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Techni

JANUARY 1 981 pECEIVEONASA Sp FACItty J

is

Changes in Vegetation Spectrawith Deterioration of LeavesUnder Two Mothods of Preservation

M. L. Labovitz, F. J. Masuokaand S. G. Feldmann

National Aeronautics andSpace Administration

Guddard Space Flight CantorGreenbelt, Maryland 2071 1

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('IIAN(;I:S IN VI-(;F"fArION SITCI RA NI Ili UF,7'I:ItIc^ItA"I'InNOF 1.1?AVI:S UNDER I WO SIF I I IODS OF PRF.SERVA l'ION

M. l.. l abovitz and F. J. nlawokaCode 922

Geophysics Rianrh

S. G. FrldinannDepartment of GeologyUnive„ity of Maryland

Collrbe park, r.ID 207 71

.January 1981

n

CHANGES IN Vl-'(;F'I'A'1'ION SPFCI'RA %I'I'I II UETFRIORA PIONOF LEAVES UNUFR 'fw0 MI:TIIOUS OF PRESERVA'riON

t

AHS I RA(.T

Motivated by the nerds of a ficld project to measure spectral manifestations of mineralisation

in vegetation, the authors set up an exlxriment to measure changes in leaf spectra under diffcling

methods of preservation over time. The spectral measurements wer^ made using a three hand

kind-held portable radiometer wh i -h simulated three Thematic Mapper (TM) hands -'FM3, 'I'!N'.4

and I M 5.

Using a procedure identical to that used in an ongoing geohotanical field project, daily spectral

measurements of %% bite oak (Qucrcus alha) leaves unde. three preservation treatments were made.

The spectral Icadings over three treatments flesh, bottled and bal,,ged vegetation were indis-

tinguishahle in hands'I'M3 and TM5 for up to four clays after collection. After that time bagged

and bottled samples showed significant increases in Icllccted enelgy. This was interpreted as hcing

related to loss of chlorophyll from and dehydration of the vegetation. There was no significant

variation in the reflectance values from 'UN14 over preservation type for the experimental period.

This was interpreted as indicating the persistence of the air space-cellular interface.

AT'CEUING PAGF HIAMk MOT i mtzy

t)R^L^V PA

111

CIIANGFS IN %'I(. H A I ON S14-C1 11A N'I I II MATH IoRA l IoNOF I FA\'I-S UNDIA: 1 N'() X11 . 1 1 It )I)S OI ; 1'1:1 SI : K\'A 11ON

INfltt)DI VI ION

Pollalilt. Iadionu • Icts which :uc used to nleamm . iencctance float veectation in lilt . field

employ flic still as a 11 1 11t source. Mt.aaltcnu • nt of Ihi% Icflccicd sol.tt radiation even in tol ►oglahh.

ically --illlple .,^• as is complicated by solar it.nith .In l . le, lia/c and cloud cover. The tt.scatcher

Should Ity to .noid confounding • \.uiation in tctlectance associated \\ith Ihcse t.mitonntcntal

factors within %.IIiatit'll Iclalcd to the 1 1 11cnonle11a undet Andy. front All tAl'climental polsl" , live

this tail be achieved cIIhot by randonliiing the conditions is title \\hit'll nle:ISUIcInvllts atc made or

by test Iit Iing 0111selves t o one Sol of conditions, i.e., "krcl ► ing othcl things Constant." N 1111, • the

fit St .1 1 ,1110.IkIt. if Succt .ssfully a1 ► l ► licd, Icads to note t • cnt. 1.111c•nIts, it is an untenable mothodol ► 'yy

in held c\11clinlcnls as the \veathct is unhhcly to ch.11ll".e in a fashion to meet (Allot. constt.linls

(I\attioularly time conllaAs) of the c\pvtitncltt, and Iht. Ivsullin,, cllot \.Itiance may be too Lugs.

to 1,clnlit its to discern other 1 ► attt.tns in the (1ata. \1't. .Il t rinati\cly nlay Ic tliot ► till ntcasul^ nlrnts

to 1 ► cliods of hil • h ic Ili t11 .Ing It. and Ich11%vl) little cloud cowl. I'his too cart be a Sclious l l,0 , L nl

in Icnlotcly located field c lu• rintcnts \\ Ilk- lc obsvIvations must be made at Icyul.0 i Ill etvals duIing

the I'lkminl; 1W.1%( M. Ilo\\c\vr, oil \\ hen the conditions Illovl unsuitable, \c;-elalion play

be II.II1 s r"Itcd to allot hol loc:Itl\ ► ll, slot cot Ii ► r .l lh'Ilod of Iltlle .11ld Ilicastlled \k licit wc.11her contli-

tions alt. satisfactory. It lull.t be Atesst.d th.11 Icnloving vt.rctation floral the licl,l has the implicit

asst lnllit ion that its Iellt ova 1 and storage will not signili,. lilt ly change the Slicd1.11 pIO lit- IIit . s of the

vege I :11 ion.

