Topoclimate South: Integrated climate and soil mapping in Southland
Local scale climate mapping is an essential tool for risk assessment in sustainable land use. The Southland Region, located in the south of New Zealand, has average temperatures that are marginal for the growth of many crops. Detailed climate information is therefore especially relevant in this area. This paper describes a major community initiative underway in Southland involving mapping of climate and soils at the local scale. The Topoclimate South Project has set out to gather this information, and is extending previous studies by applying new technologies to make a regional scale survey possible. A network of 900 "Tinytag" air temperature loggers has been established in the first year of this three year project, with a total of 800,000 ha to be mapped over the three year period. Dataloggers in screens are suspended at a height of 1.2 metres in a wire mesh cage for protection from stock. They are set to record air temperature at six minute intervals for the whole year, with data being downloaded every four months. Air and soil temperature recording sites were selected to represent the major topographic and climatic elements of the landscape. Sites were spatially distributed to represent an average thermal area of 170 ha. Soils information is being mapped concurrently and to the same scale. Linear regression analysis will compare each of the recording sites with the nearest long-term weather station records (with at least 30 years of temperature records). This will allow the generation of estimates of long-term means for each site. Maximum, minimum, and average daily temperatures will be extracted for each site, and average growing degree days (GDDs) calculated for the warm season and total year. A spatial interpolation technique will be employed to derive estimates of GDDs over the landscape, and in this way local scale climates will be plotted onto a topographic map of the area. Easy access to information resulting from this study is needed by the end user. Every farmer who agrees to grant access to their property will receive a free soil and GDD map of their area, and this information will also be available through an Internet web site (www.topoclimate-south.co.nz) and bureau service.