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Background: Tree carbon estimates for New Zealand indigenous tree and shrub species are largely based on mean basic stem-wood densities derived from a limited number of trees, often of unspecified age and from a limited number of sites throughout New Zealand. Yet stem-wood density values feed directly into New Zealand’s international and national greenhouse gas accounting. We augment existing published basic stem-wood density data with new age-specific values for 12 indigenous forest and shrubland species, including rarely obtained values for trees

Tree ferns are recognized as “keystone” species for their role in casting deep shade on forest floor environments, acting as a differential ecological filter on forest regeneration processes. Tree fern dominance is a feature of New Zealand’s central North Island exotic Pinus radiata (Pinaceae) plantations, particularly beyond 20 years following plantation establishment. In circumstances where plantation forests are managed for restoration of indigenous forest species, rather than timber harvest, an understanding of the competitive role of dense tree fern stands on forest regeneration processes in these “non-harvest” plantations is necessary. We investigated the competitive effect of tree fern (Cyatheaceae and Dicksoniaceae) cover on seedling growth rates of two mature forest tree species, Podocarpus totara (Podocarpaceae) and Pittosporum eugenioides (Pittosporaceae), over two austral summers in five 36–92-year P. radiata plantations. We experimentally manipulated tree fern canopies in order to contrast heavy versus light shading. Tree fern removal significantly increased the growth rate of both P. totara and P. eugenioides , and the growth rate of the shorter-lived, faster-growing, light demanding P. eugenioides was greater than that of P. totara with tree fern removal. Damage to the seedlings by mammalian animal browsers when tree ferns were removed was greater than that occurring under tree fern cover. This damage diminished the effect of tree fern removal on seedling growth rates for P. totara , but not for the faster growing P. eugenioides . The physical clearance of tree fern stands and then the establishment of fast growing, locally representative, indigenous canopy tree species of low palatability, along with protection from animal browse, are suggested restoration strategies. Our results are consistent with existing literature in showing that where tree ferns are a dominant feature of plantation understories, deep shade is likely to reduce canopy species seedling growth rates, reducing the potential for forest regeneration.

We created small-scale artificial canopy gaps to accelerate the growth of mature indigenous forest canopy species for restoration of an 18-year-old exotic Pinus radiata plantation forest, in the Marlborough Sounds, New Zealand. Small and large circular gaps were formed by felling. Seedlings of two indigenous forest canopy species, Podocarpus totara (Podocarpaceae) and Beilschmiedia tawa (Lauraceae), were planted within artificial gaps and undisturbed plantation canopy. Seedling height growth, mortality, and occurrence of animal browse were monitored at approximately 6-month intervals over 17 months. Both P. totara and B. tawa differed significantly in height growth and in animal browse occurrence among artificial gap treatments. Growth of the light-demanding P. totara was better under large canopy gaps, whereas growth of the shade-tolerant B. tawa increased under gaps of any size but was most consistent under small gaps. For P. totara, any significant restoration benefit of gap formation on height growth was lost when browsed seedlings were taken into account. Animal browse significantly limited B. tawa height growth in large but not in small gaps. Small-scale canopy gap creation is an effective method of modifying light transmission to the plantation understorey and accelerating seedling growth rates. Canopy gap size can be used to optimize understorey illumination according to species-specific light requirements. The increased occurrence of animal browse in gaps requires consideration. Artificial canopy gaps within planted monocultures create structural heterogeneity that would otherwise take an extended period of time to develop. These results further support the role of plantations as indigenous forest restoration sites.

