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© Hartmann, Barclay & Weipert: Biodiversität und Naturausstattung im Himalaya VII. - Erfurt 2021
Introduction
Issues of invasive plant species have become a global concern
and their spread is now recognized as one of the major threats to
biodiversity and human economic well-being. Invasive species
are often considered as the second greatest threat to biodiversity
conservation after habitat loss et al. 2018). In addition
to their ecological implications &,
-
nomic growth and food security (GISP 2009). Bhutan, with
the majority of the rural population depending on subsistence
farming is vulnerable to
the impacts of invasive species. Invasive species can result in
a yield loss of 25% in developing countries
in 2009, when more than 40 invasive plants were recorded in
Bhutan (NBC 2009). However, farmers’ perceptions towards
invasive species have not been appraised (NBSAP 2014). It has
than the direct negative impacts et al 2012) and farmers’
their preference and ability to use the species
Moreover, there is a growing consensus on the need for commu-
nity mobilization et al. 2009), education and outreach
initiatives et al. and an integrated approach to
managing IAS Therefore, this study was carried
out to understand the perceptions of farmers towards invasive
plant species and identify gaps to aid planners in formulating
Materials and methods
The study was conducted in Baap and Limbukha geogs (blocks)
under Punakha Dzongkhag (district) and Norbugang and Tas-
hicholing geogs under Samtse Dzongkhag. These Dzongkhags
were selected based on the presence of invasive plant species
the population of these Dzongkhags are agrarian farmers and
depend on agriculture, livestock, and forest for their livelihoods.
Hence, this area has been chosen for the current study. Baap and
22 respectively
(LCMP 2010) with elevations ranging from 1400 to 1800 metres
above sea level in a typical inner valley, with forest type ranging
from Chirpine to warm broadleaved forest. Norbugang and Tas-
hicholing geogs are located in the southern foothills of Bhutan
2 respectively (LCMP
2010). The altitude ranges from 400 to 1400 metres above sea
level, and is dominated by subtropical broadleaved forests.
each Dzongkhag. The number of households required for sam-
pling was determined using Yamane formula, n = sample size,
N = population size, e2 = error of sampling We
selected the households by generating random numbers in Micro-
and semi-structured interview based on the questionnaire adopted
from et al (2012) -
tistical Package for Social Science (SPSS) version 22 were used
Descriptive analyses such as frequency distribution were used to
describe the demographic characteristics, general awareness, and
arrival, spread and factors of spread, and the control of invasive
plant species. Pearson’s Chi-square Test for Independence was
conducted to see the relation between Dzongkhag and the impact
of invasive plant species on people’s livelihoods and the need for
support from government in managing invasive species.
Results
General awareness of invasive plant species
Data were collected from 291 respondents, spanned across four
geogs in two Dzongkhags. Out of 154 respondents from Puna-
with the oldest respondent age of 80 and the youngest of 19. Of
±
Perception of farmers towards Invasive Alien Plant Species: A case study from Punakha and
Samtse Dzongkhags, Bhutan
&
Abstract
We conducted a study to evaluate the perception of farmers towards invasive plant species, and the impact of invasive plants on local livelihoods in Punakha
total of 11 invasive plant species were recorded. Invasive species posed the greatest threat to agricultural land, and reduced crop production. The impact of
Invasive Alien Species (IAS) on the livelihood of people is more prominent in Samtse than in Punakha, mainly because of Lantana camara and Mikania
micrantha
integrated and adaptive management.
Key words: Bhutan, invasive plant species, farmers, Eastern Himalaya
90
Hartmann, M.; M.V.L. Barclay & J. Weipert: Biodiversität und Naturausstattung im Himalaya VII
the farmers interviewed were familiar with invasive plants, and
previously. There is a perception that IAS are now increasing.
A total of 11 IAS plants were recorded and are further detailed
in Table 2 (Photo 1 & 2). These include three of the 100 most
invasive species In addition, the respondents
Fig. 1. Map showing the study areas
Table 1: Count of general awareness on invasive plant species (percentage in parenthesis)
Dzongkhag
Punakha Samtse
Are you familiar with IAS? Well known
General 0 (0)
Little 0 (0)
Have you observed IAS in your area? Yes
No 0 (0)
First observation of IAS (years previously)
<5 0 (0)
0 (0)
>11
What is the trend of IAS?
