مجله جنگل ایران
سال چهارم شماره 2 (تابستان 1391)

Eucalyptus (E.camaldulensis Dehnh) is one of the major plant species in Iran covering vast areas of plantations. This is a fast-growing species with high tolerance to harsh environmental conditions. Nevertheless the water deficiency in soil can be effective on the quality and quantity of plant growth. To study the effect of soil drought stress on water relationship in Eucalyptus (E.camaldulensis Dehnh), an experiment was carried out using weight and drainage Lysimeters in natural condition. The trials were implemented in Shahid Sadoghi control desert research station in Yazd for three years. The experiment was done with three treatments, 100% (control), 70% (medium stress) and 40% (high stress) field capacity (FC) in three replicates as complete randomize design. The results showed that the plant physiological behaviors including water potential, relative water content (RWC) and soluble sugar in leaves were affected by water availability for plant. Increasing the amount of soil moisture was not significantly effective on soluble sugar levels in roots and leaves proline levels (P-value> 0.05). By increasing the amount of soil moisture, the relative water content (P-value <0.001) increased. Increasing the amount of soil moisture reduced the water potential (P-value <0.001) and the amount of soluble sugars in leaves (P-value <0.001). These results showed that the osmotic adjustment through increases of soluble sugars in leaves, decreased the leaf water potential and increased drought resistance in this plant, although this ability is low. With these conditions, this plant could not be considered as drought-resistant plant.

Plantation and forest rehabilitation projects in the Zagros forests have been unsuccessful due to insufficient water supplies and problems in water availability. So, it is crucial to look for alternative methods not only to decrease water consumption but also increase soil moisture and seedling maintenance over a growing season. A new technique is using super-absorbent. We have used factorial experiment based on completely randomized design to examine the effect of applied super-absorbent on the growth of pistachio seedling. The treatments applied were: 1-super-absorbent in 3 levels (0, 50 and 100 gr), 2-irrigiation in 2 levels (5 and 10 lit) and 3-period in 3 levels (10, 20 and 30 days). Overall 18 treatments with 3 replications in each and 3 individuals in each replicate were examined. Furthermore, 9 individuals were considered as control samples as well. Results show that using 50 gr super-absorbent halved irrigation amount (5 lit) in 10-day period intervals. Using 100 gr super-absorbent with 10 lit water increased period of irrigation from 10 to 20 days. Also applying super-absorbent increased the height growth and diameter at collar growth compared with controls. We concluded that super-absorbent can diminish water consumption and irrigation frequency by 50%. We recommend this method to be economically justified and suggest it for restoration ecology projects in arid and semi-arid regions such as Zagros forests of western Iran.

This study is aimed at investigating the degradation intensity stemmed from tourist’s activities using degradation model in Namak-Abrod Forest. In tourist’s aggregation center located on the first line of telecabin station on the mountain top, a region with an area about 10 ha was selected and studied as environmental unit, then 10-meter strip or band was established in four main and four sub-main aspects and 100% inventory was done. Within the band, ecological vulnerability was computed and classified based on physiographic, soil, hydrologic and vegetation maps, then eight degradation factors were calculated in the region based on topographic maps, field observations and expert’s opinions. Using degradation model, degradation coefficient was calculated and classified and the study area was divided into two parts namely rehabilitation needed and conservation needed.

The main goal of this study was to evaluate the quality and cost price of seedlings production in two public (Zaghe) and private (Kalantari) nurseries in Lorestan province during a one-year period (Nov.2007- Nov2008). Pistachio (Pistacia atlantica var mutica), being relatively difficult to reproduce (from seed), and Poplar (Populus nigra), being relatively easy to reproduce (with cuttings), were selected for this evaluation. In order to evaluate the quality of seedlings, standard seedling (having desirablequalitative characteristics) as a qualitative indicator of seedling production was defined for the both species. In the second step, percentage of standard seedlings has been evaluated using a random sampling of produced seedlings. Then, the number and type of seedlings and total spent costs were extracted from accounts books of the both nurseries in the same period. As the total variable and fixed costs of nurseries have been spent at nursery scale, the allocated costs for pistachio and poplar seedlings have been calculated using area ratio (for landrent) and number ratio (all other costs). Finally, the cost price for an individual standard seedling of Pistachioand Poplar were calculated in both nurseries. Results showed that qualitative indicator of Pistachio and Poplar (the percentage of standard seedlings) in the Kalantari private nursery were found to be 3.5 and 1.2 times greater than Zaghe public nursery ones, respectively. In addition, the cost prices of a Pistachio seedling (24058 Rials) and a poplar seedling (17365 Rials) in the Zaghe public nursery were calculated to be 9.3 and 22.6 times greater than the cost prices of pistachio (2207 Rials) and poplar (735 Rials) seedlings in the Kalantari private nursery, respectively. Factors and variables such as the management of land, instruments and machineries, production scale, percentage of standard seedlings, may explain, among others, the observed diffreneces of cost prices in these nurseries. Such researches may help to improve management as well as financial and qualitative efficiency, especially in public nurseries.

