ISSN: 0215-6334 | e-ISSN: 1907-770X The Southeast Asian Journal of Tropical Biology Vol.
32 No.
2, 2025: 151 - 161
DOI: 10.
11598/btb.
Research Paper
INVASIVE ALIEN PLANT SPECIES IN THE RIPARIAN
AREAS OF NORTHERN SAMAR.
PHILIPPINES
Joey Liza L.
Abobo*.
Joy A.
Esmabe.
Marjurie L.
Baldoza.
Princess L.
Cerbito.
John Mark P.
Garbo.
Ramon Philip L.
Bacayo.
Chitlyn C.
Tenedero.
Maricar D.
Lameda.
Rica Joy B.
Saavedra.
Cresil S.
Turbanada, and Roanne B.
Romeroso Department of Biology.
College of Science.
University of Eastern Philippines.
Catarman.
Northern Samar 6400.
Philippines ARTICLE HIGLIGHTS
ABSTRACT
A A pioneering study of invasive alien plant species in the riparian areas of Northern Samar A Species composition, endemism, and conservation status of introduced A Out of 65 introduced species, 32 were listed as invasive Riparian areas are highly dynamic and naturally disturbed, making them particularly susceptible to invasion.
Invasive Alien Plant Species (IAPS) are widely distributed in these areas due to the favorable environmental conditions that support their growth and persistence.
This study is a pioneering effort to document the invasive alien plant species thriving in the riparian zones of Allen.
Biri.
Catarman.
Gamay.
Mapanas.
Laoang.
Lapinig.
Las Navas, and Pambujan in Northern Samar.
Sampling was conducted from March to December Six transect lines, each measuring two kilometers per site, were established in the riparian areas to identify existing invasive alien In total, 60 transect lines were set up across all sampling areas.
As a result, 65 introduced plant species belonging to 24 families and 56 genera were documented in the riparian areas of Northern Samar.
The families with the highest number of species were Poaceae .
Asteraceae .
Cyperaceae.
Fabaceae, and Lamiaceae .
The remaining families had fewer than five species each.
The most common invasive plant species recorded was Psidium guajava L.
, which was present in all sampling areas.
Based on life forms, the study identified two tree species, 17 shrubs, three vines, one epiphyte, and 42 herbs.
Conservation status was determined using the latest IUCN and DENR listings .
7Ae.
One taxon was classified as Data Deficient, 32 as Least Concerned, and the remaining species as Not Evaluated.
In contrast, no taxa were assessed in the DENR 2017Ae11 listing.
Furthermore, of the 65 introduced plant species documented, 10 were recorded as invasive in the Global Invasive Species Database, while 22 were listed in the Global Register of Introduced and Invasive Species Database.
Although invasive alien species have long been recognized as posing serious threats to human health, forestry, agriculture, fisheries, and natural biodiversity, no comprehensive assessment of their status, trends, causes, impacts, management, and governance issues has been conducted worldwide.
Thus, this study aimed to supplement existing data on invasive plants and assist policymakers in developing policy frameworks for managing invasive alien plant species to mitigate their impacts on human health and the environment.
Article Information Received : 29 September 2024 Revised : 8 April 2025 Accepted : 29 April 2025 *Corresponding author, e-mail:
joeyaceaeliz@gmail.
Keywords: invasive alien plants.
Northern Samar, riparian areas, biodiversity assessment BIOTROPIA Vol.
32 No.
2, 2025
INTRODUCTION
Invasive alien species (IAS) are non-native organisms that pose risks to both human health and the environment.
They are regarded as the second most significant threat to biodiversity after habitat loss (Bellard et al.
Whether introduced intentionally or unintentionally, the introduction, dispersal, and utilization of alien species have had profound impacts on ecosystems and economies.
Because many invasive alien species are highly adaptable, capable of rapid growth and reproduction, the environmental damage they cause is often irreversible and can lead to the extinction of endemic species.
Furthermore, biological invasions have severe socio-economic and public health impacts (Shackleton et al.
According to Castro-Dyez et al.
the perceived socio-economic benefits of certain potentially invasive plant species in urban and rural areas have contributed to the rapid spread of some IAS in forest ecosystems.
