ARTICLE : 2002 EVENING MEETING REPORTS

 20 May 2002 :   Julia Stace – Extreme weeding on Raoul Island

Julia gave us a fascinating and beautifully illustrated talk about her four months working as a volunteer for DOC on weed eradication on Raoul Island, about 920 km northeast of North Cape.

Raoul Island, the largest in the Kermadec archipelago, is about 10 km long, up to 7 km across, and covers 2938 ha.   The island is a complex volcano which has erupted three times since its discovery by the French in 1793, the last time in 1964.   The highest point is Moumoukai, 516 m.   The island is steep with dry ravines and a dense forest.

It is a Nature Reserve under the Reserves Act 1977, and the coastal waters are a Marine Reserve.   Raoul contains all of the approximately 20 species of plants endemic to the Kermadecs, but introductions of alien plants and animals have resulted in drastic modifications to the island’s ecosystem.   Goats which were present from at least 1836 have been eliminated, and this winter, DOC has attempted to eliminate Norway rats, kiore, and cats.

Over the last 150 years, introduced plants have flourished in the subtropical climate and encroached on the native bush.

Among the pest plants the team were destroying were Mysore thorn, purple and yellow guava, grape, black passionfruit, peach, Brazilian buttercup, African olive, and madiera vine.   They combed the ravines, systematically removing the invaders, and recording each of the sites cleared of them.   It is painstaking, rugged work, in steep, dark ravines, in hot weather or heavy rain.

After years of work by DOC and the former Department of Lands and Survey, Julia said that great progress had been made in destroying pest plants.   However, weed seeds may continue to germinate for the next 80 years.   With goats eliminated, and if successful, rats and cats all killed by the recent poisoning operations, Raoul will be able to start the long path to ecological restoration and become a haven for seabirds.

Chris Horne

Julia Stace Raoul-bound again!

PS. We congratulate Julia who has been chosen to be one of the party of five who will spend a year on Raoul Island in the Kermadec Archipelago.   The group comprises the leader, a mechanic, and three rangers.   Julia and the other rangers will continue the intensive weed eradication programme.   We look forward to reports from the island for publication in future Newsletters.

Editor

 10 June 2002 : Philip Simpson:   Protecting nature on private land in Marlborough

The presentation was concerned with the place, the project and the people.

The ecology of the region is distinctive, diverse and damaged.   A distinctive range and pattern of plant species and communities has been generated location of the South Marlborough region.   Central in New Zealand (Lat. 41.30-42) the region has many nationwide native species (mahoe, tree fuchsia, rimu) but also many near their southern limit or limited to the Cook Strait area (tawa, taupata, tree hebe).   Located at the top of the South Island the region draws on a wide range of geological, topographical and climatic landscapes, with the clear, sunny skies an important factor.   The eastern location means a dry climate overall, especially in summer, but exposure to the south also brings cold winter weather.

A complex core of Jurassic sandstone, associated in places with uplifted blocks of Paleocene limestone, is surrounded by a discontinuous skirt of soft Miocene – Pliocene mudstone.   Active faulting has created a landscape with many bluffs, gorges, scarps, riverbeds and gravel coastlines.   On these sites the distinctive drought-tolerant Marlborough plants have evolved (for instance, pink brooms, rock daisy and lilac hebe).   A second feature is the rarity of otherwise common forest species (such as nikau, miro, rangiora, kawakawa) in the dry zone between the more mesic Marlborough sounds and Kaikoura coast.   The rocky habitats have often remained protected from human impact (fire, grazing, wild animals and weeds), which has otherwise been substantial across the region.

Rock daisy.   Photo: Geoff Walls.

