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Estate Thomas Experimental Forest - U.S. Virgin Islands

The Estate Thomas Experimental Forest was established in 1964, encompasses 60 ha, and is the easternmost experimental forest. It is located at an elevation of 76 to 137 m above sea level 6.4 km west of Christiansted, Saint Croix, U.S. Virgin Islands. The St. Croix Sugar Factory, Inc., owned Estate Thomas in 1917 when the U.S. government purchased St. Croix from Denmark. The West Indies Sugar Factory bought the land in 1928 and sold it in 1931 to the Chabert Family. The U.S. government bought it in 1934 and the Forest Service acquired the tract from the Virgin Islands Corporation in 1963. Chief Ed Cliff designated the Estate Thomas Experimental Forest on March 11, 1964. The International Institute of Tropical Forestry administers the Estate Thomas in collaboration with the U.S. Virgin Islands Government. The vegetation is representative of the dry forests of the Virgin Islands, and by its location near the geographic center of St. Croix, it is a strategic area of open space in a densely populated island.


The forest is classified as a subtropical dry forest in the Holdridge Life Zone Classification System. Annual rainfall averages 1,100 mm and annual temperature averages 26.7 °C with a daily range of 8 °C. There is no frost. Hurricanes and storms pass the vicinity of the forest at relatively high frequencies, i.e., about 50 per century.


The hilly slopes have shallow and very stony clay soils. In general, soils are well drained, gravelly loam, with little to moderate slope and formed from parent calcareous marine sediments.


There is no original vegetation on the Estate Thomas, though forests cover most of the property. Hills comprise 76% of the property and were farmed until 1928; valleys were farmed until 1953. Sugar cane was the predominant crop. The vegetation now includes secondary forests that emerged naturally after abandonment of agriculture, and tree plantations established by the Forest Service for experimental purposes. West Indian or smallleaf mahogany, a naturalized species, dominates the secondary forests located in the hilly sector of the forest. The Forest Service used the flat areas for experimental plantations, including teak, toona, Spanish cedar, lignum-vitae, and small-leaf mahogany.
An inventory of the natural vegetation in the Estate Thomas identified 110 plant species, including 83 woody species in 1.73 ha. Basal area and tree density were 17.6 m²/ha and 1,672 stems/ha, respectively, and the average canopy height was 7.7 m. It was also documented that non-native species dominated the tree and shrub layers of the forest.

Long-term Databases

Most of the data collected on the Estate Thomas EF are from tree plantations of different species and provenances. Studies included 15 exotic tree species between 1961 and 1966. The tree diameter data are available through the International Institute of Tropical Forestry.

Research, Past and Present

Research began on the Estate Thomas in 1930 with the planting of small-leaf mahogany and other timber species. The overall objective was understanding the adaptability of tropical timber species to conditions on St. Croix. The Forest Service used the results from research at the forest to improve tree productivity on nearby private lands. Today, research focuses on the restoration of tropical dry forests following deforestation. The recent vegetation inventory provides the base information needed for future decisions on restoration research and forest management activities at this site.

Major Research Accomplishments and Effects on Management

Research on the Estate Thomas produced the information required to reforest dry lands in the tropics of the U.S. Virgin Islands. The management of West Indian mahogany in these islands is a product of research at the experimental forest. Research there also established the expected tree growth rates for the region and identified the timber species with the best adaptability to conditions in the U.S. Virgin Islands.

Research Opportunities

The Estate Thomas is available for studying secondary forest succession on abandoned agricultural lands in dry life zones. Such deforested dry forest land predominates in the tropics because of the high population densities in dry areas and the high rates of deforestation. Most of the original tree plantations did not survive various hurricanes that passed over the site, and these sites are now undergoing active succession of native and non-native species. Numerous long-term plantation and natural secondary vegetation plots are available for research. The forest is also available for elementary and secondary education.


The main collaborators of the research program are the U.S. Virgin Islands Government Department of Agriculture, the University of the Virgin Islands Agriculture Experiment Station, and St. Croix Environmental Association.


Estate Thomas has an open pavilion with a compost bathroom; these are available to support research activities and conservation education efforts.
Latitude: 17° 44' 22.63" N (17.739619 decimal degrees)
Longitude: 64° 44' 16.46" W (-64.737906 decimal degrees)

Contact Information

International Institute of Tropical Forestry
PO Box 25000
Río Piedras PR 00928-5000
Tel: (787) 766-5335