Conceived and designed the experiments: CB AG PP. Performed the experiments: AG PP. Analyzed the data: AG. Wrote the paper: CB AG PP.
The authors have declared that no competing interests exist.
As part of an island-wide project to identify and eradicate potentially invasive plant species before they become established, a program of inventories is being carried out in the urban and agricultural zones of the four inhabited islands in Galapagos. This study reports the results of the inventory from Puerto Villamil, a coastal village representing the urban zone of Isabela Island. We visited all 1193 village properties to record the presence of the introduced plants. In addition, information was collected from half of the properties to determine evidence for potential invasiveness of the plant species. We recorded 261 vascular taxa, 13 of which were new records for Galapagos. Most of the species were intentionally grown (cultivated) (73.3%) and used principally as ornamentals. The most frequent taxa we encountered were
Oceanic islands are particularly vulnerable to disturbance resulting from human activity
Located in the eastern Pacific Ocean, the Galapagos Islands straddle the equator, some 1000 kilometers west of the South American coast. The archipelago, of volcanic origin, is known to be one of the best preserved oceanic archipelagos in the world due to late arrival and establishment of man and is famous for the high level of endemism across all taxa–42% of the 553 native plant species are endemic. The latter group includes seven endemic genera including
In spite of the fact that 95% of the archipelago is protected as a National Park, the persistence of the native plant communities and species are increasingly at risk, owing to direct and indirect pressures from the presence and activities of humans in the islands
The complete eradication or continuous control of established invasive and aggressive plants is difficult and, when possible, implies costly long-term programs
In order to implement the early detection strategy, Randall
Previous inventories of introduced plant species in Galapagos have not been carried out in a systematic, or exhaustive fashion, and given the importance of complete reliable information for carrying out an eradication campaign, a systematic program of inventories of the introduced plants of the urban and rural zones of Galapagos was initiated in 2002.
The present study is a component of this extensive program and focuses on the introduced plants of the urban part of Isabela Island, the village of Puerto Villamil. Puerto Villamil is the largest village on the island, and thus represents a focal point for the introduction of plant species. We registered the presence and distribution of all the introduced plant species in the village, and gathered information about their phenology, reproduction and state of naturalization. Every species recorded is assessed for its potential invasibility, and both sets of information are used to develop a list of priority species for complete eradication from Isabela Island. This inventory also contributed to the Charles Darwin Research Station (CDRS) Herbarium collection with new specimens of introduced plant species.
