Hyrcanian Forests Of Iran Research Articles

A phylogenetic assessment of the meadow lizard Darevskia praticola(Eversmann, 1834) from Iran.

The meadow lizard Darevskia praticola (Eversmann, 1834) displays a wide distribution range from the Western Balkans and Caucasus to the Hyrcanian forest in Iran. Based on previous studies, four subspecies have been described (D. p. praticola, D. p. pontica, D. p. hyrcanica and D. p. loriensis), but molecular evidence suggests two main phylogenetic lineages, Balkan and Caucasus. In this study we incorporated geographic records and analysed new samples from Alborz Mountains (Gilan Province, Iran), exploring their phylogenetic affinities using two mitochondrial markers (Cyt b and ND4). For the first time, Iranian samples are included in a molecular phylogeny. Our results meet the previous suggestions regarding the presence of a nuclear mitochondrial DNA fragment (numt) in Cyt b, causing misleading phylogenetic inferences since it renders the species paraphyletic. In contrast, the ND4 genealogy groups the species into a monophyletic clade, as expected. Samples attributed to D. p. hyrcanica (Azerbaijan and Iran) and D. p. loriensis (Armenia) are settled in a single clade with minute genetic distance, suggesting synonymisation.

A multi-sensor approach for improving biodiversity estimation in the Hyrcanian mountain forest, Iran

ABSTRACTModelling tree biodiversity in mountainous forests using remote-sensing data is challenging because forest composition and structure change along elevation. Topographic variations also affect vegetation’s spectral and backscattering behaviour. We demonstrate the potential of multi-source integration to tackle this challenge in a mountainous part of the Hyrcanian forest in Iran. This forest is a remnant of a deciduous broadleaved forest with heterogeneous structure affected by natural and anthropogenic factors. The multi-source approach (i.e. Landsat Enhanced Thematic Mapper Plus (ETM +), Advanced Land Observing Satellite/ Phased Array type L-band Synthetic Aperture Radar (ALOS/PALSAR), and topographic variables) allows us to propose a biodiversity estimation model using partial least square regression (PLSR) calibrated and validated with limited field data. The effective number of species was calculated based on field measurements of the biodiversity in the study area. In order to model species diversity in more homogeneous extrinsic environmental conditions, we divided data into two groups with relatively uniform slope values. In each slope group, we modelled the correlation between observed biodiversity and satellite-derived data. For that, we followed three scenarios: (A) multispectral Landsat ETM + alone, (B) ALOS/PALSAR alone, and (C) inclusion of both sensors. In each scenario, elevation and slope data were also considered as predictors. We observed that in all scenarios, coefficient of determination (R2) in gentler slopes was higher than that in areas with steeper slopes (average difference in R2: ∆R2 = 0.21). The highest correlation was achieved by inclusion of synthetic aperture radar (SAR) and ETM + (R2 = 0.87). The results clearly confirm that the multi-source remote-sensing approach can provide a practical estimate of biodiversity across the Hyrcanian forest and potentially in other deciduous broadleaved forests in complex terrain.

Leaf cuticle and wax ultrastructure of genus Alnus Mill. in Hyrcanian forests of Iran

The genus Alnus had three taxa in the old floral resources of Iran. Recently, five new taxa were added to the flora based on morphological studies. Individual samples were collected from 25 sites throughout three provinces covering Hyrcanian forests of Iran and classified into the eight mentioned taxa and then prepared for micro-morphological studies. Four groups of taxa including A. subcordata var. subcordata, A. subcordata var. villosa, A. orientalis, and A. glutinosa subsp. antitaurica had a specific structure. Similar structure was also found between two new species of A. djavanshirii and A. dolichocarpa, which were distinguished from the other groups. Simple trichomes with variation in size and density were observed among the taxa. Alnus subcordata var. villosa and A. glutinosa subsp. antitaurica had the densest trichomes on dorsal and ventral leaf surfaces. The results of this study show the suitability of ultrastructure features as a micro-morphological marker for solving the taxonomical ambiguities of the genus Alnus in Hyrcanian forests.

