Symphyotrichum dumosum (L.) G. L. Nesom




Дата канвертавання18.04.2016
Памер16.05 Kb.

Symphyotrichum dumosum (L.) G.L.Nesom
















Current Status

TU

Proposed by: Sara Helm, Ann Rhoads, and Tim Block

Proposed Status (click for definitions)

PE

Morris Arboretum/Academy of Natural Sciences










Estimated number of extant occurrences

(4) 4 – 7 (8)






















Estimated number of extant individuals

(1500) 2000 – 3000 (3000) Ramets










Factors that increase conservation concern






















»In several places where the plant was previously known to exist, there are now invasive species monocultures. Also, fires which were common in the habitat are now suppressed.
















»Much habitat has been lost due to human construction of buildings, parking lots, etc.




»Yes. The occurrences in Erie, PA are quite far from any other PA, NY, and OH occurrences.




»In the past 100 years, S. dumosum has seen a greater than 80% reduction in known occurrences. In the past 20 years, it has seen a decline from six known occurrences to four known occurrences, and a large reduction in population size for at least one site. Fire suppression, invasive species encroachment, deer browsing, forest succession, and the construction of buildings, roads, etc. have contributed to this reduction.




»One site is protected through an easement, but the owner does not manage the site for the preservation of species such as S. dumosum. Two of the other sites are also not managed for preservation of S. dumosum.




»For example, Nottingham County Park in Lancaster County was known as recently as 2005 to have occurrences of S. dumosum. When surveyed in September and again in October of 2008, no S. dumosum was found. A large population of Microstegium vimineum covered the entire area where S. dumosum was previously known to exist. From this example and several others, it can be concluded that the viability of S. dumosum in several of the places where it currently occurs may be questionable.




Factors that decrease conservation concern






















»Historically, the areas where the plant grew were thin soils with high heavy metals and low nutrients, rocky substrates with high pH; both conditions undesirable for farming. Recently, however, people have built homes and buildings on this type of land. The anthropogenic disturbance that this plant tolerates is controlled burning.




»Since natural fires are suppressed, the species can benefit from controlled burning of its habitat.




»The white form of Symphyotrichum dumosum looks like several other Symphyotrichum species; especially S. lateriflorum, with which it frequently grows.




»S. dumosum is only identifiable when it is flowering (usually in October and November until the first frost). For this reason, and the fact that it resembles other Symphyotrichum species, botanists may not see it, as most surveying occurs during the spring and summer to early fall.




»One site is managed to preserve the species diversity and unique ecology there, allowing S. dumosum to thrive in its preferred habitat.





























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