Impact of Mikania micrantha invasion and perceptions of local communities in Central Nepal

ABSTRACT

Mikania micrantha, one of the most widespread and problematic invasive alien species, has a negative impact on ecology and people’s livelihood. Though numerous studies have focused on ecological consequences, limited research has addressed the socio-economic impact of this weed. Using a case study from a buffer zone community forest in the Chitwan district, central Nepal, this paper assessed the impact of M.micrantha invasion on livelihood and explored coping strategies adopted by local communities. Household interviews, focus group discussions, and key informant interviews were employed to collect qualitative and quantitative data. The results indicated that the invasion of M.micrantha resulted in decreased availability of preferred wild edible vegetable species, such as Matteuccia struthiopteris (Nuiro) and Asparagus officinalis (Kurilo). Local people’s perception towards the introduction, application, and coping strategy for M. micrantha significantly differed with distance to the forest, type of residents (native vs. migrants), and other demographic characteristics (e.g. age and caste). Local people perceived that invasion affected the wildlife habitat and decreased the availability and quality of native tree species, resulting in additional travel distances to collect forest products. Factors like forest closure, seed dispersal, and lack of management caused increased invasion whereas natural process, mechanical intervention, and silvicultural operation facilitated reduced invasion. Although the community forest user group intervened to control the invasion, their efforts were ineffective in managing and controlling invasive species due to poor institutional support. Collective actions among the government, non-government organizations, and the local community would increase effectiveness in reducing the negative impact of this weed.

KEYWORDS:

• Community Forest
• Invasive Alien Species
• Livelihood
• Mikania micrantha
• Perception

1. Introduction

Invasive alien species (IAS) have been identified as a threat to ecosystems and biodiversity (Blackburn et al., 2019; Najberek et al., 2022) and can lead to severe socio-ecological problems in forests, wetlands, and agricultural land around the world (Liu et al., 2020). Species, that have been relocated deliberately or accidentally with the expansion of global trade and increased human mobility, and negatively affect the growth of other species, are known as IAS (Holmes et al., 2009; Meyerson & Mooney, 2007). However, not all those species are IAS. The Intergovernmental Platform for Biodiversity and Ecosystem Services (IPBES) reported that approximately one-fifth of the total surface of the earth, including biodiversity hotspots, is at risk of invasion by IAS, and this number doubled over a 50-year period (IPBES, 2019). Situated in the heart of the Himalayan biodiversity hotspot, Nepal has experienced a significant influx of IAS (Shrestha, 2019). Furthermore, the proliferation of these IAS is expected to escalate in both scope and impact (Shrestha et al., 2019).

M. micrantha, also known as the ‘mile-a-minute weed’ due to its rapid growth rate and great sexual reproductive capability, belongs to the Asteraceae family and is one of the top 100 problematic invasive species globally (Liu et al., 2020). Originating in central and southern America, it has been documented across Asia, Papua Guinea, Pacific Ocean Islands, and the United States. M. micrantha can quickly sprout from runners and suckers as well as regenerate from stem fragments after manual or mechanical slashing (Day, 2022). The flowers, each 3–5 mm long, are arranged in dense terminal or axillary corymbs (Ram, 2008). The biomass of the flower accounts for 38.4% − 42.8% of plant biomass during the sexual reproduction period. The seed is black, linear-oblong, five-angled, and about 2 mm long (Ram, 2008). M. micrantha reproduces sexually through tiny seeds (1000 seeds weighing 0.0892 g), ideal for wind dispersion (Zhang et al., 2004). The germination rate of seeds in the spring is slightly greater than in the fall (80% vs. 70%), suggesting that M. micrantha seeds require after-ripening (Zhang et al., 2004).

A total of 219 types of naturalized alien plant species have already been discovered in Nepal, with 25 species reportedly threatening native biodiversity in various ecosystems (Thapa et al., 2014). M. micrantha is among these species and is listed as one of Nepal’s 21 most problematic IAS (Tiwari, 2005). Originally discovered in Nepal’s eastern region in the early 1960s, M. micrantha is now expanding westward through the Terai and Siwalik region, posing a major threat to the protected areas (Tiwari, 2005). This species spreads rampantly across the forest canopy, obscures sunlight, and destroys or stunts the growth of native plants (MoFSC, 2014). For example, an exponential growth rate of this plant has severely impacted nearly 50% of the core area of the forest, grassland, and wetland in Koshi Tappu Wildlife Reserve (Siwakoti, 2007). Besides forest and agricultural environments, M. micrantha affected other ecosystems like the wetland ecosystem. It blocks sunlight, obstructs oxygen supply to marine biodiversity, and disrupts the ecological balance of the aquatic ecosystem affecting aquatic flora and fauna (Baral & Adhikari, 2017). The widespread growth of the weed has severe consequences for wildlife populations including birds (Baral, 2002). Likewise, it has affected over 20% of the area in Chitwan National Park (CNP) (Khadka, 2017), significantly reducing the biomass production of one-horned Rhino’s (Rhinoceros Unicornis) food plants and making it a most serious weed in the CNP (Murphy et al., 2013). The presence of M. micrantha has detrimental effects on rural ecosystems by decreasing the availability of locally important ecosystem services (Rai & Scarborough, 2015). Despite an increasing invasion of M. micrantha in Nepal, particularly near protected areas and buffer zones, fewer efforts have been made to control the invasion, leading to the degradation of the buffer zone environment in terms of biodiversity and household livelihoods (Rai et al., 2012b).

