Nikau Research Articles

Forest seedling community response to understorey filtering by tree ferns

AbstractQuestionsLarge pteridophytes frequently co‐occur with conifers and angiosperms in the understorey of temperate broad‐leaved podocarp forests but interactions between them are poorly understood. We evaluated the impact of tree ferns on the regeneration niche of vascular woody species to determine whether tree ferns function as biotic filters and influence seedling occurrence. We asked the following questions: (i) do understorey tree ferns influence the woody seedling bank, and (ii) which potential mechanisms drive any such influence?LocationAuckland and Waikato regions, northern New Zealand.MethodsWe measured woody seedlings in 164 1‐m2 plots in northern New Zealand temperate broad‐leaved podocarp forest and used multivariate analyses and modelling to assess the relative contributions of abiotic and biotic effects on community composition and seedling abundance. We manipulated the environments beneath 160 tree fern individuals by removing fronds and/or macro‐litter in a balanced factorial design, and recorded the response of the seedling community over 1 year. We then assessed the relative influences of shading and litter depth on the seedling community response.ResultsDistance to the nearest tree fern was the best predictor of understorey seedling abundance; seedling abundance decreased beneath tree ferns. There was no strong evidence, however, that tree ferns influence seedling community composition; although the palm Rhopalostylis sapida, was consistently present away from tree fern micro‐sites. Removal of tree fern shading and macro‐litter both influenced the local seedling community; conifers responded positively, and most consistently to frond removal. Frond‐shading and deep litter reduced seedling species richness and seedling abundance.ConclusionsTree ferns influence the woody seedling bank in temperate broad‐leaved podocarp forest through increased shading and macro‐litter accumulation, both of which reduce the abundance of angiosperm and conifer seedlings. A tree fern‐dominated understorey is likely to reduce conifer establishment and may limit direct competition among woody plants by reducing densities and regeneration opportunities immediately beneath tree fern canopies.

City Profile: Wellington: Where Words Are Waiting

WORLDLIT.ORG 7 Like a beautiful, moody lover, Wellington doesn’t need to treat you kindly. Friends may sometimes wonder what you see in it, but when the city is good to you with its days of almost painful gorgeousness and clarity, you can forgive its bluster, its temper tantrums and cold shoulder. You may be clutching a lamppost, but at least you know you’re alive. – Kate Camp Wellington has been named “the coolest little capital of the world” and one of the top ten places to escape to. Affectionately known as Wellywood, New Zealand’s hipster capital is a city of film, sculpture, and creatives. Yet its literary credentials extend far beyond Tolkien. Katherine Mansfield casts a long shadow . In stories such as “Prelude,” “The Garden Party,” and “At the Bay.” In the restored Katherine Mansfield House and Garden where she spent her early years. In Woman of Words, the three-meter-high sculpture laser-cut with her words and phrases, depicting her striding along Lambton Quay. In her featured words, among those of twenty-three writers on the Wellington Writers Walk. From the landmark Wellington Central Library with its nikau palm columns, walk through Civic Square over the sculptural city to Sea Bridge. Scattered along the waterfront, often in the most unexpected places, lie concrete and metal inlaid quotations from some of New Zealand’s bestknown writers. Everywhere good words are waiting to be found. In independent bookstores with their helpful, knowledgeable staff: Unity, with its excellent range of intelligent New Zealand and international titles, its launches and readings; Kelburn’s Vic Books and Ekor with their superb coffee and food; Thorndon’s Millwood Gallery, which also sells artwork; Marsden in Karori; and the Children’s Bookshop in Kilbirnie. In secondhand bookstores: Arty Bees, with over one hundred thousand books; Pegasus, with its great readings; and The Ferret. But hide your books as you pass nearby Cuba Mall’s quirky bucket fountain. It’s designed to splash. The International Institute of Modern Letters organizes lunchtime Writers on Mondays at the national museum, Te Papa, and produces the online Best New Zealand Poems and literary journal Turbine. Wellington ’s many literary journals include two of the country’s best—Sport and the only one exclusively dedicated to reviewing the nation’s books, New Zealand Books. Bursting with literary activity, Wellington hosts the internationally star-studded biennial New Zealand Writers and Readers Week, the hugely popular LitCrawl, National Poetry Day events, poetry slams, and monthly poetry readings in the inner city and up the coast. What’s not to love in the world’s windiest city? Find a sheltered spot with a craft beer or one of the world’s best flat whites. Look out at the hills, the harbor, the sea. The city opens like a well-loved book. Alison Wong’s historical novel, As the Earth Turns Silver, is set in Wellington. To read a story and poem by Alison Wong, turn to page 28. Her Wellington reading list appears in the Takeaway at the end of this issue. photo : flickr . com / people / feefoxfotos Notebook city profile Wellington Where Words Are Waiting by Alison Wong ...

