The New Zealand Plant Conservation Network

What needs to happen to prevent the extinction of Bartlett's rata (http://www.nzpcn.org.nz/flora_details.aspx?ID=24) and to improve its conservation status from Nationally Critical to Recovering? And are any of those things being done by anyone?

Rata moehau or Bartlett's rata (Metrosideros bartlettii) is in a serious situation because the largest population, which occurs on a waahi tapu within a privately owned block of land is currently judged in terminal decline because of a rampant possum population. In April 1991 Tony Silbery, Tim Shaw, Mike Avis and I discovered the species there - it had hitherto been only known from two sites in western Te Paki (Kohuronaki and Radar Bush), and between April 1991 and April 1992 Mike, Tim, Gillian Crowcroft and I discovered 24 trees within the waahi tapu. All of these trees occur in the tops of other trees - such as kohekohe (Dysoxylum spectabile), puriri (Vitex lucens) and taraire (Beilschmedia tarairi) - sampling seed from them is virtually impossible without the aid of a helicopter or skilled tree climber, and as far as we know there is no material from this site in cultivation.
The other trees in western Te Paki - (7) occur on public conservation land and they are managed for possums

As recently as 2008 the Department of Conservation (DOC) became aware that the largest population, that on private land was being eliminated by a virtually uncontrolled possum population. As this population is beyond our ability to directly manage we have had to work in with iwi, who at the time were engaged in complex treaty settlement claims.
To further complicate matters we in New Zealand are expecting the arrival of myrtle rust (Uredo rangelii) which is now rampant in Australia and has naturally reached New Caledonia. Its impact on the Myrtaceae worldwide has been serious, and some Australian genera are believed likely to go extinct. In New Zealand we are uncertain what it will do, though it is likely to most severely impact on our endemic Lophomyrtus and Neomyrtus - it does damage Metrosideros but to what degree it will affect rata moehau remains unknown.

For that reason, right now MPI and the NZ Seed Bank are preferentially working on collecting seed of New Zealand Myrtaceae, and also planning for what will happen when this rust arrives here - because based on past experience with other rusts it will.
Central to that work is to ensure we obtain as many of the naturally occurring rata moehau as we can. Critical to that is our knowledge of what genetic diversity is left in the wild and in cultivation. Drummond et al. (2000) under took an AFLP DNA finger printing analysis of the genetic diversity of the then extant wild population of rata moehau - despite claims they discovered 19 new trees (they didn't) their work did show that most of the genetic diversity resides within the privately owned rata moehau population.

Rata moehau is self incompatible, and their work showed that those western Te Paki trees are more closely related to each other than those in the east, and that most seed produced is the result of selfing due to lack of natural , effective population vectors and the close sibling relationships between trees. Therefore seed taken from western populations will do little in the long-term to secure the species. It is imperative that plants from the eastern population are bought into cultivation - not only to ensure we save the species genetic diversity but also as a preventive when myrtle rust arrives.
Recently DOC has been told that cultivated material from the eastern Te Paki population does exist - but this is disputed, and the only way to resolve that issue is undertake DNA finger printing. Sadly we cannot simply test cultivated plants and match that against the data presented by Drummond et al. (2000) - we have to do it all over again.

To that end DOC and Landcare Research along with iwi - Ngati Kuri, Te Aupouri and the Muriwhenua Trust Inc. will be systematically sampling all known wild plants left for seed (seed banking) tissue for DNA sequencing and also looking for the scarce endemic liverwort Frullania wairua - known only from rata moehau. This work will start in March - April 2015 and finish in June 2015. We will also be sampling as many cultivated plants as we can - to resolve once and for all where they come from.
John - this will not prevent the extinction of the species on the privately managed site in eastern Te Paki. That will require the eradication of possums, and that will require agreement from iwi and private land holders. That issue has been raised by DOC but it is up to the landowners to decide what they wish to do.

These are issues which I know you know all about because you worked for DOC and you also have visited many of the rata moehau populations, and spoken with landowners, iwi and DOC staff about these issues.
If you in your new role have the ability to find funds for possum control then I am sure Ngati Kuri, Te Aupouri and DOC partnerships people would be more than interested in hearing from you.

Reference:

Drummond, R.S.; Keeling, D.J.; Richardson, T.E.; Gardner, R.C.; Wright S.D. 2000: Genetic analysis and conservation of 31 surviving individuals of a rare New Zealand tree Metrosideros bartlettii (Myrtaceae). Molecular Ecology 9(8): 1149-1157.

The authors assert they found 19 new trees - they didn't - they followed the verbal and written directions and maps supplied to Shane Wright by DOC staff.

Finally - putative hybrids that I collected involving M. bartlettii and M. excelsa or M. robusta, and reported as valid in recently literature, remain unsubstantiated. The putative M. bartlettii x M. robusta were shown to be M. bartlettii on the basis of DNA sequencing, whilst the M. bartlettii x M. excelsa as not sampled by Drummond et al. (2000). Further study is needed to determine whether hybridism (introgression) also threatens this species.

So now you (and others have the facts) - you asked what needs to be done?

Obviously possum control (eradication) - if the possums were gone this species (and many others as threatened or more so e.g., invertebrates) would naturally recover in eastern Te Paki and we would have better opportunities to restore genetic variability to the western populations and also to restore genetically variable populations to other secure sites in Te Paki. There is nothing complicated about the solution but getting there is the issue....