Increasing
Decreasing 0 (0) 0 (0)
No change 0 (0)
No answer 0 (0)
91
Photo 1. Invasive Alien Plant Species. A) Ageratum conyzoides Ageratina adenophora infestation in Punakha (Photograph:
Tshering Dorji, 2012). C) Flower of Bidens pilosaChromolaena ordorata (NBC, 2012). E) Lantana camara (Pho-
Mikania micrantha growing on trees (Photograph: Tshering Dorji, 2014). G) Flower of Mimosa pudica (Photograph:
Opuntia vulgaris
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Hartmann, M.; M.V.L. Barclay & J. Weipert: Biodiversität und Naturausstattung im Himalaya VII
Punakha and Samtse each have seven invasive plant species,
with four species in common. Cannabis sativa, Opuntia vul-
garis, Parthenium hysterophorus, and Trifolium repens are
found only in Punakha. Similarly, Lantana camara, Mikania
micrantha, and Sida acuta are recorded only from Samtse.
IAS appear to occur more in disturbed areas with human in-
terference. While most species are distributed across a wide
range of habitats, Ageratum conyzoides and Trifolium repens
Mimosa pudica
appears to be more ubiquitous and perceived as problematic
in Samtse more than in Punakha.
Impact of invasive species on livelihood and wellbeing
Almost all the farmers shared that IAS were problematic.
species on their livelihoods and wellbeing. More than 95%
felt that the IAS were problematic to agriculture. 48.91 % of
the respondents from Samtse shared that IAS cause problems
to their livestock. Only 2 respondents from Punakha reported
that IAS caused problems in the forest in the form of reduced
grazing area. IAS cause a reduction in crop yield and are a
Photo 2. Invasive Alien Plant Species. A) Cannabis sativa (Photograph: Phuentsho, 2015). B) Trifolium repens (Photograph: Tshering Dorji, 2012). C)
Parthenium hysterophorus (NBC, 2008). D) Sida acuta Chromolaena ordorata infestation (Photograph: Tshering
Dorji, 2012). F) Mikania micrantha
The chi-square test on the impact of IAS on the livelihood be-
2 (1, N = 291) = 112.22,
p < .01. The impact of IAS on the livelihood of people is more
pronounced in Samtse (100%) than in Punakha (42.9%). In
Samtse, Lantana camara Mikania micrantha were
given the highest impact rating followed by Mimosa pudica
and Paspalum conjugatum. Other minor impacts are caused
by Ageratum, Cynodon, Ageratina Chromolaena (28).
Contrastingly, in Punakha Potamogeton distinctus, Cynodon
dactylon, and Bidens pilosa were given the highest impact
rating. Monochroa vaginalis, Cyperus diormis, Cynodon
dactylon, Paspalum distichum, Galinsoga parviora, Bidens
reported to be poisonous to cattle. This shows that invasive
plant species are not a good source of fodder. Respondents
shared that Parthenium causes skin and nose allergies.
Uses of invasive species
Although in the South Asian region, local communities derive
many uses from IAS et al. ), they
the population in Punakha shared that Opuntia vulgaris is an
Table 2: Occurrence of invasive species, with distribution denoted by a (Punakha), b (Samtse), and ab (both).
Species Occurrence
Ageratina adenophora ab
Ageratum conyzoides ab
Cannabis sativa a
Chromolaena odorata ab
Lantana camara b
Mikania micrantha b
Mimosa pudica ab
Opuntia vulgaris a
Parthenium hysterophorus aDisturbed forest, roadsides,
Sida acuta b
Trifolium repens a
Table 3.