Molecular Identification of Ectomycorrhizal Fungal Communities Associated with Oriental Beech Trees (Fagus orientalis Lipsky) in Hyrcanian Forest of Iran

Oriental beech tree (Fagus orientalis Lipsky) is one of the significant tree species from ecological, economical and commercial point of views in Hyrcanian forest of Iran. This valuable tree is mostly found in the Hyrcanian forest of Iran. Like other forest ecosystems, there are vital symbiotic relationships between tree species and several microorganisms, especially mycorrhizae. Ectomycorrhizal (ECM) fungi play an important role in the forest ecosystems. They uptake heavy metals and other toxic materials from the land. Hence, the identification of these organisms would provide knowledge on the forest management. Sampling was conducted in 1500–2100 m altitude. The fungi were collected on Oriental beech trees from Savad-Kooh forest (located in Mazandarn, Iran) and identified by molecular method. For molecular verification of the fungal species, roots were identified by rDNA-ITS analysis. The sequences of the ITS regions of the nuclear rDNA were obtained and compared with those present in the GenBank. Thirty fungal species were identified in beech communities. Cortinariaceae and Inocybacea families with 50 and 7% had the highest and lowest plenty, respectively. Moreover, twelve species of ectomycorrhizal fungi were identified as first reported for Iran and twelve species of ectomycorrhizal new host in the world. This valuable species grows in Hyrcanian forest of north Iran. Oriental beech lives in contact with other plants and microorganisms especially mycorrhiza. Collection and identification of ECM fungi were done in Hyrcanian forests which are habitation of Oriental beech forests. The members of Cortinariaceae and Inocybacea families were most predominate among other fungi. Nonetheless, twelve fungal species were found as new report in ITS region for Iranian fungal flora.

Mapping Lorey’s height over Hyrcanian forests of Iran using synergy of ICESat/GLAS and optical images

ABSTRACTLorey’s height, representative of mean height in uneven-aged forest stands, is a valuable parameter for forest ecosystem management. While in situ measures provide the most precise information, remote-sensing techniques may provide less expensive but denser and more operational alternative of Lorey’s height estimation over highly mountainous areas. This research aims first to evaluate the performances of two nonparametric data mining methods, random forest (RF) and artificial neural network (ANN), for estimation of Lorey’s height using ice, cloud and land elevation satellite/geoscience laser altimeter system (ICESat/GLAS) in Hyrcanian forests of Iran and then to provide Lorey’s height map using a synergy of ICESat/GLAS and optical images (TM and SPOT). RF and ANN GLAS height models were developed using waveform deterministic metrics, principal components (PCs) from principal component analysis (PCA) and terrain index (TI) extracted from a digital elevation model (DEM). The best result was obtained using an ANN combining first three PCs of PCA and waveform extent ʺWextʺ (RMSE = 3.4 m, RMSE% = 12.4). In order to map Lorey’s height, GLAS-estimated heights were regressed against indices derived from optical images and also topographic information. The best model (RF regression with RMSE = 5.5 m and = 0.59) was applied on the entire study area, and a wall-to-wall height map was generated. This map showed relatively good compatibility with in situ measurements collected in part of the study area.

Quantitative and Spatial Analysis of the Spatial Pattern of Wild Cherry (Prunus avium L.) in Hyrcanian Forests of Iran (Case Study: Forest Management Plan of Hajikola-Tirankoly)

Quantitative and Spatial Analysis of the Spatial Pattern of Wild Cherry (Prunus avium L.) in Hyrcanian Forests of Iran (Case Study: Forest Management Plan of Hajikola-Tirankoly)

Mixed-effects modeling for tree height prediction models of Oriental beech in the Hyrcanian forests

