Species Composition, Physiognomy and Plant Diversity of the Tropical Montane Evergreen Broad-leaved...

Species composition, physiognomy and plant diversity

of the tropical montane evergreen broad-leaved forest

in southern Yunnan

H. ZHU*, J.P. SHI and C.J. ZHAOXishuangbanna Tropical Botanical Garden, The Chinese Academy of Sciences, Xue Fu Road 88,

Kunming 650223, Yunnan, P. R. China; *Author for correspondence (e-mail: [email protected]; fax:

86-871-5160916)

Recieved 2 October 2003; accepted in revised form 13 April 2004

Key words: Biodiversity, Physiognomy, Species composition, Southern Yunnan of China, Tropical

montane evergreen broad-leaved forest

Abstract. Species composition, physiognomy and plant diversity of the less known tropical mon-

tane forests in southern Yunnan were studied based on the data from 15 sampling plots in three

sites. These forests are mainly dominated by the families Theaceae, Fagaceae, Lauraceae and

Euphorbiaceae in floristic composition, and dominated by evergreen phanerophytes with meso-

phyllous leaves. These forests are similar to lower montane rain forests in equatorial southeastern

Asia in floristic composition and altitudinal distributions, but differ in physiognomy by having few

epiphytes, but more lianas and more plants with compound leaves. These differences could be due

to strongly seasonal climate and so-called mass elevation effect in southern Yunnan. They also

differ from the tropical seasonal rain forests at lower altitudes in southern Yunnan by having

conspicuously lower species richness, few epiphytes, fewer mega-mesophanerophytes, more abun-

dant micro-nanophanerophytes and hemicryptophytes and more plants with microphyllous leaves.

It is suggested that these forests could be termed tropical montane evergreen broad-leaved forests,

and be a vegetation type from the northern margin of mainland southeastern Asia controlled by a

strongly seasonal climate.

Introduction

Southern Yunnan province of southwestern China is exceptionally interesting tobotanists because of its diversified biota and particularly geological–biogeo-graphical history. The region is the area with the greatest species richness and thelargest tropical–subtropical forest cover in southern China. The region is at atransitional zone from tropical Southeast Asia to subtropical East Asia geo-graphically, and is also geologically thought to be a conjunction area betweenShan-Tai fragment of Gondwanaland and the southeastern margin of Asiancontinent (Fortey et al. 1998; Metcalfe 1998). Southern Yunnan is therefore akey area in biogeography and a hot spot for biodiversity (Myers 1998).

The vegetation of southern Yunnan was briefly mentioned for the first timeby Wang (1939), but little known until late 1950s because of poor access. AChina–Russia expedition penetrated deep into the areas of southwesternChina, including southern Yunnan, in the late 1950s, and some descriptiveworks on the tropical forest vegetation of this part of China were published

Biodiversity and Conservation (2005) 14:2855–2870 � Springer 2005

DOI 10.1007/s10531-004-8220-x

(Qu 1960, Wang 1961). Further studies on the tropical forests in southernYunnan have been done although few have been published in English (Wu1987; Zhu 1992, 1993; Cao 1996; Cao and Zhang 1997; Jin 1997; Zhu 1997;Zhu et al. 1998a, b, 2002). Previous work on the forest in southern Yunnan wasmainly done in lowland tropical rain forests and in lower montane forest below900 m, while tropical montane forests, which are distributed above 900 maltitude and cover the largest area in this region, are still little known except forsome descriptive works (Jin 1979; Wu 1987; Shimizu 1991).

Tropical montane evergreen broad-leaved forests, the main montane foresttype in southern Yunnan, are dominated mainly by the families Theaceae,Fagaceae, Lauraceae and Euphorbiaceae, and are similar to lower montanerain forests in equatorial southeastern Asia in floristic composition and alti-tudinal distributions, but differ in physiognomy due to the strongly seasonalclimate and the so-called ‘Massenerhebung’ or ‘mass elevation effect’ in theregion (Whitmore 1990). The montane forests are important both for theirspecies richness, and also biogeographic connection that they form betweenIndo-Malesian tropical rain forest and eastern Asian subtropical forest.

