Invasive plants in Mediterranean type regions of the world ... - Lipor

Invasive plant species in Portugal: an overview
Hélia Marchante1, Elizabete Marchante2, Helena Freitas2
1 Sector de Biologia e Ecologia, Escola Superior Agrária de Coimbra, 3040-316 Coimbra,
Portugal
2 Departamento de Botânica, Universidade de Coimbra, 3049 Coimbra, Portugal
Email: hmarchante@esac.pt
Abstract
The invasion by exotic plants is threatening the Portuguese native flora becoming a
serious environmental problem. In the last two centuries, and especially in recent
decades, the number of introduced plant species increased extensively with aliens
representing nowadays more than 15 % of a total of ca. 3200 taxa of the Portuguese
vascular flora. Their presence has increased probably more than 1000 % during the
last two centuries, reaching nowadays the worrying figure of about 500 species.
Almost 40 % of the listed species are actually or potentially invasive, including
agricultural weeds and invaders of natural habitats, and ca. 7% are considered
dangerous invaders. Leguminosae and Asteraceae provide the largest numbers of
problematic species. Australia seems to supply the most dangerous and aggressive
invaders in Portugal, including several Acacia and Hakea species. From different
origins and taxonomies Ailanthus altissima and Cortaderia selloana also worth special
attention due to the current drastic increase in their distribution.
Recently, Portuguese legislation has recognised this problem (dec.- lei 565/99),
creating a list of the exotic species introduced, identifying the invasive ones, and
forbidding the introduction of new species unless proven not harmful. Although this
list does not include all the species introduced and despite the fact that there are
exceptions for forestry and agricultural purposes, it is a good starting point. The
legislative process is still being implemented and will apply penalties to the use of
listed invasive species. As next steps, the list needs updating and it is essential to
implement the regulations in the field with inspections to horticulturist, landscape
architectures, gardeners, boarders and others. Technician‘s training is still needed to
assure the correct application of the legislation.
Introduction
The invasion by exotic plants is threatening the Portuguese native flora and becoming a
serious environmental problem (Almeida & Freitas 2001, Campelo 2001, Marchante 2001;
Almeida & Freitas, in press). In the last two centuries, and especially in recent decades, the
number of introduced plant species increased extensively with aliens representing nowadays
more than 15 % of a total of ca. 3200 taxa of the Portuguese vascular flora (Almeida 1999).
Their presence has increased probably more than 1000 % during the last two centuries, from
33 known sub-spontaneous species in 1800 reaching in 2005 the worrying figure of about
550 species (Almeida & Freitas, in press) and still increasing (Figure 1). This data should be
seen as conservative with new introductions in ornamental sector being frequent and often
difficult to track. Almost 40 % of the listed species are actually or potentially invasive,
including agricultural weeds and invaders of natural habitats, and ca. 7% are considered
dangerous invaders. Fabaceae and Asteraceae provide the largest numbers of problematic
species. Australia seems to supply the most dangerous and aggressive invaders in Portugal,
including several Acacia and Hakea species.
99

no of species
Figure1. Increase of exotic plant
species introduced in Portugal since
1500 (based on Almeida 1999;
Almeida & Freitas, in press).
Some of the worst examples of
species responsible for threatening
the Portuguese native flora (Table
I) are given by species of the
genus Acacia (Marchante et al. 2003), Hakea and Carpobrotus (Pinto da Silva et al. 1989,
Campelo 2001); Ailanthus altissima and Cortaderia selloana also worth special attention
due to the current drastic increase in their distribution. The big spread of some of these
species, namely the ones with tree habit, has already displaced large areas of native
vegetation, including several areas with conservation interest which preservation is
nowadays seriously threatened.
Table I. Some of the worst and more aggressive invasive plant species present in Portugal
Family Species Introd.purpose Habitats invaded
Aizoaceae
evolution of exotic plant species in Portugal
600
500
400
300
200
100
0
1500 1600 1700 1800 1850 1900 1950 2005
Carpobrotus edulis (L.) N.E.