I'll(- objectives Ilion of Ibis shiny wcm two fold: 1) to dciclmine how luny, lt.clf Ietloctance

t Icnlaincd unchanged after Icave-; are collected; and 2) to assess the "Ifects of leaf stotare n)cthods

on leaf Icllcct.utce. In This c\I^cIinlcnl two st\ , tage nit.thods weir cvalu.Iled: I) Acting the bores

still attached to blanches \\ hi g h welc placed in distilled \%Acr; and ) Iefligci -iting leaves ill

bags.

Elie picscnt study was dcsiLned to provide inft , 111whon to he used in vet;elalion

collection protettmes for a project studying the ietlect.mce of %Nldle oaks(Quercus affia)1; ► owing

on %oil% in a uiinc1.1liied It-t;ion (metal sultide c), Of p ► inrary unportance to this ► ew.rr:h is the

%cnsitivity with %%hich we ilmy detect %trees in vegetation.

While tilt- s.iniples used in this stl ► dy were diaHn from five white oak trees E;itm ing .dolly. the

t-dVe of a wooded lot in Givenhell, M.1iy1. ► nd, the rr.ulls of this study ace conside ► ed applicahle to

otht-I li.udwood species growing in tt-nilk • iete I. 1iin.1les and will provide us Willi:

(1) the lo\kcr limit on the Ncn"ili%ily of the expc ► iint-nl:-1 pitItkIluic I nre.iNu ► e stress;

(.') :in cslim.1te of the tune period for which one call preserve vegetation, spc cifii.illy Iv.l\rS,

.111d still iclatc specti.d leadinf;s front the ^I rt-tation to ► t-adinp nradt- in the field;

(3) a comp:uison of two .imple methods of %cl;etation picwl vat ion.

Nil . I Ilt ► DtIII OGY

Deily it-flcctattce nn• asruemcnls of ve" ..ctation \%c • ► c 111.1,1e in tluct- "pt-01A hands to dete ► niine

what ichliomliip, if ally, existed hetween spccti.il ► ctlt-ct:utce and Ow incthod of pit-servation or

the It-rtl:th of storage time. Itt-flrctarre nieasurenu • nts were noted for vcye • lation pieserved usint,

two methods: 1) refrigerating Ihe • leaves in paper hags and ') placing h ► ancht-s will ► leaves intact

M tlktillcd water. I • hc wflect.urce values of the 1c.IIIcs \ke ► e coiiipaied to fleshly clipped

vegetation for a period of eight days. Rvilectanct- measurenwnts \%crc made using a there hand

hand held radiometer (Tucker et. al., 1981).

Mind Ilr • Id R.utionreter

Fhe radiometer used possesses two silicon kit-tectors which hev•: a sensitivity range of approx-

innately 0.4 to I . I Jill) and one lead sulfide detector with a sensitivity range of approximately I 1

to 3.0 pin. File spcctr.rl range of the device was dot-rnrined by mounting init-lfcr t-nce 1 ,111cls in

front of the detector. The radiometer was confirmed to mimic three hands of the Thematic

Mapper (fM) sensor which will fly on I in 1982 - 'TM3 (0.63 0.69 pin), 1 M . 1 (0.76-0.90 pin)

2

end I M5 (1.55 . 1.75 Nm). File transmission turves for the liltcrs used in this research :uc given

in Figure I. 'these bands ate used bvtatrse of their relation to the chlorophyll content, inesolihyll

structure and 11 1 0 content, tespe.lkely, of vegetation (Tucker, 1978).

P.lodes of Preservation

I'he population of leaves used in the experi ► mnt was restricted to those from white oaks, the

Anne species used in our geobotanical study. For reasons of logistics, tires within the confines of

the Godd.ird Space I-liviil ('enter weir used. All file cuttings (samples) were second year or older

' twigs from five randomly .c • lec ted tires. the s.,,nplrs were selected tandomly with resprcl to

4^tientation (ai.innuth) and height in the c:unopy. It ,. Al, 48 samples were taken, each containing

approximately 25 to 30 leaves. 'I • he samples were rand y ► nrly ili%ided into two groups:

(1) Leaves ft(wnn twenty-four of the samples were removed from thi • ir branches and placed

in an orderly mauncr in paper bags, ^^hich were then sealed .% nth tape and carefully (it) avoid damag-

ing the leaves) stored in a ieftigerator.

