Chapter n'

Fossil pollen study from p e ~ t core samples

4.1 Introduction

4.1.1 Archives of proxy records

The htstortcal and lnstrurnental records about vegetation. cltmate, ctc. prov~de

lnfonnat~on for only a few centunes They arc very few In number and arc restnctd to

spectfic locat~ons Hence, the vegetatton changes and In turn the cllmauc vanabrl~ty In

the drstant past can be understood from the study of naturally occurring geolog~cal

depostu. found both on land and In water D~ffercnt klnds of depos~ts and technlques are

used for tnfemng the palaeocl~mat~c evtdences In thcx natural deposits. Temstnai

dcposlts Include pear depostts, lake scdtmcnts, cave dcposlts, tree-nngs, loess and sand

dunes Ocean deposits constst of deep-sea sedtmcnts, coral mfs . etc Wlth a sultable

techntque the proxy records can be used to retneve tnfonnatlon preserved wlth In these

natural dcpos~ts (Bradley. 1985)

4.12 Soums of fossil polkn

SuJI Pollen grams gets dcposttd by dtfferent modes of transportation

wtnd. air, streamb from the surmundlng vegetatlon for thousands of years. These pollen

gralnr that arc rctrleved from the peat deposits reflects the past vegetatton However.

some of the pollen grains may not get fossilized. Pollen assemblages arc found botb on

I d and in the ocean and constitute impoltlnt proxy indicaton qf thc cllrnatc. The

lnterpretatlon of these pollen assemblages depends on Ihe nahlrc of the mnterid from

whlch they are retrieved as they vary from one swm to another (Moore cr al., 1199)

Pollen grams present In younger pans of the geolog~cd column can provide VIUI

lnformat~on about the nature and extent of plant communities living In the recent past.

Pollen grams and spores present in the sediments has always been a mainstay of

cont~nental palaeocl~rnat~c reconstructton. They provide infonnat~on about the changes

In the compos~t~on and spatial panernlng of late Quaternary vegetation that can be used to

~nfer rcg~onal palacocl~rnat~c changes. Pollen analys~s also provides lnformat~on on

changes occurring both on land and In the water body itself

The results from pollen analys~s arc used to establish palacoenv~ronmental

records, and. ~n the recent days. more ~mpomtly for developing models for

reconstructing cl~mate patterns ~n global change studies. Vegetaoon and cl~matic changes

of Quaternary penod arc reconstructed from a core of lake mud or peat, or sometimes

cores from the seabed. Small samples of sediment taken from intervals throughout the

core arc separated and chemically processed to &move dl the matend except the

rcs~stant pollen and spores Because sed~ments in a lake build up over tlme, the sequence

of samples from the bottom to the top of a core prov~des deta~ls of vegetation change over

t1me

Peat bogs arc one such natural depos~t that IS umque among ecosystems

preserving the blodlven~ty of the pa\! Peat depos~tr occur cxtensrvely ~n the temperate

reglons (Barber. 1993) Peat deposlts ~n the troplcs arc not very common, but they do

occur in the hlgher alt~tude reg~ons ~n the valleys and hollows Many studies on the

quatonal peat bogs from South Afnca have b n n c a m 4 out successfully on drfferent

palacocl~mat~c lndlcators such as pollen, (Bonnefille er al., 1988, 1992, Bonnefille and

Mohammed. 1994). al'c and a'% (Aucour rt a1 . 1993).

an8 $40 dud wp,+ wd4 -,nly P & dw:d 6(,

Peat fonnaf~on m the accumulat~on of organlc detntus from plant origin/ Low

temperature. low rate of mlcrob~al decompos~tion and water logging anas arc the pnclse

cond~t~ons for peat fonnat~on In Southern Ind~a. peat bogs an found rn the valleys or

basins ~n the hlgher altitudes (>I 800 m. a.s.1 I of the montane reg~ons ~n the Western

Ghats Stud~e\ from thr\ region prov~de the h~story of the vegetatron and cl~matlc

change\ datlng back to the late Quaternary Pollen &4 (Vasanthy. 1988: Gupta. 1990 and wd

Sutra et al 1997), d " ~ analyses. (Sukumar et al., 1993; Rajagopdan, ef d., 199%) an fi

camed out and also the future impacts of the montane ecosystems in the higher alt~tudes

can also be prcd~ctcd uslng these peat depos~ts as palacoanalogs (Sukumar et aL. 1995)

The pea depostts are featured tn the valleys of higher altitude montane regions

(>1800rn a.s.1 ) of the Western Ghais of southern India. These p a t bogs arc formed In

the valleys due to the frequent water logging. macmbtc condrttons and low temperature

In the montane replons of the troptcb The pollen gt;uns p ~ r v e d In these pa t sampler

%dispersed and depoblted from the vegetaiton growing In the valleys. and from the

surrwndlng rnountatn slopes and folds featunng grasslands and sholas respectively.

The locatton of the study stte 1s shown In (Fig 14) in Chapter Il Sandynallah

swamp from where the core samples were collected 1s located bctwan 1 1 O26' 12" N.

and 76' 38' 24" E ai an altttudc of 2200m i~bove sea level wtth a mean rainfall of 1400

mm annually

Two plo of about ? 5 m depth were dug In a bastn near Sheep B d n g Station

(SSBS) In Sandynallah regron of Nilpn htlls Sampling of the first core (referred to as

SD was c m e d out In the year 1989 (sampled earlter by Sukumar rt aL. 1993). The

second and thtrd core (referred to as SIl & Sm) were sampled In a dy -n, I e.. In

February 1993. wtth the help of sctentlsts from the Indian Institute of Science, Bangalore

and Phystcal Research Laboratory. Ahmedabad. During the dry season, the water kvel

bclng comparat~vely low In the bogs. appear relmtvely dry and thts makes the sample

collect~on a ltttle eaier. For the pollen tnvesttgatton studtes cores SI and Sm cores were

used. The pa cores SI and SIII are sampled from the same basin. whtch mre few meters

(.bout 15 - 20 m ) apm from om another. ks from SI con ame collected.

each of 5 cm depth at every 10 cm ~ncerval. The depth bctwan 195 to 227 cm were lost A

dunng collect~on. These points an about 37.5 cm and would have been d d i t i d 3

s A p k s ~f 11 were not lost dunng collection. The samples from SIB core were cdleacd

from the side wall of the pit, eech of 5 cm depth. at 10 cm intervals up to 100 cm.

Contlnuws sampling was done from 100 cm to 159 cm. Peat samples from 156 to 255

cm (referred to as SIIIB) were colkcted continuously from an adjacent scaioa m the

same p ~ t beyond which water s tana l seeping into the pit and sunpk cdlsctiae wrr

~mpossible. Samples were packed In pdythene bags to avo~d contamination, Wzkd md

stored a 7°C to mlnimlze dctenorat~on. Selected samples were radiocarbon bscd rt the

Blrbal Sahn~ lnstltute of Palacobotany (BSIP), Lucknow. About 5-10 gnvns of the subset

of the peat samples was chemically veoted to carry out the pollen analysis.

