Rafael Calama

Bio: Rafael Calama is an academic researcher from Center for International Forestry Research. The author has contributed to research in topics: Climate change & Forest management. The author has an hindex of 26, co-authored 71 publications receiving 1886 citations.

Interregional nonlinear height-diameter model with random coefficients for stone pine in Spain

Abstract: An individual-tree height–diameter model was developed for stone pine (Pinus pinea L.) in Spain. Five biparametric nonlinear equations were fitted and evaluated based on a data set consisting of 86...

Multilevel linear mixed model for tree diameter increment in stone pine (Pinus pinea): a calibrating approach

Abstract: Diameter increment for stone pine (Pinus pinea L.) is described using a multilevel linear mixed model, where stochastic variability is broken down among period, plot, tree and within-tree components. Covariates acting at tree and stand level, as breast height diameter, density, dominant height or site index are included in the model as fixed effects in order to explain residual random variability. The effect of competition on diameter increment is expressed by including distance independent competition indices. The entrance of regional effects within the model is tested to determine whether a single model is sufficient to explain stone pine diameter increment in Spain, or if, on the contrary, regional models are needed. Diameter increment model can be calibrated by predicting random components using data from past growth measurements taken in a complementary sample of trees. Calibration is carried out by using the best linear unbiased predictor (BLUP) theory. Both the fixed effects model and the calibrated model mean a substantial improvement when compared with the classical approach, widely used in forest management, of assuming constancy in diameter increment for a short projection period.

To grow or to seed: ecotypic variation in reproductive allocation and cone production by young female Aleppo pine (Pinus halepensis, Pinaceae).

Abstract: Age and size at the fi rst reproduction and the reproductive allocation of plants are linked to different life history strategies. Aleppo pine only reproduces through seed, and, as such, early female reproduction confers high fi tness in its infertile highly fi reprone habitats along the Mediterranean coast because life expectancy is short. We investigated the extent of ecotypic differentiation in female reproductive allocation and examined the relation between early female reproduction and vegetative growth. In a common-garden experiment, the threshold age and size at fi female reproduction and female reproductive allocation at age seven differed signifi cantly among Aleppo pine provenances of ecologically distinct origin. Signifi cant correlations among reproductive features of the provenances and the ecological traits of origin were found using different analytical tools. In nonlinear models of cone counts vs. stem volume, medium-sized trees (not the largest trees) produced the highest cone yield, confi rming that, at the individual level, early female reproduction is incompatible with fast vegetative growth. The contribution of founder effects and adaptation to contrasting fi re regimes may be confounding factors. But considering all traits analyzed, the geographical patterns of resource allocation by Aleppo pine suggest ecotypic specialization for either resource-poor (favoring early reproduction) or resource-rich (favoring vegetative growth) habitats.

Inter-regional variability in site index models for even-aged stands of stone pine (Pinus pinea L.) in Spain

Abstract: Variabilite inter-regionale des modeles de site index pour les peuplements reguliers de pin pignon (Pinus pinea L.) en Espagne. Les donnees de 96 analyses de tige et de 37 placettes permanentes de pin pignon (Pinus pinea L.) reparties dans quatre regions d'Espagne (Massif central. Plateau de Nord-Castille, Andalousie et Catalogue) ont ete utilisees pour le developpement d'un modele de croissance (hauteur dominante) pour chaque region. Les modeles sont compares entre eux afin de detecter des similarites ou des differences sur la croissance en hauteur entre les peuplements des quatre regions, ce qui pourrait justifier la necessite de construire des modeles regionaux pour Pinus pinea en Espagne. Pour comparer les modeles entre eux, des tests sur l'homogeneite de parametres et des analyses statistiques de biais ont ete utilises.

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

Modeling Forest Trees and Stands

Abstract: 1. Introduction.- 2. Tree Form and Stem Taper.- 3. Tree-stem Volume Equations.- 4. Tree Weight and Biomass Estimation.- 5. Quantifying Tree Crowns.- 6. Growth Functions.- 7. Evaluating Site Quality.- 8. Quantifying Stand Density.- 9. Indices of Individual-tree Competition.- 10. Modeling Forest Stand Development.- 11. Whole-stand Models for Even-aged Stands.- 12. Diameter-distribution Models for Even-aged Stands.- 13. Size-class Models for Even-aged Stands.- 14. Individual-tree Models for Even-aged Stands.- 15. Growth and Yield Models for Uneven-aged Stands.- 16. Modeling Response to Silvicultural Treatments.- 17. Modeling Wood Characteristics.- 18. Model Implementation and Evaluation.-