We recorded a total of 261 vascular plant taxa in the village. All but two (identified only to genus) were identified to a species or subspecies level.
Up until the start of this study in September 2004, only 153 taxa of introduced plants had been reported for Isabela Island. Our study contributed 108 additional taxa, representing a 41.4% increase in the number of introduced taxa known from Isabela. This includes 13 new taxa for Galápagos (
Scientific name and Family | Common names English (Spanish) | Use | Growth form | Introduction status in Galapagos | Data for naturalisation assessmnent in Puerto Villamil |
h | Es | notcu, sex1, fl, fr | |||
(Cresta de pavo) | orn | sh | Cu | cu, fl | |
(Cola de Zorro, Rabo de mono) | orn | sh | Cu | cu, fl | |
orn | sh | Cu | cu, fl | ||
Yarrow | orn | h | Es | Cu | |
h | Ac | notcu | |||
Century Plant (Cabuya negra, Penco) | orn | s | Cu | cu | |
orn | s | Cu | cu, asex2 | ||
orn | h | Cu | Cu | ||
Yellowbell (Campana de oro, Copa de oro) | orn | v | Cu | cu, fl | |
Onion, Spring onion (Cebolla paiteña, Cebolla blanca) | edi | h | Cu | Cu | |
Garlic (Ajo) | edi | h | Cu | ||
Chives (Cebollín) | edi | h | Cu | Cu | |
(Camacho) | orn | h | Cu | cu, asex2 | |
(Sábila de Castilla) | orn | s | Cu | Cu | |
orn | s | Cu | cu, asex2 | ||
(Sabila) | med | s | Cu | cu, asex2, fl, fr | |
(Pata de paloma) | orn | h | Cu | Cu | |
(Sangoreche verde, Quinoa) | med | h | Cu | cu, notcu, fl, fr | |
▸ | h | Ac | notcu, sex1, fl, fr | ||
▸ | h | Ac | notcu, sex1, asex1, fl, fr | ||
h | Ac | notcu, fl, fr | |||
Pineapple (Piña) | edi | s | Cu | Cu | |
Cherimoya (Chirimoya) | edi | sh | Es | ||
▸ | Pond Apple (Anona) | t | NaQ | notcu, sex1, asex1, fl, fr | |
Soursop (Guanábana) | edi | t | Es | cu, fr | |
Coral Vine (Corazon bello) | orn | v | Es | cu, fl, fr | |
Celery (Apio) | edi | h | Cu | ||
orn | s | Cu | cu, asex2, fl, fr | ||
Foxtail Fern | orn | v | Es | cu, fl, fr | |
Asparagus Fern (Creston) | orn | v | Es | Cu | |
Orchid Tree (Orquidea del pobre) | orn | t | Cu | cu, notcu, sex2, fl, fr | |
(Acelga) | edi | h | Cu | Cu | |
Beetroot (Remolacha) | edi | h | Cu | ||
(Amor seco) | h | NaQ | Notcu | ||
h | Ac | Notcu | |||
h | NaQ | notcu, sex1, fl, fr | |||
(Bouganvilla, Veranera) | orn | sh | Cu | cu, fl | |
orn | s | Cu | Cu | ||
(Nabo) | edi | h | Cu | ||
Cauliflower (Coliflor) | edi | h | Cu | cu, fl | |
Cabbage (Col) | edi | h | Cu | cu, fl | |
Broccoli (Brócoli) | edi | h | Cu | cu, fl | |
h | Es | notcu, fl, fr | |||
