László Udvardy

University of Horticulture and Food Industry Department of Botany Hˆ1118 Budapest, Ménesi út 44
Hungary
Phone: + 36 1 3726 222; Fax: + 36 1 3726 342
udvardyl@hoya.kee.hu

Ailanthus altissima (Mill.) Swingle is native to China in the lower Yangtze and Korea, but its synanthropic area in China is much wider. Its global distribution has begun in the 1740's (HU 1979). The first data of tree of heaven in Hungary are were published by Bartosságh (1841, 1843), who planted young trees on his own estate in Villány to the southern foot of Szársomlyó hill of Nagyharsány, which were damaged by frost. Soó Jávorka (1951) indicates it already as an established plant on the Great Hungarian Plain (Alföld). For its widespread in Hungary old and more recent suggestions of its planting "with many uses" (Danszky 1964) could contribute to a great extent. Soó Kárpáti (1968), Simon (1992) and Bartha Mátyás (1995) indicates its frequent naturalisation, and that it is planted in plantations on the Great Plain. Invasion of Ailanthus altissima in Hungary is conspicuous in the following instances: in the Aggtelek National Park on one of the natural habitats of Onosma tornense JÁV., which is a strictly protected, endemic plant of limestone rock grasslands of the Northern Carpathians, and which has been taken on the list of Red Data Book of Europe; in the Villányi Mountains on Szársomlyó, on the locus classicus of Colchicum hungaricum Janka, a strictly protected preglacial relic, endemic in the Balkans; on the Balaton Highlands near Salföld on a protected rock-land area with junipers and acidophilous grasslands; in Fót-Somlyó Protected Area in steppe grasslands; in Budapest in the Sas-hegy Nature Conservation Area in warm, south facing slopes of limestone rock grasslands.
In the above mentioned areas tree of heaven has penetrated into natural habitats (in more cases first ones were planted there by man) and changes the composition of the local vegetation, endangering the survival of numerous rare, protected species. Among artificial environments Ailanthus altissima appears subspontaneously in botanical gardens and in almost all parks in Budapest due to insufficient horticultural work. Tree of heaven on the other hand is a characteristic plant of disturbed urban and country habitats, i.e. in the city in gaps between walls and the pavement and other artificial objects, in industrial areas, by railways, and by country ways.

References
Bartha D. Mátyás CS. (1995): Erdei fa és cserjefajok elõfordulása Magyarországon. Sopron. 223 pp.
Bartosságh J. (1841): Beobachtungen und Erfahrungen über den Götterbaum  (Ailanthus glandulosa L.) Ofen, Gyurián u. Bagó. III, 47 pp.
Bartosságh J. (1843): Folytatólagos értesítés a‚ bálványfa (Ailanthus glandulosa, Götterbaum) terjedése körül. - Magyar Gazda 3: 298ˆ300.
(abstract)

László Udvardy and Márta Bényei-Himmer

University of Horticulture and Food Industry Department of Botany Hˆ1118 Budapest, Ménesi út 44.
Hungary
Phone: + 36 1 3726 222; Fax: + 36 1 3726 342
udvardyl@hoya.kee.hu