Background Tree allometric equations are critical tools for determining tree volume, biomass and carbon stocks. However, there is a lack of species-specific biomass equations for juvenile trees of many of New Zealand’s indigenous species. The aim of this study was to provide allometric equations for total above- and below-ground biomass and total root biomass and length for eight common evergreen conifer and broadleaved species. Methods In a plot-based field trial, growth metrics of conifers Prumnopitys taxifolia (matai), Agathis australis (kauri), Prumnopitys ferruginea (miro), Podocarpus totara (totara), Dacrycarpus dacrydioides (kahikatea) and Dacrydium cupressinum (rimu) and broadleaved species Alectryon excelsus (titoki) and Vitex lucens (puriri) were measured annually. These species were selected based on their potential role as a long-term solution for mitigating erosion in areas of marginal land proposed for new afforestation/reforestation and as an important carbon (C) sink. Results Root collar diameter (RCD) provided the best fit for tree height, total above-ground biomass (AGB) and total below-ground biomass (BGB), and all regressions were highly significant (P = 0.001). Most species showed significant increases in annual growth and, by year 5, the BGB ranged between 21 and 42% of total biomass and decreased with increasing plant age. Of the conifers, Podocarpus totara had the greatest mean maximum root spread (2.2 m) exceeded only by the broadleaved Vitex lucens (2.5 m). For all species, and in each year of the trial, 100% of the BGB remained confined to within 0.5 m of the ground surface. With the exception of Vitex lucens and Podocarpus totara, > 90% of the total root length remained within a 0.5-m radius of the root bole. The species-specific mean tree biomass of 5-year-old plants ranged from 0.32 to 4.28 kg plant−1. A mixed-species forest established at 1000 stems per hectare (spha), consisting of 200 of each of the best performed of the trialled species, would amass ~ 2.3 t ha−1 of biomass and a forest carbon stock of 3.8 t CO2 ha−1 within 5 years. Conclusions Inter-species differences in the allocation of BGB and AGB appeared to be age dependent. The root-growth metrics of these common indigenous forest species, as candidates for erosion control, have improved our understanding of their potential usefulness for stabilising marginal land. Whole-plant biomass of juvenile trees will greatly improve the accuracy of current estimates of forest carbon stocks for proposed new areas of indigenous afforestation/reforestation.

Most plants change shape as they grow. However, ontogenetic changes in morphology (i.e. heteroblasty) can differ markedly among species and the role that heteroblasty might play in plant defence is poorly resolved. We use a model selection approach to characterise heteroblasty in terminal leaf spines produced by two perennial plant species native to New Zealand. Aciphylla aurea (Apiaceae), a perennial herb that inhabits alpine scrublands, exhibited ‘progressive’ heteroblasty. Seedlings produced soft, entire leaves with sharpened tips. However, as plants matured they produced compound leaves with sharpened tips that were far more rigid, giving rise to a strong degree of spinescence at adulthood. By contrast, Podocarpus totara (Podocarpaceae), a tall tree inhabiting cool-temperate forests, exhibited ‘retrogressive’ heteroblasty. The size of terminal leaf spines decreased during development and leaf circularity increased. Furthermore, leaf rigidity peaked at intermediate heights resulting in a peak in termin...

Summary We propose that nonharvest plantations could provide important opportunities for restoration of indigenous forest cover and related ecosystem services. We assessed the relative performance of three Podocarpaceae (podocarps) species planted into a degraded Ponderosa Pine (Pinus ponderosa) plantation, central North Island, New Zealand. We hypothesised that the degraded pine plantation overstorey could provide suitable conditions for the development of a podocarp-dominated forest structure within ca. 50 years of underplanting and that podocarp growth would differ depending on the species suitability to the site. Rimu (Dacrydium cupressinum) significantly outperformed both Totara (Podocarpus totara) and Kahikatea (Dacrycarpus dacrydioides) in height and diameter growth. Rimu was now the structurally dominant tree where it occurred rather than pine. Per annum scaled carbon storage within Rimu stands was significantly greater than the Totara, Kahikatea or Pine stands. All podocarp species had attained a greater stand density compared to the pine overstorey. Possible reasons for the differing podocarp growth performance include different light requirements, response to soil nutrients, elevational distributions and frost susceptibility. There were significant differences in understorey species richness among the different stands of podocarp species. Underplanting accelerated successional development by incorporating late-successional indigenous canopy dominants within the forest succession and overcame limitations imposed on forest succession at the site from its isolation from indigenous forest tree seed sources.

