Title: Prosopis spp.

Scientific Name:

Prosopis spp. (including P. alba, P. flexuosa, P. glandulosa, P. juliflora, P. pallida, and P. velutina)

Common Names:

mesquite, Quilpie mesquite, honey mesquite and velvet mesquite (P. velutina).



Mesquite

Habitat: The semi-arid subtropics and tropics, mostly in better watered valley bottoms, gullies and intermittently flowing streams beds, occurring on a range of sands and sandy loams, usually at altitudes below 1500 m. Plants spread readily from these water courses to the adjacent higher ground, under the influence of grazing and favourable summer rains, and are often found along roadsides near areas of habituation. In Australia all forms of mesquite tend to grow on heavier (more clayey) soils which support open woodland or grassland (Parsons and Cuthbertson, 1992).

Distribution:

Present Distribution - Australia (source: ALA)




Invasiveness Assessment

ESTABLISHMENT


1. Germination requirements? ""Seeds germinate in summer after periods of very warm temperatures and rain." Requires natural seasonal disturbance. (Parsons and Cuthbertson, 2001)

2. Establishment requirements? "Requires a period of very warm temperatures. "Temperature appears to be more important than available water." Optimal germination temperature is 29°C."Honey mesquite seeds must be covered with a small amount of soil or dung for seedlings to establish. Seeds that germinate on the soil surface usually die." Requires specific conditions to germinate. (Parsons and Cuthbertson, 200; Steinberg, 2001)

3. How much disturbance is required? Commonly found in intermittently flowing streambeds from where they spread into adjacent areas depending upon favourable rainfall. "...often found along roadsides near areas of habitation." Occur mostly in highly disturbed areas (riverbeds, watercourses) in open areas. "In Australia, all forms of mesquite tend to grow on heavier soils which support open woodland or grassland." (Parsons and Cuthbertson, 2001)

GROWTH / COMPETITIVE


4. Life form? Shrubs to small trees, nominally deciduous. Part of the Fabaceae family, mesquites are leguminous. (Parsons and Cuthbertson, 2001)

5. Allelopathic properties? Extracts from the ground litter (mesquite pods and leaves) have an allelopathic effect on germinating seeds of other plant species. (Parsons and Cuthbertson, 2001)

6. Tolerates herb pressure? Grazing animals eats pods, but spines may discourage animals from browsing on the leaves and stems. "Livestock do not consume the foliage to any great extent. Foliage consumption is high only during drought years." Grazing does not affect the survival or reproductive ability of the tree. (Parsons and Cuthbertson, 200; Steinberg, 2001)

7. Normal growth rate? Shoot growth is slow (compared to root growth). Maximum growth rate may be less than other species of similar life form. (Parsons and Cuthbertson, 2001)

8. Stress tolerance to frost, drought, w/logg, sal. etc? In the U.S., mesquite is found in areas where average minimum temperature is -5°C and the frost-free growing season is longer than 200 days. The deep root system (15 to 20 metres) would ensure most trees survive periods of drought. "Fire mortality is usually low in honey mesquite. Following most range fires, honey mesquite is top-killed and then resprouts." Survives fire. Information on tolerance to salt or waterlogging is not available. (Steinberg, 2001; Parsons and Cuthbertson, 1992)

REPRODUCTION


9. Reproductive system? "Deciduous shrubs or small trees, reproducing by seed and suckers." Reproduces sexually and vegetatively.(Parsons and Cuthbertson, 1992. p. 108)

10. Number of propagules produced? “"...honey mesquite produces pods in... abundance." Trees produce more than 100 pods per season, and in a Californian study, each pod contained an average of 12 seeds. Produces between 1,000 and 2,000 seeds. (Steinberg, 2001)

11. Propagule longevity? "Little is known about honey mesquite seed banks [or] seed longevity in the field." "Mesquite seeds have a relatively short seed longevity when the pods are kept on the soil surface. Within 12 months, less than 20% of the seeds are still viable in good seed production years while <0.1% remain viable in some years." Seeds survive less than 5 years". (Owens et al., n.d)

12. Reproductive period? "Maximum ages that plants attain is unclear. Near Amarillo, Texas, the maximum age of plants within a stand of multi-stemmed honey mesquites ranged from 40 to 110 years. On the Rio Grande Plains of Texas, Archer found that 89% to 93% of honey mesquite plants were less than 100 years old, and the maximum age of plants sampled was 172 to 217 years." Plants are very long-lived (more than 10 years). (Steinberg, 2001)

13. Time to reproductive maturity? "Young plants do not flower until they are 2 to 3 years old and from 1 to 1.5 metres high." (Parsons and Cuthbertson, 2001)

DISPERSAL


14. Number of mechanisms? Prosopis spp. spread is mostly by seed. Both livestock and native animals consume the seed pods, and many of the seeds pass through the digestive system intact. The pods and seeds float, so they may be dispersed long distances in floodwater. Propagules spread by water and animals. (Parsons and Cuthbertson, 2001)

15. How far do they disperse? Floodwaters are likely to spread seed much greater than one kilometre, animals to a lesser extent. (Parsons and Cuthbertson, 2001)


Impact Assessment

RECREATION


1. Restrict human access? In Western Australia, "because of their thicket-forming characteristics, they...limit ingress to watering points." Dense patches would create an impediment to accessing waterways. (Parsons and Cuthbertson, 2001)

2. Reduce tourism? Dense patches limiting access to waterways may affect some recreational activities.

3. Injurious to people? No toxic principles, however, the stems are "armed with paired stipular spines just above each leaf axil." A deciduous shrub, the spines are present all year. (Parsons and Cuthbertson, 2001)

