. Critical trends in Illinois ecosystems. Ecological assessment (Biology); Environmental impact analysis; Nature; Pollution; Conservation of natural resources; Environmental quality. Ecosystem Monitoring Results 19 liighly sensitive to fragmentation; an average of onh' of these species were found per site. Although historical data are lacking on the diversit)' and abundance of these 10 species, the average of less than one species per site clearly reflects the degraded condition of the average forest patch in Illinois. Partially due to their mobility' and the mobilirj' of their predators,
. Critical trends in Illinois ecosystems. Ecological assessment (Biology); Environmental impact analysis; Nature; Pollution; Conservation of natural resources; Environmental quality. Ecosystem Monitoring Results 19 liighly sensitive to fragmentation; an average of onh' of these species were found per site. Although historical data are lacking on the diversit)' and abundance of these 10 species, the average of less than one species per site clearly reflects the degraded condition of the average forest patch in Illinois. Partially due to their mobility' and the mobilirj' of their predators, birds can respond to disturbance at a regional scale as well as at the local sites where they breed. Because of this, it is useful to monitor bird populations in relation to landscape habitat characteristics. Figure 12 shows that when forest is less abundant at the regional level, bird diversity' at randomly selected forest patches is lower than in areas where forest is more widely distributed. Fragmentation can compound problems caused by the loss of habitat because more fragmentation means more edge habitat. These edges often harbor species that prey on bird nests. Moreover, brown- headed cowbirds, which parasitize the nests of mam' birds, thrive in open landscapes that have both open habitat for feeding and woodland where they lay their eggs in host nests. Cowbirds were detected from within 84% of the forest patches — a higher detection rate than any of the area sensitive forest species. Because one female cowbird is capable of laying up to 40 or more eggs per year, these figures highlight the impact that cowbirds can have on the reproductive success of forest bird populations in the average forest site. GRASSLANDS Prairies once covered 61% of the Illinois landscape. (Airrentiy only about 2,300 acres of high qualit\' prairie remain, which is about of the presettlement acreage. Although most native prairies have been eliminated, 6,,409 acres ( of the state)
Size: 1359px × 1839px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorillinoisnaturalhistorysurveydivisi, booksubjectnature
