On 2001 survey of medicinal plants in bavi national park

A survey of medicinal plants in BaVi National Park, Vietnam:
methodology and implications for conservation and sustainable use
Tran Van On
a
, Do Quyen
a
, Le Dinh Bich
a
, Bill Jones
b
, Josette Wunder
b
,
Jeremy Russell-Smith
c,
*
a
Hanoi College of Pharmacy, Viet Nam
b
Association for Research and Environmental Aid, Sydney, Australia
c
Parks Australia (now included within Environment Australia), Jabiru, Australia
Received 10 November 1999; received in revised form 20 June 2000; accepted 7 July 2000
Abstract
Conservation of medicinal plant resources is a critical ecologic, cultural and economic issue in Vietnam, as with other parts of
South-east Asia, and the tropics and sub-tropics generally. The paper describes the development and application of a survey
methodology, using standard phytosociological techniques, for the quantitative inventory of medicinal plants in BaVi National
Park, northern Vietnam. One hundred and twenty-six permanently marked transects, each 50 Â 10 m, were established over the
ranges of altitudes and characteristic vegetation structural types present in the Park. Over 200 medicinal plant species used by Dao
people were sampled (of a documented total of about 300 species including introduced species grown in home gardens), in vegeta-
tion types ranging from closed evergreen forest at high altitude (>1000 m), through secondary forest formations, bamboo thicket,

open grassland and plantation, distributed generally along a declining altitude gradient. Forty-one of 44 economically important
medicinal species were sampled also. Important medicinal plant species, half being vines, were concentrated particularly in more-or-
less intact, late secondary closed forest habitats at higher elevations. The status of most important medicinal plant species was
found to be rare or uncommon, and to exhibit scattered (as opposed to clumped) distributions. The paper discusses implications of
the applied methodology and the assembled data for the inventory, conservation, and sustainable use of medicinal plants at local
and broader regional scales. # 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Medicinal plants; Ethnobotany; Conservation; Inventory; Vietnam; South-east Asia; East Asia
1. Introduction
Considerable and growing attention has been given in
recent years to issues surrounding the in situ conserva-
tion, and ecologically- and economically-based sustain-
able use, of wild (i.e. undomesticated) populations of
medicinal plants (MPs) (e.g. Akerele et al., 1991; Plotkin
and Famolare, 1992; Balick et al., 1996). Most con-
servation focus has been given to individual, inter-
nationally and regionally economically signi®cant, over-
exploited MP species (Anon., 1995±1997). Nowhere are
these issues more acute as in tropical and sub-tropical
regions (e.g. Africa, the Americas, Asia), where still
today most people rely on medicinal, timber, and an
array of other non-timber vegetable/animal products,
derived principally from increasingly degraded, frag-
mented, species-diverse forest and savanna biomes (e.g.
Farnsworth and Soejarto, 1991; Toledo et al., 1992;
Iwu, 1996; Voeks, 1996; Caniago and Siebert, 1998).
Medicinal plant conservation has an extensive con-
temporary literature covering a range of subject areas.
Schippmann (1997) provides 590 references for the per-
iod 1990±1996, derived from over 50 relevant journals,
newsletters, and databases. This work covers, in ranked

thematic order, mostly: economic and trade aspects (181
entries); status and threat issues pertaining typically to
individual taxa (166); cultivation and harvesting issues
(120); regional/culturally focused ethnobota ny studies
(110 entries); species descriptions and identi®cation
(100); and policy and legislation issues, including intel-
lectual property rights (71). Most listed regional studies
0006-3207/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved.
PII: S0006-3207(00)00125-7
Biological Conservation 97 (2001) 295±304
www.elsevier.com/locate/biocon
* Corresponding author at Centre for Indigenous Natural and
Cultural Resource Management, Northern Territory University,
Darwin, Northern Territory 0909, Australia.
E-mail address: (J. Russell-Smith).
have focused on the Indian subcontinent, followed by
the Americas then China, with relatively few concerning
Africa and South-east Asia (Schippmann, 1997).
Few studies address, or provide regional empirical
examples of, quantitative ecologi cal survey (i.e. resource
inventory), sustainability, and associated database
designs. As noted by Hall and Bawa (1993), however,
the undertaking of ecological surveys focusing on the
distribution, abundance and population structures of
MPs is fundamental to the assessment of the conserva-
tion status of wild populations, and prerequisite for
addressing harvesting sustainability of key or target
species. Principles and guidelines concerning MP con-
servation database design, networking and main-
tenance, are outlined in Synge and Heywood (1991).