(Arbolito de navidad) | orn | sh | Cu | cu, sex2, asex2, fl, fr | |
(Floripondio, Guanto) | orn | sh | Es | cu, fl | |
orn | s | Cu | cu, asex2 | ||
orn | s | Cu | cu, sex2, asex2, fl, fr | ||
▸ | Mother-of-Thousands (Hoja del aire) | orn-med | s | Es | cu, notcu, asex1, fl |
Barbados Cherry (Cereza, Nicaragua) | orn | sh | Cu | cu, fr | |
▸ | (Mora) | sh | NaQ | notcu, sex1, fl, fr | |
Pride of Barbados | orn | sh | Es | cu, sex2, fl, fr | |
Elephant's Ears (Corazón de Jesús) | orn | h | Cu | Cu | |
Indian Shot (Achira) | orn | h | Cu | cu, asex2 | |
(Atzera, Platanillo) | orn | h | Es | cu, asex2, fl, fr | |
Sweet Pepper (Aji, Pimiento) | edi | h | Cu | cu, fl, fr | |
Chili (Ají) | edi | h | Es | cu, fl, fr | |
(Pata de langosta) | orn | s | Cu | cu, asex2 | |
▸ | Pawpaw, Papaya (Papaya) | edi | t | Es | cu, notcu, sex1, sex2, fl, fr |
▸ | Madagascar Periwinkle (Chavelas) | orn | h | Es | cu, notcu, sex1, asex1, sex2, asex2, fl, fr |
Cotton Tree (Ceibo) | orn | t | Cu | cu, fr | |
(Cresta de gallo, Rabo de conejo) | orn | h | Cu | cu, fl | |
(Cresta de gallo) | orn | h | Cu | cu, sex2, asex2, fl, fr | |
▸ | h | Ac | notcu, sex1, asex1, fl, fr | ||
orn | h | Es | cu, fl, fr | ||
orn | s | Cu | cu, asex2 | ||
orn | s | Cu | Cu | ||
▸ | h | Ac | notcu, sex1, asex1, fl, fr | ||
▸ | Wormseed, Mexican Tea (Paico) | med | h | Es | cu, notcu, sex1, sex2, fl, fr |
▸ | h | Ac | notcu, sex1, fl, fr | ||
(Mala madre) | orn | h | Cu | cu, fl | |
Watermelon (sandía) | edi | v | Es | cu, notcu, fl, fr | |
(Citrón) | edi | t | Cu | Cu | |
Tangerine, Mandarin (Mandarina fina) | edi | t | Cu | Cu | |
(Limón-mandarina) | edi | t | Cu | cu, fl, fr | |
Lime (Limón, Limón verde) | edi | t | Es | cu, asex2, fl, fr | |
Lemon (Limón amarillo, Limón sútil) | edi | t | Es | cu, fl, fr | |
Grapefruit (Toronja) | edi | t | Cu | cu, notcu | |
Sweet Orange (Naranja dulce) | edi | t | Cu | Cu | |
Bleeding Hearts | orn | v | Cu | cu, fl | |
(Coco) | edi-orn | t | Cu | cu, fl, fr | |
Croton (Espelma, Croton) | orn | sh | Cu | cu, fl | |
h | Ac | notcu, fl, fr | |||
h | Ac | notcu, fl | |||
orn | sh | Cu | cu, asex2 | ||
Coriander (Cilantro) | edi | h | Cu | cu, fl, fr | |
Lesser Swine-cress (Mastuerzo) | h | Ac | notcu, sex1, fl, fr | ||
(Lirio de cinta) | orn | h | Cu | Cu | |
▸ | (Huevo de tigre) | v | AcQ | notcu, sex1, fl, fr | |
Melon (Melón) | edi | v | Cu | cu, fl, fr | |
Cucumber (Pepino) | edi | v | Cu | cu, fl | |
Pumpkin, Winter Squash (Zapallo) | edi | v | Cu | cu, notcu, fl, fr | |
Courgette, Marrow (Zucchini) | edi | v | Cu | Cu | |
h | AcQ | notcu, fl, fr | |||
Lemon Grass (Hierba luisa) | med | h | Cu | cu, asex2 | |
▸ | Couch | h | Es | cu, notcu, sex1, asex1, sex2, asex2, fl, fr | |
h | Ac | notcu, fl, fr | |||
▸ | (Sombrilla) | orn | h | Es | cu, notcu, asex1, asex2, fl, fr |
h | Ac | notcu, asex1, fl, fr | |||
Dahlia (Dalia) | orn | h | Cu | cu, fl, fr | |