(_') 1 eaves were left on the I'tanches of the other twenty four To enhance water

► hsotption, approximately 3 to 5 inches of balk was stripl ed off of the bottom part of each branch.

The branches weir their set in clec ► n bottles filled with distilled eater. Distilled water had to he

addret to each bottle daily to tclilat e water lost clue to evapotranspiration.

In addition to the ba txed and bottled sannples, flesh samples, cut Bail . only minutes before

nef1L • L ti% ity readings were to he made on them, acted as a control on tine other ► wo modes of pres-

en:rtion.

procedures of Daily Measurements

Daily reflectivity nne:rsurrnnents proceeded in the following manner. Readings were taken

only under clear weather conditions in diie • ct sunlight. 'ro reduce differences related to sun angle,

all spectral measurements were taken I I AM and 3:. 0 IN Pastern Daylight Time (10 AM -

2:30 1'M Solar Time). :III the inea%mcnivnts \%cte taken in the principal plane with the sensor

3 ,lair; ^; ,u, i yl;!; IS' )^' N''N it QUALM

C, C3 0 as Ns 1^ CY

NOISSIMS,NViii lNi,'U-ld

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positioned approximatt,ly 100 off nadir to prevent tasting shadows across the "uttvlc. My day

mo bottled and two hamed samples were seki NI at random for incamurcincrtt. 'fhr tetlectkity

rttrawn • nt(• nts Here Heide in a cleating near file tires n1lich had ptovidrd all (► f tilt, samples, in

LOW to i ►)suic fresh .tidings fot the control rradinys. Smiiplc nteasutentents ►%viv randotuiied

v► illt rryxtl to tilt- mode of ptcservation (balxed, bottled, of fit-01) to tonttol for polential biases

attotnpanVing the •taut ill) of daily e ,%perintt,ntal procedure :md the time of day nu•asulrntc•nts

were taken.

I'hc leaves %, etc scpatated (those in tilt . bottles ^kerr removed font their branches) and Flared,

ada%ial surface tip, in a ntonolayer on a I foot %quire, 1/8" thi, ". .duntinunt plate, so that they

,o ► t,rrd the entit y plate. Fhe pLttr's surface was paintt,d with a polassium silica b.rsrd flat Flack

I'mi ► t posst,ssin l• a ► rty low rt,tlectance over Ih; %jwcltal legion which includes the I':rtnfs e\.1ininrd

here. A second plate sutf.i,cd nilh b.uiut:t sulf.dc "as used as sland.ud (J. SA1111, personal

ontntunication, 1 980).

Once the sample was ptcpated (tin file black plate, a photowi.tllh na% tAcn showing tilt' ► cprta-

lion :utrtolatrd with file date, type of preservalion, and tilt' IL-plicate number of the sample. A dark

rradinl;, atltir ► ed by covet inl; the r.-thontcler's sensor. nas also taken so that drift could br noted

and t l iv lead sulfide detector m:oed. 'ncc nte:rsmements were made at a heirht of apprmin:.ilrly

20 ccntintt,tets (N inches` above tilt- plate. Since the field of view of the sensor was 12.5 drltrces,

energy fiont cut atea of al,prmintatrly 15.5 stlti,ur centintrtrts was nuasurrd. keadin s were taken

altetn.ticly on the Ic.lcrs and the b. hnn sulfate panel. A pair of readings look approximately five

to ten .,ccon(is .md several pails of tradings were made in an attempt t o minimirc instrumentt ,

► aviation. The pracedutt, was repeated for all G sangTs (2 or each mode of preservation).

The actual length of the exprtirrtent was 9 days, from September 3 to September I I, NNO.

['he sarttples to be bottled and barxcd Here all cut on the 3rd, and the teflettivity measurements

A ► ,t

we:. taker, front the 41h to the 1 1 ill, inclusively. No readings were taken oil the 5th of September

due to a heavy cloud cover.

kFSULIS

Fxpc ► imental 1,v%ign

The proceduredescribed in the previous section was set up so that the specific questions out-

lined ill Intioduction could be answered. 'fo answer the ,,. questions we set up -I

.m:ilubue of the expelintcntal situation. Tic experimental design, is that analogue and its algebraic

operations are performed using; a )rocedwc known as analysis of variance (ANOVA) fisher,

1970. Within the ANOVA procedure file variation ill n ► casrremcnt is partitioned among sources

of vari;ition, these are equivalent to the subjects of the questions (e.g. Mate since clipl•i .g of vegeta-

tion). The question itself is constructed as two hypotheses (the null and alternative hypotheses)

which sae structured to include all poss'ble answers to the question. A decision as to which

hypothesis is more likely correct (which ill call trawdatcd into an answer to the original

question) is based upon whether or not the source of variation ", • \plains" significant amounts of

the total variation. Ill section we formally describe the experimental design.