Looking Back for the Future: Local Knowledge and Palaeoecology Inform Biocultural Restoration of Coastal Ecosystems in New Zealand

We combine local knowledge of elders and environmental practitioners from two indigenous Māori communities and pollen evidence in soil cores from two islands and two mainland coastal sites to inform the planning of coastal ecosystem restoration initiatives in New Zealand. The Māori participants desired ecosystems that delivered cultural (e.g., support for identity), social (e.g., knowledge transfer), economic (e.g., agroecology) and environmental (e.g., biodiversity protection) outcomes to their communities. Pollen records identified three periods when vegetation was dominated by different taxa: (1) Pre-human (<AD c.1280) – forest dominated by native conifers, angiosperms and nīkau palm (Rhopalostylis sapida); (2) Māori settlement (AD c.1280–1770) – scrub and bracken fern (Pteridium esculentum); and (3) European settlement (post-1770) – Metrosideros excelsa forest with harakeke (Phormium sp.), raupō (Typha orientalis), grasses (Poaceae), exotic plantation conifers (Pinaceae), and agricultural weeds. A fourth, aspirational system that integrated human activities such as agriculture and horticulture with native forest was conceptualized. Our approach emphasizes the importance of placing humans within nature and the reciprocity of environmental and social well-being.

Neocypholaelaps novaehollandiae Evans (Acari: Ameroseiidae) rediscovered: experiments on its life history and behaviour

Members of Neocypholaelaps are pollenophagous and phoretic on a range of hosts. In New Zealand, Neocypholaelaps novaehollandiae Evans have been previously collected on native bellbirds and honeybees. The lack of information about this species triggered our interest in its life history and behaviour. We sampled mites from flowers of the nīkau palm (Rhopalostylis sapida), and subjected female mites (isolated in cells) to different diet treatments to determine the diet effects on mite survival. The survival of N. novaehollandiae was a maximum of 18 days in control to 33 days and 29 days on a diet of reed pollen and honey solution, respectively. We paired 20 males and females together in individual Eppendorf tubes and compared this with 20 single females in individual Eppendorf tubes. We demonstrated that unpaired females did not lay eggs but paired females oviposited in their cells, proving that mating is required for oviposition. We observed that six out of 10 samples contained only females (based on 2012 field surveys and preserved specimens in the New Zealand Arthropod Collection, NZAC). In samples with males, an incredibly female-biased sex ratio was found from both sources; 8.33% and 7.70% of males in two samples from the NZAC, and 2.42% and 13.10% of mites in two field samples. We observed that males display exceptional sexual dimorphism; in particular, the enlarged hind legs, which suggests male–male competition. We also report the first coleopteran host association of N. novaehollandiae with the endemic giraffe weevil (Lasiorynchus barbicornus). Further research is needed to understand the sexual dimorphism, extreme sex ratio and the genetic mating system of this species.

Niche partitioning in two coexisting species of Pahoroides (Araneae: Synotaxidae)

Spiders in the endemic New Zealand genus Pahoroides (Araneae: Synotaxidae) are all morphologically very similar. Two species, Pahoroides whangarei and Pahoroides confusa, coexist in Pukenui Forest near Whangarei, Northland, living in vegetation close to the ground. We tested the hypothesis that P. whangarei and P. confusa occupy distinct ecological niches defined more by conditions at the microhabitat level than at the macrohabitat level. Twenty random sites within Pukenui Forest, from which a range of macrohabitat and microhabitat variables were collected, were sampled by beating vegetation for Pahoroides spiders. Both species were distributed throughout the forest, and in many cases, were found at the same sites. However, neither the presence nor abundance of one Pahoroides species was associated with that of the other. Whereas macrohabitat variables such as aspect, litter cover and overall plant community composition were not associated with either species, a significant association was found between Pahoroides species and the plant hosts upon which they were collected. Pahoroides whangarei was found mostly on the foliage of crown fern (Blechnum discolor) and kiekie (Freycinetia banksii), whereas P. confusa was most often found in the fallen fronds of nīkau (Rhopalostylis sapida). Our findings support the hypothesis that the two Pahoroides species have similar habitat preferences at the macroscale, but not at the microscale. We conclude that host plant species is a dominant factor that enables the species to coexist.

