Se describió la composición y estructura florística del bosque amazónico de tierra firme del sector Alto Madera de la provincia centrosureña (fide Navarro). Se instalaron cinco parcelas de una hectárea (100x100 m), entre 140 a 156 m de altitud y geográficamente esta de 9 °55'a 10°19'S y 65°34' a 65°46'O; donde, se evaluaron e identificaron todos los árboles y lianas ≥10 cm de DAP. La densidad registrada fue de 480 (±13) arboles/ha y la diversidad promedio fue 152 (±8) especies/ha, 105 (±4) géneros/ha y 45(±2) familias/ha, basados en la evaluación de 2398 árboles y 137 lianas en 5 ha. La estructura se presentó en forma de J invertida, con mayor cantidad de individuos en las clases menores y a medida que aumenta el tamaño el número de individuos disminuye. En este bosque, las especies de mayor importancia ecológica (IVI) fueron Attalea vel. sp. nov. (palla) y Peltogyne heterophylla (morado), seguida de Euterpe precatoria (asaí), Pseudolmedia laevis (nuí peludo), Tetragastris altissima (isigo colorado), Tachigali vasquezii (palo santo colorado), Brosimun lactescens (quecho verde) y Bertholletia excelsa. En conclusión, el bosque de tierra firme del Alto Madera, es el bosque de mayor diversidad arbórea en Bolivia. No obstante, los valores se encuentran en el rango de diversidad para sus latitudes. Además, presentan composición florística diferente a otros bosques amazónico de tierra firme, la dominancia de la palla (Attalea vel. sp. nov.) y el morado (Peltogyne heterophylla) entre otras especies exclusiva le confieren una particularidad florística y fisionómica a esta formación forestal.

We describe the composition and floristic structure of the terra firme Amazon forest of the Alto Madera sector of the Centro-sureñan province (fide Navarro). Five plots of one hectare (100x100 m) were installed at an altitude of 140 to 156 m at the geographically locale 9 "55' to 10°19'S and 65°34' to 65°46'W; with all trees and lianas ≥ 10 cm diameter measured. The density is 480 (± 13) trees/ha and the diversity is greater than at other sites in Bolivia, with an average of 152 (± 8) species/ha, 105 (± 4) genera/ha and 45 (± 2) families/ha, based on the evaluation of 2398 trees and 137 vines. The structure is pyramidal or in the form of an inverted J, with a greater number of individuals in the smaller classes. In this forest, the most ecologically important species are Attalea sp. nov. (palla) and Peltogyne heterophylla (morado), followed by Euterpe precatoria (asaí), Pseudolmedia laevis (nuí peludo), Tetragastris altissima (isigo colorado), Tachigali vasquezii (palo santo colorado), Brosimum lactescens (quecho verde) y Bertholletia excelsa. In conclusion, the Alto Madera terra firme forest is the forest with the greatest tree diversity in Bolivia. However, the values are in the range of diversity of forests of similar latitudes. In addition, they have a floristic composition different from other Amazon forests of the terra firme, the dominance of the palla (Attalea sp. nov.) and the Purple Heart (Peltogyne heterophylla) among other exclusive species giving this formation a floristic and physiognomic particularity to this forest formation.

ABSTRACTFire can change the species composition, diversity, and structure of savanna vegetation, thus altering growth and mortality rates. Such changes in the woody vegetation of burned savanna forest were evaluated over four years in comparison to unburned savanna forest. All woody plants with a diameter at breast height > 10 cm were measured in 100 permanent plots. Six months later, 38 of these plots were burned. Three and a half years later, all surviving individuals were re-sampled. Species richness, diversity, and the number of individuals did not change in the burned plots, although they had significantly higher (p < 0.05) increases in basal area and mortality rates (5.1% year-1) than the unburned plots (3.0% year-1).Tachigali vulgarishad the greatest post-fire increase in basal area (53%). The results indicate that fire alters the dynamics and structure of the savanna forest, excluding the less fire-tolerant species and smaller individuals (? 15cm). Tachigali vulgaris is a key species for the recovery of savanna forest biomass due to its considerable post-fire gains in basal area, at least over the short term due to its short life cycle. It follows that frequent burning of savanna forest would result in a marked change in the species composition and structure of its woody vegetation.

