The CLAMP calibration datasets consist of matching pairs spreadsheets. Each pair comprises a file containing physiognomic data from modern vegetation sites and a file with the corresponding meteorological (climate) data for that same suite of sites.

As CLAMP has developed the number of sites used in the calibrations has increased and changed as the structure of global leaf form/climate relationships have become better understood. The global suite of CLAMP sites now spans all continents except Antarctica and altidudes ranging from sea level to over 3600m.

The earliest calibration suites still in use are Physg3brAZ and Physg3arAZ. These comprise 144 and 173 sites respectively, primarily from North America, Japan, the Caribbean and Pacifica. The difference between the two calibrations is that 3br lacks the so-called 'Alpine Nest', which are sites that experience significant cold due to high latitide or altitude or both. Because they both incorporate sites from southwestern USA and Mexico they represent the weak North American summer monsoon, as well as some sites in Japan that experience the margin of the East Asia monsoon area, but most sites represent non-monsoonal climates. These calibrations are useful for northern hemisphere locations that are suspected of being non-monsoonal.

Asia2 is a calibration suite of 177 sites that incorporates those contributing to 3br but also includes many others from China, Thailand and India. As such it represents strongly monsoonal climates and has proved reliable (in that is yields predictions matched by isotopic proxies) for tracking monsoon development and elevation changes in Asia. Asia2 uses only gridded climate data

The southern hemisphere (SH) calibration comprises 90 sites inluding from Australia, New Zealand, South Africa, Chile and Aregentina. Because the southern hemisphere has a higher proportion of evergreen taxa due to the relatively low latitudinal location of non-Antarctic land masses, and some areas like New Zealand have been to some extent genetically isolated for most of angiosperm evolution, southern hemisphere vegetation has a somewhat different relationship to climate than that seen in the northern hemisphere.

In total the CLAMP global dataset currently comprises physiognomic and climate data from 424 locations. The coverage is not uniform and, apart from the obvious exception of Antarctica (no woody dicots - yet), the only major vegetation type not represented is equatorial forests. The published global dataset available on this site for general analytical purposes comprises 378 sites.

Because linear vectors cannot properly represent the complex structure of global leaf trait/climate relationships the statistical uncertainties associated with such a wide ranging data suite are larger than for other region-specific calibrations. For this reason the global are only be used to explore where an unknown (fossil) site plots within the global physiognomic space in order to make an informed decision as to which of the regional calibrations is the most appropriate.

	A CLAMP sampled forest in Kerala, southern India.