IntroductionCarbon (C) is one of the principal elemental components of ecosystems and intimately coupled with biogeochemical cycles of other major elements such as nitrogen, phosphorus, sulfur, oxygen, and hydrogen.1Primary productivity, herbivory, litterfall, plant and soil respiration, and natural and human disturbances are the primary ecosystem processes that control the global C cycle.2Soils contain approximately twice as much C (1580 Pg) as the atmosphere (750 Pg) or terrestrial vegetation (610 Pg).3Globally, the amounts of C entering soil by litterfall and leaving soil by respiration are 61.4 Pg C and 60 Pg C annually, respectively.3Primary productivity of forests cycles approximately one-twelfth of the atmospheric stock of C annually. Globally, forests and woodlands cover about 3.4 Gha (22.9%) and 1.7 Gha (11.5%) of the total land surface, respectively.4Forests account for approximately 50% (1146 Pg C) of the total terrestrial C pool, with two-thirds (787 Pg C) of this residing in forest soils and the rest (359 Pg C) in vegetation.5Local human activities modifying C pools and fluxes have the potential to alter the global C cycle and climate. The injection of 480 Pg C into the atmosphere through fossil-fuel combustion and land-use and land-cover (LULC) changes since the Industrial Revolution has disturbed the natural global cycling of C among vegetation, soil, atmosphere, and oceans.6Deforestation is one of the major LULC changes that released 2.24 Pg C per year to the atmosphere in the 1990s.7Quantification of C stocks and fluxes of forest ecosystems is of considerable interest in the context of mitigation of global climate change for the following reasons: (1) forest ecosystems store larger quantities of atmospheric CO2for a longer period of time in vegetation and soil than the other terrestrial ecosystems, (2) countries seek to comply with agreements under the UN Framework Convention on Climate Change; and (3) scientists seek to account for the imbalance in the global C budget (termed as missing sink comprising up to 1.8 Pg C per year in the 1980s).8National budgets of forest C sequestration may be a practical way of monitoring reductions and increases in atmospheric CO2concentration and at the same time may contribute to sustainable biological productivity of ecosystems. However, forest C sequestration should be regarded as a component of a mitigation strategy, not as a substitute for the changes required in energy supply, use and technology if atmospheric CO2concentration is to be stabilized.Turkey (36–42°N, 26–45°E) has a land area of 779 452 km2with 20 million ha located in arid and 31 million ha located in semi-arid climatic regions. Turkey is a predominantly mountainous country, and true lowland is confined to the coastal fringes, with an average altitude of 1250 m and the highest point of 5137 m (Mount Ararat) above sea level near the Iranian border. Gently rolling, fertile plains cover Thrace and extend along the Black Sea coast of Anatolia. Along the coast of the Aegean Sea are broad, fertile river valleys. A narrow strip of fertile land lies along the Mediterranean Sea. The prevailing climate varies among the Aegean, Mediterranean, Central, East and Southeast regions of Turkey. There are two main climate belts: (1) ‘Temperate’ characterized by cold winters and warm summers with a year-round precipitation, and (2) ‘Mediterranean’ characterized by mild winters and hot and dry summers with more than 65% of the mean annual precipitation occuring in the winter. The temperature reaches a maximum of 45 °C in the south and southeast during the summer and a minimum of −40 °C in the east and central Anatolia during the winter, with a mean annual temperature of 19 °C. Annual precipitation ranges from 250 mm in the central and southeastern regions to 2500 mm in the northeastern coastal plains and mountain regions, with a mean annual precipitation of 650 mm.Rapid population growth, increased human consumption, conversion of forests to agricultural and urban-industrial lands, overgrazing, overharvesting, prevailing semi-arid conditions, poverty, economic crises, rapid urbanization-industrialization, and migration of rural populations to urban areas have had significant adverse impacts on conservation and sustainable management of forest resources, thus causing an increase in degradation and destruction of forest ecosystem productivity. Many forests are exploited by the rural population as a source of fuelwood and charcoal for their domestic needs. The percentage of total roundwood production consumed for fuel was 44% in Turkey.4About 2000 fires have occurred in Turkey in the last ten years, burning about 12 500 ha annually.9The land area of forests degraded due to overexploitation and urban-industrial expansions was estimated at 11.7 Mha.10Conversion of forest, pasture, and wetlands into agricultural lands between 1948 and 1994 has amounted to 21.5 Mha.10,11Regenerating and C sequestration capacities of forest in Turkey are restricted by soil erosion and shallow soils in that 75% of the total land area is prone to different levels of erosion, and only 14% of the total land area has a soil depth of 90 cm or more.10Sharpet al.(1975) calculated forest biomass of North Carolina in the USA, based on forest inventory data and a constant biomass expansion factor (BEF) of 2.0 t m−3.12Brown and Lugo (1984) used two different BEF values of 1.6 for closed tropical forests and 3.0 for open tropical forests.13Kauppiet al.(1992) quantified a C budget of European forests by applying a BEF range of 0.6 to 0.8.14Turneret al.(1995) estimated C budget for forests in the USA by using a constant ratio of whole-tree C to merchantable-bole C across age classes within a forest type.15In the work presented here, carbon budget for forest and woodland ecosystems in Turkey was calculated separately for coniferous and deciduous tree groups, based on UN-ECE/FAO national forest inventory data in 1996.16