-christi, Rosa.sp, crataegus.sp and Rubus.sp replace by main species.This study was achieved in order to finding natural regeneration structure in Sotanchi experimental forest (that is one subregion of Kalibarchi watershed).In order to fulfill this research, 36 primarily circle plots (0.1 ha) was measured after calculation of standard deviation, 139 main plots were indicated in a systematic random method.Also inside of every main plot, a qubic microplot (0.0004ha) was measured (nested plot).All species with diameter at breast height (d.b.h) from zero to 7.5 cm was measured in the main plots and also site factors, landscape and deforestation effects recorded.In every microplot, trees origin (high or coppice system) with d.b.h under 7.5cm was indicated. also the number of sprouts was counting and their average height calculated.This study indicated that regeneration structure in Arasbaran forest is in high and coppice system but coppice system is further.The main forest types that detected in this region are: Quersetum, Quercucarpinetum and carpinetum. The most regeneration was occurred in the north and northwest slopes under closed and semi-closed canopy because of appropriate humidity, temperature and light condition.Among all regeneration, the rate of Horn beam was 31.7%, Oak 29.3%, maple 8.2%, cherry 1.4% and other species (Cornus mas, viburnum lantana, juniperus.spp) were29.4%. The rate of seed regeneration was 28.7%. The average number of sprout on every stump was six and their average height was 3.7m.Oak and Hornbeam had the most regeneration power among existing species. The average height of sprouts in Maple, Hornbeam, Oak and Ash trees was very much but in Cherry trees was under 1m.

The durability of following five wood species: Zelkova carpinifolia, Ulmus glabra, Pterocarya fraxinifolia, Carpinus betulus and Acer laetum were studied. Wood blocks exposed to Trametes versicolor(a white rot fungus) under laboratory conditions according to DIN52176 standard. After 16 weeks incubation the heart wood of Z. carpinifolia showed 2.19% reduction in weight loss, while U glabra with 41.69%, C. betulus with 45.64%, A. laetum with 53.03% and P. Fraxinifolia with 43.08% weight losses were very decayed. For finding relationship between amount of wood decay and wood extractives a regression was carried out. The percentages of extractive materials by using T20403 standard were 13.84% in Z. carpinifolia, 4.51% in U. glabra, 2.74% in C. betulus, 3.88% in A. laetum, and 4.11% in P. fraxinifolia. Finally there was a negative correlation between rate of decay and amount of wood there was expect P. fraxinifolia. for all wood species extractives.

Ulmus glabra is one of the most important species of the industrial forests of northern forests of Iran. It is distributed from Gorgan (at the northeast) to Arasbaran (at the northwest). Due to development of Dutch elm disease in their habitats, countless numbers of this species have died and its presence in the forest ecosystems is in danger of being eliminated. There have been so many studies and efforts to save this valuable species all over the world. One of the efforts has been focusing on the evaluating both sound and diseased individuals in order to study natural balance ecosystem on sound physiological trees. nowadays one of the methods that are used to assess the ecosystem is to study the soil microorganism enzyme. Based on decreasing living conditions from top to bottom of the soil and also increasing living limits biological potential (constraints) towards the deep soil, the frequency of micro and macro organisms will decrease. Therefore the soil enzyme activities that are themselves related to these activities have a descending gradient from top to lower levels of soil. If the natural process for any reason will be abrupt may lead to an unbalanced ecosystem, which at the end will result to migrate to the living organisms to the lower levels. This will cause the change of the gradient shape and will follow a fluctuation. In this research, following the theorem and emphasis on phosphomonoesterase enzyme study, the soil of four forest habitats were studied which were located at Gorgan, Noshahr, Asalem and Arasbaran. Sampling was done on during Spring of 2004. The soil samples were analyzed and phosphomonoesterase activities were measured. The goal was to study the effects of natural balance on both sound and diseased elm individuals in normal and abnonnal ecosystems. The results were analyzed by GLM (General Linear Model) method and were compared by Tukey test. The results show that all of the sound elms are on the balance ecosystems (except one) and the diseased ones are on balanced. In addition the comparison of enzyme activity in each horizon in both groups shows that decrease of organisms activities in unbalanced elm ecosystem is quiet significant. In fact it can be stated that to save this valuable species it is not enough to only follow and find the resistant phenotypes and genotypes elms to Dutch elm disease. In other words, the interactions of different biological factors and balanced ecosystems have the main effects on saving sound elms, which may result to control the disease. This means that we have to induct a sound and powerful management for these forests.

