Journal of Forest Ecosystems Research

Monitoring and correlations soil parameter dynamics in Boyer-Ahmad forests

Yousef Askari

Extended Abstract

Background and Objectives: Long-term monitoring of forest soil variables is essential for assessing ecosystem dynamics, forest health, and the impacts of environmental and anthropogenic factors on soil. Key soil parameters including microbial respiration, soil moisture, organic carbon stocks, available phosphorus, and nitrogen are of strategic importance in forest ecosystems, particularly under current climate change and global warming conditions. This study pursues to measure the physical and chemical properties of the soil in the studied forest stands (in the selected fixed and permanent sample plots), and also to enable long-term monitoring of the trend of changes in the soil of these forest sites.

Materials and Methods: This study aimed to monitor soil changes and analyze correlations between soil factors in two sample plots (Parikdan= south slope and Sarabtaveh= north slope) in Boyer-Ahmad County, Kohgiluyeh and Boyer-Ahmad Province. Two randomly selected one-hectare plots (100×100 m) were inventoried, with five systematic soil samples collected from 0-30 cm depth in each plot to measure carbon, nitrogen, phosphorus, moisture, microbial respiration, bulk density, and gravel percentage. Soil data collection was repeated annually over the three-years (2018-2020) project period.
Results: The results revealed that in the Sarabtaveh site, soil organic carbon (2.94%), total nitrogen (0.26%), available phosphorus (16.21%), soil moisture (15.25%), and microbial respiration (640.88 mg CO₂/kg soil/day) were recorded, while the Parikdan site showed values of 2.85%, 0.22%, 17.57%, 15.44%, and 707.74 mg CO₂/kg soil/day, respectively. The mean soil carbon stock was estimated at 81.91 ton/ha in Sarabtaveh and 86.37 ton/ha in Parikdan.
Conclusion: Monitoring soil parameter dynamics and their interrelationships in forest ecosystems is critically important, as soil serves as the fundamental substrate that governs nutrient cycling, carbon sequestration, and biodiversity maintenance. Three-year monitoring revealed significant differences in soil carbon stock dynamics (p<0.05). In both sites, soil organic carbon demonstrated the strongest correlation (r>0.85, p<0.01) with total carbon stock, indicating its pivotal role in carbon sequestration potential. The soil moisture content, microbial respiration, and available phosphorus were significantly higher in the Parikadan sample plot compared to the Sarabtaveh plot. This difference can be attributed to the greater species diversity, higher vegetation density, and larger canopy cover in the Parikadon plot. The current study's results revealed a significant positive correlation between soil organic carbon content and total nitrogen. The increase in nitrogen mediated through changes in litter quantity and quality as well as alterations in the microbial decomposer community directly influences soil organic carbon levels.

Assessing phenological plasticity and frost resistance in three Zagros oak species using a common garden approach

