Iranian Journal of Forest and Poplar Research
Year:2016 | Volume:24 | Issue:3|Papers Count:25

Landuse change is one of the most important influential factors on the protection of natural ecosystems, since it greatly contributes to, for example, stabilizing soil and avoiding its erosion. This study aimed to evaluate the effect of different landuses on soil carbon sequestration potential in Chahartagh-e Ardal area of Chaharmahal and Bakhtiari province. To this aim, six different landuse types including natural forest, disturbed forest, enclosure forest, garden, grassland and agriculture were selected, followed by randomly drawing ten samples in each landuse type. In addition, quantitative parameters of existing vegetation, and 60 soil samples were also taken from the 0-60 cm soil depth in each plot. Soil analysis was performed to determine the texture, bulk density and soil organic carbon. The results showed that enclosure forest has the highest rate of carbon sequestration in soil among the different land uses (47.466 Mg C ha-1) and the lowest rate related to disturbed forest (13.689 Mg C ha-1), which was attributed to its appropriate vegetation and ecosystem dynamics. Moreover, a significant difference (p< 0.01) was observed. The results suggest that forest ecosystems that have not been influenced by human interferences play an important role in long-term storage of soil carbon. In addition, any interference in natural ecosystem condition can be associated with negative impact on different levels on soil carbon storage.

Ecohydrological functions of canopy are significantly influenced by landuse change.This study was conducted across four current landuse types within the Gale-gol watershed (Khorramabad, Lorestan), including semi-natural forest, disturbed forest, forest farming, and orchards established on converted Brant`s oak (Quercus brantii Lindl.) stands. Field measurements of precipitation (P) and T were made over a period of 12 months starting from January 2013. Four rain collectors were placed in an open area adjacent to each of the landuse types to measure P. In addition, 12 trees were randomly chosen for each of the landuses and four throughfall collectors were installed under the canopy of each tree to measure T. Tree parameters were measured using 15 sample plots of 2500 m2 for each landuse type. I and S were estimated using P and T measured data. The results showed a rate of annual P=526.3 mm. Furthermore, ANOVA results revealed an outstanding difference between T and I across four investigated landuses including semi-natural forest (T=353.9, I=172.4 mm), disturbed forest (T=403.0, I=123.4 mm), forest farming (T=429.8, I=96.5 mm), and orchards (T=418.3, I=108.0 mm) at 5 percent significance level. The ecohydrological functions of canopy in semi-natural forest (with 60% canopy and a density of 212 tree/ha) were associated with the minimum negative effects when compared to forest farming (with 26% canopy and a density of 144 tree/ha) and disturbed forest (with 11% canopy and a density of 52 tree/ha). The components of Linear Regression models also proved that the I estimated by P (0.794<r2<0.856) is more accurate than DBH (0.654 <r2<0.837). The findings of this study are concluded to improve the existing understanding of ecohydrological canopy function. This function can be implemented as a part of forest resources management to regulate the relationship between canopy and water resources cycle.

Different physiographic conditions and soil properties have resulted in the establishment of different plant communities in central Zagros forests. This study aimed to differentiate these plant communities by means of detecting the species similarity and relations between understory plant vegetation, physiographic conditions and soil properties. Sampling was conducted using 21 modified multiscale Whittaker plots that were randomly distributed amongst the vegetation types. In each plot, species name and canopy cover as well as physiographic data were recorded for each individual tree, and soil specimens were sampled. The relationships between understory vegetation and environmental variables were investigated by means of two way indicator species analysis (TWINSPAN) classification method as well as two ordination approaches, including detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA). The results of ANOVA, ordination, and classification in segregation of vegetation types showed that the distribution of vegetation types, species and also ecological species groups in central Zagros is affected by altitude, slope, geographical aspects, and the amount of soil organic C and N. Moreover, the results of vegetation classification segregated local vegetation into three ecological groups, including 12 indicator species. These results were in line with the ordination results. This study showed a high resemblance between the results of vegetation classification and ordination in accordance to the extent of study area (landscape scale) and random selection of sampling units at the physiognomic types and the ecotones.