The diversity and distribution of fungal endophytes in the leaves of four podocarps (Dacrydium cupressinum, Prumnopitys ferruginea, Dacrycarpus dacrydioides, and Podocarpus totara, all Podocarpaceae) and an angiosperm (Kunzea ericoides, Myrtaceae) occurring in close stands were studied. The effects of host species, locality, and season on endophyte assemblages were investigated. Host species was the major factor shaping endophyte assemblages. The spatial separation of sites and seasonal differences played significant but lesser roles. The mycobiota of each host species included both generalist and largely host-specialised fungi. The host-specialists were often observed at low frequencies on some of the other hosts. There was no clear evidence for family-level specialisation across the Podocarpaceae. Of the 17 species found at similar frequencies on several of the podocarp species, 15 were found also on Kunzea. Many of the endophytes isolated appear to represent species of fungi not previously recognised from New Zealand.

Species of the genus Podocarpus are primarily found in the Southern Hemisphere. In New Zealand, there are four endemic species—Podocarpus acutifolius, Podocarpus nivalis, Podocarpus totara and Podocarpus cunninghamii. The last mentioned two species, tōtara and Hall’s tōtara, are the most economically and culturally important and have been used extensively for carving, timber and medicinal purposes. However, these species are often difficult to distinguish morphologically as seedlings and adults. Useable Po. totara and Po. cunninghamii timber resources are now scarce, and replanting of tōtara is very costly; therefore, cheap diagnostics for ensuring species identity would be useful for replanting. Using expressed sequence tag (EST)-aligned genomic DNA sequences from putative Po. totara × Po. cunninghamii hybrids, we designed 120 primers for high-resolution melting (HRM) assays. These were evaluated in a multi-stage screening process to identify markers that discriminate among New Zealand endemic Podocarpus species. Ten markers reproducibly differentiated at least one species from the other three, and six differentiated two or more species. One marker differentiated all four species. Moreover, two markers were able to identify ‘artifical’ F1 hybrids of Po. totara and Po. cunninghamii that had been created from mixing equal amounts of DNA from one genotype of each species. Markers also differentiated a non-New Zealand endemic, Podocarpus lawrencei. Phylogenetic analyses indicated that Po. acutifolius accessions were genetically most similar to those of Po. totara, while Po. nivalis was the most genetically distinct species. Our results show that HRM markers can be easily developed from small amounts of next-generation sequence data and used to identify species and determine their phylogenetic relationships.

A 1.2 m sediment core from Lake Forsyth, Canterbury, New Zealand, records the development of the catchment/lake system over the last 7000 years, and its response to anthropogenic disturbance following European settlement c. 1840 AD. Pollen was used to reconstruct catchment vegetation history, while foraminifera, chironomids, Trichoptera, and the abundance of Pediastrum simplex colonies were used to infer past environmental conditions within the lake. The basal 30 cm of core records the transition of the Lake Forsyth Basin from a tidal embayment to a brackish coastal lake. Timing of closure of the lake mouth could not be accurately determined, but it appears that Lake Forsyth had stabilised as a slightly brackish, oligo-mesotrophic shallow lake by about 500 years BP. Major deforestation occurred on Banks Peninsula between 1860 AD and 1890 AD. This deforestation is marked by the rapid decline in the main canopy trees (Prumnopitys taxifolia (matai) and Podocarpus totara/hallii (totara/mountain totara), an increase in charcoal, and the appearance of grasses. At around 1895 AD, pine appears in the record while a willow (Salix spp.) appears somewhat later. Redundancy analysis (RDA) of the pollen and aquatic species data revealed a significant relationship between regional vegetation and the abundance of aquatic taxa, with the percentage if disturbance pollen explaining most (14.8%) of the constrained variation in the aquatic species data. Principle components analysis (PCA) of aquatic species data revealed that the most significant period of rapid biological change in the lakes history corresponded to the main period of human disturbance in the catchment. Deforestation led to increased sediment and nutrient input into the lake which was accompanied by a major reduction in salinity. These changes are inferred from the appearance and proliferation of freshwater algae (Pediastrum simplex), an increase in abundance and diversity of chironomids, and the abundance of cases and remains from the larvae of the caddisfly, Oecetis unicolor. Eutrophication accompanied by increasing salinity of the lake is inferred from a significant peak and then decline of P. simplex, and a reduction in the abundance and diversity of aquatic invertebrates. The artificial opening of the lake to the Pacific Ocean, which began in the late 1800s, is the likely cause of the recent increase in salinity. An increase in salinity may have also encouraged blooms of the halotolerant and hepatotoxic cyanobacteria Nodularia spumigena.