Rank Punakha Samtse
1Potamogeton distinctus, Cynodon dactylon, Bidens pilosa, Lantana camara, Mikania micrantha
2Kamyue, Ageratina adenophora, Oxalis cuneata Mimosa pudica
Cyperus diormis, Acmella uliginosa, Echinochloa crus-galli Ageratina adenophora, Paspalum conjugatum
4Monochroa vaginalis, Parthenium hysterophorus Ageratum conyzoides, Cynodon dactylon
5Chromolaena odorata, Galinsoga parviora Chromolaena odorata
Fig. 2. Impact of invasive species on farmers in two Dzongkhags
pilosa, Ageratina, Partheni-
um, Chromolaena, Ageratum,
Carex, Cannabis sativa, Sida
acuta and Trifolium repens
appear to be relatively less
of a nuisance as agriculture
weeds.
Apart from their implications
for agriculture, a few invasive
plant species are reported to
impact human and animal
health. In Samtse, Lantana
camara-
ic to cattle. Similarly, respon-
dents from Punakha shared
that Parthenium hysteropho-
rus, Ageratina adenophora,
and Chromolaena odorata are
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Hartmann, M.; M.V.L. Barclay & J. Weipert: Biodiversität und Naturausstattung im Himalaya VII
Arrival and spread of invasive species
It appears that most of the IAS have been present for some time
observed for at least 11 years. IAS arrival is earlier in Samtse
years for all species. Respondents shared that Cannabis sativa
and Mikania micrantha are among the earliest arrivals, and
have been present for more than 50 years. They are followed by
Opuntia vulgaris, Sida acuta. Chromolaena odorata, Agerati-
na adenophora and Ageratum conyzoides arrived at the same
time. The most recent arrival is of Parthenium hysterophorus.
and Mimosa pudica (42%, n = 58). Ageratina adenophora
ChromolaenaAge-
ratum conyzoides
Respondents were asked about the factors contributing to the
introduction and spread of invasive alien plants (Figure 1).
from contaminants in herbicides and chemical fertilizers. Plants
have also been introduced deliberately, and by developmental
activities and increased human and vehicle movement. These are
then spread by wind, water and by animals as a result of grazing.
Only two respondents shared the opinion that it may be due to
climate change and the invasive nature of the plants themselves.
However, in Samtse, the majority of the respondents felt that
IAS are spread due to movements of animals. Of these, live-
stock grazing appears to be the major factor (59%) followed by
birds and insects (15%). Unlike in Punakha, no respondents re-
ported casual introduction to be the cause. It is also interesting
to note that the percentage of respondents reporting chemical
fertilizer is considerably lower than in Punakha.
Control of invasive plant species
Table 4: Uses of invasive species with percentage of households in parentheses
Species Use
Opuntia vulgaris
Mikania micrantha Cattle bedding (14)
Chromolaena odorata Cattle bedding (10)
live fencing (Table 4). Mikania micrantha and Chromolaena
odorata are apparently used as cattle bedding. One of the re-
spondents shared that Mikania is used for medicinal purposes.
In general, farmers percei-
ve invasive plant species to
be either rapidly increasing
-
Parthenium hysterophorus
the most rapid increase over
the years, followed by Age-
ratum conyzoides
Opuntia and Trifolium
do not appear to be as inva-
sive as others, and their rate
of increase is also reported
to be slower than the other
invasive species. In Samtse,
Mikania
rapidly increasing, followed
by Lantana
Fig. 3.
Fig. 4.
The control of invasive plants
With the overwhelming majo-
rity of respondents indicating
them to be problematic, and ef
-
forts have been carried out to
contain them through weeding
and uprooting, and with herbi-
cides. A few wetland-holding
respondents shared that straw
-
trol invasive species. However,
reported that these measures
shared that these measures
provide only temporary relief.
95
In most cases, successes are only seasonal thus requiring
annual control. Few respondents shared that such measures
are only a waste of resources. As in Nepal, these measures
are self-initiated.
There appears to have been little impetus from the Govern-
ment on controlling invasive plant species. About 80% of the
respondents felt that that the government should intervene
and support them in controlling IAS. A chi-square test was
performed to see the likelihood of response for support from
the government between Dzongkhags. The relation of these
2
People from Samtse (100%) were more likely to say they
There is an overwhelmingly high response on the support in
-
tervention on Potamogeton distinctus and Kamyue sp. and
Cynodon dactylon
need for chemical herbicides to suppress IAS, which are
eco-friendly and do not impact soil nutrition. Respondents
Lantana camara. Only
one respondent suggested control measures to eradicate IAS
from the forest. Similarly, only one respondent suggested
timely monitoring.