Hedera helix L., native to Hungary, is native to all over Europe, and is an ornamental plant since the beginning of formation of garden cultivation. Primarily its handsome, more lobed, white veined and variegated leaf types are popular. Besides the native ivy, Hedera hibernica (Kirchner) Bean is planted since already 1815, which had been offered in the catalogues as Irish or English ivy primarily for its quick growth and handsome, big leaves. The origin of this tetraploid species (2n:96) is still unclear, by Koch (1869) "it was born in England in cultivation, but is originated from Ireland". In the Hungarian trade it has been surely existed in the 1870's, and was planted mainly in cemeteries, city gardens and parks.
In the late some years the weed effect of Irish ivy appears, especially in arboreta, collection gardens and their surroundings. In natural, and more or less disturbed seminatural vegetation, in flood areas and islands it appears, where H. helix is not native. Because the young leaves of H. hibernica are similar to that of H. helix, especially its form, named f. sagittifolia, it is easy to confuse with that. Distinguishing the two species can be made by the followings: Leaves of vegetative shoots of H. hibernica are about one and a half times as big as that of H. helix, broad, three lobed, the central lobe is broad, ending in a domy tip. Their surface is glossy, the venation is bright green, inconspicuous. Leaves of the generative shoot are broad ovate, the inflorescence axis is short (3-5 cm), its special and characteristic feature is a single flower under the main umbel. H. hibernica brings generative shoots often in the ground level, and becoming spontaneously a bush. Berries on short, 1 cm peduncles, become fertile only in the terminal umbels of the inflorescence. In spite of H. helix - where in most cases only 2-3 ovules become fertile - mostly 5 seeds develop, which can contribute to its propagation of greater extent. The fruity umbels of Irish ivy form brilliant, glaucous, deep blue balls, which mature in February, from which time the fruits of it are spread by birds (endozoochoria). Due to our observations about habitat preference of Irish ivy the followings can be stated: it appears in places of relatively even water supply, deep shade, slightly protected from frosts, e. g. under shrub-groups, hedges, and as a gap-inhabitant in the base of house walls, leaks of concrete, asphalt, stone and other artificial objects. Within the classification of adventive plants it belongs to the group of cultivation escapers (ergasiophygophyta).

References
Bényeiné-Himmer, M. (1994): A borostyán mint õshonos és kultúrnövény
Magyarországon. (Ivy as a native and cultivated plant in Hungary). - Candidate dissertation, University of Horticulture and Food Industry, Budapest (manuscript).
Lammermayr, L. (1930): Der gattung Hedera L. - Pflanzenareale, Reihe 64-69.

Lucia Viegi

Department of Botanical Sciences, Via L. Ghini, 5- 56126 Pisa
Italy
Tel. ++39 +50 561795; Fax  ++39 +50 551345
lviegi@vet.unipi.it

Since 1974 the Italian alien Flora has been revised and discussed from floristic, ecological and distributional points of view. More recently (Viegi, 1992/93) the attention has been focused on the invasive alien species in Sardinia. As previously reported (Viegi, 1998) the presence of aliens and in particular of invasive ones, in Italy is noticeable. An investigation on the type of their reproductive structures and on their mode of dispersal is extremely interesting in order to evaluate possible removal strategies.
In this paper we study from the statistical point of view: sex expression, life forms, blooming period, type of pollination, types of fruits and fruit dispersal and vegetative reproduction of alien invasive species in Italy. We used as data sources mainly Floras by Pignatti, (1982), Viegi (1974, 1992/93), Viegi et al. (1974, 1981, 1990, 1991, 1995).
A total of 210 species were analysed, which are distinguished in: escaped from cultivation, naturalised, casual and doubtful. The most represented families are Asteraceae, Amaranthaceae, Poaceae, Fabaceae and Brassicaceae. As regards sex expression, hermaphrodite are over 80 %, monoecious and dioecious 2%. T life form result the most represented (over 50%), followed by H (17%) and G (9%); the others are in low percentages (7%-2%). July, August and September are the months when a higher percentage of species blooms. Entomophilous species are more than the anemophilous ones. There are more dry fruits than fleshy ones, which are only 5%. Passive dispersal of seeds is predominant, followed by anemochorous and zoochorus. The most frequent type of dry fruits is the capsule in dicots and the caryopsis in the mono; the most frequent fleshy fruit is the berry.
The results are discussed on the base of a quantitative/qualitative comparison with data reported for native species (i.e. in general in Italy (Pignatti and Pignatti, 1990-91), in Mediterranean region (Pacini and Franchi, 1984), Apuan Alps (Viegi and Pacini, 1998)) and with data from other countries (Brock et al., 1997).