Except for the most rugged areas, the land has been farmed, and the natural vegetation has been fragmented.   Hence, a survey of the remaining natural areas on private land is a priority, given the unusual range of species characteristic of the region.   The survey is being undertaken only on properties with full owner support.   Each property is surveyed and significant sites identified and described in a way intended to be meaningful to the owner.   A copy of each report is provided to the landowner by Marlbourgh District Council, and the survey team solicits responses from the owners, in particular concerning their interest in implementing any recommendations, with council assistance.   A property management plan has been suggested for some areas as a tool to protect landscape while maintaining farm production.   Simply informing the landowners about the natural features of their land is regarded as the first important step.   There is a high level of appreciation of the natural values of the properties by the owners and a desire to see them protected.   However, a general concern by the owners is a possible loss of economic and management opportunities if significant sites were to be identified within the District Plan.

Landscape complexity, endemic species, range limits and rarity induced by climate or human impact, together make surveying the region an exciting undertaking.   Among the highlights, mention can be made of the joy of finding a specimen of otherwise common species, such as kowhai high on a dry, open hillside, the fascination of species on limestone bluffs (like Wahlenbergia matthewsii), observing the ecological significance of all native species of Muehlenbeckia, including the rare M. debilis, identifying the northern coastal limit of rock daisy, and finding the single surviving nikau in the extreme NE South Island.   The co-operation between landowners, Council and the surveyors also makes the exercise a rewarding experience for all.   There is a real prospect for significant conservation.   This largely rests on sufficient resources being available for fencing, alternative water supplies, the restoration of species and places, and wild animal and weed control.   As well, continuing discussion with landowners is a key to the success of the project.

Philip Simpson

 15 July 2002:   Graeme Jane: Some aspects of Bay of Plenty vegetation

Graeme’s comprehensive and well illustrated talk whetted our appetites for our 2-12 January 2003 field trip, when he will take us on field trips to the Kaimai Range, Waimangu, Rotorua, Minginui in the Urewera, Matata and the Whakatane / Ohope area.

He began by defining the Bay of Plenty as the coastal area and hinterland parts of the Coromandel, Northern Volcanic Plateau, and Whakatane Ecological Regions.   It ranges from Karangahake Gorge to Ohiwa, and inland to the fringes of the Urewera.

Graeme told us how the flora of the region had been determined by geology, landscape, climate, altitude, disturbance, volcanism, climate, people and wild animals.   Rocks range from greywacke in the Urewera, to volcanic rocks in the Kaimai / Coromandel, and Rotorua areas, with a heavy overlay of ash, mostly from the Rotorua centre.   The Northern Volcanic Plateau features a sloping plateau descending from about 900m at Rotorua caldera to the coast, and is cut by very young, deeply entrenched streams and rivers with flat, smooth, rocky bottoms.   The plateau is deeply overlain by pumice ash which produces quick draining, highly fertile soils.   The Urewera has a greywacke basement with an overlay of Rotorua or Taupo pumice or clayey ash towards East Cape, probably from White Island.   The result is fertile soils on ridges, and low fertility stony greywacke on steep slopes.   Areas within 20 km of the 1886 Tarawera eruption have a deep ash like a scoria, and a rugged terrain.

The long shore tropical current, coupled with lots of sand derived from the pumice and siliceous ash from the volcanoes leads to shallow bays with sandy shores, and barrier islands such as Matakana, and peninsulas such as Maunganui / Papamoa Beach.   Most of the formerly extensive coastal wetlands and swamps have gone, or have been heavily modified.

The area marks the southern limit of warm currents, and this, with the volcanic activity further south, creates a demarcation point for species distributions.   The Bay also often marks the limits of both warm tropical cyclones and the cold southerly snow storms.

Although it may seem an insignificant fact, the maximum altitude of 1000m at Mt Te Aroha, combined with the climate, means that alpine species are largely absent from the area, except for a gentian at its northern limit, because there are no open tops.   All the beeches, except hard beech, reach their northern limits in the area, as the result of a wedging out of species.

