Bernard R. Parresol

Additivity in tree biomass components of Pyrenean oak (Quercus pyrenaica Willd.)

In tree biomass estimations, it is important to consider the property of additivity, i.e., the total tree biomass should equal the sum of the components. This work presents functions that allow estimation of the stem and crown dry weight components of Pyrenean oak (Quercus pyrenaica Willd.) trees. A procedure that considers additivity of tree biomass components is presented, and applied to a particular case. The application of a simultaneous equations system estimation procedure that used parameter restrictions and considered residual contemporaneous correlations allowed more efficient estimates and consistent prediction intervals.

Dendroecological Analysis of Cordia Alliodora, Pseudobombax Septenatum and Annona Spraguei in Central Panama

Several plant communities in central Panama, each community located near a weather station, contain trees with annual growth rings, i. e. Cordia alliodora, Pseudobombax septenatum, and Annona spraguei. Tree-ring data are particularly valuable when concomitant weather information is readily available. Patterns of growth for the above species of trees were investigated across central Panama in relation to climate. A linear aggregate climate model was fitted to chronologies of each species at three sites along a rainfall gradient. Comparisons were made among sites to help explain how climate influences tree growth within central Panama.

A density-integral approach to estimating stem biomass

Abstract An alternative to ratio models for predicting bole dry weight of wood, given diameter at breast height, total tree height and limits of utilization, is presented. A generalized density-integral model is developed on the basis of some simple calculus of mass theory. To demonstrate the application and efficacy of this new integral approach, specific equations are developed for slash pine in the West Gulf Coast of the United States. These integrated equations, when compared with weight-ratio equations, gave more precise estimates of sectional bole weight.

Basal area growth for 15 tropical tree species in Puerto Rico

Abstract The tabonuco forests of Puerto Rico support a diverse population of tree species valued for timber, fuel, food, wildlife food and cover, and erosion control among other uses. Tree basal area growth data spanning 39 years are available on 15 species from eight permanent plots in the Luquillo Experimental Forest. The complexity of the rain forest challenges current forest stand modeling techniques. As a starting point individual tree basal area growth is modeled using the Chapman-Richards function constrained for hypothetical maximum tree size. In addition to initial tree diameter or basal area, significant explanatory variables are crown class, topographic position and degree of ground incline. Plots illustrate the differing growth patterns of the 15 tropical mixed/moist forest species. Two species exhibit exceptional growth. Buchenavia capitata (Vahl) Eichl. has basal area growth peaking at 87 cm2 year−1. The Manilkara bidentata (A. DC.) A. Chev. data show growth rates in excess of 60 cm2 year−1 and the Chapman-Richards function indicates growth potential to a peak of 122 cm2 year−1.

Moment expressions and summary statistics for the complete and truncated weibull distribution

Traditionally, the moments of the Weibull distribution have been calculated using the standard Weibull (Johnson and Kotz, 1970) . This article will expand on that idea and cover the truncated cases for the standard Weibull distributions. Also, the same techniques used for the standard form will be used to derive the moment expressions for the three-parameter complete and truncated Weibull distributions. The summary statistics are then calculated from the moment expressions. Weibull moments involve the gamma and incomplete gamma functions.

Diameter measurement in bald cypress

Abstract The usual practice of measuring diameter at 4.5 feet (1.3 m) or D bh is meaningless in wetland tree species such as bald cypress ( Taxodium distichum (L.) Rich.), due to the presence of fluted basal swells. Since buttress dimensions usually have no consistent relation to volume or form in the tree, the current practice among life-sciences professionals is to measure stem diameter 18 in (50 cm) above ‘pronounced’ butt swelling. This measure is termed normal diameter ( D n ). This paper contrasts the use of six fixed-height diameter-measurement points ranging from 6 ft (1.8 m) to 11 ft (3.4 m) against D n (a variable-height measurement point) for predicting cubic volume. Results show an increase in precision using the upper five fixed-height measurements over D n and a considerable increase in precision using diameter measured at 10 ft (3.0 m) and 11 ft (3.4 m). Since results improved only slightly using diameter measured at 11 ft (3.4 m) over 10 ft (3.0 m), diameter at 10 ft ( D 10 ) is recommended as a better alternative than D n for working with cypress.

Dendroecological analysis of a Fitzroya cupressoides and a Nothofagus nitida stand in the Cordillera Pelada, Chile