Discussion
Although the initial arrival date of invasive species is not
known, herbarium records suggest that they were present as
of humans around the world has facilitated intentional and
accidental transportation of species and facilitated invasions
et al. 2009). It may be hypothesized that the en
-
try of invasive species may from India through cross-border
movement. While further studies may be required, our study
supports this suggestion, as most of the invasive species show
a consistently earlier entry in Samtse Dzongkhag that shares
its border with India. Many invasive species in Bhutan are the
result of deliberate introduction or imported as contaminants.
People usually perceive invasive plant species based on how
they impact their livelihoods It is evident
that the farmers’ perception is that the main impact of invasive
species is on agriculture. This could indicate that farmers are
relatively less reliant on forest products. The general percep-
tion of the impact of invasive plants could be proportionate
to the level of use by the local communities. The impact of
IAS on the livelihood of people is more pronounced in Samtse
than in Punakha. There is an overwhelmingly high response
to support in the form of herbicide.
et al. (2012) and argue that invasive plant
species do not needed to be regarded as negative to people.
Farmers adapt to these new invasions and make use of them.
In Nepal, invasive species are now being used by local people
ornamental and habitat restoration et al. 2005). An
ecosystem-based adaptation is being piloted in Nepal, Peru and
Table 5: Perceptions of control measures against IAS
Dzongkhag
Punakha Samtse
Are the measures successful? Yes 0 (0)
No
Temporary 80 (51.95)
Do you feel the govt. should support? Yes
No 0 (0)
Fig. 5.
Uganda to build community
resilience &-
While similar ini-
tiatives can be emulated in
Bhutan, farmers are generally
use of invasive species.
Conclusion
People usually perceive IPS
based on how they impact
their livelihoods -
Through this stu-
dy, the overriding emphasis
on invasive plant species
from the point of view of ag-
Hartmann, M.; M.V.L. Barclay & J. Weipert: Biodiversität und Naturausstattung im Himalaya VII
riculture is evident. However, it must be noted that farmers in
Punakha perceive native weeds as more important than IAS.
The impact of invasive plant species is particularly prominent
in Samtse. With most of our trade with India, the natural entry
route of IAS to Bhutan is through India. Samtse, which shares
its borders with India, consistently showed an earlier mean date
IAS through weeding and uprooting, and the use of herbicides.
In most cases, successes have only been only seasonal, thus
requiring annual control, in the absence of a national strategy
and lack of resources. Although invasive species having been
present for over three decades, the use of these species is
minimal. There is a need for proper management strategies
integrated and adaptive approach. Invasive plant species are
now an important economic resource for many communities
et al. 2012). While this should not be considered an al-
ternate management option, this could provide avenues for an
incentivized mechanism for mobilizing communities towards
sustainable management of invasive species. Feasibility stu-
dies for producing vermicomposting, bio-gas and furniture are
that most farmers are unaware of the impact of invasive species
on the ecosystem. Additionally, a socio-economic impact study
needs to be carried out. Awareness needs to be raised among
local people focussing on the impacts on the ecosystem, their
role in management, and possible areas for utilization.
Acknowledgement
The authors would like to thank Dr. Tashi Yangzome Dorji,
former Program Director of the National Biodiversity Centre
for her guidance in carrying out this study. We also would
like to thank all the farmers involved or interviewed during
this study period.
References
(2012): Country Diagnostic Studies: Bhu-
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& The role played by invasive
species in interactions with endangered and threatened species in
the United States: a systematic review. - Biodiversity and Conser-
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GISP (2009)
Cape Town South Africa. http://www.gisp.org/.
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ment challenges of Mikania micrantha invasion in Chitwan Nati-
3 (4):
e00289. 2-14.
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Kaski: An Ecosystem-Based Adaptation in Mountain Ecosystem in
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the world's worst invasive alien species: a selection from the global
Specialist Group. 1-10.
&eds.) (2019): Communi-
ty-based Control of Invasive Species. - CISRO Publishing. 1-280.
