Besom heath (Erica scoparia) – risk assessment notes

Originates from Europe, northern Africa, Macaronesia (CRC for Australian Weed Management 2007)

Domestication/Cultivation

1.01.  Species highly domesticated?

Yes

1.02.  Naturalised where grown?

Yes

1.03.  Weedy races?

None known

Climate and distribution

2.01. Suited to Australian climates? Yes, Tasmanian and Victorian modelling indicates “very high and high suitability to the eastern half of Tasmania (particularly NE) (Figures 1 and 2). Maximum score of 2 (Victorian Government 2008).

2.02. Quality of climate match data? Good – Tasmanian Climatch modelling and Victorian Government CLIMATE modelling. Maximum score of 2.

2.03. Broad climate suitability? Yes – Tasmanian and Victorian modelling indicates it is potentially suitable to large parts of southern Australia.

2.04. Native/Naturalised in regions with extended dry periods? Yes, in its native region (e.g. the Balearic Islands, Spain), the driest quarter of the year averages less than 50mm of rainfall (World Weather Online 2016).

2.05. History of repeated introductions outside natural range? Yes, eight references to the species being either naturalised or weed in the Global Compendium of Weeds (Randall 2012).

Weed elsewhere

3.01. Naturalised beyond native range Yes, naturalised in Tasmania (Groves 1997, Baker 2005), West Frisian Islands in the Netherlands (Nelson 2011, Randall 2012), on French subantarctic La Possession Island and Crozet Island (Frenot et al. 2001, Frenot et al. 2005) and also near Brest in Brittany, France (Nelson 2011).

3.02. Garden/amenity/disturbance weed? Yes, has spread to areas such as roadsides (disturbed) in Tasmania where it has naturalised (Baker 2005).

3.03. Weed of agriculture? Yes, recorded to cause serious growth problems in crop plants, “particularly with various grass species” (Rice 1984) due to its allelopathic properties. It will present a problem in unimproved pasture situations.

3.04. Environmental weed? Yes, recorded to invade grasslands (Bartolome et al 2005), likely to change habitats dramatically, potentially leading to extinctions (Victorian Government 2008a).

3.05. Congeneric weed? Yes, same genus as Spanish heath (E. lusitancia) and other weedy heath species.

Undesirable traits

4.01. Spines, thorns, burrs? No

4.02. Allelopathic? Yes, recorded to cause suppression of herbs (such as clover and grasses) and crop plants more generally (Ballester et al 1977, Rice 1984).

4.03. Parasitic? No

4.04. Unpalatable to grazing animals? Yes, not eaten at all by sheep and only to a very limited extent by goats (Bartolome et al 2005). ‘Erica scoparia, which is a prominent component of the heath vegetation, was completely avoided by both sheep and goats’ (Bartolome et al 1998).

4.05. Toxic to animals? No, no evidence of this.

4.06. Host to pests and pathogens? No, not known to be a host (Victorian Government 2008a)

4.07. Toxic to humans? No, no evidence of this.

4.08. Fire hazard? Yes, has evolved with fire (Ojeda et al 1996), and is likely to increase fire hazard.

4.09. Shade tolerant? Unknown, indications are that the species is shade intolerant (Arevalo and Fernandez-Palacios 2003), but it is not known whether this is the case for its entire life cycle.

4.10. Grows in infertile soils? Yes, in its places of origin it grows on infertile (e.g. sandstone derived) and/or acid soils (Ojeda et al 1996, Ojeda et al 2000, Bartolome et al 2005). Though there was no further specific evidence found for this species, capacity to grow in infertile soils is a consistent feature of members of the genus. ‘Ericas are capable of normal nutrition in average soils, but become mycotrophic in soils unfavourable to the direct absorption of nutrients – such as on a heather moor, where the soil is wholly humus …’ (Underhill 1971).

4.11. Climbing or smothering habit? No
4.12. Dense thickets? Yes, a ‘dominant sprouter’ after fire (Ojeda et al 1996) that can form ‘homogenous patches’ (Bartolome et al. 2005).

Plant Type

5.01. Aquatic No

5.02. Grass No

5.03. Nitrogen fixing woody plant? No

5.04. Geophyte? No

Reproduction

6.01. Reproductive failure in native habitat? No

6.02. Viable seed? Yes (Baker 2005)

6.03. Hybridised naturally? Unknown

6.04. Self-compatible or apomictic Unknown

6.05. Specialist pollinators? No evidence of this.

6.06. Reproduces by vegetative fragmentation? No evidence of this.

6.07. Minimum generative time? Unknown (Victorian Government 2008b)

Dispersal

7.01. Dispersed unintentionally? Yes, Seed ‘very fine and would be easily transported by water and on roadworks equipment’ (Baker 2005).

7.02. Dispersed intentionally by people Yes, ‘introduced [to Tasmania] as an ornamental’ (Groves 1997).

7.03. Produce contaminant? No evidence of this.

7.04. Wind dispersal? Yes, based on evidence of other Erica spp. such as E. cinerea (Soons and Bullock 2008) and E. baccans (Carr et al 1992).

