Pollen morphology of Himalayan Pinus and Quercus and its importance in palynological studies in Himalayan area

ELSEVIER

Reviewof Palaeobotanyand Palynology91 (1996) 317-329

REVIEW OF PALAEOBOTANY AND PALYNOLOGY

Pollen morphology of Himalayan Pinus and Quercus and its importance in palynological studies in Himalayan area Takeshi Nakagawa a, Yoshinori Yasuda h, Hideo Tabata c a Department of Geology and Mineralogy, Faculty of Science, Kyoto University, Kyoto 606-01, Japan b International Research Centerfor Japanese Studies, Kyoto 610-11, Japan c Centerfor Ecological Research, Kyoto University, Kyoto 606-01, Japan Received 13 July 1994; revised and accepted 19 May 1995

Abstract

Modern pollen grains of Himalayan Pinus (P. roxburghii and P. wallichiana) and Quercus (Q semecarpifolia, Q. incana, Q. lanuginosa, and Q. glauca) were examined by scanning electron microscopy (SEM) in an attempt to identify fossil pollen grains of Himalayan Pinus and Quercus species. The exine sculpture of P. roxburghii is clearly rugutate and that of P. wallichiana is smooth or slightly rugulate. The exine sculpture of Q. semecarpifolia is scabrate and that of Q. glauca is microscabrate whereas other Quercus species examined have a microverrucate-scabrate sculpture on the pollen exine. These differences serve to identify fossil pollen grains of Pinus and some Quercus species, each of which is distributed in a specific climatic area. Pollen analyses on sediment samples obtained from the Kathmandu valley, Nepal were also carried out to evaluate the usefulness of SEM pollen identification. It was possible to detect climatic change only when SEM was used in addition to light microscopy (LM). The accuracy of the reconstruction of the Himalayan palaeoclimate by means of pollen analysis is improved when SEM is applied to the identification of Himalayan fossil Pinus and Quercus pollen grains.

1. Introduction

Fossil pollen assemblages are generally dominated by anemophilous plants because they produce much larger quantities of pollen grains than entomophilous plants (Erdtman, 1952). In the Himalayan area, the most typical anemophilous tree genera that can form large pure forests are Pinus and Quercus. Those two genera are distributed over a remarkably wide range of elevations, from just above the subtropical zone up to the tree line. The Himalayan fossil pollen assemblages, therefore, tend to be dominated by these two genera (Stainton, 1972; Tabata et al., 1988). This 0034-6667/96/$15.00© 1996ElsevierScienceB.V. All rights reserved SSDI 0034-6667 ( 95 ) 00072-0

means that the occurrence of Pinus and/or Quercus in these fossil pollen assemblages does not suggest well-defined palaeoclimatic conditions. On the other hand, the distributional areas of Pinus and Quercus can be divided into subzones in which particular species of Pinus and Quercus are distributed (e.g. Stainton, 1972; Tabata et al., 1988). The distributional area of each species of one genus scarcely overlaps and is relatively narrow in comparison with that of each genus. Species-level identification of Himalayan Pinus and Quercus may facilitate reconstructions of palaeovegetation and palaeoclimate in the Himalayan area. For this purpose, scanning electron micro-

318

T. Nakagawa et al./Review ol Palaeobotany and Palvnology 91 (1996) 317 329

scope (SEM) must be used since it is usually impossible to discriminate Pinus and Quercus species by only light microscope (LM). In northwest Europe, Benthem et al. (1984) documented the pollen morphology of the Fagaceae using both LM and SEM and showed that ultrastructual detail of the exine surface is useful in distinguishing European Quercus species. Bagnell (1975) established the pollen morphologies of Abies, Picea, and Pinus of the Rocky Mountains using SEM and suggested the possibility of species-level fossil identification by SEM. In the Himalayan area, however, no pollenmorphological studies have been carried out by SEM to date. In this paper, the pollen of modern and fossil Himalayan Pinus and Quercus species have been compared using SEM to ascertain whether it is possible to identify individual species. Also pollen analyses on sediment samples taken in the Kathmandu valley, Nepal (central Himalayas) were carried out to verify the usefulness of SEM in Himalayan palynological studies. 2. Materials and methods

