Effects of land use on soil C02 flux in the Paramo de Guerrero, Colombia

Abstract

The Andean paramo is an important global carbon sink and has a fundamental ecological function of capture, regulation and supply of water resources. The soil CO2 efflux is a natural process through which the carbon is released into the atmo sphere by molecular diffusion. The aim of this study was to establish the effect of different land use and soil managements practices over CO2 efflux in the Paramo de Guerrero, using the soil respiration chamber technique. We evaluated five differ ent land covers present in the Paramo de Guerrero (paramo vegetation, pasture, two tillage cover and potato crop). Our results show that soil respiration was lower in the paramo (0.42 g CO2 m-2 h-1) than in the others land uses, probably due to the higher moisture content (57.1% on average). The tillage practices showed a primary physical effect, continued by the increase of the velocity of biological and chemical processes drived by soil microorganisms, such as microbial respiration and organic matter mineralization. This study demostrates that moisture and soil temperature were not the main drivers of CO2 flux in the conditions of the Paramo de Guerrero, but the agricultural management and the land use affect differentially the accumulation and release dynamics of soil organic carbon to the atmosphere.

The importance of and need for rapid hydrologic assessments in Latin America

“…Although, in most instances, these differences were not statistically significant at the landscape scale, it is important to note that the range in the concentrations was almost always greater in the impacted watershed, an indication of the degree of variability within the stream network and likely a result of the variability in land uses within the watershed. Land uses at the impacted site differed from the lower to the upper part of the watershed and included potato crops and pasture for grazing at lower elevations and shrubland and dense grassland at higher elevations (Peña‐Quemba et al, ). In particular, concentrations of DOC, NO 3 , and PO 4 were lower near and around the wetland complexes of the impacted site (i.e., the headwater of Guandoque Creek), but the complexity of the land fragmentation at the impacted site prevented us from singling out the connection between land cover and stream water quality.…”

“…Although monitoring data are considered the base of management decisions in the tropics (Castello et al, ), the lack of consistent monitoring programmes often forces researchers and decision makers to use surrogates for water quality in high‐elevation regions (including satellite imagery as a measure of erosion and soil loss [Wantzen & Mol, ] and percent ground cover as a proxy for water quality states [Oyague Passuni & Maldonado Fonkén, ]). Few journal‐published studies have examined chemical effects of land‐use change in páramos (Farley, Kelly, & Hofstede, ; Peña‐Quemba et al, ), and their observations have mostly focused on soil quality and soil C losses, but not water quality. We suggest that synoptic water sampling and targeted experimental work (as described below) can provide a useful path towards understanding system dynamics in locations where rapid assessments are necessary and long‐term data are either limited or simply non‐existent.…”

“…Given their large proportion among all rivers in a network, headwater streams are known to contribute large amounts of CO 2 (Crawford, Stanley, Dornblaser, & Striegl, ) and CH 4 (Crawford et al, ) to the atmosphere. These fluxes remain virtually unknown in páramos, where soils are known to have carbon contents even >40% (Comas et al, ; Hribljan et al, ; Peña‐Quemba et al, ). Carbon cycling dynamics in these high‐elevation landscapes are likely to be important to both regional and global carbon cycles and represent a knowledge gap in Latin American science.…”

“…Downstream from the wetlands' land cover is mainly pasture ( Pennisetum clandestinum ) and potato crops ( Solanum tuberosum ) with portions of bare soil between planting rotations. Intense agricultural activity has been conducted in the impacted site for over 40 years (Peña‐Quemba, Rubiano‐Sanabria, & Riveros‐Iregui, ). Both sites are underlain by the Guadalupe Group, a late Cretaceous sequence of shales and sandstones, which extend along much of the Bogotá Savanna and the eastern flank of the Colombian Andes (Moreno‐Torres & Ruiz‐Rodriguez, ).…”

A concerted research effort to advance the hydrological understanding of tropical páramos

“…Carbon dioxide dynamics have also been assessed using portable soil respiration chambers in field experiments. Using this technique, agricultural management and land‐use changes were identified as the main drivers of soil‐atmosphere exchange of CO 2 in páramos of Guerrero (Colombia) (Peña‐Quemba et al, 2016). The authors additionally stated that the easy decomposition of organic matter in páramos soils turns them into carbon sinks.…”