Stocks of dead wood or necromass represent an important portion of biomass and nutrients in tropical forests. The objectives of this study were: 1) to evaluate and compare the necromass of "terra firme" and lowlands forests, (2) to study the relationship between necromass, above-ground biomass and wood density, and (3) to estimate the necromass of the department of Madre de Dios, Peru. Stocks of necromass and above-ground biomass were estimated at three different locations using permanent plots and line intercept transects. The average volume of necromass for the three sites was 72.9 m3 ha-1 with an average weight varying between 24.8 and 30.7 Mg ha-1, depending on the estimations of dead wood density used for the calculations. Terra firme forests had significantly higher stocks of necromass than lowland forests. The amount of necromass was 11% of the total above-ground biomass in Madre de Dios forests. The total stock of carbon stored in dead wood for the entire department of Madre de Dios was estimated to be approximately 100 mega tonnes of carbon. This is ten times more than the annual fossil fuel emissions of Peru between 2000 and 2008. The substantial stocks of necromass emphasize the importance of these types of field studies, considering that this component of tropical forest carbon cannot be detected using other methods such as satellite remote sensing.

La cantidad de madera muerta o necromasa representa una importante porción de la biomasa y de los nutrientes en los bosques tropicales. Los objetivos de este estudio son: 1) hacer una evaluación y comparación entre la necromasa de los bosques de altura o tierra firme y los bosques inundables o bajíos, (2) estudiar las relaciones entre la necromasa, la biomasa aérea y la densidad de madera del bosque, y (3) proporcionar una primera estimación de la necromasa para todo el departamento de Madre de Dios. La necromasa gruesa y la masa aérea vegetativa fueron estudiados en tres diferentes lugares utilizando parcelas permanentes y líneas de intersección. El promedio del volumen de madera muerta gruesa fue de 72,9 m³ ha-1, con un peso entre 24,8 y 30,7 Mg ha-1 dependiendo de la densidad de madera muerta usada en los cálculos. Los bosques de tierra firme contienen significativamente más madera muerta que los bosques inundables. La necromasa constituye 11% de la masa aérea vegetativa almacenada en los bosques de Madre de Dios. Finalmente, se estima que el departamento de Madre de Dios contiene alrededor de 100 mega toneladas de carbono en su madera muerta. Este valor es bastante alto, siendo diez veces más que la emisión anual de combustibles fósiles de Perú entre 2000 - 2008. Esta substancial porción de la necromasa enfatiza la importancia de estos tipos de estudios de campo, considerando que este componente de carbono en el bosque tropical no se logra detectar con otros métodos como la detección remota por satélites.

Nas últimas décadas, considerável parcela da floresta amazônica tem sido transformada em pastagens que, em função da baixa fertilidade natural dos solos e do manejo deficiente, decrescem rapidamente em produtividade e são abandonadas, dando lugar a uma sucessão secundária arbórea adaptada à baixa disponibilidade de nutrientes. O objetivo deste estudo foi obter informações sobre a eficiência no uso dos nutrientes por espécies arbóreas freqüentes nesses ambientes degradados, após calagem e aplicação de fosfato. O experimento realizado numa área de sucessão secundária com seis anos de idade, consistiu na aplicação de quatro tratamentos: controle; aplicação de fósforo (P); aplicação de fósforo e calcário (P+Cal); e aplicação de fósforo, calcário e gesso (P+Cal+G). As determinações das taxas de fotossíntese, bem como as coletas de amostras de solo e de folhas foram realizadas oito meses após a aplicação dos tratamentos. A aplicação do corretivo e do fosfato favoreceu o desempenho das espécies nos tratamentos P+Cal e P+Cal+G. Bellucia grossularioides acumulou mais N, P e Zn, enquanto que Laetia procera acumulou mais Ca e Mn. Vismia japurensis foi a espécie mais eficiente no uso dos nutrientes, em função dos altos valores da taxa fotossintética; apresentou baixos teores foliares de P quando comparada com Bellucia grossularioides, sugerindo ser uma espécie bem adaptada a ambientes com baixa disponibilidade de nutrientes, como ocorre em áreas degradadas na Amazônia.

Large areas of Amazonian forest have been converted to pastures over the last two decades. Low soil fertility and mismanagement results in a rapid decline in net primary productivity leading the pastures to be abandoned, and woody vegetation adapted to low nutrient conditions colonize the areas. The objective of this study was to examine nutrient use efficiency, following liming (calcium) and phosphorus addition by three of the most frequent colonizing species. The experiment conducted on a six year-old secondary forest, consisted of four treatments: control; phosphorus addition (P); phosphorus and lime addition (P+Cal); and phosphorus, lime and gypsum addition (P+Cal+G). Leaf gas exchange, soil and leaf nutrient concentration were determined eight months after the treatment application. There was a significant response by species to the addition of phosphorus and lime (P+Cal and P+Cal+G). The species, Bellucia grossularioides accumulated more N, P and Zn in the leaves, while Laetia procera accumulated more Ca and Mn. The species Vismia japurensis had higher nutrient use efficiency, as a function of the higher photosynthetic rates. Vismia japurensis presented lower P concentrations than Bellucia grossularioides, suggesting that is well adapted to environments low in nutrients, as this species often occurs in degraded areas in Amazonia.