2.1. Modern samples Modern pollen samples of Pinus roxburghii, P. wallichiana, Quercus semecarpifol&, Q. incana, Q. lanuginosa, and Q. glauca were treated according to the modified method of Miyoshi (1981). The processing sequence of the samples is as follows: KOH treatment-wash~:lehydration (acetic acid) acetolysis~tehydration-wash-fix (Carnoy's fluid) ethanol treatment-isoamylacetate treatment-dried and Pt coated. The materials were examined with a JSM-6300 scanning electron microscope of JEOL Ltd., Co. Saccus height, saccus width at base, corpus breadth, and surface sculpture of cappa (proximal side of corpus) were selected as the key characteristics for the description of Himalayan Pinus pollen grains (Fig. 1). Polar axis and equatorial diameter were selected as the dimensions for the description of Himalayan Quercus pollen grains. Surface sculpture and exine ornamentation of Himalayan Quercus pollen grains were also described. At least 15 pollen grains were examined and

Leptoma

.'~.. C Distal side

i~

A

~'~i

Cappa

Proximal side

Fig. 1. Dimensions of Pinus pollen grains measured. A = corpus breadth; B = saccus height; C = saccus width at base.

measured for each collection. Most of the descriptive terms were taken from Erdtman (1952) and F~egri and Iversen (1975). The specimens of original plants are housed in the Herbarium of Kyoto University (KYO) or in the National Herbarium of the Department of Forestry and Plant Research, Kathmandu, HMG of Nepal (KATH). Modern specimens examined are as follows: Pinus roxburghii Sargent-H. Tabata et al. 7776 (KYO); Solu Khumbu District (alt. 1400 m), Nepal. Pinus wallichiana A.B. Jackson H. Tabata et al. 10187 (KYO), Ramechhap District (alt. 1750-1880 m), Nepal; H. Tabata et al. 10164 (KYO), Dolakha District (alt. 1880-2400 m), Nepal. Quercus semecarpijblia Smith-H. Tabata et al. 14971 (KYO), Lake Rara National Park, Nepal; H. Kanai 14971 (KYO) and 673150 (KYO), Singum Gompa (alt. 3000 m), Nepal. Quercus incana Roxburgh-H. Hara et al. 8140 (KYO), in Darjeeling, Sikkim (alt. 2000 m), India; P. Pradhaneral 1037 ( KATH ), Dadelduira, Nepal. Quercus lanuginosa D. Don-H. Kanai 11304 (KYO), Kathmandu (alt. 1500 m), Nepal; H. Kanai et al. 16703 (KATH), Mt. Nagarjhun (alt. 2050 m), Nepal; T.B. Shrestha 15111 (KATH), Sangun Danda (alt. 1400 m), Nepal. Quercus glauca Thunberg-N.P. Manandhar 1-1027 (KATH), Nepal.

2.2. Fossil samples Pleistocene lacustrine sediments were sampled in the Gokarna area, Kathmandu Valley, Central Nepal (27°42'28"N, 85°23'39"E). Fig. 2 shows the

T. Nakagawa et aL/Review of Palaeobotany and Palynology 91 (1996) 317-329

N j

.rT~-/ /// / fk,,,,? Bagmati R. E , - . J l

-;.ZZ_-+_L --. t",. I ~.~ ) [ [Z]:Gokarna geomorphicsurface ft J f -~ -

"T-2 80 °E

82 °E

84 °E

319

~6 °E

o 88 °E

,oo_.

~JO ~

Manohara R.

Fig. 2. Map showing the location of the sampling site in the Kathmandu valley.

location of sampling site. A columnar section and the sampling horizons are shown in Fig. 3. Fossil pollen grains were extracted from the sediments by heavy liquid (70% ZnCI2 solution) and processed in the same sequence as that for modem pollen samples. More than 500 pollen grains and spores (mounted in 50% glycerin) were identified with LM, and more than 50 pollen grains of both Pinus and Quercus were identified at species level with SEM. The pollen diagram of the LM analysis was constructed in terms of percentage of total pollen. The results of the SEM analysis are shown in synthetic graphs.

chemical treatment in the procedures). No variation between specimens was recognised within each species.