There are four main vegetation zones:
• lowland pohutukawa forest, mostly highly modified
• northern mid-altitude kauri forest
• southern mid-altitude tawa forest
• high altitude beech forest – pure red beech or silver beech

In the thermal areas, tropical species have established, yielding significant southern records for species, especially ferns and Psilotum.

Disturbance by continuing volcanic activity, e.g. the massive Taupo eruption in about 100AD, has had a major influence in creating the dense podocarp forests in the Urewera at Minginui.   It largely displaced the beeches from that area – a few pockets remain.

Tropical cyclones periodically cause wind throw, often over large areas, such as in the Urewera in 1984, and lead to extensive landslides in the shallow, impervious soils in the Kaimai Range.

Europeans soon began to clear the forests and drain the swamps for pasture, and later for exotic forestry.   Trees were felled for timber for housing, butter boxes etc.   Much of the logging was by tramways.   These provide some of the better tracks in the Kaimai Range, where logging continued until the 1970s.   Gold mining, which peaked in the 1920s, also resulted in loss of forests.   Goats have had severe impacts on the forests.   Hunting began in 1948 and intensified in the 1970s until they were virtually exterminated.   Deer were liberated near Te Aroha about 1917, and in the Urewera about the same time – here their impact remains severe.   Possums have spread slowly.   In the Urewera, their impact has been insidious, often removing kamahi from tawa / kamahi forest, but in the Kaimai Range the wetter climate seems to have kept numbers relatively low.

Recently, 50,000 ha in the northern Urewera (Waimana) has been set up as a mainland island, and is achieving impressive results.   At Kaharoa, a private initiative has had a local impact.

The lowlands are largely cleared, and apart from waterworks areas within 1km of the coast, are almost devoid of forest or shrubland.   The shore wetlands have only been protected for the last decade or so.   Consequently short manuka shrubland may be the only woody native vegetation.   Tauranga City Council is active in restoration of the coastal estuaries, and providing recreational access.

Chris Horne

 19 August 2002: Dr Brian Molloy –   Tony Druce, field botanist extraordinaire

When Tony Druce died on 15 March 1999, Wellington Botanical Society and the New Zealand botanical community at large lost an esteemed friend and colleague.   Also, as Ian Atkinson, perhaps his closest friend and colleague said, “we lost one of the greatest contributors to the botanical exploration and discovery of New Zealand this country has seen”.   However, while we lost the man and the botanist, we inherited from him a rich botanical legacy of inestimable value; most noteworthy being his immense collection of carefully annotated specimens in the Allan Herbarium (CHR) at Lincoln; his collection of live plants at Percy Scenic Reserve, Petone; his checklists of plants from numerous localities throughout New Zealand; and his draft national list of native vascular plants.   To these we could also add the numerous fresh specimens he supplied to Audrey Eagle and now illustrated in her Trees and Shrubs of New Zealand.   Few if any taxonomic treatments of our native flowering plants and ferns can be written today without reference to the specimens or entities provided by Tony Druce.

North Island edelweiss.   Photo: Jeremy Rolfe.

I first came into contact with Tony Druce, who was ten years my senior, when I transferred from the Department of Agriculture to Botany Division, DSIR, in 1970.   From time to time when he visited Lincoln, or I visited Wellington, we would spend a few hours in the field together sharing information on plants of mutual interest such as orchids, conifers, mistletoes, grasses, coprosmas, and others.   At that time I was associated with Peel Forest Park in South Canterbury and was especially interested in the unnamed edelweiss there.   After some discussion with Tony, he suggested that we visit some of his haunts in the North Island and in Nelson / Marlborough to examine other edelweiss species and populations.   And so began an annual fruitful field excursion to different parts of the country which continued until 1994.   At times we travelled and explored together; on other occasions we were joined by colleagues and friends eager to profit from Tony’s unique mastery of our native flora.   Some field visits were centred on particular species; others were designed to compile species lists for particular localities.   Some sites, because of their botanical interest, were visited several times.   All the while we added to his herbarium and live plant collections, his checklists and national list of species, and kept Audrey Eagle busy and happy with fresh material to illustrate.