Toledo et al. (1992) provide a rare example of a national
MP database then under development for tropical forest
regions in Mexico, combining data from regional ethno-
botanical studies with plant species inventories undertaken
at a range of scales (e.g. sites, 4 1ha;localities, 1±10 ha;
regions, up to ca. 1000 ha).
In this paper, we describe the application of a standard
quantitative ecological survey design for assessment of
the distribution, abundance and status of MPs, as used by
the Dao ethnic group, in BaVi National Park, northern
Vietnam. The design has potential also for various
inventory, conservation, and sustainability assessment
applications at broader regional scales. As discussed
below, the assessment and conservation of MPs in Viet-
nam is a critical ecologic, cultural and economic issue in
that country; Schippmann (1997) lists just two Vietna-
mese references, and single references for neighbouring
Kampuchea and Laos. The project was undertaken col-
laboratively between the Vietnam National University
(Centre for Resource and Environmental Studies), Hanoi
College of Pharmacy, the Association for Research and
Environmental Aid (an Australian Non-Government
Organisation aid agency), and the Australian Nature
Conservation Agency (now included within Environ-
ment Australia).
2. Regional context and study area
Spanning the tropical, monsoon climatic zone, Viet-
nam has a high biodiversity with more than 10,000
described species of higher plants (Pham, 1999), of
which 3200 species have been recorded as having med-

icinal properties (Vo, 1997). However, with a high
population density and increasing demands for eco-
nomic development, Vietnam has lost more than 50%
of its forest cover over the past ®ve decades (Vietnam
Ministry of Science, Technology and Development,
1995). Current rates of deforestation of remnant dense
(>40% canopy cover) broad-leaved forests in Vietnam
are estimated to be >1% p.a. (Blasco et al., 1996).
Vietnam now faces over-exploitation of its plant
resources, including MPs. Given the importance of
native MPs in the domestic economy (Nguyen, 1996),
investigation of the conservation and sustainable use of
MPs in Vietnam is an urgent matter.
BaVi National Park is located generally between
21

01
H
±21
H
07
H
N and 105

18
H
±105
0
25
H

E in the BaVi Dis-
trict, Ha Tay Province, northern Vietnam, approxi-
mately 50 km north-west of Hanoi (Fig. 1). BaVi was
established as a National Park in 1992. The Park covers
an area of 7377 ha, including a Strictly Protected Area
(i.e. core area) above 400 m elevation of 3000 ha sur-
rounding three mountain peaks where there is still rela-
tively pristine tropical montane and semi-evergreen
forest (sensu Blasco et al., 1996) at higher elevations. The
Park is surrounded by a Particular Use Zone (i.e. buer
zone) of approximately 15,000 ha, previously under the
control of Park authorities but now falling under District
jurisdiction, but where a range of non-Park activities
(e.g. growing of crops, cattle grazing) is permitted. Alti-
tude ranges from 100 to 1296 m above sea level. Average
rainfall is 1660 mm, 90% of which is received during the
wet season months, June to October. Geology comprises
mostly ®ne-textured sedimentary rocks (AREA, 1993).
Towards the end of the nineteenth century, the
French botanist, Balansa, collected 5000 plant speci-
mens from the BaVi region. Recent investigations have
revealed more than 800 plant species, occurring in 427
genera and 98 families. At present the Park's ¯ora is
estimated to comprise 1500±2000 higher plant species
(Nguyen, 1990). Amongst the describ ed species are 13
local endemics (AREA, 1993), and 10 species recorded
in the Vietnamese Red Data Book for rare and endan-
gered plants (Tran and Tran, 1998). More than 30 0
local plant species ha ve been recorded as having medic-
inal value; a preliminary listing of these species is pro-