3. Results

(2) Pinus wallichiana A.P. Jackson (Plate I, 5, 7)

3.1. SEM pollen morphology of Himalayan Pinus Pollen grains of the two Himalayan Pinus species have a pair of sacci (bisaccate). The breadth of the corpus is 46 ,-~53 i~m. The height of the saccus is 15~21 txm and the width of saccus at the base is 25--~30 ~tm (it should be noted that they are smaller than their original size because of the

(1) Pinus roxburghii Sargent (Plate 1, 1, 3) The juncture of corpus and sacci is sharp. The surface of cappa is remarkably rough and the sculpture of cappa is rugulate. The width of the rugulae is 0.6 ~ 1.5 gm. Leptoma and sacci have a smooth exine although very fine pinholes are scattered on the sacci. The breadth of the corpus is 46,-,49 tam. The height of the saccus is 17 ~21 gm and the width of saccus at the base is 25 ~ 28 gm.

The juncture of corpus and sacci is not very clear. The surface of cappa is not roughened. The sculpture of cappa is smooth or slightly rugulate. Leptoma and sacci have a smooth surface. The exine of the sacci has pinholes similar to Pinus roxburghii. The breadth of the corpus is 49,-,53 lam. The height of the saccus is 16~ 19 ~tm and the width of saccus at the base is 27 ~ 30 I~m.

71 Nakagawa et al./ Review o/' Palaeobotan y and Palynology 91 (1996) 317 329

320

30

...';. = .'... ;.'..

39

15

(m) -:

• .'.-.

~;~...-.1 ~

...'...

.... ...'...

,

•".::'."-'."I . ' : . ' = .'.. [

• .-... • '*'

,

..'.: .'..-'." I -*." .'." ,',' ( .%'.':.':1

..\. .: .....

.'," , ' : -'.'1

'.

, ' : ,'." .'," I

'." . ' . " .

,'." .'," ,'." I ,-....

•. . . . . .

'.'.':'... ":.'."

25 ) G o k 142

35

.'."-'." .'.'~ ,'," , ' ; -'." I

•....:. ..... :....

.'." . ' : ,'." I ..'- :'

10

ill

)Gok 141 ) Gok 139

o,,01

oo,1,

• ...-..

• '." ,'," "." I .' • ,':

y .r J-_l

• ...-=.

.':-':-%'1

?Ii t

) G o k 137 I

'.%'-'.'.'=1

•,..'.. ,.. ,-.. -...'.

) G o k 134

'*%" , ' : -'.'1

~

"..'.. .....

20

.'..]

3(]

, ..-.

( )Gok 168 --,

%..':

(>Gok 153

.'1." ..i.. .'1-" .o1.. .'1." ..i.. .'1." %..'.

•1"| • ~~...J _-~-.~ "i)Gok 132 ......,

2i~.: %.,'.,

"1.'1.'1.(

;[::l..":l:'i ~ ".'" ".'! "Y,

-,. , . , .

.: .."< -: .: ..".,

• ...'..

= ..; .'...'.. .......

-,...,.

I113 lJ Silty Sand

• ,..,..

': ".": .'! ".'",' : .'; .'; .';

• / ¢ •Lignite

.: ..".: .- .: ..'

0 Gok

i:::i~

O G o k 128

130

15

,...'.,

for:a5

~'-~:~':~

Gravel

F i g . 3. L i t h o l o g y o f the sampling site and sampling h o r i z o n s • F i f t e e n samples were taken m a i n l y f r o m fine-grained (clay silt) layers. Total length o f the sequence is 39 m .

3.2. S E M pollen morphology of Himalayan Quercus The shape in equatorial view is elliptical or circular, the amb is circular; polar axis is

18 ~ 25 Iam and equatorial axis is 18 ~ 24 lam long. All grains are 3-colporate, the colpi lens-shaped with a membrane that consists of very small rods, the pores elliptical or circular and situated on the equator. The surface sculpture consists of ran-

T. Nakagawa et al./Review of Palaeobotany and Palynology 91 (1996) 317-329

321

(3) Quercus lanuginosa D. Don (Plate III, 1, 2) Nearly identical to Quercus incana. The polar

domly oriented rods, which, in some species, aggregate into microverrucae. No variation among the collections of the same species was found.

axis is 21 ~ 23 txm in length and the equatorial axis is 20 ~ 24 lam in length.