The general stmtgraphy of the baslns has been described elsewhere (Rajagopalan

er a1 . 1978. 1980. 1982). The peat bogs In the Sandpollah region iue lowland

format~onb, occurring In valleys (Fig 4.1 ). The pea samples collected from Sandpallah

ba~cn were dark brown In colour and contamed plant matter in vanous stages of

decomposlt~on Field observat~ons of the sediments did not show any shup

tmarcat~ons, but the level of decompos~t~on in d~ffennt horizons showed a great

vanallon. The swamp deposits comprised of clay. black and brown silty organic mud

The organic mud (black and brown) is SOH and sticky when wet and dries to a hard brittle

mass. The bottom sediments an pale yellow clay w~th fine to coarse sand. The p a t

samples could be broadly classified as black or brown peat with organic plant muter.

black brown clayey peat wlth moderate and totally decomposed organic matter, and

sandy or silty peat towards the base. A schematic scct~on (based on Rajagopalan, 1996)

of the peat samples collected from SIII & SUIB 1s shown ~n R g 4.2 The lower depths ~n

the \econd core (SIII &SIIIB) Indurate yellow clay IS f m d probably by weathcnng of

the underly~ng latent~c rocks. Thls sect~on was dug along the slope of the bas~n and ~t 1s

probable that leach~ng has taken place along the slope since water docs not accumulate in

4.4 Radiocarbon dating d peat samples

The foremost thing ~n the s ~ d y of any klnd of sediment deposits. for

pal~ewlimat~c Interpretation IS the accurate radiocarbon dat~ng o f the samples Because

of the ubiqu~tou\ distnbut~on of "c, the technlque 1s used extensively for datlng of the

paleo analogues l ~ k e pea. wood, bone. shells, palaeosols, marine scd~rncnts and

dtmo\pherlc CO: trapped in glac~er ice (Bradley. 1985) ~n the late Quaternary studies

The age calculat~on$are b w d on the convent~onal "C half-life (5730f40 years) Th~s

rechnlque can detect the age of sample upto 35 kyr BP For samples older than thls, the

accuracy of the "C can not be obtained due to low emlsslon of the rad~at~on The

rddlccarbon dates on peat samples were obtiuned from the Birbal Sahn~ Lnstltute of

Palacobotany. Luckonw The technlque 1s bnefly descnbed elsewhere (Rajagopalan.

1996)

mln -mu

LY

Figure 4a: Scbanatic diagram of pat d o n from S.ndyn.ll.b bash (bucd on Rajagoprhn, C. 1996)

Table 4 1 shows the l4c ages of peat from dtfferent depths In the two baslns of

Sandynallah and Fig 4 3 lnd~cates the plot of the radiocarbon dates based on Sukumar er

u1. ( 1993) and Rajagopalan. ( 1996)

4.5 Technique lor retrieving pdkn grains from peat samples

The method of retnevlng pollen grams from the sediments 1s explained In Chapter

3, where the same technique IS used for retnevlng pollen grains from the surface peat

\ampler In both SI and SIlI & IIIB sections of the peal core, at each sampl~ng depths two

rlider ( A & B) were prepared for palynolog~cal lnvestlgatlon

Both sl~dea ( A & B) correspond~ng to each depth werr scanned m~croscop~cally

The countlng and ldent~ficatlon of pollen grams for each sl~de was camcd'out by (uslng

obj X40. oc X 10 of the microscope) runnlng 44 l~nes per s l~& at ngular traverses w~th

m Interval of 0 Irnm to avo~d recounting of the pollen grains from the prcv~ous l~ne

Appendlx 3 \how$ some of the plcturer of the pollen p n s that are ntneved and

~dentlfied from the,e peal core samples from Sandynallah The palynomo~hs were

ident~fird wlth the help ot of the Pollen reference collect~on of flora of Nllg~n hills at

Palynology Laboratory. Frrnch Inst~tute Pondlcherry (HIFP). It was also done by

refemng to the Cdtalog of Common Shola and Grassland elements of South Ind~an Hills

(Vaanthy. 1976). w~th the help of Pollen flora of Taiwan (TscngCh~eng ,1972)

Table4.I :Radiocarbon age of SI, SIIl& SllIB peat core sample from Sandynallah region, Nilgiri hills, southern India

Depth Lab. No. Rad~ocarbon Age Recal~brated Age i ~ n cm) (yr B P t la ) (yr B P f l a )

Sandynallah B w n

BS-874 Modem **BS-1083 3831 140 **BS-1085 6591 180 * BS-873 22302 130 * BS-968 2550 t 90 * BS-871 30401 80 * BS-967 4050 + 110 * BS-872 4680t 120 * BS-869 86801 140

* The Rd~ocarbon ddte\ of samples from S1 are based on Sukumar el al . 1993 '* Thc Rad~aarbon dacr ot \amples from Sl l I & l l lB are based on Rajagopalan. 1996

Radlourbon age (in y n BP)

40.

X ? . 0 *

0 MOO loo00 lMOO 2M00

Radiocarbon .o. (in ym BP)

F~gure 3 3 . Plots showlng depth versus radocarbon age from SI and Sll l & [IIB peat cores

Twenty two samples of SI peat core and forty three samples fmm SIII & IIIB

were all processed for palynolog~cal tnvesttgatlon For each sample two sltdes (A & B)

were prepared and both sl~des were counted w~th equal number of ltnes runnlng on both

sl~des, lmspectlve of thelr pollen abundance Therefore twenty two samples of SI peat

core yleldcd 44 sltdcs were counted and 86 sl~des were counted for SIU & IIIB. In SI

peat core all 22 samples have yielded pollen tn amount adequate for stattstrcal analysts.

The total pollen counts range from 372 to 4099 pollen gratns per sample In thts core,

whereas. In SUI & IIIB core although 43 samples were processed and counted for pollen

content. only the top 40 samples out of them have yteldcd pollen In a suffictent amount

The pollen counts In this core ranges from 2 18 to 3 178 pollen grams per sample The last

three samples at the depth of 242 5cm. 247.5 crn and 252 5 cm were poor In pollen grams

wtth 65. 75 and 2 numbers respectively Thus they were not used Another sample at

154 5 cm depth h d s low pollen content of 132 pollen grams In splte of havtng low

pollen content. the sample was tncluded In the pollen dtagram because of ~ f s qualltat~ve

and quantttatlve comspondence wtth ne~ghbonng samples.

In both SI and SIII & IIIB cores correlatton cocffictent values are calculated

between sl~des A & B of each sample and also between vanous samples so as to explun

the varlatlon wtthln and across the samples Rarson's product movement correlatton IS

used for parametric estlmatlon, whlle Spearman's rank comlat~on coeffic~ent IS used for

non-p-tnc esttmatton .

In SI core w ~ t h 22 samples (2 slldes (A&B) per sample) for 44 slldcs, the

Pearon', correlat~on of wlthln sample mean value of 0.98M.02 (11-22) and across

ramples mean value of 0 W . 0 9 (n=924) and Spearman's mean values for samples

w ~ t h In 0 8(k0 05 (n= 22) and across 0 7 2 M 08 (n= 924).

For rest of the analyvs the data used were the pooled data (I e . A & B sl~des were

pooled per each sample) of 22 samples for whlch the Pearson's and Spearman's

correlat~on coefficients values across samples showed values 0.914 08 and 0.6010.08

respec[ively

Slmllarly. ~n SLU & IIIB core with 40 samples (2 slides A & B) per sample) for

80 slides. the Pearson's correlation values for samples wlthln 098M.03 ( n 4 ) and

dcro\\ 0 9610 05 (n= 3 120) and Spearman's mean values for samples w ~ t h In 0 85M04

(n=U)) dnd &ro\s 0 7 4 M 09 (n= 3120)

For re\t of the analys~s the data used were the p l e d data (1.e . A & B sl~des were

pooled per each sample) of 40 samples for whrch the Pcanon's and Spearman's

corrclat~on coeffic~ents values across samples showed 0.95d.04 and 0 . W . 0 8

respect~vely

In both SI and SIII & IIIB cores from Sandynallah basln lnclud~ng all 65 samples,

958 of the semples arc cons~dered well preserved w ~ t h the unldentlfiable grams less than

