Podocarpus Species Research Articles

New podolactones from the seeds of Podocarpus nagi and their anti-inflammatory effect.

Podolactones are a class of structural diverse diterpenoid lactones, mainly isolated from the Podocarpus species. Several bioactivities have been disclosed for podolactones, including cytotoxicity and anti-atherosclerosis. In this study, the seeds of P. nagi were isolated by comprehensive chromatographic methods to obtain three new podolatones, named nagilactone B 1-O-β-D-glucoside (1), nagilactone N3 3-O-β-D-glucoside (2), and 2-epinagilactone B (3), as well as a known compound, nagilactone B (4). Their structures were determined by analyses of NMR and HRESIMS data. Compounds 1 and 2 significantly inhibited nitric oxide (NO) production on LPS-stimulated RAW264.7 macrophages, with IC50 values of 0.18 ± 0.04 and 0.53 ± 0.03μM, respectively. Indomethacin (IC50 4.21 ± 0.32μM) was used as a positive control. Compound 1 suppressed the expression of inducible NO synthase (iNOS) in a concentration-dependent manner, mediating through inhibiting nuclear factor-κB (NF-κB) activity. This is the first report regarding the anti-inflammatory effect of podolactones, which could be potential anti-inflammatory agents.

Contribution to the Enumeration and Study of the Podocarpus L’Hér. ex Pers. s.str. (Podocarpaceae) Taxa in Vietnam

Podocarpus is a small genus of conifers, having some scientific and economic values. Vietnam is recognised as one of 10 conifer “hotspots” in the world with 90% of total taxa threatened. Goal of this study is to enumerate taxa of the Podocarpus s. str. Methods of classical external morphology study are applied. 46 historical collecting numbers and 7 new collecting numbers were studied, revisedand hosted in HNU. Their scientific names were comparied with Protologue. Two native species Podocarpus pilgeri Foxw. and Podocarpus neriifolius D.Don with two varieties, var. neriifolius and var. annamiensis (N.E. Gray) L.K.Phan ms. and Podocarpus macrophyllus (Thunb.) Sweet as ornamental are listed. Annotations for each taxon mostly include the following informations: currently accepted scientific name, literature references to bona fide uses of these names, main synonyms used in regional literature, distribution, data on phenology, ecology, uses, Red List IUCN status, notes on taxonomy and biology and studied revised collections. Colour and characters of peduncles and seeds in the processing of their development were observed, described and illustrated by photos in details.

THE STOMATAL COMPLEX OF PODOCARPUS OBSERVED IN CROSS-SECTION USING CRYOFRACTURE: A PRELIMINARY STUDY

Cryofracture of living material and fracture at room temperature of herbarium material were used to obtain cross-sections of the stomatal complexes of four species of Podocarpus (Podocarpaceae) for scanning electron microscopy. Cross-sections of the stomata of one species in Podocarpus subgenus Foliolatus section Foliolatus (Podocarpus rubens), one in Podocarpus section Globulus (Podocarpus beecherae), one in Podocarpus subgenus Foliolatus section Longifoliolatus (Podocarpus insularis) and one in subgenus Podocarpus section Australis (Podocarpus nivalis) were studied. The architecture of the stomatal complex, including the wax plug, is described. It was found that the wax plug sits high in the stomatal antechamber in Podocarpus rubens, P. beecherae and Podocarpus decipiens and about halfway up the chamber in P. nivalis. A ridge, which appears to correspond to the crease where the guard cells meet, exists on the underside of the wax plug in Podocarpus beecherae, P. decipiens and P. rubens; its presence in P. nivalis requires confirmation. In addition, ridges within the stomatal antechamber were observed when viewing the cross-sections of Podocarpus decipiens and P. rubens, the internal surface of the cuticle of P. decipiens, Podocarpus teysmannii, P. insularis and Podocarpus milanjianus, and the external surface of the cuticle of Podocarpus chinensis, Podocarpus macrophyllus and Podocarpus pilgeri. These ridges may consist of wax and be a result of epitaxis.

Flora da Bahia: Podocarpaceae

The flora of Podocarpaceae, the only family of gymnosperms native to Bahia, Brazil, is presented here. Two species of Podocarpus are recognized: P. lambertii, occurring in the Chapada Diamantina region, and P. sellowii, occurring in the Chapada Diamantina and also in the montane and submontane forests in southern Bahia. Descriptions, identification key, illustrations and general comments on the taxa are presented.