Numerous studies have been conducted worldwide to examine the effects of invasive alien species on human health, ecosystem services, biodiversity, and economic activities (Katsanevakis et al.
However, research on the impacts of IAS in the Philippines remains scarce.
Owing to its archipelagic nature, which promotes geographic isolation and endemism (PTFCFI 2.
, the Philippines is recognized as one of the worldAos 17 mega-diverse countries (Keong 2.
Yet, island ecosystems are particularly vulnerable to invasive alien species, which can cause population declines and extinctions, especially among endemic taxa.
Samar Island Natural Park (SINP), located on the countryAos third-largest island, is a designated forest reserve with exceptionally rich biodiversity.
Recent ecological assessments have documented 212 tree species, 182 terrestrial vertebrates, 24 amphibian species (Diesmos et al.
Diesmos et al.
, and 31 snake species (Leviton et Weinell et al.
Additional floral (Quimio 2.
and faunal (Patindol 2.
surveys have been conducted in five SINP watersheds.
Floristic inventories of alien species are essential for developing conservation programs and policies aimed at addressing forest conservation challenges.
Effective management is better achieved through comprehensive strategies that map relationships between invasive species and at-risk native species rather than focusing solely on individual taxa.
Globally, invasive species are among the leading drivers of ecosystem-wide biodiversity loss and species extinctions.
The purpose of this study is to identify invasive alien plant species (IAPS) in the riparian areas of Allen.
Biri.
Catarman.
Gamay.
Mapanas.
Laoang.
Las Navas.
Lapinig.
Lavezares, and Pambujan in Northern Samar.
Philippines, focusing on species composition, endemism, and conservation status.
Conducting research on invasive plant species is crucial, as it helps shed light on the ecological consequences of non-native plant invasions.
The findings will raise public awareness and promote recognition of the harmful effects of such species.
Moreover, the study encourages the development of new approaches to mitigation and restoration, including management interventions and the evaluation of IAPS impacts.
This research was conducted in the aforementioned riparian areas because no prior studies have examined invasive plant species in these habitats, even though riparian zones often harbor numerous invasive species that can outcompete or displace native vegetation.
MATERIALS AND METHODS
Study Area This study was conducted in 10 riparian areas, .
Allen.
Biri.
Catarman.
Gamay.
Laoang.
Mapanas.
Lapinig.
Las Navas.
Lavezares, and Pambujan, located in Northern Samar.
Visayas Island.
Philippines (Table 1.
Fig.
Invasive alien plant species in the riparian areas of Northern Samar.
Philippines - Abobo et al.
Table 1 Riparian areas in Northern Samar as the sampling sites Riparian areas Coordinates Allen 12A30Ao04Ay N 124A17Ao14Ay E Biri 12A39Ao40Ay N 124A24Ao31Ay E Catarman 12A25Ao08Ay N 124A38Ao30Ay E Gamay 12A23Ao05Ay N 125A16Ao52Ay E Laoang 12A37Ao19Ay N 125A01Ao05Ay E Mapanas 12A28Ao08Ay N 125A14Ao12Ay E Lapinig 12A18Ao52Ay N 125A17Ao27Ay E Las Navas 12A18Ao24Ay N 125A00Ao59Ay E Lavezares 12A31Ao27Ay N 124A23Ao09Ay E Pambujan 12A27Ao50Ay N 124A56Ao24Ay E Figure 1 Riparian areas as sampling sites in the Samar Island Natural Park Notes: A.
Map of the Philippines showing Samar Island Natural Park.
Samar Island Natural Park Map showing the sampling areas.
Data Analysis Plant Collection and Identification This study was conducted in March-December 2023 in the ten .
riparian areas of Northern Samar, namely Allen.
Biri.
Catarman.
Gamay.
Mapanas.
Laoang.
Las Navas.
Lapinig.
Lavezares, and Pambujan.
Six transect lines, measuring two kilometers per site, were laid randomly in the riparian areas to identify the existing invasive alien Overall, a total of 60 transect lines were established for all sampling areas.
All documented invasive plant species were completed with proper photo documentation for identification and verification.
Other data collected during the survey included live photographs and growth habits .
, trees, shrubs, herbs, vines.
Plant Identification and Conservation Status All samples were identified using species descriptions, taxonomic keys, comparison of type specimens, and available web resources.
