Inforain Ecotrust

Coquille Subbasin Working Atlas - p12

Wetlands

Page 1: Introduction

Page 2: The Coquille Subbasin

Page 3: Terrain

Page 4: Ownership

Page 5: Population

Page 6: Vegetation and Land Cover

Page 7: Geology

Page 8: Water Use and Availability

Page 9: Fish Distribution & Habitat

Page 10: Stream Temperature

Page 11: Road Density and Road and Stream Intersections

Page 12: Wetlands

Page 13: Appendix A: Tables 16 & 17

Currently, there are nearly 14,000 acres of vegetated wetlands in the lower Coquille River floodplain and over 1,500 acres of deepwater habitat. According to information derived from land surveys conducted in the late 1800s, the historic extent of vegetated wetlands in the bottomlands of the Coquille is estimated as high as 25,000 acres. The accuracy of historic area calculations, however, is limited by the nature of the inventory methodology used. The significance of change over time however, can be observed in the change in wetland type. While in the late 1800s nearly 70 percent of all wetlands were identified as timbered swamp or wooded bottom lands, approximately 90 percent of the Coquille floodplain is currently dominated by emergent grasses or upland prairies.

The National Wetlands Inventory (NWI) is a current-day inventory of wetland ecological system found throughout the United States. It was prepared by the US department of the Interior, Fish and Wildlife Service. The wetlands were identified on high altitude color infrared aerial photographs (1:58,000) based on vegetation, visible hydrography, and geography in agreement with systems defined in Classification of Wetlands and Deep-Water Habitats of the United States, by Cowardin et al 1977. The NWI identifies five different ecological systems which contain multiple and varying coding for subsystems, class, subclass and modifiers including water regimes, water chemistry, soils and special modifiers.

Historic wetlands were mapped by Patricia Benner, interpreting land survey notes from 1857–1872. These data were collected along public land survey section lines interpolating data in-between. The map was digitized by Interrain Pacific into an Arc/Info database using the public land survey section corners as control points. The resulting coverage was then attributed using base map and items added to identify symbolic relations to NWI data layer. The source date of NWI aerial photo acquisition for the Coquille data was August and September of 1982. Scale = 1:58,000.

Table 15a: Historic Wetland Classes and Corresponding National Wetland Inventory Classes
Historic Wetlands Class NWI Class 
Marsh prairie E2EMP
Timbered swamp with a brushy understory PFO/SSC (SSC/PFO)
Timbered swamp with coarse grass understory; Brush; wet and miry, muck soil and large number of beaver.  PFOC
Timbered swamp with coarse grass understory; Substantial standing water and ponds Brush; wet and miry, muck soil and large number of beaver.  PFOB
Wooded bottom land, mostly floodplain. PFOA
Upland forest U
Upland prairie PEMA
Sandy barrens with scattering of Pine PFOR 
Marshy thicket PSSR
Flat, tidal land EAB*
Pine opening U
Good grassland. E2EMN
Sources: Patricia Benner ; National Wetlands Inventory.  

These two sources of data were compared to assess the extent and nature of changes in wetland habitat in the lower Coquille since the late 1800s. Since the historic and current wetland data were developed using two different methodologies, source scales, and classification systems only a general comparison is possible. The historic wetland classes were matched as best as possible to NWI classes. In many cases the NWI classification had to be generalized.

The historic classes were matched as appropriately as possible to NWI classes as follows (numbers correspond to equivalent classes). Table 15a shows the historic wetland classes and the corresponding NWI classes. Sandy barrens with scattering of Pine, Pine opening and Upland forest were omitted from the classification as they were not relevant in relation to the floodplain.

Wetland change analysis

The NWI data was "clipped" to the extent of the original wetland data to facilitate direct overlay and subsequent area calculations. Once the two data sets were standardized overlay processes could be utilized for analytical purposes. Each data set was rasterized (Arc/Info Grid) and each cell (10 meters) was assigned its respective value (according to NWI code). A Boolean calculation was carried out to determine areas of change. Since the data sets are not directly comparable, the reliability of the results is limited.

Due to the complications in comparison, a spatial display of the overlay is not appropriate. The "two panel map" was developed as an aid to understand the nature and extent of the change that has occurred. The generalized categories are not accurate enough to depict an exact account of change.

Coquille River wetlands
[click on map for larger version]

National wetlands inventory codes

The NWI codes found in the attribute table of this database are a concatenation of coding for ecological systems, subsystems, class, subclass, and modifying terms for water regime, chemistry and soil. For example, marine, subtotal, open water body would be coded M1OW whereas a marshy area of persistent emergent vegetation would be coded PEM1.

 

Ecological systems (M, E, R, L, P)

M = Marine systems The marine system consists of the open ocean overlying the continental shelf and its associated high-energy coastline. Marine habitats are exposed to the waves and currents of the open ocean and the water regimes are determined primarily by the ebb and flow of oceanic tides.

E = Estuarine systems The estuarine system consists of deep water tidal habitats and adjacent tidal wetlands that are semi-enclosed by lands but have open, partially obstructed, or sporadic access to the open ocean, and in which open water is at least occasionally diluted by freshwater runoff from the land.

R = Riverine systems The riverine system includes all wetlands and deep water habitats contained within a channel, with two exceptions: (1)wetlands dominated by trees, shrubs persistent emergents, emergent mosses, or lichens, and (2) habitats with water containing ocean-derived salts in excess of .5 parts per thousand.

L = Lacustrine systems The lacustrine system includes wetlands and deep water habitats with all of the following characteristics:(1)situated in a topographic depression or a dammed river channel: (2) lacking trees, shrubs, persistent emergents, emergent mosses, or lichens with greater than 30% areal coverage: and (3) total area exceeds 8 hectares (20 acres).

P = Palustrine systems The palustrine system includes all nontidal wetlands dominated by trees, shrubs, persistent emergents, emergent mosses or lichens, and all such wetlands that occur in tidal areas where salinity due to ocean-derived salts is below 0.5 parts per thousand.

 

Ecological subsystems

Marine, Riverine, Lacustrine, and Estuarine ecological systems have subsystem with varying codes while Palustrine systems do not.

 

Class and subclass

Subclass have repetitive coding according to class therefore an area of subclass 1 could be one of many types including bedrock, submergent coral etc.

 

Water regimes (wat)

 

Water chemistry

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