(1) Quercus semecarpifolia Smith (Plate II, 1, 3)

(4) Quercus glauca Thunberg (Plate III, 3, 5)

Their equatorial view is elliptical, amb being circular or subtriangular. Colpi are 2 ~ 3 ~tm wide. The surface of the exine consists of very small, randomly oriented rods. These rods are found everywhere except on the colpi. Sculpture is scabrate. Very minute microverrucae (0.1 ~ 0.2 txm in diameter) are distributed on the colpus membrane but these microverrucae do not consist of rods like those on the general surface. The polar axis and equatorial axis of the pollen grains are 20 ~ 25 txm and 18 ~ 22 lam in length, respectively.

The outline is spheroidal. Colpi are 1.5,,~2 ~tm wide. The exine surface probably consists of fine rods which aggregate so tightly and are nearly buried in the matrix that each rod is not clearly visible. These rods are poorly aligned and form ridges which are 0.3~0.4 tma wide. The sculpture is microscabrate. The rods and ridges densely cover the whole surface except colpi. The colpi are sparsely covered with spinules. The polar axis is 18 ~ 22 ~m in length and the equatorial axis is also 18 ,-~22 ~tm in length.

(2) Quercus incana Roxburgh (Plate II, 5, 7)

3.3. SEM pollen analysis in the Kathmandu valley

Their equatorial view is spheroidal. Colpi are 2,-~ 3 ~tm wide. The exine surface consists of fine rods, which are similar to those of Quercus semecarpifolia. These rods aggregate into microverrucae, the diameter of which is 0.7~ 1.0 ~tm. The microverrucae are densely distributed all over the surface except on the colpi. Sculpture is microverrucate-scabrate. On the colpus membrane, only traces of these microverrucae can be seen. The polar axis is 20~231am in length and the equatorial axis is also 20 ~ 23 ~tm in length.

The results of pollen analysis are shown in Fig. 4. The fluctuation patterns of total Pinus and Quercus (LM results) are rather chaotic but it is possible to recognise 8 local pollen zones from the fluctuation pattern of each species or type (SEM results). However, it is a still tentative zonation for the resolution of the analysis is not high enough (note that a reconstruction of palaeoclimate in the Kathmandu valley is not intended in the present paper).

PLATE 1 (see p. 322) Comparison of modem and fossil pollen grains of Himalayan Pinus. 1-4. P. roxburghii. 5 8. P. wallichiana. 1, 3, 5, 7: Modem sample. 2, 4, 6, 8: Fossil. Note that the surface sculptures are maintained very well even in fossil samples whereas the outlines are severely damaged. PLATE 1I (see p. 323) Comparison of modem and fossil pollen grains of Himalayan Quercus. 1-4. Q. sernecarpifolia. 5, 7. Q. incana. 6, 8. Q. incana type. 1, 3, 5, 7: Modem sample. 2, 4, 6, 8: Fossil. Note that the surface sculptures are maintained very well even in fossil samples whereas the outlines are severely damaged.

72 Nakagawu et al. ,Review of Palaeobotany and Palynology 91 (1996) 317 329

322

PLATE l

Modern

Fossil

lOpm

lOpm

lpm

1pro

lOpm

m

(for description see p. 321 )

lpm

10

pm

lpm

T. Nakagawa et aL/Review of Palaeobotany and Palynology 91 (1996) 317-329

323

PLATE II

Modern

Fossil

10 p m

10 #m

(3

-

-

lpm

-

-

I p m

10 p m

10 p m

(3

--. (for descri ~tion see p. 321 )

1pro

-

-

1/Jm

T. Nakagawa et al./Review qf Palaeobotanv and Pulynology 91 (1996) 317-329

324 P L A T E 1II

!!

Modern

Fossil

(b 10 pm

indistinguishable from fossil pollen grains of Q. incana

(3

1 pm

10 pm

10 p m

(3

lpm

~

lpm

T. Nakagawa et al./Review of Palaeobotany and Palynology 91 (1996) 317-329

LM

SEM

325

tO N t-

.m

I:1.