General geography

Topography

Southern Yunnan lies in the southern-most part of Mainland China (Figure 1).It borders Myanmar and Laos, and has a mountainous topography with themountain ridges running north south and becoming lower in elevation

Figure 1. The map shows the sites and locations of sampling plots in southern Yunnan of

southwestern China.

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southward. Altitude ranges from 480 m at the bottom of the lowest valley inthe south (Mekong River) to 2429.5 m at the top of the highest mountain in thenorth. The Mekong River flows through the region from northwest to south-east (Xu et al. 1987; Cao 2003).

Climate

Southern Yunnan has a typical monsoon climate. From the Simao county cli-matic station at an altitude of 1302 m, the mean annual temperature is 17.7 �C,the coldest monthly mean temperature 11.4 �C, the annual temperature accu-mulation (the sumof daily temperaturemeans of>10 �C) 6253 �Cand themeanannual precipitation 1547.6 mm. More than 80% of the precipitation fallsduring the rainy season between May and the end of October (Cao 2003).

Methods

Three sites at similar altitudes and covered by well-conserved tropical montaneevergreen broad-leaved forests were chosen for plotting (see Figure 1). One siteis located at Nangong Mt. in the south of the region near the Yunnan–Laosborder. The second site is in Mengsong in the west of the region at the Yunnan–Myanmar Border. The third site is in Caiyanghe nature reserve in the north ofthe region. Five almost contiguous plots of 25 � 20 m in size were laid out ateach site. All trees in these plots were identified and their d.b.h. (minimum5 cm), height and crown cover measured. In each plot, five 5 � 5 m sub-plotswere set for floristic survey of the understory. In these sub-plots, saplings,shrubs and herbaceous plants were counted. Lianas in these plots were identi-fied and their abundance estimated. Importance value indices (IVI) of Curtisand McIntosh (1951) were calculated. Rank/abundance diagrams (Magurran1988) of species in each site were plotted. Shannon–Wiener index (Shannon–Wiener 1949) for species diversity were calculated from plot data. Physiognomy(life forms and leaf size) was analyzed using Raunkiaer’s criteria (Raunkiaer1934) revised by Mueller-Dombois and Ellenberg (1974). Specimens were col-lected and identified. Species authorities follow Flora Reipublicae PopularisSinicae (Flora of China). Specimens are kept in the herbarium HITBC.

Results

Species composition

These tropical montane evergreen broad-leaved forests, which occur on mon-tane slopes between 900–1800 m altitudes, usually have two conspicuous treelayers, of which the upper tree layer is 15–30 m tall with dense crowns, and thelower tree layer is 3–18 m tall with a cover of ca. 50%. These forests are

2857

dominated by Fagaceae, Theaceae and Lauraceae families, but diversified inspecies composition in different sites. The understory is mainly composed ofsaplings and seedlings of tree layer species. Shrub and herbaceous species areusually less abundant.

The three sites are diverse in species composition and somewhat different inthe most dominant or sub-dominant species although they are at similar alti-tudes and have a similar physiognomy. We recognized three forest types inthese three sites and name them by their dominant and subdominant species asfollowing: Schima wallichii–Castanopsis hystrix forest, Schima wallichii–Lithocarpus fohaiensis forest and Castanopsis echinocarpa forest.

Schima wallichii–Castanopsis hystrix forest

The Schima wallichii–Castanopsis hystrix forest was plotted in Mengsong, inthe west of the region. The upper tree layer is dominated by Schima wallichii(Theaceae) and Castanopsis hystrix (Fagaceae) (Table 1). The lower tree layeris composed of species from diverse families such as Wendlandia tinctoria(Rubiaceae), Ardisia neriifolia (Myrsinaceae), Ormosia fordiana (Papilionaceae)and Symplocos yunnanensis (Symplocaceae). The shrub layer is 1–3 m tall anddominated by juvenile tree species. The shrub species, such as Wikstroemiaindica, Evodia lepta, Alchornea davidii, Eriosolena composita and Psychotriasymplocifolia were recorded. The herbaceous layer is quite developed and has acover of 50–60%. The common species are Carex baccans, Microstegium sp.,Strobilanthus sp., Smilax hypoglauca, Ophiopogon revolutus and Lophatherumgracile. The common lianas are Craspedolobium schochii, Mussaenda hossei,Embelia ribes and Smilax lanceolata.