It is not possible here to recount all the field visits and discoveries we experienced together over about 15 years.   What I propose to do now is to share with you my experiences in the field with Tony Druce during our edelweiss survey; visits to special places such as Tapuaeoenuku, Mt Somers and the Havelock River; our mutual interest in special habitats such as certain wetlands, limestone and other rock types; with a Coprosma and Melicytus species or two thrown in for good measure.

Tony Druce was first and foremost a gifted field botanist of extraordinary ability.   It has been a great privilege to have known and worked with him.   We are unlikely to see his equal in the future.

Brian Molloy

 16 September 2002 :   Dr Linley Jesson – Evolution of mirror-image flowers

Enantiostyly is a plant sexual polymorphism in which the female sex organs are deflected either to the left or right, resulting in mirrorimage flowers.   Although enantiostyly occurs in at least a dozen unrelated familes of flowering plants, and has been known for over a century, its adaptive significance remains enigmatic.

In this talk, I described the distribution of mirror-image flowers in the flowering plants, and outlined experiments to eludicate the genetic control of the phenomenon.   Plants which are left- or right-handed are controlled by a simple, system where right-deflected styles are dominant to left deflected styles.   I concluded by suggesting that mirror image flowers is a phenomenon which functions to promote the precision of cross-pollen transfer.   The multiple origins of mirror-image flowers among angiosperm families provides a striking example of a floral stragety that evolves many times to promote pollen dispersal in bee-pollinated plants.

Linley Jesson, Lecturer in Plant Ecology, Victoria University of Wellington.

 18 November 2002 :   Steve Urlich – Monitoring terrestrial habitats in Wellington Conservancy, a strategy for 2003 – 2012¹

Terrestrial habitat monitoring is a key area for the Department of Conservation (DOC).   Monitoring enables DOC to detect changes in health and functioning of ecosystems, as well as enabling regular reporting on their condition.   Monitoring also enables DOC to determine the effectiveness of conservation management, and to provide confidence in DOC’s ability to achieve its strategic objectives.

A strategy has been prepared that describes the vision of ecological monitoring in Wellington Conservancy.   It also describes five ecological research themes:
• Effects of invasive species
• Disturbance ecology
• Fragmentation ecology
• Threatened plant communities
• Habitats sustaining threatened biota

These themes are structured around better understanding processes that maintain indigenous species diversity, ecosystem stability, structure, and functioning, and will be used to guide management at important sites within the Conservancy.

A ten-year monitoring programme that integrates outcome, result and surveillance monitoring² techniques has been devised, which also identifies monitoring priorities.   The combination of monitoring approaches in key ecosystems will provide data for managers, leading to an increased capacity to measure conservation achievement, as well as more efficient and effective use of resources.

The strategy includes a review of habitat monitoring in Wellington Conservancy that demonstrates the value of historical investment in monitoring done from the 1950s to the 1980s.   Vast amounts of data were collected on the condition of large tracts of forest, subalpine and alpine vegetation.   Since the 1990s, emphasis has switched from monitoring ungulate impacts to focusing more on possum outcome and result monitoring, and result monitoring of weed control programmes.   To achieve a more robust picture of ecological management, the strategy recommends a balance of surveillance monitoring of ungulate impacts and weed invasions, combined with possum and weed outcome and result monitoring.

Finally, the strategy acknowledges the need for working with iwi, conservation groups, regional and district councils, and enthusiastic members of the community, to increase our ecological knowledge.

¹ This talk, presented to the meeting by Steve Urlich, was based on the strategy jointly prepared for DOC by Steve Urlich and Phil Brady.   The strategy will be published early in the new year.

² Outcome monitoring is the measurement of change in the native species condition after control.   Result monitoring is the measurement of change in the pest affecting native species after control.   Surveillance monitoring is measurement of long-term changes in managed and unmanaged areas.