The CoAos Digital Flora (Pelser et al.
2011 onward.
Plants of the World Online (POWO 2.
Global Register of Introduced and Invasive Species-Philippines, and Global and Invasive Species Database were also used as identification aids.
Additionally, the conservation of each speciesAo status was determined using the International Union for Conservation BIOTROPIA Vol.
32 No.
2, 2025
of Nature (IUCN) Red List (IUCN Standards & Petitions Committee 2.
and the Department of Environment and Natural Resources Administrative Order 2022-11 (DENR-DAO DENR 2.
RESULTS AND DISCUSSION
Inventory Sixty-five introduced plant species were recorded in the riparian areas of Northern Samar, representing 24 families and 56 genera.
All 65 species identified at the species level are considered non-endemic to the Philippines.
The species occurring in Northern SamarAos riparian areas are presented in Table 2.
The Poaceae family was the most wellrepresented, with 13 species, followed by Asteraceae with 12 species, and Cyperaceae.
Fabaceae, and Lamiaceae with 5 species each.
Other plant families had fewer than five species.
The most commonly documented life forms among these invasive plant species were herbs .
, followed by shrubs .
, vines three, trees two, and one epiphyte.
Some of these invasive species were extremely rare in certain locations, while others were more common in different areas.
This variation is likely due to differing environmental conditions.
Differences in soil nutrient availability, pH, type, and water retention capacity across sites may influence the ability of certain invasive species to thrive in some areas while remaining scarce in others.
Additionally, environmental factors such as temperature and humidity may affect the distribution, abundance, and growth of invasive plant species, contributing further to their spatial variation.
It is noteworthy that the plant families documented in this study, such as Asteraceae.
Cyperaceae.
Fabaceae.
Lamiaceae, and Poaceae, are also commonly found in riparian areas in other countries, such as China and India.
Furthermore, the IUCN Classification and the DENR-DAO 2017Ae11 are used to devise the conservation status of the species in riparian areas.
As a result, according to the IUCNAos most recent listing, one taxon is categorized as Data Deficient, 32 as Least Concerned, and the remaining taxa are Not Evaluated.
In contrast, no taxon was not evaluated in DAO 2017Ae11.
The life forms and taxonomic distributions of plant species were recorded in each sampling area (Table .
In Allen, 9 species were identified, consisting of 1 tree, 1 shrub, and 7 herbs, with most belonging to the Asteraceae family.
Biri had 10 species, including 2 tree species, 3 shrubs, 3 herbs, and 2 vines, representing mainly the Asteraceae and Fabaceae families.
Catarman comprised 18 species, including 2 trees, 4 shrubs, and 12 herbs, with most species from the Asteraceae and Poaceae Gamay was dominated by 11 species:
2 trees, 2 shrubs, 6 herbs, and 1 vine, primarily from the Asteraceae family.
Lavezares had 10 species, including 1 shrub, 8 herbs, and 1 epiphyte, with most species belonging to the Asteraceae Laoang had the highest diversity, with 23 species including 1 tree, 3 shrubs, and 19 herbs, predominantly from the Asteraceae.
Cyperaceae, and Poaceae families.
Las Navas had 15 species: 2 trees, 2 shrubs, 10 herbs, and 1 vine, mostly from the Fabaceae and Asteraceae families.
Lapinig had 17 species, comprising 1 tree, 2 shrubs, 13 herbs, and 1 vine, primarily from the Asteraceae and Fabaceae families.
Mapanas had 14 species, including 2 trees, 1 shrub, 10 herbs, and 1 vine, mostly from the Asteraceae and Poaceae families.
Finally.
Pambujan recorded 17 species: 1 tree, 4 shrubs, 11 herbs, and 1 vine, with most species belonging to the Asteraceae family.
Laoang recorded the highest number of introduced plant species in this study, with 23 species documented.
more than any of the other nine sampling areas.
The riparian zones of Lapinig.
Pambujan, and Las Navas are subject to disturbance due to transportation activities.
Additionally, the riparian areas of Lapinig serve as access routes for local communities collecting bivalves, univalves, and crabs.
According to Mukaromah .
, the distribution of invasive plant species is closely associated with the level of disturbance in their respective habitats.