Due to several problems in natural regeneration of Juniperus oblonga, asexual reproduction has important implication in restoring the habitat of this species. The aim of this study was to investigate the effects of different treatments including hormones, bed composition and light on rooting of Juniperus oblonga cuttings. Cuttings were taken from young stands and treated with 2500, 5000 and 7500 ppm of IBA and then planted in two different beds (fine and harsh bed) under white and red light as split plots. Data was analyzed using SAS software package and tested by Duncan method. Results indicated that bed composition and light treatments were significant (p-value <0.01) and hormones treatments were very significant (p-value < 0.05) in rooting of J. oblonga cuttings. The average of rooting in combination of white light, fine bed composition and IBA treatments (0-5000 ppm) at 28% was remarkable and can be used in mass production of J. oblonga seedling in rehabilitation programs.

In order to investigate the effect of environmental factors including slope, aspect and elevation on quantitative and qualitative characteristics of Juniperus excelsa subsp. polycarpus, Juniper stands were selected in Hezar Masjed mountains in northern Khorasan Razavi province, north-east of Iran. Maps of slope, aspect, elevation and landform were used and combined together to prepare homogenous polygons of land units. The stratified sampling was performed and three sample plots, each 1000 m2, were laid out in the land units. One sample from surface soil was taken in each plot in order to study the physico-chemical properties. Soil data were analyzed with Principle Component Analysis (PCA). Some parameters including number of trees, diameter at breast height, total height, crown diameter, crown cover, tress health and vigority and proportion of trees damaged by pest were measured. The results showed that elevation has significant effect on number of trees per plot, basal area per plot, and slenderness ratio, and mean crown diameter, number of regeneration per plot and tree's health. Slope gradient showed significant effect on some parameters including mean diameter at breast height, basal area in per plot mean crown diameter, total height and tree's health. The geographic aspect showed significant relationship with some parameters such as mean diameter at breast height, total height, slenderness ratio, mean crown diameter, crown cover, tree's health and proportion of trees damaged by pest. Landform had significant effect on total height, slenderness ratio, mean crown diameter and tree's health. Principle Component Analysis (PCA) showed that Phosphorus, clay, silts and pH are the most important factors on distribution of Juniperus excelsa subsp. polycarpus trees and moisture saturation had the least effect on this species.

Populus euphratica Oliv. is a native species in arid and semi arid zone of Iran distributing naturally in vast areas. The geographical and climatic differences led to morphological and genetic differences in this widely distributed species. Morphological characteristics of seeds might play an important role in genetic variation of Populus euphratica Oliv. In this study tree seeds of seven habitats of Populus euphratica were compared. For this reason, sampling was taken from seeds originated from different provenances for eight years in the experimental field of Alborz research center in the same environmental conditions. Five morphological Seed traits such as seed length, seed width, number of seed in any capsule, 1000 seed weight and the ratios of seed length to seed width, as well as germination percentage were measured. Results showed that there is significant difference between the provenances. Among seed traits, length and width of seeds were the most important factors in intraspecific differentiation of Populus euphratica Oliv.

Both vertical and horizontal vegetation structure determine habitat components important for woodland birds. We studied the impact of vegetation structure on bird species richness and diversity in a system of patchily distributed woodlands/cultivated lands oases in semi-arid steppes of central Iran. Line transects (totally 13.85 km) were used to assess bird species richness and diversity in each of the studied woodland patches (n = 12). Vegetation composition and structure were quantified in systematically located quadrates along the transects. Species richness and species diversity of birds were proved to be related to vegetation structure and diversity of woody plant species using regression analyses. Results showed that bird species richness increases with diversity of both vegetation strata and woody plant species. The results have implications for conservation of birds and other vertebrate taxa in woodland oases. Conversion of traditional multicultural woodlands to a system of monoculture patches may have profound adverse effects on avifauna diversity of the desert oases.

Decline in natural forests area due to various factors has caused the importance of plantation which is carried out with the aim of developing forest surface and wood production. Therefore, assessing the nature of plantations can play an important role in creating forests with better quality and quantity in the future. Nutritional status of habitat is an important qualitative factor in forest stand. The primary sources of nutrient elements in soil and leaf are nutrient retranslocation of old leaves. Retranslocation, movement and transfer of nutrient elements from aging leaves to tissue reservoirs occur each year, which is a key process in most ecosystems. In this study, the amount of nutrient elements (Ca, K, P, N, Mg) in summer and autumn leaves and amount of retranslocation of these elements in three plantation species (Acer, Zelkova and Pinus) of Darabkla-Mazindaran were measured. Sampling was conducted in two stages, one in mid-summer during ascending period of nutritional dynamism of trees, and the second stage in mid-autumn simultaneously with the beginning time of leaf fall in the same trees previously sampled. Results showed that there is difference between nutrient elements in summer and autumn leaves in the studied species. The magnitude of nutrient retranslocation was obtained in order of: P>Ca>N>Mg>K. Among the studied species, the highest retranslocation of Ca and Mg were determined in Acer, N and K in Zelkova and P in Pinus. The results of this study showed that the studied species had different nutritional elements and also different amounts of element retranslocation. Since the studied species had been raised under similar conditions, therefore it could be concluded that these differences are due to genetic variation of species.