Height–diameter relationships are essential elements of forest assessment and modeling efforts. In this work, two linear and eighteen nonlinear height–diameter equations were evaluated to find a local model for Oriental beech (Fagus orientalis Lipsky) in the Hyrcanian Forest in Iran. The predictive performance of these models was first assessed by different evaluation criteria: adjusted R2 (R adj 2 ), root mean square error (RMSE), relative RMSE (%RMSE), bias, and relative bias (%bias) criteria. The best model was selected for use as the base mixed-effects model. Random parameters for test plots were estimated with different tree selection options. Results show that the Chapman–Richards model had better predictive ability in terms of adj R2 (0.81), RMSE (3.7 m), %RMSE (12.9), bias (0.8), %Bias (2.79) than the other models. Furthermore, the calibration response, based on a selection of four trees from the sample plots, resulted in a reduction percentage for bias and RMSE of about 1.6–2.7%. Our results indicate that the calibrated model produced the most accurate results.

Trends in Phenological Parameters and Relationship Between Land Surface Phenology and Climate Data in the Hyrcanian Forests of Iran

Vegetation activity may be changed in response to climate variability by affecting seasonality and phenological events. Monitoring of land surface phenological changes play a key role in understanding feedback of ecosystem dynamics. This study focuses on the analysis of trends in land surface phenology derived parameters using normalized difference vegetation index time series based on Global Inventory Monitoring and Mapping Studies data in the Hyrcanian forests of Iran covering the period 1981–2012. First, we applied interpolation for data reconstruction in order to remove outliers and cloud contamination in time series. Phenological parameters were retrieved by using the midpoint approach, whereas trends were estimated using the Theil–Sen approach. Correlation coefficients were evaluated from multiple linear regression between phenological parameters against temperature and precipitation time series. Significant Mann–Kendall test analysis indicate average start of season (SOS) and end of season (EOS) increased by −0.16 and +0.14 days per year, respectively. Results of significant trend analysis showed that later EOS was associated with increasing temperature trends and we found strongest relationships between temperature and phenological parameters in the west of the Hyrcanian forests, where precipitation was abundant. Moreover, SOS correlated strongly with total precipitation and mean temperature. This study allows us to better estimate the drivers affecting the vegetation dynamics in the Hyrcanian forests of Iran.

Effectiveness of sawdust and straw mulching on postharvest runoff and soil erosion of a skid trail in a mixed forest

Loss of vegetation cover by forest harvesting has increased the average surface runoff volume and sediment yield in the Hyrcanian forest in Iran. Hence, treatments are needed to mitigate the effects of skidding operations on hydrological characteristics and sediment delivery into streams. The present study evaluated the efficacy of straw and sawdust mulches in reducing soil erosion relative to untreated control plots in a severely compacted loam soil area in the Hyrcanian forest during the first year after harvesting. Immediately after skidding operations, triplicate skid trail plots received straw mulch (16.5kgm−2) sawdust mulch (2.8kgm−2) or were left untreated for the control plots (8m2). The experimental design was completely randomized; plots were randomly assigned to treatment, season, and leafless and leafed periods. The results of generalized linear modeling showed that season and treatment significantly affected the amount of runoff and sediment. Runoff was significantly lower in the summer than in the other seasons. Applying straw mulch to the skid trail decreased runoff by 36.5%, and sawdust mulch decreased runoff by 72.8% compared with the control. The straw and the sawdust mulch also decreased sediment yield by 51.9% and 94.9%, respectively. A regression analysis revealed that the runoff response to rainfall for all the treatments was linear. Also, the total measured runoff in all seasons after the straw and the sawdust mulch was less than the runoff of the control plots. However, the measured runoff in the leafless period was greater than in the leafed period. In the straw and the sawdust mulch, measured runoff in the leafless period was 91.7% and 89.8% of the total runoff, respectively. In the straw and sawdust treatment, 99.4% and 98.4%, respectively, of the sediment occurred in the leafless period. Covering the bare mineral, compacted soil on skid trails thus greatly reduces surface runoff and sediment yield.