7.05. Propagules buoyant? Yes, seed ‘very fine and would be easily transported by water and on roadworks equipment’ (Baker 2005).

7.06. Bird dispersed? No, ‘the small seed does not have structures for anemochorous (wind-borne) or zoochorous dispersion and their movement is mainly due to gravity’ (Bartolome et al 2005).

7.06. Dispersed by other animals? No, ‘the small seed does not have structures for anemochorous (wind-borne) or zoochorous dispersion and their movement is mainly due to gravity’ (Bartolome et al 2005).

7.07. Propagules survive passage through gut? Unknown

Persistence attributes

8.01. Prolific seed production (>2000/m sq.) Yes (Victorian Government 2008b).

8.02. Persistent seed bank? Unknown, though Cerabolini (2003) seems to suggest not.

8.03. Well controlled by herbicides? Unknown

8.04. Benefits from mutilation/cultivation? Yes - has ‘massive underground lignotubers’ (Ojeda et al 1996).

8.05. Natural enemies in Australia? Unknown

Figure 1. Climatch assessment for E. scoparia using source location map from Nelson (2011). Climatch conducted by Michael Noble on 10 February 2016.

Figure 2. Victorian CLIMATE assessment of potential suitability of E. scoparia. Suitability - red = very high suitability, yellow = high suitability, orange = medium suitability, green = likely suitability (DPI Vic 2008)

References

Arévalo J.R. and Fernández-Palacios J.M. (2003). Spatial patterns of trees and juveniles in a laurel forest of Tenerife, Canary Islands. Plant Ecology 165, 1-10.

Baker, M. (2005). Weed alerts. Tasweeds incorporating Spotter 28, pp. 10-11.

Ballester A., Albo J.M. and Vieitez E. (1977). The allelopathic potential of Erica scoparia L. Oecologia 30, pp. 55-61.

Bartolome, J., Franch, J., Plaixats, J. and Seligman, N.G. (1998). Diets selection by sheep and goats on Mediterranean heath-woodland range. Journal of Range Management 51 (4), pp. 383-391.

Bartolome J., Lopez, Z.G., Boncano M.J. and Plaixats J. (2005). Grassland colonization by Erica scoparia (L.) in the Montseny Biosphere Reserve (Spain) after land-use changes. Agriculture, Ecosystems and Environment 111, pp. 253-260.

Cerabolini B., Ceriani R.M., Caccianiga M., De Andreis R., Raimondi B. (2003). Seed size, shape and persistence in soil: a test on Italian flora from Alps to Mediterranean coasts. Seed Science Research 13, 75-85

CRC for Australian Weed Management (2007). Weed management guide; Managing weeds for biodiversity. Spanish heath (Erica lusitanica) and other Erica species.

Frenot, Y., Chown, C.L., Whinam, J., Selkirk, P.M., Convey, P., Skotnicki, M. and Bergstrom, D.M. (2005) Biological invasions in the Antarctic: extent, impacts and implications. Biological Review 80, pp. 45-72.

Frenot, Y., Gloaguen, J.C., Masse, L. and Lebouvier, M. (2001). Human activities, ecosystem disturbance and plant invasion in subantarctic Crozet, Kerguelen and Amsterdam Islands. Biological Conservation 101, pp. 33-50.

Groves, R.H. (1997). Recent incursions of weeds to Australia 1971-1995. CRC for Weed Management Systems, Glen Osmond, South Australia.

Nelson, E. C. (2011). Hardy heathers from the northern hemisphere – Calluna, Daboecia, Erica. Kew Publishing, Kew, UK.

Ojeda F., Arroyo J., and Maranon T. (2000). Ecological distribution of four co-occurring Mediterranean heath species. Ecography, 23, 148-159

Ojeda F., Maranon T. and Arroyo J. (1996). Postfire regeneration of a Mediterranean heathland in southern Spain. International Journal of Wildland Fire 6(4), pp. 191-198.

Randall, R.P. (2012). A global compendium of weeds (2nd Ed.). Department of Agriculture and Food, Western Australia. http://www.cabi.org/cabdirect/FullTextPDF/2013/20133109119.pdf (accessed 6 February 2015).

Rice, E.L. (1984). Allelopathy (2nd Ed.). Academic Press Inc., Orlando, Florida.

Soons, M.B. and Bullock, J.M. (2008). Non-random seed abscission, long-distance wind dispersal and plant migration rates. Journal of Ecology 96, pp. 581-590. URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2008.01370.x/abstract (accessed 25 March 2015).

Underhill T.L. (1971). Heaths and heathers; Calluna, Daboecia and Erica. David & Charles, Newton Abbot, United Kingdom.

Victorian Government (2008). Potential distribution of Erica scoparia in Victoria.

Victorian Government (2008a). Impact Assessment Record.

Victorian Government (2008b). Invasiveness Assessment Record.

World Weather Online (2016). Mjorca monthly climate average, Spain. http://www.worldweatheronline.com/majorca-weather-averages/islas-baleares/es.aspx (accessed 29 January 2016).