Abstract Lumbering of Fitzroya cupressoides in Chile began in 1599 and continued until 1976, when the species was declared a national monument and cutting of live trees was prohibited. Today, F . cupressoides is threatened; many of the remaining stands in the coastal range appear to be declining, with a predominance of standing dead stems and patchy, sparse regeneration. We performed tree-ring analysis on a F . cupressoides stand and a nearby Nothofagus nitida stand, in the Cordillera Pelada, of coastal Chile (40°S) in order to examine the ecological history of two stands in the montane forest. Our analysis demonstrates that the F . cupressoides stand has undergone several periods of growth release and disturbance; the last 34 years of the chronology show a trend of increasing growth. In contrast, after 1865 radial growth of the N . nitida stand is fairly constant and steady. Radial growth of these two species is highly correlated with spring rainfall. November rainfall of the current growing season proved to be the best growth predictor of F . cupressoides , whereas current June and December rain, and December rain of the past growing season best predicted growth of N . nitida . Although episodic disturbances have occurred, the chronologies demonstrated that these stands are vigorous, despite the presence of dead stands nearby. These results do not support the idea that climatic deterioration is responsible for the decline of F . cupressoides during the past 77 years. La tala de F. cupressoides en Chile empezo en 1599 y continuo hasta 1976, cuando la especie fue declarada monumento nacional y la corta de arboles vivos fue prohibida. Esta especie es hoy considerada vulnerable. Muchos rodales que subsisten en las cumbres de la cordillera de la costa (40–42°S) parecen estar en declinacion con una predominancia de individuos muertos en pie. La regeneracion de F . cupressoides esta limitada a algunos rodales intervenidos. En este estudio se llevo a cabo un analisis de anillos de crecimiento de F . cupressoides y de N. nitida en dos rodales de la Cordillera Pelada (800–900 m), en la costa de Chile a 40°S, con el proposito de reconstruir la historia de estos bosques montanos en la cordillera de la costa. El analisis sugirio que el rodal de F . cupressoides ha sufrido varios periodos de liberacion de crecimiento y perturbacion. Los ultimos 34 anos de la cronologia demuestran una tendencia de crecimiento alto. Por otra parte, despues de 1865, el crecimiento del rodal de N . nitida es medianamente constante. El crecimiento de las dos especies se correlaciona fuertemente con las precipitaciones de primavera registradas en una estacion al sureste del area de estudio. La lluvia del mes de noviembre del ano anterior fue el mejor predictor de la cronologia de F . cupressoides , mientras que las lluvias de junio y diciembre del ano actual y la lluvia de diciembre de los dos anos anteriores predicen la cronologia de N . nitida . A pesar de la presencia de disturbios ocasionales, y la existencia de rodales vecinos compuestos de arboles muertos y de alta mortandad en rodales maduros, las cronologias demuestran que los rodales estudiados de F . cupressoides y de N . nitida estan saludables. Estos resultados no apoyan la idea de que el deterioro del clima podria ser responsable por la reduccion de F . cupressoides durante los ultimos 77 anos.

Effects of global climate change on biodiversity in forests of the Southern United States

Climate has not been stable in the past. Fluctuations of pine (Pinus) pollen in a 50,000-year sequence from Lake Tulane in Florida indicate that major vegetation shifts occurred during the last glacial cycle. Phases of pollen dominated by pine (indicating a wet climate) were interspersed with periods with plentiful oak (Quercus), ragweed, and marsh elder (Ambrosia type) populations (Grim et al., 1993). During the Holocene (i.e., the last 12,000 years), climate has fluctuated with periods of cooler, warmer, wetter or drier weather than at present. The greatest changes in climate probably occurred during deglaciation, approxiamtely 12,500 to 11,000 years ago. However in parts of the United States great shifts in plant distribution and composition occurred during the past 120 years, mainly resulting from anthropogenic factors (Miller and Wigand, 1994). From 1550 to 1850 a small ice age caused widespread starvation in Europe. Living things have been able to adapt to the warming since then, but widespread, rapid warming could be disastrous (Fajer and Bazzaz, 1992).

Models to Implement a Sustainable Forest Management - An Overview of the ModisPinaster Model

For a long period, practical recommendations for forest management were based upon experience gained through trial and error experimentation, observation and an understanding of density effects on tree growth within the stand. As stated by Zeide (2008), the limitations of the traditional empirical approach coupled with improvements on modelling efforts led to a change of procedures from forestry to forest science, this being defined by the author, as a new development relying on reasoning to produce the optimal system of forest management aimed at satisfying human needs and preserving nature at the same time (though not at the same place). Nowadays, the use of mathematical models for tree and stand growth dynamics is the recommended scientific approach to test for alternative management options under a Sustainable Forest Management (SFM) concept and to help solve practical problems such as the appropriate range of stand densities, the thinning prescriptions and rotation ages that allow for a given goal. Assessment of volume and biomass growth, for a given period, or of yield and carbon stock at a point in time becomes a straightforward procedure as long as there are proper equations available, for the species and region of study. Central to the successful implementation of research findings of sustainable forest management is their efficient transfer from the researcher to the manager (Farrell et al., 2000). In this context, there is a strong need for easily accessible programs to run various and numerous simulations in a convenient and flexible way. There are different possible approaches to build a simulation system, each having advantages and drawbacks. One is to build a specific tool for each model. Development can be fast when the objectives of the model are well defined, its structure remains simple and there is no need for complex outputs and interfaces. This approach nevertheless results in building many prototypes

Patterns of diametric growth in stem-analyzed laurel trees (Cordia alliodora) in a Panamanian forest

Abstract Based on cross-dated increment cores, yearly diameters of trees were reconstructed for 21 laurels (Cordia alliodora) growing in a natural secondary forest on Gigante Peninsula, Panama. From this sample of dominant-codominant trees, ages were 14–35 years with an average of 25 years. Growth typically slowed at 7 years old, indicating effects of competition from closure of gaps in the canopy. Rate of growth in diameter was modeled using the Bertalanffy-Richards growth function. Four patterns of growth were detected, of which 57% were sigmoidal, 19% were convex, 10% were monomolecular, and 14% were inverse sigmoid. Resumen Con base de testigos fechados de madera, diámetros anuales se reconstructaron para 21 árboles de laurel (Cordia alliodora) creciendo en un bosque natural secundario en la Peninsula Gigante, Panama. De esta muestra de arboles dominantes-codominantes, los edades varían de 14 a 35 años con un promedio de 25 años. Típicamente el crecimiento de los árboles disminuó a siete años de edad, señalando los efectos de competencia debido de la cierre de los claros en el dosel. La tasa de crecimiento diamétrico de los árboles se modeló usando la function de crecimiento Bertalanffy-Richards. Cuatro patrones de crecimiento se encontraron; 57 por ciento de los patrones eran sigmoideos, 19 por ciento eran convexos, 10 por ciento eran monomoleculares, y 14 por ciento eran sigmoideos inversos.