orn | ssh | Es | notcu, fl, fr | ||
▸ | orn | h | Cu | cu, notcu, sex1, sex2, fl, fr | |
Carrot (Zanahoria) | edi | h | Cu | cu, fl | |
Flame Tree, Flamboyant (Falsa acacia) | orn | t | Es | cu, notcu, sex1, sex2, fl, fr | |
Chrysanthemum (Pomo) | orn | h | Cu | cu, fl | |
Dumb Cane (Millonaria, Chucha) | orn | h | Cu | Cu | |
orn | h | Cu | cu, asex2 | ||
h | NaQ | sex1 | |||
h | Ac | notcu, fl | |||
▸ | h | Ac | notcu, sex1, fl, fr | ||
orn | ssh | Cu | |||
orn | ssh | Cu | Cu | ||
orn | ssh | Cu | Cu | ||
Golden Cane Palm (Palma enana) | orn | t | Cu | Cu | |
orn | s | Cu | Cu | ||
orn | s | Cu | Cu | ||
orn | s | Cu | |||
▸ | h | NaQ | notcu, sex1, asex1, fl, fr | ||
▸ | h | Ac | notcu, sex1, asex1, fl, fr | ||
(Vara de justicia) | orn | h | Cu | cu, asex2 | |
(Galan de noche) | orn | s | Cu | Cu | |
(Enredadera, Cortina) | orn | v | Cu | cu | |
▸ | h | Ac | notcu, sex1, fl | ||
(Porotillo) | oth | t | Cu | Cu | |
orn | h | Cu | Cu | ||
orn | h | Cu | notcu, fl | ||
▸ | orn | h | Es | cu, notcu, sex1, sex2, fl, fr | |
▸ | Grassleaf Spurge | h | Ac | notcu, sex1, fl, fr | |
Mexican Fire Plant, Wild Poinsettia | h | Es | |||
orn | ssh | Cu | Cu | ||
Crown of Thorns (Corona del Señor, Corona de Cristo) | orn | ssh | Cu | Cu | |
Poinsettia (Flor de Pascua/Panamá) | orn | sh | Es | Cu | |
(Ficus) | orn | t | Cu | Cu | |
Edible Fig (Higo) | edi | sh | Cu | cu, fl, fr | |
(Caucho) | orn | t | Cu | Cu | |
▸ | (Cabuya, Penco blanco) | orn | s | Es | cu, sex2, fr |
orn | h | Cu | cu, fl | ||
(Alivia dolor, Cura todo) | med | h | Es | cu, asex2, fl | |
(Mata Raton, Madero Negro, Nacedero) | oth | t | Cu | cu, notcu, sex2, fl, fr | |
orn | s | Cu | cu, asex2, fl | ||
Sunflower (Girasol) | orn | ssh | Cu | cu, fl, fr | |
(Espiga de San Antonio) | orn | h | Cu | ||
Monarch Rosemallow (Amapola) | orn | h | Es | cu, notcu, sex1, sex2, asex2, fl, fr | |
(Peregrina) | orn | sh | Es | cu, fl, fr | |
(Peregrino) | orn | sh | Cu | cu, fl | |
Amaryllis | orn | h | Cu | cu, asex2 | |
orn | h | Cu | Cu | ||
Amaryllis (Amarilis) | orn | h | Cu | cu, fl | |
(Hoja de cera) | orn | s | Cu | ||
orn | s | Cu | Cu | ||
Hydrangea (Hortensia) | orn | ssh | Cu | cu, fl | |
orn | ssh | Es | cu, asex2, fl | ||
Spider Lily | orn | h | Cu | cu, notcu | |
(Guava (bejuco), Guava de mico) | edi | t | Es | cu, fl, fr | |
Sweet Potato (Camote) | edi | v | Es | cu, asex2, fl | |
orn | v | Cu | |||
(Piñon) | oth | sh | Es | cu, fl, fr | |
orn | s | Cu | cu, asex2, fl, fr | ||
orn | s | Cu | |||
orn | s | Es | cu, asex2 | ||
▸ | Henna (Reseda) | orn | h | Cu | cu, notcu, sex1, fl, fr |
(Ipel ipel) | sh | Es | cu, fl | ||
edi-orn | t | Cu | cu, fl | ||
▸ | h | Ac | notcu, sex1, fl, fr | ||
orn | sh | Cu | cu, fl, fr | ||
Mango (Mango) | edi | t | Es | cu, fl, fr | |
Cassava, Manioc (Yuca) | edi | sh | Cu | Cu | |
Chamomile (Manzanilla) | med | h | Cu | cu, fl | |