ILh of the total sum A total of 22395 pollen and >pores were counted from twenty two

samples of SI peat core from Sandynallah bastn. Thts collect~on ytelded 107 types of

pollen taxa lncludtng Cyperaceae and Poaceae Further. 30931 pollen grams and spores

were counted from forty three samples of another peat core In Sandynallah bastn referred

to &. SllI & llIB In this core 117 palynomorph types were tdentlfied tncludrng

Cyperaceae and Poaceae The palynomorphs were grouped Into three dtst~nct categones

ba6ed on thelr llfe forms Arboreal group cons~sts of trees and shrubs, while non-

arboreal group ~ncludes herbs and swampy group consists of aquatic plants growtng In

the water logged and marshy mas These categones exclude Poaceae, Cyperaceae and

spore\ Although Cyperaceae 1s cons~dered as swampy ~t IS excluded from the aquattc

sum In a few cases the fam~ly level tdent~ficatton was also not very preclse, for Instance

for pollen belong~ng to Moraceae or Urtlcaceae

Fig 4 4 and 4 5 shows the pollen dtagrams of the peat cores SI and SIII & IIlB

The pollen d~agram IS obtatned wtth the help of TLIA program (Gnmm. 1991-92) X-

dxla deptcts the relattve abundance of the pollen taxa and Y-axts shows the depth In cm

as well a\ the corresponding ''c radloctrrbon age The counts of Pseudoschlzea, an algal

spore encountered along wtth palynomorphs and the unident~fiable gralns, which could

not be ~denttfied e~ther because of thetr pantal decompostt~on or broken walls are

excluded from the pollen sum. These excluded grams amount to 214 out of 22395

pollen and spores from SI peat core, wh~le 155 out of 30931 from SIII & UIB Hence,

the total number of gralns used for rest of the analysts IS 22181 for Si core and 30776

from Slll & IIIB Behldcs, some of the exotlc specles encountered such as Eucalvprus,

Ptnus und Acrrcru are also excluded from the pollen sum at the very outset.

Foss~l pollen assemblages of the Sandyndlah core arc dominated by Parctcle,

Cyperaceac and pter~dophyt~c spores The pollen types arc ass~gnd to the plant l ife

forms (Table 4 2) such as arboreal pollen group (AP) ~nclucks all species of tras, shrubs

and cllmben from the forests, non-arboreal pollen group (NAP) ~ncludlng herbs and

aquatlcs or swampy arc the plants that arc grown In marshy habitats

The palynolog~cal results are presented on a pollen p a n t a g e diagram (Fig 4.4 &

4 5 ) Four pollen zones are ~dentlfied b u d on the dcndrogram ~ n d ~ c a t d on the nght

hand s~de of the d~agram The dendrogram 1s obtaned by running CONISS from TIL1A

program (Gnmm. 1991-92). CONISS cames out cluster analys~s accodng to the

incremental \urn of square method (also known as Ward's method, mlntmum vanance.

and error sum ot squares) The analys~r IS strat~graph~cally cons t r ind and hence

numrr~cal zondtlon I\ used In zonatlon of the pollen d~agram

4.7 Pollen zonation of SI peat core from S d y r v l l P b

The relatlvc abundance of the pollen taxa ass~gncd to d~sonct physiognom~c

groups In the SI peat core are calculated on the bas~s of total pollen sum (22181) The

result turn\ out as follows Cyperaceae 30%. Poaceac 38%. Aquat~cs 2%. 11% o f Non-

arboreals. 4 8 of Arboreal< wrth IS 5% spores and 0 1% unldent~fied grams Append~x 4

show\ the relat~ve abundance of these groups encountered In the SI peat core from

Sandynallah b a ~ n

PALYNOMORPH TYPES F a d y

Enucac EMcac Emamku?

Ewi='== E- - ETi=-'== F& F W GoDhmvetr Geah.ueac Gorrtwouc tWarrhrovev Ho- b- Iucrmerre IndKuc I- LabUme Lab* Lab* Lambvlnotv L W Lamthcx

LJZhmcr md== Mdaamarar MslammnDaa M~upsmruc Momn M-UrtrYrr *- %=== MY=-= w== w== Olclmc olerac omhhxac RpaJcx Gnmuaw w- Mw=- p-w-K= saopbulruDDlc f!lmh= R m M c u l m

iryp l l A l u d . ~ o ~

Raaculme Rmnrvlruc Rourr Roueuc Rub- Rub- Rnbibxx Rtrbumc Rub- Rubumc Rub- - Rnumc - hdkm2 - Scmpbvl==-= 'Ibcruc

Typhrtre Lnmceu vllaLm;laac

xyndr;ac Tbaeac Sparse %-

Grmlandbab Grmlandherb Gnsslandherb Eccrrmc h b Shola rhrub Grarrlmd herb Gnsslandherb Graulmdhsrb GraaMherb Sbdrrhrub Sbdrahrub SbdrPrc .%la asc Emcoorhrub Sbdrasc sbdawa Grrrslmdhsb SbolrlKc SanpmyM Sbdrok Gnsslandw ~ S w a o p l . h e r b SbdrPrc

Th~s core IS also dlvlded Into 4 toms, based on the nummal zonat~on obmned

from the cluster analys~s, plotted as a dendrogram (Fig 4.4) on the right hand side of the

d~agram

4.7.1 Pollen wne - 4 (Depth: 240-150 cm)

Th~s 1s the lower most zone of the SI core of Sandynallah bas~n. Poaceae and

Rendophyt~c $pores are domlnant at thls level when compared to Cyperaceac 'Th~s zone

IS cla\s~f~ed Into \ub-zones 4a and 4b However, there IS dlscontlnu~ty In the samples

between 227 to I%ms due to lo\\ of samples

4.7.19 Sub-zone 4b (240-227 crn)

W In tht\ sub zone Poaceae dominates w~th a mean of 48%, Yhlle Ptendophytlc

spms are seen wlth a mean of 24% Cyperaceac has a very low value wlth a mean of

6% Aquatic\ vary between 3 to I%, w~th Emcaulon (2%) common than other swampy

elemnt\ such a. Polvgonum Porumo,qrron and Lurembergw that arc found In very low

proponlons Non-arboreal component vanes between 20 to 16% whlch lncludes

Arfemls~o (2-3%). Asteraceac (8-4%), rd Impat~enr (5-38) and Valenana ( 1 % ) Other

non-arboreal elements occur In low proponrons,& lncludy Aplaceae, Gentlanaceae,

Grrunlum. Hvprricwn. Lrucus. L~llaceae. Melastomataceac. Dipsacus. Fahaceae. and

Neonotrs The forest elements such as Elarocarpus. I l u . Mtcrorroprr, S.v:vgrum. Olea,

prrd Mwaceac-Urt~caceac. Evodia. Symplocos. Dodonea. Rubtub Psychorno have very low

yrelds values that together contribute to the arboreal pollen ranglng from 1-21

4.7.1.b Sub-zone 4a (195-150 cm)

Poaceac rcmruns h ~ g h In thls zone w ~ t h a mean of 46% Considerable Increase

occurs In proportion of Cypwraceae as compared to the prcv~ous zone 1.e. from 17% (at

182.5 cm) to 33% (at 162 5 cm), the mean bang 24% Aquatlcs show a mean of 2%

Pol\gonwn IS at I% followed by Erlocaulon and Lcrurembergia towards upper levels of

th~s zone There 1s decrease among non-arboreal compared to prevlous zone wlth a mean

value of 10% Arremlsla. Asteraceae and Impatrens are maintamed In good numbers

Increase In Ap~aceae. Commellnaceae. Gent~anaceae and Xyndaceae IS seen Arboreal

show$ Increa\e from I % (at 192 5 cm) to 5% (at 152.5 cm). Forest spcclcs such as

S~:\gium. Oleu. L1,qlorrum. Moraceac-Urt~caceae. Rhododendron. Mlch#clrcl.