There are several available indices to assess the group associations between species and sites in order to identify diagnostic species. In this study, we introduced 11 indices of species-site groups and evaluated their quality by means of a TFVI model and four numerical criteria, including average positive fidelity, sharpness, uniqueness and crispness based on of 168 releve of Buxus hyrcana habitats. We used a modified TWINSPAN classification of 168 releve (Nine vegetation community/site groups) to determine the species fidelity value. The results showed that new classification obtained from assigning releve using TFVI model based on IndVal, UbinB and Ochiai indices returned the highest values of the fourfold criteria in evaluating classification quality.Moreover, they achieved higher qualities compared to other indices. Also results of cluster analysis and PCA diagram showed that 11 species-site groups’ association indices can be divided into four groups. The scatter plot of association indices along two first axes in PCA (eigenvalues 0.556 and 0.365, respectively) explained 92% of total variation, and species fidelity values based on IndVal and Ochiai indices were similar and noticeably different with other indices. Finally, the results of this study revealed that IndVal and Ochiai indices have the most priority in determining diagnostic species of vegetation communities compared to the other examined association indices.

It is of crucial importance to assess the performance of the photosystem II efficiency, as the most powerful system in light reactions of photosynthesis that is able to provide required electron of system by splitting water. Late frost occurred mostly in growing season and during night in early spring often results in weakness and even death of plants. Therefore, selecting tolerant varieties is one of the most efficient methods to deal with late frost. Due to high diversity and wide dispersal, poplars significantly contribute to the worldwide supply of cellulosic resources. In order to investigate the effect of night late frost on functional component of photosystem II and a number of related physiological traits, seedlings of three clones of black poplar (Populus nigra L.) were exposed to the minimum night temperature of 16, 4, 0 and –20oC for three nights. To assess the revival potential, seedlings were further maintained in optimum temperature for 14 days. Data were analyzed using a factorial model with two factors of clone and minimum night temperature for each step of the stress and revival. Results revealed that maximum and quantum yield efficiency of photosystem II in different clones has different reduction patterns according to the efficiency of water splitting complex and plastoquinon pool (PQ). Thus, Iranian clone was concluded to be more sensitive than other clones. This difference was discussed in association with total soluble sugar, proline and chlorophyll concentration and electrolyte leakage rate of cytoplasmic membrane. In addition, the recovery process of the clones in revival period was discussed.

This research was conducted to study the spatial distribution of Brant's oak (Quercus brantii Lindl.) mortality using geostatistical prediction and mapping approaches in Dashte-e Barm, Fars province. Field sampling was performed based on a 500m×500m systematic random grid and 1200 m2 rectangular forest plots. Different geostatistical methods were used for plotting anisotropic empirical semivariogram and surface creation. Results of cross validation showed that ordinary kriging with spherical model achieved superior results. The models were used for wall-to-wall prediction maps with four classes, including<10%, 10-25%, 25-60% and>60% mortality. The 25-60%, mortality class occupied the largest area (3827 ha), whereas the<10% class covered the smallest portion of the study area (260 ha). In addition, the probability of mortality was spatially mapped, in which the probability of>60% tree mortality across the entire study site was shown to be less than 25%. This research concluded that Geostatistical kriging methods could be applied to predict and map missing tree mortality values in forest stands. Our analysis suggests that these methods can be used to generate prediction and probability maps in zagros oak stands for overarching goals such as forest mortality, pest and disease managements.