In this experiment we have explicitly t aken accomit of two factors (also known as main

effects) day after clipping; ((late) and type of preservation (type). Since the experiment was

performed on seven days, we say that the date factor has seven levels. Similarly, the type factor

has thice levels - fresh (fr), banged (bg) and bottled (bt). For each combination of date and type

level, there are two leaf samples or replications (reps). Measurements of the reflected energy ill

bands TM3,'l'M4 and TN15 were made on each rep. These measurements are the dependent vari-

.ables for this experiniciii. llecause cash level of the date factor occurs ill the experiment in com-

bination with each level of the type factor, the design is known as a factorial design. T'hc construc-OP

tion of a factorial design permits us to examine the interaction between the main effects. ' he

meaning of the interaction effect will be discussed below within the context of specific data analyses.

I'lle Inublt'nt is Own to el► .Inline %aliation in it-M- l.lnt a nlr.lsutenlculs and .IS.il;n it to file

tic f.tktor. the I) lie cwtor, file inlct.tctiun t,t't.%cen date mud type ill %ome c, , licclion of non-

""'third rlfrcts (flit- vibe). I'lle •,Iluctutal form of tilt' Iclation•hil ► I+cl%ccn It'tlectallcc and the

SOUIit• S of v.Iri.Itioll is Vilell by

ycI)kµc Inc flij faif,'eijk

whrle:

1' ^k is tilt' la Teem of 1 loporlioll of Inlet' timer in band c (c : I, 2, 3) for flit' k ill Iev

(k I , 2) sul•je.lcd to flit' I lh type of l , tcsctvation (i - 1, 2, 3) and mv-v-mcd ► it ► Ile

^ th day (i -1,2,...,7);

i v, tilt' tl^, 1.111 Int•.tll Icf e: t lllce front b.ntd e;

1

tI^ .lit' k01Mants subject to the IcAIi:ti ►► n •u^ Cant) it-lift-will the variation con-

ttibutcd by the I th nu• thod ( ► f lit cscr vat it 'll to the Ieflectance in band .;

l I( Me indclicndc lit ly mid not nl.tlly li%ttibutcd t.ln ► tum vari.lbics with mean equal to 1cro

Mid vati.u ► ce equal to o3t`) (NIT) (0, ok ) )J, and It'l , tescnt tilt' %miatiolt contliblttedlI

by thei th date to the It'tlect.ulce in b.u ► d c;

uif .IreNII) (ll, (', i),r? t') ) random vatial , les suljvct to the It'striction !, n,R rt 0 for all j.1, IQI 1 ^ I

aml Ic1 l Irsents the variation cont l It'll It'd by the interaction (if the l it, type of 1,10-rrva-

tion .u ► d tl ► c nth date to the reflectance ill c;

t ^k arc 111) (0, oc 2 ) tan ' lom variables rrl , lescntintt all other Itnsl,ecificd sources of valb-

tion, commonly ca l lt'd the eI tor;

i Off, apU , and f la k :uc in ► tcl,rn ► lent.

t

I '

(1)

1-

If we take the exp ectalion over teps for each ttcatrnent and •ulHrac t tl ►e ovrrall mean (N),

equation (I) becomes i

and file % mialice of Yuk is given by

Var(Y^k ) : Var^Y yk ) ' o t) + (/) e,2 uc (3)

Ille I'roblt,n, is now cic.mly to determine which of the it-fills on the ti k ht hand -,idt• s of rtluations (2)

and (z) are Ilkely to be nun /ero. Ilii% dett,rmrination is accon. 4 ,1khed by Im!titio ► ,ing the total varia-

tion ammig lhr above trims and con,p ► aring mint of silua ► rs.

In sunrnmry:

(1) the c\IvImienlal dt,sigri is . ► two- factor factotial design;

(2) the Bait, factor has sc%t,n lcwls and is it effect;

(3) Iht, typ ►e factor h.i. them levels and is a fi ,ted t-ffect;

(4) the I ► trsence of it now/,, ► tern, among the ties %% III imply that not all preservation Mlles

have the same effect on reflectance;

(S) 1he 11tv%ence of a nonzero variance among the ii^'s will imply that the reflectance Changes

wide 41.itc;

(0) the presence of a nun-mo variance among the (10"'s will imply that changes in relleclance

over date are not tilt , san ► c for each p ► resmation type.