Stock | orn | h | Cu | cu, notcu, sex2, asex2, fl, fr | |
Alfalfa, Lucerne (Alfalfa) | med | h | Cu | ||
Chinaberry, Persian Lilac (Jasmin de Arabia, San Jacinto) | orn | t | Es | cu, fl, fr | |
Peppermint (Menta, Hierbabuena) | med | h | Es | cu, asex2, fl, fr | |
Marvel of Peru, Four O'Clock Plant (Buenas tardes) | orn | h | Es | notcu, fl, fr | |
Banana (Guineo) | edi | h | Cu | cu, asex2 | |
orn | h | Cu | cu, fl | ||
orn | h | Cu | cu, asex2 | ||
orn | h | Cu | cu, asex2 | ||
orn | h | Cu | Cu | ||
Oleander (Laurel) | orn | sh | Cu | cu, fl, fr | |
Basil (Albaca) | edi | h | Cu | cu, fl, fr | |
orn | sh | Es | cu, fl | ||
orn | s | Cu | Cu | ||
orn | s | Cu | Cu | ||
orn | s | Cu | Cu | ||
Prickly Pear | orn | s | Es | Cu | |
orn | s | Cu | Cu | ||
Orégano (Oregano) | edi | h | Cu | cu, asex2 | |
h | AcQ | notcu, sex1, asex1, fl, fr | |||
▸ | Saltwater Couch | h | Na | notcu, sex1, asex1, fl, fr | |
▸ | Maracuya (Maracuyá) | edi | v | Es | cu, notcu, sex1, fl |
(Zapatillas rojas) | orn | ssh | Cu | cu, asex2, fl | |
(Malva olorosa, Esencia de rosa) | orn-med | h | Cu | Cu | |
Geranium (Geranio) | orn | h | Cu | cu, fl, fr | |
Elephant Grass (Pasto elefante) | h | Es | Cu | ||
orn | h | Cu | Cu | ||
Parsley (Perejil) | edi | h | Es | Cu | |
Butter Bean, Lima Bean (Habichuela) | edi | v | Cu | cu, fl, fr | |
(Fréjol, Vainita) | edi | v | Cu | Cu | |
Date Palm (Dátil) | orn | t | Cu | Cu | |
(Grosella) | edi | t | Cu | cu, sex2, fl, fr | |
▸ | Greater Plantain (Llanten) | med | h | Ac | cu, notcu, sex1, asex1, sex2, fl, fr |
(Oreganón, orégano) | edi | h | Cu | cu, asex2 | |
orn | sh | Cu | Cu | ||
orn | sh | Cu | Cu | ||
▸ | (Ruda gallinazo) | h | Ac | notcu, sex1, fl, fr | |
(Flor de un día) | orn | s | Cu | cu, asex2, fl, fr | |
▸ | Purslane (Verdolaga) | med | s | NaQ | notcu, sex1, asex1, fl, fr |
orn | s | Cu | cu, sex2, asex2, fl, fr | ||
orn | s | Na | cu, asex2, fl, fr | ||
orn | t | Cu | Cu | ||
(Cadillo) | h | Ac | notcu, sex1, fl, fr | ||
orn | sh | Cu | cu, fl | ||
Guava (Guayabo) | edi | t | Es | cu, notcu, fr | |
orn | t | Cu | cu, fl, fr | ||
Pomegranate (Granada) | edi | sh | Cu | cu, fl, fr | |
Radish (Rábano) | edi | h | Es | cu, fl, fr | |
▸ | Castor Oil (Higuerrilla) | ssh | Es | notcu, sex1, fl, fr | |
Rose (Rosa) | orn | ssh | Cu | cu, fl | |
Royal Palm (Palma real) | orn | t | Cu | ||
orn | h | Es | cu, notcu, sex2, asex2, fl, fr | ||
(Lluvia de fuego, Lluvia de coral) | orn | sh | Cu | cu, fl, fr | |
Rue (Ruda) | med | ssh | Cu | cu, | |
Sugarcane (Caña de azucar) | edi | h | Cu | cu, asex2 | |
Mother-in-law's Tongue (Lengua de suegra) | orn | h | Es | cu, asex2, fl | |
(Cheflera) | orn | ssh | Cu | cu, | |
▸ | (Palo de abejón) | orn | ssh | Es | cu, notcu, sex1, fl, fr |
(Dormidera) | h | Ac | notcu, | ||
▸ | (Escoba negra) | h | Ac | notcu, sex2, fl | |
▸ | h | Ac | notcu, sex1, fl, fr | ||
