http://vocab.lternet.edu/vocab/vocab/http://vocab.lternet.edu/vocab/vocab/skos/883net ecosystem exchange http://vocab.lternet.edu/vocab/vocab/skos/883 ecosystem properties BT http://vocab.lternet.edu/vocab/vocab/skos/883 eddy covariance RT http://vocab.lternet.edu/vocab/vocab/skos/883 NEE UF