Khaled Karimi hajii pamogh

Background and objectives: Cold is one of the severe and limiting environmental stresses in forest ecosystems, particularly in temperate regions. With climate change affecting plant phenology and altering cold resistance in spring and autumn (notably in seedlings), it is crucial to identify species and genotypes that exhibit resilience. Therefore, this study focused on assessing the cold tolerance of seedlings from three species: Quercus brantii, Q. infectoria, and Q. libani, and examining how this tolerance relates to their phenological traits, such as bud burst and leaf senescence.
Materials and methods: Seeds from 54 mother trees were collected from the Baneh forest region (located in the Northern Zagros, characterized by higher altitude, latitude, and colder temperatures) and sown in a communal garden in Yasuj (found in the Southern Zagros, with lower altitude, latitude, and warmer conditions) for two years. Various phenological parameters (including the timing, rate, and speed of leaf bud burst and leaf senescence) as well as survival rates and damage of the terminal bud of the seedlings were recorded and analyzed at different time intervals using statistical methods such as repeated measures analysis of variance, Duncan's test, and Pearson correlation.
Results: The results of this research indicated that seedlings of different oak species exhibit notable differences in leaf bud burst speed, damage to seedlings, and survival rates. Specifically, the Q. brantii opened its buds approximately 3-4 days earlier and more rapidly, while, it showed the least damage to the terminal bud and the highest survival rate. In contrast, the Q. infectoria opened its buds later and more slowly than other species and suffered the most damage to the terminal bud and had the lowest survival rate. Additionally, correlation analysis revealed that seedlings with faster bud opening in the early growing season tend to have more terminal bud damage but also higher survival rates. Furthermore, the results of leaf senescence also showed that there was no significant difference among the three species in two years, although a positive correlation between the speed of bud burst and the leaf senescence.
Conclusion: The findings of this research suggest that the Q. brantii exhibits greater resistance to late spring frosts due to its favorable phenology (earlier and faster bud burst) and reduced bud susceptibility to cold. Consequently, it is less affected by late spring frosts associated with climate change compared to the other two species studied. Therefore, it is recommended to planted the Q. infectoria and Q. libani species more in the higher and cooler regions of the Zagros, and to select seeds from genotypes that have a later bud burst in spring for breeding programs.

Estimation of Carbon Storage of Tree Cover in Urban Forest (Study area: Mazandaran Province, Sari City)

Elham Fazeli

Extended Abstract
Background and Objectives: One of the most important factors of global warming is the phenomenon of illegal emission of greenhouse gases; The most important of which are nitrogen dioxide (NO2), carbon dioxide (CO2), and methane (CH4). However, due to the large amount of carbon dioxide accumulation in the atmosphere, this gas is one of the key gases in the phenomenon of global warming. Therefore, to reduce atmospheric carbon dioxide and balance the content of greenhouse gases, atmospheric carbon must be absorbed and deposited in various forms. Urban forests have a high capacity to absorb atmospheric carbon dioxide and provide many environmental services in urban areas. Therefore, it is necessary to obtain correct and accurate information in this regard to optimally manage these forests in increasing carbon sequestration. This research aimed to estimate the amount of carbon stock of the urban forest in Sari City, the capital of Mazandaran province.
Materials and methods: This research Using selective sampling, 150 samples were taken (50 samples in each region) and an effort was made to distribute these samples in the three regions. First, the information related to the general characteristics of each of the samples, including the height above sea level, the slope, and the direction of measurement, were recorded. In each sample plot, species type, breast diameter, height, and small and large crown diameters of all trees were measured, and the number of each tree and shrub species was counted and harvested. The center of each sample and measured tree was recorded with a GPS device and transferred to the GIS software environment. After calculating the carbon sequestration of trees, the relationship between diameter and carbon sequestration was investigated using linear regression in SPSS software version 21. Then, a carbon sequestration zoning map was prepared in all areas of Sari using the conventional kriging method and in GS+ software.
Results: The highest and lowest amount of carbon sequestration of trees was observed in areas one (60.95 ± 31.10 tons per hectare) and three (13.68 ± 3.84 tons per hectare) of Sari city, respectively. Variance analysis of diameter and carbon deposition relationships showed that linear and power regression models were significant. The evaluation results of the linear regression model (R2=0.74) and power (R2=0.97) showed that both models are highly accurate in estimating carbon deposition on the ground of trees. According to the results, the highest potential of carbon sequestration was observed in the northeastern part and located in an area of Sari.
Conclusion: In this research, a high amount of carbon sequestration was observed in the city of Sari. It can be said that the main reason for the high amount of carbon deposition in Sari city is that, most of the trees in the green space of Sari city are old plane trees The reason for the high level of carbon deposition of the plantain tree is the high density of its wood compared to other trees. In general, young trees have a higher amount and speed of carbon deposition than old trees, but old trees also deposit carbon in a larger amount and for a longer period. Obtaining the results that the trees of Sari city can absorb 200 tons of carbon per hectare is remarkable and promising. Prioritizing the preservation and growth of larger and older trees in urban environments may have significant results for carbon sequestration. At the same time, examining the temporal dynamics of carbon sequestration, combining other environmental variables, or modifying the spatial resolution of the analysis can further increase the accuracy of carbon sequestration estimation. Therefore, obtaining more information in this direction is necessary and necessary.

