Extracting the NWI freshwater emergent wetlands on CAPES and associated refuges

Definition of freshwater wetlands

We define freshwater wetlands as follows:

1. Using version 2.0 of the state-by-state National Wetlands Inventory (NWI) data, we extract all palustrine, lacustrine littoral, and riverine emergent-dominated wetlands (i.e., PEM*, L2EM*, and R1EM*, and R2EM*). Note that all lacustrine and riverine emergent wetlands are considered “nonpersistent”, meaning emergent hydrophytes are typically present only during the growing season.
2. We attempt to distinguish between impounded and unimpounded “natural” wetlands using the “Diked/Impounded” special modifier from NWI, though we are uncertain of its completeness or accurary in identifying impounded freshwater wetlands.
   
3. We restrict our query to the CAPES region and the current administrative boundaries of refuges within the CAPES boundary, based on the USFWS Cadastral Layer(as of December 2019).