& ): The evolutionary impact of
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NBC (2009): Invasive plants of Bhutan (Unpublished report). - National
Biodiversity Centre, Ministry of Agriculture and Forests, Thimphu,
Bhutan.
NBSAP (2014): National Biodiversity Strategies and Action Plan. - Na-
LCMP (2010). Landuse Cover Mapping Project. - National Soil Service
Centre, Ministry of Agriculture and Forests, Royal Government of
& A framework for ma-
nagement of Lantana camara in India. -.Proceedings of the Inter-
national Academy of Ecology and Environmental Sciences 3 (4):
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from South Africa. - Human Ecology 35
Biological control. - In: R. S. & K. L.
(eds): 50 Years of Crop Science Research in India. - Indian
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Authors addresses:
Tshering Dorji
Department of Forests and Park Services
Ministry of Agriculture and Forests
Thimphu, Bhutan
tdorji1@moaf.gov.bt (corresponding author)
Rinchen Yangzom
Kencho Dorji
Rinchen Dorji
Choki Wangmo
Choki Gyeltshen
National Biodiversity Centre
Ministry of Agriculture and Forests
Serbithang, Thimphu, Bhutan
Dago Dorji
Department of Forests and Park Services
Ministry of Agriculture and Forests
Bhutan
ddorji@moaf.gov.bt
Annexure 1: Important weeds in agriculture land in Punakha and Samtse.
Species Family Punakha Samtse
Acanthospermum hispidum Asteraceae +
Acmella uliginosa Asteraceae +
Alternanthera sessilis Amaranthaceae +
Amaranthus hybridus Amaranthaceae +
Avena fatua Poaceae +
Artemisia sp. Asteraceae +
Bothriochloa bladhii Poaceae +
Bidens pilosa Asteraceae +
Carex licinia Cyperaceae +
Centella asiatica Apiaceae +
Cynodon dactylon Poaceae + +
Cyperus diormis Cyperaceae +
Datura stramonium Solanaceae +
Drymaria cordata Caryophyllaceae + +
Echinochloa crus-galli Poaceae + +
Galingsoga parviora Asteraceae + +
Girardinia diversifolia Urticaceae + +
Hydrangea macrophylla Hydrangaceae +
Kyllingia brevifolia Cyperaceae +
Monochroa vaginalis Pontederaceae +
Oxalis cuneata +
Paspalum conjugatum Poaceae + +
Persicaria runcinata Polygonaceae + +
Potamogeton distinctus Naiadacea + +
Rumex nepalensis Polygonaceae +
Schoenoplectus juncoides Cyperaceae +
Stellaria media Caryophyllaceae +
Spermacoce alata Rubiaceae +
Tagetes minuta Asteraceae +
Tephrosia candida Leguminosae +
Urtica dioica Urticaceae +
Vicia hirsuta Leguminosae +
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Hartmann, M.; M.V.L. Barclay & J. Weipert: Biodiversität und Naturausstattung im Himalaya VII
Annexure 2 (Questionnaire)
Name of respondent: Age:
Geog: Dzongkhag:
1. Are you familiar with invasive plant species?
Well known
General
Little
2. Have you observed any invasive plant species in your area/ region?
Yes
No
………………………………………………………………………………
Less than 5 years
More than 11 years
5. Do you think invasive plant population is increasing or diminishing where you observed?
1....................................................................................................................................................................................................
2....................................................................................................................................................................................................
....................................................................................................................................................................................................
4....................................................................................................................................................................................................
5....................................................................................................................................................................................................
9. What are the factors responsible for introduction and spread of invasive plants?
a) Grazing c) Climate change
g) Through intorduction of species
b) Population growth d) Forest degradation f) Deleopment activities h) Other
10. Please give us some plants/animals that are particularly threatened by invasive plant species
11. Where are they abundantly seen?
12. Their spreading rate in your area/ region/geog?
..............................................................................
14. Are you aware of any other impacts of these plant species to human health and livestock? ................................................
15. Are you aware of any local beliefs associated with any of these species? (Please List them) .............................................
.....................................................................................
..........................................................................
18. Do you feel it is necessary for the government to intervene in controlling these species?
Yes
No
19. What kind of help and support is you willing to give if the government is going to intervene?