Glorhullon, Srrobrhrhes. Ilex. Psvchorr~o. Svmplocos, and Elaeocarpus, appear In low

numbers at the beg~nnlng of thls z o n ~ f i e n fat 152 5 crn&,Svzygtwn IS represented at 2%

w~th other shola specles In sl~ghtly increased numbers Ptendophyt~c spores dccnase

towards the upper level of th~s zone

4.73 Pdkn Zone - 3 (Depth: 145-90 em)

T h ~ s zone h a mean values 31% and 30% of Poaceae and Cypcraceae

rrjpcct~vely There Ir 1ncred.u In ptendophytlc spores Among quatlcs Enocauhn has

malnta~ned ~ t s presence Luurembergia and Polygonurn decreases towards the upper

depths of thls zone Non-arboreal elements show sl~ght Increase. Arremtsin 1s reduced

Asteraceac (with 10%) shows a sudden peak at 142 5 cm. Impanens occurs ~n high

proponlons Lncrease ~n Ranunculaceae and Xvns IS also seen ~n th~s zone Amongst

arboreal elements Moraceae-Unlcaceae shows a h ~ g h peak at 132.5 cm. Other forest taxa

such us MicMel~a. Elaeocarprcs. S,vryglwn Myrs~naceae and Oleaceac arc present. On M

the whole there IS^ Increase tn the a r b o d component in th~s zone, except for a slight

4.7.3 Pollen zone - 2 (Depth: 85-33 em)

ucl

In t h ~ \ zone also there IS Increase In both Cyperaceae and Poaceae Cyperaceae

ha\ mean of 42% and Poaceae 358 There are two sharp peaks ~n Cyperaceae (at 82 5

cm) w ~ t h 52% and (at 35 5cm) 50%. Poaceae shows correspond~ng decrease at these

depths Pter~dophyt~c spores show sudden decrease from prev~ous zone w ~ t h a mean of

208 to d mean value of 8% ~n the present zone Aquatlcs decrease ~n thls zone show~ng a

mean vdlue of 1 5 % But at 52 5 cm they show 5% which IS due to sharp Increase ~n

Tvph \howlng a peak Aquatlcs are totally absent at depths 72 5 cms and 35.5 cm.

Aquatlcl taxd such as Er~ocuulon. Laurembergro. Polygonwn. Utr~cularro and

Drusera occur ~n very low proponrons In non-arboreal there IS 2% decrease ~n the mean

value from the earl~er zone (I e . I 1% to 9%) There IS decrease ~n Anemrsia. Asteraceac

~n~t la l ly show\ low values, then Increases (2% to 3%) only to fall agun towards the

upper level o f thls zone, Impatlens fluctuates between 1% to 2% . Commeltnaceae

records sl~ght Increase w ~ t h Juncus and Xvns Low valw IS observed for Ranunculaceae

XI rts f 2%) and Juncu~ (2%) are represented In good propontons

The arboreal component lntt~ally ha!, low values In thls zone and there 1s a gradual

Incre&\e towards the h~gher depths of thts zone. The mean value of arboreal element In

tht\ zone I\ 4% Elueocarpus 15 1 6% and I % respect~vely at depths 92.5 cm and 72.5 cm

gradually showlng decreae towards the higher depths Mlchplta ~ncreases to 2% at 35.5

cm Other forest taxa l ~ k e Ilex. Myrslnaceae, Glochldron, Oleaceae, Rubus, Symplocos,

u P~peraceae. Mordceae-Urtlcdceae. Oleaceae, Svzvgium. Berbcndacw and Dodolea

conlr~bute to the Increue of arboreal elements In thts zone The ptendophytes are less In

thlb zone

4.7.4 Pollen zone - 1 (Depth: 30-5cm)

The Podceae and Cyperaceae have mean values of 36% and 33% respecttvely

Aquattcs show a mean value of 2% Enocaulon. Tvpha, tovrembergta and Polvgonum

M found In good numbers Other aquattc taxa such as Potamogeton. Utnculonu arc also

present The spores are sl~ghtly more abundant, better wtth a mean o f about 9% than the

prevlouq zone wlth 8%

Non-arboreal elements Increase to a mean value of 14% Anemls~a agiun

lncred\er upto 1%. dccompanted by Asteraceae to ?I. and Impoterns upto 3% Juncus

and Xvrts also represent about 1% Other herbaceous elements such as Jwticia,

Gentianaceoe. Osbeckia Ranunculaceae, Valeriana, Olhnlandib, Brassicaceae.

Campanulaceae. Commeli~ceae, Amarunthnceae-Chenopodloceae, Amaryllidaceae and

Lubiutae all contribute to the increase of non-arboreal elements to a mean of 14%

Arboreal components also show ~ncreax with a mean value of 6%. Mahonlo,

Elaeocarpus. Moraceue~Unicaceae and Rapanea have values more than I % . The other

arbowdl that are fa~rly represented are Ilex. Microrrop~s. Glochtdion, Rhodomyrtus,

Sv:vglwn. Oleu. Ruhus. Srrohrlanthes, Mich)elra. Piperaceae, Svmplocos, Eutya and

4.8 Pdlen zonation or SIII & IIlB peat core from Sandynalloh

The totdl number of grams counted from th~s core is 30931 from 43 samples But

the countr ured for data analyses u e 30776 from 40 samples The relative abundance of

the pollen taxa dssigned to distinct physiognom~c groups in the SIII & IW peat core arc

calculared trom the total pollen sum (30776). They arc. Cyperaceac 4%. Poaceae 52%,

Aquat~cs 2%. 19% of Non-arboreal. 4% of Arboreal with 18 1 spoms and 02%

Un~dentlfied grams Appendix 5 shows the relative abundance of these groups

encountered in the SIIl & IIIB peat cores from Sandynallah bas~n.

Th~a core la also dlvlded lnto 4 zones. baed on the numerical zonatlon obmned

from the cluster analysis, plotted ds a dendrogram (Fig 4.5) on the nght hand slde of the

dlagram

4.8.1 Polkn Zone - 4 (Depth: 240-195 cm)

Thl\ I\ the lower most zone of the SlIl & IIIB core Poaceae and spores show

high percentage al this level Sporad~c d~str~but~on of Cyperaceae can be observed at th~s

level Thls zone Ir d ~ v ~ d e d lnto 2 \ub zones 4a and 4b

1.8.1.11 Sub-zone 4b (Depth: 240-210 cm)

B- At t h ~ \ zone Poaceae I\ most domlnantqpresented w ~ t h a mean value of 65%

followed by Spore\ w ~ t h 17%. non-arboreal w ~ t h 16% Cyperaceae IS very sporad~cally

dl\tnbuted Aquatic, are dl\o very low wlth a mean value o f 1%,@e to scanty

appearance ol Errrnuulon and Polc~onum Non-arboreal component has a mean value

of 16%

The domlnant herbaceous taxa IS Anemls~a w ~ t h h ~ g h p m p m o n of 7%.

Asteraceae ( 1 %-3%) and Ranunculaceae ( 4%) also show very h ~ g h pmponlon. besides

&A Aplaceae. Vulrrrunu (1%). Lab~atae (1%) and Gcranrum (1%) are recorded In good

numbers at 132 5 cm. 222 5 cm and 1 I I 5 cm depths rcspect~vely Other herbaceous taxa

such as Gent~anaceac, Geran~wn. Melastomataceae. Xyns, Pnmulaceae. Brasslcaceac and

D~psacus also. but In very low values

Arboreal component IS very sporadically dlstnbuted. The mean values ue less

than 1% (0 8%) Tree taxa such as Elaeocarpus. hphnrphvl lvm Glochidion,

Rhodomvnus. Psvchotria. Svzyg~um, P~peraceae, Eutya, Rubus. Strob~lanthes, Mahonu,

are present but very poorly represented Spores show Increase from 11% to 26% with a

mean value of 17% Aquat~cs and arboreal arc totally absent at 237.5 cm depth.

