Unfortunately, in the past, urban development in Manchester has had serious effects on rare plant species. In 1991 and 1992, an ecological inventory of the city was conducted by the New Hampshire Natural Heritage Inventory, Department of Resources and Economic Development, under the auspices of the Nature Conservancy.
One of the purposes of the study was to call attention to development pressures that might jeopardize many of the rare and outstanding natural features of the city.
As a basis of comparison with their 1991-2 findings, scientists involved in the Inventory referred to a compilation of historical records from the Natural Heritage database - records made possible by biological observations of numerous naturalists in the state over a period of 100 years. Their results were striking. At one time Manchester exhibited a wealth of natural community diversity and rare plants, but much of this natural habitat had been altered and destroyed by urban development. Originally, 38 native rare plant species were extant in Manchester, but only 14 of them remained!
Much of the Hackett Hill property was included in the Inventory. The swamp complex was described as "one of Manchester's most significant natural areas." While the report did not find that any species extirpation had yet occurred on the property, it noted several instances where a watchful eye would be needed to prevent such a happening.
The Inventory found that the giant rhododendron population located alongside Millstone Brook had been reduced in size by approximately 1/3 in the previous 5 years. This decrease was attributed to beaver activity. Many mature shrubs had died off from excessive flooding or beaver herbivory. The report noted that recent residential development to the north of the property had put pressure on the beavers to dam new areas.
The Inventory included the Dunbarton Road Hill, at the southern end of the Hackett Hill property which contains the large sweet goldenrod population. It was reported that this habitat, and the woods to the north, were becoming degraded by the presence of solid waste.
In
1994, a report on Atlantic white cedar wetlands in the state of New
Hampshire was prepared under the auspices of the New Hampshire
Natural Heritage Inventory and the Nature Conservancy and submitted
to the regional EPA in Boston. The Hackett Hill cedar swamp complex
(including the black gum swamps) was one of 14 swamp areas
investigated.
The report commented on the pristine character of the Hackett Hill swamps, the unusual occurrence of the giant rhododendrons as an understory below the Atlantic white cedars, and the age and size of the black gum trees. However, it also stated that the swamp complex is at risk from negative impacts of development. It noted that the recently-developed open space to the north of the property could have long-term impacts on hydrology and water quality in the natural communities and that "protection and management" of the remaining surrounding land would be necessary to insure their continued quality and integrity.
Investigators preparing this report also evaluated the upland forest near the southern part of the property, and noted that it was being degraded by the illegal dumping of solid waste and that "clean-up of trash could greatly improve the quality of natural communities here".
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