Schima wallichii–Lithocarpus fohaiensis forest

This forest was plotted in Caiyanghe, in the north of the region. The upper treelayer is co-dominated by Schima wallichii and Lithocarpus fohaiensis (Table 2).The lower tree layer is dominated by Vaccinium exaristatum. The understory isalso composed mainly of juvenile tree species. The common shrub species areEvodia lepta, Vernonia volkameriaefolia, Ardisia virens. The common herba-ceous species are Carex baccans, Arthraxon lanceolatus, Sarcandra hainanensis,Alpinia blepharocalyx and Smilax hypoglauca. The common liana plants areRourea minor, Craspedolobium schochii and Jasminum lanceolarium.

Castanopsis echinocarpa forest

The Castanopsis echinocarpa forest was plotted in Nangong Mt., in thesoutheast of the region. The upper tree layer is strongly dominated by

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Castanopsis echinocarpa (Table 3). The lower tree layer is dominated by Eu-phorbiaceae and Myrtaceae species such as Aporusa yunnanensis, Glochidionlanceolarium, Syzygium cumini, Syzygium leptanthum. The understory is com-posed mainly of juvenile tree species. A few shrub species were recorded.Common shrubs are Vernonia parishii, Croton kongensis, Glochidion

Table 1. Importance values of tree species in Schima wallichii–Castanopsis hystrix forest.

Species name RA RD RF IVI

Schima wallichii 14.93 36.34 7.14 58.41

Castanopsis hystrix 15.38 23.90 5.71 44.99

Machilus tenuipilis 9.05 3.71 5.71 18.47

Castanopsis mekongensis 4.52 6.62 5.71 16.86

Anneslea fragrans 4.98 5.95 5.71 16.64

Betula alnoides 3.17 5.88 2.86 11.91

Lithocarpus truncatus 4.07 3.50 4.29 11.85

Wendlandia tinctoria 4.98 0.83 5.71 11.52

Ardisia neriifolia 4.07 4.25 2.86 11.18

Lindera metcalfiana var. dictyophylla 7.69 0.40 2.86 10.95

Gordonia chrysandra 4.07 1.55 4.29 9.91

Xanthophyllum siamense 1.81 1.80 4.29 7.89

Metadina trichotoma 2.26 0.58 4.29 7.13

Daphniphyllum majorum 2.71 0.87 1.43 5.02

Illicium micranthum 2.71 0.79 1.43 4.93

Michelia floribunda 1.81 0.11 2.86 4.78

Helicia nilagirica 0.91 0.18 2.86 3.94

Xanthophyllum yunnanense 0.91 0.12 2.86 3.88

Ormosia fordiana 0.91 0.06 2.86 3.82

Lithocarpus fenestratus 0.91 0.66 1.43 2.99

Pithecellobium clypearia 0.91 0.51 1.43 2.84

Elaeocarpus austroyunnanensis 0.45 0.68 1.43 2.56

Symplocos yunnanensis 0.91 0.05 1.43 2.38

Linociera ramiflora 0.45 0.17 1.43 2.05

Cyclobalanopsis myrsinaefolia 0.45 0.14 1.43 2.02

Syzygium brachythyrsum 0.45 0.07 1.43 1.95

Engelhardtia serrata 0.45 0.05 1.43 1.93

Heliciopsis terminalis 0.45 0.05 1.43 1.93

Castanopsis densispinosa 0.45 0.05 1.43 1.93

Scleropyrum wallichianum var. mekongense 0.45 0.04 1.43 1.92

Iteadaphne caudata 0.45 0.03 1.43 1.91

Macaranga denticulata. 0.45 0.03 1.43 1.91

Macaranga kurzii 0.45 0.02 1.43 1.90

Diospyros kaki var. sylvestris 0.45 0.02 1.43 1.90

Acronychia pedunculata 0.45 0.02 1.43 1.90

Canthium parvifolium 0.45 0.02 1.43 1.90

Total 36 species 100 100 100 300

RA: Relative abundance; RD: relative dominance; RF: relative frequency; IVI: importance value

index.