Data :analysis

I'able 1 I-J%vs the results for the two factor-mixed effects-factorial design descr;bcd Ill I ► revi-

uus section. Fach sub-table is an analysis of variance for one of the dire TSI Hands. 'Die analyses

were accomplished using the HNII W3V p ► ogram (1cnnrich and Sampson, 1979). Computation for

these and 111 other analyses ill paper werc perfo ► med oil IRn1 370/3033 computer located at

the Pell nsylvania State University. III sub-table the first three sources of variation correspond

to a t,, Q and tipIj rt• spectively. Ilrt, important points to note arc:

8

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(1) All tlir. t --i t es of variation .ire significant at any cor.ti, ;.nunal a %el for 1' 13 and fM5.

(2) 'fheic is no evidence to indicate that fire type of pir%ervation of interactions -ire %q, nifi-

cant contributors to reflectance in TSI-t. Conclusions about the d.rte effect .ire less

certain, curd since we are icing an a = 0.02 level ()f significance for individual tests in

I'.1")IC 1 we conclude that date is 1101 significant.

If we examine the plots of the treatment means over date for each type of ptcservation (%cc

Figures 2 to 4), we can develop ten t ative hypotheses for the results of Table I. In the hones associ-

aced Aith'IM3 curd ISIS, it appeared that the type of preservation was not an important factor f.,,

the first fee: days after F lipping. Ilowcver, as the time since clipping got longer, file differences

ni the rrflr(tallce bctwcen fresh vc ► sus hayged vid battled +111 1 )lcs increase. This is the paticrn

of variation being .aphrje(I ire the type and date type interaction tctnrs of the analyses of vatianc•e.

1 N14 (I : il:ure 3) is c•onsidcrahly more difficult to interpret. Cleady the date effect is significant

.end the figure shows that there is an incrratse in reflectance to the middle of the rxlx • riment with

the reflcetances of bottle and p a l-i"ed saillples decreasing towards the end of experimental period.

This trend would likely have yielded a significant interaction had the exp:timc• nt Listed ]()tiger.

Phis pattern will be dealt with fur then in the Discussion section.

Pattc ► ns of variation were examined further by looking at cubselsof the data. We first wished

to ► rile out that the variation noted was due to environmental effects such as changes in atmospheric

conditions or systematic changes in the measurement procedure over the experimental per iod.

tiince the fresh samples were our standard for comparison and were not s(,hjcc;cd to a period of

oleterioration prior to measurement, a significant date effect among these samples would be at-

ti ibuted to external effects. Table 2 demonstrates that there was do significant change in the

reflectance of fresh samples over (late for any of the spectral bands. Next, to examine the conjec-

lure that there was w difference in the reflectance over the three preservation types for a

finite but u title tern lined period of time, we examined data for the first three experiment days

10 IRE

• FRESHn RAGGED

♦ HOTTLED

(* COINCIDENCEOF SYMBOLS)

15.00 -

14 25 -

13.50 F-

v 12./5zQHv 12_.00 -lLJll..W

F—11.25

zwUw 10.50CL

9.15

9.00

l_— ---1-- -- --1 1 F 1 1 1

9/4 9/5 9/6 9/7 9/8 9/9 9/10 9/11

DATE

I'igurc 2. Means of replicated reficctancc measurements from 't -M3 over timeby preservation t^,pc.

55.5 r

54 0

57.5

w ^*/1 *--Q b1.0

Uw ^JLL 49.5WlY

w 48.0 -UccwiL

46.5 1

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45.0 U BAGGED

A BOTTLED

43. 5 ( * COINCIDENCE OF SY

L-------1 --9/4 9/5

_.l - --J9/6 9/7 9/8 9/9 9/10 9/11

DATE

Figure 3. !`leans of replicated re flectance measurements from TN14 over timeby preservation type.

A

12

:+ice

13

49.5• F

n RA

48.0 A HO

1* COOf

46.5

ILv 45.0zQF-,^ 43.5_JLLWCr

7 42.0

uCL 40.5

*G

39.0

37.5

9/4 9/5

9/6 9/7 9/8 9/9 9/10 9/11

DATE

Figure 4. Means of replicated reflectance measurements from TM-5 over timeby preservation type.

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16

Its are given in fable 3 and we noted that there were

no significant effects in any of the three spectral bands. However. -when we examined variation' 1

over the entire experimental period solely in the bagged and bottled samples, (Table 4) we saw

that the:uiation in 'I'M3 and 'fM5 was significantly difretent for at least one of the experi-

mcni days.