The study also concluded that invasive species tend to be superior competitors, more tolerant of human disturbance, and capable of reducing both the abundance and diversity of native species.
Therefore, the disturbances observed in the riparian areas of Northern Samar likely contribute to the widespread distribution of invasive alien plant species along the riverbanks.
Invasive alien plant species in the riparian areas of Northern Samar.
Philippines - Abobo et al.
Table 2 Endemism and conservation status of introduced plant species in the riparian areas of Northern Samar
Family Acanthaceae Amaranthaceae Apiaceae Asteraceae Species Endemism
Conservation status
IUCN
DENR
Acanthus ilicifolius L.
Odontonema cuspidatum (Nee.
Kuntze Amaranthus spinosus L.
Amaranthus viridis L.
Cyathula prostrata (L.
) Blume Centella asiatica (L.
) Urb.
Ageratum conyzoides L.
Ageratum houstonianum Mill.
Chromolaena odorata (L.
) R.
King & Rob Cyanthillium cinereum (L.
) H.
Rob.
Eclipta prostrata (L.
) L.
Elephantopus mollis Kunth Elephantopus tomentosus L.
Helianthus annuus L.
Mikania cordata (Burm.
) B.
H Rob.
Mikania micrantha Kunth Pseudelephantopus spicatus (Juss.
ex Aubl.
Rohr Sphagneticola trilobata L.
Boraginaceae Heliotropium indicum L.
Commelinaceae Commelina diffusa Burm.
Convolvulaceae Ipomoea aquatica Forssk.
Actinoscirpus grossus (L.
) Goetgh.
Simpson Cyperus brevifolius (Rottb.
) Endl.
ex Hassk.
Cyperus iria L.
Cyperus rotundus L.
Scleria scrobiculata Nees & Meyen Caesalpinia pulcherrima (L.
) Sw.
Leucaena leucocephala (Lam.
) de Wit Mimosa pudica L.
Pueraria montana (Lour.
) Merr.
Senna occidentalis (L.
Dicranopteris linearis (Burm.
) Underw.
Hyptis brevipes Poit.
Abelmoschus moschatus Medik Sida acuta Burm f.
Sida rhombifolia L.
Urena lobata L.
Cyperaceae Fabaceae Gleicheniaceae Lamiaceae Melastomataceae Myrtaceae Nephrolepidaceae Melastoma malabathricum L.
Psidium guajava L.
Nephrolepis cordifolia (L.
) C.
Presl Onagraceae Ludwigia octovalvis (Jacq.
) P.
Raven Piperaceae Piper aduncum L.
BIOTROPIA Vol.
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Family Species Poaceae Conservation status
Endemism
IUCN
DENR
Agrostis gigantea Roth Arundo donax L.
Bambusa vulgaris Schrad.
ex J.
Wendl Bromus inermis Leyys.
Echinochloa colonum (L.
Eleusine indica (L.
) Gaertn.
Eragrostis elongata (Willd.
) Jacq.
Eragrostis pilosa (L.
) P.
Beauv Imperata cylindrica (L.
) P.
Beauv.
Oplismenus compositus (L.
) P.
Beauv.
Oryzopsis hymenoides Ricker ex Piper Saccharum spontaneum L.
Themeda triandra Forssk.
Polygonaceae Persicaria barbata (L.
) H.
Hara Schizaeaceae Lygodium microphyllum (Cav.
) R.
Scrophulariaceae Scoparia dulcis L Solanaceae Physalis peruviana L.
Tiliaceae Triumfetta rhomboidea Jacq.
Lantana camara L.
Stachytarpheta cayennensis (Rich.
) Vahl Stachytarpheta indica (L.
) Vahl.
Stachytarpheta jamaicensis (L.
) Vahl Hedychium coronarium J.
Koenig Verbenaceae Zingiberaceae Table 3 Species composition and classification of introduced plant species in the riparian areas of Northern Samar Life form Sites Tree Shrub Classification Herb Vines Epiphytes Family Genus Species Allen Biri Catarman Gamay Lavezares Laoang Las Navas Lapinig Mapanas Pambujan Invasive alien plant species in the riparian areas of Northern Samar.
Philippines - Abobo et al.
