This data set provides measurements of soil carbon dioxide (CO2) emission rates, soil moisture, relative humidity (RH), temperature, and litterfall from six types of tree plantations at the La Selva Biological Station, Costa Rica. Soil CO2 flux and related measurements were made 1) hourly during 2-day diel field campaigns and 2) as single daytime measurements during multiple survey campaigns, over the period 2004-2010. All measurements were made at the same sites to compare hourly, monthly, and inter-annual variations. Most of the emissions data represent a single soil CO2 flux measurement, with three to five measurements per plot. Litterfall was collected monthly from 2003-2009 and was sorted into fractions prior to drying.