No: 69, 2008 1 Geliþ: 20.11.2007 / Kabul: 03.01.2008 INTRODUCTION Soil respiration is affected in a complex way by temperature, moisture, soil properties, quality and quantity of decomposing organic substrates (Kirschbaum 1995, Raich and Tüfekçioðlu 2000), and predictions of future changes rely on detailed knowledge on the effects of each of these factors but also on their interaction (Uvarov et al. 2006). Temperature, together with moisture content, is the most important environmental factor affecting microbial growth and activity in soils (Dalias et al. 2001b, Pietikäinen et al. 2005, Uvarov et al. 2006). The importance of the temperature dependence of soil organisms has been further emphasized during recent years due to the global warming issue (Kirschbaum 1995, Kirschbaum 2000, Reichstein et al. 2000), since microorganisms are the main group producing CO 2 during decomposition of organic material in soil (Pietikäinen et al. 2005). Acacia (Acacia cyanophylla Lindley, Fabaceae) is described as a garden and park plant (Seçmen et al. 1995) with a large adaptability to the Mediterranean Emel ZENGÝN, Hüsniye AKA SAÐLIKER*, Cengiz DARICI University of Çukurova, Faculty of Science and Arts, Department of Biology, 01330 Balcalý, Adana-TURKEY *Corresponding author: crocus@cu.edu.tr Carbon Mineralization of Acacia cyanophylla Soils under the Different Temperature and Humidity Conditions Abstract The aim of this study was to determine how carbon (C) mineralization of acacia (Acacia cyanophylla, Fabaceae) soil are affected by the different temperature (23°C and 28°C) and humidity (80% and 60% of their field capacity) conditions in the laboratory. The acacia soils were collected from Çukurova University campus in the eastern Mediterranean region of Turkey. C mineralization of all soils was determined using CO 2 respiration method. The microbial activity increased together with temperature increases. The micro- bial activity in the soils humidified to 80% of field capacity was significantly different from field capacity and 60% of field capacity at both 23°C and 28°C temperatures (p<0.001). The ratios (%) of C mineraliza- tion of 80% of field capacity at 23°C and 28°C were also significantly higher than all of the others (p<0.001). These findings might suggest that 80% of field capacity of acacia soil is better humidity for microbial activity at both 23°C and 28°C temperatures into 30 days. Keywords: Acacia cyanophylla, carbon mineralization, humidity, microbial activity, temperature. Farklý Sýcaklýk ve Nem Koþullarý Altýnda Acacia cyanophylla Topraklarýnýn Karbon Mineralizasyonu Özet Bu çalýþmanýn amacý laboratuvarda farklý sýcaklýk (23°C ve 28°C) ve nem (tarla kapasitesinin %60 ve %80'i) koþullarýnýn akasya (Acacia cyanophylla, Fabaceae) topraklarýnýn karbon (C) mineralizasyonunu nasýl et- kilediðini belirlemektir. Akasya topraklarý Türkiye'nin Doðu Akdeniz Bölgesindeki Çukurova Üniversitesi kampusünden toplanmýþtýr. Tüm topraklarýn C mineralizasyonu CO 2 respirasyon yöntemi kullanýlarak belirlenmiþtir. Mikrobiyal aktivite sýcaklýk artýþý ile birlikte artmýþtýr. Tarla kapasitesinin %80'ine nem- lendirilmiþ topraklarda mikrobiyal aktivite hem 23°C hem de 28°C sýcaklýklarda tarla kapasitesi ve tarla kap- asitesinin %60'ýndan anlamlý düzeyde farklýdýr (p<0.001). 23°C ve 28°C'de tarla kapasitesinin %80'inin C mineralizasyon oranlarý (%) da diðerlerinin tümünden anlamlý düzeyde yüksektir (p<0.001). Bu bulgular akasya topraklarýnýn tarla kapasitesinin %80'inin 30 gün içinde hem 23°C hem de 28°C sýcaklýklarda mikro- biyal aktivite için en iyi nem olduðunu öne sürebilir. Anahtar Kelimeler: Acacia cyanophylla, karbon mineralizasyonu, mikrobiyal aktivite, nem, sýcaklýk. Zengin E, Saðlýker HA, Darýcý C (2008) Carbon Mineralization of Acacia cyanophylla Soils under the Different Temperature and Humidity Conditions. Ekoloji 18, 69, 1-6. Ekoloji 18, 69, 1-6 (2008)