Statewide Summaries

The RRAs include 45% of the bottomland, 43% of the
nonforested wetland, and 34% of the upland forest in Illinois
while occupying less than 20% of the state's total area.

Thirty Resource Rich Areas (RRAs) (Figure 1) were identified using the methods described in Methodology. In total they cover 19.8% of the state (Table 1), encompassing seven of the state's 36 million acres. However, the actual area of biologically important natural resources is less than the total area of the RRAs. This results from the use of watersheds as the unit of analysis. In most RRAs, the existing natural resources occupy a concentrated portion of the watershed, or core area, often along riparian corridors. While nearly half the area within the RRAs is in agricultural production, less than 15% of the state's total cropland occurs in the RRAs. The RRAs include over one-third of the woodlands and nearly half the wet lands in Illinois (Table 1).

The RRAs range dramatically in size from 15,144 to 626,795 acres (Table 2). The largest RRAs are Big Rivers, the Southern Till Plain, and the Middle Il linois River. The smallest RRAsSugar River, Thorn Creek, Des Plaines River, Illinois Beach, and the DuPage Riverare found in the northern part of the state, the latter four in highly urbanized areas. RRAs are distributed throughout the state and occur generally on the main stems of the larger rivers or in the southern part of the state.

Landcover

Bottomland, nonforested wetland, and upland forest are well represented in the RRAs. The RRAs include 45.1% of the bottomland, 42.6% of the nonforested wetland, and 33.9% of the upland forest in Illinois, while occupying less than 20% of the total area in the state. Landcover classes with the lowest percentages in RRAs were cropland (14.9%), grassland (20.2%), and urban (20.6%). Within the RRAs cropland was the dominant landcover class (45.4%), followed by upland forests (19.8%) and grassland (18.3%).

Table 1. Landcover Composition for Resource Rich Areas and for Illinois. The "Forest - total" category is the combination of upland and bottomland forest classes and the "Wetlands - total" category is the total of nonforested wet land and bottomland forest.

Landcover Class	%State Acreage Included in RRAs	Composition of RRAs	Composition of Illinois	Acres in RRAs	Acres Statewide
Upland Forest (Forest - total) Bottomland Forest Nonforested Wetlands (Wetland - total) Urban and Built-Up Cropland Grassland Water	33.9 (35.8) 45.1 42.6 (44.6) 20.6 14.9 20.2 47.9	19.8 (25.7) 5.6 1.1 (6.8) 5.4 45.4 18.3 4.5	11.6 (14.0) 2.5 0.5 (3.0) 5.2 60.4 18.0 1.8	1,416,602 (1,815,373) 398,771 77,552 (476,323) 389,463 3,246,905 1,308,331 319,439	4,179,367 (5,064,576) 885,209 182,245 (1,067,454) 1,886,912 21,773,580 6,489,045 666,266
Total	19.8% of state	100.0% of sites	100.0% of state	7,157,063	36,062,624

Natural Areas Inventory, Biologically Significant Streams, and Natural Heritage Sites

The Resource Rich Areas include 76% of all Illinois Natural Areas Inventory (INAI) acreage and 55% of all INAI sites in the state. The distribution of INAI sites relative to RRAs is depicted in Figure 2. The Driftless Area and the Karst/Cave Area have the highest INAI acreages (Table 2). The greatest number of INAI sites occurs in Shawnee Hills, followed by Chain O' Lakes-Fox River, Cache River, Big Rivers, and Illinois Ozarks.

Forty-eight percent of all Biologically Significant Stream (BSS) mileage lies within RRA sites. The Shawnee Hills and Embarras River RRAs have the highest BSS mileage with 126 and 112 miles respectively (Table 2). Eight RRAs have no BSS streams. The distribution of BSS streams relative to RRAs is depicted in Figure 3.

Chain O' Lakes-Fox River ranked highest in occurrence of Heritage points with 476, followed by three RRAs in southern IllinoisCache River (298), Shawnee Hills (255), and Illinois Ozarks (227). The number reflects a combination of significant communities, endangered and threatened species loca tions, geological features, and colonial nesting bird sites (rookeries).