vided in AREA (1993).
There is a population of some 45,000 people, belong-
ing to Kinh, Muon g and Dao groups living in the Par-
ticular Use Zone (PUZ) of the Park. Outside the PUZ
population densities are high, with an estimated popu-
lation of around 15 million living in the Red River delta
lowlands, comprising 14,700 km
2
(Le and Tran, 1993).
Of the three ethnic groups, the Dao constitute the major
users of MPs in the Park, and this paper focuses on MPs
as de®ned and used solely by this ethnic group.
Shifting cultivation commenced in the mountainous
BaVi region as late as the 1920s when Dao people
migrated to the area. Since 1965, Dao people have been
resettled in the PUZ where they now reside in two main
communes consisting of about 2000 people. Transition
to a settled agricu ltural lifestyle has been dicult, how-
ever, and most Dao families continue to depend on
harvesting of natural resources to some extent at least.
Controlled harvesting of some natural products (fuel-
wood, fodder, medicinal plants and other vegetative
296 T. Van On et al. /Biological Conservation 97 (2001) 295±304
resources) is permitted in rehabilitation plantation
areas; regardless, illegal removal of both plant and ani-
mal resources continues throughout the Park. Dao
people daily collect and process substantial quantities of
MPs from the Park and its surrounds, both for domestic
and commercial purposes. Along with the cultivation of
cassava and other agricultural crops, the exploitation of

MPs constitutes a major economic acti vity. MP pro-
ducts are sold extensively by the Dao in surrounding
towns and communities (including the capital Hanoi),
for both wholesale and retail markets.
3. Methods
3.1. Medicinal plants
MPs used by Dao people were recorded in interviews
and participatory ®eld surveys, particularly with herb-
alists and collectors, over 2 years. Specimens of all MPs
were co llected during ®eld trips. One complete set of
reference specimens is lodged with the Herbarium of the
Hanoi College of Pharmacy (HNP).
Throughout the paper, reference is made to a subset
of MPs, the Important Medicinal Plant (IMP) species.
IMPs were identi®ed using standard Participatory Rural
Appraisal (PRA) techniques where herbalists were
asked to rank a list of regularly used local MPs com-
piled on the basis of extensive participatory ®eld obser-
vations. IMPs were determined on three criteria: (1)
proportion of herbalists using each listed species; (2)
frequency of use; and (3) market value. Details (and
results) of the applied PRA methodology, along with
information concerning the medicinal properties ascri-
bed to MPs by Dao herbalists, pro cessing techniques,
and other ancillary data, are not presented here but
form part of continuing studies being undertaken by the
®rst author as part of a PhD research program.
2.2. Vegetation habitats and medicinal plant survey
As a means for developing a habitat framework for
describing the distributions and ecologi cal relations of

MPs in BaVi National Park, 126 permanent transects,
each 50 Â 10 m, were established over the ranges of
altitudes and characteristic vegetation structural types
(primary and secondary forest, bamboo thicket, grass-
land, and plantation) present in the Park. Based on
advice provided by Dao informants, four of the above
transects were established speci®cally in areas known to
contain certain rare IMPs.
Vegetation data recorded at each transect included the
identi®cations and densities of all tree species (55cm
DBH), canopy height of the three tallest stems, bamboo
cover (%), other grass cover (%), and indices for canopy
cover [1=closed canopy (5 75%); 2=partial canopy;
3=open canopy (< 10%], and disturbance (1= primary/
intact forest; 2=secondary forest/thicket vegetation;
3=mostly cleared/replanted). Recorded environmental
data included altitude, slope, aspect, geology, water
Fig. 1. Location of BaVi National Park, Vietnam.
T. Van On et al. /Biological Conservation 97 (2001) 295±304 297
availability (0=a bsent; 1=seasonal; 2=permanent), and
slope position (1=valley bottom; 2=footslope; 3=mid-
slope; 4=topslope; 5=crest).
At each transect, the abundance of individual MP
species was recorded using the following scale: 1=1
individual present; 2=2±6 indivi duals; 3=7±20 indivi-
duals; 4=21±50 individuals; 5=51±100 individuals;
6=101±200 individuals; 7=201±500 individuals; 8=
>500 individuals. An estimate of the total abundance
of MP individuals occurring at an individual transect
was calculated by summing the maximum values possi-