"o

0 "=

~

"0 ~

Q2

,

I u

171 ~ , ~ 168

m

O

O

J

i

.................. ~:,:;:::;:+~:.~:~:;:....::::~::~

GoR -Vlll Gok-Vll

:::::::::::::::::::::::::

165 163

O

['

Gok-Vl

161

E::::::I

157

Gok-V 153 I

142 141 ~

i

139

I

137

::::::::::::::::::::::::::

, r~,.:.:~.~

Gok-IV

L

i

1341 .....

130

:~.:.:.:.: m

~:.:.:.:....~

G0k-III

~;:::::::::::::~

Gok-II

[

128

r i

i

i

10

i

,

20

,

i

30

,

,

40

i

i

i

10

i

r

20

i

i

30

r

'

40

i

i

50

i

i

60

i

~

i

70

Gok-I r 50

i i 100

50

I

i 100

Fig. 4. Pollen diagram of selected taxa showing the results of LM (left) and SEM (right) pollen analysis. Pollen zones and summarised climatic change are also shown. Three cold-warm oscillations can be induced from the results of SEM analysis.

The characteristic features of each pollen zone is as follows:

Gok-III (Gok 134-137) Q. glauca shows remarkably high value (more than 70%) in this zone.

Gok-I (Gok 128-130) The values of P. wallichiana and Q. semecarpifolia are high (more than 50%) in this zone. Gok-IV (Gok 139-142) Gok-H (Gok 132) Q. incana type pollen becomes dominant and the value of P. roxburghii decreases in this zone.

This zone is characterised by quite high values of P. wallichiana and Q. semecarpifolia. The value of Q. semecarpifolia reaches 92% at maximum.

PLATE II1 Comparison of m o d e m and fossil pollen grains of Himalayan 1-2. Q. lanuginosa. 3-6: Q. glauca. 1, 2, 3, 5: M o d e m sample. 4, 6: Fossil.

Quercus.

T. Nakaga~a et aL/Review oj Palaeobotany and Palynology 91 (1996) 317 329

326

Gok- V (Gok 153-157) The values of P. roxburghii and Q. incana type are quite high in this zone making a sharp contrast with lower zone Gok-IV.

Gok-V1 (Gok 161 165) Q. semecarpifolia increases upward in this zone. Q. glauca occurs in a relatively high value. Gok- VII (Gok 168) The value of Q. semecarpijolia is relatively high in this zone although it is not as high as in Gok-IV zone. The reduced value of Q. glauca should also be noted.

Gok- VIII (Gok 171) Pinus pollen grains in this zone consists completely of P. roxburghii. The value of Q. incana type is also high in this zone.

4. Discussion

4.1. Key characteristics and identification oj" Himalayan Pinus and Quercus pollen grains The purpose of this study is to enable the identification of fossil pollen grains of Himalayan Pinus and Quercus species. Although the dimensions of pollen parts are important in descriptions of modern pollen, fossil pollen grains are generally observed in conditions or orientations where many parameters are not measurable. Moreover, shape or size of fossil pollen grains can change in sediments or through the chemical treatment in the processing sequence. The surface structure, on the Table 1 Characteristics of Himalayan Pinus pollen Saccus Height

P. roxburghii P. wallichiana

17421 16 ~ 19

Corpus Width at base

Breadth

25~28 27 ~ 3fl

46~49 49 ~ 53

Cappa sculpture Rugulate Smooth slightly rugulate

other hand, is generally well retained and can be observed in detail even on a small fragment of the fossil exine. Thus, it is more reasonable to use the surface structure for the identification of Himalayan fossil Pinus and Quercus pollen grains. The results of discriminant analysis are summarised as in Tables 1 and 2. The pollen grains of Pinus roxburghii have clearly rugulate sculpture on the cappa while those of P. wallichiana are smooth or slightly rugulate. It is therefore possible to identify the pollen grains of P. roxburghii and P. wallichiana at species level by SEM. Plate I shows the comparison of modern (left) and fossil (right) pollen grains of the two Himalayan Pinus species. These two species can be distinguished from each other. No other modern Pinus species have been reported from the Nepal Himalayas. This means that every Pinus species can be identified by SEM pollen analysis provided no other Pinus species have ever occurred in the Nepal Himalayas. The surface structures of Quercus incana and Q. lanuginosa are more or less similar, having the randomly oriented small rods aggregated into microverrucae. Quercus semecarpifolia has scabrate sculpture on the surface and the minute rods are distinct. The surface sculpture of Q. glauca is microscabrate and only traces or tips of minute rods are visible. Fossil pollen grains of Himalayan Quercus, therefore, can be divided into Q. semecarpifolia type, Q. incana type (which potentially contains at least Q. incana, and Q. lanuginosa), and Q. glauca type when the SEM is used. Plates lI and IlI compare modern (left) and fossil (right) pollen grains of Himalayan Quercus species. It is possible to discriminate Q. semecarpiJolia, Q. glauca, and Q. mcana type. No other Quercus species in the Himalayan area constitutes forests on such a large scale as these do. The importance of minor Quercus species in Himalayan fossil pollen assemblages is considered to be much less than that of the four dominant species. It may be concluded that some Himalayan fossil Quercus pollen grains can be identified with the help of SEM.

