The Ecology of a City Park Frick Park, Pittsburgh, PA. By William LeRoy Black, M.S. University of Pittsburgh Images from the report    Description of the Area   Frick Park, an area of some four hundred and seventy-six acres, consists of three wooded, modified ravines, lowland and upland feilds in varying stages of scrub and second growth. It represents an area approaching climax conditions, but the destruction brought about by man maintains this area in a disclimax condition. The park is surrounded by houses and industrial installations, except for the west boundry just accross Commercial Street where the valley has been practically filled with slag by Duquesne Slag Products Company. Frick Park is an oasis within a city. Nine Mile Run Hollow is the largest and oldest of the three ravines. Nine Mile Run emerges from a storm and sewage sewer under Braddock Avenue. It carries sewage and industrial waste, and recieves further pollution from breaks in the sewers crossing the run. There are no continuously flowing unpolluted streams in this hollow. Most of the land bordering the creek has been leveled and seeded with grass. Trees have been planted in open fields, and shrubbery has been introduced in mass plantings around the parking lot, and along the trails. Two large clearings have been reserved for playing fields. The over grown field below the parking lot was plowed over during World War II for Victory Gardens, which were abandoned in 1945. The original polluted Fern Hollw Creek has been contained in a sewer running the entire length of Fern Hollow, emptying into the large concrete sewer in Nine Mile Run Hollow. The present creek is the overflow from the lily pool in the Homewood Cemetary. Frick Park lies in a pre-glacial river channel or loop which extends north from the Monongahela valley in Oakland near the Cathedral of Learning. The underlying rocks belong to the Conemaugh Fromation, about three hundred feet above the Freeport Coal. At the river level lies the Pittsburgh Red Beds which outcrop in Nine Mile Run and Fern Hollow. No coal viens apear in the park, although the Pittsburgh Coal outcrops on the higher points in Squirrel Hill. Clay, shale, and sandstone lie immediatly below the sod in most of the grassy areas. The changes made by man in Frick Park have been very extensive. Except for the construction completed before the area became a city park, these activities were undertaken with the maintenance of a natural area in view. Methods of Observing and Collection   The area was studied from July 1946, to July 1947, recording the native and introduced flowering plants. Mosses, lichens, fungi, and the presence of galls were also recorded. Birds were observed and recorded during thier fall and spring migrations. Permanent residents, winter visitors, casuas, gypsies, and nests were likewise recorded. Sight records, tracks, owl pellets and traps were employed to estimate the mammal population. There are no fish in any of the streams or ponds in Frick Park. Description of the Alterations by Man Storm and sewage lines from [the surrounding] communities empty their contents into Nine Mile Run. To contain this sewage, more sewers were built. These sewers followed the stream channels, altering the creek beds and the entire drainage system. A further decrease in the amount and type of water available to the plants and animals was caused by the blasting in the stream channels for the sewers. Seepage lowered the actual height of the water to beneath sewer level, out of the reach of many plants and animals. The construction of tile drainage sewers on Beechwood Boulevard, Forbes Street, Braddock Avenue, and the connecting streets, contained the springs and streams, and prevented the filtering of the water into the ravines, further lowering the water table. The construction of trails further altered the drainage system by filling, grading and draining pools and swampy areas. The drainage ditches are open sewers carrying rain water away before it can soak into the ground. The trails increase destructive traffic--both human and animal. This results in erosion along the trails and in the increased evaporation of moisture. For many years the trees and shrubs were heavily pruned in Frick Park, especially in those areas frequented by the public. Standing and fallen dead timber was removed to supply firewood, to eliminate fire hazards, and to improve growth. Many species of plants have been introduced into the creek areas, hillsides and hilltops, especially along the trails, around the parking lots, bowling greens, playgrounds, tennis courts, and the entrances. Preference was given to those plants available that would grow in the city. Many plantings were experimental, and not too much thought was given to those plants that supply food for animal life. As a result, most of the plants were not native to this area, and replaced the original natural plantings. The plant and animal populations, native and introduced, have been protected by laws against willful picking or destruction by the public. Some native plants and animals have been re-introduced into the park by pak personnel and interested visitors. Results of Random Construction Activities on Plant Life Construction of Sewers and the Alteration of the drainage system. The open sewage flowing into the streams had already destroyed the water loving plants long before the improvements had occured. Filling in the old creek beds, pools, and marshy depressions has eliminated many more plants. The shallow stream channels soon choke up with debris and overflow easily, depositing thier load on the surrounding vegitation. During heavy rains these streams erode the soil away from the roots of trees and shrubs, cut new channels in the denuded creek bottoms, and wash out many flowering plants. The dirt and debris covering the roots of the trees and shrubs often results in the death of these plants. The chemical and sewage polution flowing into Nine Mile Run after these "improvements" still prevents the growth of any vegetation in the water, or surroundijng stones and logs. The water rushing from the storm sewer under Braddock Avenue after heavy rains produces unbelievable destruction, washing out trails, bridges, retaining walls, and any flowering plants in the path of the raging torrent. Trees and shrub are carried like battering rams down the swollen run, gouging out sections of the bank and any other plants in their path.