Location: Mengsong, Xishuangbanna; altitude: 1320–1380 m; plot number and size: 5

(25� 20) = 2500 m2; slope degree: 20–30; height of canopy: 30 (m); coverage. >95%; no. of sp.

(>5 cm dbh): 36; no. of stems: 221.

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Table 2. Importance values of tree species of Schima wallichii–Lithocarpus fohaiensis forest.



Lithocarpus fohaiensis 13.42 9.26 5.43 28.12

Vaccinium exaristatum 14.21 5.41 5.43 25.05


Machilus tenuipilis 8.16 2.74 5.43 16.33

Castanopsis hystrix 3.42 11.38 1.09 15.89

Castanopsis echinocarpa 5.53 4.85 3.26 13.64

Castanopsis ceratacantha 5.00 3.81 4.35 13.16

Castanopsis calathiformis 4.74 4.92 2.17 11.83

Anneslea fragrans 2.89 3.13 5.43 11.46

Ternstroemia gymnanthera 1.84 5.60 3.26 10.70

Betula alnoides 1.32 6.46 1.09 8.86

Helicia nilagirica 4.21 2.40 2.17 8.79


Litsea sp. 2.89 1.45 3.26 7.61

Symplocos yunnanensis 2.37 0.78 3.26 6.41

Engelhardtia roxburghiana 1.32 2.78 2.17 6.27

Tricalysia fruticosa 2.11 0.41 3.26 5.78


Michelia floribunda 1.05 0.11 2.17 3.33

Pygeum topengii 0.53 0.38 2.17 3.08

Decaspermum fruticosum 0.53 0.06 2.17 2.76

Millettia cubittii 0.26 1.30 1.09 2.65

Choerospondias axillaris 0.26 1.29 1.09 2.64

Canthium parvifolium 0.79 0.10 1.09 1.97


Lindera communis 0.53 0.10 1.09 1.71

Eurya groffii 0.53 0.08 1.09 1.69

Lithocarpus fordianus 0.26 0.26 1.09 1.61

Myrica esculenta 0.26 0.20 1.09 1.55

Engelhardtia serrata 0.26 0.16 1.09 1.51

Phoebe puwenensis 0.26 0.16 1.09 1.51

Helicia shweliensis 0.26 0.16 1.09 1.51

Radermachera microcalyx 0.26 0.11 1.09 1.46

Macaranga indica 0.26 0.09 1.09 1.44

Olea rosea 0.26 0.08 1.09 1.43

Symplocos cochinchinensis 0.26 0.08 1.09 1.43

Cinnamomum bejolghota 0.26 0.08 1.09 1.43

Helicia pyrrhobotrya 0.26 0.07 1.09 1.42

Eurya cerasifolia 0.26 0.05 1.09 1.40

Acer jingdongense 0.26 0.04 1.09 1.39

Oxyspora paniculata 0.26 0.04 1.09 1.39

Macaranga kurzii 0.26 0.03 1.09 1.38

Millettia sp. 0.26 0.02 1.09 1.37

Machilus salicina 0.26 0.02 1.09 1.37

Pithecellobium clypearia 0.26 0.02 1.09 1.37

Total 46 species 100 100 100 300

RA: Relative abundance; RD: relative dominance; RF: relative frequency; IVI: importance value index.

Location: Caiyanghe, Simao; altitude: 1450–1500 m; plot number and size: 5 (25� 20) = 2500 m2; slope

degree: 15–30; height of canopy: 25 m; coverage: >95%; no. of species (>5 cm dbh): 26; no. of stems:

380.