4.8.1.b Sub-me 4a (DepIh: 210-195 cm)

At th~s zone Poaceae 1s h~gh, havlng a mean value of 61% and Cyperaceae at

0 8 4 mean value Aquatlcs and arboreal st111 low at 0 6% and 0 8% respcct~vely Non-

arboreal at 15% mean and spores Increase to 22% mean. Swampy taxa such as

Erlocaulon. Laurembrrgra. Polvgonum. Utr~cularra show very sporadic dstnbuuon at

th~s level At 205 5 cm aquatlcs are absent Amongst non-arboreal Anemula shows

fluctuat~ons between 2% to 5% at thls zone Aplaceae IS reduced In cornpanson w ~ t h the

earlier zone Asteraceae and Ranunculaceac vary between 2% to 4%. Although

Ranunculaceae 1s low at 205 5 cm depth. ~t increases again towards the upper level o f th~s

zone Geranrwn IS also represented In good proporrlon and shows values between 1% to

2% and decrease towards the upper level There IS good reprcsentatlon of Lab~atae along

w ~ t h Juncus and Pnmulaceae In the upper level of th~s zone. Total absence of arboreal

elements are obberved at 208 5 cm and 202 5cm But towards the upper level of this zone

I e . at 199 5 cm, slowly the appearance of the tne taxa such as Elaeocarpus.

Rhododendron. Daphnrphvllum, Glochrdlon. Mrchelra, Svzvgrwn. Rhodomyflus and

Rubus are observed

4.8.2 Pollen zone - 3 (Depth: 195-155 cm)

Poaceae fluctuates between 35% and 65% w ~ t h a mean value of 52%. Cyperaceae

values sl~ghtly lncrcase from I % to 7%. w ~ t h a mean value of 2.5%. Aquatlcs also

Increase 10 a mean value of 1 5% The Increase In aquatrcs IS seen towards the upper

levels of th~s zone Errocaulon 1s present at the lower level, In very low proportions and

then show5 Increase at the upper three levels 162 5 cm. 159.5 cm and IS6 5 cm to 2.4%,

3 2% and 2 7% respect~vely Other aquatlc taxa appearing along wtth Errocaulon are

Polvgala. M\rrr~phvllum, und Utrrculurru

The non-arboreal elements also show Increase In th~s zone w ~ t h a mean value of

19% The dom~nant taxa are Arremrsra, Asteraceae, Geran~aceae. Ranunculaceae,

R~mulaceae. L;lb~atae and Lrllaceae Asteraceae 15 domrnant, the proportion of whlch

fluctuates from 2 4% to 6 9% w ~ t h a mean value of 4.8% I t reduces to about 2 4% at

174.5 cm depth. Artemrsra 1s ~nl t~a l ly . low at 18, Increases to 596, goes down to 3%

wh~ch again \bows Increase to 8% towards the upper level o f th~s zone. Ropon~on of

Apraceae la very low ~ n ~ t ~ a l l y and then Increases to 2.44 In the upper levels of thrs zone

Ranunculaceae fluctuates between 1% to 4% Gerun~wn 1s ~n~ t la l l y at 2% hen shows a

d ~ p In the m~ddle agaln reaches 2% towards the top level Lab~atae and Juncus are low

In the beglnnlng and then show gradual Increase hmulaceac 1s h~gh ~n the beginning

and gradually decreases towards the upper level. Palynomorphs such as Valeruvur.

Rub~aceac. L~llaceac are found to be In good numbers towards the upper level of thls

zone Rublaceac 1s found to be ~ncreased to 2% towards the upper level of t h ~ s zone

Other palynomorphs such as Xvns, Caryophyllaceac, Commellnaceae, Melastomataceae

and Impatlens are also seen. but are very few ~n numbers. But most of these are present

In good numbers at 156 5 cm depth

Arboreal IS st111 found to be very low ln~ttally even at t h ~ s level. Gradual

mcrease In thew relat~ve abundance 1s observed towards the upper depths of thls zone

Arboreal taxa such a\ Svmplocos, Svzvpm. Daphniphvllwn, Mtckl ia . Glochrdion,

Dodonaea. Rubus. R1u)dodendron. Elaeocarpus, Eupa and Olea, though represented are

very aporadlcally d~str~buted

But at 190 5 cm there 1s total absence of arboreal as ~ndlcated. And at 171 5 crn

depth Moraceae-Unlcaceae IS lnd~cated at 3 7% and Elaeocarpiu lnltlally low has a value

of 1 4% at 162 5 crn depth and at 159 5 cm 1s prominent Shola components such as Ilex.

S a r ~ o c c w . Strobrlanthes. Mahonia and Daphnrphvllwn, are Indicated at 156.5 cm

depth At t h ~ s depth Svzygrm 1s at 1% and Oleaceac at 1.5% with other taxa such as

Lasmnthus. Psvchotrra. Melicope. Gordonra, Rapanea and Microtropis are represented

In qultc good numbers The spores are found to be fluctuat~ng between 1 1 % and 30?&

wsth a mean value remalnlng same as the earl~er zone at 22%

4.8.3 Polkn Zone - 2 (Depth: 159-180 em)

Poaceae ~n th~s zone shows decrease when compared to the earlrer zone w ~ t h a

mean value from 52% to 49%. I t fluctuates between the h~ghcst value of 59% to the

lowest value of 33% The Cypcraceac proportion has ~ncreascd to 4% o f the mean value

when compared w ~ t h 2.5% of the earlier zone. The variations observed from InQvidual

depths at th~s zone arc found to be betwczn 1% to 6%. Aquatics here are found to be

doubled from earl~er zone w ~ t h a mean of 1 5% to 3% than In the present zone Total

dbsence of aquatlcs 15 seen at 157 5 cm depth. Aquat~c taxa such as Enocaulon.

Polvgah. Polvgonum, Droscra. Tvpha and Utricularra are ~n~ t ia l l y found In very low

proportions and they lncreax gradually towards the h~gher depths of th~s zone

Non-arhorealJfluctuate between 10 to 25% at th~s zone They have a mean value

of 20% a1 th~b zone The proportions of Artcmlsiu. Ap~aceae, Asteraceae. Geranium and

Ranunculaceae are found to be h ~ g h lnltlally and then gradually drops towards the upper

level of th~s zone Impuricm now starts appearing and slowly Increases towards the

upper level ot t h ~ r zone Valerianu. Xvris. Kubiaceae, L~liaccae. Juncur appear ~n good

numbers ~n between the lower and upper levels of this zone hmulaceae also shows

good represcntatlon lnit~ally decreases and then found to be absent towards the upper

level of thts zone Other herbaceous palynornorphs such as Labiatae (Micromeria.

h u m ) . Caryophyllaceac. Carnpanulaceae. Pcdicularis, Melastomataceae ( O s b e c b ) .

Jrcsncru. Hvpericum. Amaranthacetie-Chenopod~aceae are represented in very low

proponlona at thls zone

lin ArboreaJshow Increase w~th a mean of 4% from tk earller zone to a mean of 6%

~n th~s zone The proponlons vary from 2% to 8% Shola elements such as Syzygiwn,

Elaeocurpus. Glochrdron, Rapanea, Olea. Psvchotrra, Rubus. Rhodornyrtus, Gaulthcna.