Forests provide diverse ecosystem services that form an integral part of the livelihood of the rural population. Therefore, a reduction in ecosystem services due to IAS can have a serious impact on the well-being of the people (Bhattarai et al., 2020). The rural population in Nepal depends on agriculture for their daily livelihood; however, studies suggested that M. micrantha can reduce crop productivity and increase weed control costs pushing people toward poverty (Adhikari et al., 2004; Day et al., 2016; Pandit & Bevilacqua, 2011; Tiwari et al., 2005).

IAS are often integrated into the local livelihoods because they were intentionally or unintentionally introduced into the local ecosystem, leaving communities with limited options other than using or living with these species (Shackleton et al., 2007). While some IAS can be beneficial to some people, they can be hazardous to others. Furthermore, some IAS have significant negative consequences that increase vulnerability in a social-ecological system (Shackleton et al., 2019).

The effect of IAS on rural communities is much more complex than the negative ecological consequences alone (Khadka, 2017). People’s livelihoods are negatively affected by IAS in different ways. For example, IAS invasion influenced the growth of agricultural crops and forests causing economic loss (Shackleton et al., 2007, 2019). Social factors and processes are crucial for environmental management and conservation as humans are central in shaping and responding to the processes of environmental change (Bennett et al., 2017). While the ecological impacts of IAS are well-documented (Najberek et al., 2022; Pyšek et al., 2020; Sumerall, 2007), there are comparatively fewer studies exploring their role on the local livelihood globally (Shackleton et al., 2007, 2019). As individuals perceive the environment and address life challenges differently based on their attributes, socioeconomic characteristics, and institutional and policy context (Shackleton et al., 2019), more research is required on communities’ perceptions to make invasive species management programs effective (Seid et al., 2020). However, the majority of the research conducted in the country focused on ecological aspects, neglecting local livelihoods (Aryal et al., 2018; Baral & Adhikari, 2017; Murphy et al., 2013; Siwakoti, 2007). Therefore, local peoples’ perception of invasive species is important to devising policies, ensuring effective implementation, and gaining wider acceptance, especially for developing countries like Nepal, where local peoples’ engagement is crucial for natural resource management. In this context, this study identified and explored people’s perception towards the invasion of M. micrantha, its impact on the local livelihood and the environment, and coping measures adopted by the local people. This study addressed the following research questions:

1. What are the factors influencing people’s perception of the invasion of M. micrantha?

2. In what ways does the invasion of M. micrantha affect the local livelihoods of the local people?

3. What measures have the local people adopted to cope with the challenges posed by the invasion of M. micrantha?

The study provides important input in devising a mechanism to manage M. micrantha and reduce possible risks of invasion in the newly invaded and potential geographic areas at risk for invasion.

2. Materials and methods

2.1. Study area

The study was carried out in Kumroj Buffer Zone Community Forest located in the buffer zone of Chitwan National Park (CNP), Nepal. Established in 1973, CNP is located in the south-central lowland of Nepal, between 84°20” east and 27°30” north, with an area of 952.6 km² (Figure 1). This park is a renowned biodiversity hotspot and a UNESCO World Heritage Site (DNPWC, 2010).

Map of the study area showing Kumroj Buffer Zone Community Forest in the bufferzone of the Chitwan National Park, Nepal.

The primary forest type in the study area is riverine, comprising species such as Bombax ceiba, Dalbergia sissoo, Acacia catechu, and Trewia nudiflora. Among these species, Trewia nudiflora‘s fruits are the most crucial food source for Rhinoceros unicornis, a critically endangered species according to the IUCN red list criteria (Sujakhu et al., 2009).

Kumroj forest was selected because the forest was highly invaded by M. micrantha, affecting the ecology and livelihood of the local people after consultations with CNP officials, the buffer zone management committee, and local stakeholders. The total area of this forest is 697 hectares, supporting 2,109 households and 8,082 populations of diverse castes and ethnicities comprising indigenous Tharu and Damai communities along with hill migrants (CNP, 2019). The majority of people depend on agriculture and forest resources to fulfill their livelihood needs (Khadka, 2017). M. micrantha, is rapidly spreading through forest patches and grasslands in the buffer zone of CNP (Sapkota, 2007). The impact of M. micrantha‘s colonization on native plant species in the CNP buffer zone of Nepal has been well documented (Rai et al., 2012a; Sapkota, 2007).

2.2. Data collection

Data were collected using various participatory methods including household surveys (N = 150), focus group discussions (FGD) (N = 4), and key informant interviews (KII) (N = 4). A preliminary survey was carried out in February 2020, which involved stakeholder consultation, study site selection, and testing of questionnaires for the household survey. After making necessary modifications to the questionnaire, the semi-structured questionnaires including both open and close-ended questions were prepared, and the survey was administered. Field observation, FGD, KII, and household surveys were executed in March 2020 for 16 days. Stratified random sampling was used to select the households based on their distance from the forest area. Consent was taken before taking interviews with the respondents for each discussion.

2.2.1. Survey design

Kumroj Buffer Zone Community Forest User Group (BZCFUG) is comprised of residents from nine different villages: Harnari, Bairiya, Gawai, Dharampur, Kumroj, Janakpur, Sisahani, Kapiya, and Ghokrela. Out of 2109 households in the Kumroj BZCFUG, 150 households, representing seven percent sample from each village and the whole, were estimated for the household survey. This total sample number was estimated after randomly conducting 25 household surveys that helped us to estimate the required samples to reflect respondent responses with a 5% margin of error within an 80% confidence interval. With increasing confidence interval, the survey cost, time, and effort would increase, therefore the authors assumed that the sample size is enough to represent the variability around the true response rate at 80% of the time. Further, the response was supported by FGD and KII responses.