Table 2. Illinois Natural Areas Inventory (INAI), Biologically Significant Streams (BSS), and Natural Heritage occurrences for Resource Rich Areas.

Name of Resource Rich Area	Total acres	INAI acres	# INAI sites	BSS miles	# Heritage occurrences
Driftless Area	191,814	30,556	19	22.4	109
Sugar River	15,144	2,993	2	4.5	24
Chain O Lakes-Fox River	285,844	9,442	72	35.6	476
Illinois Beach	49,172	4,252	15	0	155
Kishwaukee River	64,386	362	3	15.0	8
Rock River	206,215	5,416	20	17.5	101
DuPage River	51,653	1,576	7	0	17
Mississippi-Lower Rock	457,449	18,590	17	44.2	74
Des Plaines River	43,470	2,115	11	0	61
Thorn Creek	20,614	927	5	0	13
Prairie Parklands	152,669	10,037	18	23.8	85
Kankakee-Iroquois	231,005	6,731	17	63.3	67
Peoria Wilds	277,847	1,859	24	0	51
Nauvoo	150,316	7,409	9	0	36
Mackinaw River	125,008	1,139	4	26.9	7
Middle Illinois River	575,515	13,474	38	0	134
Vermilion River	132,252	1,998	14	58.0	44
Big Rivers	626,795	10,514	61	28.9	150
Embarras River	447,925	5,009	15	112.5	50
Sangamon River	53,734	880	2	15.5	8
Upper Wabash River	170,654	2,212	4	76.4	8
Southern Till Plain	584,788	6,903	15	48.8	31
Karst/Cave Area	291,305	26,230	27	2.9	92
Lower Wabash River	163,894	4,639	12	75.5	34
Kaskaskia Bottoms	197,654	1,681	10	31.1	28
Middle Fork Big Muddy	114,908	388	1	0	2
Illinois Ozarks	466,755	17,010	59	33.1	227
Shawnee Hills	477,112	8,638	83	125.9	255
Cache River	443,616	18,444	63	52.8	298
Cretaceous Hills	87,928	1,940	19	14.1	74
Totals	7,157,441	223,364	*659	928.7	2,719

* Natural Areas occurring in more than one RRA are counted only once.

Natural Heritage Communities

Of the 968 significant community occurrences in Illinois, 58% are located in RRAs (Table 3). Several community types are well represented in the RRAs, particularly caves, primary types, savannas, and wetlands. The distribution of significant community types relative to the RRAs is illustrated in Figures 4­7 Figures 8­11.

Table 3. Occurrence of Significant Community Types in Resource Rich Areas and in Illinois.

Community Type	Occurrences Statewide	Occurrences in RRAs	Percent of each type included in RRAs
Forest	190	80	42.1
Floodplain Forest	62	36	58.1
Wetland	188	133	70.7
Prairie	312	147	47.1
Savanna	54	40	74.1
Cave	49	44	89.8
Lake	42	25	59.5
Primary (glade, cliff, lake shore)	71	55	77.5
Total	968	560	57.9

State and Federally Owned Land

Federal ownership is concentrated in southern Illinois where the Shawnee Na tional Forest is located (Shawnee Hills, Illinois Ozarks, Cretaceous Hills, and Cache River) and in the Driftless Area and Prairie Parklands RRAs (Table 4). State and federal lands are shown relative to the RRAs in Figure 12.

Table 4. State and Federally Owned Lands in Resource Rich Areas.