Glorhrdron. Svmplocos. L~gustrurn. Plperaceae and Nothapodvtes are dlstnbuted

sporad~cally In the lnit~al depths of thls zone and later on show Increase In thetr

proponronq towards the upper levels of t h ~ s zone Moraceae-Un~caceae has gone upto

2% at 147 5 cm depth. Myrs~naceae goes upto 3% at 122 5 cm. Elaeocarpus 1s found to

be 1 8% dt 142 5 cm and 137,s cm. whlch reduces agacn from 127.5 cm onwards. Other

Imponant arboreal palynornorphs such as Melrcope. Sarcoccoca, Vrburnwn and

Muhonru are also represented towards the upper level of thts zone. Spores are found to

be decreasing towards the upper level of th~s zone wlth a mean value of 18% The

proponlon+ of palynomorphs at lnd~v~dual depths fluctuate between 40% to 10%

1.8.4 Pollen Zone - 1 (Depth: 95 to 15 cm)

In th~r zone both Poaceae and Cyperaceae have shown constderable Increase In

therr proponronr Poaceae goes to 55% mean from 4 9 6 of the earher zone. Cyperaceae

has shown !ncrease to a mean value of 18% from 4% mean value of the earl~er zone

Aquatlcs have reduced to 2% mean value Gradual lncrcase rn Eriocaulon 1s observed

Very sporadic d~rtrrbut~on of Polvgonurn. Tvpha. Utrrculana and Luurembergra arc

Non-arbore show cons~dcroblc decrease tn the p r o p o n when compared wlth 9 mnc -2, show~ng a mean value of 10% Asteraceae. Anemisia are found to be low tn the

beglnn~ng of thts zone, but gradually rncrease to more than 1% and 2% respectively.

Importens IS high tn~t~al ly, then decreases to 0.8% and agiun Increases to 1% towards the

uppn level Xvrrs and Valerrana rhow tncrease of 2 4% and 1 % at 72.5 cm depth 0th-

hehamus palynomorphs such as Mtcromena. Genttanaceac. Rubtaceae (Neonotis),

LJII-. Juncus. Commel~naceae. Geranrum. Caryophyllaceae. Campanulaccae,

Crornlarra. Pedicularrs. kucas. Melastornataceae (Osbeck~a). Pnmulaceac and Tragia

arc ieprrsented In very low numbers.

Arboreal also shows decrease at th~s zone to a mean value o f 5% Some of the

domrnant tree taxa appearing In good propontons at thts zone are ELtcocarpw.

M ~ l t a . Sv:v~rum, Moraceae-Unrcaceae, and Svmplocos. Svzvgrum IS I 7% at 37 5

cm d Mrc@11a show5 gradual Increase and reaches upto 1% at 37 5 cm Symplocos IS

also observed to be present In good numben Other shola elements such as Psvchotrra,

R h . Vrhurnum. Mah~nia. Glochuiron. Rapanra, Lrgustrwn. Oba. Rhodomynus.

Nodulpodvres. Ilcr. ~odon%a. Eurvu and Tanllus are represented very sporadrcally In thts A

unc. Spores In th~s zone have decreased to I I % mean from 18% mean of the earller

zone.

4.9 D i i o n of palynological results

The vegetatcon and cllmat~c changes of the late Quaternary are recorded In the

peat deposlts of trop~cal montane reglon (21800 m a.s.1) of Western Ghats, southern

Ind~a -9arller stud~es have documented these changes based on pollen records

(Vasdnthy. 1988. Sutra. 1997) and 8 " ~ records (Sukumar et al. 1993. Rajagopaln ct 0 1 .

1997) The peat ramples used for the palynolog~cal ~nvestlgatlon arc same as the ones

that are u\ed for the study of dl'c records More relevant to the purpose of h s study IS

obsewat~on of the changes In pollen composltlon of the vegetation In peat deposrts

spannlng the late Quaternary perlod

In the montane shola foresta at the h~gher alt~tudes of southern Ind~a the most

domlnan~ fam~ly 1s Lauraceae represented by 19 3% of specles (Sukumar eta1 1995)

But I t I\ unfortunate that these pollen gralns are not preserved In the peat depos~ts. as

Lauraceae pollen gralns are vlnually devo~d of conspicuous of excne and get destroyed

dunng foss~l~zat~on and also read~ly damaged by acetolys~s (Van der Menve, et a l .

19901

The \tud~es have documented that the slgnaturcs of past vegetatlon from the

dcpos~ts spannlng 40 kyr have shown considerable sh~fts In the vegetatlon patterns In

altcnng the montane forests In the h~gher altitudes The palynolog~cal lnvest1gatlons

camed OUI at Kakathope (Gupta. 197 1 ) revealed 4 stages of changes Between 40 kyr

BP to 35 kyr BP the vegetatlon ch~efly consisted of herbs w ~ t h co-dom~nant shrubs and

few trees Around 35 kyr BP to 15 kyr BP there was a sh~ft In vegetahon through

gradual lnvaslon of shrubs Into the open land w~th sporadic herbs forming a thlcket.

From I5 kyr BP to 7 kyr BP establ~shmcnt of forests have been lndlcated by ~nc- In

the forest taxa. T h ~ s sh~ft could not be dtrectly due to cl~rnate alone but also due to

human lnterventlon In the area. The Colgran profile revealed that between 12 kyr BP to

? kyr BP the expanston of forests wen observed Decline of sholas were raordtd only

at 2 kyr BP unllke Kakathope at 7 kyr BP. (Gupta and Rasad, 1985). The Pykara profile

(Menon. 1968) reflects predomlnancc of grasses Wlth the esttmated date of - 5 Kyr BP

the Pykara profile could be correlated w~th the t o m o s t part of Kakathope tndlcaung

raptd \avannlzatlon due to anthropogen~c effects Sandynallah core datlng back to 30

Kyr BP (Vasanthy 1988) shows overall predornlnance of grasses. Asteraceae and other

herbs Another new pollen profile from Sandynallah datlng back to 35 Kyr B P (Sutra

1997) also ~ndlcates the dorn~nrnce of gra\e\ and swamp plants Glacial penod was

domlnaled by C4 grasec. Artrm~sru and Aptaceae The upper pan of core spannlng 5 kyr

shows mcna\e of Mtchclra at 3 8 Kyr BP (Sutra. 1997).

The results on the pollen Xquence from two cons from Sandynallah arc

dlwussed below

The two corer referred to a\ SI and SIII & IlIB cores analyzed from Sandynallah

basin for pollen Investlgdtlon In the present study date back to d~fferent tlme penod

I S1 core date back to about 9.5 Kyr BP

2 SIII & IIIB cores span between 17 to 2 Kyr BP

So broadly the pollen profiles from two cores from Sandynallah cover the

vegetat~onal and c l ~ m a t ~ c changes from Last Glacral Maxrmum to Late Holocene penod.

4.10 Inferences from pollen analyses spanning Last Glacial Maximum to Late

Holocene period (I7 kyr BP to Resent)

Around the perrod of LGM the h~gh percentage of grasses along w ~ t h herbaceous

elements such i& Artrrnista. Asteraceae, and Ranunculaceae wrth Aptaceae were

domrnant wh~ch ~ndrcates the gradual sh~ft towards hum~d cond~trons Scanty drstnbutron

of wee taxa and h ~ g h percentage of spores would expla~n the avarlab~lity of humid

condrt~ons and slow expansion of the forests A decrease ~n grasses was observed

toward\ I2 5 Kyr B P to 10 Kyr B P and Increase in arboreal pollen. whrch explains the

expanston of forests towards the early Holocene Thrs can be broadiy compared wrth the

pollen profiles of Kakathope (Gupta 1971) and Colgra~n (Gupta and Prasad. 1985)

Thrs gradual \h~ t t towards the Increase ~n arboreal pollen can be compand to the other

studres such as pollen records an a lake of nonh western Indra (S~ngh at 0 1 . 1990) and

fluv~al depos~ts ~n central Indra (Wrllrarns and Clarke, 1984).