References
Brock J.H., Wade M., Pysek P., Green D. (Eds.), 1997 - Plant invasions: studies from North America and Europe. 223 pp. London.
Pacini E. and Franchi G.G., 1984 - Reproduction in Mediterranean plants. Webbia, 38: 93-103.
Pignatti S., 1982 - Flora d'Italia. Edagricole, Bologna.
Pignatti F. and Pignatti S., 1990-91. - Dati quantitativi delle flore italiane da Bertoloni ad oggi con particolare riguardo al problema dei corotipi. Mem. Accad. Lunigian. di Scienze 'G. Capellini', 60-61: 249-258.
Viegi L., 1974 - Definizione e nomenclatura delle specie esotiche della flora italiana. Inform. Bot. Ital., 6, 136-137.
Viegi L., Cela Renzoni G., Garbari F., 1974 - Flora esotica d'Italia. Lavori Società Italiana di Biogeografia, n.s., 4, 125-220.
Viegi L., Cela Renzoni G., 1981 - Flora esotica d'Italia: le specie presenti in Toscana. C.N.R., AQ/1/132, 99pp..
Viegi L., Cela Renzoni G., D'Eugenio M.L., Rizzo A.M., 1990 - Flora esotica d'Italia: le specie presenti in Abruzzo e in Molise (revisione bibliografica e d'erbario). Arch. Bot. Ital., 66, 1-128.
Viegi L., D'Eugenio M.L., Rizzo A.M., 1991 - Piante ornamentali ed infestanti, erbacee od arbustive, di origine americana in Europa. In "1492-1992- Animali e piante dall'America all'Europa, Genova, Sagep.
Viegi L., 1992/93 - Contributo alla conoscenza della biologia delle infestanti delle colture della Sardegna nordoccidentale. I. Censimento delle specie esotiche della Sardegna. Boll. Soc. Sarda Sci. Nat., 29: 131-234.
Viegi L., D'Eugenio M.L., Rizzo A.M., Cela Renzoni G., 1995 - Aggiornamento della flora esotica díItalia: le specie presenti in Emilia-Romagna, Marche, Umbria. Giorn. Bot. Ital., 129 (2): 187.
Viegi L., 1998 - Observations sur la distribution d'entities exotiques (en particulier adventices et envahissantes) dans differentes regions d'Italie. Biocosme Mèsogèen, Nice, 15 (1): 69-88.
Viegi & Pacini, 1998 - Statistical analysis of some reproductive features of Apuan Flora. Proceed. IX Colloque Optima, Paris, 11-17 mai 1998. Bocconea (in press).

The present work was financially supported by a grant of Italian M.U.R.S.T.

Montserrat Vilà and Isabel Gimeno

Centre de Recerca Ecològica i Aplicacions Forestals. Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Catalonia
Spain
Tel: 93-5811987; Fax: 93-5811312
vila@cc.uab.es

There is a great effort in determining factors controlling establishment of exotic species in natural communities in order to assess which communities are more prone to invasion. The lack of natural enemies has been claimed as one of the main causes of the invasion success of alien plants. However, few studies have investigated the role seed predation in the spatial patterns and population dynamics of alien plants.
Prickly-pear cacti (Opuntia spp) were introduced from Central America to Europe by the Spanish conquerors between the end of the 15th century and the beginning of the 16th century. Prickly-pear cacti have been used for fruit consumption, livestock foraging, fencing, the production of a red dye which is obtained from a cochineal insect host, and as ornamental. However, economic and land use changes have driven the naturalization of the species in natural areas of the Mediterranean region and now Opuntia can be considered a weed. Although, vegetative spread by cladodes is important for its population persistence, seedling establishment is also important for the extension of the geographical range and the initial establishment in new sites.
We studied post-dispersal seed predation of Opuntia maxima and O. stricta in old olive orchards, pine woodlands and shrublands in Cap de Creus (northeastern Spain). In average 2/3 of seeds from fruits were predated. Cage exclusion experiments demonstrated that fruits and seeds were mainly consumed by small rodents. Seeds placed in olive orchards were less predated than the ones placed in pine woodlands and shrublands. In olive orchards seed predation was lower under olive trees than beneath adult Opuntia plants and clearings. Our results demonstrate that seed-predation is acting differently among communities and also within a community matching differences in establishment patterns of Opuntia seedlings among and within communities.

