Latitudinal Trends in Soil Organic Matter and Primary Production in Baldcypress Swamps of North America.

Carbon storage and production levels vary across the ranges of ecosystems in response to differences in climate, land-use, and hydrology. Baldcypress (Taxodium distichum) swamp is a forested wetland type with a wide-ranging distribution in the southeastern part of North America. To study geographic patterns of carbon storage and production, long-term study sites were established in swamps at seven latitudes in the Mississippi River Alluvial Valley from Illinois to Louisiana, and elsewhere in outlying areas (e.g., Texas and Delaware). Based on long-term studies from 2002-2013, leaf and root production, organic matter storage, and tree height were higher in the middle of the range, and lower in the northern and southern parts of the range, and these patterns are likely due to differences in temperature and water availability. IPCC climate change models suggest that this region may experience future episodes of extreme flooding and/or supra-annual drought, along with climate warming. Soil environment changes related to reduced water availability because of drought or land-use activities such as water abstraction would likely shift the pattern of soil organic carbon and primary production northward. Knowledge of the responses of baldcypress swamps to climate differences across the latitudinal range can provide predictive information on potential shifts of future swamp ecosystem functions.