Bark thickness has been said to be the key character in distinguishing Podocarpus totara from P. hallii. However, even this character has proved difficult to use, especially in the southern South Island coastal dune forests dominated by species of Podocarpus. Five stands of such forests were sampled in which bark thickness and tree diameter at breast height (dbh) of 527 trees were measured. Linear regression and analysis of variance indicated that bark‐thickness:dbh ratios differed between sites. Two hypothetical regression lines were constructed to represent what seemed to be, from the data, pure P. totara (a steep slope) and P. hallii (a shallow slope). At all sites, the actual thickness:dbh slope over all trees was intermediate between the hypothetical P. totara and P. hallii slopes. However, two sites seemed to be almost pure P. totara, perhaps with hybrids from a nearby stand of P. hallii in one case, and the other three sites comprised various mixtures of the two species, in many cases incl...

A detailed study of the levels of sesquiterpenoids and diterpenoids in essential oils from 36 specimens of Podocarpus hallii from two populations has revealed considerable infraspecific variation both within and between populations. The unusual tetracyclic diterpene laurenene, which has previously been encountered only in Podocarpus totara and Dacrydium cupressinum, was found at low levels in several of the samples.

There is increasing interest in establishing indigenous forests on marginal pastoral hill country in New Zealand to improve soil conservation, water quality and indigenous biodiversity. Large-scale reforestation using native seedlings is extremely costly. However, given suitable seed sources, it is possible to encourage natural regeneration of grassland into native plants. A grazed, sloping pasture site in Northland where totara (Podocarpus totara D.Don) regeneration had been allowed to develop over a 10-year period was assessed using a grid of 2-metre diameter plots. Counts of regenerating woody species and cover of herbaceous species were obtained in each plot. Plots were classified on the basis of herbaceous species cover using the TWINSPAN classification procedure. Regression analyses were used to identify site factors and characteristics of the herbaceous vegetation associated with totara regeneration. More than 7,000 stems ha−1 of woody species, mostly totara and gorse (Ulex europaeus L.), had accumulated over the 10-year period despite the presence of cattle grazing. Regeneration of totara was associated with steeper slopes and sites with the greatest diversity of herbaceous species but with lower overall levels of herbaceous cover. The regeneration pattern of the other main woody species was similar although gorse colonised a wider range of sites. Regeneration of woody species was absent on flatter sites, which were dominated by a few high-fertility tolerant herbaceous species and had high levels of herbaceous cover. This study has shown that regeneration of totara on a pastoral hill-country site was most prevalent on steeper slopes of lower fertility with typically sparse vegetation cover comprising low fertility tolerant herbaceous species. Conversely, totara regeneration was absent on flatter areas of higher fertility. It seems likely that grazing assists totara regeneration by keeping pasture cover short, thus increasing light levels near ground level for newly germinated seedlings. The propensity for totara to regenerate on pastoral hill country in the presence of grazing and where there is a nearby seed source could provide a practical option for re-establishing indigenous woody vegetation on erosion-prone marginal land.

