Changes in carbon and nitrogen stocks following conversion of plantation forest to dairy pasture on Vitrands (Pumice Soils), New Zealand

Between 1990 and 2010 some New Zealand plantation forests underwent deforestation to establish dairy farms. The main area of land-use conversion to pasture is to the north of Lake Taupo in the Central North Island (Figures 1 and 2). Pinus radiata (radiata pine) plantations were established in the late 1920s-early 1930s because the Vitrands (Pumice Soils) predominant in the Central North Island were deficient in Co and other trace elements, causing a fatal stock disease in sheep and cattle known as ‘bush sickness’. Bush sickness was subsequently rectified in the mid-1930s with the regular addition of Co, so pastoral farming became viable. The high price of milk solids has recently led to renewed interest in dairying. Recent studies have shown carbon can accumulate following deforestation and establishment of pasture (Fearnside and Barbosa, 1998; Murty et al. 2002; Hedley et al. 2009). However, more information on the rate of accumulation of carbon after deforestation is needed. Increases in soil carbon can improve physical and chemical soil properties, and is an important store of global carbon