provenance & genetic quality

A number of issues relating to the source and genetic make-up of native seed have a large impact on ultimate success of restoration projects. 

Provenance

The provenance phenomenon refers to the fact that for any given species, there is often local genetic adaptation to local environmental conditions. Over the past twenty years this has sometimes resulted in much confusion about suitable sources of native seed, and often a very strict limitation being placed upon the geographic distance from the project site permissible for native seed collection.

It is now generally accepted that genetic vigour and diversity of the source population is far more important than geographic distance in determining suitability of native seed batches. These factors are discussed below, and for more information you can also click the following link to the Florabank website that discusses the latest scientific research in relation to provenance and genetic issues: http://www.florabank.org.au/default.asp?V_DOC_ID=1018&V_LANG_ID=0

The Florabank page also contains a link to an article by the CSIRO's Dr. Linda Broadhurst and colleagues that discusses the latest research in the field or you can access the article directly through the following link:

http://www3.interscience.wiley.com/cgi-bin/fulltext/121397345/PDFSTART

The CSIRO press release that accompanied the publishing of the paper can be found at:

http//:www.csiro.au/news/Seed-Sourcing.html

Despite this updated reasearch and thinking in relation to provenance, in some situations the use of local seed is preferred, and Diversity Native Seeds can assist in the sourcing of such material for specific projects.

Matching seed genetics to site conditions

More important than geographic distance of the seed source from the planting site and applicable in more situations is the principle of using seed that may not be strictly local but that is properly adapted to the site. In other words it is important that the genetics of the native seed stock adequately match the environmental conditions of the project site. For example plantings can fail when seed sourced from coastal populations with no frost tolerance are used in inland locations where heavy frosts occur. We assist customers in accessing native seed that originates from suitable locations by analysing conditions at the project location and matching those with available batches of seed. We are able to do this through accurate records of seed origins. Full provenance details and details of number of parent plants are also available. Where large differences in habitat exist within the distribution of a species, we try to stock representative provenances representing that variation. For example we stock both climbing (dry sclerophyll forest) and shrubby (grassy woodland) Hardenbergia violacea provenances. 

Diverse genetic base

Seed collected from small populations or from only one or a few individuals in large populations results in progeny with a narrow genetic base i.e. inbred stock. This often results in poor performance of plantings. Diversity Native Seeds ensures that seed is collected from numerous individual parent trees to maximise genetic diversity and vigour. Where this is not possible we mix batches of seed from different locations to maximise diversity. In keeping with the recent research cited above, for many projects we believe that mixing suitable batches of seed is an appropriate strategy not only to ensure vigour of the stock in the short term, but also to maximise the genetic variation available to the population, allowing it to adapt to factors such as climate change.

Matching native seed genetics to specific functional or productive requirements

For many purposes such as farm forestry it is important that plant genetics not only suit the environmental conditions at the site but also provide additional benefits. An example is growth rate and straight form in timber plantings. Where possible we will endeavour to source selections and provenances with required characteristics.

Seed orchard design at Sarana

-maximising genetic diversity and vigour

Wherever possible the original seed stock used in the establishment of the orchards was derived from known wild stands. Seed was derived through our own collections, from the CSIRO Tree Seed Centre and from commercial seed companies and nurseries. In almost all cases we made sure that original stock was derived from the maximum number of parent plants, usually between 50-100. Seed wascollected from across as wide a geographical distance within the population as possible in order to minimise multiple collections of closely related plants.

The populations represented in the seed orchards derived from this seed generally consist of between 100-600 plants in the case of trees and 200-4000 in the case of shrubs.

Wherever possible plants are juxtaposed in multiple rows rather than single rows in order to maximise pollen dispersal among numerous mother plants.

-avoidance of hybridisation

Much thought has gone into the design of the plantations to minimise risk of hybridisation among related plants. The level of quarantine placed on plants depends on their general promiscuity based on published research and general horticultural and field observations. For example it is well known that hybridisation is widespread within some groups at the species level (Eucalyptus, Callistemon), and less common among others (Acacia, Pultenea). For the Eucalypts, species within the same section of a given subgenus are considered to be at risk of hybridisation and are therefore isolated from eachother. For more information try the following link:

Eucalyptus hybridisation research summary