Ewald Weber and Daniel Gut

Swiss Federal Research Station of Fruit-Growing, Viticulture and Horticulture, CH-8820 Wädenswil
Switzerland
Phone: ++1 783 63 25; Fax: ++1 780 63 41
ewald.weber@faw.admin.ch

Land use change and the continuing introduction of new species may lead to new weed problems in European countries. In order to evaluate species that might become future plant invaders in arable fields of Switzerland, we conducted an European wide survey of weed species by sending questionnaires to weed scientists. Recipients were asked to list species that are spreading and cause problems in agroecosystems, and to rate these according to the degree of weediness. We identified those species that currently are not present in Switzerland or do not pose weed problems (potential new weeds). In total, 299 weed species were reported from European countries.
Among these, 73 species (24%) could be identified as potential new weeds.
Source regions of these species were mainly southern and eAstern parts of Europe. We ranked the species according to number of countries and habitats in which they occur in order to find species that are likely to become weed problems in Switzerland. The five species with the highest rankings were Abutilon theophrasti, Iva xanthifolia, Phalaris paradoxa, Avena sterilis and Matricaria perforata. Weed scores as given by recipients varied considerably and showed no relationship to distribution of the species.
 

Mark Williamson

Department of Biology, University of York - York YO10 5DD
United Kingdom
mw1@york.ac.uk

In the 4th International symposium (4th ICEIAP), I discussed the measurement of the impact of invasive plants. Here I want to extend that both to explaining the impacts, explaining the measurements, by relating them statistically to other measures and also to see to what extent explanation can be expanded to prediction. There are many people who think that invasions can be predicted climatically, and in other ways. Examples will be given of such predictions and examined critically. Good explanations of the success of invaders have often depended on very detailed biology of the species. There are at least ten reasons why even good explanations may lead to unsatisfactory predictions. The question then is, under what circumstances will it be possible to get useful predictions ? The examples in the paper will mostly be drawn from the distribution of British and Australian plants, but other impacts will also be considered.

G. Wozniak

University of Silesia; Faculty of Biology and Environmental Protection; Department of Geobotany and Nature Protection; 40-032 Katowice; ul. Jagiellonska 28
Poland
wozniak@us.edu.pl

One of the results of industrial activity is the existence of expansive areas being post-industrial west lands, without plant cover and its surface is covered by specific substratum (e.g. coal dust) On the background of the surrounding vegetation these areas consists a kind of habitat islands. It has been stated that plant expansion on such places is carried out in different ways. By means of transect system it has been investigated which species and how fast do they manage to establish on those habitats. New data for species observed by such method have been obtained. The investigation on primary succession on coal-mine sedimentation pools has been carried out for seven years on 137 objects (few hectares each).
The presented paper contains:

* the list of kenophyte (new comers) species observed on (all 137) objects;
* ecological characteristics of stated species;
* the frequency of the plants occurrence (on particular objects);
* the participation of kenophytes among species which establish first on the bare coal dust substratum;
* the participation of the kenophytes in the floras of particular objects;
* the role of the described species in course of quality and quantity changes in plant composition during the plant cover development;
* the kenophyte participation in plant communities of different internal structure complicity dependent on the development stage of vegetation.
 

M. Zajac and A. Zajac

Institute if Botany, Jagiellonian University, 31-501 Cracow, Kopernika 27, Poland
zajacm@ib.uj.edu.pl

Studies of the horizontal distribution of kenophytes (meaning neophytes according to Thellung) in the Polish Carpathians (Zajac M, Zajac A., 1998) and the data on their vertical ranges, communities where they occur, native range of distribution and the manner of their introduction into the area concerned, permit and underpins some hypotheses about their success in penetration.
The proximity of the native range and often the mountain characteristics of a taxon in its homeland can be identified as two of the most important success factors. The species once cultivated by humans and later returned to the wild have a decisive advantage over those species which incidentally become kenophytes. This is probably associated with the fact that a large number of diaspores with the appropriate ecotopic variability reach the colonised area. Another factor ensuring the success is the ability to penetrate extrazonal communities (e.g. associated with river valleys). Also important is the method of dissemination (anemochores prevailing greatly among them).
The altitudinal spectra show, however, that in their vertical distribution, with only some exceptions (even the species which have characteristics of mountain plants in their homelands) they mostly occupy the habitats within the foreland and lower coniferous forest zones. In higher locations, the climate and the competition in natural (or primary) communities are the principal limiting factors. In principle, only a major intervention by humans (erecting major technical structures or buildings) can enable them to penetrate higher locations.
The issue of the factors enabling kenophytes to penetrate the mountains is becoming increasingly important in Europe in connection with the ever intensifying management of the last enclaves of natural and primary vegetation.

