Most grasslands and woodlands support a fraction of the diversity they once held. Evidence suggests that many native grassland plant species that we now consider uncommon or rare were once both widespread and abundant. The decline of many species has been due to management practices associated with agriculture (fertilisation, cultivation, inappropriate grazing regimes) (McIntyre and Lavorel 2007, Dorrough 2010 and see documents under Further Reading). Native species have been particularly susceptible to increases in nutrient availability that have occurred as a result of agricultural practices (Dorrough, Scroggie and McIntyre 2011, McIntyre 2011). Populations of many native plant species are fragmented and isolated either owing to current or past management and changes in soil nutrient availability.
There is strong case for assisting the re-establishment of many of these now uncommon plant species (McIntyre 2011). Grasslands and woodlands suitable for re-establishment should be those with appropriate fire or grazing management and possessing low soil available nutrients (particularly available nitrogen and phosphorus).
In most cases the availability of seed is a key limiting resource. The soil seed bank of many of the native plant species of grasslands and grassy woodlands is short-lived or “transient” (Lunt 1997). This means that increasing plant diversity cannot often rely on seeds persisting in the soil.
There are some concerns regarding reintroduction of native plant species, particularly in relation to genetic pollution and subsequent impacts on local adaptations. However, most species of the grassy ecosystems of southern Australia appear to have had large continuous distributions with gene-flow across much of their range. It is arguable that species reintroductions will be a more important conservation strategy than maintaining genetic isolation and purity (McIntyre 2011). This is particularly important in the context of changing climate and gradual degradation of remaining habitats.
“Seed sourcing should concentrate less on local collection and more on capturing high quality and genetically diverse seed to maximise the adaptive potential of restoration efforts to current and future environmental change” (Broadhurst et al., 2008).
Linum marginale, native flax.
For a listing of grassland and woodland native seed available click here.
Broadhurst LM, Lowe A, Coates DJ, Cunningham SA, McDonald M, Vesk PA, Yates C (2008) Seed supply for broadscale restoration: maximizing evolutionary potential. Evolutionary Applications 1, 587-597.
Dorrough J (2010) The role of farm production systems in determining vegetation patterns and options for broad-scale conservation in temperate woodlands. In ‘Temperate Woodland Conservation and Management’. (Eds D Lindenmayer, A Bennett and R Hobbs) pp. 143-149. (CSIRO Publishing: Melbourne)
Dorrough J, McIntyre S, Scroggie MP (2011) Individual plant species responses to phosphorus and livestock grazing. Australian Journal of Botany 59, 670-681.
Lunt ID (1997) Germinable seed banks of anthropogenic native grasslands and grassy forest remnants in temperate south-eastern Australia. Plant Ecology 130, 21-24.
McIntyre S, Lavorel S (2007) A conceptual model of land use effects on the structure and function of herbaceous vegetation. Agriculture, Ecosystems & Environment 119, 11-21.
McIntyre S (2011) Ecological and anthropomorphic factors permitting low-risk assisted colonization in temperate grassy woodlands. . Biological Conservation 144, 1781-1789.