Effects of interspecific alien versus intraspecific native competition on growth of native woody plants

The success of invasive plants and their impacts on community structure are commonly explained by referring to their supposed higher competitive ability. However, invasive plants do not consistently outperform native species; and the role of competition may also depend on the stage of the invasion process. This study investigated competitive effects of woody alien plant species at an early stage of invasion (Archontophoenix cunninghamiana and Psidium guajava) on closely related New Zealand native species of similar life form (Rhopalostylis sapida and Lophomyrtus bullata, respectively) at several points over time in a shadehouse experiment. Effects of interspecific competition from the paired alien species seedlings on a native seedling were compared to the effects from intraspecific competition of other seedlings of the native species over a 65 week period. Mortality was low throughout the experiment. The native species were affected by density-dependent competition generally, resulting in decreased performance with increasing neighbour density or biomass. The alien palm, A. cunninghamiana, however, had stronger competitive effects on the native palm, R. sapida, than intraspecific competition among R. sapida individuals. Also, P. guajava showed some stronger competitive effects on L. bullata than intraspecific competition among L. bullata individuals. These alien species displayed some traits often associated with invasive plants: A. cunninghamiana had higher RGR, height, biomass production and SLA than R. sapida, while P. guajava had higher SLA than L. bullata. Competitive ability of these newly naturalised species may be an important factor influencing their establishment success and subsequent invasion potential.

Predicting plant invasions under climate change: are species distribution models validated by field trials?

Climate change may facilitate alien species invasion into new areas, particularly for species from warm native ranges introduced into areas currently marginal for temperature. Although conclusions from modelling approaches and experimental studies are generally similar, combining the two approaches has rarely occurred. The aim of this study was to validate species distribution models by conducting field trials in sites of differing suitability as predicted by the models, thus increasing confidence in their ability to assess invasion risk. Three recently naturalized alien plants in New Zealand were used as study species (Archontophoenix cunninghamiana, Psidium guajava and Schefflera actinophylla): they originate from warm native ranges, are woody bird-dispersed species and of concern as potential weeds. Seedlings were grown in six sites across the country, differing both in climate and suitability (as predicted by the species distribution models). Seedling growth and survival were recorded over two summers and one or two winter seasons, and temperature and precipitation were monitored hourly at each site. Additionally, alien seedling performances were compared to those of closely related native species (Rhopalostylis sapida, Lophomyrtus bullata and Schefflera digitata). Furthermore, half of the seedlings were sprayed with pesticide, to investigate whether enemy release may influence performance. The results showed large differences in growth and survival of the alien species among the six sites. In the more suitable sites, performance was frequently higher compared to the native species. Leaf damage from invertebrate herbivory was low for both alien and native seedlings, with little evidence that the alien species should have an advantage over the native species because of enemy release. Correlations between performance in the field and predicted suitability of species distribution models were generally high. The projected increase in minimum temperature and reduced frosts with climate change may provide more suitable habitats and enable the spread of these species.

Habitat use, Behavior and Movement Patterns of a Threatened New Zealand Giant Weta,Deinacrida heteracantha(Anostostomatidae: Orthoptera)

Abstract Wetapunga (Deinacrida heteracantha), New Zealand's largest insect, were formerly abundant in forests of northern New Zealand. However, they are now restricted to onepopulation on mammal-free Little Barrier Island (3083 ha). This study investigated the movements, habitat use and behavior of 22 adult wetapunga fitted with miniature radiotransmitters for up to 18 nights. Adult wetapunga appeared to be quite mobile, with males (16 m per night) moving further than females (8 m per night). Differences in the distances travelled by adult male and female wetapunga between daytime refuges appear due to differences in reproductive behavior. Wetapunga were associated with silverfern, nikau palm, kanuka, and kohekohe within second-growth coastal forest on Little Barrier Island. The majority of wetapunga were found above ground level, but were also occasionally found moving on the ground. In addition, adult wetapunga were found in relatively open sites with little or no cover and were clearly visible by day. ...