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eriocarpum and Millettia pachycarpa. The herbaceous layer is undevelopedwith a cover of 10–30%. The common species are Smilax hypoglauca, Carexbaccans and Polygonatum cirrhifolium. The liana plants are dominated byCraspedolobium schochii, and epiphytes are few.

Physiognomy

In 2500 m2 sampling area, 150 vascular plant species, including 87 tree andsapling species, 15 shrub species, 26 herbaceous species and 22 liana species,were recorded from Schima wallichii–Castanopsis hystrix forest in Mengsong;163 species, including 81 tree and sapling species, 15 shrub species, 39herbaceous species and 28 liana species, were recorded from Schima

Table 3. Importance values of tree species of Castanopsis echinocarpa forest.


Castanopsis echinocarpa 57.38 73.57 8.77 139.72


Castanopsis mekongensis 6.96 4.58 8.77 20.31

Syzygium leptanthum 5.27 2.21 8.77 16.26


Aporusa yunnanensis 4.43 0.88 7.02 12.33


Glochidion lanceolarium 0.84 0.21 7.02 8.07

Sapium baccatum 1.90 1.93 3.51 7.34

Metadina trichotoma 0.84 0.14 3.51 4.49

Cylindrokelupha yunnanensis 0.42 0.09 3.51 4.02

Vaccinium exaristatum 1.05 0.26 1.75 3.07

Winchia calophylla 0.42 0.72 1.75 2.89

Millettia pulchra var. yunnanensis 0.63 0.38 1.75 2.76

Cratoxylon cochinchinense 0.84 0.11 1.75 2.71

Machilus rufipes 0.42 0.11 1.75 2.29

Syzygium cumini 0.21 0.26 1.75 2.23

Choerospondias axillaries 0.21 0.26 1.75 2.22


Engelhardtia colebrookeana 0.21 0.13 1.75 2.09

Canarium album 0.21 0.12 1.75 2.08

Horsfieldia glabra 0.21 0.07 1.75 2.03


Millettia leptobotrya 0.21 0.04 1.75 2.01

Phyllanthus emblica 0.21 0.04 1.75 2.01

Cylindrokelupha delatensis 0.21 0.04 1.75 2.00

Total 26 species 100 100 100 300

RA: relative abundance; RD: relative dominance; RF: relative frequency; IVI: importance value

index.

Location: Nangong Mt., Xishuangbanna; altitude: 1170–1200 m; plot number and size: 5

(25 � 20) = 2500 m2; slope degree: 5; height of canopy: 25 (m); coverage: >95%; no. of sp.

(>5 cm dbh): 26; no. of stems: 474.

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wallichii–Lithocarpus fohaiensis forest in Caiyanghe; and a total of 91 species,including 53 tree and sapling species, 14 shrub species, 11 herbaceous speciesand 13 liana species, were recorded from Castanopsis echinocarpa forest inNangong Mt.

The tropical montane evergreen broad-leaved forests in southern Yunnanare dominated by phanerophytes, which make up 80–90% of the total sum ofspecies (Table 4). In leaf size spectra, the plants with mesophyllous leavescontribute to 65–70% of the total species (Table 5). The plants with simpleleaves contribute 72–85% and the plants with an entire leaf margin account formore than 90% of the total species. Deciduous species, which are mainly mega-and meso-phanerophytes, make up less than 10% of the total species (Table 6).

Species diversity

The Shannon–Wiener’s diversity index was higher in Schima wallichii–Litho-carpus fohaiensis forest than in Schima wallichii–Castanopsis hystrix forest, butlowest in Castanopsis echinocarpa forest (Table 8). Schima wallichii–Castan-opsis hystrix forest seems in most mature phase with more trees with large dbh.It is possible that the highest species diversity does not occur in the mostmature phase of forest.

Rank/abundance diagrams of species based on the 0.25 ha sampling areafrom each forest type are given in Figure 2. Schima wallichii–Lithocarpus fo-haiensis forest has a longer tail of the species sequence curve than other twoforest types, which indicates more species with only one or two individuals inthis forest type.