Do we have different varieties in Acer velutinum (Sapindaceae): Morphological and molecular studies

The genus Acer L. has about 156 species which are distributed in Asia, Europe, Northern Africa and North America. The species of Acer show extensive morphological and molecular diversity and the species that co-occur may hybridize; therefore, sometimes the species delimitation turns out to be difficult. Eight Acer (maple) species have been reported in Iran. The velvet maple—Acer velutinum Boiss (1846: 28)—is one of the largest maples in the world and the most frequent maple species in Iran. Morphologically speaking, two varieties have been cited for this species. Due to the extensive morphological variability, however, the researchers encounter difficulty delimiting these two varieties. Against this backdrop, the present study was performed with the aim to delimit two varieties of Acer velutinum by using both morphological and molecular approaches. It also aimed to proffer data on the genetic diversity of this species in the country. Nighty-four plant specimens of A. velutinum were randomly collected within 14 geographical populations at four provinces in Hyrcanian forests of Iran. The PsbA-trnHGUG intergenic spacer sequence of cp-DNA and the ISSR molecular markers along with the morphometric analysis and image analysis of the leaf shape were used. The numerical and phylogenetic analyses of the tree specimens from the presumed varieties of A. velutinum—based on morphology, image analysis of leaf shape, ISSR and cp-DNA—did not delimit these varieties; hence, A. velutinum was considered to have a high level of intergrading morphological variability. The population genetic study revealed significant molecular differences among the studied populations. The STRUCTURE plot and gene flow analysis (Nm), nevertheless, revealed some degree of shared alleles among the populations. The Mantel tests demonstrated significant correlation between the geographical and genetic distance of the studied populations; it further signaled the fact that the gene flow occurred mainly between the coterminous populations.

Forest density and orchard classification in Hyrcanian forests of Iran using Landsat 8 data

Satellite-based remote sensing is of crucial importance to provide timely and continuous thematic maps for practical forestry tasks. There is currently no existing remote sensing-based, large-scale inventory of canopy cover classes (and also adjacent orchards) on the full range of Hyrcanian forests. We used the freely available and large-scale coverage of Landsat 8 imagery acquired in 2014 to classify three forest density classes as well as non-forest and orchards. The supervised classification and support vector machine classifier were selected based on a pre-classification of three representative pilot regions. Classified final maps were validated by means of a two-stage sampling and 1,852 field samples. The total areas of the dense, semi-dense, sparse forests and orchards were 45, 36, 19 and 1.9% of the total studied area, respectively. The overall accuracy and Kappa coefficient of classified maps were 94.8 and 90%, respectively. The methodology introduced to map forest cover in Hyrcanian forests is concluded to enable providing a high quality forest database for further research, planning and management.

Composition of tree species can mediate spatial variability of C and N cycles in mixed beech forests