The \tudy ra also ~n agreement wrth the pollen sequence of Burund~ from trop~cal

Afnca that rnd~cated the forest vcgetatlon wrth today's florrst~c composttlon appeared at

around 13 Kyr BP (Bonnefille and Rrollet, 1988) suggesting humd condrtrons. The hrgh

percentage of arboreal extends up to 9 4 Kyr rn Sln core, at 122.5 cm and contrnucs to k

so up to 6 Kyr B.P at 1 1 1.5 cm rn SIIl core. But ~n SI core at about 8.5 Kyr BP,

partrcularly at depth 236.5 cm the arboreal arr found to k quite low wh~ch IS indicated at

4b zone of SI pollen dragram (Fig 4 4)

However. other elements \uch as aquatics, non-arboreal and spores an found to

be hrgher but Cyperaceae remarntlow In SI core the cont~nurty between -8.5 Kyr B P

and 4 Kyr B P IS lost due to loss of samples durlng collectron. Hence thrs penod has to

be Interpreted by comparing wrth the SIll core The penod between 5 Kyr BP to 2 Kyr

BP shows there IS a consrderable decrease in arboreal 5% to 2% from S m core. Low

percentage ot arboreal IS also observed ~n SI core. Poaceae and Cyperaceae show

cons~derable Increase In both the cores along wrth decrease ~n aquatics, herbs and spores

Sharp increase In g r w md xdge pollen ~ndlcated the andrty dunng this penod, Increase

~n Cyperaceae pollen. dlthough a swampy plant, the spread of these taxa could be of Ca

tY F=

Sandynallah core\ also indlcate Increaye In arboreal pollen from -2.5 Kyr B P

onwards. There IS Increase rn spores, non-arboreal pollen and aquatrcs. Although

Poaceac and Cyperaceae arc marntmncd at h~gh percentage, the forest taxa indicated ~n

good proponlon are Elu~ocarpur. Mlchaelw, Syzvgiwn. Myrslnaceae. Berbendaceae and

Moraceae-Urtrcaceae. Along w~th these other tree taxa such as Iiex. Rhodomvrtus. Olea.

Viburnum. Gioth~dton are alao encountend In very low numbers The herbaceous

elements that have contributed towards the Increase of non-arboreal pollen are Imput~ens.

Xyrts. Gent~imaceae. Juncaceae. and Ltl~aceae along with Anernrsur and Astcraceae in

good proponlons. Enocaulon. Tvpha. Luurembergla. Poivgonum are the maln aquatlcs

contr~butlng to the~r ~ncrease T h ~ s perlod would ~nd~cate the cooler and more hurn~d

cl~mate following a dry per~od between 5Kyr to 3Kyr BP T h ~ s ep~sode is also tnd~cated

from other cores (Vasanthy. 1988. Sutra, 1997). Iiex IS very sensltlve to very low wlntcr

lemperature and a r~d condlt~ons It requlres atmospheric hum~dlty and so11 molsture and

can w~thstand lowest summer temperatures (Iverson, 1944; Martin. 1977). The

establishment of some of these core shola specles could be suggestwe of cooler and more

humrd cllmatc In the montane reglon slnce - 2.5 Kyr BP Although human disturbance

could have occurred around 2 Kyr BP, as the pollen record lacks ev~dence of dlrect

anthropogen~c indicators. I t Is an unl~kely explanat~on for the changes reglsured ~n the

pollen data. T h ~ s may also colnc~de wlth the ev~dence obtaned from Eth~op~a

(Bonnefille dnd Mohammed. 1994) whlch ~ndlcates the upward regrowth of the forest

~ndlcat~ve of the recent warming around 3 kyr BP

4.1 1 Detrended correspondence analysis

The composluon of the vegetdtlon cornmunlty ~n the past represented In the

surface of the sample, was compared w~th the composltron of all other samples to

determlne the degree of slm~lur~ty among samples from d~fferent time scales In SI and

SIlI cores Samples were arranged In ecological space using the standard ecolog~cal

method of ordlnat~on called Detrended correspondence analys~s (Gauch, 1982) Here the

compos~t~onal dtsb~rn~lar~r~es between samples are calculated to determ~ne the underlying

gradtents lnfluenc~ng the data. The tcchn~que 1s bnefly described In the earl~er chapter on

surface pollen studles

The numerical analysts prov~des a means of detectlng the structure or paaern In

thc data The Detrended Correspondence Analysts was performed by uslng TILIA

program (Gnrnrn. 1991-92) uslng two axes to arrange all the samples acconhng to thetr

dtnatton scores so ar to reflect the gradients on SI and SIII & IIIB cores The analysts

was carned out separately on both the cores In SI core a matnx of 107 vanables and 22

sampks and I n SIII & IIIB core matnx of 116 vanables and 40 samples were used for

d n a t t o n The percentage rnatnx was used for the analysls and not the counts. F I ~ 4.6

~nd~caics that pollen count\ and pollen percentage are htghly correlated (r = 0.97, n=lM).

Thc rcgre\\lon of DCA values of axlr I of pollen percentage plotted In Fig 4.6 shows

t b they h~ghly correlate

Ordinauon scores on four axes arc obtalned for both samples and the vanables

scpMely The ordtnatton xores of the samples for both SI and SIII & IIIB (F~gs 4 7 &

Fig 4.8) lndlcdte \cores plotted on axls I and axta 2 In the DCA plot of (Fig 4.7) SI

wmp* cores. I t IS observed that 22 samples from t h m dlstlnct clusten can be broadly

p u p d under d~fferent tlme scales such as. penod around 9.5 kyr B P, around 4 to 2.3

k y BP and pertod < I kyr BP or present However, of these 22 sample scores two to

three =ore\ are outl~er\ that Ile considerably away from these groups. In SI DCA plot all

the 22 sample\. more or leas get clustered sequent~ally In the order of thetr depths The

Ploc of ordlnat~on scores (Fig 4 8) plotted w~th SIIl & IIIB samples also can be broadly

Figure 4.6: Sandynallah - I peat core Pollen Counts vs Percentage

Axis 1 (count) Eigen value - 0.09

Figure 4.7: Plot of DCA scores of SI samples from Sandynallah basin

0 8-

0 142 51

o, Mid-Holocene 3 -

I , / /

Early-Holocene

AXIS 1 Eigen value = 0 11

Figure 4.8:Plot of DCA socres of SIll& SIIlB samples from Sandynallah basin

grouped under d~fterent tlme \tale\ They form 4 d~s t~nc t groups - the penod < 16kyr

B P. 12- 16 Ky r B P. 17-9 Ky r BP and 4Kyr B P to pre\ent In t h ~ s plot alro there arr two

ro three ourller\ that dre away from the\e groups L n l ~ k e SI core here the samples are not

clu\tered \equent~ally In the order ot therr depth but roughly they are In the sequence w ~ t h

(he mlxrurer ot rdmple\ here and there amongst there four groups T h ~ s could be

probably due ro the \ ~ m ~ l a r l t ~ e \ In the t d x ~ that co-occur w ~ t h the auoc~ated specles

Some of the\e \ampler are more \ ~ m ~ l a r to other samples than w ~ t h therr subsequent

\ ~mp le r In term\ o f specie\ compo\luon

Thl\ technrque theretore prov~dea a quantltar~ve mean5 o f l den t~ f y~ng the past

communlrle\ that have per\l\ted durrng the late quaternary per~od

Theretcrrr ~t I\ clear from the ordrndrlon rechnrque thdt the p a t cores from SI.

S l l l & Ill0 from Sdndyndllah b a r ~ n de \c r l k \ vegetation changes and c l ~ m d t ~ c changes

thdt habe been rb~denced from the pollen analy\l\. * h~ch also deccrlbe the gradual sh~f t

In the vegetation and rvolutlon ot the montane fore\[ dur~ng Holocene perrod The

numerrcal dnalyrr\ l ~ k e DCA ~ n d clurler andlysls w ~ t h fossll pollen spectra quant~tdt~vely

\~renglhen the Inference obra~ned trom pollen ev~dence and support the conclus~on o f

other r tud~e\

4.12 Correlations between fossil pollen cpectra-modern vegetation-surface pollen

assemblage.