4.2. Species-climate correlation The distribution of Pinus and Quercus species is related to specific climate zones (e.g. Stainton,

T. Nakagawa et al./Review of Palaeobotany and Palynology 91 (1996) 317-329

327

Table 2 Characteristics of Himalayan Quercus pollen Size (#m)

Q. semecarpifolia Q. incana Q. lanuginosa Q. glauca

Polar

Equatorial

20~25 20 ~ 23 21 ~ 23 18~22

18~22 20 ~ 23 20 ~ 24 18~22

Main sculpture

Condition of rods

Scabrate Microverrucate-scabrate Microverrucat~scabrate Microscabrate

Distinct Aggregated into microverrucae Aggregated into microverrucae Tightly aggregate and not clear

1972; Tabata et al., 1988) as is shown in Fig. 5 (constructed after Klotz, 1966; Numata, 1966; Meusel and Schubert, 1971; Stainton, 1972; Malla et al., 1976; Ohsawa, 1987; Tabata et al., 1988; Shresta, 1989; Tabata, unpubl, data). Pinus roxburghii is restricted to warm areas whereas P. wallichiana is restricted to cold areas; therefore, they can be indicators of warm or cold climates in the past, respectively. The boundary between distributional areas of P. roxburghii and P. wallichiana is around 2000 m elevation today. P. wallichiana occurs up to 3500 m in elevation. The temperature lapse rate in the Himalayan area is 0.6°C/100 m (Ohsawa et al., 1983) and the elevation of the Gokarna area is about 1350 m. This indicates that the local pollen zones in which P. wallichiana is dominant represent a 4-13°C lower mean annual temperature than the present in the Kathmandu valley. As for Quercus species, Q. semecarpifolia is typical for cold (both wet and dry) areas, whereas Q. incana type is typical for warm areas (it is not distributed in wet areas but not necessarily specific to dry areas, distributed from central to western Himalayas). Quercus glauca is typical for warm and wet areas. This means that fossil pollen grains of Q. semecarpifolia and Q. incana type can be indicators of past cold and warm climates, respectively. Q. glauca can be an indicator of a wet and warm climate as well. The boundary between Q. semecarpifolia and Q. incana type lies around 2500 m in elevation today. Q. semecarpifolia occurs up to the tree line, which is approximately at a height of 3600 m. Provided the same temperature lapse rate and the elevation of Kathmandu valley, it is suggested that the dominance of Q. semecarpifolia in local pollen assemblage shows a 7-13°C lower

mean annual temperature than the present in the Kathmandu valley.

4.3. Importance of SEM pollen identification in Himalayan palynological studies Each tentative pollen zone in the Gokarna area is interpreted as follows: Pollen zones with a high value of Q. semecarpifolia or P. wallichiana, such as Gok-I, Gok-IV, and Gok-VII, indicate a cold climate in the periods represented by these zones. The mean annual temperature was at least 4-7°C lower than the present in these periods. On the other hand, pollen zones with high values of Q. incana type and P. roxburghii, such as Gok-II, Gok-V, and Gok-VIII, indicate warm climates, comparable to the present, in the periods represented by these zones. The remarkable richness of Q. glauca in the Gok-III zone shows the warm and wet climatic conditions in the period represented by this zone. The occurrence of Q. glauca and the upward increase of Q. semecarpifolia in the Gok-VI zone show the wet condition and the climatic deterioration through this period. The above interpretations suggest three oscillations between cold and warm climates throughout the sequence. It is possible to reconstruct an outline of palaeoclimatic change only when SEM is used for pollen identification. Species-level identification of Himalayan Pinus and Quercus pollen with SEM will permit a much more reliable reconstruction of the Himalayan palaeoclimate than LM.

