Department of Agriculture The Forest Resources Forest Service Southern Forest Experiment Station of Puerto Rico New Orleans, Louisiana Resource Bulletin SO-85 October, 1982 Richard A. Birdsey and Peter L. Weaver ACKNOWLEDGEMENTS The assistance of the organizations listed below, and of the individuals in them, is gratefully acknowledged: Department of Natural Resources, Puerto Rico The University of Puerto Rico Southeastern Area State and Private Forestry, U.S. Forest Service Cover: Yourzp secorrdap forest in the t,zcrnl(v of tht Luqurllo Mounralrzs Contents Page HIGHLIGHTS .................................................................... 1 THE FOREST EPJVIRONS1ENT .................................................. 2 Major Forest Influences ......................................................... 2 Geology and Physiography .................................................... 2 Climate ...................................................................... 2 Soils ......................................................................... 3 Population and Land Use ..................................................... 5 Description of the Forests ....................................................... 5 Vegetation Classification and Forest Associations ............................... 5 Forest Plantations ............................................................ 8 Forest Resource Values ................................. ........................ 8 Timber ...................................................................... 8 Mangroves ................................................................... 9 Water and Erosion Control ....................................................10 Rare and Endangered Plant Species ........................................... 11 Wildlife ......................................................................12 Recreation ................................................................... 12 Overview of Research ......................................................... 13 PREVIOUS FOREST SURVEYS AND ESTIMATES ................................ 16 THE 1980 FOREST RESOURCE SURVEY ......................................... 20 Survey Scope and Design ....................................................... 20 Forest Ownership ............................................................... 21 Forest Area .................................................................... 22 Forest Land Increasing .......................................................22 Timberland Increases Follow Retirement of Agricultural Land .................. 22 Most Timberland in Rugged Mountain Areas ...................................23 Species Composition ............................................................ 25 Species Represent Past Human Influence ...................................... 25 Coffee Shade Forests Less Complex Than Secondary Forests ..................... 26 Poor Tree Quality ............................................................27 Timber Volume .................................................................27 Most Volume in Abandoned Coffee Country ....................................27 Low Sawtimber Volume ....................................................... 28 Commercial Prospects for Timberland ............................................ 28 Management Opportunities ..................................................... 29 Implications of this Study .......................................................31 LITERATURE CITED ............................................................ 31 APPENDIX ......................................................................35 Survey Methods ................................................................ 36 Reliability of the Data .......................................................... 36 Definitions of Terms ............................................................37 Standard Tables ................................................................39 Unit Conversion Factors ........................................................ 57 Metric Inventory Standards ..................................................... 57 List of Tree Species Included in Standard Tables .................................. 58 Teak planted along a roadside in the Rio Aba- jo forest. The F'G: st Resources of Puerto Rico Richard A. Birdsey and Peter L. Weaver HIGHLIGHTS In the spring of 1980 a forest in- to past land abuse and unfavorable forest stands. Well-stocked poletim- ventory of Puerto Rico was initiated site characteristics. ber stands offer the best opportun- by the Southern Forest Experiment Much timberland occurs in rug- ity for timber stand improvement, Station. The primary objective of ged mountain regions with poor while nonstocked timberland and this first survey was to assess the soils and high rainfall. Physical fac- poorly stocked sapling-seedling timber production potential of tors, especially steep slopes, can re- stands could be planted with fast young secondary forests. The parti- sult in serious erosion if forest cover growing species. Enrichment plant- tioning of the island into commer- is removed. Deep volcanic soils in ing of secondary forests and better cial and noncommercial survey re- the dissected interior uplands, the management of coffee shade are gions and the concentration of field- favored coffee production area, sup- alternatives for large areas of work in potential commercial port nearly half of the stocked timberland. forests were major features of the timberland. The data gathered in the survey survey. Current species composition of can provide guidelines for an ap- Forest area, timber volume, and timberland reflects prior land use. plied research program on secon- species composition data were Most of the common species tallied dary tropical forest management in obtained by a sampling method in- were once used for coffee shade, Puerto Rico. The survey methods volving a forest-nonforest classi- fruit production, or ornament. Cof- will also contribute to a developing fication on aerial photographs and fee shade forests generally contain body of knowledge on tropical forest on-the-ground measurements of fewer species than abandoned pas- inventory techniques, and should trees at sample locations. The sam- ture or farmland and fewer small be valid for other tropical regions. ple locations were at the intersec- trees. Secondary forests have good tions of a grid of lines spaced 3 kilo- management prospects because of meters apart. In the commercial potential timber species in the survey region, 10,925 photographic smaller diameter classes. The large classifications were made, 437 timber species common in the ma- ground locations were visited, and ture forest are generally absent. 4,506 sample trees were selec- Of the trees tallied, about half ted. Field crews identified 189 tree were classed as growing stock. In species. both coffee shade and other secon- Puerto Rico's forest area has in- dary forests, stands develop with creased dramatically in the last 30 many poor quality, open-grown years, to 279,000 hectares. These trees. young forests result from migration The highest timber volumes per of the rural population away from hectare grow in deep volcanic soils. marginally productive pasture and Sixty percent of the timber volume cropland, &lore than half of the is in 10 species. Because of poor site forest land in Puerto Rico serves im- quality, timber volume is generally portant nontimber needs, including less than 50 cubic meters per hec- watershed protection, wildlife habi- tare. Sawtimber volume, averaging tat, and recreation. About 130,000 4 cubic meters per hectare, is less hectares of forest land were classi- than one-tenth the timber volume. fied as timberland, characterized by Management opportunities are low volumes and stocking levels due not clear-cut because of the diverse Limestone hilts near Arecibo. Richard A. Btrdsey 1s Research Forester, Sout,hern Forest Experiment Statton, Forest Service-USDA, New Orleans, La. Peter L. Lveaver 1s Research Forester, Southern Forest Experimf ?nt Station, Forest Service-CSDA, Inst~tuteof Tropical Forestry, Rio Piedras, Puerto Rtco. THE FC <ST ENVIRONMENT " - Major Forest geosyncline elongated through the cipal hydrologic divide. It is located I[nf luences Antillean region, and active volcan- about 15 kilometers from the south ism occurred until near the end of coast and 40 kilometers from the Puerto Rico is the eastern-most the Middle Eocene epoch, giving north coast because of differential acd smallest of the Greater Antilles rise to predominantly submarine erosion. The Luquillo Mountains and is situated between 18"311and accumulations of volcanic rocks rise to 1074 meters in the northeast- - 17"55' N latitude and 65'37" and (Beinroth 1969).Limestones origin- ern part of the island, and the Cayey 67"17' W longitude. The main is- ated along with tuffaceous shales at Mountains, an extension of the Cor- land, about 160 kilometers long and this time. dillera, rise to 900 meters in the 55 kilometers wide, occupies about Extensive faulting and folding southeastern part. The latter two 8,900 square kilometers including then occurred, accompanied by the are separated by the Caguas Valley. the offshore islands of Vieques, emerging plutonic rocks which are Foothills surround the mountains Culebra and Mona. The small now found in the vicinity of San and merge into coastal lowlands. mountainous island, lying direct- Lorenzo and Utuado. The serpen- Forty-five percent of the land sur- ly in the path