No abstract

Korunan alanlar yeryüzündeki biyolojik çeşitliliğin korunmasında en etkin mekanizmalardan biridir. Korunan alanların sürdürülebilir bir şekilde yönetilmesi, barındırdığı habitat tipleri ve ekolojik yapının devamlılığının sağlanması için alanda geçmişten günümüze yaşanan değişimin sistematik bir şekilde izlenip değerlendirilmesi gerekmektedir. Bu çalışma, Karagöl-Sahara Milli Parkı'ndaki habitat yapısının zamansal ve ekolojik bakımdan ne ölçüde değiştiğini ölçmek ve değişimin ne yönde ilerlediğini ortaya koymak amacıyla parça, sınıf ve tüm alan düzeyinde parçalılık analizi ve fragmantasyon indeksleri yardımıyla gerçekleştirilmiştir. Bu amaçla, veri kaynağı olarak 1971 ve 1984 yıllarına ait memleket paftaları, 1984 ve 2015 yıllarına ait meşcere haritaları ve 2015 yılına ait dijital renkli kızıl ötesi hava fotoğraflarından yararlanılmıştır. Sahadaki ekolojik yapının 45 yıllık değişimi çekirdek alan (MCA), parça yoğunluğu (PD), ortalama parça büyüklüğü (MPS), ortalama şekil indisi (MSI), ortalama en yakın komşuluk mesafesi (MNN) ve karışım-dizilim (IJI) indisleri kullanılarak CBS ortamında analiz edilmiştir. Analiz sonuçlarına göre toplam orman alanlarının (verimli+bozuk) 1971'den 1984 yılına kadar %3 oranında düşüş gösterdiği, 1984 yılından 2015 yılına kadar bu düşüşün % 12 oranında devam ettiği görülmüştür. Orman alanlarındaki bu habitat kaybının doğal afetler sonucunda orman içi açıklıklara dönüştüğü, OT alanlarındaki son 45 yılda meydana gelen % 40 artış ile açıklanabilir. Diğer taraftan 1984 yılında sırasıyla 30 ve 221 ha genişliğinde olan iskân ve ziraat alanları, çoğunlukla bozuk ve verimli ormana dönüşerek 2015 yılında 20 ve 158 ha'a inmiştir. İskân ve ziraat alanlarındaki bu gerileme, 1980'li yıllarda hızlanmaya başlayan kırdan kente göç sonucu özellikle genç nüfusun tarım arazilerini terk etmesiyle ilişkilendirilmiştir. Kullanılan indis sonuçları en fazla fragmantasyona uğrayan sınıfın bozuk orman sahaları olduğu, bunu ziraat sahalarının izlediğini göstermektedir. MCA/MSI oran sonuçları ziraat alanlarındaki kenar parçalanmasının ortalama çekirdek alan büyüklüğüne en fazla etki eden sınıf olduğunu göstermiştir. Fragmantasyonun artması ormancılık sektörü açısından olumsuz olarak değerlendirilebileceği gibi, bölgede kenar etkisine ihtiyaç duyan bazı yaban hayatı türleri için fırsat olarak da değerlendirilmelidir. Sonuç olarak habitat parçalanmasının farkındalığı uzun yıllar aldığından, bölgedeki her habitat türüne has ağaç, bitki, memeli, kuş ve sürüngenlerden oluşan gösterge türler belirlenmeli ve habitat kayıpları etkin bir korunan alan yönetimi için bu türler yardımıyla da izlenmelidir.