ContextThe process of establishing a mixed canopy composition by intermingling individuals of beech, hornbeam, and maple is an ongoing trend in adaptive forest management strategies. However, our understanding of the potential of these strategies to promote forest floor and soil quality remains limited. AimsBeech (Fagus) is one of the most valuable industrial species in Iran, which is present in combination with other tree species with different effects on soil fertility. This study measures the role of different canopy compositions of beech trees, including mixed beech (beech-maple-hornbeam), beech-hornbeam, beech-maple and pure beech on forest floor quality, soil features and C and N cycles of the Hyrcanian forest in Iran. MethodsFive replicates are regarded for each canopy composition and a total of 20 permanent plots were considered in the forest. Four forest floor and soil samples, with an area of 25cm×25cm, were taken from 0 to 15cm depth under each canopy cover and a composite sample for each plot (for forest floor and soil separately) was transferred to the laboratory. Forest floor (C, N and thickness) and soil physico-chemical (water content, bulk density, aggregate stability, pH, EC, organic C, total N, available P, K, Ca and Mg), biological (earthworm biomass/density, nematode density, fine root biomass, N mineralization and basal respiration or BR), biochemical (NH4+ and NO3− concentrations, substrate induced respiration or SIR, particulate organic matter C - N or POM-C and POM-N, dissolved organic C - N or DOC and DON), soil aggregate size (macro and micro) features and soil enzyme activity (urease, acid phosphatase, arylsulphatase and invertase) were measured. ResultsMixed composition of canopy cover had the highest forest floor quality, with the greatest amount of N and the lowest of C. The highest amounts of soil aggregate stability, pH, total N and available nutrients were found in the mixed composition and the highest amounts of water content, organic C and C/N ratio, with the least of soil bulk density, were observed under pure beech. In general, higher values of earthworm density/biomass, nematode density, fine root biomass, N sequestration and mineralization, NH4+, NO3−, BR, SIR, POM-N, DON, macro aggregate, N in macro- and micro-aggregates and enzyme activity were observed in the mixed beech compared to the other canopy composition. The highest values of POM-C, DOC, C in macro- and micro-aggregates were found under pure beech canopy than in mixed beech composition. The lowest value of the C availability index (CAI) was found under pure beech canopy cover. C sequestration of different tree compositions did not show any statistically significant difference. ConclusionThe influence of trees on forest floor and soil features is detectable even in a mixed stand and the soil landscape experience a mosaic of changes, reflecting the chemical characteristics of the various tree species present in the stand. Our results suggest that the composition of tree species can change the forest floor quality, soil fertility and microbial activities related to C and N in mixed forests. As a conclusion, increasing the soil quality by tree species composition – employing hornbeam and maple for amending the forest soils with accompanying beech can be suggested in pure beech stand.

Modeling biophysical properties of broad-leaved stands in the hyrcanian forests of Iran using fused airborne laser scanner data and ultraCam-D images

Inventories of mixed broad-leaved forests of Iran mainly rely on terrestrial measurements. Due to rapid changes and disturbances and great complexity of the silvicultural systems of these multilayer forests, frequent repetition of conventional ground-based plot surveys is often cost prohibitive. Airborne laser scanning (ALS) and multispectral data offer an alternative or supplement to conventional inventories in the Hyrcanian forests of Iran. In this study, the capability of a combination of ALS and UltraCam-D data to model stand volume, tree density, and basal area using random forest (RF) algorithm was evaluated. Systematic sampling was applied to collect field plot data on a 150m×200m sampling grid within a 1100ha study area located at 36°38′- 36°42′N and 54°24′–54°25′E. A total of 308 circular plots (0.1ha) were measured for calculation of stand volume, tree density, and basal area per hectare. For each plot, a set of variables was extracted from both ALS and multispectral data. The RF algorithm was used for modeling of the biophysical properties using ALS and UltraCam-D data separately and combined. The results showed that combining the ALS data and UltraCam-D images provided a slight increase in prediction accuracy compared to separate modeling. The RMSE as percentage of the mean, the mean difference between observed and predicted values, and standard deviation of the differences using a combination of ALS data and UltraCam-D images in an independent validation at 0.1-ha plot level were 31.7%, 1.1%, and 84m3ha−1 for stand volume; 27.2%, 0.86%, and 6.5m2ha−1 for basal area, and 35.8%, −4.6%, and 77.9nha−1 for tree density, respectively. Based on the results, we conclude that fusion of ALS and UltraCam-D data may be useful for modeling of stand volume, basal area, and tree density and thus gain insights into structural characteristics in the complex Hyrcanian forests.