A MONOGRAPHIC REVISION OF THE GENUS PODOCARPUS (PODOCARPACEAE): III. THE SPECIES OF THE CENTRAL AMERICA AND NORTHERN MEXICO BIOREGIONS

The species of Podocarpus L’Hér. ex Pers. (Podocarpaceae) occurring in the Central America and Northern Mexico Bioregions are revised. Four species (Podocarpus costaricensis de Laub., P. guatemalensis Standl., P. matudae Lundell, P. oleifolius D.Don) occur in these bioregions as well as three infraspecific taxa, that are here all treated as subspecies [Podocarpus matudae subsp. matudae, P. matudae subsp. jaliscanus (de Laub. & Silba) Silba, P. oleifolius subsp. costaricensis (J.Buchholz & N.E.Gray) Silba]. A fifth species, Podocarpus magnifolius J.Buchholz & N.E.Gray, may also be present in Panama but this requires verification; a brief account is provided. Podocarpus monteverdeensis de Laub. is considered a synonym of P. oleifolius subsp. costaricensis, the concept of which is amplified to include all Central American material of P. oleifolius. Several previously recognised infraspecific taxa within both Podocarpus guatemalensis and P. matudae are reduced to synonymy. Within Podocarpus matudae, P. matudae subsp. matudae is regarded as including subsp. macrocarpus and subsp. reichei but P. matudae subsp. jaliscanus is regarded as a distinct, second subspecies disjunct in westernmost Mexico. Podocarpus costaricensis, P. matudae (both subspecies) and P. oleifolius subsp. costaricensis are endemic to these bioregions. A key is provided, all definitely recorded species are illustrated and the distributions of all definitely recorded taxa are mapped. The distributions are discussed in relation to the geology and geological history of the region as well as altitude and climate. New IUCN conservation assessments are proposed for Podocarpus matudae subsp. jaliscanus, P. matudae subsp. matudae and P. oleifolius subsp. costaricensis while details of the current assessments for the remaining taxa (including Podocarpus matudae as a whole) are given. Two appendices list all accepted names and synonyms, and give a list of exsiccatae.

A DNA-based diagnostic for differentiating among New Zealand endemic Podocarpus

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 MONOGRAPHIC REVISION OF THE GENUS PODOCARPUS (PODOCARPACEAE): II. THE SPECIES OF THE CARIBBEAN BIOREGION*

The species of Podocarpus L’Hér. ex Pers. (Podocarpaceae) occurring on the islands of the Caribbean (excluding Trinidad and Tobago) are revised. Nine species are recognised, of which eight are known to be endemic to the Caribbean Bioregion. None of the species have infraspecific taxa. Four occur on Cuba, two on Hispaniola, two on Jamaica, and one on Puerto Rico and the Lesser Antilles. Keys are provided to all the species and to the species of Cuba, Hispaniola and Jamaica. The distributions of all species are mapped and discussed in relation to the geological history of the region as well as the climate, especially rainfall. The names Podocarpus urbanii Pilg. and Podocarpus buchii var. latifolius Florin are lectotypified. Revised or new IUCN conservation assessments are proposed for Podocarpus angustifolius, P. aristulatus and P. victorinianus and the existing assessments are detailed for the remaining species.

Underplanting degraded exotic Pinus with indigenous conifers assists forest restoration

SummaryWe 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.