Recent advances in LiDAR sensors and robotic technologies have raised the question of whether handheld mobile laser scanning (HMLS) systems can allow for the performing of forest inventories (FIs) without the use of conventional ground measurement (CGM) techniques. However, the reliability of such an approach for forest planning applications, particularly in non-uniform forests under mountainous conditions, remains underexplored. This study aims to address these issues by assessing the accuracy of HMLS-derived data based on the calculation of basic forest attributes such as the number of trees, dominant height and basal area. To this end, near-natural forests of a national park (NE Türkiye) were surveyed using the HMLS and CGM techniques for a management plan renewal project. Taking CGM results as reference, we compared each forest attribute pair based on two datasets collected from 39 sample plots at the forest (landscape) scale. Diameter distributions and the influence of stand characteristics on HMLS data accuracy were also analyzed at the plot scale. The statistical results showed no significant difference between the two datasets for any investigated forest attributes (P > 0.05). The most and the least accurately calculated attributes were quadratic mean diameter (root mean square error (RMSE) = 1.3 cm, 4.5 per cent) and stand volume (RMSE = 93.7 m3 ha−1, 16.4 per cent), respectively. The stand volume bias was minimal at the forest scale (15.65 m3 ha−1, 3.11 per cent), but the relative bias increased to 72.1 per cent in a mixed forest plot with many small and multiple-stemmed trees. On the other hand, a strong negative relationship was detected between stand maturation and estimation errors. The accuracy of HMLS data considerably improved with increased mean diameter, basal area and stand volume values. Eventually, we conclude that many forest attributes can be quantified using HMLS at an accuracy level required by forest planning and management-related decision making. However, there is still a need for CGM in FIs to capture qualitative attributes, such as species mix and stem quality.

Forest ecosystems play a crucial role in mitigating global climate change by forming massive carbon sinks. Their carbon stocks and stock changes need to be quantified for carbon budget balancing and international reporting schemes. However, direct sampling and biomass weighing may not always be possible for quantification studies conducted in large forests. In these cases, indirect methods that use forest inventory information combined with remote sensing data can be beneficial. Synthetic aperture radar (SAR) images offer numerous opportunities to researchers as freely distributed remote sensing data. This study aims to estimate the amount of total carbon stock (TCS) in forested lands of the Kizildag Forest Enterprise. To this end, the actual storage capacities of five carbon pools, i.e. above- and below-ground, deadwood, litter, and soil, were calculated using the indirect method based on ground measurements of 264 forest inventory plots. They were then associated with the backscattered values from Sentinel-1 and ALOS-2 PALSAR-2 data in a Geographical Information System (GIS). Finally, TCS was separately modelled and mapped. The best regression model was developed using the HH polarization of ALOS-2 PALSAR-2 with an adjusted R2 of 0.78 (p < 0.05). According to the model, the estimated TCS was about 2 Mt for the entire forest, with an average carbon storage of 133 t ha−1. The map showed that the distribution of TCS was heterogenic across the study area. Carbon hotspots were mostly composed of pure stands of Anatolian black pine and mixed, over-mature stands of Lebanese cedar and Taurus fir. It was concluded that the total carbon stocks of forest ecosystems could be estimated using appropriate SAR images at acceptable accuracy levels for forestry purposes. The use of additional ancillary data may provide more delicate and reliable estimations in the future. Given the implications of this study, the spatiotemporal dynamics of carbon can be effectively controlled by forest management when coupled with easily accessible space-borne radar data.

Forest inventory (FI) is the most challenging stage of forest management and planning process. Therefore, in situ surveys are often reinforced by modern remote sensing (RS) methods for collecting forestry-related data more efficiently. This study tests a stateof-the-art data collection method for practical use in the Turkish FI system for the first time. To this end, forest sampling plots were conventionally measured to collect dendrometric data from 437 trees in Artvin and Saçınka Forest Enterprises. Then, each plot was scanned using a handheld mobile laser scanning (HMLS) instrument. Finally, HMLS data were compared against ground measurements via basic FI measures. Based on statistical tests, no apparent differences were found between the two datasets at the plot level (P < 0.05). There were also robust correlations for diameter breast height at individual tree level (r > 0.97; P < 0.01). Residual analysis showed that both positive and negative errors had a homogeneous distribution, except for plot 8 where tree stems were in irregular shapes due to anthropogenic pressures. When all plots' data were aggregated, average values for the number of trees, basal area, and timber volume were estimated as 535 trees/ha-1 , 49.6 m 2 /ha-1 , and 499.7 m 3 /ha-1 , respectively. Furthermore, secondary measures such as the number of saplings and slope were successfully retrieved using HMLS method. The highest overestimation was in timber volume with less than 10% difference at the landscape level. The differences were attributed to poor data quality of conventional measurements, as well as marginal site conditions in some plots. We concluded that the HMLS method met the accuracy standards for most FI measures, except for stand height. Thus, the Turkish FI system could benefit from this novel technology, which in turn supports the implementation of sound forest management and planning.