ble for respective classes (e.g. 20 individuals for abun-
dance class 3) for all MP species sampled on the
transect.
3.2.1. Analysis
Preliminary analysis of the survey data was under-
taken using standard numerical pattern analysis techni-
ques incorporating classi®cation (i.e. grouping of
transects based on ¯oristic similarity) and ordination
(i.e. relative ordering along one to few dimensions, or
vectors, of transects based on ¯oristic similarity). While
a wide variety of classi®cation and ordination proce-
dures are available (e.g. see Gauch, 1982; Causton,
1988; Legendre and Legendre, 1998), we employed
widely used, complementary classi®cation (TWIN-
SPAN; Hill, 1979a) and ordination (Detrended Corre-
spondence Analysis (DCA); Hill and Gauch, 1980)
procedures based on reciprocal averaging (Hi ll, 1973),
contained in the simple-to-use, computationally e-
cient, DECORANA package (Hill, 1979b). While both
procedures have limitations (e.g. Knox and Peet, 1989;
Van Groenewoud, 1992), they aord generally eective
solutions especially where (as in this study Ð see
Results) vegetation patterning is under the in¯uence of
one dominant vegetation gradient and species' respon-
ses are predominantly unimodal (Peet et al., 1988;
Mucina and van der Maarel, 1989).
As a means for developing a habitat framework,
polythetic divisive classi®cation was undertaken with
TWINSPAN on a data matrix comprising 126 transects
 94 tree species (presence/absence) occurring in at least

®ve transects. Classi®cation was truncated at the third
division level, and yielded six readily interpreted trans-
ect groups (see Results). Complementary Detrended
Correspondence Analysis (DCA) ordination was
undertaken to derive transect scores for the ®rst two
vectors.
Using the six groups as a framework, subsequent
analyses involved: (1) calculation of group frequencies
for nominal (e.g. species occurrence) and ordinal (e.g.
slope position) variables; and (2) calculation of group
means and standard errors for measurement variables
(e.g. no. IMPs, stem density, altitude). To assist inter-
pretation of major trends in these data, a range of
environmental, vegetation structure, and MP data were
correlated (Pearson's r) with the ®rst two DCA vectors
derived from ordination of the matrix of 126 transects Â
94 tree species. Correlations were also undertaken
between MP variables and other environm ental and
structural variables, over all transects. All data manip-
ulation was performed with the DECODA package
(Minchin, 1990).
4. Results
4.1. Medicinal plants
A total of 207 MPs, of about 300 recorded in the
BaVi area (AREA 1993), were sampled in the 126
transects. Many of those unrecorded, however, occur as
exotics grown only in home gardens. Forty one IMP
species, of a total of 44 determined through the PRA
process, were sampled in transects; the three unrecorded
species are all considered to be very rare in the local

area by Dao herbalists. Of the 44 IMPs, three are grown
already in home gardens (Alstonia scholaris, Cinnamo-
mum zeylanicum, Tradescantia zebrina), and at least two
others could readily be grown (Piper retrofractum, Tra-
vesia palmata) from layered cuttings and seed, respec-
tively.
A listing of IMPs is provided in the Appendix A,
along with information concerning their lifeforms,
abundance in transects, and frequency of occurrence in
each of the six habitat groups derived through classi®-
cation (see below). Using these data we have classi®ed
the current occurrence of IMPs in BaVi National Park as
follows: (1) status, where occurrence in 1±2 transects=
rare, 3±9 transects=uncommon , and 10+ transects=
common; and (2) dispersion, where modal abundance in
transects of 1±6 individuals=scattered, and 7+ indivi-
duals=clumped. These data are summarised in Fig. 2.
Of note in Fig. 2 is that the status of over half the IMPs
is either rare or uncommon, and dispersion of the great
majority is scattered. Half the IMPs, including three
species not sampled in transects, are vines (see Appen-
dix).
4.2. Habitat framework
TWINSPAN classi®cation of a data matrix, compris-
ing 126 transects  94 tree species occurring in ®ve or
more transects, yielded six readily interpreted habitat
types (groups). The ®rst dichotomy separated 38 highly
disturbed and plantation transects all occurring at low
altitude, from other secondary and primary forest trans-
ects occurring up the mountainside. Plantation transects