The commercial bole of trees in the mixed-beech forests contributes the majority of biomass and of carbon pool, and is associated with the majority of monetary values in the Hyrcanian forests of Iran. This research aims to accurately predict commercial biomass compared to the allometric equations and field measurements in the third district of Glandroud forests in Noor. After harvesting of the trees, each part of the bole was weighed in the field and wood pieces were extracted from each part. The pieces were then oven-dried, on which the specific wood density was measured. Biomass was simulated by artificial neural network (ANN) including the FFBP network. Allometric equations (logarithmic multiple linear regressions and transformed power function models) with different parameters were examined to study the simulation uncertainty.Diameter at breast height, commercial height and specific wood density (WD) were inputs to the allometric functions and ANN simulation. Architectures of different topology of studied network including transfer functions of Log-sigmoid and Tansigmoid with variety of hidden layers and neuron members returned different error estimations of forest commercial biomass. Diameter was one of the most effective factors to predict biomass using ANN. Moreover, increasing height and WD in the ANN reduced the uncertainty of simulation outputs. Adding height and WD with the different combinations in the allometric models increased the accuracy of response variable prediction. The root mean squared errors (RMSE) showed that although there was slight differences in the estimation accuracies of ANN and allometric models, the optimal ANN outputs were of lower uncertainty to spatially predict the response variables.

Fire is an integral factor in many forest ecosystems and is strongly influenced by human activities. The first visible effect of forest fire is destroying the existing vegetation, which results in the forest stand being host to more resistant species. Different plant species, including trees, show different responses to natural disasters such as fire according to their characteristics. In this study the fire resistant tree species in the Noghlehbar Rostamabad forest of Roudbar in Guilan province was investigated, since the area has been heavily damaged by fire in 2010. The area contained Parrotia- Carpinetum forest community, accompanied by oak, beech, maple and elem. In this study was used a full calipering method to determine the amount of damages to the trunk and crown, and a random sampling was used to determine species regeneration.The statistical tests revealed a significant difference between species in terms of their fire resistance. In addition, Oak was shown to be of highest fire resistance, while the Iron tree was of lowest one. The Elem species was able to produce the highest rate of post-fire regeneration, and the highest growth rate was observed in the Oak tree seedlings.

After over five decades of establishing plantations in Chitgar Forest Park in Tehran, no study has yet been carried out on the soil seed bank in this region. This study aimed to investigate the composition of above-ground vegetation and soil seed bank. Therefore, 30 releves were established with 450m2 area each. For sampling soil seed bank within each releve, two samples were randomly collected by hammering a 400 cm2 into the soil to a depth of 5-10. Following this, the soil seed bank was estimated using the seedling emergence method. All in all there were 22 families and 62 species in above-ground vegetation and 29 species from 13 families were identified in the seed bank. All species in the soil seed bank were present in the above-ground vegetation. The results also showed that the above-ground vegetation included a higher species richness than the soil seed bank. High similarity of the soil seed bank and above-ground vegetation showed that the soil seed bank has the potential for reclamation of above-ground vegetation, but the lack of tree species in the soil seed bank hampers the practicability of the reforestation with an emphasis on seed germination of the soil seed bank.Furthermore, because of the structure and the type of the previous above-ground vegetation across the test site, the natural tendency of the area is towards the non-forest species.

The cappadocian maple (Acer cappadocicum Gled.) is one the important maple species and native to the northern forests of Iran. The aim of this study was to investigate some habitat characteristics and quality of A. cappadocicum in the forests of south Sari in Mazandaran province. To this aim, parts of forests with high a presence of this species were selected and 93 sample plots of 0.1 ha each were established with selective sampling method in different physiographic conditions (elevation, slope gradient and aspect). Geographical conditions of each plot as well as the quantitative and qualitative traits of maple trees were recorded. To survey soil properties, 20 soil samples were also randomly collected. The results showed that the number of maple trees varied between 1 to 29 in each sample plot. Moreover, the Physiographic factors significantly affected the distribution of maple trees, and the highest abundance was observed between 21% to 40% slopes, Eastern aspect and altitudes ranging between 1501 to 1700 meters above sea level. On the contrary, the lowest number of erect maple trees was observed on 1 to 20% slope, East aspect and between 1701 to 1900 meters altitude, whereas vertical maple trees were mostly observed in 81 to 150% slopes, western aspect as well as 1901 to 2100 m above sea level. The maple trees were mostly abundant in loamy soils, but the thickest and highest individuals occurred on clay soils.