Discussion

Terminology for tropical montane forest types is not generalized. Montanevegetation zones in tropical America were classified into rain forest, lowermontane rain forest, montane rain forest, montane thicket and elfin woodlandwith increasing altitudes by Beard (1944, 1955). Similarly, Richards (1952)used the terms tropical rain forest, submontane rain forest and montane rainforest for the vegetation zonation in tropical montane zones. These tropicalmontane evergreen broad-leaved forests in southern Yunnan occur at thealtitudinal zone similar to the lower montane rain forest zone in tropical Asia(Whitmore 1984, 1990) and America (Grubb et al. 1963). Grubb and Whit-more recognized that tropical lower montane rain forests were usually 15–33 m tall and had two tree strata, few emergent trees, few trees with buttressesand cauliflory, few big woody lianas, fewer plants with pinnate leaves, butabundant epiphytes. These tropical montane evergreen broad-leaved forests insouthern Yunnan are fundamentally similar to tropical lower montane rainforests but differ in having more lianas, more plants with compound leavesand few epiphytes. This could be due to strongly seasonal climate by

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Table

4.

Lifeform

spectraofthesetropicalmontaneevergreen

broad-leaved

forestsin

southernYunnan.

Forest

type

Liana

Megaph

Mesoph

Microph

Nanoph

HPH

&Cha

HG

Total

Schim

awallichii–Castanopsishystrixforest

No.ofspecies

22

437

46

15

15

10

1150

%14.7

2.7

24.7

30.7

10.0

10.0

6.7

0.7

100.0

Schim

awallichii–Lithocarpusfohaiensisforest

No.ofspecies

28

634

41

15

23

97

163b

%17.2

3.7

20.9

25.2

9.2

14.1

5.5

4.3

100.00

Castanopsisechinocarpaforest

No.ofspecies

13

322

28

14

63

291

%14.3

3.3

24.2

30.8

15.4

6.6

3.3

2.2

100.00

Megaph.:Megaphanerophytes;

Mesoph.:Mesophanerophytes;

Microph.:Microphanerophytes;

Nanoph.:Nanophanerophytes;

Hph.:Herbaceousphan-

erophytes;Ch:Chamaephytes;H:Hem

icryptophytes;G:Geophytes.

aSomeherbaceousphanerophytescould

notbeclearlydistinguished

from

chamaephytes,therefore

weputthesetw

ocategories

together

inlife

form

spectra.

b1epiphyte

speciesexcluded.

2863

Table

5.

Leafsizesofthesetropicalmontaneevergreen

broad-leaved

forestsin

southernYunnan.

Forest

type

Nanophyll

26–225mm

2

Microphyll

226–2025mm

2

Mesophylla

2026–18225mm

2

Macrophyll

18226–164025mm

2

Total

species

Schim

awallichii–Castanopsishystrixforest

No.ofspecies

134

105

10

150

%0.7

22.7

70.0

6.7

100

Schim

awallichii–Lithocarpusfohaiensisforest

No.ofspecies

447

107

6164

%2.4

28.7

65.2

3.7

100

Castanopsisechinocarpaforest

No.ofspecies

227

60

291

%2.2

29.7

65.9

2.2

100

aWebb(1959)splitoffthelower

endofRaunkiaer’big

mesophyllclass

(2025–18225mm

2)asnotophylls(2025–4500mm

2).Itisbetterfordetailingcategory

of

leafsize

spectrum.However,Chinesebotanists

are

usedto

use

Raunkiaer’big

mesophyllclass,whichis

familiarto

ChinesereadersandhereIstilluse

Raunkiaer’big

mesophyllclass

forthetropicalmontaneforest

insouthernYunnan.