(with very low tree species diversity Ð Group 6) were
distinguished from other open low altitude transects
(Group 5) in the se cond dichotomy. For the 88 transects
occurring at higher altitudes, two further divisions yielded
298 T. Van On et al. /Biological Conservation 97 (2001) 295±304
four site groups more-or-less neatly partitioned along
the altitudinal gradient as follows: a group of nine
transects comprising mostly undisturbed (primary)
montane forest vegeta tion atop the mountain peaks, at
a mean elevation of 1200 m (Group 1); 24 transects
comprising mostly disturbed, closed canopy, late sec-
ondary forest at a mean of 1000 m (Group 2); the
majority of transects (43) representative of partly
canopied, early secondary forest on midslopes, at a
mean of 650 m (Gr oup 3); and 12 transects representa-
tive of closed canopy, late secondary forest, associated
particularly with creeklines, at a mean elevation of 450
m (Group 4).
The frequency of occurrence of common tree species
(i.e. occurring at 10 or more transects) in each of these
six groups is presented as a sorted table in Table 1.
Means and modal values for a range of environmental,
vegetation structure, and MP variables, are given for
each of these groups in Table 2. Given that all transects
were found to be located on similar sedimentary parent
materials, substrate (geology) data are not included in
Table 2.
The predominant in¯uence of the altitudinal gradient
on the ¯oristic and structural patterning of vegetation
habitats in BaVi National Park is indicated by the

highly signi®cant negative correlation between altitude
and DCA scores for the ®rst vector (Table 3). This
interpretation is reinforced by: highly signi®cant nega-
tive correlati ons between DCA vector 1 scores and tree
species diversity per transect, and canopy height; and
corresponding highly signi®cant positive correlations
with disturbance, canopy cover, and grass cover indices
(Table 3). The second major axis of variation in these
data is evidently related to moisture availability (Table 3).
4.3. Distribution and abundance of medicinal plants
Whereas the complement of useful MP species occur-
red under all habitat conditions in BaVi National Park,
including in plantations and highly disturbed open-
canopy situations, IMP specie s were mostly restricted to
secondary growth and primary fores t conditions on the
mountainside and peaks, particularly between 600 and
1000 m elevation (Table 2). Overall, non-important MP
species were found mostly at lower elevations in typi-
cally disturbed habitats, and IMPs were found mostly in
relatively species diverse, undisturbed forest conditions
at higher elevations (Table 4).
MPs were most abundant in association with creek-
lines in late secondary forest vegetation at lower eleva-
tions (Group 4), then early secondary forests at
intermediate elevations (Group 3) and plantations
(Group 6), and least abundant at high elevations
(Groups 1 and 2; Table 2). Overall, MP abundance was
shown to be strongly negatively correlated with altitude
and better structurally developed forest habitat condi-
tions, and strongly positively correlated with relatively

disturbed, open-canopied, grassy situations (Table 4).
5. Discussion
5.1. Status of medicinal plant species in BaVi National
Park
Data presented here were derived from 126 transects
sampling just 6.3 ha, or 0.09% of the total area of BaVi
National Park. The sampling eort was not randomly
distributed; rather, plots were located mostly with
respect to a strati®ed design focusing on sampling major
habitats across the full altitudinal range. This resulted in
uneven sampling intensity over the Park area; for
example, 80 transects were used to sample vegetation in
the core area of the Park above 400 m, at a sampling
density approaching 0.13% . As well, some sampling
eort was intentionally focused on areas high on the
mountainside known to contain certain rare IMP spe-
cies. Despite these design limitations, it is evident that
assembled data aord useful insights into the distribu-
tions and `natural' habitat conditions of many indivi-
dual MP species, but especially the sub-set of naturally
occurring, culturally and economically IMP species.
The data indicate that while there was a substantial
MP resource base for Dao people occurring in BaVi
National Park, much of this was associated with species
occupying modi®ed, open-canopy habitats and planta-
tions, typically at lower elevations. Such disturbance-
adapted species, furthermore, presumably will continue
to be advantaged (in the short term at least) by ongoing
degradation of remaining forested areas. Prior to the
establishment of the Park in 1992, it was estimated that

