Iranian Journal of Forest and Poplar Research
Year:2013 | Volume:21 | Issue:1 (51)|Papers Count:15

Changed environmental conditions, reactions of biotic factors and increase in invasive species due to anthropogenic or natural disturbances, will change composition and diversity of plant communities over time. Therefore, measurement of species diversity can be useful for disturbance and ecosystem management analysis .Oak stands of Dalab Park is located 25 km north west of Ilam was selected for invasive plant and species diversity studies and their effects on plant vegetation, due to their different disturbance regimes, including "grazing", "fire" and "control". Information of vegetation, soil and other environmental variables were collected from 77 sample plots, using random sampling method at various disturbance classes. Surface area of sample plots was determined, based on minimal area, using Helical Technique and Area-Species Curve. The size of sampling plots was 16×16 m. for tree and shrub species and 1×1 m. for herbaceous species. Whittaker´s nested plot method was used in order to record the herbaceous species. Two-Way Indicator Species Analysis, Indicator Species Analysis, Canonical Correspondence Analysis and Numerical Index method were applied to classify ecological groups, determine indicator species in each class, identify relationship between environmental factors and the studied plant groups and assess species diversity, respectively. Results showed that t disturbance affected composition and diversity of such forests. Grazing, fire, soil and topographical factors were identified as the most influential factors on plant composition. Fire led to an increase in vegetation into annuals and ruderal species of plant vegetation, including Coronilla scorpoides, Torilis leptophylla, Boissiera squarrosa, Taeniatherum crinitum, Onopordon carduchorum, Cirsium spectabile and Carduus pycnocephalus. Grazing increased mostly frequency of non-palatable and resistant species to grazing and soil compaction, including Bromus tectorum, Picnomon acarna, Stellaria media, Rochelia disperma, Holesteum umbellatum, Euphorbia macroclada, Turgenia latifolia, Rhagadiolus angulosus, and Valerianella vesicaria. Highest richness and diversity of the species was recorded in moderate grazing disturbance and control classes, whereas the lowest richness and diversity was recorded in intense and light grazing which is consistent with the theory of intermediate disturbance.

The trial was conducted by planting 10 different open crown poplar clones near Gheshlagh riverside at Sanandaj city of Kurdistan province of Iran from 2001 for seven years, in order to study their adaptability and wood yield. Poplar plantation started from 2002 based on randomized complete blocks design with three replications by a 4x4 m. spacing (25 saplings per plot). Poplar characteristics, including total height and diameter at breast height (dbh) were measured annually after planting. Results showed that effects of first and second years after planting on sapling's cumulative growth of dbh, height and volume were not significant. The average of dbh, total height and volume at end of 2007 were 18.69 cm., 11.51 m. and 109.88 m3 ha-1, respectively. There were significant differences between the clones in respect to their growth performance, during the trial period. Three of the clones, including P. euramericana 561.41, P. deltoids 63.2 and P. deltoids 63.1 had the best adaptation and performance among the studied ones at Sanandaj ecological conditions. The average dbh, total height and volume increment of the outstanding clones were 22.05, 21.44 and 20.6 cm; 12.68, 12.67 and 12.75 m. and 26.5, 24.7 and 23.66 m3 ha-1 y-1, respectively. Their quality was perfect as well with low damage caused by dry stress, good to excellent freshness, low contamination to pests (without stress condition) and straight and smooth stems or having one or two branches.

The study was carried out to investigate relationships between physiographical factors and some tree's characteristics and forest structure at Kurdistan province of Iran. For this reason, effects of slope (five levels), aspect (four levels) and elevation (four levels) on tree's characteristics (dbh, total height and crown area) and forest structure (diameter distribution curve, density and basal area) were investigated. The trees were sampled, using 77 plots (1000m2 area) under systematic randomized sampling method, based on completely randomized design. Results showed that the physiographical factors affected the tree's characteristics significantly. The greatest tree's diameter, total height and crown cover were found on low slopes, eastern and northern aspects and high altitudes. The interaction analysis showed that slope had important role on most of the tree's performance. The diameter distribution patterns at all physiographical conditions were uneven-shaped normal and Kortiusis and low tree density at low diameter classes, indicated poor regeneration at past. The diameter distribution curves at intermediate slopes and altitude and northern slopes showed an adequate condition, in which density indices (number and basal area per hectare) were also at best conditions. In contrast, sites with southern aspects and low slopes had poor density indices, for this reason they need high attention and preference in forest management projects. It could be concluded that difference in species composition and human intervention are main sources of tree's characteristics and forest structure variation at physiographical units.

