RAINFOR GEM Intensive Plots Manual (pdf) - University of Oxford

After leaving the rhizotrons for two months to recover from the disturbance of installation (Girardin et al. 2010,but cf. Metcalfe et al. 2008a who allowed nine months), rhizotron root length should be recorded monthly ateach rhizotron either using protocol #1 or #2 (see below). Soil moisture and temperature should be recordedevery session at the same point within 0.5 m of the rhizotron (but not near the rhizotron screen). If possibleallow only one person to trace the roots, to avoid apparent changes in root dynamics due to changes betweenpersonnel. Transparencies of root tracings from the rhizotrons should be scanned (colour scan, jpg file format,150 dpi) and saved in a file.< 1 mm1-2 mm2-3 mm>3 mm< 1 mm1-2 mm2-3 mm>3 mmThere are two different colour conventions for the root size classess 50 black-red-blue-green as used in South America (left stack andthe photo: left to right Cécile Girardin, Liliana Durand, Walter Huaraca Huasco and Marlene Mamani Solórzano in Trocha Union plot4, Peru) or black-blue-red-green as specified in Metcalfe et al. (2009) and used in Malaysia (right stack). Because of this, it isessential to note which convention is being followed with any rhizotron transparencies.49 Cécile Girardin recommends Sharpie coloured permanent markers as the best for drawing in wet conditions.50 Metcalfe et al. (2009:§4.1.2.2.3) specified “3 mm = green” (correcting the typothat put “4 mm” for the last category). For mysterious reasons the blue and red colours were swapped at some point in South America.The current situation (2012) is that, because most intensive plots are in South America, the majority of rhizotron users across thenetwork are using their colours as in the photo, but as long as good records are kept there is no problem using either colourconvention.40