4. Damage to cultural sites? Root system not documented as being vigorous; not known to cause structural damage. The plant can grow as a many stemmed shrub 1 to 3 metres high, large single-stemmed tree 6 to 15 metres high, or branching almost from the base and forming dense thickets 5 to 8 metres high. Dense patches would be obvious and create a moderate negative visual effect. (Parsons and Cuthbertson, 2001)

ABIOTIC


5. Impact flow? Terrestrial species (Parsons and Cuthbertson, 2001)

6. Impact water quality? Terrestrial species (Parsons and Cuthbertson, 2001)

7. Increase soil erosion? The plant was grown in, "Pakistan and India...to combat erosion." However, due to the plant removing all grass cover under the canopy, "...erosion problems are exacerbated." Moderate probability of large scale soil movement. (Parsons and Cuthbertson, 2001)

8. Reduce biomass? "In Australia, all forms of mesquite tend to grow on heavier soils which support open-woodland or grassland. They spread rapidly [which] usually results in the complete loss of grass cover." Would increase biomass. (Parsons and Cuthbertson, 2001; Muyt, 2001 p. 70)

9. Change fire regime? With increased biomass in grassland situations, dense infestations may result in a moderate change to both the frequency and intensity of fire risk.

COMMUNITY HABITAT


10(a) Impact on composition of high value EVC? EVC=Plains grassy woodland (E); CMA=North Central; Bioreg=Victorian Riverina; VH CLIMATE potential. Mesquites tend to grow in open-woodland or grassland situations where they spread rapidly. The mass of surface roots usually results in the complete loss of grass cover. Major impact on grasses and displacement of mid storey species. (Parsons and Cuthbertson, 2001)

10(b) Impact on medium value EVC? EVC=Box Ironbark forest (D); CMA=North Central; Bioreg=Goldfields; M CLIMATE potential. Impact similar to above, however, medium CLIMATE potential only, limiting population size.

10(c) Impact on low value EVC? Appears unlikely to occur in any low value EVC in Victoria.

11. Impact on structure? In open-woodland or grassland situations, "competition from the mass of their surface roots usually results in the complete loss of grass cover. The allelopathic effects from ground litter (mesquite pods and leaves) extracts, prevents the seeds of other species germinating." Major effect on the lower and mid strata. (Parsons and Cuthbertson, 2001)

12. Effect on threatened flora?

FAUNA


13. Effect on threatened fauna?

14. Effect on non-threatened fauna? "Prosopis spp. are aggressive invaders and competitors. Because of their thicket-forming characteristics, they reduce available grazing area and limit ingress to watering points." Dense infestations would reduce habitat of native fauna. (Parsons and Cuthbertson, 2001)

15. Benefits fauna? "Pods are sweet, fairly nutritious, and relished by livestock, but heavy consumption can cause digestive problems." Possible limited food source for native fauna. (CDFA)

16. Injurious to fauna? Although the stems are armed with spines, there is no evidence to indicate they injure animals. Potential exists. (Parsons and Cuthbertson, 2001)

PEST ANIMAL


17. Food source to pests? "Pods are eaten and then dispersed by domestic and wild animals." Potential food source to pest animals such as rabbits. (USDA)

18. Provides harbor? Where plant grows as a thicket, it may provide harbor for pest bird species.

AGRICULTURE


19. Impact yield? "Prosopis spp. are aggressive invaders and competitors. Because of their thicket-forming characteristics, they reduce available grazing area and limit ingress to watering points. In some situations competition from the roots results in the complete loss of grass cover." Reduces carrying capacity. (Parsons and Cuthbertson, 2001)

20. Impact quality? Not a weed of cropping. Not known to affect quality of yield.

21. Affect land values? Reproduces sexually and vegetatively. Dense infestations can be difficult to eliminate due to the longevity of the seed. In southwestern United States, "Many species of mesquite respond positively to overgrazing and grasslands are subsequently converted to mesquite brushlands. Conversion back is very difficult and temporary with reduced grazing pressure." Dense infestation likely to have a major impact on land value. (CDFA)

22. Change land use? As above. "American experience convincingly demonstrates that the best means of obtaining control of larger colonies is by integrating available techniques, including mechanical, cultural, chemical and biological." This may lead to extended non-availability of grazing land. (Parsons and Cuthbertson, 2001)

23. Increase harvest costs? In Western Australia infestations, "hinder mustering." Increased time to harvest animals. (Parsons and Cuthbertson, 2001)

24. Disease host/vector? None evident.




Feedback

Do you have additional information about this plant that will improve the quality of the assessment? If so, we would value your contribution.


Assessment ratings originally made by the Victorian Department of Primary Industries.
The entry of this assessment was made possible through the generous support of The Weed's Network.






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Categories: :wra:p, :wra:inv1, :wra:invmh, :wra:inv2, :wra:invml, :wra:inv3, :wra:inv4, :wra:inv5, :wra:inv6, :wra:inv7, :wra:inv8, :wra:inv9, :wra:invh, :wra:inv10, :wra:inv11, :wra:invl, :wra:inv12, :wra:inv13, :wra:inv14, :wra:inv15, :wra:imp1, :wra:impml, :wra:imp2, :wra:imp3, :wra:imph, :wra:imp4, :wra:imp5, :wra:impl, :wra:imp6, :wra:imp7, :wra:imp8, :wra:imp9, :wra:impmh, :wra:imp10a, :wra:imp10b, :wra:imp10c, :wra:imp11, :wra:imp12, :wra:impm, :wra:imp13, :wra:imp14, :wra:imp15, :wra:imp16, :wra:imp17, :wra:imp18, :wra:imp19, :wra:imp20, :wra:imp21, :wra:imp22, :wra:imp23, :wra:imp24
Date: 13 May 2009; 3:38:51 PM AEST

Author Name: David Low
Author ID: adminDavid