Effects of the Shelterwood System on Changes in Aboveground Biomass of Beech Forest Trees

Hashem Habashi

Background and objectives: The Hyrcanian forests play a crucial role in carbon storage, soil and water conservation, and climate change mitigation. Previous studies on the silvicultural management of these forests have mainly focused on estimating stand volume and structural characteristics, while the impacts of different management regimes—particularly the shelterwood system—on aboveground biomass, as a key indicator of carbon sequestration, remain unclear. The main objective of this study was to quantify and analyze the effects of shelterwood management treatments on tree quantitative characteristics and aboveground biomass in the beech (Fagus orientalis Lipsky) forests of Kelardasht, northern Iran.
Materials and methods: The research was conducted in Compartment 5 of the Kelardasht forest management plan. Five management treatments were selected: control, shelterwood, partial shelterwood, shelterwood with improvement cutting, and unmanaged (outside the management plan). In each treatment, five 0.5-hectare plots were randomly established. Diameter at breast height (DBH), total height, and stem height were measured, and tree volume was calculated. Aboveground biomass was estimated using tree volume, wood specific gravity, and FAO expansion factors. Data were analyzed using one-way ANOVA and independent t-tests.
Results: Mean DBH and total height were significantly higher in unmanaged treatments (control and outside the management plan) than in managed ones. The control treatment had the highest aboveground biomass (613.58 t ha⁻¹), whereas the complete shelterwood treatment had the lowest (272.56 t ha⁻¹), representing a 56% reduction compared to the control. The partial shelterwood and shelterwood with improvement cutting treatments had mean values of 417.13 and 273.61 t ha⁻¹, respectively. These patterns were consistent with structural indices such as stand volume and total height; even-aged stands resulting from complete shelterwood had lower biomass, while uneven-aged structures in partial shelterwood and control treatments performed better.
Conclusion: The findings suggest that the partial shelterwood method is a suitable option for the mid-elevation forests of Kelardasht, as it combines considerable economic benefits with biomass levels closest to the control treatment, while maintaining the advantages of uneven-aged forest structures. For the first time, this study demonstrates that prolonging the shelterwood regeneration period can lead to the formation of natural, uneven-aged stands that exhibit features of sustainable forests, with important implications for enhancing carbon sequestration in these valuable Hyrcanian ecosystems.

Modeling the Relationship Between Climatic Fluctuations and Diameter Growth of Pistacia atlantica in Zagros Forests Using Neural Network

Ali Mahdavi

Extended Abstract

Background and Objectives: Climate change, manifested through fluctuations in key variables such as temperature and precipitation, poses a significant threat to forest ecosystems, particularly in semi-arid regions like the Zagros. Pistacia atlantica (Wild Pistachio) is a valuable native species in these forests, whose growth is highly sensitive to water availability. Quantifying the impact of climatic variables on its radial growth is essential for adaptive forest management. While traditional statistical methods have been used, advanced artificial intelligence models like the Group Method of Data Handling (GMDH) neural network offer superior capabilities for modeling complex, non-linear relationships. The main objectives of this study were to: 1) evaluate the effect of climatic variables (precipitation, temperature, relative humidity) on the diameter growth of P. atlantica, 2) determine the most influential climatic factors, and 3) assess the accuracy of the GMDH neural network model in predicting growth based on climate data.

