Just released Conserving the plants of eastern South Island limestone, Nga tipu o te pakeho, by Peter Heenan and Geoffrey Rogers is a free to download publication on the conservation of specialised limestone flora of the eastern South Island (Marlborough, Canterbury and Otago), also available as a stunning wee A5 field book. The first 50 pages outline the geology, evolution/history of these calcicole (limestone loving) plants, the challenges they face and the threats which are bringing many to the brink of extinction. This is followed by 74 fact sheets (2 pages each) for each of the specialist limestone plants known from the eastern South Island. 27 of these plants are yet to be described and formally named, for now they have intriguing tagnames like Craspedia “Awahokomo” (a woollyhead) and Myosotis “Waipara” (a forget-me-not). A nice touch is the inclusion of a couple of paintings by Nelson artist and former South Marlborough Threatened Plant Botanist, Cathy Jones, one being Limestone violet and Limestone angelica instantly recognisable for the few in the know of this special place.
Here are a few sample pages of personal favourites, click on the photo to see it at a readable scale.
Click this link to download Nga tipu o to pakeho and then ‘Download full-text pdf’. For a hard copy contact firstname.lastname@example.org , there’s a cost for P&P of $5.50 within NZ
Nga tipu o te pakeho, was preceded in 2018 by a relatively technical document written for the Department of Conservation, also by Geoff and Peter along with Shannel Courtney, providing an overview of the situation for limestone plants at a national level. ‘Science for Conservation 331. The calcicolous vascular flora of New Zealand Life forms, taxonomy, biogeography and conservation status‘. Which is available for download from the Dept’s publications page here, and for the fact conscious, I’ve included the abstract.
This report describes the life forms, taxonomic status, geological biogeography and conservation status of 152 calcicolous taxa in New Zealand, 91 (60%) of which have been formally named. Of the remaining 61 unnamed taxa, 26 are raised in this study with supporting voucher specimens. This is the first endeavour to describe the calcicolous vascular flora of New Zealand which, at 5.6% of the estimated total New Zealand vascular flora, is substantially greater than previously thought. Most calcicoles (91%) are confined to the South Island, with only 13 taxa occurring in the North Island, and 95% of the calcicoles are endemic to regionally-confined geological units, with a richness bias towards units located in West Nelson, Marlborough and Canterbury. In addition, 73% have total habitat areas of < ̄10 ha, likely as a result of adaptation to persistent, isolated, differentiated terrains that provided non-forest habitat throughout the numerous climatic cycles of the Pleistocene. In total, 71 (47%) of the calcicolous taxa are ranked as Data Deficient or Threatened (cf. 14% of the entire flora), 43 (29%) of which are ranked as Nationally Critical. However, 33 (46%) currently receive no form of conservation management. Together, our measures of taxonomic resolution and extinction risk argue for this being a particularly under recognised and threatened flora and ecosystem.
On a personal level, I’ve had the good fortune to work with some of these plants and in these outstanding landscapes, which I would hope everyone can appreciate for their sheer awesomeness.
Here’s a few pics and observations from working with ‘the plants belonging to limestone’ in the last 20 years.
Surveying the Chalk Range
for the Chalk Range cress (Pachycladon fasciarum, p160)
Dave Barker and I, carried a roll of weldmesh onto the crest of the range to install some experimental cages.
Because the numerous goats
are probably the biggest, immediate, threat facing this plant at the current time.
Ben More is a prominent (1200m) hill cloaked in native tussock
that crests onto an escarpment
home to the forget-me-not (Myosotis arnoldii, p150),
amongst other cool plants
Down in Isolation Creek
The stunning canyon is decorated by the equally stunning Mathew’s harebell (Wahlenbergia mathewsii, p206) along with a host of other calcicolous plants.
Altitude, scale and isolation do a lot to protect the flora of places like Isolation Creek but the bulk of the special species are found in small, fragmented landscapes such as the Tengawai escarpment.
Here the future for the plants is gloomy at best. Farming pressures have seen the covering shrubby vegetation sprayed off and the escarpment fertilised and oversown. Whether deliberate or accidental doesn’t really matter, the deed is done, and the calcicoles over much of the escarpment are dead and gone displaced by a thin scurf of ryegrass, clover and weeds, it will take radical changes in management to turn the tide on habitat loss here. On at least one section goats are farmed, they in turn camp on the escarpment resulting in additional nutrients that filter down the crevices boosting the weeds that dislocate the unique calcicoles like the endemic Tengawai buttercup (Ranunculus callianthus, p178)
Limestone geranium (Geranium socolatum, p140)
and the endemic Manahune gentian (Gentianella calcis ssp. manahune, p134) not pictured in this post.
The Tengawai story is repeated to some degree at most of the sites where limestone outcrops across both islands. Economic pressures, ignorance of the values present in farmed sites and the general encroachment of exotic plants, with grazing by exotic animals, combine to create a unique flora under pressure of extinction.