We used a stratified random sampling approach, and the household’s responses were stratified into three strata based upon the time taken to reach the forest by foot: near-distance households (0–15 minutes away from the forest), medium-distance households (16–30 minutes away from the forest), and far distance households (>31 minutes away from the forest). This spatial stratum was used because household reliance on forest resources decreases with increasing distance to the forest (Sapkota & Odén, 2008). A total of 61, 49, and 40 households were surveyed from near, medium, and far distances, respectively. Only one hundred and forty-four households were considered for the analysis, as six respondents were unaware of the species. Among six respondents, two were medium-distance respondents and four were far-distance respondents.

2.2.2. Survey types

2.2.2.1. Household survey

The household survey was designed to collect information on the socio-demographic structure of respondents, identify and explore people’s perceptions toward the invasion of M. micrantha, its impacts on their livelihood, and the coping mechanism adopted by the local people (Supplementary material, S1). The survey questions were composed of people’s perception of M. micrantha, their knowledge about M. micrantha, application, collection time, abundance over the last five years, and impact on wildlife availability. Besides, questions on the perceived effects of the change in forest resource availability i.e. fuelwood, fodder, wild edible vegetables; scenario comparison of the current situation with five year ago in collecting forest resources; and changes in their household activities due to invasion were gathered. The survey questions were also related to coping mechanisms focused on managing M. micrantha invasion in farming, ideas to control its invasion, concrete attempts to cope with its invasion, and intervention efforts conducted or support provided by authorized bodies or agencies.

2.2.2.2. Focus Group Discussions (FGDs)

Focus group discussion (FGD) involves a structured meeting with a group of individuals to discuss about specific topic or issue (Hayward et al., 2004). FGDs were done mainly to identify M. micrantha occurrence, its impact on the livelihoods and environment, and to understand the community’s approach to coping with the invasion. Altogether four FGDs were conducted, and each FGD lasted for two hours. The average number of participants for FGD was 10 involving local communities, BZCFUG committee members, and buffer zone committee members. The first FGD was conducted before the start of the household survey to obtain baseline information about the research. Participatory mapping of the community forest was conducted during the discussion, and the members were requested to identify the most invaded ecosystem types by M. micrantha. With this information, it became easy to choose the household based on the distance to the most invaded part of the forest. The information provided by respondents during the household survey was cross-checked through FGDs.

2.2.2.3. Key Informant Interviews (KII)

Key informant interview (KII) entails an in-depth interview with individuals having specific knowledge on a specific topic (Hayward et al., 2004). KIIs were done with CNP officials, local organizations, and buffer zone committee members on the impact of M. micrantha in the study sites.

2.3. Data analysis

Data were analyzed using Chi-square (χ²), logistic regression, correspondence analysis, and paired t-tests. Responses, yes or no toward the M. micrantha invasion, its uses, its impact on livelihood and wildlife, and coping methods were analyzed using a contingency table (Agresti, 2018). These responses i.e. frequencies, were analyzed using Chi-square (χ²) test for their independence with the distance to the forest (near, medium, and far) and socio-demographic structure (Onchiri, 2013). The socio-demographic variables were gender, caste group, education level, income level, occupation, housing type, resident type, landholding size, and family member size (Table 1).

Table 1. Description of variables used in the analysis

Variables	Category used	Description
Caste Group	Damai, Janajati, Tharu, and Brahmin/Chhetri	Damai traditionally engages in crafts like tailoring; Janajati refers to diverse indigenous ethnic groups; Tharu represents an indigenous group in the Terai region; and Brahmin/Chhetri consists of high-caste groups.
Types of Residents	Native and Migrant	Native residents are those originally from the study area, while Migrant residents have relocated from other parts of the country, such as Gorkha, Kaski, Lamjung, Syangja, and Tanahun.
Occupation Types	Agriculture, Jobs, Animal Products, Remittance, and Others	Agriculture involves farming, Job includes formal employment, Animal Product covers animal husbandry, Remittance relies on income from family members working abroad, and Others encompass any other occupation.
Housing Types	General, Mud, Concrete	General housing types have roofing made of corrugated galvalume steel sheet, Mud houses are constructed primarily using mud, and Concrete types are built using concrete for a more durable structure.

Logistic regression was used to understand how socio-demographic variables affect M. micrantha use. The responses (Yes = 1, No = 0) were analyzed using generalized linear function. The response for M. micrantha use was considered as a dependent variable whereas distance to forest and socio-demographic variables were considered as independent variables for logistic regression. The diagnostic analysis suggested that education did not show a significant effect, therefore it was removed from the final model. The model results were interpreted in terms of the odd ratio.

We also modeled the contingency table of ‘yes’ or ‘no’ responses to the multiple questions asked about M. micrantha using the correspondence analysis to determine the relationship with the spatial location. The questions were about the use of M. micrantha, observation in farmland, measures to stop the invasion, its alternative use as bio-products, impact on household activity, change in household structure, and entry into the forest in the current situation and before the invasion. This, correspondence analysis approach analyzes the frequency cross-tables and approximates the chi-square distance in the table with the Euclidean distance on the plot (Kassambara & Mundt, 2020).