Br.
(South Africa)
Apiaceae Eryngium pandanifolium
(Umbelliferae) Cham. & Schlecht……………
……………..(South America)
Commelinaceae Tradescantia fluminensis
Velloso (South America)
Convolvulaceae Ipomoea acuminata (Vahl)
Roem.&Sch.(Tropical regions)
Haloragaceae Myriophyllum aquaticum
(Vel.) Verdc. (South America)
Fabaceae Acacia dealbata Link……
(SE Australia and Tasmania)
(Leguminosae) Acacia melanoxylon R. Br.
(SE Australia and Tasmania)
Pittosporaceae
Poaceae
(Gramineae)
Pontederiaceae
Proteaceae
Simaroubaceae
Acacia longifolia (Andrews)
Willd. (Australia)
Robinia pseudoacacia L.
(eastern North America)
Pittosporum undulatum Vent.
(Australia)
Cortaderia selloana (Schultes
& Schultes fil.) Ascherson &
Graebner (South America)
Eichhornia crassipes (C.F.P.
Mart.) Solms-Laub. (Tropical
South America)
Hakea sericea Schrad.
(Eastern Australia)
Hakea salicifolia (Vent.) B.L.
Burtt
(SE Australia and Tasmania)
Ailanthus altissima (Miller)
Swingle (China)
ornamental and
to fix sand dunes
and slopes
ornamental
ornamental
Ornamental
accidental
introduction
slopes stability
and ornamental
ornamental;
forestry, shadow
curb sand erosion;
ornamental
forestry,
ornamental and
soil stabilization
ornamental and
shelter
Ornamental
Ornamental
ornamental and
quickset hedges
ornamental;
wind break
especially near
the coast
Ornamental
coastal sand dunes, capes
and next to slopes where it
was planted
near waterlines in the low
Mondego Basin
shadow and humid areas;
managed woods understory
large carpets in disturbed
habitats and slopes
aquatic habitats
mountain areas, roads and
river margins;
along roads, and mountain
areas adjacent to where it
was planted
coastal areas (sand dunes
and capes); along rivers; …
near rivers and roads;
pinewoods and disturbed
lands
managed areas where it was
planted as ornamental
spreading in some dune
systems and along roads/
highways/ rails or other
water-courses and lagoons
pinewoods and disturbed
lands; isolated individuals in
relatively pristine places
coastal areas (sand dunes),
mountain areas where it was
planted and disturbed lands
spread mainly in urban areas
and in road sides
100

Portuguese legislation
Early in 1974, a first law (decreto-lei 165/74 de 22 Abril) recognized water-hyacinth
(Eichhornia crassipes) as an invasive species, forbidding its importation, culture, selling,
transport or possession. In 1999, the Portuguese law has recognized in a more wide-range the
problem of invasive species (decreto-lei 565/99 de 21 de Dezembro), creating a list of the
exotic species introduced, identifying the invasive ones, and forbidding the introduction of
new species unless proven not harmful. This regulation was the result of the international
commitment assumed when Portugal approved, for ratification, the Bern Convention
(decreto-lei n.º 95/81, de 23 de Julho), the Bone Convention (decreto-lei n.º 103/80, de 11 de
Outubro) and the Convention of Biodiversity (decreto-lei n.º 21/93, de 21 de Junho), all
suggesting the adoption of measures limiting the deliberate introduction and preventing the
accidental introduction of invasive species, as well as the control or eradication of the
invasive species already introduced. A previous law from 1987 (Lei de Bases do Ambiente:
decreto-lei n.º 11/87, de 7 de Abril) on article 15, no. 6, demanded the elaboration of
adequate legislation to regulate the introduction of exotic plant species, and on article 16, no.
