echinata Mill.) Forest in the Ozark Highlands, Missouri, USA.

The Eck Memorial Natural Area is the largest old-growth shortleaf pine ( Pinus echinata Mill.) forest in Missouri, USA. The objectives of this study were to characterize vegetation, examine historic and contemporary disturbances, and describe potential vegetation changes for this natural area. Shortleaf pine was the most important tree species at the site and had the highest single species basal area (8.1 m 2 ha -1 ). Old-growth shortleaf pines averaged 230 years in age and ranged from approximately 120 to 325 years. Canopy gaps (< 6 years old) constituted 4% of the total area, and average expanded and actual gap sizes were 421 m2 and 210 m2, respectively. The uneven-aged structure of shortleaf pine suggests that the species has continually regenerated and recruited to the overstory despite the relatively low fire frequency of 44 years. Results of this study suggest that although canopy gaps are important in allowing understory trees to recruit to overstory positions, they are not likely the sole reason for the uneven-aged shortleaf pine structure. During the past century, pine regeneration and recruitment have decreased, possibly as a result of fire suppression. Without major changes in disturbance type and frequency, future forest composition probably will be dominated by hardwoods such as black oak (Quercus velutina Lam.), white oak (Quercus alba L.), and hickories ( Carya Nutt. spp.)— species that were most successful in gap-phase replacement and regeneration. Caracteristicas de los Disturbios y Composicion del Dosel en un Bosque Maduro de Pino de Hoja Corta (Pinus echinata Mill.) en las tierras altas de los Ozark, Missouri, USA. RESUMEN: El area natural Eck Memorial, es el bosque maduro mas grande de pino de hoja corta ( Pinus echinata Mill.) en Missouri, USA. Los objetivos de este estudio fueron caracterizar la vegetacion, examinar los disturbios historicos y contemporaneos, y describir los cambios potenciales de vegetacion para esta area natural. El pino de hoja corta fue el arbol mas importante en el sitio y tuvo el area basal mayor por especie (8.1 m2 ha-1). Los pinos de hoja corta maduros promediaron 230 anos de edad y variaron de 120 a 325 anos. Los gaps del dosel ( < 6 anos de antiguedad) constituyeron el 4% del area total, y promediaron una superficie, expandida y actual, de 421 m 2 y 210 m 2 respectivamente. La despareja estructura de edades de los pinos de hoja corta, sugieren que la especie se ha regenerado continuamente y se ha reclutado al dosel, aun con una baja frecuencia de fuego de 44 anos. Los resultados de este estudio sugieren que aunque los gaps del dosel son importantes al permitir la incorporacion de arboles al dosel, ellos no son posiblemente la unica razon para la estructura despareja de edades de los pinos de hoja corta. Durante el ultimo siglo, la regeneracion y el reclutamiento de pinos ha disminuido, posiblemente como resultado de la supresion de fuegos. Sin cambios mayores en la frecuencia y tipo de disturbio, la composicion futura del bosque probablemente este dominada por maderas duras, tales como Quercus velutina Lam., Quercus alba L., y Carya Nutt. spp.—especies que fueron mas exitosas en el remplazo y la regeneracion de los gaps.

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