Forest Structure, Diversity and Dynamics in Terra Firme and Igapó Gallery Forests in the Colombian Orinoco Basin

Abstract

Studies of dynamics and biomass accumulation are essential for understanding forest functioning and productivity. They are also valuable when planning strategies for the conservation and sustainable use of natural resources. This study was conducted in five one-hectare plots of gallery forest in the Orinoco basin (three in terra firme and two in igapó floodplains), located in the Tomogrande Reserve, Santa Rosalía municipality, Vichada, Colombia. The differences between these forest types were determined and quantified considering diversity, floristic composition, aboveground biomass, forest dynamics and the influence of soils’ physicochemical composition. Terra firme forests were more diverse (Fisher’s α = 30.4) and had higher mortality and recruitment rates than igapó forests but there were no significant differences in stem turnover rates between forest types. Relative tree growth rate was also higher in terra firme than in igapó, but the opposite was found for biomass change (1.47 t/ha/year in igapó), resulting in an average carbon accumulation rate of 0.33 t/ha/year in terra firme and 0.66 t/ha/year in igapó. Igapó forest has high carbon accumulation potential given the high wood density of certain dominant species. Igapó soils contained a higher concentration of sand, silt, phosphorus and potassium ions, while terra firme soils had a higher clay content with lower pH. In general, the demographic and growth rates were consistent with those described for Amazonian forests. This study highlights the potential of igapó forest in the Orinoco basin as important carbon sinks, which should be included in the management and conservation strategies for this region.

Contrasting drivers of aboveground woody biomass and aboveground woody productivity in lowland forests of Colombia

“…The mean annual temperature (MAT) of plots was 24.7 ± 0.6°C (mean ± SD), ranging from 21.5 to 25.5°C, while the mean annual precipitation (MAP) of the plots was 3076.4 ± 299.9 mm year −1 , ranging from 1797 to 3716 mm year −1 . Eight plots were located in the Orinoquia region (González‐Abella et al 2021) and 31 in the Amazonia region of Colombia (see Data availability link). Plots were censused between 2005 and 2021.…”

“…This finding suggests the need for further analyses to assess whether the observed patterns supporting diversity as a likely important explanatory factor of the spatial and temporal AGB variation are due to differences in the spatial extent (i.e. meso‐ or large spatial scales), and/or the amplitude of the edaphic gradient and flooding (González‐Caro et al 2021). Therefore, assessing the importance of both taxonomic and evolutionary diversity on determining AGB and AWP, including both flooded and non‐flooded terra firme forests, will help to disentangle the extent to which the evolutionary history of plant communities can be used to explain the importance of biological mechanisms in determining forest structure and function.…”

Plant, bird, and mammal diversity of the Tomogrande field station, Vichada, Colombia

“…There have been 22 research projects conducted in Tomogrande, ranging from short field trips conducted by experts, undergraduate and master theses spanning several months (Correa-Gómez & Stevenson, 2010;Góngora Blanco, 2012;Sánchez Medina, 2017), to longterm projects that were established since the creation of the reserve in 2009 (Stevenson, 2016;. Five one-ha permanent vegetation plots have been established, three in terra firme forests and two in flooded forests (Aldana et al, 2017;Casas, 2013;Correa et al, 2015;González-Abella et al, 2021;Stevenson et al, 2018). We also have four research trails within the terra firme forests to study plant, bird, and mammal diversity and primate behavior (Góngora Blanco, 2012;Sánchez Medina, 2017;Stevenson, 2016).…”

“…and F.C) and some determinations were made by Dairon Cárdenas and specialists at the National Colombian Herbarium. For this purpose, two specimens were collected from each species or morphospecies of trees and lianas, with diameter at breast height > 10 cm, registered in our permanent plots (including 156 named species and 15 morphospecies determined mostly at the genus level) (González-Abella et al, 2021). [3565][3566][3567][3568][3569][3570][3571][3572][3573][3574][3702][3703][3704][3705][3706][3707][3708][3709][3710].…”