Giant Hogweed Distribution - County Level Map

Written by charlie   
Friday, 24 July 2015 17:41
In a followup to my last post, here is a county level map of where Giant Hogweed has been found nationwide. The map is courtesy of EDDMapS, and the Center for Invasive Species and Ecosystem Health at the University of Georgia.

Giant Hogweed

Written by charlie   
Wednesday, 22 July 2015 00:09
Summer, this wonderful season of swimming, picnics, BBQ, mosquitos, posion ivy, and...Giant Hogweed? Seemingly straight out of the Jurassic age, the Giant Hogweed (Heracleum mantegazzianum) is not lightly named, living up to 25 years, with stalks reaching 15 feet tall and leaves up to 5 feet long. The plant is reminiscent of the familiar Queens Anne's lace (Daucus carota), which also falls into the carrot family (!) and whose sap has similar irritative properties. Giant Hogweed is considered a facilitative wetland plant, occurring both in wetlands and non-wetlands, generally along river beds, forest edges and other disturbed or border areas.

Beyond its impressive size, Giant Hogweed is notorious for its sap effects on skin - worse and longer lasting than than poison ivy. The sap sensitizes skin to the suns UV rays within 15 minutes, causing blisters to form within 24-72 hours, which can leave scars behind lasting months to years. The affected areas often remain sensitive to UV light, potentially leading to a recurrence of blisters years later. Even worse, if the sap if gotten in the eye, it can cause blindness.

The N.Y. Department of Health recommends that if the sap contacts skin, it be washed off with cold water immediately and either apply sunscreen or cover up the affected areas since this can prevent further reactions. The toxic reaction can begin as soon as 15 minutes after contact. If Hogweed sap gets into the eye, rinse with cold water immediately and put on sunglasses.

Giant Hogweed also is considered invasive, and quickly crowds out native species in areas it colonizes. In a dominant stand, up to 80% of incoming light is absorbed by its large leaves and flowers, shading out any species which fall under its canopy.

According to the NY DEC, the plant grows in New York, Pennsylvania, Connecticut, Ohio, Maryland, Oregon, Washington, Michigan, Virginia, Vermont, New Hampshire and Maine.

Hogweed control is difficult; it produces a prodigal amount of seeds, between 20,000 to 100,000 per year, which can remain viable for upto 7 years in the soil. Additionally, its large root can survive multiple cuttings. Control using multiple applications of herbicide over a few growing seasons is most successful. Additional info here:

Giant Hogweed in CT

Giant Hogweed Control

Hogweed Control

The Giant Hogweed Best Practice Manual, (available in multiple languages):

Last Updated on Wednesday, 22 July 2015 00:25

Historic USGS Maps

Written by charlie   
Monday, 20 July 2015 00:20
In May, the US Geological Survey (USGS) released a new tool "Topoview" making it easier to access its trove of almost 180,000 historical maps, many of which previously been only available for internal USGS use.These maps date from the mid 1800's through the 1980's nationwide.

Maps many decades outdated are often still relevant, serving as a historical record and source document for tracking changing geographical data. With the emphasis on climate change and sea level rise, old maps are especially good at showing the shifting borders of wetlands, coastal areas, and changes in land use over time.

Most often the largest hurdle in making a historical map useful to a larger population is the scanning and warping, or georectification process. Scanning, while time consuming and requires great care, is but just the first step for accurately comparing old and new maps. A scanned map can be used for visual comparison, but georectification, the process of warping and digitally assigning coordinates to a scanned map, becomes important if a historical map is needed for any GIS analysis or use along side a Googlemap to accurately compare former and current conditions.

Check out the USGS Topoview Mapping Tool here and use them for your own projects!

 1905 Outline map of New York Harbor & vicinity : showing main tidal flow, sewer outlets, shellfish beds & analysis points.
Last Updated on Tuesday, 21 July 2015 02:27
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