We used the paired t-test to evaluate the responses about the change in the number of days from five years ago to now visiting the forest per week and spending hours collecting forest products, such as fuelwood and fodder. The information gathered from FGD and KII was used to validate and support the findings from the household survey, therefore these are presented in the discussion section. All the data analyses were done using the statistical software R 3.6.3 (R Core Team, 2020).

3. Results

3.1. Profile of the respondents

The general socio-economic information of the respondents is presented in Table 2. The majority of the respondents were from the 35–54 years age category, male, literate, and migrant. These respondents settled down close to the forest area within a short walking distance (near = 42.7%) rather than medium (32.6%) and far distance (25%). Houses were primarily concrete-built (56.3%), followed by general-built (house roofing with corrugated galvalume steel sheets) (31.9%), and mud-built (11.8%).

Table 2. Summary of sociodemographic and characteristics of household respondents (n = 144)

Variables	Categories	Mean ± standard deviation	Percentage (%)
Age of respondents (years)		47 ± 12.76 yrs
	<35		26.4%
	35–54		45.8%
	≥55		27.8%
Gender	Male		52%
	Female		48%
Caste group	Damai		3.5%
	Janajati		19.4%
	Tharu		34.7%
	Brahmin/Chhetri		42.4%
Education level	Illiterate		10%
	Primary/Literate		50.7%
	Higher/Secondary		36.2%
	Have a bachelor’s degree		2.8%
Annual household Income level (US dollar)^ϯ		$1693.5 ± 1454.8
	Low ≤ $1000/yr		45.1%
	Average >$1000–$2000/yr		22.2%
	High >$2000		32.6%
Occupation	Agriculture		52.8%
	Job		22.9%
	Animal product ^Ϩ		11.8%
	Remittance		6.3%
	Others		6.3%
Walking distance to the forest area		20.7 ± 12.5 min
	Near (<15 min)		42.4%
	Medium (15 ~ 30 min)		32.6%
	Far (30 ~ 50 min)		25%
Types of residents	Native		51.4%
	Migrant		48.6%
Family members	The number of family members	5.41 ± 2.25 /household
Housing type	Concrete		56.3%
	General		31/9%
	Mud		11.8%
Landholding	Landholding size (ha)	3.59 ± 3.74 ha

^ϯAnnual income in Nepalese rupee/currency (NRP) was converted into US dollars using the ratio of NRP/USD, where 1 USD was equivalent to 110 NRP during the survey year.

^ϨAnimal products include the sales of livestock and fisheries.

Agriculture was found to be a major source of household income contributing 52.8%, followed by jobs (22.9%), and remittance (6.2%) (Table 2). However, the mean annual income from remittance ($3253) was higher than other sources, followed by jobs ($2454), and animal products ($2397). When agriculture was the primary source of income, animal products contributed substantially less; otherwise, the contribution was vice versa (Table 3). Interestingly, the contribution of agriculture ranges from 16.3% to 31.0%, and animal products range from 5.9 to 13.7%, even though the primary source of income was remittance, jobs, or others. Collectively, agricultural and animal products contributed 22.5%, 30%, and 47% to the total income from remittance, jobs, and others, respectively (Table 3).

Table 3. Contributing percentage of primary income sources in the annual gross family income, average income (mean ± standard deviation), and agricultural and animal contribution percentage (mean ± standard deviation) to the primary income sources

Income sources	Total contribution (n = 144)	Average income (mean ± stdev)	^ϯϯAgricultural contribution (%)	^ϨAnimal product contribution (%)
Agriculture	52.78%	$1018 ± 971 (n = 76)	69.7 ± 17.1	32.2 ± 10.7
Animal products	11.81%	$2397 ± 1817 (n = 17)	23.4 ± 23.5	79.5 ± 16.2
Jobs	22.92%	$2454 ± 1593 (n = 33)	16.3 ± 8.12	13.7 ± 11.4
Others	6.25%	$1721 ± 938 (n = 9)	31.0 ± 18.8	15.9 ± 10.2
Remittance	6.25%	$3253 ± 878 (n = 9)	16.6 ± 11.1	5.95 ± 4.38

^ϯϯAgriculture and ^Ϩanimal products contribute to gross family income since it is an integral part of livelihood in the rural community in Nepal.

3.2. Respondents’ perception toward M. micrantha invasion

3.2.1. M. micrantha arrival time and status

Respondents reported different times since they first observed M. micrantha which was found to be after 1993, after the flooding incident in Rapti River, and 3–4 years ago (Table 4). The responses were significantly associated with resident types particularly because migrant respondents predominantly belong to the group that arrived after 1993. A significantly higher proportion of respondents had observed M. micrantha in the farmland which was associated with distance from the forests variable. However, none of the demographic characteristics were significantly associated with observing M. micrantha in the farmland (Table 4).