Comparison of the fuzzy AHP method, the spatial correlation method, and the Dong model to predict the fire high-risk areas in Hyrcanian forests of Iran

ABSTRACTThis study was done to evaluate the efficiency of three methods to predict the high-risk areas for fire in District Three of Neka Zalemroud forests located in Mazandaran Province, Iran. The fuzzy analytic hierarchy process (fuzzy AHP) and the spatial correlation method were used to model fire risk in the study area. The Dong model was used to provide the fire risk map. Following the construction of fire risk maps using three methods, the map of actual fires was overlaid to validate the used methods. Then the area of the high-risk and very high-risk classes of each fire risk map within the perimeters of actual fires was calculated. Results showed that the high-risk areas in the fire risk map prepared by the fuzzy AHP and spatial correlation methods closely follow the actual fires. On the other hand, the high-risk areas in the fire risk map prepared by the Dong model showed only a moderate agreement with actual fire areas. The final results showed that the fuzzy AHP model (accuracy 0.8) and the spatial correlation model (accuracy 0.92) have the strongest ability to predict the fire high-risk areas in Hyrcanian forests of Iran, relative to the Dong model (accuracy 0.51).

Comparison of damage to residual stand due to applying two different harvesting methods in the Hyrcanian forest of Iran: cut-to-length vs. tree length

Damage to residual stand is unavoidable and it is one of the main important issues in the forest harvesting. Trees damage may occur in felling and skidding work phase or during skid trail construction. In any case, damage can be very serious to residual stand. Detailed study is necessary to find out the amount and severity of damage to trees; therefore district 14 of Kilesara in Guilan Province, Iran was selected for the study. The cut-to-length and the tree - length methods are practiced in the Hyrcanian forest. Applying any of these two methods is mostly related to dimensions of woody material, technical characteristics of skid trail, and machinery availability. A residual stand which is left after practicing such a method, is damaged in different way which needs to be studied in detail. The length of the winching strips and skid trails differed, but the width of them was kept constant at 6 m (3 m distance from centerline of winching strips or borderline of skid trails). All trees and regenerations around winching strips and skid trails are investigated for finding any sign of damage or injuries. The results showed that along winching strips, the percentage of damage to the residual stand was 19.5 and 18 %, while the damages along skid trails reached 25.4 and 31 % in the tree length and cut-to-length methods, respectively. The results of this study suggest that damage to the residual stand is considerable and should be reduced in order to improve the quality of stand at future.

Quantitative characteristics of coliseum maple (Acer cappadocicum Gled. 1785) in relation to physiographic factors in hyrcanian forests of Iran (case study: Sangdeh, Mazandaran province)

Quantitative characteristics of coliseum maple (Acer cappadocicum Gled. 1785) in relation to physiographic factors in hyrcanian forests of Iran (case study: Sangdeh, Mazandaran province)

Application of a CA-based model to predict the fire front in Hyrcanian forests of Iran

Forest fire is one of the most important source of land degradation that lead to deforestation and desertification processes. Thus, prediction of forest fire front is necessary to control it. In this study, Alexandridis model based on Cellular Automata (CA) rules was applied to predict the fire front in a part of Hyrcanian forests of Iran. The data of effective factors on fire front in the model (including vegetation type and density, wind speed and direction, and ground elevation) were provided from Mazandaran Natural Resources Administration (MNRA), Mazandaran Meteorological Administration (MMA), and Digital Elevation Model (DEM) of ASTER sensor. The model was used to simulate the front of a wildfire that burned a part of District Three of Neka-Zalemroud forests (DTNZ) on December of 2010. The required data of actual fire for simulation of fire front (including actual fire map, fire area, fire start point, etc.) were provided from MNRA. All effective factors maps for actual fire confine were organized in a Geographic Information System (GIS). The simulation environment was provided based on the ASCII files of altitude, vegetation density, and vegetation type matrices, together with a matrix containing the burned area. The fire front model was programmed and it was implemented by uploading of all digital layers (coding ASCII matrices) of effective variables and considering of the certain wind speed and direction in fire confine. Fire front simulation was run by considering of fire start point coordination and the fire front simulation was depicted. Finally, the number of burned and unburned cells in fire confine matrix was obtained. Results of model implementation including fire front direction and shape were compared with the actual fire confine to evaluate the accuracy of the used model qualitatively. Thus, the fire front polygon was overlaid on the actual fire polygon and the high similarity was observed between them. In addition, total accuracy and Kappa index were used to evaluate the accuracy of the used model quantitatively. The total accuracy and Kappa index were obtained 0.88 and 0.74, respectively. These results can show the accuracy of CA-based model to predict the fire front in Hyrcanian forests of Iran in current research.

