Ulas Yunus Ozkan

Assessment of visual landscape quality using IKONOS imagery

The assessment of visual landscape quality is of importance to the management of urban woodlands. Satellite remote sensing may be used for this purpose as a substitute for traditional survey techniques that are both labour-intensive and time-consuming. This study examines the association between the quality of the perceived visual landscape in urban woodlands and texture measures extracted from IKONOS satellite data, which features 4-m spatial resolution and four spectral bands. The study was conducted in the woodlands of Istanbul (the most important element of urban mosaic) lying along both shores of the Bosporus Strait. The visual quality assessment applied in this study is based on the perceptual approach and was performed via a survey of expressed preferences. For this purpose, representative photographs of real scenery were used to elicit observers’ preferences. A slide show comprising 33 images was presented to a group of 153 volunteers (all undergraduate students), and they were asked to rate the visual quality of each on a 10-point scale (1 for very low visual quality, 10 for very high). Average visual quality scores were calculated for landscape. Texture measures were acquired using the two methods: pixel-based and object-based. Pixel-based texture measures were extracted from the first principle component (PC1) image. Object-based texture measures were extracted by using the original four bands. The association between image texture measures and perceived visual landscape quality was tested via Pearson’s correlation coefficient. The analysis found a strong linear association between image texture measures and visual quality. The highest correlation coefficient was calculated between standard deviation of gray levels (SDGL) (one of the pixel-based texture measures) and visual quality (r = 0.82, P < 0.05). The results showed that perceived visual quality of urban woodland landscapes can be estimated by using texture measures extracted from satellite data in combination with appropriate modelling techniques.

Modelling Bird Species Richness Using Satellite Data

Simple and easily measured attributes as a surrogate for biodiversity are needed for a successful biodiversity management in forest ecosystems.

Structural characteristics of planted and naturally regenerated brutian pine stands

Akdeniz bolgesinde, dogal genclestirme ve agaclandirma yoluyla kurulan genc kizilcam mescerelerin yuzolcumu giderek artmaktadir. Kizilcam orman ekosistemlerinde, etkili bir karbon ve biyolojik cesitlilik yonetimi icin, yeni kurulan bu mescerelerin yapisal ozellikleri, yasli dogal mescereler goz onunde bulundurularak degerlendirilmedir. Bu calismada; i) dogal genclestirme ve agaclandirma yoluyla kurulmus olan benzer yaslardaki mescerelerin yapisal ozelliklerinin karsilastirilmasi, ii) mescere yapisal ozelliklerinin suksesyon evrelerine gore egiliminin belirlenmesi ve bu egilimin dogal mescere ozelliklerine benzerliginin ortaya koyulmasi amaclanmistir. Yukselti, baki, arazi egimi ve anakaya bakimindan benzer olan 8 farkli mescere grubu tespit edilmistir. Her mescere grubundan 5 ornek mescere secilmistir. Bu mescereler icinde rasgele konumlandirilan 5 ornek alanda, mescere ozellikleri ile ilgili olcum ve gozlemler yapilmistir. Mescere yapisal ozellikleri olarak; gogus yuzeyi (m2/ha), mescere hacmi (m3/ha), kapalilik derecesi (%), dokuntu miktari (ton/ha), humus (ton/ha), ust topraktaki karbon (C) orani (%), kalin olu odun miktari (m3/ha), ince olu odun miktari (ton/ha) ve odunsu tur zenginligi kullanilmistir. Calismada genclestirme ve agaclandirma faaliyetlerinin, kizilcam orman ekosistemlerine hem olumlu hem de olumsuz etkilerinin oldugu tespit edilmistir. Her ne kadar genc mescerelerin yapisal ozelliklerindeki yasa bagli trend, yasli mescerelerle olan farki kapatabilecek gibi gorulse de, dokuntu ve humus miktari ve ust topraktaki C orani gibi ozelliklerin normale donmesi icin daha uzun sureye ihtiyac bulunmaktadir. Agaclandirma calismalari, odun uretimi ve orman ekosistemlerinde tutulan karbon miktarinin arttirilmasina onemli katkilar yapmaktadir. Fakat bu faaliyetler, yaban hayvanlari icin onemli habitatlari barindiran calilik alanlarin azalmasina yol acmaktadir. Sonuc olarak, yogun odun isletmeciligi yapilan kizilcam ormanlarinda, yeterli miktarda dogal yasli mescere ve makilik alanlar dokunulmadan birakilmalidir. Anahtar kelimeler: Karbon, Biyolojik cesitlilik, Dokuntu, Humus, Olu odun