Fig. 2. Relationship between status and dispersion of 44 important
medicinal plant species in BaVi National Park (refer to text for
details).
T. Van On et al. /Biological Conservation 97 (2001) 295±304 299
as much as 150 ha of forest habitat was being cleared
annually (Vietnam Ministry of Forestry, 1989) with the
result that probably as little as 1,500 ha of intac t forest
habitat remained by the early 1990s (AREA, 1993). In
modi®ed tropical settings many studies have noted the
singular importance of degraded secondary, and culti-
vated vegetation types as repositories of regional phar-
macopeia (e.g. Kohn, 1992; Toledo et al., 1992; Voeks,
1996). Species and structural diversity in tropical and
sub-tropical forests declines nevertheless with increasing
modi®cation (e.g. Whitmore, 1984).
In contrast, the great majority of IMP species were
found to be associated mostly with remnant, relatively
intact secondary forest formations at higher elevations;
however, at least 10 IMP species were recorded at least
once in substantially modi®ed habitats (Groups 5 and 6;
see Appendix), or were already being grown in home
gardens. Most remaining IMP species were found to be
rare or uncommon, occurring typically in dispersed
populations, and comprising a disproportionately large
number of vines. Given their domestic and economic
value, such species evidently are most at risk from
ongoing local exploitation. In the absence of remedial
attention, howeve r, the fate of IMPs may be likened to
that of vertebrates in the Park where, following surveys
conducted in 1962 and 1991±1992, it was concluded that

``mammal species richness in BaVi is poor, large mam-
mals have become locally extinct, small-medium size
mammals remain, but in small numbers'' (AREA, 1993,
p. 19).
Table 1
Sorted table of frequency of common tree and tall shrub species (occurring in 10 or more plots) in each of six classi®cation groups
a
Species code Group 1 Group 2 Group 3 Group 4 Group 5 Group 6
(n=9) (n=24) (n=43) (n=12) (n=9) (n=29)
Manglietia conifera 721
Eberhardtia aurata 75
Cryptocarya impressa 661
Litsea baviensis 7132
Meliosma longifolia 483
Antidesma fordii 4611
Tabernaemontana sp1 594
Syzygium sp5 113
Beilschmidtia balansae 281
Acer oblonga 284
Litsea balansae 21012
Ficus glandulifera 317202
Mischocarpus fuscescens 355 1
Tabernaemontana kwangsiensis 4511
Cylindrokelupha balansae 168
Knema corticosa 88
Adinandra integerrima 311
Claoxylon longifolia 1321
Helicia hainanensis 28112 1
Caryodaphnopsis baviensis 2796 1
Ostodes katherinae 720 1 1

Wrightia balansae 381
Saurauia tristyla 417 72
Trevesia palmata 153053
Scheera octophylla 1 2 15 1 3 4
Macaranga adenantha 210 1
Helicia sp362 10
Evodia meliaefolia 1522
Ficus fulva 110 22 1
Bischoa javanica 110 26 1
Saraca indica 210
Ficus hispida 637 6
Evodia lepta 11 1 1 21
Randia tomentosa 21 312
Rhus chinensis 111214
Mallotus philippensis 235
Breynia fruticosa 4318
Liquidamber formosana 1410
Ficus heterophylla 28
Acacia mangium 10
a
n=no. transects per group. Where given, voucher specimens as lodged at Hanoi College of Pharmacy (HNIP).
300 T. Van On et al. /Biological Conservation 97 (2001) 295±304
A critical issue facing conservation of the Park's
remaining biodiversity thus is to assist local commu-
nities develop alternative means for deriving or growing
natural products outside the Park. Such an approach
has been taken with the establishment of fast growing
timber species, albeit mostly exotic Acacia and
Eucalyptus spp., on land formerly cleared and in need of
rehabilitation. These endeavours have reduced the