Table 4. Perception related to M. micrantha invasion

Variables	Category/Respondent (%)	χ2	p-value
Arrival of M. micrantha
General	After 1993 (61.1); 3–4 years ago (28.5); Not sure (10.4)	57.04	<0.001
Resident type	Native (36.8); Migrant (24.3)	12.98	<0.001
Observation in farmland	Yes (68.75), No (31.75)	20.25	<0.001
Walking distance from forest	Near (34.7); Medium (20.8); Far (13.2)	9.76	0.07
Usage of M. micrantha	Using (61.8); Not using (38.2)	7.5	0.005
M. micrantha abundance and invasion	Increasing (44); decreasing (41); same (10); cannot say (5)	70.5	<0.001
M. micrantha as a bio-product	Using as a raw material (18); not using (82)	58.78	<0.001
Perception of M. micrantha invasion
General	Negative (43.7); mixed (29.2); no feeling (27.1)	7.13	0.028
Walking distance from forest	Near (29.8); medium (10.4); far (3.4)	40.41	<0.0001
Resident type	Migrant (27.8); native (16)	7.13	0.028

3.2.2. Application of M. micrantha

The majority of the households were found to use M. micrantha primarily as fodder for goats (32.6%) and cows (0.7%), manure or compost (3.5%), and making rope (0.69%) (Table 4). It was mostly collected during March-May (72.7%), followed by Jun-Aug (12.7%), Nov-Feb (9.1%), and throughout the year (5.5%). Interestingly, the use of M. micrantha as fodder for goats was similar among the people in different distance categories. The negative estimate representing the caste indicated the decreasing probability of M. micrantha use with other castes (Janjati and Damai), but not different with Brahmin/Chhetri when compared to the Tharu. Tharu community primarily uses the M. micrantha (43.6%), followed by Brahmin/Chhetri (38.2%), Janjati (14.5%), and Damai (3.7%). The result of logistic model suggested the significantly decreasing probability of M. micrantha use with the interaction of landholding and household members and interaction of residents and house build type (Table 5).

Table 5. Parameter estimates for the generalized model with logit function for the response on the use of Mikania micrantha (Yes = 1, No = 0) at a significance level (α) of 0.05. Odds ratio is obtained by exponentiation of the estimate of the model

Variables	Estimates	Std. error	z-value	Pr(>|Z|)	Odds ratio
Intercept	−4.696	1.596	−2.943	0.003*	0.009
Income source_Agriculture	1.801	1.230	1.464	0.143	6.058
Income source_ Animal products^Ϩ	1.766	1.337	1.323	0.186	5.864
Income source_Job	2.357	1.253	1.881	0.06	10.556
Income source_Remittance	0.556	1.545	0.360	0.719	1.744
Landholdings	0.432	0.201	2.148	0.032*	1.541
No of family members	0.694	0.185	3.744	<0.001*	2.001
Residents_Native	0.045	0.645	0.071	0.944	1.047
Housing Type _General	−1.694	0.741	−2.285	0.022*	0.184
Housing Type_Mud	2.682	1.525	1.758	0.079	14.618
Distance_Far	−0.504	0.561	−0.898	0.369	0.604
Distance_Medium	0.329	0.520	0.633	0.527	1.389
Caste_Brahmin/Chhetri	−1.0434	0.6008	−1.736	0.083	0.352
Caste_Damai	−0.4900	1.1600	−0.422	0.673	0.613
Caste_Janjati^ϨϨ	−1.6386	0.6890	−2.378	0.017*	0.194
Landholdings: No. of family members	−0.0747	0.0308	−2.425	0.015*	0.928
Native: Housing Type _General	0.3698	0.9631	0.384	0.701	1.447
Native: Housing Type _MUD	−6.8287	2.1890	−3.120	0.002*	0.001

^ϨAnimal products = Sales of livestock, dairy product, and fisheries; ^ϨϨJanjati = Gurung, Magar, and Newars; *significance level of α = 0.05; The parameter estimate significance is compared with the base level for each factor. For example, the base level are others, near, and Tharu for the income source, distance category, and caste group respectively.

3.2.3. M. micrantha abundance and invasion

The responses on the abundance of weed were found to be increasing, decreasing, same, and cannot say. Respondents reported they had seen it everywhere (54%) in high amounts (42.8%) in the farmland (1.5%) and destroying the forest (1.5%), suggesting an increasing trend (Table 4). However, households reporting a decreasing trend have observed less M. micrantha in recent years (82.1%) and didn’t notice it in the farmland (17.9%).

The potential factors for increasing M. micrantha abundance were due to forest closure (31.7%), seed dispersal due to wind (23.8%), and other factors like lack of management, human activity, and dispersal by wild animals. In contrast, respondents perceived decreasing abundance because of natural processes (35.9%), timely mechanical intervention (15.4%), and implementation of silvicultural operation (10.2%) in the forest, limiting the abundance of this invasive species. A few respondents (10.26%) believed that it was decreasing, but they had no idea how it decreased. Also, some respondents (10%) believed that climate change might be affecting the abundance of M. micrantha (Figure 1).

3.2.4. M. micrantha as a bio-product option

A significantly low proportion of respondents (18%) reported using as a bio product (Table 4). Among them, 32% reported using it as a bio-briquette or charcoal and 68% as a manure. It was noticed that households living close to the forest with a mean annual income of less than $1000 used M. micrantha as a bio-briquette or charcoal. It was also used as manure by the respondents living near the forest than a distant household, regardless of different income levels.

3.2.5. People’s perception on M. micrantha invasion

Respondents showed significantly different views towards M. micrantha invasion: negative (43.7%), mixed (29.2%), and no feeling (27.1%). The negative feelings decreased with increasing distance, conversely, with increasing distance from the forest, ‘no feeling’ responses increased (Table 4). People’s perception of M. micrantha’s invasion was also significantly associated with the resident types. The migrant residents had the most negative feelings, the native residents had indifferent feelings responses to negative, mixed, and no feelings respectively. However, the perception was not significantly associated with gender, caste group, education, income, occupation, housing type, and landholding size (Table 4).