State Lands*						Federal Lands**
Name of Resource Rich Area	# of Parks	# Cons Areas	# of Forests	# of FWA	State acres	% of RRA	Federal acres	% of RRA
Driftless Area	1	0	0	1	3,354	1.7	40,6122	1.2
Sugar River	0	0	0	0	0	0.0	0	0.0
Chain O Lakes-Fox River	2	0	0	0	5,338	1.9	0	0.0
Illinois Beach	1	0	0	0	3,092	6.3	726	1.5
Kishwaukee River	0	0	0	0	0	0.0	0	0.0
Rock River	3	0	1	0	4,706	2.3	0	0.0
DuPage River	0	0	0	0	0	0.0	0	0.0
Mississippi-Lower Rock	2	0	0	1	1,493	0.3	15,694	3.4
Des Plaines River	0	0	0	0	0	0.0	0	0.0
Thorn Creek	0	0	0	0	0	0.0	0	0.0
Prairie Parklands	2	1	0	0	7,324	4.8	26,904	17.6
Kankakee-Iroquois	1	1	0	0	6,415	2.8	0	0.0
Peoria Wilds	0	4	0	1	9,570	3.4	1,589	0.6
Nauvoo	1	0	0	0	140	0.1	0	0.0
Mackinaw River	0	0	0	1	1,397	1.1	0	0.0
Middle Illinois River	1	5	1	2	31,630	5.5	21,499	3.7
Vermilion River	1	0	0	1	5,944	4.5	0	0.0
Big Rivers	1	1	0	0	9,547	1.5	37,901	6.0
Embarras River	3	0	0	3,226	0.7	0	0.0	1
Sangamon River	0	0	0	0	0	0.0	0	0.0
Driftless Area	1	0	0	1	3,354	1.7	40,6122	1.2
Upper Wabash River	1	0	0	0	3	0.0	0	0.0
Southern Till Plain	0	0	0	1	554	0.1	682	0.1
Karst/Cave Area	1	0	0	1	3,364	1.2	0	0.0
Lower Wabash River	1	1	0	0	1,261	0.8	0	0.0
Kaskaskia Bottoms	1	0	0	1	6,916	3.5	494	0.2
Middle Fork Big Muddy	0	0	0	1	22	0.0	0	0.0
Illinois Ozarks	1	1	1	1	18,668	4.0	81,266	17.4
Shawnee Hills	2	1	0	0	2,060	0.4	136,817	28.7
Cache River	3	2	0	0	11,924	2.7	53,741	12.1
Cretaceous Hills	1	0	0	0	619	0.7	11,999	13.6
Totals	30	17	3	12	138,567	0.6	429,924	6.0

* Parks, Cons Areas (Conservation Areas), Forests, and FWA (Fish and Wildlife Area) refer to state lands.
** Federal Land figures for Shawnee National Forest are based on ownership boundaries rather than the more general proclamation boundary.

Natural Divisions

All 14 natural divisions are represented in the thirty RRAs. The Coastal Plain, Shawnee Hills, and Lower Mississippi Bottomlands divisions are par ticularly well represented (Table 5). The Western Forest-Prairie and Grand Prairie are the least represented; these divisions have been extensively converted from presettlement conditions to agricultural use (Schwegman, et al. 1973). Figure 13 illustrates the relationship of nat ural divisions to the RRAs. Many RRAs are comprised of a single natural division, such as Chain O' Lakes-Fox River, Kishwaukee River, DuPage River, Thorn Creek, Kankakee-Iroquois, Mackinaw River, Sangamon River, Kaskaskia Bottoms, and the Middle Fork of the Muddy River. Others are composites of several divi sions, particularly the Mississippi-Lower Rock and Big Rivers RRAs.

Table 5. Natural Divisions in Illinois and in Resource Rich Areas. Natu ral divisions are listed from lowest to highest area in Illinois.

Name of Natural Division	Percent of Illinois	Percent of Division Contained in RRAs
Wisconsin Driftless	1.0	37.3
Lower Mississippi Bottomlands	1.0	79.7
Illinois and Mississippi River Sand Areas	1.1	61.4
Ozarks	1.1	63.7
Coastal Plain	1.3	85.2
Shawnee Hills	2.5	81.6
Upper Mississippi and Illinois River Bottomland	3.3	64.5
Rock River Hill Country	4.2	14.8
Middle Mississippi Border	4.3	35.6
Wabash Border	4.8	34.0
Northeastern Morainal	6.8	22.6
Western Forest-Prairie	12.2	4.4
Southern Till Plain	19.8	15.2
Grand Prairie	36.1	8.6

Return to Table of Contents