2864

monsoon in southern Yunnan and the so-called ‘Massenerhebung’, or masselevation effect (Whitmore 1990) because abundant lianas and plants withcompound leaves are characteristics of lowland tropical forest. The montaneforest in southern Yunnan is similar to tropical montane rain forests in SEAsia more in its floristic composition than its physiognomy. Both floristiccomposition and physiognomy is used as diagnosis in forest classification. It isbetter to use the term ‘tropical montane evergreen broad-leaved forest’ for thetype of montane forest in southern Yunnan in highlight its particular physi-ognomy.

The term ‘monsoon evergreen broad-leaved forest’ was used by some Chi-nese authors (Jin 1979, Wu 1987) for these montane forest types in southernYunnan. However, ‘‘monsoon forest’’ was commonly used for deciduous forestin strongly monsoonal climate zones in SE Asia (Schimper 1903). Thesemontane forests in southern Yunnan are evidently not monsoon forests of thesame type as in SE Asia because they are evergreen forests (deciduous treespecies are fewer than 10% of the total tree species). They are also differentfrom tropical lower montane rain forests in equatorial SE Asia due to a lack ofepiphytes and in having more abundant lianas and plants with compoundleaves. The term ‘tropical montane evergreen broad-leaved forest’ is suggestedhere for this type of forest in southern Yunnan because of its physiognomy,habitats and the confusion with the terms ‘monsoon forest’ and ‘tropical lowermontane rain forest’ of SE Asia.

Compared with tropical seasonal rain forests at lower altitudes in the region(Zhu et al. 1998a), these montane forests have fewer epiphytes, fewer mega-mesophanerophytes, fewer plants with compound leaves, but more abundantmicro-nanophanerophytes and hemicryptophytes, more plants with micro-phyllous leaves and more plants with entire leaf margins (Figure 3 and 4).

These montane evergreen broad-leaved forests also have conspicuouslylower species richness than tropical seasonal rain forests, which have Shannon–Wiener diversity indices varying from 3.1594 to 3.599 from the same areasampled (Zhu et al. 1998b).

Table 6. Leaf margins, leaf types and leaf habits of tree species from these tropical montane

evergreen broad-leaved forests in southern Yunnan.

Forest type Leaf

margin

Leaf type Leaf habit

E N S C EG D

Schima wallichii–Castanopsis hystrix forest No. of species 80 7 74 13 82 5

% 92 8 85.1 14.9 94.3 5.7

Schima wallichii–Lithocarpus fohaiensis forest No. of species 73 8 66 15 75 6

% 90.1 9.9 81.5 18.5 92.6 7.4

Castanopsis echinocarpa forest No. of species 50 3 38 15 48 5

% 94.3 5.7 71.7 18.3 90.6 9.4

E: Entire; N: non-entire; S: simple leaves; C: compound leaves; EG: evergreen; D: deciduous.

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In wet habitats in montane valleys and on some shady slopes at the samealtitudes as the tropical montane evergreen broad-leaved forests in southernYunnan, forests become more diversified in floristic composition and haveabundant epiphytes and herbaceous phanerophytes. These forests are muchmore similar to lower montane rain forest in equatorial southeastern Asia andtermed ‘tropical montane rain forest’ and treated as a subtype of tropical rainforest (Wu 1987). The tropical montane evergreen broad-leaved forests insouthern Yunnan, which occur in relatively dry montane habitats and areinfluenced by strongly seasonal dryness, could not be suitably classified into the

(a)

(b)

0.1

0.1

1

10

100

Speciessequence

1

10

100

Spicies sequence

Spicies sequence

Ste

ms

%(lo

gsc

ale)

Ste

ms

%(lo

gsc

ale)

Ste

ms

%(lo

gsc

ale)

(c)

0. 1

1

10

100

0 10 20 30 40 50 60

0 10 20 30 40 50 60

0 10 20 30 40 50 60

Figure 2. Rank/abundance diagrams of tree species from three forest types in southern Yunnan.

a: Schima wallichii–Castanopsis hystrix forest; b: Schima wallichii–Lithocarpus fohaiensis forest;

c: Castanopsis echinocarpa forest.