The current research on wych elm was performed in Kheyroudkenar Forest, Noshahr. To detect the spatial pattern, Mean Square method was employed. Initially the locations of Wych elm individuals were recorded through GPS equipment, then transferred into Computer. For the design of grids with different sizes as well as Marking points on them. Arcview, Arcinfo and Idrisi software's were applied. The results indicated that Wych elm exhibits a pattern intermediate between random and clumped. This is the existing pattern of Ulmus glabra, because probably its real pattern has been changed due to Dutch elm disease as well as due to illegal cuttings.

The current research was carried out in Patom, Nam Khaneh, Gorazbon and Chelir Districts in Experimental and Educational Forest of Kheyroud. Thanks to extent of study area and dispersion of Wych elm on this area, the plot less sampling method was applied. After field inspection and identifying the remaining individuals of Wych elm trees (Ulmus glabra), ³d.b.h 10cm, Physiographic Factors (altitude a.s.l, aspect, slope were recorded. The results that Wych elm trees were distributed from 330 m to 1315 m above sea level. On north-facing and east-facing slopes, the numbers of elm trees were the most and least, respectively. In relation to slope or steepness, this tree dispersed on plain or flat terrain to steep slopes but the number of tree in gentle slope was more than higher slope.

In order to investigtion of woody plants biodiversity in different soils in two managed plant associations in Namkhaneh district of Kheyrudkenar Educational and Research Forest Sixty sample plots with 1000m2 Surface and 200´200m network were selected systematic elective in 125 hectres of each plant association and 250 hectares totally. In each sample 5 micro plots with 45m2 surface was elected. The results showed that the number of seedling in hectare in fagetum association is more than in carpino-fagetum association totally. With due attention to different beech seedling cycle in two association, the number of seedling in them are different. The number of Fagus orientalis and Caripnus betulus seedling in carpino-fagetum association is more than fagetum association, but the number of Acer velutium seedling is more in fagetum association is more than carpino-fagetum association. The number of Ulmus glabra, Tilia begonifolia, Acer cappadosicum, Quercus castaneifolia in fagetum association and carpino-fagetum association showed statistical significant difference. The natural structure of mass and reproduction style have been preserved during two period of exploitation by selective culting method.

Pathogencity of Ophiostoma ulmi and Ophiostoma novo-ulmi isolates against Ulmus parvifolia Jacq., was studied in greenhouse condition of the college of Crop Sciences, Pardis area of Gorgan University. Pathogen city rate of Ophiostoma ulmi and O. novo-ulmi isolates, isolated previously from north forest areas was evaluated on various ages of Chinese elm seedlings U parvifolia. Treatments were six months young elm seedlings, one year old and two years old elm seedlings. Wilt percentage of elm seedlings ten weeks after inoculation showed, that Chinese young elm tree is susceptible to aggressive isolates of O. novo-ulmi than O. ulmi. The highest percentage of wilting was observed on six months old seedlings and the lowest level of wilting observed significantly on two years old seedlings. The results indicated that oul isolate of O. ulmi and onu3 isolate of O. novo-ulmi showed significantly the lowest and highest percentage of wilting, respectively. Using of this elm, as resistant species against Dutch elm disease in country, to replace high susceptible species such as; Ulmus glabra and U carpinifolia and U carpinifolia var. umbraculifera by Ulmus parvifolia, and using in elm breeding programs for obtaining hybrid elms with favorite resistances is discussed.