3.2.6. Spatial perception on M. micrantha

The correspondence analysis with the spatial location suggested that 73% of the local people’s positive perception (Yes- response) significantly varied with the increasing distance along the first axis (Figure 2). The first axis showed that most of the positive perceptions such as the use of M. micrantha, observing in the farmland, the idea to stop the invasion, and using it as a bio-product, are closely correlated with distance from the forest. Results suggested that people living at medium and far distances have perceived the change in their household structure and access to the forest. The second axis explained 27% of the variability among the perception types. The variability in the perception decreased with the questions asked about the invasive species related to mundane chores among the respondents living near and medium distances rather than far distances. However, when the question is not closely related to the people, the variability increases in the perception. For example, the perception of the change in wildlife is associated with the far distance (Figure 2).

Figure 3. Chisquare model correspondence analysis showing variability in the peoples’ spatial perception (solid triangles) of Mikania micrantha in the study area, Kumroj Buffer Zone Community Forest, Chitwan, Nepal. The first dimension (left to right) shows the variability due to the distance. The second dimension (top to bottom) shows variability among the perception type.

Figure 4. Inhibition by M. micrantha on native vegetation community forest area, Kumroj BZCF, CNP, Nepal. In the picture Aspidopterys cordata (a native vegetation with some traditional medicinal values) is covered by the weed.

Figure 2. Response percentage on the potential factors regulating the abundance (increase & decrease) of Mikania micrantha and its invasion.

3.3. Impact of M. micrantha

3.3.1. Impact on the habitat of wildlife

The respondents’ belief on the impact of M. micrantha on wildlife habitat was not significantly different than no impact (Table 6). Respondents perceived their impact on wildlife because it 1) caused habitat destruction (Figure 4) or shifted vegetation composition (43%); 2) impacted grazing for herbivores (31.7%); 3) increased the incidence of wildlife encounters in a village (28%); and 4) reduced the number of wildlife observations (6%). In contrast, people who believed M. micrantha had no impact on wildlife perceived that it created a hiding cover for wildlife (61.3%); provided additional food to the wild animals as they often browse on the weed (4.8%); did not affect at all (17.8%); and 4) do not know about the impact (16.1%). People believed that the habitat of other animals, such as one-horned Rhino, Elephant (Elephas maximus), Wild boar (Sus scrofa), and Chital (Axis axis) were affected mainly by the invasion.

Table 6. Impact of M. micrantha

Variables	Category/Respondent (%)	χ2	p-value
General	Negative (43.7); mixed (29.2); nothing (27.1)	7.13	<0.02837
Walking distance from forest	Near (29.8); medium (10.4); far (3.4)	40.41	<0.0001
Resident type	Migrant (27.8); native (16)	7.13	<0.02837
Impact of M. micrantha on different areas
Impact on the habitat of wildlife	Impact (57); no impact (43)	2.51	0.1133
Impact on access to forest resources	Collect multiple products (80.5); Don’t collect (19.5)	52.56	<0.0001
Forest product use from CF vs BZF	Fuelwood (87.3)	59.64	<0.0001
	Fodder (90.3)	65.28	<0.0001
Quality and quantity of timber	Decrease in timber quality (83.6)	48.44	<0.0001
	Decrease in timber quantity (63.6)	65.14	<0.0001
Quality and quantity of fodder	Decrease in fodder quality (81.5)	39.76	<0.0001
	Decrease in fodder quantity (75.7)	91.01	<0.0001
Quality and quantity of wild vegetables	Decrease in quality and quantity of wild vegetables (80.5)	14.05	<0.0001
Impact on the household activity	Agree (68); disagree (32)	18.06	<0.0001
Alternative to scare forest resources	Reduce forest consumption (19.5); practice agroforestry (16); travel to more forest area (12.5); adopt other measures (52)	57.72	<0.0001
Change in household structure	Disagree (79)	47.84	<0.0001
Potential controlling and coping measures for M. micrantha invasion
Control measures	Mechanical (86.6); chemical treatment (11.1); doing nothing (2.1)	187	<0.0001
Control measures with distance	Distance	11.63	<0.0203
	Caste group	14.07	<0.0288
Coping measures	Utilizing as fodder (34); compost manure (30.5); bio-briquette (2.8)	28.3	<0.0284
Coping measures	Housing types	13.69	<0.033
Institution responsibility	BZCFUG (30); National Trust for Nature Conservation (11); Buffer zone management committee (9%)	63.17	<0.0001

3.3.2. Impact on access to forest resources

Significantly, a large proportion of the respondents (80.5%) visited the forest to collect multiple forest resources to sustain their livelihood either from community forests or buffer zone forests. A high proportion of respondents significantly visited community forests for collecting fuelwood (87.3%) and fodder (90.3%) than buffer zone forest (Table 6). Respondents also collected wild edible vegetables, such as Matteuccia struthiopteris (Nuiro), Asparagus officinalis (Kurilo), from community forests (92.7%, n = 41) than buffer zone forests (7.3%). However, very few respondents (n = 8) reported collecting non-timber forest products from both community forestry (50%) and buffer zone forest (50%). Because of the invasion of M. micrantha, the respondents reported a significant decrease in the quality and quantity of the forest resources available to them (Table 6).