Franco Zavagno (1) and Giovanni D'Auria (2)

(1) Il canneto s.s. - via Varese 12, Bareggio (MI)
(2) Via Bagnara 58, Cremona
Italy
canneto@cnn.it

In the Po Valley (Lombardia, Italy) about 130 relevés of different vegetation typologies with the presence of Amorpha fruticosa L. have been carried out, the analysis of which has contributed to define its ecology and its dynamic and synecologic role.
This species is favourite in human-disturbed environments. In particular, it constitutes an important species in secondary successions, when human activity diminishes (e.g. grown-wild poplar-groves, sides of the quarry-lakes, abandoned fields). In these cases, if the soil moisture is suitable (Amorpha fruticosa is an hygrophilous species), it enters early and becomes the most important pioneer shrub species, quickly forming a close and exclusive covering.
Nevertheless Amorpha fruticosa is also found in more natural plant communities, such as Large-sedge swamps and Reed swamps where, however, it is often transitory, probably because the water drift is too strong. Furthermore it is distributed in Cornus sanguinea and Sambucus nigra communities, and, seldom, in Grey Willow scrubs. The subsequent evolution seems leading to the riparian forest (Populetalia Br.-Bl. 1931) or, more rarely, to the mesophilous deciduous forest (Fagetalia sylvaticae Pawl. 1928).
Under favourable conditions the scrub phase is rather permanent, probably thanks to the high competitivity of the species.
As regards synecology the Amorpha fruticosa scrub includes particularly characteristic species belonging to Artemisietea vulgaris Lohm., Prsg. et Tx. 1950 (i.e. Convolvuletalia sepium Tx. 1950) and Phragmitetea Tx. et Prsg. 1942, and, subordinately, others belonging to Querco-Fagetea Br.-Bl. et Vlieg. 1937 (i.e. Prunetalia Tx. 1952).

Key words: Amorpha fruticosa, Bastard Indigo, Lombardy, Po Valley, shrubs

Erika S. Zavaleta

Dept. of Biological Sciences, Stanford University, Stanford, CA 94025
U.S.A.
Tel. 650/324-4694
erika@jasper.stanford.edu

Recent interest in the valuation of ecosystem services has provided tools for assessing the market and non-market monetary impacts of invasive species. This study provides an economic evaluation of the effects of the invasive Tamarix species complex on societally-valued ecosystem services in its naturalized range. Tamarix, a woody plant introduced in the 19th century from Eurasia, has invaded most riparian areas of the arid and semiarid western United States. In its naturalized range, Tamarix has at least three major impacts on natural systems. First, it transpires more water than native riparian vegetation, which in a region marked by drought and water scarcity has significant economic implications. Second, it increases sedimentation in river channels, leading to increases in the frequency and severity of floods. Third, Tamarix provides poor habitat for native fauna, including birds, mammals, reptiles, and phytophagous insects. With growing public interest in parks, preserves, birdwatching, and wildlife conservation, these impacts on native fauna have economic implications as well. Conservative economic estimates of each of these impacts indicate that over the next 55 years, the costs of Tamarix to the western United States will total $6-16 billion. The cost of eradicating the invader and restoring native riparian ecosystems is significantly lower ($3-5 billion). These findings are robust to variations in discount rate and to the exclusion of non-market values from the analysis. Furthermore, changing climate, rising atmospheric CO2, and growing human populations will likely increase the costs of tolerating Tamarix. The economic argument for eradication will therefore likely grow stronger in the future, illustrating the importance of acting soon in the case of Tamarix and of examining the effects of other harmful invasives before global change has the opportunity to increase their impacts on society.