In this study, phytoremediation potential of Populus euramericana clone 561.41 to Pbcontaminated soils (0, 500, 1000, 1500, 2000 mg Pbkg-1 soil) was investigated in greenhouse condition in a completely randomized design. The results showed that the survival was decreased about 19.9%, 35.8%, 55.6% and 60.3% in the soil polluted with 500, 1000, 1500, 2000 mg Pbkg-1, respectively. However, increasing Pb did not lead to any notable changes in the length of root and stem. In addition, leaf area and biomass of root, stem, leaf and total (till 500 mg Pbkg-1 soil) did not decrease, as well. The Pb concentration, content of plant organs, the greatest, and the lowest values allocated to root and leaf increased along with increasing Pb concentration of soil. The greatest values of translocation factor and tolerance indices of root, shoot and total plant were observed in 500 mg Pb kg-1. The results generally demonstrated the good tolerance of the seedlings of P. euramericana clone 561.41 to Pb heavy metal in 500 mg kg-1 concentration. At higher concentrations of Pb, the results presented an acceptable tolerance, though the tolerance index of seedlings was reduced. Due to significant accumulation of Pb in the root (phytostabilization), this clone can therefore be introduced as an appropriate clone for phytoremediation of Pb-contaminated soils.

Basatin Estuary is located in the north of the Persian Gulf and in the east of Boushehr province, which is opening into the Nayband Bay and is connected to the Gavbandi River. This estuary is considered as one of mangroves forests in the northern shores of the Persian Gulf because of its spectacular ecological condition. On the other hand, Basatin estuary is setting for enrichment of several kinds of pollutions during the recent years. Therefore, this research aimed at 1) highlighting the role of the mangrove forest in mitigation and reducing concentration of pollutions, 2) estimating the concentration of metallic and metalloid elements, in particular oil bonded and terrestrial bonded in surface and in the sediment columns of Basatin Estuary, and 3) identifying key horizons in the column sediments and their compatibility with the environment and man-made events. Therefore, a comprehensive sampling of the sedimentary faces and chemical analysis of wide range of elements (50 elements) were implemented. Totally 120 sediment samples were recorded and were analyzed using ICP-OES devices. In addition, statistical analysis was carried out to reveal relationships between similarity or dissimilarity elements. The results approved the research hypothesis, and e.g. showed that changing in the estuary mouth in 1991 has resulted in limitation of hydraulic circulation of tidal currents and caused a severe increase in sediment accumulation, followed by covering aerial roots by sediments and finally drying of mangrove trees.This process has a direct role in the enrichment of heavy metals in the environment.Furthermore, the uppermost layer of sediment column (0-25 cm) has experienced moderate to high degrees of pollution by petrochemical industries. This layer was significantly enriched by Zr, V, Ti, S, P, Ni, Mn, Li, Cr, Co, Ce, Cd, Bi, Ba, as elements. Finally, time correlation of key horizons and environmental events showed that the average rate of sedimentation in the estuary Basatin fluctuated between 1.8 and 2 cm per year.

In traditional poplar farming, predicting growth rates in different stands is required to evaluate poplar wood production. Six white poplar (Populus alba L.) stands in river bank of Zayandehrood River in Isfahan province were selected for the present study. Attributes including tree diameter, height, diameter and volume growth rates were measured and calculated. The raw data were subjected to analysis of variance (ANOVA), and the means were separated by Duncan methods. The ANOVA results showed that the effect of P. alba stands on height, diameter, mean growth and the basal area were highly significant (P<0.01). In addition, significant effect was observed for the yield per ha timber volume (P<0.05). The 4th stand showed the greatest diameter, height and basal area, whereas the 6th stand revealed the highest timber volume per ha. Results also showed that the annual growth rates in difference stands ranged from 16.53 to 47.25 m3 per ha, which was affected by both stands and plant densities. This maximum timber production was reached at the maximum plant density. The study concluded that an adequate plant density and proper stand management are crucially effective on quality and quantity of poplar timber production.