I

The previous three results lead us to the logical conclusion that the significant variation

found in the date effect is due to the changes in the reflectance measurements of f ete bagged

.end bottled samples from the early to late portion of the experiment. It is clear front file pre-

vious results that the preserved sample reflectance does riot differ significantly from flesh cutting

responses in the early stages. 'The point lit of the change earl be determined by setting up

a series of orthogonal difference contrasts (Da) ton, 1970). These contrasts are based upon the

crnnhincd means of :he bagged ant, bottled samples over date. The coefficients associated with

the diffCrertce contra sts are gkcn in Table 5. Notc that there arc six cuntr.+ats which correspond

to the six degrees of freedom associated with the date factor. The logic beiiit,d these contrasts

is that we step through the v .-perimcnt days, starting with days 1 and 3, comparing the meant

of At the previous days with the current one. For example, we first compared the combined

mean of banged and bottled samples for day 1 versus those of day 3, then we combined the

means of days 1 and 3 and compared this new mean to the mean for day 4, and proceed in this

fashion until we were comparing the combined means of day I through 7 against day 8. The

coefficients given in I'able 5 are the weights by which we multiplied the means for any given

contrast. Use of the contrasts allows us to orthogonally decompose the sums of squares, which

upon suitable manipulation can be transfor ►ned into a t statistic with 21 degrees of freedom

for each contrast. The results of these analyses are given in Figures 5 to 7. Since we were

performing 6 sequence tests for each band we have used a Bonferroni ad'ustntent Fishcr, 1970I

to adjust . the family 'confidence limit (for each band) to 0.05. This means that the a level for

each t test is set at 0.05/6 -0.0083, which is achieved by using t (v = 21, a = 0.0083) ^5 2.84.

C

A dwhcd line cotre VOIldin g to this v ;title is present in etch figure . - We nmted that for I'M3 and

TMS the first signircanl 1 value ottms at contrast Iluce giving a ch;tnt,c point I'etween the fourth

.old fifth day. Fill Ihct, their was no significant cunt ► a•t for I M-1 (Fil-me 6); Ih is was in agicertn•nt

%4 11 the results of'Tahles 2 and 4.

'fable 5Orthogonal I>tffcrence Contrast Coefficients used in Iletcrniining first Chan{;e Date.

Coeffic ients

Contrast Y111 5 B3. YH4. N? HS. Y It 6. Y H7. YNx.

I I -1 0 0 0 0 02 I 1 -2 0 0 0 0

3 1 I I -3 0 0 0

4 1 1 I 1 l 0 0

5 1 1 I 1 I 5 0

6 I I I I I I 0

1liscussiutt

In this ex{1criment we have reported that no si; ficant chvlge occulted in file Icllcctance

Ill .111^ of file thtce spectral Bands for clipprd haves in, cithct method of ptesct%ation for at Icast

four ,lays after clippinit. Beyond four Mays, reflectance in hands 1 and ? from ht and ht! leaves

inc as • t th • en of the c^ • • rinirnt. No s tatistically si mificant chines ocr cutred in hand 2rt. c d u ^ d { c t.• L

It'11C:tatice floill the thtce twatnn • nts over the expetimcntal pciiod. Ilowever, examination of the

hand 2 plot, Figure 3, hints at an initial increase ill followed by a decline ill reflec-

tance vahics for the hl and bg samples. Further, the restOts suggest that leaves placed in paper

hags have ► cflectances closer to those of fleshly clipped Icaves than leaves left on the branches and

placed ill water. however, the differences iu reflectance were not statisti.ally siellificant.

These Icsults are similar to the conclusions of Keegan ct al., 1955x, 1955b. In these Icports,

personnel at the National Bureau of Standards studied ieflectance changes of white oaks under

natural drying conditions oc stored ill containers.

18

Ll

F—"

CON FRnsT

0.112-50

-1.3940

t

-2.9941

-3.8901

Al

4.7891

- 5.3039'-

Figure 5. Values of t statistics for the orthogonal difference contrasts fromc0111bined means of bagged and botticd smnple • s for TM3.

19

f

---- - ,.. ^rVAt.^t 1 T

20

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.. AN ^v+WO

> Ov

^Dv700

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4.5534

-t IV 21, o f005)

Figure 7. Values of t statistics for the orthogonal difference contrasts fromcombined means of ha,ded and bottled vinihles for TMs.

