Showing papers by "Oliver L. Phillips published in 1994"

Increasing turnover through time in tropical forests.

Abstract: Tree turnover rates were assessed at 40 tropical forest sites. Averaged across inventoried forests, turnover, as measured by tree mortality and recruitment, has increased since the 1950s, with an apparent pantropical acceleration since 1980. Among 22 mature forest sites with two or more inventory periods, forest turnover also increased. The trend in forest dynamics may have profound effects on biological diversity.

Quantitative Ethnobotany and Amazonian Conservation

Abstract: We use quantitative ethnobotanical data to compare the usefulness of six floristically distinct forest types to mestizo people at Tambopata, southeast Peru. We aim to evaluate which forest types are most useful, and why. Ethnobotanical data were collected with informants in inventory plots and analyzed using a new technique that uses a two-tier calculation process to derive an “informant indexed” estimate of each species’ use value. Use values are estimated based on the degree of consistency between repeated interviews of each informant and between different informants. We show that (1) in 6.1 ha, 94% of woody stems are “useful” to mestizos. (2) Based on percentages of useful plants per plot, there is little difference between each forest type. (3) Simply calculating the percent of useful plants is misleading, however, because most species have minor uses, and only a few are exceptionally useful. (4) Using the informant indexing technique, we demonstrate significant differences between each forest type’s utility. Mature forests of present and former floodplains are more useful than other forest types, mostly due to their importance as sources of construction materials and food. (5) Lower floodplain is more useful medicinally, swamp more important commercially, and terra firme sandy more important technologically; they are not easily substituted for some of these uses. (6) On average, 80% of the value of forest plant products to mestizos is subsistence value; only 20% is commercial. We conclude that (1) to maintain cultural autonomy, Amazonian people may need access to all local forest types, and (2) present and former floodplain forests in western Amazonia should be a conservation priority. We make these broad conclusions on the basis of evidence of: (1) ethnoecological similarities among mestizo cultures in Peruvian Amazonia; (2) the similarity of family-level floristic composition at Tambopata and elsewhere in western Amazonia, (3) rapid floodplain deforestation; and (4) floodplain resource overextraction. Conservationists should focus on helping communities gain control of floodplain resources. Se empleo datos etnobotanicos cuantitativos para comparar la utilidad de seis tipos de bosques floristicamente distintos, con plantas usadas por la poblacion mestiza en Tambopata, sureste de Peru. Datos etnobotanicos fueron registrados de informantes en parcelas inventariadas, usando una nueva tecnica que considera un procedimiento simple para obtener un estimado del valor de uso de cada especie. Los valores de uso se basan en el grado de consistencia de entrevistas reiteradas con uno y varios informantes (Phillips & Gentry, 1993a). L’os resultados muestran que (1) en 6.1 ha, 94% de individuos arboreos son “utiles” a la poblacion. (2) Basados en el porcentaje de plantas utiles por plot, hay muy escasa diferencia entre tipos de bosque. (3) El porcentaje de plantas utiles incluye sin embargo una mayoria de especies a las que se les da usos menores, y son muy pocas las especies que brindan mayor utilidad, por lo tanto los calculos de porcentaje de plantas utiles son erronios. (4) Empleando la tecnica del indice de utilidad, se encontraron diferencias significativas entre la utilidad de diferentes tipos de bosque. Las areas de bosque maduro en zonas con suelos y terrazas aluviales proveen mas plantar muy utiles que otros tipos de bosque, debido mayormente a su importancia como fuentes de material de construccion y alimentos. (5) Las areas aluviales mas bajas tienen mayor valor como proveedoras de plantas medicinales, las areas pantanosas son utiles para productos comerciales y las de “terra firme” con mayor posibilidad de uso tecnologico; algunos de estos usos no son facilmente sustituibles. (6) En promedio, un 80% del valor de los productos del bosque son valor de subsistenceia, solo 20% del valor del bosque es valor comercial. Se obtienen las siguientes conclusiones (1) para mantener autonomia cultural, la poblacion amazonica necesita tener acceso a todos los tipos de bosques locales, y (2) las zonas de bosques aluviales, actuales y pasadas, de la region amazonica, deben priorizarse para la conservacion. Arribamos a estas conclusiones amplias basados en; (1) la similitud de la etnoecologica de la poblacion mestiza de la Amazonia Peruana; (2) la similitud floristica al nivel de familia, del area de estudio con el resto de la Amazonia peruana; (3) el rapido proceso de deforestacion en las zonas de bosque aluvial; y (4) sobroexplotacion de los recursos de las areas aluviales. Por tanto, la recomendacion a los conservacionistas es ayudar a las comunidades a adquirir el control de los recursos en estas zonas.

Dynamics and species richness of tropical rain forests.

Abstract: We present a worldwide analysis of humid tropical forest dynamics and tree species richness. New tree mortality, recruitment, and species richness data include the most dynamic and diverse mature tropical forests known. Twenty-five sites show a strong tendency for the most species-rich forests to be dynamic and aseasonal. Mean annual tree mortality and recruitment-turnover-is the most predictive factor of species richness, implying that small-scale disturbance helps regulate tropical forest diversity. Turnover rates are also closely related to the amount of basal area turnover in mature tropical forests. Therefore the contribution of small-scale disturbance to maintaining tropical forest diversity may ultimately be driven by ecosystem productivity.