Rescuing Robert Brown—The Origins of Angio-Ovuly in Seed Cones of Conifers

Robert Brown (1827) recognized the distinction between the two major classes of seed plants on the basis, respectively, of exposed ovules, which receive pollen directly, and enclosed ovules, which do not, at the time of pollination. The two groups, unfortunately, became known as “Gymnosperms” and “Angiosperms”, a distinction not made by Brown. The names are, at best, useful only as identifying labels. As is established here, gymno-ovuly and angio-ovuly would have been better words and should serve as the most consistent distinguishing character among groups of seed plants. Although conifers can hardly be claimed to be members of any lineage that led to the Angiosperms, the gymno-ovulate method of reproduction must have occurred in the direct ancestors of flowering plants. Interpolating development and functional evidence serves to resurrect Robert Brown’s important but neglected observation and correct misstatements implied in generally accepted systematic terminology. The result of this approach is to discover that the conifers in their reproductive diversity show some trends indicative of those characters that define the flowering plants. Although non-homologous these character manifestations provide useful models which can lead to a better understanding of the origin of “Angiosperms” from “Gymnosperms.” In the complex and extended process of reproductive development in both major groups regular transpositions occur, depending on whether “gymno-”and “angio-”are applied to ovules or seeds. Gymno-ovuly and angio-spermy are the most common conditions in conifers but result in intrinsically opposed processes of pollen reception and subsequent seed protection, which are resolved by successive changes in seed-cone structure. The modern conifers illustrate considerable diversity of ovulate and seed cone structure in relation to several biological functions, including traits that anticipate the angio-ovulate condition, in cone inception, ovule enclosure, pollen and embryo development and seed dispersal. From the paleobotanical record we do have a good grasp of the structural changes in the progressive modification of the coniferous seed cone in conifers, starting with the antecedent Carboniferous Cordaitales. These changes have involved the progressive condensation of a lax, branched strobilus and end with the highly condensed uniovulate “cone” as in many Podocarpus species in which the equivalent of a bitegmic ovule exists. The progressive changes can be perceived typologically among existing conifers but need to be understood as the result of biological processes that suggest increased reproductive efficiency, and can be added to our present quite robust understanding of conifer phylogeny.

Patterns of fungal diversity in New Zealand Nothofagus forests

The development of protocols for the conservation of fungi requires knowledge of the factors controlling their distribution, diversity, and community composition. Here we compare patterns of variation in fungal communities across New Zealand's Nothofagus forests, reportedly the most myco-diverse in New Zealand and hence potentially key to effective conservation of fungi in New Zealand. Diversity of leaf endophytic fungi, as assessed by culturing on agar plates, is assessed for three Nothofagus sp. growing in mixed stands from four sites. Host species was found to have a greater influence on fungal community assemblage than site. The leaf endophyte communities associated with Nothofagus solandri and Nothofagus fusca (both Nothofagus subgenus Fuscopora), were more similar to each other than either were to the community associated with Nothofagus menziesii (Nothofagus subgenus Lophozonia). The broad taxonomic groups isolated, identified on the basis of internal transcribed spacer (ITS) sequences, were similar to those found in similar studies from other parts of the world, and from an earlier study on the endophyte diversity in four podocarp species from New Zealand, but there were few matches at species level. Average levels of endophyte species diversity associated with single Nothofagus species and single podocarp species were similar, despite historical literature and collection data recording more than twice as many fungal species on average from the Nothofagus species. The significance of these findings to fungal conservation is discussed.

Mutagenicity, antimutagenicity and cytotoxicity evaluation of South African Podocarpus species

Ethnopharmacological relevanceFour species of Podocarpus are used in traditional medicine both in human and animal healthcare in South Africa. In vitro pharmacological screening of leaf and stem extracts of these species exhibited potent antimicrobial, anti-inflammatory, anti-tyrosinase, anthelmintic, acetylcholinesterase inhibitory and antioxidant activities. Aim of the studyTo investigate the mutagenicity, antimutagenicity and cytotoxicity effects of leaf and stem extract of South African Podocarpus species. Material and methodsThe mutagenicity and cytotoxic effects of extracts from four species of Podocarpus were tested using the Salmonella/microsome assay with and without metabolic activation, based on the plate-incorporation method and neutral red uptake (NRU) assay respectively. Five Salmonella typhimurium tester strains; TA98, TA100, TA102, TA1535 and TA1537 were used for mutagenicity testing. The relative cytotoxicity of the extracts was assessed by determining their NI50 values (50% inhibition of NRU). ResultsThe extracts did not show any mutagenic effects against all the tester strains with or without metabolic activation. All extracts demonstrated a strong antimutagenic effect on the mutations induced by 4NQO, decreasing its mutagenic effect in a dose-dependent manner. Strong cytotoxic effects were exhibited by petroleum ether extracts as compared to 80% ethanol extracts. When HepG2 cells were in contact with plant extracts in an increasing concentration, slopes of NRU decreased (highest–lowest %) following a concentration-dependent pattern. For 80% ethanol extracts, the most toxic extract in terms of percentage viability was leaves of Podocarpus falcatus whereby at 0.2mg/ml, the viability of the cells was 38.9%. Stem extract of Podocarpus latifolius was the most toxic among PE extracts, giving a percentage viability of 46.4 at 0.1mg/ml. ConclusionAbsence of mutagenicity does not indicate lack of toxicity, as was observed from these extracts. These findings will help in assessing the safety measures to be considered in the use of these species and also the need to determine the cytotoxic potential of these species against various forms of human cancer cells.