extent of ®rewood removal from the Park, as well as
providing income for the local community through the
sale of thinnings, poles, etc.; further, as supply has
increased, the value of these products has decreased
markedly (AREA, 1993).
IMPs likewise are signi®cant in this regard. Challenges
have included developing eective, simple propagating
techniques, developing successful establishment regimes
in home garden situations (presumably requiring at
least wind-protection and semi-shade), appropriate
training, cultural acceptance, and ultimately, raising
awareness of the need for sustainable harvesting of
medicinal plant species in the wild. To these ends an
integrated program, involving over 200 herbalists and
farmers, was initiated in the PUZ of the Park in 1993
and completed recently. One of its priorities was to
encourage the cultivation of MPs as an agricultural crop
in home gardens, and to replant threatened species in
degraded areas of the Park as a regenerative strategy.
To date, 23 IMP species have been collected, propa-
gated (using simple, culturally appropriate techniques),
and successfully planted in trials under suitable habitat
conditions (e.g. initial protective shade) at several loca-
tions in the PUZ area.
5.2. Inventory, sustainab ility and regional MP
conservation
Both in Vietnam and in broader regional contexts,
there is an evident requirement for addressing the
conservation status of MPs and associated sustainability
issues, as there is for conserving biodiversity generally.

The Vietnamese population comprises at least 54 ethnic
groupings, most of whom depend heavily still on native
Table 3
Correlations between independent environmental, vegetation and
medicinal plant variables with vectors 1 and 2 from DCA ordination
of 126 transects  94 common tree species
Variable Vector 1 Vector 2
rP rP
Altitude À0.91 <0.0001 0.02 NS
No. tree species À0.85 <0.0001 À0.05 NS
Grass cover 0.81 <0.0001 À0.06 NS
Canopy height À0.80 <0.0001 À0.09 NS
Disturbance 0.74 <0.0001 À0.16 NS
Canopy cover 0.64 <0.0001 À0.12 NS
Slope À0.56 <0.0001 0.12 NS
No. important medicinal species À0.51 <0.0001 0.09 NS
No. other medicinal species 0.58 <0.0001 À0.19 NS
Abundance of medicinal plants
(all species)
0.54 <0.0001 À0.01 NS
Geology 0.14 NS 0.04 NS
Aspect 0.08 NS À0.13 NS
Stem density À0.56 <0.0001 À0.18 0.04
Slope position À0.33 <0.0001 À0.26 0.003
Water availability À0.10 NS 0.46 <0.0001
Table 2
Mean (Æ S.E.M.) and modal values of environmental, vegetation structure, and medicinal species variables, for six ¯oristic groups de®ned by
classi®cation of 126 transects  94 tree species occurring at ®ve or more transects
a
Variable Group 1 Group 2 Group 3 Group 4 Group 5 Group 6

(n=9) (n=24) (n=43) (n=12) (n=9) (n=29)
Environmental
Altitude (m) 1203Æ25 998Æ32 654Æ30 443Æ31 293Æ26 214Æ15
Slope (

) 36.4Æ4.7 38Æ3.3 32.5Æ2.3 21.6Æ3.5 18.5Æ4.6 18Æ1.6
Modal water availability Absent Absent Absent Present Absent Absent
Modal aspect North South/west North North East East
Modal disturbance class Primary Secondary Secondary Secondary Secondary Plantation
Modal canopy cover Closed Closed Half Closed Open Open
Modal slope position Topslope Midslope Midslope Creekline Lowerslope Lowerslope
Vegetation structure
No. tree species 20.6Æ1.8 20.7Æ1.2 13.9Æ0.8 6.5Æ14Æ0.5 1.7Æ0.4
Stem density (no./ha) 828Æ56 628Æ45 543Æ38 261Æ48 144Æ20 325Æ92
Canopy height (m) 27.8Æ2.7 23.1Æ0.7 18.9Æ1 11.6Æ1.2 8.3Æ1.4 6.1Æ0.7
Bamboo cover (%) 8.3Æ2.3 10.8Æ4.4 13.7Æ3 16.6Æ8.3 17.8Æ9.7 3.1Æ1.8
Grass cover (%) 0 0 8.2Æ2.4 22.5Æ8.9 35Æ8.6 60Æ5.5
Medicinal species
No. important medicinal species 3.4Æ0.6 5.6Æ0.9 5.4Æ0.4 3.6Æ0.8 0.8Æ0.3 0.4Æ0.1
Total no. medicinal species 8.1Æ1.0 11.3Æ1.3 14.9Æ0.9 9.3Æ1.1 13.9Æ2.6 13.3 1.0
Modal medicinal species abundance per transect 26±50 51±100 201±500 >500 101±200 201±500
a
n, No. transects per group.
T. Van On et al. /Biological Conservation 97 (2001) 295±304 301
MPs for domestic purposes. However, despite the
undertaking of qualitative inventories of MPs in various
parts of Vietnam over the past few decades (Le, 1997),
the development of quantitative, systematic approaches
remains, as elsewhere, elusive.
An objective of the present study has been the regio-