Materials and Methods: The study was conducted in three habitats of P. atlantica (Darreh Shahr, Abdanan, and Majin) in Ilam province, Iran. A total of 18 tree discs (6 from each site, divided into two diameter classes: <30 cm and >30 cm) were collected from trees with similar topographic conditions. After surface preparation and polishing, high-resolution images were taken, and annual ring widths were precisely measured using Motic image software. Wood density was also determined for each sample. Climatic data (annual precipitation, average, minimum, and maximum temperature, relative humidity) for the past 15 years were obtained from the nearest meteorological stations. The relationship between ring width indices and climatic variables was first analyzed using Pearson correlation in SPSS software. Subsequently, the GMDH neural network model was implemented in MATLAB (R2014a) to predict radial growth based on climatic inputs. The data were randomly divided into training (70%), validation (15%), and test (15%) sets. Model performance was evaluated using statistical indices: Root Mean Square Error (RMSE), Mean Square Error (MSE), and Correlation Coefficient (R).
Results: Statistical analysis revealed a significant positive correlation between annual ring width and both annual precipitation (r = 0.188, p=0.002) and relative humidity (r = 0.173, p=0.004). In contrast, a significant negative correlation was found with average annual temperature (r = -0.185, p=0.002) and maximum annual temperature (r = -0.152, p=0.013). No significant correlation was observed with minimum annual temperature. The GMDH neural network model demonstrated high accuracy in predicting radial growth from climatic variables, with performance metrics on the total dataset as follows: RMSE = 3.86, MSE = 14.88, and R = 0.90. The model's predictions closely matched the observed growth trends, confirming its effectiveness.
Conclusion: The radial growth of Pistacia atlantica in the semi-arid Zagros forests is significantly influenced by climatic fluctuations. Increased precipitation and relative humidity positively enhance growth, while rising temperatures, particularly maximum temperatures, have a suppressive effect, likely due to increased evapotranspiration and water stress. The successful application of the GMDH neural network model, with its high predictive accuracy (R=0.90), establishes it as a powerful and reliable tool for modeling climate-growth relationships in complex forest ecosystems. These findings provide critical insights for developing climate-adaptive conservation and management strategies to enhance the resilience of P. atlantica stands against future climate variability.

Floristic Composition of the Understory Vegetation in Different Persian Oak (Quercus brantii Lindl.) Stands: A Case Study of the Ghlajeh Forests, Kermanshah Province

Kambiz abrarivajari

Background and objectives: Background and objectives: Understory vegetation in forests directly interacts with the type and ecological conditions of forest stands and plays a vital role in maintaining ecological balance. Therefore, identifying and studying the flora of the understory is essential. This study aimed to investigate and identify the similarities and differences in plant species, their life forms, and chorological characteristics in different Persian oak stands within the protected forests of Ghalaje, Kermanshah Province.
Materials and methods: The forest stands were categorized based on their regeneration forms (high stand, coppice stand, and high–coppice stand). Subsequently, in each stand, three one-hectare sample plots were randomly established. The structural attributes of all trees and coppice groups were measured and recorded, including species identity, growth form, number of sprouts per coppice group, diameter at breast height (DBH), tree height, dominant height of coppice groups, and two perpendicular crown diameters. For the assessment of understory vegetation, ten 100 m² subplots were randomly selected within each main plot, and four 1 m² quadrats were established at the corners of each subplot.
Results: The results showed that a total of 146 vascular plant species belonging to 35 families and 104 genera were identified in the understory. Of these, 124 species from 33 families and 88 genera were found in coppice stands, 103 species from 31 families and 83 genera in high–coppice stands, and 108 species from 33 families and 83 genera in high stands. Analysis of life forms using Raunkiaer’s method indicated that therophytes were dominant in all three stands, while phanerophytes had the lowest representation. In all stands, dicotyledons constituted more than 75% of the plant species. Chorological analysis using Zohary’s approach showed that, in coppice, seed–coppice, and seed-origin stands, respectively 25%, 25.71%, and 30% of the species belonged to the Irano-Turanian region; 30.6%, 30.5%, and 32.7% occurred in two phytogeographical regions; 20.9%, 22.8%, and 16.8% occurred in three regions; and 22.5%, 20%, and 21.6% were multi-regional elements. Cosmopolitan species accounted for less than 1% in all three stands. Overall, the findings suggest that the Persian oak stands in the study area show no considerable differences in species richness, life-form composition, phytogeographical distribution, or family representation.
Conclusion: Overall, the results indicate that the differences in floristic composition, life-form structure, and sub-canopy chorological patterns among the different oak stands in the Ghalajeh Protected Area reflect habitat homogeneity and the relative stability of ecological conditions in the region. The dominance of therophytes across all stands demonstrates the vegetation’s adaptation to dry and semi-arid climatic conditions and seasonal fluctuations. This feature can also serve as an indicator of the ecosystem’s response to environmental stress, and this dominance was higher in the coppice stands than in the other stands.