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category of either lower montane rain forest as in equatorial southeastern Asiaor the tropical montane rain forest occurring in wet valleys in southern Yun-nan. It is better to treat these tropical montane evergreen broad-leaved forests

0

5

10

15

20

25

30

35

40

45

50

LHSR RSR S-C S-L C

Forest types

Spe

cies

%

Ep

Lph

Mega-Mesoph

Micro-Nanoph

Hph + Ch

H

G

Figure 3. Comparison of life form spectra from tropical montane evergreen broad-leaved forests

and tropical seasonal rain forests in southern sYunnan. LHSR: Lower hill seasonal rainforest;

RSR: Ravine seasonal rainforest; S–C: Schima wallichii–Castanopsis hystrix forest; S–L: Schima

wallichii–Lithocarpus fohaiensis forest; C: Castanopsis echinocarpa forest. Ep = Epiphyte; Ch

= Chamaephytes; G = Geophyte; Lph = Liana-phanerophyte; H: Hemicryptophyte;

Hph = Herbaceous phanerophyte; Mega-Mesoph = Megaphanerophyte + Mesophanero-

phyte; Micro-Nanoph = Microphanerophyte + Nanophanerophyte.

0

10

20

30

40

50

60

70

80

LHSR RSR S-C S-L C

Forest types

Spe

cies

%

Nano-Micro.

Meso.

Macro.

Gigan.

Figure 4. Comparison of leaf size spectra from tropical montane evergreen broad-leaved forests

and tropical seasonal rain forests in southern Yunnan. LHSR: Lower hill seasonal rainforest; RSR:

Ravine seasonal rainforest; S–C: Schima wallichii–Castanopsis hystrix forest; S–L: Schima wallichii–

Lithocarpus fohaiensis forest; C: Castanopsis echinocarpa forest. Nano-Micro.: Nanophyll +

Microphyll; Meso.: Mesophyll; Macro.: Macrophyll; Gigan.: Gigantophyll.

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as a distinct vegetation type from the northern margin of mainland south-eastern Asia that is controlled by strongly seasonal climate based on theirfloristic and physiognomic characteristics.

These three forest types seem not identical in life form spectra, especially inthe mentioned categories of herbaceous plants. One explanation for the ob-served diversity is that these three forest types are in different successionalstages. Schima wallichii–Lithocarpus fohaiensis forest could be in more maturephase with more herbaceous plants, while Castanopsis echinocarpa forest ap-pears somewhat secondary with fewer herbaceous plants. Castanopsis echino-carpa forest has more deciduous plants and a higher ratio of trees with smalldbh (Table 7)). Schima wallichii–Castanopsis hystrix forest has more trees withlarger dbh than Schima wallichii–Lithocarpus fohaiensis forest but has fewerspecies and stems.

Acknowledgements

This project was funded by The National Natural Science Foundation ofChina (40271048), the Yunnan Natural Science Foundation (2002C0067M)and the Chinese Academy of Sciences – Yunnan province co-funded project2000 WK-7. Figure 1 was made by Dr. Hu Huabin. I thank Dr. Matthew W.Warren from University of Puerto Rico for his English grammaticalimprovements in my manuscript. I also thank reviewers very much for theirimportant and constructive comments.

Table 7. Distributions of trees in DBH classes of these tropical montane evergreen broad-leaved

forests.

DBH (cm) > 70 61–70 51–60 41–50 31–40 21–30 11–20 5–10

Schima wallichii–Castanopsis

hystrix forest

3 5 5 11 26 34 47 90

Schima wallichii–Lithocarpus

fohaiensis forest

1 1 3 9 31 56 133 146

Castanopsis echinocarpa forest 1 83 160 230

Table 8. Tree species diversity indexes based on 5 (25 � 20) sampling plots for each forest types.

Forest type No. of

species

No. of

Stem

Simpson

Index

Shannon–Winner

Index*

Schima wallichii–Castanopsis hystrix forest 36 221 0.923609 1.28662

Schima wallichii– Lithocarpus fohaiensis forest 46 380 0.963444 1.324883

Castanopsis echinocarpa forest 26 474 0.649638 0.753368

*Base: 2.718283.

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