The to\\ i l pollen \pectra ohtdlned from the t ~ o cores o f S l and SIII & IIIB corer

from Sdndynallah harln were \uhjected to further rlatl\tlcal analysls The parametric

dppro~ch ot Pear\on'\ product moment correlation coetflcient and the non-parametric

approdch ot Sprdrnlan \ rank correldtlon method wd\ method wah employed to observe

the \lgn~ticdnt changer between the to\\i l pollen rpectra wlth vegetation compo\itlon and

the \urface pollen a \ remhl~ge

The ahundancc d.11~ mdrrlcr5 from vegetatlon. surface pollen and fo.;cil pollen

rpecrrd were used tor the calculation A l l the taxa in both rnatrlces were considered. ac

thr prcrence or ah\ence 01 part~cular tdxd In e~ther o f these rnatnces whlch 15 a very

Impondni inlormditon ~ . r for a\ the compdrdtlve approach o f modern analogue5 and fos\ll

d\*enihlage. arc ~ o n \ ~ d e r e d

In vegetatlon niJtrix grd\\ rpecler m d \edge \pecle\ were considered dt family

level tor the ~ n d l y \ l \ Thl \ wd\ done In order to maintain the u n ~ f o r m ~ t y between pollen

~ \ \ e m h l ~ g e \ and plant \peeler J\ the pollen o f Poaceae and Cyperaceae can not be

dl\tingul\hed to generic or rpecler level from palynolog~cal invebtlgatlon

Fig 4 9 and 4 10 ~ndicdte both Pedr\on'r parametric and Spedrman's non-

ParanletriL ~ o r i e l ~ l i ~ n c o e t l i ~ ~ r n t \slur\ plotted Igdln\t erch depth o f both SI and Sll l

SandynallaM vs Vegetation

F~gure 3.9: Plots depth and correlation coefficient values of S I peat samples versus grassland and peatbog vegetation from Sandynallah basin

Sandynallah-Ill 6 Ill8 vs Vegetation

Figure 3.10: Plots of depth and correlation coeffic~ent values of SIll & IllB samples versus grassland and peatbog vegetation from Sandynallah basin

and IIIB peat cores from Sandynallah basin with the grassland and peat bog vegetation

from the same bog. The results are discussed below.

S I peat core samples are correlated with the modem vegetation with value of

n= 19 1. Fig 4.9 indicates correlation coefficient values for SI samples with grassland and

peat bog vegetation from Sandynallah basin. In terms of Pearson's values the grassland

type with in site acrosr the depth are between 0.88 t 0 03 and 0.50 i 0.06. The highest

value (0.89) with Sandynallah grassland is indicated at the depth of 152.5 cm (around 2.3

kyr BP) and the lowc.rt value la observed at 35.5 cm (0.53) that dates back to very recent

penod In terms of Spearman'\ value the h~ghest is at 35.5 cm (0 77) and the lowest

(0 50) at 162.5 cm (around 2 5 kyr BP) penod

Sandynallah peat bog In terms of Pearson's values at 35.5 cm has (0 87), wh~le at

236.5 cm (0.58) H~ghcst value is observed at 52.5 cm (0 91). The mean values of sholas

across the depth 1s between 0 5 3 d 20 and 0 2 8 d 16

Spearman's mean comlat~on values of grassland types across SI depth shows

maximum of 0.75iO.02 and minimum of 0.49j3.02. Peat bog mean values arc also

sim~lar to grasslands (0 75d.04). whereas the minimum value IS 0.72tO.M In terms of

Spearman's cornlation coefficient, both grasslands and peat bogs have values wittun the

same range, while in Pearson's, they show vanation. When there is low value in

grassland, high value 1s observed in peat bog and vice versa. This could be due to the

vegetation composirion of grassland and peat bog types

Fig 4.10 lnd~cates the depth and correlat~on values from SIII & IIiB samples with

grassland and peat bop vegetarlon ~n Sandynallah basln (11-198) In terms of Pearson's

values. the grasslands have a maxlmum value of 0.92iO 04 and the mlnlmum value being

0.574.02. The peat bog maxlmum values arc 0.65dl 13 and mlntmum 0 .344 09 The

h~ghest Pearson's value w ~ t h Sandynallah grassland 1s 0 93 around 2 6 kyr BP and the

lowest value 1s at 0 57 at > I I kyr BP. In th~s case the values w~th in Sandynallah

grasslands and peat bogs. grasslands seem to be havlng h~gher values across the depth

compared to peat bogs. The mean values of sholas across the depth are between

0 5 7 ~ 1 0 ~ n d O 3 5 4 11

In terms of Spearman's comlat~on caf f ic~ent of SII l & IIJB core, the mean

values of grasslands are between 0 82iO.03 and 0.474.06 and peat bogs have 0 824.06

and 0 524.04. Sandynallah grassland has Spearman's values between 0 85 and 0.40 and

Sandynallah peat bop IS between 085 and 0 57 Sholas have mean values between

0 78iO 02 and 0 45iO.03

In both SI and SI l I & IIIB cores they dlffer In correlat~ons between modem day

grassland and peat bog In core SI the peat bog vegetatlon seem to have h ~ g h correlar~on

valuca than grassland vegetatlon w ~ t h mcan values of pcat bogs across depths belng

0.824 10 and grasslands wlth a mean of 0 76t0 10. In SIII & IIIB core grasslands seem

to have h ~ g h mean values across the depths of 0 864.06 w ~ t h mean peat bog values of

0 5953 09.

4.12.1 Comlstions of S1 and SIII & IlIB peat c w g with surface polka

Fig 4.1 1 and 4.12 deprcu the SI and SIII & IIIB samples cornlated wrth surface

samples of Sandynallah. Bangrtappal and Varahapallam basrns.

In terms of Pearson's comlatron values S1 core samples across the depth with

modern pollen from Sandynallah surface sample has a mean value (nr133) of 0.90t0.06,

whrle Varahapallam has 0 77iO 02 and Bangitappal being 0 . 7 W 12.

In terms of Spearman's comlatron values all the three srtcs have mean values

(n=133) rn the rame range. Sandynallah berng 0.54iO.l I, Varahapallam 0.54iO 07 and

Bangrtappal has mean value of 055iO.08 It IS clearly observed In the plot that

Bangrtappal and Varahapallam curves are overlard but Sandynallah lies above these two

curves

In terms of Pearson's values SIII & RIB samples across depth. wrth

Varahapallam surface samples rndrcate the value (n=136) of 0.94iO.05, whereas

Bangnappal shows 0.93iO 06 and Sandynallah has 0.89d.06 In terns of Spearman's

values. Sandynallah has a mean value of 0.54iO.09, Bangrtappal 0.54iO.07 and

Varahapallam 0 54iO.07.

Figure 4.1 1 : Plots of depth and comlation coefficient values of SI peat core samples versus surface peat samples of Sandynallah, Bangitappal and Varahapallam basins

0 0 . - -. -. . . -- -- . . -- - .-. - - 10 ea 110 lea 210 280

Dsn (om) - t ~ . - * . . ~ - A - - V . n h q Y v n

Figure 4.12 : Plots of depth versus and correlation coefficient values of SIII & IIIB peat core samples versus surface peat samples of Sandynallah, Bangitappal and Varahapailam basins.

4.13 Discussion

The d~fferences In the comlat~on values of vegetatlon and fossil spectra observed

In both cores could be probably due to the local site variation, molsture condit~ons and

also to some extent due to the vegetatlon composltlon present dunng sarnpllng.

However, the fossrl pollen spectra correlated against surface pollen, $e mean

comlat~ons across assemblage is high compared

to the other two sltes. . Thenfore by and

large the modem pollen assemblage rcflccythe surrounding vegetation pattern. Hence i

th~s study of plant abundance and modem pollen assemblage in a Oven area w& an

essentlal step to Interpret the foss~l pollen spectra used for nconstructlng the past