Forest Surveys: Comparing Efficiency and Accuracy of ... › files › 2016_McGarigal_CTS... ·...
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Forest Surveys: Comparing Efficiency and Accuracy of Digital Photography and Laser Based Techniques Introduction Methods Results Conclusion Future Research Alison McGarigal 1 , Chuck Cannon 2 Acknowledgements: We would like to thank The Center for Tree Science at The Morton Arboretum for funding this research. We would also like to give a special thanks Lane Scher, Drew Duckett, Meghan Midgley, Quin Taylor, Christine Carrier, Jessica Turner-Scoff, Catherine Bechtoldt for their help and support. 1 Alison McGarigal Colorado College, Center for Tree Science Undergraduate Research Fellow [email protected] To understand how human activity drives shifts in the composition and structure of forests, we must document our current forests as much as possible. • The traditional method of collecting this data is costly in terms of human effort and time requirements • Implementing technology could allow us to conduct forest surveys over a large area more frequently Aim: To determine if digital photography or hand-held laser technology could improve the efficiency of forest surveying while maintaining the accuracy of the traditional method. Survey study design • 30 circular plots assigned an area of 314 m 2 , 707 m 2 , or 1257 m 2 Techniques tested • Traditional tape measure method • Dual-laser method • Photography method (PhotoPoint) developed by AusPlots Rangelands at the University of Adelaide, Australia Sources: LaBau, Vernon J., James T. Bones, Neal P. Kingsley, H. Gyde Lund, and W. Brad Smith. "A History of the Forest Survey in the United States: 1830–2004.” (n.d.): n. pag. USDA. USDA Forest Service, June 2007. Web. 2 Aug. 2016. Thompson, I., B. Mackly, S. McNulty, and A. Mosseler. "Forest Resilience, Biodiversity, and Climate Change." Secretariat of the Convention on Biological Diversity, Montreal (2013): 91-104. Convention on Biological Diversity. Convention on Biological Diversity, 2009. Web. 2 Aug. 2016. Dick, Adam R., John A. Kershaw, Jr., and David A. MacLean. "Spatial Tree Mapping Using Photography." Northern Journal of Applied Forestry 27.2 (2010): 68-74. Web. 22 June 2016. Laser Method PhotoPoint Method Traditional Method Figure 1. The time it takes to complete each method Figure 2. The impact of distance on the Laser’s DBH error Figure 3. The significance of DBH of the trees missed Figure 4. The significance of the distance of trees missed Efficiency • PhotoPoint is the fastest method tested (Figure 1; p < 0.05) • When few trees are measured in small areas, all methods are similarly efficient (Figure 1; p = 0.16) • No significant difference between the time requirements for Traditional and Laser methods (Figure 1; p = 0.799) Accuracy • Error in DBH and distance estimations of the Laser increases gradually as the distance to the tree increases (Figure 2; p < 0.05) m 2 m 2 m 2 m 2 m 2 m 2 Missed Trees • Laser method misses trees that have small diameters (Figure 3; p < 0.05) and that are near the edge of plots (Figure 4; p < 0.05) • Traditional method also misses trees on the edge of plots (Figure 4; p < 0.05) but over a larger range of diameters (Figure 3) 2 Dr. Chuck Cannon Center for Tree Science at The Morton Arboretum [email protected] PhotoPoint: good alternative method for conducting forest surveys • Time required to photograph a plot is independent of the number of trees in a plot, which increases it’s efficiency • Potential for photographs to collect incidental data, such as understory thickness and composition, and tree growth forms Laser method: poor alternative for conducting forest surveys • Compared to Traditional method: equally efficient, less accurate DBH estimates, trees missed more frequently, more expensive • Synthesize data collected by the PhotoPoint method and compare the accuracy of the data to the other two methods • Optimize protocol of PhotoPoint method to gather the highest quality and quantity of data • Evaluate the potential insights the incidental data collected by the PhotoPoint method could provide Area of Plot Area of Plot
Transcript of Forest Surveys: Comparing Efficiency and Accuracy of ... › files › 2016_McGarigal_CTS... ·...
