A bit of background: While I was studying abroad in Australia a little over a year ago (Fall 2012), I carried out a research project about soil organic carbon stocks in the coastal wetlands of North Stradbroke Island. This project (called a TRP), is meant to just be a few days of fieldwork followed by a written report and a short presentation. It's a great introduction to individual research projects, but for me it actually ended up being a major inspiration for some of my future classes and research!
While researching for my TRP I was introduced to the concepts of carbon sequestration and storage in soils. Wetlands, as it turns out, are some of the best wetlands for capturing and storing atmospheric carbon. This high storage is achieved because sedimentation from flood pulsing and accumulation of high levels of aboveground biomass result in a large amount of carbon accumulation into the soil. Then, in contrast to tropical rainforest systems where there is also a high level of carbon input to the soil, carbon in wetland soil remains stored because the water-laden soils become anoxic and prevent decomposition of these organic compounds.
Due to these conditions, wetlands have been found to store a globally significant store of carbon, and are thought to play an important role in global climate regulation. In a recent paper, the following figure was presented to show the potential role of wetlands (and shallow marine seagrass beds) in carbon burial relative to other highly vegetated and more heavily studied systems.
With this is mind, I decided to look up a few other papers about soil carbon storage in the Pantanal and found a couple of interesting journal articles published within the last few years. The first paper, from 2010, looks into changes in the carbon stocks in the northern region of the Pantanal up to the Amazon basin between 1970 and 2002. It was found, through analysis of a variety of environments, that the Pantanal was losing the most carbon of any ecosystem type in Brazil. The numbers found were 0.94 Mg C/ha to 1.16 Mg C/ha. It is very hard to put these numbers into context because of the need to convert a lot of units, but what is more interesting and important to our understanding and conversation surrounding carbon dynamics in the Pantanal is the qualitative assessment that came along with the study. It was found that much of this carbon was lost due to cattle ranching activities in the area, and it was noted that losses could have been substantially greater if there was substantial unnatural change to hydrology in the region. This has not largely occurred yet in the Pantanal, but as others have posted about with the hidrovia project among others, future plans to dam or otherwise manipulate hydrology could thus have a major impact of soil carbon in the Pantanal.
A second paper I found interesting compared sedimentation from flood pulsing in the Pantanal to that of the Orinoco Flood plain in Colombia. This study looked specifically at shallow seasonal lakes and their carbon storage potential during flooding events. The findings of the study indicate that the Pantanal is actually storing less carbon that the Orinoco plains because of different geomorphology in the shallow seasonal lakes. Those of the Orinoco plains have a more concave shape and a greater number of flooded days that those of the Pantanal, and therefore a greater amount of accumulated sediment during the flood pulsing that comes when rainfall increases in the wet season. While at first glance this finding might appear to suggest that Pantanal might be of less conservational importance, it is also important to consider that the Pantanal would have more trouble returning to natural levels of carbon storage should human induced perturbations (such as changes to hydrology or land use) cause a significant loss in these carbon stocks.
As we go forward with our studies of the Pantanal, thinking about changes to water regimes, land use, tourism, invasive species, and many other topics, it would be interesting to consider the impact these changes may have on carbon dynamics in a system that may play an important role in climate regulation amidst this century of impending climate warming.
-Cole
Sources:
1) Maia, Stoecio MF, et al. "Soil organic carbon stock change due to land use activity along the agricultural frontier of the southwestern Amazon, Brazil, between 1970 and 2002." Global change biology 16.10 (2010): 2775-2788.
2) Johnson, Mark S., et al. "Soil CO2 dynamics in a tree island soil of the Pantanal: the role of soil water potential." PloS one 8.6 (2013): e64874.
3) Vega, Luisa F., et al. "Does Flood Pulsing Act as a Switch to Store or Release Sediment-Bound Carbon in Seasonal Floodplain Lakes? Case Study from the Colombian Orinoco-Llanos and the Brazilian Pantanal." Wetlands 34.1 (2014): 177-187.
(Source: Mcleod, Elizabeth, et al. "A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2."Frontiers in Ecology and the Environment 9.10 (2011): 552-560.)
With this is mind, I decided to look up a few other papers about soil carbon storage in the Pantanal and found a couple of interesting journal articles published within the last few years. The first paper, from 2010, looks into changes in the carbon stocks in the northern region of the Pantanal up to the Amazon basin between 1970 and 2002. It was found, through analysis of a variety of environments, that the Pantanal was losing the most carbon of any ecosystem type in Brazil. The numbers found were 0.94 Mg C/ha to 1.16 Mg C/ha. It is very hard to put these numbers into context because of the need to convert a lot of units, but what is more interesting and important to our understanding and conversation surrounding carbon dynamics in the Pantanal is the qualitative assessment that came along with the study. It was found that much of this carbon was lost due to cattle ranching activities in the area, and it was noted that losses could have been substantially greater if there was substantial unnatural change to hydrology in the region. This has not largely occurred yet in the Pantanal, but as others have posted about with the hidrovia project among others, future plans to dam or otherwise manipulate hydrology could thus have a major impact of soil carbon in the Pantanal.
A second paper I found interesting compared sedimentation from flood pulsing in the Pantanal to that of the Orinoco Flood plain in Colombia. This study looked specifically at shallow seasonal lakes and their carbon storage potential during flooding events. The findings of the study indicate that the Pantanal is actually storing less carbon that the Orinoco plains because of different geomorphology in the shallow seasonal lakes. Those of the Orinoco plains have a more concave shape and a greater number of flooded days that those of the Pantanal, and therefore a greater amount of accumulated sediment during the flood pulsing that comes when rainfall increases in the wet season. While at first glance this finding might appear to suggest that Pantanal might be of less conservational importance, it is also important to consider that the Pantanal would have more trouble returning to natural levels of carbon storage should human induced perturbations (such as changes to hydrology or land use) cause a significant loss in these carbon stocks.
As we go forward with our studies of the Pantanal, thinking about changes to water regimes, land use, tourism, invasive species, and many other topics, it would be interesting to consider the impact these changes may have on carbon dynamics in a system that may play an important role in climate regulation amidst this century of impending climate warming.
-Cole
Sources:
1) Maia, Stoecio MF, et al. "Soil organic carbon stock change due to land use activity along the agricultural frontier of the southwestern Amazon, Brazil, between 1970 and 2002." Global change biology 16.10 (2010): 2775-2788.
2) Johnson, Mark S., et al. "Soil CO2 dynamics in a tree island soil of the Pantanal: the role of soil water potential." PloS one 8.6 (2013): e64874.
3) Vega, Luisa F., et al. "Does Flood Pulsing Act as a Switch to Store or Release Sediment-Bound Carbon in Seasonal Floodplain Lakes? Case Study from the Colombian Orinoco-Llanos and the Brazilian Pantanal." Wetlands 34.1 (2014): 177-187.
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