Extended distribution and host plants of Nameriophyes sapidae Xue &amp;amp; Zhang 2008 (Acari: Eriophyidae) in New Zealand

Nameriophyes sapidae Xue &amp; Zhang (Acari: Eriophyidae) was found on transplanted nikau palms, Rhopalostylis sapida (H. Wendl. &amp; Drude) in Auckland, New Zealand and described as a new species (Xue &amp; Zhang 2008). Although R. sapida is a native plant species, it was not known if this mite species was indigenous or adventive because it was collected only from transplanted palms in unnatural gardens in Auckland. A survey was undertaken of R. sapida and the Kermadec Island palm, Rhopalostylis baueri (Hook. f.) Wendl. &amp; Drude in the northern part of the North Island and Chatham Island.

Myxomycetes associated with decaying fronds of nikau palm (Rhopalostylis sapida) in New Zealand

The assemblage of myxomycetes associated with the special microhabitat represented by the basal sheath of decaying fronds of nikau palm (Rhopalostylis sapida) in the forests of New Zealand was investigated. At least 37 species in 14 genera were represented among 280 field collections obtained from decaying fronds; the vast majority of species (89%) and of collections (>98%) consisted of members of the orders Physarales or Trichiales. Among the myxomycetes recorded from nikau palm were several species not previously known to occur in New Zealand or known from only one or two collections. Prominent examples include Badhamia gracilis, Craterium aureum, Diderma effusum, Physarum hongkongense, and P. pezizoideum.

A ‘ Phoebichnus look-alike’: a fossilised root system from Quaternary coastal dune sediments, New Zealand

Phoebichnus trochoides Bromley and Asgaard, is a large and unusual compound, deep-tier trace fossil described from the Jurassic of Jameson Land, Greenland and is of restricted occurrence in a few other Mesozoic sequences. The trace maker is an unknown marine organism. A remarkably similar structure, here called a ‘ Phoebichnus look-alike’ is preserved in a Quaternary coastal dune setting from northern New Zealand. This structure reflects the root architecture of the endemic nikau palm, Rhopalostylis sapida (Wendl et Drude). Apart from age, the only discernable difference between P. trochoides and the ‘ Phoebichnus look-alike’ is the absence of bi-directional, back-fill menisci in radiating rays of the latter. It is suggested that care should be taken when identifying the ichnotaxon P. trochoides ( s.s.) in the absence of these menisci. Structures of a ‘ Phoebichnus look-alike’ kind may be of local palaeoenvironmental significance and aid in the identification of damp, swaley environments in coastal sand dune settings.

Vegetation changes and their climatic implication for the late Pleistocene at Lake Poukawa, Hawkes Bay, New Zealand

A detailed vegetation history extending back to the Last Interglacial (Marine Isotope Substage 5e) is presented for Lake Poukawa, Hawkes Bay, New Zealand. This history is based on palynological analyses of a 198-m core record, age secured by uranium/thorium (U/Th) and optically stimulated luminescence (OSL) dates as well as tephrochronology. Vegetation of the penultimate glacial (Isotope Stage 6) probably consisted of a very sparse shrubby herbland of stunted podocarps ( Phyllocladus sp.), daisies, grasses and sedges. Similar floras existed in each of the succeeding cool periods. Four interglacial/interstadial floras are preserved. The peak of the Last Interglacial (Substage 5e) was dominated by extensive lowland forest of tall forest podocarps ( Podocarpus/Prumnopitys), most probably matai ( Prumnopitys taxifolia) with red beech ( Nothofagus fusca), secondary forest trees ( Coprosma spp., Myrsine spp.) and tree ferns ( Cyathea spp.). In the Poukawa basin itself, a swamp forest of the podocarp ( Dacrycarpus dacrydioides) with the true palm ( Rhopalostylis sapida) expanded. Substage 5e was significantly warmer and/or moister than the present day. Substage 5c/5a was marked by montane forest of red and silver beeches ( N. fusca and N. menziesii), Phyllocladus spp. and secondary trees. A reduced representation of Podocarpus/ Prumnopitys possibly consists of montane podocarp ( Podocarpus hallii). We infer the temperature of Substage 5c/5a to have been 3.5–5 °C lower than the present day. Although Stage 3 flora are superficially similar to those of Substage 5c/5a, the beeches are relatively less dominant. The regional flora during Stage 1 is very similar to those of Substage 5e, but the density is lower with no swamp forest during the present interglaciation. This may represent a change in evapotranspiration balance around Poukawa, but may also be controlled by hydrological conditions within the basin.