This study reconstructs 850 years of vegetation dynamics, climate change, and human impact in Kelardasht (Mazandaran province, N Iran), based on a palynological study of Tepe Kelar mire (1080 m asl; N 36o 31′ 17′′; E 51o 11′ 57′′). The pollen record of Tepe Kelar shows substantial changes in vegetation as a function of human impact and climate. In the last millennium beech (Fagus), hornbeam (Carpinus), and oak (Quercus) have been the most abundant tree species in the forests surrounding the Kelardasht plain; however, due to increased human interference, oak has severely declined over the past 1-2 centuries. Maple (Acer), ash (Fraxinus), and elm (Ulmus) may have been accompanying tree species on the slopes facing Kelardasht. Our study indicates that alder (Alnus) and wingnut (Pterocarya) once were abundant on the plain, but that human-induced hydrological change, particularly drainage of wetlands, has decimated alder and eliminated wingnut. The dramatic decline of wingnut at around 700-800 BP has also been found in other palynological studies from the central Hyrcanian forests and from Colchis in western Georgia. Being synchronous with the so-called Mediaeval Climatic Anomaly, a regional climate change could also have been responsible for this phenomenon. The occurrence of several pollen types indicative of human presence, such as Juglans regia and Avena triticum, may point to human habitation in the area at least since 850 years ago. Substantially higher values of Sambucus ebulus, Polygonum aviculare, and Plantago lanceolata indicate intensified anthropogenic vegetation change and land use over the past 300-400 years.

The aim of this research was to determine the optimal rotation period in poplar, in which the net present value will be maximized regarding to the stumpage price, rate of interest and annual growth. Data such as annual growth, stumpage price and discount rate were used in order to determine the optimal rotation period. First of all a growth model of poplar tree was predicted. Results indicated that a quadratic model with significant level of 0.05 is the best model, based on annual growth and volume per hectare. Although, the results indicated that a cubic function is the best model for determination a relationship between age and stock with significant level of 0.05. Then, the stumpage price was predicted based on autoregressive model. Finally, the optimal rotation period for different plantation density was determined, based on price and growth models as well as different rate of interest. Results indicated that the optimal rotation age will be variable and between 8 to 25 years, due to different rate of interest and plantation density.

Maple (A. velutinum) is a native species in Iran, used mostly in monoculture or mixed forest plantations. Silvicultural operations in such stands, particularly thinning might strengthen their wood production and improve their quantitative and qualitative characteristics. For this reason, two maple stands were selected which were planted during 1991 by Mazandaran Wood and Paper Company at Sari area of Caspian Forests. One of the stands (Berenjestanak District) was thinned and the other one (Chaibagh District) was unthinned (control). The systematic and random sampling method with circular plots (100m2) was implemented and 39 and 33 plots were allocated in the thinned and control stands, respectively. The measured characteristics of the species consisted of stem diameter, total height, density, stem quality, crown diameter and form factor. Results showed that there were significant differences between the two stands in respect to the measured characteristics (r<0.01). The average stem diameter, total height and basal area in the thinned and control stands were 19.98 cm., 13.84 cm, 18.32 m., 17.46 m., 30.74 m2 and 15.7 m2, respectively. Overall, on time thinning operations at appropriate intensive levels are suggested for forest experts in order to reduce high plantation costs and increase wood production quality and productivity.

Forests degradation and their convert to pasture, agriculture and urban or rural land use, occurs annually at high extent, in which make high damages to natural resources. In the current research, the logistic regression model was applied to identify effective factors of forest degradation and zoning possible forest degradation at Vaz and Lavij basins. Landsat Satellite images were used to identify land use variation within 1998 to 2006. Results showed that forest area was reduced from 81.97% in 1998 to 77.43% in 2006. Distance from village, river and road and also slope gradient were considered as independent variables, whereas land use change (forest degradation) was considered as dependent variable in the model. The logistic regression model was applied at two cases: classified and standardized variables. The obtained coefficient from the applied model at classified case indicated that forest degradation is more likely to happen at 0-100 m. distance from village, whereas the obtained coefficient from the applied model at the standardized case, indicated that there was negative relationship between the independent and dependent variables. Overall, zoning map of possible forest degradation at the studied area was developed at five levels: severe, high, moderate, low and very low, based on the calculated coefficients. According to the results achieved from modeling at classified case, 11.06 % of the studied area has potential for sever forest degradation.