The pairwise t-test suggested that the response on the current average time to collect forest products, 2.47 ± 0.74 hours (mean ± stdev.), was significantly higher (t = 21.45, df = 114, p-value <0.0001) than five years ago average time, 1.2 ± 0.45 hours. The t-test results suggested the current mean collection of forest product bundle (1.5 ± 1.08 bundle) didn’t differ significantly from the five years ago (1.7 ± 1.10 bundle). However, the current average number of visits to the forest per week, 2.20 ± 1.01 trips, was significantly lower (t = 16.20, df = 196.56, p-value = <0.0001) than the five-year scenario, i.e. 5.25 ± 1.70 trips.

3.3.3. Impact on the household activity

Respondents reported a significant effect on their household activity due the invasion (Table 6). Decrease in farm productivity (34%), problems while accessing forest products (31.9%), and decrease in availability of fuelwood (21.5%) and fodder (3.5%) in the forest (Figure 4). As a coping, respondents reduced forest product consumption and adopt other measures (Table 6). While 21% of the respondents (n = 30) believed that the invasion has decreased the availability of hay as fodder (66.7%) and cover material for housing (33.3%). Most of these affected respondents had a mean annual income of $1000; however, the distance from the forest area was not a contributing factor.

3.4. Potential controlling and coping measures for M. micrantha invasion

Respondents reported using predominantly mechanical methods to control M. micrantha in their farmland (Table 6). The mechanical method includes cutting and uprooting, and it is often followed by burning. The mechanical methods were used by the respondents living near the forest area (38.9%) more than the respondents living at medium (24.3%) and far distances (23.61%). Similarly, this method was primarily used by Brahmin/Chhetri (39.6%), followed by Tharu (25.7%) and Janajati (18.7%). However, responses to the choice of control methods did not differ due to other demographic factors.

As housing type changed from concrete to general to mud type respectively, a decreasing trend of using M. micrantha as compost manure (18.7%, 5.3%, and 3.5%), fodder (22.2%, 6.2%, and 5.5%), and doing nothing (13.9%, 16.7%, and 2.1%) was observed. However, coping measures were not significantly associated with other demographic factors. Interestingly, respondents reported using M. micrantha as fodder (19%, n = 27), compost manure (16%, n = 23), and bio-briquette (1.4%, n = 2) were primary literate.

69% of the respondent, suggested some intervention methods to help stop M. micrantha invasions, such as silvicultural operations (34.7%), mechanical treatment (31.2%), research (2.1%), and training to make bio-briquette or charcoal from M. micrantha (0.7%).31.2% of the respondent had no suggestion for intervention action to stop the M. micrantha invasion.

Respondent reported that the community forest user group had primarily implemented them, though other agencies had shown some intervention actions (Figure 5). Respondents suggested that CNP (50%) should initiate the intervention action, followed by the BZCFUG (30%), National Trust for Nature Conservation (11%), and Buffer zone management committee (9%) (χ2 = 63.17, df = 3, p-value <0.0001). Respondents from FGD also iterated the role of CNP and urged to take leadership in invasive plant management in the area.

Figure 5. M. micrantha invading wheat field, Ghokrela village, Kumroj BZCFUG.

Figure 6. Response percentage for the intervention actions implemented by the concerned agencies to control the invasion of Mikania micrantha. BZCFUG= Buffer zone community forestry user group; NGO = non-governmental organization.

4. Discussion

The M. micrantha invasion is reported to be present in Nepal since 1993 and it is spreading rapidly in the forests, grasslands, and wetlands including the study site: Chitwan National Park (Rai & Rai, 2013). Local communities believed that vines of M. micrantha might be transported to the area by river flooding which is also reported by other scholars (Rai & Scarborough, 2015; Tiwari et al., 2005) Moreover, these observations find resonance among key informants such as the head of the buffer zone committee, officials from CNP, and the secretary of the Kumroj buffer zone community forest. Moreover, these findings also align with the insights obtained from in-depth group discussions, highlighting a common thread in the gathered knowledge. The arrival time, however, differed with the type of residents, for example, the native population believed that M. Micrantha had started an invasion after 1993, impacting the biodiversity and livelihood, whereas migrants perceived the recent invasion after the 2002 Rapti river flooding (Rai & Rai, 2013).

Local people’s livelihood, which depends on agriculture and natural resources, have been severely affected due to the invasion (Khadka, 2017). Our study suggested that rural communities have direct but different levels of dependency on natural resources that vary with primary sources of income, such as agriculture, animal products, employment, and remittance. The rural community favored native species for firewood and fodder, but M. micrantha invasion affected the supply from the buffer zones (Rai et al., 2012b; Sapkota, 2007). The infestation of M. micrantha has influenced the supply of forest products to the local community in two ways. Firstly, the abundance of M. micrantha reduces the growth and availability of native species. The park official reported that the invasive species overshadowed small trees, shrubs, and herbs, resulting reduction of native species (Orwa et al., 2009; Sapkota, 2007). Secondly, M. micrantha itself does not offer any of the forest products required for rural communities. Household survey data, FGD, and KII revealed that forest composition has changed over the years, which, however, requires a detailed forest inventory to validate the respondents’ perceptions. Furthermore, these findings are consistent with the results presented by Ram (2008). The availability of essential forest products such as fuelwood and fodder has decreased, forcing households to spend more time collecting forest products as a consequence of the invasion of M. micrantha and the potential forest closure policy of BZCFUG (Adhikari et al., 2004). Adhikari et al. (2004) also found that the number of households entering the forest regularly to collect forest products has decreased. For those who were collecting forest products from their forest, the time required to collect the forest products for a daily requirement increased by double. Also, the frequency of entering the forest to collect forest products decreased substantially over the years. Similarly, the forest products collected per trip have also decreased. The number of households experiencing changes in household activities compared to five years ago indicated that colonization of M. micrantha could be one of the reason. For example, local people started using alternative cooking methods like improved cooking stoves which require less firewood.