Evaluating the Role of Spectral Library–Derived Indices in Improving Forest Type Classification in the Central Zagros Using Sentinel-2 Imagery

Hamid Reza Riyahi Bakhtyari

Background and objectives: The Zagros forests, one of Iran's natural ecosystems, possess significant ecological diversity, and understanding their typology is crucial for sustainable management. The forests of Flard County in Chaharmahal and Bakhtiari Province, primarily covered by oak (Quercus brantii) and pistachio (Pistacia mutica), are part of the central Zagros region. These forests play a prominent role in ecological sustainability, biodiversity conservation, and providing environmental services. However, the lack of current and accurate typological maps has hindered their scientific management. Traditional ground-based survey methods are inefficient due to high costs and difficult terrain. This study aimed to use modern remote sensing technologies and evaluate how spectral indices derived from a spectral library improve the accuracy of supervised classification of Sentinel-2 satellite imagery for discriminating forest types.
Materials and methods: To investigate the impact of spectral indices derived from the spectral library on distinguishing the region's dominant species, this study was conducted in three forest areas: two pure types and one mixed type. These areas were Mishan (pure oak), Kate-Siah (pure pistachio), and Vandun (mixed oak-pistachio cover) in Flard County, Chaharmahal and Bakhtiari Province. Three different classification scenarios were used. In Scenario 1, only Sentinel-2 images from October 15, 2024, were classified for all three study areas. In Scenario 2, in addition to the sensor's main bands, general spectral indices—NDVI, SAVI, MSAVI, GNDVI, and EVI—were applied to the Sentinel-2 data and incorporated into the classification process. These indices, respectively, assess greenness, reduce soil background effects, measure chlorophyll health, and enhance sensitivity to dense canopies. In Scenario 3, besides the main bands, specialized spectral indices—PRI, CRI, MCRI, CAI, NDVI800, NPCI, RENDVI, and ARI—extracted from the spectral library data of the oak and pistachio species were included in the classification process. Data classification in all three areas was performed using three supervised algorithms: Support Vector Machine (SVM), Maximum Likelihood Classification (MLC), and Minimum Distance (MinDist).
Accuracy was assessed using a ground truth map, the Kappa coefficient, and overall accuracy criteria.
Results: Results indicated that in Scenario 1, the Maximum Likelihood Classification (MLC) algorithm performed best with overall accuracies and Kappa coefficients of 98.4% and 0.71 in Mishan, 77.5% and 0.32 in Kate-Siah, and 86.7% and 0.67 in Vandun, respectively. In Scenario 2, the same algorithm was best in Mishan (97.7% overall accuracy, 0.65 Kappa coefficient) and Kate-Siah (75.9% overall accuracy, 0.38 Kappa coefficient). However, in Vandun, the SVM algorithm was superior, achieving an overall accuracy of 77.9% and a Kappa coefficient of 0.57. In Scenario 3, accuracy assessment results demonstrated that the SVM algorithm reported the highest accuracy in all three regions: Mishan (99.2% overall accuracy, 0.81 Kappa coefficient), Kate-Siah (98.2% overall accuracy, 0.74 Kappa coefficient), and Vandun (89.0% overall accuracy, 0.67 Kappa coefficient). A comparison of the three scenarios showed that specialized spectral indices derived from the spectral library were more effective in increasing classification accuracy than general indices. Despite the high accuracy of the algorithms, limitations such as spectral similarity between soil and vegetation in low-density areas affected the results.
Conclusion: Based on these findings, integrating valid spectral data with machine learning algorithms is an effective tool for preparing detailed forest cover maps. Using a spectral library alongside Sentinel-2 imagery enables more accurate discrimination of forest. The SVM algorithm is a suitable option for classifying forest types in areas with dense cover and complex structures. The findings of this research are applicable to conservation-management planning and the continuous monitoring of Zagros Forest ecosystems.