Totarol, a diterpenoid phenol isolated from Podocarpus totara (D. Don ex Lambert) root bark, was found to be active against second- and fourth-instar Culex pipiens Coquillett with the 24 h LC50 values of 0.25 and 0.37 μg/mL, respectively. The mosquito larvicidal activity against C. pipiens increased when bioassays were extended to 48 h. Structural elucidation of totarol was by means of 1H-NMR, 13C-NMR, and GC-MS analysis.

The silviculture and ecology of the New Zealand endemic tree Podocarpus totara (totara) relevant to management for timber production, either in plantations or in managed, naturally regenerating second‐growth stands, is reviewed. There is increasing interest in information on the management of tree species indigenous to New Zealand for a range of objectives including timber production. Previous studies and observations have identified a range of features that make totara a species worthy of further evaluation for growing as a specialty timber tree. These include its cultural and heritage values; durability and machining qualities of the wood; wide distribution; tolerance of a wide variety of sites; ease with which seedlings can be raised in a nursery; good growth rates; potential genetic gains in both growth and form; and amenability to tending. There is also a range of non‐timber benefits in managing a long‐term resource of totara. In addition to the interest in planting and managing totara for t...

Seventeen monoterpenoids, six sesquiterpenoids, and nine diterpenoids have been identified by GC/MS in the essential oil of the mature foliage of Podocarpus totara G. Benn ex D. Don. The major monoterpenoids were α-pinene, sabinene, limonene, α-terpinene and α-terpineol. The major sesquiterpenes were β-elemene, α-humulene, β-caryophyllene, and β-selinene, while the major diterpenes were 13-isopropylpodocarpa-6,13-diene, rimuene and kaurene. The oil also contained 2,10,10-trimethyl-6-methylidene-1-oxaspiro(4,5)dec-7-ene, a theaspirane. In addition, the oil contained many unidentified minor components, especially sesquiterpene alcohols or epoxides.

A reproductive cycle of totara ( Podocarpus totara ) in New Zealand is complete within 2 years. After strobilus initiation in September, there is a 9 month period of winter dormancy until emergence during the growth flush in July–August of the following year. Female strobili bear only one or two ovules which are pollinated mid-October to mid-November at the megaspore tetrad stage. Pollen germination and fertilization occur rapidly during December. The pollen tube carries the body cell, sterile and tube nuclei with at least three prothallial nuclei, and branches out after reaching the archegonia. The four–six archegonia contain egg nuclei with no distinct perinuclear zone and a large chalazal vacuole. Fertilization by the larger of the two unequal male gametes is accompanied by a degradation of egg cell cytoplasm. The three-tier proembryo contains a binucleate embryonal tier of only one cell. Soon after embryo penetration into the megagametophyte, the binucleate embryonal-tier cell undergoes mitosis and cell wall formation resulting in four uninucleate cells. Some ovules contained secondary embryos thought to be the product of suspensor cleavage. Embryo maturation occurs by February.

The comparative growth of seedlings of Dacrycarpus dacrydioides, Podocarpus totara, Dacrydium cupressinum, Prumnopitys ferruginea, and P. taxifolia was investigated at different light levels. Five light regimes were achieved using shade cloth for glasshouse seedlings (2–25% of full sunlight) and under different canopy vegetation types (5–30% of full sunlight) in dense lowland podocarp forest at Whirinaki Forest Sanctuary, Central North Island, New Zealand. Height growth, stem diameter growth, and dry weight increase were measured for a 15 month period over two spring seasons in both glasshouse and forest environments. The five podocarp species show significant differences in height growth, stem diameter growth, and dry weight increase under the different light regimes of both glasshouse and forest environments. Seasonal height growth rates were examined in the forest, and species exhibited different responses to the climatic parameters of rainfall, humidity, temperature, and solar radiation. Comp...

New natural sources are reported for the unique rosettane diterpene, (−)-lauren-1-ene ( 1 ) along with the structure of the first laurenene-related plant metabolite. This new compound ( 4 ), isolated from the New Zealand podocarp, Podocarpus totara var waihoensis and named waihoensene, has a perhydro-4H-pentaleno[6a,1- c ]indene ring system. Waihoensene is a double bond position isomer of a compound which has been formed previously by acid treatment of laurenene.