Local people perceived an increase in the risk of M. micrantha extension to the farmland (Figure Figure 4) due to the close vicinity of agricultural lands to the forested areas provided that M. micrantha can find its way into farmers’ fields which can increase weeding cost year after year (Tiwari, 2005). The species has significantly decreased farm productivity and contributed to scarce forest product availability (Rai et al., 2012a). Furthermore, M. micrantha may be one of the numerous invasive weeds that farmers must battle (Baral & Adhikari, 2017).

When a exotic invasive species enters an ecosystem, it affects the ecosystem’s structure and functioning, as well as the delivery of ecosystem services (Rai & Scarborough, 2012). M. micrantha also invades the forest to the point that it suffocates the ground flora, preventing seedlings of other species from blooming and reducing the forest’s species variety (Baral & Adhikari, 2017). Chitwan National Park contains a diverse flora and wildlife, and it is one of the best refuges for the Bengal tiger (Panthera tigris), as well as one of the last populations of the great one-horned rhino in Nepal (Mishra & Jefferies, 1991). Studies reported a significant invasion of M. micrantha in the park’s northern core and buffer zone (Sapkota, 2007), affecting the availability of food for one-horned Rhino (Murphy et al., 2013). Reduced grazing habitat is expected to have a significant influence on the total herbivore population in Chitwan National Park and its buffer zone forest. Our study also indicates that M. micrantha had affected wildlife habitat by invading grazing areas through habitat destruction or vegetation composition shift and limiting the frequency of wildlife observation. This change in the natural ecosystem of the park has not only affected the availability of the resources being extracted from the park, but it has also influenced the tourism business (Baral & Adhikari, 2017) which is one of the sources of income for the local people of buffer zone area of the Chitwan National Park in Nepal.

The impact of invasion varies with the households, depending on the distance from the forest, the type of residents, and other household characteristics. Considering findings on the introduction of M. micrantha’s arrival time, it could be inferred that the impact of species is well directed to most of the local residents, old age groups, specific caste groups, households with better houses, and people living near forest resources. Studies showed that people living near the forest are more affected by the invasion but better understand M. micrantha than distant users (Khadka, 2017). The household residing close to the forest collect more forest products and therefore are more likely to be affected by the invasion than the distant users (Rai & Scarborough, 2015).

Communities are responding and adapting to the increasing invasion using their local knowledge and practices in the study site (Ojija et al., 2019). Research showed that there are no recognized effective control techniques for this invasive species and suggested an effective approach to control M. micrantha invasion by avoiding spreading in the first place (Ojija et al., 2021; Zhang et al., 2004). Local people mostly used the uprooting method to control the invasion, which is also common in other areas due to its cost-effectiveness, environment friendly, and require low knowledge than the chemical method (Rai & Scarborough, 2012; Zhang et al., 2004). However, it could be an expensive method in the developed countries. A study conducted in the grasslands of CNP about the efficiency of treatments used to reduce M. micrantha invasion reported controlled fire being a more effective method than manual cutting (Aryal et al., 2018). Few respondents also used it as fodder during the dry season, but M. micrantha reportedly causes stomach problems in livestock (Siwakoti, 2007). It indicates that communities use M. micrantha during extreme emergency conditions of fodder scarcity (Khadka, 2017).

Some respondents started to transform M. micrantha into beneficial products like bio briquette, charcoal, and compost manure. Local people can make a good income if these products receive good market value (Shrestha, 2019b); however, these efforts are currently at a low scale, and communities do not have adequate technical knowledge and finance to sustain the business. Respondents primarily seek help from government agencies to adopt intervention actions and strategies to reduce the M. micrantha invasion in their forests and farmlands. Training and capacity-developing activities would enhance the skill of the local people to effectively manage the invasive species, which can be included while designing plans and programs to control invasive species.

5. Conclusions

The study explores how people perceive the invasion of M. micrantha, which rapidly spread after 1993, suppressing native vegetation. This invasion led to decreased forest product quantity and loss of preferred species, compelling locals to travel further for resources. Proximity to forests influenced perception: those closer witnessed ecological damage and economic losses, while those farther away found M. micrantha visually appealing. People’s knowledge, abundance perception, and responses varied with distance, but not utilization patterns. Some used it as fodder, while others explored bio-products like briquettes. Considering the detrimental effect of M. micrantha on the livelihood and environment, the study recommends taking immediate action to control the invasion. Additionally, given the fact that the people are gradually getting used to it, the management interventions may likely receive local people’s support to effectively manage the M. micrantha and reduce its invasion.

Acknowledgements

The authors are thankful to the Institute of Forestry, Tribhuvan University, Mississippi State University, and University of Arkansas System Division of Agriculture, and the Arkansas Forest Resource Center, University of Arkansas at Monticello for supporting this research work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data not available-participant consent.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/27658511.2024.2362500

Additional information

Funding

The study was supported under “Student Research Grant #GI17 from Hariyo Ban Program, WWF Nepal.