Mapping of natural forests in mountainous areas is difficult and expensive. For this propose, satellite remote sensing data is an appropriate solution. In this study, satellite remote sensing ETM+ data was used to develop map of forest canopy cover density, applying FCD model at Shafarud basin of Guilan province of Iran. Forest canopy cover density map was developed, using different density classes, including: 5-25, 25-50, 50-75, 75-100 and control (without forest cover). In the method of forest canopy cover mapping, using FCD model, four indices, including plant vegetation, soil, shadow and temperature were applied on Landsat ETM+ image data, considering an appropriate threshold. Then advanced shadow index and shadow index were uniscaled and calculated. Plant density index and plant canopy cover density map were developed and achieved by percentage, based on FCD model. The accuracy of forest density classification map was estimated, using a map based on 100% Orto-photo-mosaic of aerial figures, drawing a 10 x 10 mm. network and appropriate enlargement of the photos. The developed figure was classified, using method of maximum probability. The overall accuracy and Kappa index were 71 % and 0.61, respectively. The results showed that the developed map, using FCD model and Landsat ETM+ dta, was close to natural land data and facts. Considering the erroe's matris at seven processes of FCD calculation, showed that the model was insufficient for moderate located, thinned and semi-dense canopy covers, whereas it was sufficient and well detected by the model at high located, very thinned canopy covers (<5%) or stands without canopy cover.

Populus euphratica is a native tree species of Iran and ecologically has a wide distribution. Its tolerance to high level of air temperature and soil salinity is one of its important characteristics. For this reason, it has a high potential for afforestation in dry lands and deserts. The aim of the study was to evaluate the growth, morphological and physiological characteristics of different provenances of this species, in order to introduce the best ones for plantation on arid and saline lands. Among the provenances which have been tested during 2011 at Garmsar Desert Station, based on a randomized complete blocks design with three replications, 16 provenances were selected for the trial. Leaf sampling from the selected provenances was made in order to measure proline, sugar, chlorophyll, carotenoides and total proteins. Growth parameters, including stem collar diameter, total height, special leaf area and dry leaf weight were also measured. Analysis of variance of the physiological characteristics showed that there were significant differences between the provenances in respect to their chlorophyll, carotenoides, sugar, proline and total protein. According to the Duncan classification, most of the provenances ranked in one group for their average proline content. The provenances of Golestan, Khojir, Kerman, Zabol, Kashan and Dezful achieved the widest stem diameter (1.15-1.95 cm.), total height (1.15-1.51 m.) and statistically ranked in one group. Soil salinity had negative effect on height growth. The outstanding provenances were introduced for plantation in sites, ecologically similar to Garmsar condition.

In recent years, spring late coldness has caused a lot of damage to mountain ash seedlings in the mountainous nurseries. This research aimed to reduce mountain ash seedlings damage due to spring late coldness. The research was carried out during 2007 and 2008, in Darzikola nursery (Farim Wood Co.), located 17 kilometers far from southeast of Pol-e-Sefid city of Mazandaran province of I.R. Iran. Seeds were treated by two levels of seedling cover (nylon sheet and control), and four levels of seed sowing dates (Fourth week of February (1), first week of March (2), fourth week of March (3) and second week of April (4)) under split plots design with three replications. The trial was repeated for two years. Results showed that effects of sowing date on seed germination rate were significant (p<0.01), whereas effects of cover treatments and interactions between the two treatments were not significant on seed germination rate. Effects of cover treatments on seedling height were significant (p<0.05). Seedling sowing date treatments had different effects on seedlings height. For instance, seedling height increased gradually at first treatment, whereas reached its maximum height at third treatment and then decreased. Effects of seed cover, sowing date and their interactions on mortality rate of the seedlings due to spring late coldness were significant. The mortality rates of the seedlings at covered and control treatments were 80 and 20 percent, respectively. There were not significant differences in seedling loss at different levels of sowing date treatments when they were covered by nylon sheet, whereas at control treatment, the mortality rate decreased significantly when the sowing date reached the second week of April. Due to seedlings propagation productivity and mortality rate caused by coldness, it is suggested: first to sow the seeds at 15th March to 1st April, after application of one year cold stratification treatment and second to cover the plots containing the mountain ash seedlings by nylon sheets against probable coldness.

Jojoba (Simmondsia chinensis (Link) C. K. Schneid) is a very tolerant shrub to drought condition. Its seeds contain about 50% oil or liquid wax and have a high potential for cosmetic, pharmaceutical, food, etc. In order to study the success of vegetative propagation of jojoba for unique sapling production and comparing them with sexual propagation, some of the annual rooted cuttings and seedlings of the species were planted in 2006 at Jahrom Research Station at same age. Survival and growth characteristic, including total height, crown diameter, number of branches and seed quantity were measured and recorded for five years. The survival of cutting and seed origin shrubs after five years was 90 and 82 percent, respectively. The Duncan analysis showed that total height and crown diameter of cutting origin shrubs (male and female) was significantly greater than the seed origin ones (ρ<0.05). In addition, average number of main branches of female seed origin shrubs was significantly more than the cutting origin shrubs (male and female), but average seed mass of individual cutting origin shrubs was greater than the other ones (r<0.05). There were not significant differences between the two kinds of shrub in respect to their resistance to coldness. It is suggested to use rooted cuttings or explants to establish jojoba plantation at irrigated areas and for seed production, and seedlings for establishing plant cover at arid areas (soil conservation purpose).

