Impacts of conversion from forestry to pasture on soil physical properties of Vitrands (Pumice Soils) in central North Island, New Zealand

Tens of thousands of hectares of land have been converted from plantation forest to pasture in the central North Island of New Zealand between 2000 and 2010. The land use change was driven by the perceived better long term returns from dairy farming compared with forestry. Pumice Soils (NZ Soil Classification, equivalent to Vitrands in Soil Taxonomy) in the central North Island are formed on pumice deposited mainly from the AD 232 ± 5 Taupo volcanic eruption. The texture of Pumice Soils (Figure 1) varies from silt to coarse gravel and they have weak structure and erode easily when disturbed. Water holding capacity may be low but increases as the organic matter content of the topsoil is built up