Carbon Storage in Active Rice Fields and Aquaculture Ponds That Were Previously Mangroves
Abstract
Historically, a major portion of the world's mangrove swamps has been lost due to dredging, filling, draining, and today due to clearing for shrimp aquaculture. As one of the world's most efficient carbon sinks, substantial losses of its soil blue carbon occur with this transformation, estimated at 7 TgCO2eyr-1, globally. The State of West Bengal contains part of the world's largest contiguous mangrove forest, the Sundarbans, but also ranks as India's second highest shrimp producer. We examined soil carbon stocks in sites that previously supported mangroves within the Lot No. 126 region of West Bengal. Here mangrove swamps were first drained 60 years ago for rice cultivation. Later, the mangroves were deforested and drained for aquaculture. We sampled soils from 5 active shrimp ponds and 5 rice fields to a depth of ~50 cm. Both active shrimp ponds and rice fields have been ignored in past studies. The ponds were constructed 6-7 years ago and were sampled after a few days of drainage for maintenance. IPCC Guidelines for National Greenhouse Gas Inventories provide estimates for soil carbon loss from shrimp ponds created directly from mangroves, but there are no estimates for losses when mangroves are transformed to rice fields. Further, IPCC guidelines provide estimates for C stocks for irrigated OR rain fed rice fields but not for the mixed management regime that is employed in Lot No. 126. We believe that our measurements of soil carbon stocks in rice fields and active shrimp aquaculture ponds in Lot No.126 are the first for these types of wetland transformations. In this presentation, we will compare carbon stocks of mangroves to that of rice fields and shrimp aquaculture ponds to determine which results in greater soil C loss.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB048.0005S
- Keywords:
-
- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0442 Estuarine and nearshore processes;
- BIOGEOSCIENCES;
- 0469 Nitrogen cycling;
- BIOGEOSCIENCES