Knowledge on silvicultural characteristics of forest stands is prior to any forest management practice. The objectives of this study were to determine the forest types and to explore some quantitative and qualitative characteristics of Arasbaran forest protected area along an altitudinal gradient. Therefore, circular plots of 400 m2 at 50- meter elevation intervals were established along five altitudinal transects, 100 meters apart, from the lowest (1100 m a.s.l) to the highest (1725 m a.s.l) forest limit. In each plot, the physiographic conditions including slope gradient, altitude and geographic coordinates were determined. Woody species were identified and the diameter at breast height (dbh) of all trees above 7.5 cm dbh, as well as origin, health status, number of stems and tree leaning were measured. In addition, the regeneration frequency of each individual tree taller than 1.30 m in three diameter classes (0-2.5, 2.5-5 and 5-7.5 cm dbh) and shorter than 1.3 m in three height classes (0-10, 10-50 and 50-130 cm) were examined within 100 m2 regeneration plots. Four forest types including Carpinus betulus - Quercus petraea (1100-1400 m a.s.l), C. betulus - Q. petraea - Acer campestre- Fraxinus excelsior (1400-1500 m a.s.l), C. betulus - Q. petraea - A. campestre (1500-1650 m a.s.l) and C. betulus - Q. macranthera (1650-1725 m a.s.l) were distinguished along the altitudinal gradient. The highest number of stems per ha (mature and regeneration stands) and average basal area were observed in C. betulus - Q. macranthera type, whereas the highest average dbh was recorded in C. betulus - Q. petraea forest type. Finally, seed regeneration was most common in C. betulus - Q. petraea - A. campestre forest type.

This research investigated the effect of canopy gaps created by single-tree selection method on humus layer depth within a managed oriental beech (Fagus orientalis Lipsky) stand in Hyrcanian region. To accomplish this, 16 gaps were selected in 4 classes (small, medium, large and very large) with 4 replications for each sample in a beech stand in Alandan district, Sari (Mazandaran province). Humus layer depth was measured in center and cardinal points of the gaps. In addition, humus was sampled based on composite samples for chemical experiments. The results showed a significant difference of humus thickness among gaps. The correlation coefficients indicated that the total N, P, K, organic carbon and C/N ratio were decreased with increasing humus depth. Humus layer depth in gap center was lower than that in the edge of gap, and the highest humus thickness was observed in the northern geographical aspect. In general, the result of study revealed that canopy gaps created by single-tree selection method affect the humus layer depth after 8 years, which in turn indicates the important role of gaps within forest ecosystems.

In this research, Eldarican pine (Pinus eldarica Medw.) pure stands with two densities were sampled along with a mixed stand with river red gum (Eucalyptus camaldulensis Dehnh.) in a systematic randomized design. Quantitative traits of trees including diameter at breast height (dbh), height and crown diameters were measured, followed by calculating the basal area, volume, stability index, crown area and annual increment of quantitative variables. In addition, qualitative traits including forking, twisting and trunk decay were also recorded for each tree. Analysis of variance (ANOVA) and Duncan tests were applied to analyze data and compare groups. Results indicated a significant difference between stands for all traits except for height and mean height increment.Furthermore, the mixed stand was superior in dbh and its mean annual increment, basal area and its increment, volume and its increment, stability and crown area. Branchless trunk of trees was significantly longer in pure dense stand compared to the others. Most forking and twisting was seen in mixed stand, yet the highest decay was observed for the pure dense stand. Finally, the study concluded that a mixed scenario should be preferred for Eldarican pine due to its better usage of the site capacity, in particular by owing to the fact that mixed stands are considered to be of more sustainability from an environmental and landscape management perspective.