Tree architecture and secondary tropical rain forest development: A case study in Araracuara, Colombian Amazonia

Abstract

Summary Four successional forests, the oldest 30 years old, and a mature forest on the low terrace of the Caqueta river (Colombian Amazonia), were analysed architecturally. The architecture of these secondary forests was largely determined by species of Vismia , Miconia and Inga reaching their maximal crown expansion during the first 30 years of secondary forest development. Forest profiles were drawn to scale, indicating the development phase of every tree (Dbh > 5 cm). Three development phases were distinguished according to crown architecture, i.e. potential trees, trees of the present and trees of the past. These development phases were used to determine the dynamics of the species within the secondary forest A first approximation of the secondary forest development in Araracuara is as follows: 1. Within seven years a set of trees of the present (Vismia glaziovii and Miconia minutiflora) develop a low ( 2. Between seven and eleven years Vismia japurensis and Vismia macrophylla develop a higher (10–15 m) canopy of trees of the present making survival of the previous set of the present impossible. Again potential trees of other species are present, some of them emerging. 3. Around 20 years Miconia poeppigii, Miconia myriantha, Jacaranda copaia and several Inga species form a still higher (c. 20 m) canopy of trees of the present, making survival of the Vismia set almost impossible. Most potential trees in this development phase are lower than the trees of the present, some are still emerging, i.e. Cecropia spp. A lower (ca. 10m) set of the present is formed by several Miconia species already present from the initiation of the succession ( Miconia prasina, Miconia pilgeriana, Miconia punctata, Miconia splendens ) and Piper arboreum 4. Around 30 years the canopy of Miconia and Inga species starts to degenerate. Potential trees grow into the gaps. 5. In the mature forest the formation of gaps by trees of the past is the most important factor in the regeneration From every tree species encountered in the transects documented by profiles, the basic branching pattern, i.e. architectural model (sensu HALLE et al. 1978), was determined. For every transect an architectural spectrum was made. These spectra show the numbers of individuals and species having the same architectural models. By approximation, the results are broadly in agreement with earlier research from French Guyana. Young secondary forests have many individuals with Rauh's model, together with many individuals with Roux's model, and few individuals with Troll's and Massart's model, and certainly few species with those models. In mature forest there is a large number and great variety of Troll's model, Massart's model and often Aubrevilles model, and still quite a number of individulas with Rauh's model. Roux's model is found in the understorey of the mature forest