A modified serum‐based bioassay was used to screen plant extracts and assess compound activity against newly hatched larvae of the Australian sheep blowfly Lucilia cuprina. Larval instar mortality and physical appearance were recorded after exposure for 24 h to the treatments. Extracts from New Zealand gymnosperms shown to have activity against L. cuprina larvae were: Podocarpus totara; P. acuteafolius; Dacrycarpus dacrydioides; Halocarpus bidwillii; H. biformis; H. kirkii; Lagarostrobos colensoi; Lepidothamnus intermedius; L. laxifolius; Phyllocladus tricho‐manoides; P. glaucus, and Agathis australis. The phytoecdysones 20‐hydroxyecdysone, 5,20‐dihydroxyecdysone, and ponasterone A inhibited larval moulting. Dyshomoerythrine, dacrysterone, and nagilactone C were insecticidal, with the latter also retarding growth at sublethal rates.

New natural sources are reported for the unique rosettane diterpene, (−)-lauren-1-ene ( 1 ) along with the structure of the first laurenene-related plant metabolite. This new compound ( 4 ), isolated from the New Zealand podocarp, Podocarpus totara var waihoensis and named waihoensene, has a perhydro-4H-pentaleno[6a,1- c ]indene ring system. Waihoensene is a double bond position isomer of a compound which has been formed previously by acid treatment of laurenene.

The effect of the 1987-89 drought on the native vegetation of bush remnants on Banks Peninsula was examined using measurements of water potentials and growth, and ordination of species composition. Marked individuals of five species (Alectryon excelsus, Helichrysum aggregatum, Kunzea ericoides, Melicytus ramiflorus, and Podocarpus totara) were studied in detail in Ahuriri Valley. The drought was severe, whether judged by visual appearance (extensive wilting and leaf fall), water potentials (≤-7.1 MPa), or survival (three of the marked individuals died). Water potentials were initially very low, but most plants eventually recovered. One K. ericoides plant had all five samples below -7 MPa in December 1988 yet still survived. Growth was reduced, however, with narrower growth rings in A. excelsus and shorter leaves in P. totara during the drought. The first ordination axis of vegetation samples from the reserve matched the rainfall/moisture gradient, suggesting that water availability is important i...

The late-winter frost hardiness of seedlings of eight provenances of totara (Podocarpus totara G. Benn. ex Don) raised in a common environment was tested in a controlled environment frost room. Frost damage was assessed visually. Frost hardiness temperatures of the provenances ranged from -5°C to -10°C. A significant increase in frost damage occurred at lower temperatures, and the frost hardiness of the provenances was positively comelated with their altitude of origin. The possibility of allele frequency-dependent selection for alleles correlated with frost hardiness was explored by apreliminary isozyme analysis of four variable loci in new foliage of totara seedlings. Allele frequencies at one locus of isocitrate dehydrogenase (Idh-1) appeared significantly correlated with provenance frost hardiness. These results suggest that environmental pressures have selected far frost hardiness in totara, and resulted in the evolution of populations of totara adapted to current local climates.

The relationship between seedlings and saplings of four podocarp tree species (Prumnopitys ferruginea, Podocarpus totara, Dacrydium cupressinum, and Dacrycarpus dacrydioides) and overhead cover was investigated in a coastal forest fragment, Hokitika Ecological District, New Zealand Significantly more podocarp seedlings and saplings occurred under angiosperm trees, especially Weinmannia racemosa, than under podocarp trees. This pattern is similar to that described in other studies and may in part be due to dispersal of seed away from parent trees and to higher forest floor irradiances under angiosperm tree canopies than under podocarp canopies. The observed positive association between podocarp regeneration and angiosperm canopy tree species suggests that angiosperm trees play a key role in the dynamics of these forests.