Distribution Invasive plant species are plants that invade the natural ecosystem where they are not normally found, causing substantial damage to the new One of the primary factors that led to the successful establishment of invasive alien species in the environment is the presence of rivers in these areas.
Seeds may be dispersed by wind or water, allowing them to colonize new areas rapidly.
The constant flow of water also provides an express highway for dispersing propagules downstream.
Once these plant species became established in these areas, they could outcompete native plant species and become widespread.
Invasive species, by competitive exclusion, niche relocation, or hybridization with related species, can cause the extinction of native species.
As a result, in addition to their economic consequences, such invasions can cause significant changes in the structure, composition, and global distribution of biota, resulting in the homogenization of the worldAos fauna and flora and biodiversity loss (Shuvar et al.
Invasive plant species can significantly damage the environment where they are introduced.
Invasive species can harm agriculture and society (Pratt et al.
Recent studies show that invasive plant species can cause significant damage to several sectors when successfully establishing new habitats (Shackleton et al.
Shrestha et For example, in this study.
Chromolaena odorata is considered one of the most aggressively spreading invasive weeds.
It has been designated one of the worldAos 100 worst invasive plant ItAos spread substantially threatens various ecosystems from subtropical to tropical regions (Koutika &Rainey 2.
It typically invades roadsides, fallow areas, and forest environments, establishing dense monocultures (Thapa et al.
Tiybry & Gnanazan 2.
In invaded ecosystems, the weed displaces native species, affects species composition, and severely affects livestock and agricultural fodder (Shackleton et al.
Thapa et al.
Such negative effects of odoroata on native ecosystems have become a significant environmental challenge.
Across all global regions, the number of alien plant species is continuously increasing.
riparian habitats, these populations are frequently abnormally high, seriously affecting ecosystem services and native species communities (Pabst et Various factors influence disturbanceAos function in enabling plant invasions in riparian Since riparian vegetation structure is substantially impacted by land use and land cover changes, riparian sites with a more natural land use type tend to have fewer IAPs (Zelnik et Fonseca et al.
Higher human pressures and hydrological disturbances in lowlying riparian areas produce a profusion of young, disturbed ecosystems that are more vulnerable to invasion, such as river bars (Liendo et al.
How land is used next to riparian zones affects how vulnerable the communities are to invasion (Zelnik et al.
Controlling invasive plant species in restoration areas can be accomplished through various techniques.
The most effective chemical control method relies on several elements, including the species being managed, the available funds, laws (Dechoum et al.
, and even individual Effective management initiatives have typically increased biological diversity.
However, it suggests that effective eradication may affect local species and unanticipated ecosystems.
When an invasive plant species is removed, for instance, it may result in fewer resources being available for native fauna if other restoration measures are not Furthermore, once removed, some invasive plant species may continue to impact the system because of their residual effects on the root symbiont and soil microbial communities (Koziol et al.
Ten .
species were recorded as Invasive plant species on the Global Invasive Species database, namely: Chromolaena odorata.
Elephantopus mollis.
Sphagneticola trilobata.
Ipomoea aquatica.
Leucaena leucocephala.
Pueraria montana.
Abelmoschus moschatus.
Psidium guajava.
Imperata cylindrica, and Lygodium microphyllum (Table .
On the other hand, twenty-two .
species of Invasive plants were listed in the Global Register of Introduced and Invasive Species database - Philippines Database these are Amaranthus spinosus.
Cyathula prostrata.
Ageratum conyzoides.
Chromolaena odorata.
Elephantopus mollis.
Mikania micrantha.
Pseudelephantopus spicatus.
Heliotropium indicum.
Leucaena leucocephala.
Mimosa pudica.
Senna occidentalis.
Hyptis brevipes.
Sida acuta.
Urena lobata.
Psidium guajava.
Piper aduncum.
Eleusine indica.
Imperata cylindrica.
Scoparia dulcis.
Lantana camara.
Stachytarpheta jamaicensis and Hedychium coronarium (Table .
Furthermore, five species that are common in the two databases include the Chromolaena odorata.
Elephantopus mollis.
Leucaena leucocephala.
Psidium guajava, and Imperata cylindrica (Table .
BIOTROPIA Vol.