Assessing floristic composition, plant life forms, and species diversity patterns across diverse forest–rangeland management regimes in Bashgol, Qazvin

Ghasemali Dianati tilaki

Background and objectives: Managing forest-rangeland ecosystem management and afforestation are crucial for shaping species composition, establishment, and ecosystem resilience, extending beyond mere wood or biomass production. In arid and semi-arid regions, the combined effects of grazing, water scarcity, and restoration interventions create synergistic impacts. This study investigated how these factors influence understory cover, floristic composition, life forms, and diversity indices in afforestation stands and forest habitats under various management regimes in Bashgol, Qazvin.
Materials and methods: The study was conducted in the forest-rangeland habitats of Bashgol, Qazvin Province (Central Alborz). To minimize environmental heterogeneity, sites were selected at elevations between 1480–1550 m a.s.l. and with slopes less than 10%. Five management regimes were evaluated: afforestation, exclosure, pit-seeding, light grazing, and heavy grazing. For each regime, three 100-meter transects were established, with a total of 75 plots surveyed (15 plots per regime). Along each transect, ten 1.5 m² quadrats were demarcated, and five were randomly selected for detailed measurement. Within each selected plot, cover percentage, floristic composition, and life forms were recorded. Shannon–Wiener, Simpson, Margalef, Menhinick, evenness, and alpha and beta diversity indices were calculated. These indices were then compared using analysis of variance (ANOVA) and Duncan's test.
Results: Floristic analysis revealed that perennial species constituted the dominant component of the community, accounting for 77.63% of the total cover, while annual plants accounted for 22.37%. Among the evaluated regimes, complete exclosure exhibited the highest canopy cover (73%). Despite having lower overall vegetation cover, afforestation resulted in superior diversity metrics, achieving the highest Shannon–Wiener (1.31) and Simpson (0.38) indices. Conversely, heavy grazing recorded the lowest values for both indices (0.29 and 0.14, respectively), with these treatment differences being statistically significant. Margalef richness was also significantly influenced by management, with exclosure, afforestation, and light grazing maintaining higher richness, while heavy grazing showed the lowest. In contrast, Menhinick richness peaked under light grazing. The highest alpha (α)-diversity was observed under light grazing (2.56), whereas the lowest occurred under pit-seeding (0.63). Beta diversity reached its maximum in afforestation (0.69) and its minimum in exclosure (0.35). ANOVA confirmed that the management regime had a significant effect on both alpha and beta diversity.
Conclusion: The dominance of perennial species suggests ecological stability, while the presence of annual plants indicates responsiveness to environmental stress. Exclosure, by eliminating grazing and trampling, resulted in the highest vegetation cover. Afforestation, through the creation of microclimatic heterogeneity, fostered the highest beta diversity. The superior richness and alpha diversity observed under light grazing, coupled with their severe decline under heavy grazing, supports the Intermediate Disturbance Hypothesis. No single management regime optimized all indices simultaneously; therefore, the specific objectives of each site should guide the management approach. Heavy grazing leads to undesirable consequences, and a combination of rotational exclosures, controlled light grazing, and low-impact afforestation is recommended.