-16

21

:1

22

-_— 1

I

TT.STRUCTURE

^R 60 MGMEN 1 S WATER

w

Z 50 -Q

v 40 -wLL \ \u LL 30 -

L'jJ ?0 \\w \w- \ \10 ,\ \CEc^ L I I ^ l^ 1.1 1 I 1 1\ :1J 1 I I 1 ^J I l

0.5 1.0 1.5 2.0 2.5

WAVELENGTH (pin)

figure 8. Spectral reflectance of glcen Icaf vegetaliun over 0.35 . ' 50 11111

(modified after fucker, 1978) showing hands u%cdand dominating plicnonuna.

4

We may interpret these rcrults using Figure 8 modified from Tucker( 1978) illustrating the

location of file three hand held r.idic^tnefer bands and the phenrnncria which dominate variation in

regions of the green leaf reflectance spectrum. The first band 'I M3, (0.63 to 0.69 Nrn) is centered

un a chlorophyll absorption maximum. from the onset of leaf senescence, about day 5, to the

end of the c• xlxrimc ; file reflectance of clipped samples increased dr.onatically to 'I'M3. An

increase in reflectance in file visible region is well documented for diseased, stressed and senescing

' leaves and has been atttibuted to a breakdown of the chlorophyll pigments in a leaf (Gates el al.,

t 1965' Knipling, 1970 Kabideau et A. 1946). 'the second band ,1 514 0.76-0.90 ern falls within

a region of IIit- spectrum in which Icaf structure goverm changes ire file infrared reflectance (Gates .

ct al., 1965; Knipling, 1969; Gausnr:na ct al., 1970; Sinclair, 1971). Inflated reflectance in the

It-if is due to scattering in the ntesophyll Layers. Ire the pallisade :end spongy tnesoph) ll the cell

walls act both is reflecting surfaces atul boundary% where refraction occurs as the IirliI passes

front air filled cavities into the hydrated cellulose of the cell %calls. Dining the early stage of

senescence an increase in reflcctarce may oc,:ur as adjacent cell %%':ell% arc tern ap:ut creating more

reflecting surfaces (Knipling, 1967). In Late stager of senescence, reflectance decreases as cell

%%ails disintegrate (Knipling, 1969). '1 his would suggest a pattern of reflectance similar to the one

we witnessed, i.e. a slight increase in reflect m cc prior to fire decrcau in reflectance over time.

Band 3, T'M5, of file hand held radiometer (1.55-1.75 pin) measures infrared reflectance between

two strong water absorption maxima at 1.45 Nm and 1.95 pin. Above about 1.3 pill leaf senescence

it manifested by an increase in reflectance which is due to ,:te loss of water by the leaf (Myers and

Allen, 1 x)68; Thomas et al., 1971). This too confor ins to the pattern of variation we sec in F igure 4.

In runtmary, then, referring back to the questions set out in file Introduction:

(I) I'hc n ► easutenrent hru.cdurc used is sensitive enoubh to discern documented patterns

of variation in reflectance measurements which have been associated with changes in the

leaf pigments (particularly chlorophyll) and file water content of drying (stressed) or

^- -` senescing vegetations

23_uRIGIIiAL eAGi'q, 18

of POUR QU ALM

24L -- —

(^) We stay use rcfle:lancr nn.tsurrnu nts from cliched %cgetalion for up to four days and

be able- to directly relate the results to rte%illy ricked vegetation.

(J) Neither of file two method% of lit, - c ► vation %%.is slatistically sul ►crior. Ilowever, the

Ix ► t^gcd samples were ca.icr to handle and al ► oc.ned to yield ivnectances which remained

clo•cr to the flesh •amrles.

A, knowledremcnts

The authors would like to thank their colleagues Ross Nelson, C. C. Schnctiler, C. J. Tucker

,t!Id W. Web%fet for their careful revicHS of thenta1tuscript. We would ako like to ackilowlcdtie

file thoughtful criticisms of J. C. Gnffiths, the Department of (ocosciences, the Pct nsylv.mia

State University. We also al ► l ► teciate the efforts of Catol Patten of file Codd.ud library in l ► roi ► il ► tly

securing, needed interlibrary loans.

IZefercnccS

Dayton, C. M., im,phe Desi g n of Fducalional Fx1 ►eriments, New York, Mc Caw-hill Book

Company, San r7 rancisco, 441 pp.

Fisher, R. A., 1910, Statistical Methods for Research Workers, 14"' ed., New York, Ilafnr.r Press,

362 pp.

Cates, 1). M., if. F. Keegan, .1 C. Sch tetcr and V. K. Weidner, 1965, Spectral properties of pl.mts,

Applied Optics. V. 4, No. 1, p. 11-20,

Gauss an, If. W., W. A. Allen, R. Cardenas, 199, Relation o1 li g ht reflectance to histological and

physical evaluations of cotton leaf matm ity, V. 9, No. 3, p. 545-552.