Effect of human-induced forest edges on the understory bird community in Hyrcanian forests in Iran: Implication for conservation and management

Understanding bird species responses to edge effect is critical for effective forest ecosystem management. We studied changes in diversity, density and abundance of bird communities and environmental variables along an edge-interior gradient in the Saadabad-Naharkhoran forested area located within the Hyrcanian forests in Iran. Bird species and environmental variables were recorded within a 25m radius of 81 sampling points. Distance from the edge had significant impact on the abundance of some species including Great Spotted Woodpecker, Nuthatch, Treecreeper and bark gleaning birds. Among diversity and evenness indices, Simpson diversity index, Shannon diversity index, and N1 and N2 indices showed significant differences. Bird species showed different density patterns in our study. Some species such as Great Tit, Nightingale, Carrion Crow and Black Bird responded positively, and Great Spotted Woodpecker, Nuthatch, Wren and Blue Tit responded negatively to forest edge conditions. Bird community analysis divided bird species into two main groups. The first group includes Pheasant, Nightingale, Jay and Blackbird which showed positive responses to edge effect and had a high correlation with variables such as ground cover, number of trees with dbh 12–20cm and temperature. The second group consisted of Treecreeper, Great Spotted Woodpecker, Green Woodpecker, and Nuthatch which showed a negative response to the edge effect and a positive correlation with snag and log dbh, snag and log height, the number of trees with dbh 100–300cm, canopy cover, life litter depth and dbh of the trees. Results obtained from this study can be important in conservation and management of bird communities in remnant Hyrcanian forests. Also, protected areas in some parts of Hyrcanian forests can be selected based on environmental variables with a positive correlation with edge-eluding species.

Generalized height-diameter models for Fagus orientalis Lipsky in Hyrcanian forest, Iran

In this study, 39 generalized height-diameter prediction models were developed for Oriental beech (Fagus orientalis Lipsky) in the Hyrcanian forest in Iran. Data were collected from 75 permanent sample plots in uneven-aged stands of F. orientalis. A total of 1,067 individual tree height-diameter measurements were available for this study. For model testing a 10-fold cross validation method was used. The goodness of fit of the models was evaluated using six statistical measures including Akaike information criteria, Bayesian information criterion, root mean square error (RMSE), mean error, R2 and R2adj. Results showed that the R2 ranged from 0.62 to 0.78 and RMSE from 3.3 to 4.7 in the validation phase. Considering all the performance criteria, a model which uses DBH, dominant height, basal area per hectare and number of trees per hectare was found to be the best model to predict the height of Oriental beech from these data.

Estimation of Forest Biomass Using Multivariate Relevance Vector Regression

The objective of this study is to develop a method based on multivariate relevance vector regression (mvrvr) as a kernel-based Bayesian model for the estimation of above-ground biomass (agb) in the Hyrcanian forests of Iran. Field AGB data from the Hyrcanian forests and multi-temporal PALSAR backscatter values are used for training and testing the methods. The results of the MVRVR method are then compared with other methods: multivariate linear regression (MLR), multilayer perceptron neural network (mlpnn), and support vector regression (svr). The MLR model showed lower values of R2 than the three other approaches. Although the SVR model was found to be more accurate than MLPNN, it had the lowest saturation point of 224.75 Mg/ha. The use of MVRVR model significantly improves the estimation of AGB (R2 = 0.90; RMSE = 32.05 Mg/ha), and the model showed a superior performance in estimating AGB with the highest saturation point (297.81 Mg/ha).