7~ Nakagawa et a/.'Review o) Palaeobotany and Pal.vnology 91 (1996) 317-329

328

...~o,m, I I

Quercus semecarpifolia

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::~ ~"

~ J ~ - " ~ Western Midland f ~/(~/t~ Central Midland

~i~:::i~:i:i:i:i:i:~i:i::J:i:i:~:i:~i:ii~:!:. i~~ia:~~!:o:i:wi:~:~i:~:i:i i•i:i:i:i:iiiii••ii•i•i•i•i:••:;!;!i•i•:ii:i:i:i:i:i:i:•:i:•:ii]

30o0 ~"

"~;"' ~ Kumaon "

Nepal

i:i:/:i!;illi~ii~!i~:~: :;:~i ii~:i!l:;~ii~i~

~'~" ..............

o ~c~ . . . . . . . . . . . . . . . . . .

Sikkim ~

j

.:iii:::~

Kathmandu . . . . . . . . . . . . . .

b

0 .~

!ii!!'~"

JundaK=u~hmir Kumeon Humkl

I Midlar¢l Cerllr=lJ E=

WNt

Sikkim

Bhutan

i

"~ West / Xeric ~.:::ii.::.:.~.:~:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:~:~.:.:~:.:.:.:~:.:~:.:.:.:.:.:.:~:.:.:~:.:.:.:.~!iiii:~..~ East / Mesic

,..,o.~m~

Pinus roxburghii

,,,.,,=,.~m~

Ouercus incana / lanuginosa

5000 =========================================================================================================== -r"

...............

Only O . / o n u ~ n o ~

I

3000

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

,ooo . . . . . . . . . . . . . . . . . . . . . . .

Jumla-

West

[Central I Midl~KI

India K--.rKu--

.__.

N=r~

o Eut

t[

j°~,.w,~ I cMidland .~l Humkl

Kalmhm~r K urr~on

Bhutan

india

I

3

West / Xeric ~:~:~:~i~i:~:.:~:~:~:~:~:.:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~.~:.~:+:~:.:~:+:~:.:~:~East :~:`:~:~:~i;:ti~.Mesic

,..=on~.~

•

Sikkim

,r~=

Kathm~~

I

.:i.

............

~.=

"~

I

' ":::::? =~

Sikkim

Bhutar

I ,n~= I

:~

W e s t / Xeric ~:~:~i!!!:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:.:.:~:+:.:.:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~::!?~:~:~ - East / Mesic

Pinus wa//ichiana

..v.=.~m~

Quercus glauca

5000 ::ii::~::~i::~i::~:i!i::~i::.!:1~i::~::~i :::~:i~::~::~:i:~:::~:::~::~::~::~::ii::~i::~::~i::~::::~i ~::~ii~:::~i :~i~::~::i :i::~::i i~i:i~i::~iii :~ ::ii~:::~::~:::~:~ -140oo

E 3oo0

limited to very mesic habitat

.:ii::i~:

2ooo

-t ...................

................

O[K~mir KumaontJUHr~urnllaWeet I~1 I

,.,,

I

~*=

East I Bikkim ]Sh~ I ,~. I

/:

/

West / Xeric .-:~:~!!ii:.! .................................................................................. :::ii;i:i:-..East / Mesic

;

1ooo . . . . . . . . . . . . . . . . o

K.=.m,. Ku.=° J ° ~ ; =

nd~

:~ii:::

Ka~°mndu ....

w.= I .c~.=l E.= ~=.

Nep~

S~,ki~ B.=..

I India

"

West / Xe d e -~:~::.:~i~!:~:.:.:.:.:`:~:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.::::i.;i::: East / Meste

Fig. 5. The l o n g i t u d i n a l and a l t i t u d i n a l d i s t r i b u t i o n s o f H i m a l a y a n Pinus a n d Quercus species. The a l t i t u d i n a l axis is e q u i v a l e n t to the axis o f m e a n a n n u a l t e m p e r a t u r e a n d the l o n g i t u d i n a l axis is e q u i v a l e n t to t h a t o f humidity. The d i s t r i b u t i o n s o f P. wallichiana a n d Q. semecarpifolia are limited to high (cold) areas and those of P. roxburghii, Q. incana, a n d Q lanuginosa are limited to low (warm) areas. Q. glauca is specific to eastern (wet) areas.