▸ | (Escobilla) | h | Ac | notcu, sex1, fl, fr | |
▸ | Black Nightshade (Hierba mora) | med | h | NaQ | notcu, sex1, fl, fr |
Tree Tomato, Tomatillo (Tomate de arbol) | edi | sh | Cu | ||
orn | h | Cu | cu, notcu, fl, fr | ||
Tomato (Tomate riñon) | edi | h | Es | cu, notcu, sex1, sex2, asex2, fl, fr | |
Aubergine, Garden Egg, Eggplant (Berenjena) | edi | sh | Cu | ||
h | Es | notcu, sex1, fl, fr | |||
Lulo (Naranjilla) | edi | sh | Es | ||
Potato (Papa) | edi | h | Cu | cu, notcu | |
(Coleos) | orn | h | Cu | Notcu | |
Spinach (Espinaca) | edi | h | Cu | Cu | |
(Ciruelo) | edi | t | Es | cu, fl, fr | |
Mahogany (Caoba) | oth | t | Cu | cu, fl, fr | |
▸ | h | Ac | notcu, sex1, fl, fr | ||
orn | v | Cu | Cu | ||
orn | h | Cu | cu, fl, fr | ||
Tamarind (Tamarindo) | edi | t | Cu | cu, fl, fr | |
Dandelion (Taraxaco, Diente de león) | med | h | AcQ | Cu | |
Indian Almond (Almendro) | orn | t | Cu | cu, sex2, fl, fr | |
(Ciprés) | orn | t | Cu | ||
orn | h | Cu | cu, asex2 | ||
▸ | (Cacho de chivo) | v | NaQ | notcu, sex1, asex1, fl, fr | |
(Cacho de chivo) | v | NaQ | notcu, fl, fr | ||
Nasturtium (Mastuerzo) | med | v | Cu | cu, fl | |
Cowpea, Black-eyed Bean (Verdura, Fréjol chileno) | edi | v | Cu | cu, fl, fr | |
Grape (Uva) | edi | v | Cu | Cu | |
(Otoy) | orn | h | Es | cu, asex2 | |
(Flor de novia, Peine de indio) | orn | sh | Cu | cu, asex2, fl | |
(Cartucho) | orn | h | Cu | ||
Maize (Mais) | edi | h | Cu | cu, fl | |
orn | h | Cu | cu, asex2, fl, fr | ||
▸ | (Césped chino) | orn | h | Es | cu, notcu, sex1, asex1, sex2, asex2, fl, fr |
indicates a new record for Galapagos,
indicates a new record for Isabela Island
The five most frequently recorded species were
The number of taxa recorded in each neighborhood reflected the dynamics of colonization as well as the activity of the dwellers (
Numbers above the bar indicate the number of properties surveyed in each neigbourhood. The neighbourhoods are organized by time since establishment with oldest neighborhoods on the left.
Almost half (43.2%) of the selected properties had no introduced plants present, most of these occurring in neighbourhoods that have been established in the last 5 years. The neighborhoods of
The majority of the introduced plants in Puerto Villamil (82% of all taxa) were given a use. The principal use was ornamental (50% of all taxa), followed by food (22%), medicinal (5%) and mixed uses (5%) such as shade or fence plants in addition to the previous uses.
The most frequent growth form was the herbaceous form (48% of all taxa) followed by tree and succulent (each one 13%), shrub (12%), vine (9%) and subshrub (6%) (
Of 236 taxa analysed, 167 taxa (70.8%) were being cultivated and 52 taxa (22.0%) not cultivated. The remaining 17 taxa (7.2%) were both cultivated and not cultivated. Forty four ornamental taxa were found to be regenerating without human assistance.