ForestSurveys:ComparingEfficiencyandAccuracyofDigitalPhotographyandLaserBasedTechniques
Introduction
Methods
Results Conclusion
FutureResearch
AlisonMcGarigal1,ChuckCannon2
Acknowledgements:WewouldliketothankTheCenterforTreeScienceatTheMortonArboretumforfundingthisresearch.WewouldalsoliketogiveaspecialthanksLaneScher,DrewDuckett,MeghanMidgley,Quin Taylor,ChristineCarrier,JessicaTurner-Scoff,CatherineBechtoldt fortheirhelpandsupport.
1AlisonMcGarigalColoradoCollege,CenterforTreeScienceUndergraduateResearchFellowali.mcgarigal@coloradocollege.edu
Tounderstandhowhumanactivitydrivesshiftsinthecompositionandstructureofforests,wemustdocumentourcurrentforestsasmuchaspossible.• Thetraditionalmethodofcollectingthisdataiscostlyintermsof
humaneffortandtimerequirements• Implementingtechnologycouldallowustoconductforest
surveysoveralargeareamorefrequently
Aim:Todetermineifdigitalphotographyorhand-heldlasertechnologycouldimprovetheefficiencyofforestsurveyingwhilemaintainingtheaccuracyofthetraditionalmethod.
Surveystudydesign• 30circularplotsassignedanareaof314m2,707m2,or1257m2
Techniquestested• Traditionaltapemeasuremethod• Dual-lasermethod• Photographymethod(PhotoPoint)developedbyAusPlots
RangelandsattheUniversityofAdelaide,Australia
Sources:LaBau,VernonJ.,JamesT.Bones,NealP.Kingsley,H.Gyde Lund,andW.BradSmith."AHistoryoftheForestSurveyintheUnitedStates:1830–2004.”(n.d.):n.pag.USDA.USDAForestService,June2007.Web.2Aug.2016.Thompson, I.,B.Mackly,S.McNulty,andA.Mosseler."ForestResilience,Biodiversity,andClimateChange."SecretariatoftheConventiononBiologicalDiversity,Montreal (2013):91-104.ConventiononBiologicalDiversity.ConventiononBiologicalDiversity,2009.Web.2Aug.2016.Dick,AdamR.,JohnA.Kershaw,Jr.,andDavidA.MacLean."SpatialTreeMappingUsingPhotography."NorthernJournalofApplied Forestry27.2(2010):68-74.Web.22June2016.
LaserMethodPhotoPointMethodTraditionalMethod
Figure1.Thetimeittakestocompleteeachmethod Figure2.TheimpactofdistanceontheLaser’sDBHerror
Figure3.ThesignificanceofDBHofthetreesmissed Figure4.Thesignificanceofthedistanceoftreesmissed
Efficiency• PhotoPointisthefastestmethodtested(Figure1;p<0.05)• Whenfewtreesaremeasuredinsmallareas,allmethodsare
similarlyefficient(Figure1;p=0.16)• Nosignificantdifferencebetweenthetimerequirementsfor
TraditionalandLasermethods(Figure1;p=0.799)
Accuracy• ErrorinDBHanddistanceestimationsoftheLaserincreases
graduallyasthedistancetothetreeincreases(Figure2;p<0.05)
m2m2m2 m2 m2 m2
MissedTrees• Lasermethodmissestreesthathavesmalldiameters (Figure3;p<
0.05)andthatareneartheedgeofplots(Figure4;p<0.05)• Traditionalmethodalsomissestreesontheedgeofplots(Figure4;
p<0.05)butoveralargerrangeofdiameters(Figure3)
2Dr.ChuckCannonCenterforTreeScienceatTheMortonArboretumccannon@mortonarb.org
PhotoPoint:goodalternativemethodforconductingforestsurveys• Timerequiredtophotographaplotisindependentofthe
numberoftreesinaplot,whichincreasesit’sefficiency• Potentialforphotographstocollectincidentaldata,suchas
understorythicknessandcomposition,andtreegrowthforms
Lasermethod:pooralternativeforconductingforestsurveys• ComparedtoTraditionalmethod:equallyefficient,lessaccurate
DBHestimates,treesmissedmorefrequently,moreexpensive
• SynthesizedatacollectedbythePhotoPointmethodandcomparetheaccuracyofthedatatotheothertwomethods
• OptimizeprotocolofPhotoPointmethodtogatherthehighestqualityandquantityofdata
• EvaluatethepotentialinsightstheincidentaldatacollectedbythePhotoPointmethodcouldprovide
Area of Plot Area of Plot