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Table 4 Distribution of introduced plant species in the riparian areas in Northern Samar and confirmed Invasive Plant Species based on Global Invasive Species and Global Register of Introduced and Invasive SpeciesPhilippines Database Family Species Acanthaceae Amaranthaceae Apiaceae Asteraceae GISD
GIRSP
Acanthus ilicifolius L.
Odontonema cuspidatum (Nee.
Kuntze Amaranthus spinosus L.
IAS
Amaranthus viridis L.
Cyathula prostrata (L.
) Blume
IAS
Centella asiatica (L.
) Urb.
Ageratum conyzoides L.
IAS
Ageratum houstonianum Mill.
Chromolaena odorata (L.
) R.
King & H.
Rob
IAS
IAS
Cyanthillium cinereum (L.
) H.
Rob.
Eclipta prostrata (L.
) L.
Elephantopus mollis Kunth
IAS
IAS
Elephantopus tomentosus L.
Helianthus annuus L.
Mikania cordata (Burm.
) B.
H Rob.
Mikania micrantha Kunth
IAS
Pseudelephantopus spicatus (Juss.
Aubl.
) Rohr
IAS
IAS
Sphagneticola trilobata L.
Boraginaceae Heliotropium indicum L.
Commelinaceae Commelina diffusa Burm.
Convolvulaceae Ipomoea aquatica Forssk.
IAS
Cyperaceae Actinoscirpus grossus (L.
) Goetgh.
Simpson Cyperus brevifolius (Rottb.
) Endl.
Hassk.
Cyperus iria L.
Cyperus rotundus L.
Fabaceae Study Area
IAS
Scleria scrobiculata Nees & Meyen Caesalpinia pulcherrima (L.
) Sw.
IAS
Leucaena leucocephala (Lam.
) de Wit Mimosa pudica L.
IAS
Pueraria montana (Lour.
) Merr.
IAS
Senna occidentalis (L.
IAS
Gleicheniaceae Dicranopteris linearis (Burm.
Underw.
Lamiaceae Hyptis brevipes Poit.
IAS
Malvaceae Abelmoschus moschatus Medik
IAS
IAS
Sida acuta Burm.
IAS
Sida rhombifolia L.
Urena lobata L.
IAS
Melastomataceae Melastoma malabathricum L.
Myrtaceae Psidium guajava L.
IAS
IAS
Nephrolepidaceae Nephrolepis cordifolia (L.
) C.
Presl Invasive alien plant species in the riparian areas of Northern Samar.
Philippines - Abobo et al.
Family Species Study Area
GISD
GIRSP
Onagraceae Ludwigia octovalvis (Jacq.
) P.
Raven Piperaceae Piper aduncum L.
Poaceae Agrostis gigantea Roth
IAS
Arundo donax L.
Bambusa vulgaris Schrad.
Wendl Bromus inermis Leyys.
Echinochloa colonum (L.
IAS
Eleusine indica (L.
) Gaertn.
Eragrostis elongata (Willd.
) Jacq.
Eragrostis pilosa (L.
) P.
Beauv Imperata cylindrica (L.
) P.
Beauv.
IAS
IAS
Oplismenus compositus (L.
) P.
Beauv.
Oryzopsis hymenoides Ricker ex Piper Saccharum spontaneum L.
Themeda triandra Forssk.
Polygonaceae Persicaria barbata (L.
) H.
Hara Schizaeaceae Lygodium microphyllum (Cav.
) R.
IAS
Scrophulariaceae Scoparia dulcis L Solanaceae Physalis peruviana L.
Tiliaceae Triumfetta rhomboidea Jacq.
Verbenaceae Lantana camara L.
Stachytarpheta cayennensis (Rich.
Vahl
Zingiberaceae IAS
IAS
Stachytarpheta indica (L.
) Vahl.
Stachytarpheta jamaicensis (L.
) Vahl
IAS
Hedychium coronarium J.
Koenig
IAS
Notes: Sampling areas (AL = Allen.
BR = Biri.
CR = Catarman.
GM = Gamay.
PB = Pambujan.
LV = Lavezares.
LA = Laoang.
LN = Las Navas.
MP = Mapanas.
LP = Lapini.
( ) Present.
(-) Absent.
Database (GISD = Global Invasive Species Database.
GRISP = Global Register of Introduced and Invasive SpeciesAePhilippine.
CONCLUSION
REFERENCES