T. Nakagawa et al./Review of Palaeobotany and Palynology 91 (1996) 317-329

Acknowledgements The authors sincerely thank Drs. D.P. Agrawal, B.N. Upreti, and Mr. H. Kitagawa for their useful suggestions; all the staff in the Center for Ecological Research, Kyoto University for their intensive discussion and encouragement; Drs. T. Setoguchi, K. Chinzei, T. Ohno, and H. Maeda for offering us various information; and Dr. J.R. Flenley for his critical reading and valuable advice. This work has been supported by the project "Environment and Civilization" of which Dr. S. Ito is the representative.

References Bagnell Jr., C.R., 1975. Species distinction among pollen grains of Abies, Picea, and Pinus in the Rocky Mountain Area (a scanning electron microscope study). Rev. Palaeobot. Palynol., 19: 203-220. Benthem, F.V., Clarke, G.C.S. and Punt, W., 1984. The Northwest European Pollen Flora 33. Fagaceae. Rev. Palaeobot. Palynol., 42:87-110. Erdtman, G., 1952. Pollen Morphology and Plant Taxonomy. Angiosperms. Almqvist and Wiksell, Stockholm, 539 pp. Faegri, K. and Iversen, J., 1975. Textbook of Pollen Analysis. Munksgaard, Copenhagen, 3rd ed., 295 pp. Klotz, G., 1966. Beitrage zur Flora und Vegetation Indiens. Wiss. Z. Univ. Halle., 15: 97-148. Malla, S.B., Shresta, A.B., Rajbhandari, S.B., Shresta, T.B.,

329

Adhikari, P.M. and Adhikari, S.R., 1976. Flora of Langtang and Cross Section Vegetation Survey (Central Zone). Dep. Medicinal Plants, Kathmandu, 269 pp. Meusel, H. and Schubert, R., 1975. Beitrage zur Pflanzengeographie des Westhimalajas, I, II, III, pp. 137-194; 373432; 573-606. Miyoshi, N., 1981. Pollen morphology of Japanese Quercus (Fagaceae) by means of scanning electron microscope. Jpn. J. Palynol., 27: 45-54. Nakagawa, T., Yasuda, Y. and Tabata, H., in prep. Reconstruction of Pleistocene climatic change in Kathmandu valley, central Himalayas. Numata, M., 1966. Vegetation and conservation in eastern Nepal. J. Coll. Arts Sci. Chiba Univ., 4: 559-569. Ohsawa, M., 1987. Vegetation zones in Bhutan Himalaya. In: M. Ohsawa (Editor), Life Zone Ecology of the Bhutan Himalaya. Chiba Univ., Chiba, pp. 1-72. Ohsawa, M., Takiguchi, S., Shakya, P.R. and Numata, M., 1983. Forest types and distribution in the Tamur river basin, east Nepal. In: M. Numata (Editor), Ecological Studies in the Tamur River, East Nepal and Mountaineering of Mt. Makalu I1, 1977. Himalayan Comm. Chiba Univ., Chiba, pp. 85-111. Shresta, B.P., 1989. Forest Plants of Nepal. Educational Enterprise, Kathmandu, 216 pp. Stainton, J.D.A., 1972. Forest of Nepal. Hafner, New York, NY, 181 pp. Tabata, H., Tsuchiya, K., Shimizu, Y., Fujita, N., Matsui, K., Koike, F. and Yumoto, T., 1988. Vegetation and climatic changes in Nepal Himalayas. I. Vegetation and climate in Nepal Himalayas as the basis of palaeoecological studies. Prec. Indian Natl. Acad., 54: 530-537. Yasuda, Y. and Tabata, H., 1988. Vegetation and climatic change in Nepal Himalayas If. A preliminary study of the Holecene vegetational history in the Lake Rara national park area. Prec. Indian Natl. Acad., 54: 538-549.