Yazar "Ozcan, Mehmet" seçeneğine göre listele
Listeleniyor 1 - 5 / 5
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Determining plant species diversity of Scots pine stands in the Bolu Aladag region of Turkiye(Univ Austral Chile, Fac Ciencias Forestales, 2023) Gurkan, Mustafa; Zengin, Hayati; Ozcan, Mehmet; Degermenci, Ahmet Salih; Aksoy, NecmiThis study aims to determine how plant diversity changes at the alpha and gamma levels depending on stand type. Also, it tries to understand how plant diversity changes temporally and with relation to aspects during a given vegetation period. Sample areas were selected from pure Scots Pine stands with full canopy cover (70 - 100 %) and in different development stages (a, b, c, d) spread out within the Bolu Aladag region of Turkiye. Field studies were carried out in 2016 from June-September. Sample stands were selected to cover two main aspects, north and south. The study was carried out by analyzing two repetitive and 10 quadrate samples in each stand. A total of 640 quadrate samples were analyzed, and the different plants were counted. In the study area, a total of 160 taxa were identified at the DUOF Herbarium. It was determined that while the stand type did not have a significant effect on taxon diversity, the effect of aspect and observation period was statistically significant (P < 0.05). Shannon index value was between 3.13 and 3.72 among the stands' different development stages, with the highest values found in the young stands. Diversity was higher on Northern aspects than Southern and rose and fell throughout the observation period with the highest values in June and August. Interestingly, while there was no significant effect of stand development stages on taxon diversity, a significant but low correlation has been found between stand diameter and evenness.Öğe Effect of different soil conservation methods and planting with four-wing salt bush (Atriplex canescens) on soil erosion in a semi-arid region of Turkey(Univ Austral Chile, Fac Ciencias Forestales, 2020) Sahin, Ugur; Ozcan, MehmetThis study was conducted to evaluate whether the four-wing salt bush plant (A triplex canescens) can be used to prevent erosion on the areas with steep slopes with semi-arid conditions by applying different soil conservation methods and planting spaces in a semiarid region of Turkey. For this purpose, eight treatments with three replications (20 m(2) plots) were established in the study site to measure amount of runoff and soil loss after precipitation events in 2015 and 2016, where vegetation cover was completely removed by spraying herbicide. Planting holes and terraces were established and half of them were planted with saplings of Atriplex canescens with different planting spaces (3 m interval, 0.5 and 1 m distances) to determine if different soil conservation types or combination of them with planting have any impact on soil loss and surface runoff. The results suggested that soil loss and surface runoff in eight treatment plots were higher in 2015 compared to 2016. The highest soil loss was 0.42 Mg ha(-1) in the control treatment, while the lowest was 0.11 Mg ha(-1) with cultivation with terrace + 50 cm of A. canescens in 2015. The total surface runoff was 4.66 mm in the control in 2015 whereas it was 2.33 mm in terracing + planting of A. canescens at 50 cm spacing. The combined treatment (terrace with planting of A. canescens at 50 cm distance) seems to be the best method to decrease surface runoff and erosion compared to the other treatments employed on the slopes (43 %) in Eskisehir.Öğe EVALUATION OF THE EFFECTS OF SOME WATERSHED CHARACTERISTICS ON WATER AND SUSPENDED SEDIMENT YIELD IN AGRICULTURAL AND FOREST DOMINATED WATERSHEDS(Croatian Forestry Soc, 2021) Citgez, Tarik; Karagul, Refik; Ozcan, MehmetTopography, geological structure and land use play a determinative role in the streamflow and total suspended sediment yield of watersheds having similar climate, soil and vegetation characteristics. In order to facilitate sustainable water resource management and effective land use planning, there is an increasing need for research investigating the effects of these factors. This study was carried out in forested and agricultural dominated sub-watersheds of the Big Melen watershed in the Western Black Sea Region of Turkey. Hazelnut plantations are grown on most of the agricultural areas in both watersheds. The forested watershed has a steep topography and its geological structure consists of sandstone-mudstone and sedimentary rock. The agricultural watershed area is larger and unlike the forested watershed, there is argillaceous limestone in its geological structure. The precipitation, streamflow and total suspended sediment yield in the watersheds were measured for two years. The total precipitation of the study area over the two years was 2217.3 mm. The water yield of the forested watershed was 867.6 mm, while that of the agricultural watershed was 654.9 mm. In the two years, the total suspended sediment transported from the forested watershed was 19.51 t ha(-1) and from the agricultural watershed 7.70 t ha(-1). However, except for the high values measured after an extreme rainfall event, the unit surface suspended sediment yield of the agricultural watershed was found to be higher than that of the forested watershed. These findings showed that watershed characteristics such as slope, geological structure and rainfall intensity may be more effective on the streamflow and total suspended sediment yield of the watersheds than land use.