3 the adoption of measures of effective control of the introduction of any wild animal species
both aquatic and terrestrial. The recent legislation was drawn to operate as a clean list
approach, meaning that every exotic species currently in the country should be listed in the
law and to introduce any other species an authorization should be asked.
The legislation was prepared by ICN (Institute of Nature Conservation, Ministry of
Environment) and DGF (Forestry National Services), with the collaboration of the scientific
community, namely to set up the species list.
The list of invasive plants
The law includes 3 separated lists of species each presented as an annex: annex I, lists the
non indigenous plant and animal species introduced in Portugal, and identifies those
considered invasive; the non invasive species are called indigenous in what concerns the
application of this law! annex II, lists non indigenous species that are considered of interest
for gardening and forestry; these species are also considered indigenous in terms of the
application of this law! annex III, list the non indigenous species that already have
ecological risk elsewhere but are not yet invasive in Portugal.
Calling “indigenous” to all the species that are not listed as invasive or do not hold
ecological risk could lead to some misinterpretation; particularly in the frequents occasions
along the text when the non indigenous species are referred, not becoming obvious which
species are in fact included or not.
The content of the law
The law limits the intentional introduction of exotic species in nature even if the aim is not to
release it. Nevertheless, due to economical reasons, exceptions are considered to species
used in agriculture (agriculture, horticulture and zootechnic). In practice, and particularly
considering both invasive (annex I. pointed as invasive) and species with ecological risk
(annex III), it specifically prohibits: 1) its cultivation, growth, maintenance in confined
place, utilization as ornamental plant or pet; and 2) to give, to buy, to sell, and to transport
specimens of those species except when they are dead and do not hold any viable propagule.
Exceptions are considered to scientific and educational purposes, as long as legally
authorized by ICN.
Other exceptions are considered when proposing the introduction of a new species: 1) when
it is proved to have unequivocal advantages to men of natural biocenosis; 2) when there is no
native species that fit to the same purpose; 3) when the introduction is preceded by a
rigorous study of impacts whose results will be relevant to the authorization. This study,
101

additionally to biological and ecological characterization, can include controlled experiments
under confinement which should be controlled by an administrative entity. The authorization
or rejection of introduction depends on the final evaluation of this entity.
Exceptions are not to be allowed if the area where the species is meant to be introduced
includes a protected area, a zone of special protection, a Natura 2000 site, an island without
human population or natural lagoons. In these particular cases, it will only be allowed if the
species is the only viable option to nature conservation or if human health or safety depends
on it.
Field impacts of the application of the law
Entities such as botanical gardens, nurseries, greenhouses, plant shops, pet shops, zoological
parks, circus, game parks, etc. need to request a license to ICN to detain non indigenous
species specifying the list of the species already detained. Other legislation (ex. CITES)
should also be respected. If the license is conceded, regular visits from environmental bureau
(including ICN) or other people with specific competences (governmental institutions
particularly responsible by agriculture, forestry, veterinary, fishing and aquaculture, and
police force entities), should be forecasted to check the safety conditions of the places that
detain the species, and to check updating of the species list.
Places that commercialize exotic plant and/or animals should expose to the public a synopsis
of this law (published as annex 4).
When a new species (theoretically all the species not included in annex I, II or III) is to be
introduced an authorization should be requested to ICN. When the species to introduce is
destined to be used as forestry or synergetic the authorization has to be asked to DGF,
consulting the ICN. To prevent accidental introductions the species should be submitted to
quarantine following rules imposed in ICN or DGF proposals.
Other technical-scientific and administrative tasks contemplated in this legislation should be
assured by ICN, sometimes with collaboration from DGF.
Penalties are considered from 150€ to 45000€ to be paid for faults that could include the
detention of an invasive species or the nonexistence of the license to detain the non
indigenous species, and it varies if being a private person or collective entity. The penalties
could also include interdiction of the permit to keep the profession or activity; or closing a
commercial establishment.
