Spatio-temporal drought trends by forest type in the conterminous United States, 1960-2013

2014·0.33 MB·English

by  Peters, Matthew P

Historic, Archive Document
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US DA
United States Department of Agriculture
Spatio-temporal Drought Trends by
Forest Type in the Conterminous
United States, 1960-2013
a63701
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Matthew P. Peters, Louis R. Iverson, and Stephen N. Matthews 2014
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Map Description
Droughts are common in virtually all U.S. forests, but their frequency and intensity vary within forest ecosystems (Hanson and
Weltzin 2000). Accounting for the long-term influence of droughts within a region is difficult due to variations in the spatial extent
and intensities over a period. Therefore, we created a cumulative drought severity index (CDSI) (Fig. 1) for the United States
using weighted monthly frequencies of Palmer Drought Severity Index values reported at climate divisions for the periods 1960
to 1986 and 1987 to 2013 (National Climate Data Center 2014, Palmer 1965). The occurrences of‘severe' conditions (index
value of -3.0 to -3.9) receive a weight of 2 and ‘extreme’ (index value of < -4.0) receive a weight of 3 to reflect the increased
magnitude of these events.
The Authors
Matthew P. Peters is a forestry technician and Louis R. Iverson is a research landscape ecologist with the Northern Research
Station in Delaware, OH. Stephen N. Matthews is a research assistant professor in the School of Environment and Natural
Resources at Ohio State University and is affiliated with U.S. Forest Service at the Northern Research Station.
Forest Service Northern Research Map Publication Date
Research Station NRS-7 December 2014

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USDA
United States Department of Agriculture
Spatio-temporal Drought Trends by Forest Type in the Conterminous United States, 1960-2013
Matthew P. Peters, Louis R. Iverson, and Stephen N. Matthews
1960-1986 1987-2013
NhtotprtJh/ wAwmwe rnicoadne Onoroauag ghol vM/toenmitpo-r aInndd-ipcreesd p/drought/nadmimdices php7
U S Forest Service and U S Geological Survey 2000 Forest Cover Types
httpy/wvwr fia.fs.fod.us/libraryf maps/
Map Description
(DHraonusgohnts a anrde Wcoemltmzino n2 0in0 0v)i.r tAuaclcloyu anllt inUg.S f.o fro trhees tlso, nbgu-tt etrhmei ri nffrleuqeunecnec yo fa dnrdo uingthetnss iwtyi thvianr ya wreitghioinn fiosr desiftf eiccuolsty dsuteem tos Flaonrde satn cdo svuemr tmypaerisz dee wfieniegdh bteyd t hfree qUu.Sen. cFioerse ostf Sdreorvuigchet ioncccluudrrei n2g1 dduisrtiinngc et agcrohu 3p2s4 t-hmato wntehr ep eursieodd .t oA mddaistkio nnoanllfyo, rfeosrteesdt TOarbolueg 1h.l sP reerpcoerntte do fa dt rdoiumgahlto o dcicvuirsrieonncs ec oanmtaoinngin mg ae)aocrh f ofroersets tt ytyppees owfe trheo u csoendte trom aigngoruesg Ualnoi tveadl uSetas laens da ncdal rceullaattiev ep ceurcmeunltaatgivees dorfo tuhgeh 3t 2s4e-vmenotnyt hin pdeerxio (dC OSI): DPaaltma eSro Durrocuegs ht Severity Index values were obtained from the National Climatic Data Center (2014) and used
variations in the spatial extent and intensities over a period. Therefore, we created a cumulative drought severity cover types were combined within eastern and western United States and drought frequencies among climate 1960-1986 1987-2013 to calculate the CDSI. The forest cover types layer was provided by the U.S. Forest Service and U.S. Geological
index (CDSI) (Fig. I) for the United States using weighted monthly Irequencies of Palmer Drought Severity Index divisions were summarized for the two periods (Figure 2). Survey (2000) and used to mask nonforested land.
values reported at climate divisions for the periods I960 to 1986 and 1987 to 2013 (National Climate Data Center
2014. Palmer 1965). The occurrences of‘severe-conditions (index value of-3.0 to -3.9) receive a weight of 2 and Drought severity has increased throughout the West, Southeast, and Lake States (see map at right). The Northeast Suggested Citation
•extreme- (index value of <-4.0) receive a weight of 3 to reflect the increased magnitude of these events. and Mid-Atlantic States have not experienced such severe droughts in the latter period. The mapped areas show Peters, Matthew P.; Iverson. Louis R.: Matthews. Stephen N. 2014. Spatio-temporal trends of drought by forest
that the frequencies of drought conditions in forests have significantly increased in the West compared to the East. type in the conterminous United States. 1960-2013. Res. Map NRS-7. Newtown Square. PA: U.S. Department
1960-1986 1987-2013 Dadrjouusgtehdt fforer qthuee nncuimesb efor rm foonrethstse pde rla cnldim oaft eth dei vciosinotne.r mFoinr oeuacs hU fnoirteesdt tSytpaet,e sd rdouurginhtg c tohned ipteiorinosd w 1e9re6 0s-u2m01m3a rwizeerde of Agriculture. Forest Service, Northern Research Station, [scale 1:12,000,000).
as the percentage of months during the 324-month period (27 years) among climate divisions that contained the Literature Cited
forested land (Table I). Data used to create these maps can be obtained by contacting the author: matthewpeters@ Hanson. P.J.; Weltzin, J.F. 2000. Drought disturbance from climate change: response of United States forests.
fs.fed.us. Science of the Total Environment. 262(3): 205-220.
National Climatic Data Center. 2014. North American drought monitor indices. Asheville, NC: U.S. Department
of Commemce, National Oceanic and Atmospheric Administration, National Climate Data Center. Available at
www.ncdc.noaa.gov'temp-and-precip/drought/nadm/indices.php? (Accessed July 22.2014).
Palmer. W.C. 1965. Meteorological drought. Washington, DC: U.S. Department of Commerce. 58 p.
U.S. Forest Service and U.S. Geological Survey. 2000. Forest cover types. Washington, DC: U.S. Department
of Agriculture. Available at mvw.fia.fs.fed.us/library/maps/ (Accessed July 22. 2014).
The USDA is an equal opportunity provider and employer.
M0= modorate drought (-2.0 to -2.9), SD=sovero drought (-3.0 to -3.9). E0=cxtremo drought (s -4)
1. Cunutarr.n drought seventy index values wtueh are a
a-ous Unted Slates for (he periods 1960101986 and 19S
depdrng the mpaa of droughts wthm forests (largo map and in:
2. Comparison of Pa
among ooslom and
Forest Service NReosrtehaerrcnh Station Research Map DPuebcleicmabtieorn 2O01al4e xtnod 1960-2013
Manuscript received for publication Map Disclaimer
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