Depression of tree recruitment by the Pacific rat ( Rattus exulans Peale) on New Zealand's northern offshore islands

Recruitment of tree populations on islands with and without Rattus exulans Peale, and recruitment changes on islands before and after rat eradication are compared using size-class analyses. Seedling establishment in rat-proof exclosures was compared with adjacent control areas. R. exulans depress recruitment of 11 species of coastal trees among 17 species studied: Coprosma macrocarpa, Coprosma repens, Dysoxylum spectabile, Melicytus novae-zelandiae, Nestegis apetala, Pisonia brunoniana, Pittosporum crassifolium, Pouteria costata, Pseudopanax lessonii, Rhopalostylis sapida and Streblus banksii; some to the point of local extinction. Where R. exulans has reached small islands supporting dense colonies of petrels (Procellariidae, Pelecanoididae), the numbers of some plant and animal species have been greatly reduced. Successional pathways in vegetation recovering on larger islands formerly occupied by Maori, have also been altered by this rat. Similar effects by R. exulans on the plant life of Pacific islands are probable considering the length of time R. exulans has been present.

Polysaccharide compositions of primary cell walls of the palms Phoenix canariensis and Rhopalostylis sapida

The polysaccharide compositions of unlignified primary cell walls from two species of palms were examined. Cell-wall preparations were isolated from the stem apex, including the pre-emergent leaflets and rachides, of Phoenix canariensis (Canary Island date palm), and from leaflets and rachides dissected from pre-emergent leaves in the stem apex of Rhopalostylis sapida (Nikau palm). The non-cellulosic polysaccharides in the cell-wall preparations from both species had similar monosaccharide compositions, with arabinose and galactose being the predominant neutral monosaccharides, together with large amounts of galacturonic acid. These monosaccharide compositions indicated the presence of large proportions of pectic polysaccharides, including homogalacturonans. This was confirmed by linkage analyses of the cell-wall preparations which showed the presence of large proportions of pectic arabinans, together with pectic galactans and/or Type I arabinogalactans. Evidence for rhamnogalacturonan I and small amounts of rhamnogalacturonan II was also obtained. In addition to pectic polysaccharides, the cell-wall preparations contained smaller amounts of xyloglucans and even smaller amounts of heteroxylans, probably glucuronoarabinoxylans, and glucomannans and/or galactoglucomannans; (1→3,1→4)-β-D-glucans were not present. Although palms (Arecaceae) are commelinoid monocotyledons, the polysaccharide compositions of their primary cell walls resemble those of non-commelinoid monocotyledons and dicotyledons. These compositions contrast with those of primary cell walls of other commelinoid families which have glucuronoarabinoxylans rather than pectic polysaccharides as the major non-cellulosic polysaccharides. The results are discussed in relation to the possible evolution of the composition of primary cell walls of monocotyledons.

Post‐dispersal seed predation on eleven large‐seeded species from the New Zealand flora: A preliminary study in secondary forest

Seed predation trials were conducted for 11 large‐seeded species native to New Zealand in secondary forest. The species used were: Alectryon excelsus, Beilschmiedia tawa, Coprosma grandifolia, Corynocarpus laevigatus, Hedycarya arborea, Myoporum laetum, Nestegis cunninghamii, Prumnopitys ferruginea, Prumnopitys taxifolia, Rhopalostylis sapida, and Ripogonum scandens. Seed removal was monitored for 15 days for 160 seeds of each species, placed in piles of 5 seeds in each of 4 treatments at each of 8 sites in the Karori Wildlife Sanctuary, Wellington, in 1998. Removal of depulped seeds from treatments to which all species had access ranged from 3.8% to 23.8%, with a mean of 9.8%. No seeds were removed from the treatment that excluded all vertebrates. Presence of flesh on the seeds significantly increased seed removal rates in the three species tested with and without flesh. No relationship was found between seed removal and seed size, seed mass, or the proportion of the seed mass that was contributed by the seed coat. The seed removal rates reported here are exceptionally low, and suggest that the potential for post‐dispersal seed predation to limit regeneration of native forest in New Zealand may have been overestimated, at least in the forest type studied.