Jcnrich, R. I. and 1'. Sampson, 1979, I'3V: Cenctal Mixed Model Analysis of Variance, in: BNIDP

Biomedical Computer Programs, P-Scrics, W 1. Dixon and M. B Brown, eds. University of

California Press, Berkeley, CA, p. 581-598.

Keet , :ur, I I I , J. C. Schleter, and W. A. Ifall, Jr., 1955a, Spectrophotomctric and Colorimetric

Change in the leaf of White Oak free under Conditions of Natural Drying and Fxcessive

Moisture, unpublished report, National Bureau of Standards, Report No. 4322, 44 pp.

Kccr^an, If. J., J. C. Schk • ter, W. A. hall, Jr., and G. M. Ilass, 1955b, Spectrophotometric and

Colorinu• tric Study of Foliage Stored in Coveted Metal Containers, unpublished report,

National Bureau of Standards, Report No. 4310, 74 pp.

Knipling, E. W, 1907, Physical and physiological basis for differences in iellectance of healthy

and discascd plants, Proceedings of Workshop on Infrared Color Photography in the Plant

Sciences, Florida Dept. of Agriculture, Winter lla%en, Fla.

Knipling' E. B., 1969, Leaf reflectance and image formation on color infrared film, Remote Sensing

in 1 7 cology, Philip L. Johnson, ed., University of Georgia Press, Athens, Ga., p. 17-29. -- -

---- ii 25- - - ---

Knipling, E. R., 1970, Physical and physiological basis for tlic reflectance of visible and near infrared

radiation from vegetation, Remote Sensing of the 1 7 nvironment, V. 1, No. 3, p. 155-159.

1

Myers, V. I. ind W. A. Allen, 1968, Flectrooptical remote sensing methods as nondestructive testing

and nu• aurring techniques in agriculture, Applied Optics, V. 7, No. 9, p. 1819-1828.

Rabideau, G. S., C. S. french and A. S. Molt, 1946, The abso ► ption and reflection spectra of leaves,

chloroplast suspensions and chloroplast fragments as measured in an 1 1 Ihricht Sphere, American

Journal of Botany, V. 33, p. 769-777.

Sinclair, f. R., R. Ni. lioffer, M. M. Schreiber, 1971, Reflectance and internal structure of leaves

front several erops durin;t a l'rowing season, Agronomy Journal, V. 63, No. 6, p. 864 868.

'fhornas, J. R., V. I. Myers, M. 1). 1Icilman, and C. 1.. Wiegand, : 0 66, Factors affecting light ietlec-

tance of cotton, Proceedings of the 4"' Symposium on Remote Sensing of the Fnvironnn•nt,

Ajrn Arbor, Mich., p. 305-312.

fhornas, J. R., L. N. Nainken, G. F. Ocrthcr, and R. G. I;roNn, 1971, I stimatiut; leaf water content

by reflectance rncasurcrnents, Agronomy Journal, V. 63, p. 845-847.

'Tucker, C. J. 1978, An evaluation of the first four landsat-D Therrratic Mapper reflective sensors

for monitoring vegetation, Photogrametric Fnl'inecrin g and Remote Sensing, V. 44, No. 6,

p. 1369-1.180.

'rut kCr, C. J., W. H. Jones, W. A. Kley and G. J. Sundstrom, 1981, A three band hand-held radiom-

eter for field use, Science, V. 211, p. 281-283.

ultl'^'2'; tiCI F' ^'.N^.l (l fAi,JT.

• 26--

1'It;urc ("II ► tiolls

Figure 1. Srectial sensitivity of tutee inlcrfcicnce filters used in Ihic study.

Figure 2. Means of Icrlicated reflectance nuasurem cnts from TM3 over time by preservation tYpe.

Figure 3. Means of rcj ► licated renect.mce mcasmements from 7 M-I o%cl time by preservation ty1w.

!more 4. Means of n•plicated reflectance nleasuicnlcnts from '11W over time by rlcservation tyre.

Figure S. Values of t statistics for the orthoronal difference contrasts froln combined means of

bagged and bottled sanll ► les for 'I \13.

Figure 6. Values of t statistics for the mthogonal diffvience contrasts from combined means of

bal,jwd and bottled samples for FN14.

Figure 7. Values of t statistics foI the olthoronal difference contrasts floor combined means of

I -w,, ted and bottled .im a les for'I"M5.

I 'igurc 8. Spectral Ieflectance of green Icaf vegetation over 0.35-2.50 pill (modified after Tucker,

1978) showing hands used and dominating 1 ► henonie1a.

27