Table 7. Water regime required for recruitment and regeneration of all species. In some instances rainfall will provide sufficient water for regeneration. Species Precondition (flowering stimulus/fruiting stimulus) Flood Follow-up flood (years) Depth of flood seedling establishment Flood duration (weeks) Eucalyptus camaldulensis subsp. camaldulensis Water 24–36 mths prior to seed fall; flowering flood induced in stressed trees; above av. Rain for bud set Recession Spring/early summer (or sufficient rainfall); artificial watering to extend effect For lower Murray summer germination- follow-up (or sufficient rainfall) 20–50 cm (soil moisture 4–6 Eucalyptus camaldulensis subsp. acuta Unknown Unknown Unknown Unknown Unknown Eucalyptus largiflorens Aseasonal induced flowering May–Oct): tree condition Recession spring-summer (or local rainfall) artificial flood not so useful. Summer germination (or local rainfall) 4 cm 4 weeks after 2 months of age Eucalyptus coolabah subsp. coolabah Flowering dependent on tree condition; intermittent rather than annual? Summer-late summer (but other factors important e.g. rainfall); episodic Unknown; not required? (c.f. Freudenberger 1998) Unknown Unknown Eucalyptus coolabah subsp. excerata Unknown Unknown Unknown Unknown Unknown Acacia stenophylla Not important Unknown; seed fall from spring to summer; artificial not so useful Unknown Unknown Unknown Duma florulenta Flowers in response to rain and flooding seed fall in response to aseasonal? 9–12 months after germination <15 cm 3 months
Table 8. The influence of other factors (population scale or landscape scale) on population sustainability. Salinity has an effect in relation to the ability of species to use groundwater, and use of surface water, and tolerance is given in previous table captions. Species Water Sources Seed storage/ viability Grazing, competition and adjacent land use Salinity Groundwater extraction Population constraints/viability Eucalyptus camaldulensis subsp. camaldulensis Groundwater Lateral bank recharge Rainfall Flooding Ponded surface water Serotiny in riparian systems (2 yrs). SB present in SW Vic. and SE SA. Dependent on tree condition: release following flood; ant modifies ant activity and removal of seed; seedlings directly grazed (more during drought) compete with and weeds Not generally salinity tolerant Unknown insects, birds and bats; seed supply density dependent?/hydrology dependent; little estab. under mature trees Density of stands 100s of years for ecosystem function Eucalyptus camaldulensis subsp. acuta Unknown Unknown Unknown Unknown Unknown Unknown Eucalyptus largiflorens Lack from all sources a constraint Serotiny in riparian systems (17mths–2 yrs); release uk; no SB; ant -granivory seedlings are grazed Salinity tolerant Big effect: increases reliance on flood and rain insects, birds and bats; Eucalyptus coolabah coolabah Unknown Potentially (i.e. dormancy can be induced), but not detected Seedlings are directly grazed; competition from grass not so important (amelioration); regen. is directly cleared Not generally salinity tolerant Likely to have big effect, usually floods not required because of groundwater Clearing of regenerating stands Eucalyptus coolabah subsp. excerata Unknown Unknown Unknown Unknown Unknown Unknown Acacia stenophylla Unknown Not buried, but dormant competition from occurs Salinity tolerant Unknown seed coat dormancy Duma florulenta Unknown No seed bank; ant Unknown Salinity tolerant Unknown Dioecious, heavily reliant on veg. reproduction -
Mature tree recovery from drought N/A 10.5 Table 16. Ecological water requirements for Acacia stenophylla: processes, drivers and stressors. Regeneration process Regeneration process Development of inflorescences (pollen and egg development) N/A Flowering Spring – Summer (Workshop 2015) Pollination Bees and other insects (Workshop 2105) Bud/seed development No differences in seed abundance in relation to flood frequency or duration (Murray 2014) Mature in spring to early summer (Murray 2014) Seed fall Does not form a long-lived soil seed bank (Holland et al. 2013) Seed dispersal Floating seeds, spread during floods (NSWGI&I) Germination Germination after nicking the seed coat with scapel: 1.1% at 20 C, 2.1% at 25 C (8hrs dark/16 hrs light) (D.Duval personal communication); Nick seed coat, surface sterilise, after ripening (2 months) 77 % (Sahito et al. 2013) C. 80% germination after treating with hot water (M.Henderson personal communication) Germination of one individual from the seed bank under damp conditions (M.Casanova personal communication) Occurs natural flooding (c.f. artificial watering) (Holland et al. 2013) Seedlings relatively common 2011 flood in a single germination event (Capon et al. 2012) Seedlings abundant and widespread (Capon and Balcombe 2015) Colonises cleared when water returns (Workshop 2015) Seedling establishment and growth Relatively once established? (Doody and Overton 2012) Can grow rapidly (Capon et al. 2012) Seedling density negatively related to time since inundation (i.e. greater time, fewer seedlings), and positively related to