nal application of a standard numerical methodology
for assessing the distribution, abundance and status of
MPs. Such assessment is an essential ®rst step for
addressing the ecological sustainability of harvesting
Non-timber Tropical Forest Products (NTFPs), includ-
ing MPs (Hall and Bawa, 1993). For example, data
assembled here may be used in spatial an alyses [e.g.
using Geographic Information Systems (GIS)] to pre-
dict, hence map the probable distributions of MP taxa,
and ultimately derive baseline population estimat es of
target species. The statistical con®dence with which
spatial analyses are undertaken, however, obviously
depends especially on sampling intensity, and repre-
sentativeness/strati®c ation of plot locations.
Further, being digital, the database assembled for
BaVi National Park may be readily extended with
inventory data from other sampled locations (e.g.
within the Par k itself, other reserves, regions), including
surveys undertaken at dierent sampling times for
ongoing monitoring and sustainability assessment pur-
poses. Additionally, such digital data may be incorpo-
rated into other databases, thereby informing local
through to broader regional contexts. Once assembled,
such data sets are amenable for quantitative analyses
using a broad range of numerical tools and approaches
(e.g. Margules and Austin, 1991; Legendre and
Legendre, 1998).
While the compilation of numerical NTFP and MP
databases is evidently still in its infancy in south-east
and east Asi an contexts (Schippmann, 1997), quantita-

tive MP sampling approaches are evident, for example,
in the work of Toledo et al. (1992) for Mexico, Voeks
(1996) for disturbed Brazilian Atlantic forests, and
Caniago and Siebert (1998) for a localised study in
rapidly deforesting Kalimantan, Indonesia. A useful
regional model is provided also by a current, major
integrated MP conservation and resource development
project in Sri Lanka, which includes quantitative
assessment of the in situ conservation status and har-
vesting sustainability of MPs in four key national loca-
tions (World Bank, 1997). Such approaches have
broader regional potential.
Acknowledgements
We are extremely grateful to Professor Vo Qui and
Dr. Peter Bridgewater, and contributing organisations,
for the support and foresight to undertake this project.
Mr. Le Van Lanh and Mr. Phung Tien Huy assisted
with organising the initial ®eld program. Tracey May
produced Fig. 1. William Milliken and two anonymous
referees are thanked for their constructive comments on
the manuscript.
Table 4
Correlations between medicinal plant variables and other independent environmental and vegetation structure variables from 126 transects
a
Variable No. important medicinal species No. other medicinal species Abundance of medicinal species
rP rPrP
Grass cover À0.54 <0.0001 0.23 0.01 0.36 <0.0001
No. tree species 0.52 <0.0001 À0.32 0.0003 À0.39 <0.0001
Canopy height 0.49 <0.0001 À0.32 0.0002 À0.38 <0.0001
Disturbance À0.48 <0.0001 0.48 <0.0001 0.34 <0.0001

Altitude 0.37 <0.0001 À0.52 <0.0001 À0.55 <0.0001
Slope 0.35 <0.0001 À0.34 <0.0001 À0.27 0.002
Canopy cover À0.33 <0.0001 0.34 <0.0001 0.36 <0.0001
Stem density 0.22 0.01 À0.09 NS À0.28 0.002
Slope position 0.03 NS 0.03 NS À0.16 NS
Aspect 0.07 NS À0.03 NS 0.18 0.05
Geology 0.02 NS À0.03 NS 0.16 NS
Water availability 0.07 NS À0.29 0.0008 À0.05 NS
a
NS, not signi®cant, where =0.05.
302 T. Van On et al. /Biological Conservation 97 (2001) 295±304
Appendix
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