Lugo, A. E., F. Scatena, and C. F. Jordan. 1999. NPP Tropical Forest: Luquillo, Puerto Rico, 1963-1994. Data set. Available on-line [http://www.daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.
The Luquillo Experimental Forest is situated in the Luquillo Mountains of eastern Puerto Rico (18.32 N 65.82 W), about 35 km east-southeast of San Juan, and operates under the auspices of the International Institute of Tropical Forestry, Rio Pedras, Puerto Rico. Its total area is about 11,000 ha, of which the various research areas comprise 3,000 ha. Different forest types are found associated with a variety of soil types and elevations (100-1000 m), and rainfall ranges from 2330 mm at 100 m to 4700 mm at 700 m elevation. Most of the upper elevation slopes of the Luquillo Experimental Forest are old-growth dwarf cloud forest, colorado forest, and palm forest that has been under some form of protection since Europeans landed in Puerto Rico in 1494. The lower elevations of the reserve, which was established in 1903, are comprised of old or cut-over colorado and tabonuco-type forests. Most of the Luquillo Experimental Forest has never been clear-cut and has remained forested. However, selective logging, subsistence agriculture, and shade coffee-growing took place during and before World War II (1939-1945).
Intense rainfall that triggers landslides and causes localized disturbance to soil and vegetation occurs nearly every year. Every 5 to 10 years a hurricane passes close enough to the island of Puerto Rico to cause more severe heavy rains and localized damage to vegetation. Approximately once every 21 years, a hurricane crosses over some part of the island, and once every 50 to 60 years a hurricane crosses directly over the Luquillo Experimental Forest. The largest hurricanes to damage the Luquillo Experimental Forest research areas this century occurred in 1932 and 1989. Hurricanes in 1928, 1956, and 1998 also resulted in localized damage.
Field studies commenced under the the Rain Forest Project of the U.S. Atomic Energy Commission (1963-1968) and have continued since the early 1980s under the Luquillo Long-Term Ecological Research (LTER) program. The most recent studies include the effects of Hurricane Hugo, which caused extensive damage to the forest in September 1989.
The last anthropogenic (or land-use) disturbance that occurred in the two major study sites in the tabonuco type forest (El Verde and Bisley) occurred in the in the early 1930s. These areas have been the focus of much of the long-term studies in natural stands of mature secondary forest. Shorter duration studies have also been carried out in younger secondary forest (11-30 years old) at Guzman, Cubuy, and Sabana. Further studies have examined several types of tropical forest along a catena rising to 1000 m elevation.
Many estimates of above-ground NPP of natural forest at Luquillo (915-1100 g/m2/year) agree with the figure of 1033 g/m2/year from the earliest studies at El Verde, although ANPP decreases for the forest at higher elevations. However, the floodplain palm forest was found to have a significantly higher ANPP (1950 g/m2/year), and above-ground net primary productivity (ANPP) at the Bisley site exceeded even this figure (2160 g/m2/year) in the aftermath of Hurricane Hugo, possibly due to the flush of nutrients. Below-ground NPP has been measured at only one site (Guzman), where total NPP was estimated at 1945 g/m2/year.
Additional climate data sets from several stations are available from the Luquillo LTER Web site.
Tel. +1 (787) 766-5335/ 740-1032
Fax +1 (787) 766-6302/ 6303
E-mail: alugo@LTERnet.edu / f_scatena@upr1.upr.clu.edu
Alternative Contact: Eda C. Melendez
Data Manager, Luquillo LTER
University of Puerto Rico
P.O. Box 363682
PUERTO RICO 00936
Telephone: +1 (787) 767-0350/0338
Fax: +1 (787) 758-0815
E-mail: emelend@sunites.upr.clu.edu
Alternative Contact: Dr. C. F. Jordan
Institute of Ecology
University of Georgia
Athens, Georgia 30602
U.S.A.
Telephone: +1 (706) 542-2968
Fax: +1 (706) 542-6040
E-mail: cfjordan@uga.cc.uga.edu
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