Four new Pirottaea species from New Zealand

Pirottaea falcata, P. horoeka, P. mahinapua, and P. palmicola spp. nov. are described from New Zealand. The fruiting bodies of three species form on dead leaf tissue: P. horoeka on Pseudopanax crassifolius (Araliaceae), P. mahinapua on Phormium tenax (Phormiaceae), and P. palmicola on Rhopalostylis sapida (Arecaceae). Those of P. falcata develop within the tomentum of living Olearia (Asteraceae) leaves. Lachnum willisii, also associated with the leaf tomentum of Asteraceae, is reported from New Zealand for the first time.

Germination behaviour of the seeds of six New Zealand woody plant species

Abstract Germination rates, percentage germination success, and phenomena related to germination delay were determined for one provenance each of seeds from freshly-collected fruit (summer-autumn) of Dodonaea viscosa, Hedycarya arborea, Pennantia corymbosa, Pseudowintera colorata, Rhopalostylis sapida, and Streblus heterophyllus. Dodonaea has wind-dispersed fruit; the fruit of the others are eaten by birds which disperse the seeds. The experimental treatments simulated natural conditions that the seeds might experience after dispersal. In the standard treatment (seeds cleaned, moist, well-lit) each species behaved differently. Streblus seeds began to germinate a few weeks after the start of the experiment and germination continued at a gradual, even rate through the winter. Hedycarya seeds began to germinate within three months and underwent a germination flush in mid-winter, then a levelling off before the last few seeds germinated in spring. A few Dodonaea seeds germinated in autumn and a few more in la...

Factors affecting reproductive behaviour in the New Zealand nikau palm,Rhopalostylis sapidaWendl. et Drude

Abstract Inflorescence and seed production was traced over seven consecutive years for the nikau palm, Rhopalostylis sapida, growing in temperate forests of northern New Zealand. Palms reach reproductive maturity when stems exceed a height of about 2.2 m, have about 60 frond scars, and are estimated to be approximately 90 years of age. However, inflorescences on young-mature palms usually aborted, and seed set was low for palms <3 m in height. Both the frequency of fruiting and the size of annual seed crops increased with increasing palm height to a maximum in the 6-8 m height class. However, the pattern of seed production in relation to number of frond scars (a better index of age) suggested declining seed production in old palms. Seed production varied up to three-fold between years and between sites. Seed production palm-1 yr-1 correlated positively with rates of frond fall (= frond production), inflorescences palm-1, and seeds inflorescence-1. Reproductive effort rarely exceeded 50%, possibly because ...

Population dynamics of the nikau palm,Rhopalostylis sapida(Wendl. et Drude), in a temperate forest remnant near Auckland, New Zealand

Abstract Survival, growth rate and fecundity are described for a population of the New Zealand nikau palm, Rhopalostylis sapida, based on six years of data for survival and growth, and seven years of data for fecundity. Transition matrix analyses were compared for height-classified (size) and frond scars-classified (approximate age) life-tables. Estimates of 1.004 (height), and 1.007 (scars), were obtained for the finite rate of increase, suggesting that this population is a numerically stable component of the temperate forest in which it is found. Nevertheless, differences between the initial and stable stage distributions, especially for the height-classified analysis, indicated that the present population size structure was not consistent with the measured rates of growth and survival. Specific disturbances over approximately the last 30–40 years may account for these differences. Measures of sensitivity, elasticity, and selective pressure revealed that the high survival rate for palms in the mature an...

Effects of introduced Australian brushtail possums(Trichosurus vulpecula) on the fruiting of the endemic New Zealand nikau palm(Rhopalostylis sapida)

Abstract Introduced Australian brushtail possums destroyed the large fleshy inflorescence of the endemic New Zealand nikau palm by browsing the flowers and eating through the base of the spadix. During 1978-83, when possum numbers were high, only one of nine nikau in a small area (8 ha) of podocarp/mixed hardwood forest fruited successfully. Eradication of possums in 1984-85 resulted in successful fruiting by all trees.