Öğe Investigation of changes in leaf area ındex in different forest stands(Springer, 2025) Degermenci, Ahmet Salih; Zengin, Hayati; Ozcan, Mehmet; Citgez, TarikLeaf area & imath;ndex (LAI) is a fundamental metric of forest canopy structure, driving photosynthetic capacity, carbon sequestration, and ecosystem productivity. In this study, we quantified LAI variation across six forest stand types (pure fir, pure beech, pure Scots pine, mixed coniferous, mixed deciduous, and mixed deciduous-coniferous) and six developmental stages in the D & uuml;zce region of Turkey, an area characterized by mixed, heterogeneous woodlands. Field measurements from 260 systematically distributed sample plots collected in 2015 employed hemispherical photography for LAI, the N-tree method for basal area (BA) and diameter at breast height (DBH), and atmospherically corrected Landsat 8 OLI imagery for NDVI. Descriptive analyses revealed LAI values ranging from 0.36 m(2)/m(2) in pure Scots pine to 6.30 m(2)/m(2) in mixed deciduous stands. One-way ANOVA and Duncan's multiple-range tests confirmed significant differences among stand types (p < 0.01), with mixed and vertically stratified stands exhibiting the highest LAI. Developmental stages showed increasing mean LAI trends from juvenile (ab) to mature (d) classes, though stage-only ANOVA was not significant (p = 0.378) due to high within-stage variability (CV approximate to 31%). Pearson correlations indicated moderate positive relationships between LAI and both DBH (r = 0.49) and BA (r = 0.53), whereas NDVI displayed the strongest association (r = 0.75 overall; up to r = 0.80 in mixed stands). A multiple linear regression model integrating NDVI, DBH, and BA explained 60.6% of LAI variance (F = 129.7, p < 0.001; adjusted R-2 = 0.601), with NDVI emerging as the dominant predictor (standardized beta = 0.683), followed by DBH (beta = 0.326) and BA (beta = 0.187). These findings underscore the complementary value of integrating spectral indices and structural parameters in the estimation of LAI, particularly in heterogeneous forest stands. The structural complexity of mixed stands appears to play a critical role in enhancing canopy development. To improve estimation accuracy in conifer-dominated or high-LAI forests, future studies should consider incorporating alternative vegetation indices and LiDAR-derived structural metrics to overcome limitations such as spectral saturation and insufficient vertical resolution. Such integrated approaches can significantly enhance the scalability and cost-effectiveness of forest health and productivity monitoring efforts.Öğe Multiple linear regression models for the estimation of water flows for forest management and planning in Turkiye(Water Research Commission, 2023) Zengin, Hayati; Ozcan, Mehmet; Degermenci, Ahmet Salih; Citgez, TarikWhile there are many factors, including climatology, geography, topography, vegetation and soil, that affect hydrologic processes, understanding the role of forests seems most essential, due to their manageable nature. In this study, a holistic approach was taken, and possible factors affecting streamflow, including tree, sapling, shrub, herb and soil strata, were measured for 29 small catchments/stream basins located in Turkey. Linear regression models were developed in order to estimate water flow (m3 & BULL;ha-1). Several models were suggested for use in practice. These models were based on the data on hand and displayed a sufficient level of explained variance in the dependent variable. Model 5, based on the variables of catchment area (ha), drainage density, ratio of coniferous stand areas in the catchment (%), tree volume (m3 & BULL;ha-1), leaf area index, number of short saplings (number & BULL;ha-1), and topsoil sand rate (%), was recommended for flow estimation, achieving a 0.73 adjR2 value for test data. These variables can be obtained as part of a survey and water managers can use them to estimate water flow of the catchment. The generated models can be used in multiple-use planning of forests, e.g. in adjusting the volume of stands to get optimum benefit from wood and water production. One of the most interesting results and one that was opposite to that documented in the general literature, was the positive correlation between tree volume and flow per hectare, which suggests a strategy of growing older tree stands to enable greater water production.
