Old Fields & Disturbed Land
The purist would probably include 90% of Cedar Creek in the disturbed category. The cynic would probably say ‘show me something undisturbed’. Very little of the Area has escaped the hand of man. Considerable areas of upland were cleared for agriculture. Most of the upland woods were pastured or logged. Part of the creek and some wetlands were dredged. Natural fires were suppressed. Although most of these practices have been discontinued, their effects are still visible. An obvious one is the rectangular margins of our abandoned fields. A less obvious example of past disturbance still visible today is Juniper Savanna. This tract of beautiful open-grown bur oaks was heavily grazed by cattle until the early 1970s. The cattle ate everything except the unpalatable bush juniper (Juniperus communis) which eventually came to dominate the understory to the exclusion of all else. This juniper savanna may be interesting to look at, but it is still not well.
Among the more obvious signs of disturbance are fields abandoned from agricultural use, pine plantations, roadsides, ditches, canary grass wetlands, gardens and homesites, and experimental plots. Of 113 species of introduced plants found on the area, fully 90% occur primarily/solely on such disturbed land.
Cedar Creek contains more than 100 fields that have been abandoned from agriculture. These range in age of abandonment from 1927 to the present. (Perimeter fields that are now farmed are periodically released from cultivation so that a chronosequence of abandoned land will always be available for study.) A few of the oldest fields have reverted to sand prairie. These occur in some of the Burn Units in the southern half of Cedar Creek and are discussed in the section on Sand Prairie and Savanna. Several fields were planted in the European perennial Bromus inermis (Smooth Brome) in the 1950s and are still dominated by this grass. Examples include: HUT, RSW, PMN… Abandoned fields not included in the Cedar Creek Burn Program occur primarily in North Section. Poa pratensis, Agropyron repens, Setaria glauca, and Carex foenea are the four dominant graminoids of most of these fields. A few of the fields in North Section that were abandoned in the 1950s are now dominated by Schizachyrium scoparium (Little Bluestem). Although woody invasion of abandoned fields at Cedar Creek is extremely slow, several of these ‘schiz fields’ have been invaded by White Pine from surrounding upland forests. Examples include: B, BGS, LBS… Pocket gopher mounds andbadger diggings are a common sight in Cedar Creek old fields.
Fields last cultivated in the 1970s or more recently retain a weedy character. Poa pratensis (Kentucky Bluegrass), Agropyron repens (Quackgrass), Setaria glauca (Yellow Foxtail), Digitaria ischaemum(Crab Grass), Agrostis alba (Redtop) are five common completely naturalized exotic grasses. Common weedy forbs, many of them introduced species, include: Ambrosia artemisiifolia (Ragweed),Polygonum convolvulus (Bindweed), Conyza canadensis (Horseweed), Verbascum thapsus (Mullein),Berteroa incana (Hoary Allysum), Lepidium densiflorum (Peppergrass), and Chenopodium spp (Lamb’s Quarters). A more complete listing is provided in the accompanying Table.
Several Pinus strobus and P. resinosa (White and Red Pine) plantations were established in the 1950s. Most occur near residences (South House Pines, Bur Oak Pines, Beckman Lake Pines, Lundgren Pines). These were planted rather densely, have an acidic needle duff, and very little in the way of a ground flora. Pinus sylvestris (Scotch Pine) is a common windbreak tree planted along roadsides and betweenfields.
Homesites & Gardens
Conspicuous elements here are tree plantings, ornamentals, and garden plants. Most rarely escape the homesite. Two species of trees that are exceptions are Ulmus pumila (Siberian Elm) and Robinia pseudoacacia (Black Locust). Siberian Elm has invaded the succession strips and is found in LCfield. Black Locust has invaded fields and woods off the SE corner of Fish Lake. Robinia hispida (Prickly Locust) is found near the old Lundgren homesite, Caragana arborescens (Siberian Pea) is found near Corneia’s Cabin, Spiraea van-houttei is found at the Heckenlaible homesite, Syringa vulgaris (Lilac) is found at several homesites, and Sorbaria sorbifolia (False Spiraea) occurs near the Lab. Other woody species restricted to homesites include: Picea abies, Picea pungens, Picea glauca, Acer saccharinum…Common ornamental forbs confined to homesites include Hemerocallis fulva (Day Lily), Convallaria majalis (Lily of the Valley)…
Roadsides & Ditches
The mowing of roadsides has enabled several species of roadside weeds to become established. Included in this group are: Circium arvense (Canada Thistle), Sonchus arvensis (Sowthistle), Medicago sativa (Alfalfa), Melilotus spp (Sweetclovers), Trifolium arvense (Rabbitfoot Clover)…
Reed Canary-grass Wetlands
This is an unnatural community created by draining other wetlands and seeding them with the exotic and now fully naturalized Phalaris arundinacea (Reed Canary Grass). These were mowed for meadow hay following the drought years of the 1930s, but are generally now ignored as forage or even pasturage. Enormous tracts occur throughout the Anoka Sandplain, especially on Carlos Avery WMA. Fortunately, Cedar Creek has very little of this community type. The largest ‘unnamed’ example lies off the southeast shore of Fish Lake.
When Cedar Creek became a Long Term Ecological Research (LTER) site in 1982, portions of several of the Area’s old fields were ‘Zoned’ for experimental work. (See GIS and Experiments for exact locations.) Major Disturbance Areas have been confined to fields A, B, C, D, and E. Much of this work has examined the effect of N-fertilization or disturbance (eg. burning, roto-tilling) on old field communities. Macroplots (measuring 20x50 meters) were established in 1982 in fields A, B,C, D and fertilized at varying intensities until 19xx. Fenced areas containing numberous fertilized microplots(4x4 meters) were established in these same fields in 1982 and continue to be maintained. A set ofHerbivore Exclosures were set up along the perimeter of BLN in 19xx. Solidago Transplant Gardens have been established in A, B, BP and BDG. Functional Group Gardens were established by Amy Symstad in field C. Experimental Gardens were created in BP, BDG, BioCON and these have drastically altered the appearance of these areas. The topsoil was removed by earth-moving equipment to reduce soil-banked seeds before the experimental gardens were established. The seeds used in these gardens were purchased from commercial sources rather than being harvested locally. Species selected for these experiments have generally been native to the Area, but exceptions have occurred. Most notable are Bouteloua gracilis, Buchloe dactyloides, Monarda punctata… The seeds of ca. 30 prairie species were added to plots in Field D in 1988 artificially increasing the diversity of this savanna. Several of the species added (eg. Baptisia, Lupinus, Zizia) did not occur there previously.
Work confined to Minor Disturbance Areas is anticipated to have only minimal long-term impact. Such work would include erecting small temporary exclosures, marking plants, etc. Most areas on Cedar Creek Ecosystem Science Reserve are available for this sort of study. (See Research Protocol)