Phytoremediation is an emerging, safety, cost-effective and potentially effective technology applicable for restoration of heavy metals contaminated environment. In order to study the remediation ability of woody plants used in Sanandaj urban forestry, we measured accumulation of Pb, Zn, Cd and Mn in five woody species, including Platanus orientalis, Ulmus carpinifolia, Fraxinus rotundifolia, Biota orientalis and Pinus nigra, planted in the center of Sanandaj, capital of Kurdistan province of I.R. Iran (as a pollutant area) and Kurdistan university court (as a control area) as well. Impact of the metals on some physiological traits of the species were also studied. For this reason, a completely randomized factorial experiment design with two factors, including 1- site at two levels (control and pollutant area) and 2- species at five levels (crock cypress, black pine, ash, elm and plane) with five replications, was used. Results showed that the accumulation of Pb, Zn and Cd in most species in the pollutant area was significantly higher than that of the control area (ρ<0.05). Maximum accumulation of Pb and Cd was observed in B. orientalis, Zn in F. rotundifolia and Mn in U. carpinifolia. The chlorophyll pigment in the leaves of all species in the pollutant area was lower than in the control area, while proline was higher. The highest amount of chlorophyll and proline was observed in P. orientalis and U. carpinifolia, respectively.

According to the results of the current research, a new approach in application of dendrochronology, using broadleaved tree rings, as main element of productivity, to evaluate forest ecosystem productivity, has been introduced. In this investigation, tree ring widths of sample cores which have been taken by borer from various species at different elevations, have been analyzed to evaluate their productivity and possible competitions between species. Ecological application of dendrochronology is main aspect of this study. Results provided in this research, are part of a wide range of dendrochronology study which have been taken during more than six years (started in 2006) to consider climate change impacts on Hyrcanian forest ecosystems. Target species in this study are beech tree (Fagus orientalis Lipsky), oak (Quercus castanaefolia C. A. Mey.), hornbeam (Carpinus betulus L.), alder (Alnus subcordata), and maple (Acer velutinum), which have been selected in Galugah forest district in Mazandaran province. After visiting the forest site and considering the adapting maps, sample cores were collected along a transect line (profile) at three elevation levels, namely 350, 800, and 1380 meters above sea level. Target trees were more or less at same ages. In the study region, during the last 54 years, precipitation trend shows a decrease by 372 mm and temperature trend shows an increase by 0.59oC. Variability in different species responses to inner (competition between species) and outer elements (environmental and climatic changes), at various elevations are highly dependent on species’ nature. Tree ring widths of Fagus orientalis Lipsky in low elevation during last 55 years has decreased, but tree ring widths of this species in medium elevation in the same period has increased. Tree ring widths of beech tree in high elevation have not changed significantly.

In order to collect, identify and evaluate the morphological and phonological characteristics of Willows (Salix sp.) accessions of Kurdistan province of I.R. Iran, the trial was conducted during seven years, started from 2001. After identifying and recording characteristics of elite mother trees of willows at their natural habitats, cuttings were collected and planted at Zale nursery at Sanandaj city during three years (2003-2005). Transplantation of 2.2 saplings (two year old root and shoot) to collection was made by nine saplings per plot by 3x3 m. spacing at early April for three years (2003-2005). The phenological, botanical and morphological characteristics were recorded at nursery and collection, regularly. Diameter and height growth was recorded annually at thr end of autumn. Results showed that willows grow at all ecological parts of Kurdistan province, such as urban margins, fields, valleys and particularly river banks. Overall, 65 accessions of willow species were collected from different habitats, which 58 are well established at the collection and seven were eliminated at different stages. The collected cuttings during March performed better than the ones collected during April and May. The 58 established accessions at collection belonged to five species as follows: Salix excelsa (38.6%), S. alba (36.8%), S. triandra (17.5%), S. aegyptica (5.3%) and S. babylonica (1.7%), of which the first three species consisted more than 90 percent of Salix species at Kurdistan province. The variance analysis result showed that there were significant differences between the even-aged accessions, different species, and different age groups at the collection in respect to diameter and height growth (r<0.01). Overall, diameter and height performance of Salix excelsa (14.08 cm and 7.9 m.), S. triandra (12.91 cm and 7.09 m.) were better than S. alba (12.5 cm and 6.43 m.).