An analysis of naturalization identified 39 taxa as being completely naturalized in Puerto Villamil, with additional taxa in initial phases of naturalization.
Although we did not detect any species displaying invasive behavior within the urban perimeter, it revealed three other important groups of plants:
Species that have recently started to display an invasive behavior in the village but for which eradication will be difficult as their growth form prevents easy identification (e.g. species within the family Poaceae), or the plants are of importance to their owners as an ornamental. This group includes
Species with a limited distribution in the village but which are already recognized as aggressive invaders in nearby areas of the Galapagos National Park or in the rural zone Isabela, making the feasibility of their eradication from the Island difficult. This group includes
Species with a limited distribution in Isabela but that are recorded from elsewhere as being aggressive, and thus should be prioritized for eradication. This last group includes six species that we recommend as candidates for eradication:
There are four steps in the battle against introduced species: prevention, early detection, eradication and control
The field work was carried out during five weeks, between October 2004 and April 2005 and a last visit in September 2005.
All properties/lots in Puerto Villamil (1193 lots) were visited, 597 of them for complete inventory (selected lots) and 596 only for detection of additional species (non-selected lots).
Located on the western side of the Galápagos, Isabela is the largest island of the archipelago. The village of Puerto Villamil is situated along the southern coast, on a wide east-west barrier beach, met to the north by fields of basaltic lava from Sierra Negra Volcano. The semi-arid, subtropical climate is dominated by cold ocean currents driven by southeast trade winds, with two seasons, a dry and cool season from June to December and a wet and warm season from January to June. The overall variation of the air temperature is low. In Puerto Villamil, means ranging from 19 to 26°C have been registered during the cool season and from 22 to 30°C in the warm season. Precipitation averages 11 mm per month in the garua season and 48 mm per month in the hot season, except in El Nino years where the rainfall is much higher.
Even though Isabela was visited earlier it was truly colonized in 1897 by Antonio Gil who founded the village of Puerto Villamil, and then established a farm in the humid zone, on the slope of Sierra Negra. The annual growth rate of Isabela's population almost doubled between the 1980s (3.7%) and the 1990s (6.4%), a total of 1749 inhabitants being registered in the 2006 census; most of them live in the village
This study centered on the urban administrative territory of Southern Isabela referred to as Puerto Villamil. It covers an area of 125.2 ha and is composed of 1193 properties, grouped into 134 blocks, and forming ten neighborhoods (
Every property of the village was visited in order to register the presence of all the introduced species of vascular plants in the urban zone. Out of each block, five properties were randomly selected. In each of these, all the species of introduced plants were recorded and additional information to be used later in a weed risk assessment collected (see details below). The other properties were also visited to register any additional species not already encountered in the selected lots. The geographical coordinates of the lots and of new species were also recorded.
In order to determine the actual or potential invasiveness of each species, the following ecological, biological, ethno-botanical and socio-geographical aspects were recorded:
tree-a woody plant with generally one major trunk,
shrub-a woody plant with several stems, usually shorter than a tree,
subshrub, a plant with some woody growth, intermediate between herb and shrub,
herb, a plant with little or no woody growth,
vine, a woody or non-woody plant which cannot stand freely,
succulent, a xerophytic plant with fleshy or succulent stems and/or leaves
aquatic
Our most sincere thanks to all the inhabitants of Puerto Villmill who so willingly let us carry out a vegetation survey on their properties, and who provided us with extra information on use of the species; to Vicente Freire for providing cartographical material as well as historical data, to Agnes and Vincent for sharing with us their experience and studies.
We wish to thank all the personel of the Galapagos National Park Service in Isabela, especially Juan Chavez for his advice, as well as Pedro Ramón, Don Cañita, Edison Encalada, Don Pedro and Luis Gil. We would also like to thank Johana Mader for her help with the analysis.
The opinions expressed herein belong to the authors and do not necessarily reflect the opinions of GEF/UNDP.