Cuticle Micromorphology of Caribbean and Central American Species ofPodocarpus(Podocarpaceae)

The cuticle micromorphology of leaves of 13 species of Podocarpus (Podocarpaceae), nine from the Caribbean Islands and four from Central America, was studied with scanning electron microscopy. They include five of the seven species of section Pumilis (Podocarpus aristulatus, P. buchii, P. ekmanii, P. urbanii, and P. victorinianus), four of the seven species of section Nemoralis (P. guatemalensis, P. hispaniolensis, P. purdieanus, and P. trinitensis), three of the six species of section Lanceolatus (P. coriaceus, P. costaricensis, and P. matudae), and one of the three species of section Pratensis (P. oleifolius). The external and internal features of the adaxial and abaxial cuticles are described for all species and are compared with other known Podocarpus species (especially section Scytopodium). Leaves are hypostomatic, with stomata arranged in discontinuous rows parallel to the leaf axis. The external cuticles of all studied species possessed Florin rings. Stomatal plugs were observed in all species except P. buchii and P. costaricensis. The number of subsidiary cells varies from two to six, with two or three being most common. Polar subsidiary cells are constantly absent in seven species and present in six species, although in three of these, they are sometimes absent. The internal cuticle on subsidiary cell surfaces is smooth to slightly rugose and is sometimes pitted. The cuticle on guard cell surfaces is usually granular to rugose, sometimes with pits. Polar extensions occur in all species; they are thin in the studied species of section Pumilis but thick in those belonging to the other three sections. Epidermal cell outlines are straight to undulating. The cuticle on epidermal cell surfaces is rugose and pitted in all the Caribbean species except for P. trinitensis but much smoother to granular in P. trinitensis and the Central American species. The most useful characters to distinguish species are the micromorphology of the cuticle on guard cell surfaces, the presence or absence of polar subsidiary cells, the periclinal epidermal cell texture, and the epidermal cell shape and size. No synapomorphic characters of the leaf cuticle were found that supported any of the sections proposed in the 1985 revision of Podocarpus by de Laubenfels, but some qualitative characters were correlated with geographical distribution. Quantitative characters showed considerable variation between species, often providing distinguishing characters, but none of this variation was correlated either with the current taxonomic classification or with geography.

Ecology of Fire-Tolerant Podocarps in Temperate Australian Forests

Podocarpus drouynianus and P. spinulosus are two unusual conifers restricted to southwestern and eastern Australia, respectively. The species are morphologically similar and genetically closely related to each other but rather distant from other members of the subgenus Foliolatus. Both species have retained ancestral podocarp characteristics such as dioecy, wind pollination, and large, animal-dispersed seeds with recalcitrant germination. They also thrive on soils with generally low nutrient content. However, they have several innovations that ensure their success in an environment that would generally be considered unsuitable for podocarps. Both species have much higher leaf length to width ratios than other Podocarpus species: this presumably aids their survival on low- to moderate-rainfall sites. They both resprout strongly after fires, and at least for P. drouynianus, seed production is cued by defoliation, and sporophylls are produced most prolifically on new growth one year after fire. The species are unique in the genus as being successfully adapted to a relatively dry, fire-prone environment.

The Ecology of Podocarps in Tropical Montane Forests of Borneo: Distribution, Population Dynamics, and Soil Nutrient Acquisition

