Literature review: Impact of Chilean needle grass ... - Weeds Australia

(Honaine et al. 2006). The flechillar (Nassella-Piptochaetium) community in this area has especially high biodiversity and is
ecologically significant as a faunal refuge (Honaine et al. 2009).
To the north in Argentina, in the department of Gualeguay in the south of Entre Rios Province, N. neesiana occurred in
undulating treeless plains covered in grasses (Marco 1950), an area classed as Mesopotamic Pampa and characterised by a more
subtropical climate (annual rainfall c. 900-1200 mm), and a network of water courses lined with gallery forest (Soriano et al.
1992). Stipoids generally are of lesser importance in this formation than in the southern pampas, but N. neesiana was one of the
dominants along with N. tenuissima, Eragrostis cilianensis (All.) Janchen. and species of Axonopus, Paspalum, Digitaria,
Schizachyrium and Bothriochloa (Soriano et al. 1992).
The Flooding Pampa, an extremely flat coastal plain covering 9000 km 2 (Perelman et al. 2001) in eastern Buenos Aires province
that includes the Laprida and Río Salada basins and extends in tongues into the interior (Soriano et al. 1992), has some dominant
grasses in common with Rolling Pampa but N. neesiana is not a major species (Soriano et al. 1992). Nevertheless it occurs
through most of the region across its latitudinal range (c. 35-38°S) and with a frequency of ≥20% (in 25 m 2 samples) in 8 of the
11 Flooding Pampa grassland community types identified by Perelman et al. (2001), reaching a frequency of 87% in one
community. In the Flooding Pampa it has been classified in a three-species floristic group with Jarava plumosa (Spreng.) S.W.L.
Jacobs and J. Everett (as Stipa papposa) and Bothriochloa laguroides (Perelman et al. 2001).
N. neesiana is of minor importance in most of the Inland Pampa, a drier, more open grassland, lacking a river and stream
network, found to the west and south-west of Rolling Pampa. However it is one of a number of grasses of lesser importance in a
community dominated by Poa ligularis, Nassella tenuissima, N. trichotoma, N. filiculmis (Delile) Barkworth and Panicum
urvilleanum Kunth on the border between the provinces of Buenos Aires and La Pampa (Soriano et al. 1992). Its minor
importance in the Caldenal, an ecotonal region between the Humid Pampa and the Monte desert, is reflective of the regional
climate with an annual rainfall of 300-400 mm concentrated from spring to autumn, annual potential evaporation of 800 mm and
cooler temperatures than the pampas (Fernández et al. 2009).
Little native grassland remains in Uruguay, and protected areas of natural grassland landscape are non existent (Cosse et al.
2009). In the Juan Jackson region of south-western Uruguay N. neesiana was considered to be the third most important grass in
“virgin and regenerated” caespitose grasslands on granitic soils, after Piptochaetium stipoides (Trin. and Rupr.) Hackel ex
Arech. and P. montevidense (Spreng.) Parodi (Gallinal Heber et al. 1946). Soriano et al. (1992) considered it to be the most
frequent grass in the Southern Campos, a formation extending over most of southern part of the country, along with other
Nassella spp., Paspalum spp., Poa spp. and other grasses. On deep fertile soils the natural vegetation was probably dominated by
Nassella charruana. In the Atlantic coastal south-eastern plain Stipeae are less abundant, being displaced by an abundance of
subtropical genera, and are dominant only in relatively restricted “upland prairies” located on hills and knolls with shallow soils,
dry in the summer (Iriarte 2006).
In Brazil N.neesiana is most common in ‘cleared and treed fields’ (rough translation of Longhi-Wagner and Zanin 1998). It is
not an important component of the natural vegetation of the Northern Campos of northern Uruguay and the campos of the
southern Brazilian State of Rio Grande du Sol, which have fewer Stipeae and more numerous representatives of Paniceae and
Andropogoneae (Soriano et al. 1992). N. neesiana was not found by Overbeck and Pfadenhauer (2007) in surveys on Morro
Santana, near Porto Alegre in Rio Grande do Sul, near the eastern edge of Brazilian campos, an area with rainfall exceeding
1200 mm per annum and no dry season, but Overbeck et al. (2007 p. 106) list it (as Stipa setigera C. Presl) as a subtropical area
“characteristic” species of grasslands in the southern Rio Grande do Sul of Brazil, along with N. megapotamia, N. nutans (Hack.)
Barkworth and N. philippii (Steud.) Barkworth. The northern boundary of the Pampean province of southern Brazil is at about
30°S (Overbeck and Pfadenhauer 2007).
On the Juan Fernández Islands of Chile it is found on rocky slopes near the sea, in dry or humid gorges, rocky cliffs, on and
between rocks and in open places (translation from Baeza et al. 2007).
In south-western Europe most exotic Stipeae occur on disturbed land or higly modified areas and have failed so far to occupy
more natural areas, with the exception, to date, of N. neesiana, which “penetrates into natural, protected areas ... and behaves like
an aggressive invader” in the Canary Islands (Verloove 2005) e.g. in the Garajonay National Park, Anaga Rural Park and Osorio
Reserve (Sanz-Elorza et al. 2005). Since the mid 1960s it gradually spread along roads and through gaps and sparse vegetation
on the island of Tenerife in nitrogen enriched environments (Martín Osorio et al. 2000). The larger Tenerife infestations occur on
hard, basaltic substrates (Martín Osorio et al. 2000). South-western European N. neesiana “inhabits a wide range of usually
anthropogenic biotopes varying from road-verges, abandoned vineyards, urban parks ... more or less ruderalized pastures, etc.”
but also occupying rocky slopes in river valleys in France and Italy (Verloove 2005 p. 108). In Catalonia (Spain) small
populations have been found on path margins and in abandoned vineyards (Font et al. 2001).
In New Zealand it occurs mainly in pastures and on roadsides (Edgar and Connor 2000) in dry, low-fertility, open habitats
(Bourdôt and Ryde 1986) on various soil types, but not normally in fertile pastures where there is good competition from other
plants (Bourdôt and Ryde 1986, Auckland Regional Council 2002). It occurs on “rolling hills and flats” at Waipawa (Bourdôt
and Ryde 1987a), and often occurs on “steep inaccessible eroded land” (Bourdôt 1988). It invades unimproved pastures,
infesting two of seven paddocks dominated by native tussock grasses in the Lake Grassmere area (Bourdôt and Hurrell 1989a).
Its invasiveness in New Zealand sheep pastures was attributed by Bourdôt and Hurrell (1989a) to adaptations enabling survival
in semi-arid, poorly fertile environments, rather that high competitive ability.
The little information available on the native vegetation formations invaded by N. neesiana in areas of its exotic range outside
Australia is summarised in Table 3.
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