ABSTRACT Changes in coverage affect the activity of soil’s microbial communities, affecting the carbon and nitrogen cycle. The variability of biochemical properties in different coverages (native forest, forest plantation, silvopastoral system and pasture) located in the northwest of the Colombian Amazon was evaluated. Edaphic properties were determined as: organic carbon (OC), total nitrogen (TN), microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) using the fumigation method. A significant effect was found to land use × depth interaction for the variables moisture, pH, CO and MBC/OC ratio (p < 0.05), while MBC and dCO2 showed differences only for land use and NT, MBN and MBN/TN ratio at depth (p < 0.05). In general, when modifying the soil cover, changes were made in the chemical properties that affected the microbial activity.

ABSTRACT The objective of this study was to analyze the biological contribution to macroaggregate formation under cocoa agroforestry systems, as well as to evaluate the potential of macroaggregates to store carbon. The variation of the populations of macrofauna and the relationship with the morphology of aggregates was monitored in five agroforestry systems associated with cocoa established from different land uses, taking as reference the forest and pasture. Some cacao agroforestry systems favored the presence of macrofauna functional groups similar to the forest (p < 0.05). According to the principal component analysis, the effect of land use on macroaggregate formation is highly significant (p < 0.001) and explained 55% of the total variance. The macrofauna and macroaggregates showed significant covariation (RV = 0.22, p-value = 0.001). Biogenic macroaggregates contained more carbon when they came from agroforestry systems.

ABSTRACT The objective of this study was to evaluate the occurrence of the soil macrofauna in coffee production systems, as well as their relationship with edaphic properties. Therefore, two coffee production systems were selected: coffee plantations at full-sun with conventional management (Intensive) and shaded coffee plantations with organic management (Traditional). In each crop system, three soil samples were collected randomly, in the form of blocks (25 × 25 cm), to a soil depth of 10 cm. In total, 17,109 individuals were recorded in this study being the Oligochaeta group the most representative, regardless of the coffee production system. The average density of soil macrofauna was higher in traditional coffee plantations (p < 0.05) due to the higher density of Oligochaeta, Diplopoda and Blattodea. The traditional coffee plantations provided a better soil chemical fertility reflected in the principal component analysis. Furthermore, these chemical attributes probably could affect the occurrence of the soil macrofauna groups.

Resumo: O objetivo deste trabalho foi avaliar a macrofauna edáfica e os grupos taxonômicos bioindicadores associados a diferentes usos da terra na Amazônia colombiana. Doze arranjos agroflorestais foram estudados e comparados com a mata nativa e a pastagem. Para cada uso da terra, seis monólitos, divididos em quatro camadas (serrapilheira, e 0-10, 10-20 e 20-30 cm de profundidade) foram coletados aleatoriamente. As variáveis consideradas na análise do efeito dos usos da terra foram: indivíduos por metro quadrado, riqueza de ordens, índice de diversidade de Shannon e índice de equidade de Pielou. Os maiores valores de densidade e diversidade de macrofauna do solo ocorreram na floresta, em contraste com a pastagem. A análise dos componentes principais distinguiu os usos do solo de acordo com a diversidade da macrofauna, tendo separado a floresta nativa dos outros usos da terra. A análise de agrupamento indicou o potencial de alguns sistemas agroflorestais para conservar os valores de densidade e diversidade da macrofauna edáfica semelhantes aos da floresta. De acordo com a análise do valor do indicador, cinco grupos taxonômicos (Diplura, Pseudoscorpionida, Araneae, Chilopoda e Gastropoda), identificados como bioindicadores, estão associados a locais conservados, em razão da sensibilidade de suas populações.

Abstract: The objective of this work was to evaluate the soil macrofauna and the bioindicator taxonomic groups associated with different land uses in the Colombian Amazon. Twelve agroforestry arrangements were studied and compared with to the native forest and pasture. For each land use, six monoliths were randomly selected and divided into four layers (litter, and 0-10, 10-20, and 20-30 cm soil depths). The variables considered in the analysis of land use effects were: individuals per square meter, order richness, Shannon’s diversity index, and Pielou’s evenness index. The greatest values for soil macrofauna density and diversity occurred in the forest, in contrast with the pasture. The principal component analysis distinguished land use according to macrofauna diversity, separating the native forest from the other land uses. The cluster analysis indicated the potential of some agroforestry systems to conserve the values of soil macrofauna density and diversity similar to those of the forest. According to the analysis of indicator value, five taxonomic groups (Diplura, Pseudoscorpionida, Araneae, Chilopoda, and Gastropoda), identified as bioindicators, are associated with preserved sites because of the sensitivity of their populations.