How is the law seen by people that deal with exotic species
It is not! In a recent preliminary query to horticulturists, pet shops and gardening centers,
simple questions were asked about their knowledge regarding this legislation and its
implications. Most of the answers revealed the lack of information about it!
Theoretically, the places that detain exotic species should have asked for a license and sent a
list of the non indigenous species detained to ICN from edition of the law to 6 months
after… we believe it never happened…
Next steps and suggestions
Some species were missing in all 3 annex right from the beginning, and now, 6 years after,
the lists are far from being complete (figure 2) and need to be updated; new introductions,
mainly due to ornamental purpose, species shifting category, namely species becoming new
invaders, and some synonym inaccuracy are already numerous and should be altered.
It is essential to implement the regulations in the field with a strong effort on informing
citizens directly involved and implementing inspections to horticulturist, pet shops, garden
centers, boarders and others. Technician‘s training is still needed to assure the correct
application of the legislation, namely in differentiating all the species listed.
102

no.of species
600
400
200
exotic plant species in Portugal
0
410
500
potencially invasive
unkown potencial
invasive 550
totals
decreto 565/99 Almeida 1999 this work
Figure 2. Exotic plants species
categorized according to its
invasiveness in Portugal,
following
different
bibliographic sources: the
legislation (dec.565/99),
Almeida (1999), and a brief
update prepared to this work.
To facilitate the evaluation, when someone asks for authorization to introduce a new species,
this legislation could consider a quicker way to first assess its weedy potential. For instance,
a numerical score (like Australian legislation) including plant’s prior history of weediness,
climate preferences, biological, reproductive and dispersal traits. Each new species to be
introduced would be scored by expertise’s and according to the result it would have a “yes”
or “no” quick answer, or could demand some tests.
Acknowledgement
To Mário Reis (ICN), for constructive discussions about the decreto-lei 565/99.
References
Almeida, J.D. 1999. Flora exótica subespontânea de Portugal continental (plantas
vasculares). 2.ª edição. Catálogo das plantas vasculares exóticas que ocorrem
subespontâneas em Portugal continental e compilação de informações sobre estas plantas.
Dissertação de Mestrado. Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
Almeida, J.D. & H. Freitas. 2001. The exotic and invasive flora of Portugal. Bot.
Complutensis 25: 317-327.
Almeida, J.D. & H. Freitas. The exotic and invasive flora of Portugal: a reassessment Bot.
Complutensis (in press).
Campelo, F. 2001. Estudo da exótica Carpobrotus edulis em ecossistemas dunares
Portugueses. Dissertação de Mestrado. Faculdade de Ciências e Tecnologia da Universidade
de Coimbra.
Marchante, H. 2001. Invasão dos ecossistemas dunares portugueses por Acacia: uma ameaça
para a biodiversidade nativa. 2001. Dissertação de Mestrado. Faculdade de Ciências e
Tecnologia da Universidade de Coimbra.
Marchante, H; Marchante, E & Freitas, H. 2003. Invasion of the Portuguese dune ecosystems
by the exotic species Acacia longifolia (Andrews) Willd.: effects at the community level. In:
Child, L.E.; Brock, J.H.; Brundu, G; Prach, K.; Pysek, P.; Wade, P.M. e Williamson, M.
Plant Invasions: Ecological Threats and Management Solutions. Pp. 75-85. Backhuys
Publishers. The Netherlands. Pp.75-85.
Ministério do Ambiente. 1999. Decreto-lei n.º 565/99 de 21 de Dezembro. In: Diário da
República - I Série – A. 295: 9100-9114.
Pinto da Silva, A.R., J.J.A.H. de Bacelar, F.M. Catarino, A.I.D. Correia, A.S.C. Escudeiro
M.G. Leitão Serra & C.M.A. Rodrigues. 1989. A flora da Serra de Sintra. In Portug. Acta
Biol. (B) 15: 5-258.
103