(above) Current year accumulated GDD anomaly, 50F base
temp, May 10, 2016.
(bottom left) Current-day temperature accumulation, 50F
base temp, May 10, 2016.
Daily maps of accumulated GDDs as well as temperature anoma-
ly maps, which communicate how heat accumulation in the year
of interest compares to long-term average conditions, can be
readily viewed through the USA-NPN's
online visualization tool.
Using daily accumulated GDD maps, it is possible to evaluate
where particular thresholds have been met on a particular
date as well as to estimate when a threshold will be met at a
particular location, which can enhance planning management
actions. For example, pesticides for emerald ash borer (Agrilus
planipennis) are most effective at controlling these insects
when they are applied after adults emerge and before they
start to lay eggs. According to Dan Herms and colleagues at
OSU, adults begin to emerge around 450-550 GDDs and are
most abundant around 1,000 GDDs based on a Jan 1 start date
and a 50F base temperature. Adults lay eggs approximately 14
days after emergence, so treatment is critical in the two-week
window following emergence. By tracking GDD accumulation at
a particular site over the course of the spring, it is possible to
pinpoint the two-week window during which pesticide applica-
tion would be most effective.
The USA-NPN visualization tool provides a user-friendly display
of the management window across space, as shown in the fig-
ures on pages 14 and 15. The panel on the left shows tempera-
ture accumulation for the U.S. as of Jun 15, 2017. The panel on
the right shows locations that had accumulated between 500
and 1,000 GDDs as of this date and where emerald ash borer
pesticide treatment would be appropriate. Locations to the
north of the green band, such as the site selected by the pin,
had not yet reached 450 GDDs as of Jun 15.
What is the USA National Phenology Network?
Funded primarily by the U.S. Geological Survey, the USA
National Phenology Network is a national-scale consortium
of individuals and organizations that collects, stores, and
shares phenological data, value-added data products, and
information to advance science and to support natural
resource decision-making across a variety of spatial and
temporal scales. The Network delivers free and readily
available phenological data, connects researchers studying
how species respond to climate change with managers who
need this information to inform adaptive management, and
creates a diverse community of stakeholders. The USA-NPN
also hosts Nature's Notebook, a plant and animal phe-
nology observation program suitable for natural resource
managers as well as nature enthusiasts of nearly all ages
and skill levels.
www.usanpn.org
www.urban-forestry.com 13 www.urban-forestry.com 13