The effect of the seed weight of chestnut-leaved oak (Quercus castaneifolia) on the growth, survival and quality index of produced seedlings

Seyed Mohsen Hosseini

In the present study, the effect of the seed weight of chestnut-leaved oak on the growth, survival and seed quality index of the produced seedlings was investigated. 800 oak seeds were collected from the branches facing the light in the middle part of the crown of a mature tree in Tamishan Noor region. The collected seeds were classified into four classes including the weight of each seed less than 4 g, 4 to 6 g, 6 to 8 g and more than 8 g. 400 seeds from the above collection were placed in the germinator after dividing into four seed-weight-classes in the laboratory in order to compare the germination percentage. The remaining 400 seeds were planted as four weight classes, including 100 seeds in each class, in nursery of Koloudeh Amol. The results showed that the percentage of seed germination did not have a significant difference among the treatments. However, the seedlings produced from larger seeds reached a higher seedling height at even 3 months and 8 months, and had a larger collar diameter than that, being statistically different. The percentage of survival was also higher in the seedlings obtained from larger oak seeds. Meanwhile, the SQ seedling quality index did not show a statistically significant difference among various seed weight treatments. Since the planting of taller and thicker seedlings has more successful results in terms of competition with invasive plants in the gaps and considering their higher survival percentage, it can be recommended using larger seeds of chestnut-leaved oak in seeding, seedling production in nurseries and planting in forest fields to produce tall oak seedlings.

Assessment of forest road condition after a logging ban in the Kelardasht forestry plan

Ata ollah Hosseini

Background and Objectives: Forest roads are critical infrastructure for forest management, conservation, and access. During periods when forest management activities and timber harvesting are suspended, the maintenance of existing roads may decline. However, a road's condition is not solely dependent on the cessation of harvesting; factors such as longitudinal slope, drainage, road geometry, soil properties, rainfall, road age, initial construction quality, and traffic also contribute to its deterioration. Therefore, this study aimed to descriptively compare quantitative and qualitative indicators of road condition across two longitudinal slope classes (>7% and <5%) on a secondary forest road within the Kelardasht Forestry Plan, located in the Hyrcanian forests. The primary objective was to evaluate the effect of slope magnitude on the degradation and deterioration of forest road pavement during a logging-ban period.
Materials and Methods: Eight road segments were investigated, each situated between two consecutive cross culverts. Four segments were in the less than 5% slope class, and four were in the greater than 7% slope class. Field data collected included the longitudinal slope of each segment and the condition of culverts, side ditches, road surface, and cut-and-fill slopes. Quantitative variables for each class were summarized using the arithmetic mean, while categorical variables were reported descriptively.
Results: In segments with a slope greater than 7%, a higher frequency of road surface degradation indicators, culvert blockage, side ditch malfunction, and cut slope instability was observed. The mean longitudinal slope was 7.75% in the greater than 7% class and 2% in the less than 5% class. The mean cross slope was 4.75% and 2.5%, respectively. Signs of erosion were observed below the culvert outlet in all segments of both classes. Culverts on slopes greater than 7%, along with cut slopes, had a more significant impact on erosion and side ditch blockage, consequently increasing runoff on the road surface, which led to the formation of potholes and the loss of surfacing material.
Conclusion: While signs of road degradation were observed in both slope classes, the frequency of certain degradation indicators was higher in segments with slopes greater than 7%. These results highlight the necessity of regular monitoring and maintenance of culverts, side ditches, road surfaces, and cut-and-fill slopes. Adequate and urgent budget allocation for the maintenance and repair of existing roads is essential. This study's novelty lies in its integrated recording of indicators for road surface, drainage, culverts, and cut-and-fill slopes across defined longitudinal slope classes. The resulting checklist can serve as a practical basis for subsequent monitoring and for identifying segments in need of repair and maintenance.