We review the ecology of podocarps on various soil types in Borneo, largely relying on our studies conducted on Mount Kinabalu. Podocarps are generally abundant in montane forests, but their abundance varies with soil nutrient status, and they can occur in lowland forests where soil nutrients are scarce. These patterns suggest control by soil nutrients rather than by temperature. Analyses of population structure, growth rate, and crown light conditions in montane forests indicate that podocarps are generally shade intolerant and require canopy gaps or sparse canopy for regeneration. Podocarps have greater maximum tree sizes than most co-occurring angiosperm species in Mount Kinabalu forests. Once they reach the upper canopy layer, they persist for a long time because of their long life span, allowing them to regenerate in rare events of canopy disturbance. The roots of two podocarp species (Dacrycarpus imbricatus and Dacrydium gracile) showed a greater acid phosphatase activity when compared with angiosperm roots within the same lower montane forest. Moreover, an analysis using lipid biomarkers indicated that saprophytic fungi are more abundant in the soils beneath the two podocarps than beneath angiosperms, and a fungal biomarker lipid correlated with soil acid phosphatase activity. The dominance of saprophytic fungi appears to be related to high soil acid phosphatase activity, suggesting feedback effects between the podocarps and soil microbial communities. These results indicate that podocarps are efficient in the acquisition of phosphorus from the acidic montane soils and decomposing litter. We suggest that the architectural and life history advantages and physiological adaptations to nutrient limitation are essential for the persistence of podocarps, despite their lower shade tolerance as compared to angiosperms.

Ecology and Distribution of the Malesian Podocarps

Podocarp species and genus richness is higher in the Malesian region than anywhere else on earth, with maximum genus richness in New Guinea and New Caledonia and maximum species richness in New Guinea and Borneo. Members of the Podocarpaceae occur across the whole geographic and altitudinal range occupied by forests and shrublands in the region. There is a strong tendency for podocarp dominance of vegetation to be restricted either to high-altitude sites close to the limit of tree growth or to other sites that might restrict plant growth in terms of water relations and nutrient supply (e.g., skeletal soils on steep slopes and ridges, heath forests, ultramafic parent material). Although some species are widespread in lowland forests, they are generally present at very low density, raising questions concerning their regeneration ecology and competitive ability relative to co-occurring angiosperm tree species. A number of species in the region are narrowly distributed, being restricted to single islands or mountain tops, and are of conservation concern. Our current understanding of the distribution and ecology of Malesian podocarps is reviewed in this chapter, and areas for further research are identified.

Growth and competitiveness of the New Zealand tree species Podocarpus cunninghamii is reduced by ex-agricultural AMF but enhanced by forest AMF

The composition of arbuscular mycorrhizal fungi (AMF) communities found in agricultural systems has been found to be very different to that of forest. The implications of this, if any, for the restoration of indigenous forest on ex-agricultural land is poorly understood. This study investigated the effect that AMF communities isolated from ex-agricultural and forest soils have on the growth of an indigenous New Zealand tree species (Podocarpus cunninghamii). The forest AMF community was isolated from a remnant stand of P. cunninghamii forest and the ex-agricultural AMF from a retired grazing grassland. In addition, the study examined how the two AMF communities affected the competitiveness of P. cunninghamii when grown in competition with an invasive grass species (Agrostis capillaris), which is frequently dominant on ex-agricultural land in New Zealand. P. cunninghamii growth was significantly decreased by inoculation with ex-agricultural AMF compared to forest AMF. Furthermore, the forest AMF community was able to significantly increase P. cunninghamii root production when in competition with A. capillaris. The findings suggest that when attempting to restore indigenous forest on ex-agricultural land, inoculation of tree seedlings with appropriate forest AMF may improve their growth and survival.

Anti-inflammatory, antioxidant, anti-tyrosinase and phenolic contents of four Podocarpus species used in traditional medicine in South Africa

Species of Podocarpus are used traditionally in their native areas for the treatment of fevers, asthma, coughs, cholera, chest complaints, arthritis, rheumatism, venereal diseases and distemper in dogs. To investigate the antioxidant, anti-inflammatory and anti-tyrosinase activities of four Podocarpus species, Podocarpus elongatus, Podocarpus falcatus, Podocarpus henkelii and Podocarpus latifolius, used in traditional medicine in South Africa. Phytochemical analysis to determine the phenolic contents was also carried out. DPPH, FRAP and β-carotene-linoleic acid assays were used to determine the antioxidant/radical scavenging activities of these species. Anti-inflammatory activity of these species was assayed against two cyclooxygenase enzymes (COX-1 and COX-2). Tyrosinase inhibition activity was analysed using the modified dopachrome method with l-DOPA as the substrate. Phenolics were quantitatively determined using spectrophotometric methods. Stems of Podocarpus latifolius exhibited the lowest EC(50) (0.84 μg/ml) inhibition against DPPH. The percentage antioxidant activity based on the bleaching rate of β-carotene ranged from 96% to 99%. High ferric reducing power was observed in all the extracts. For COX-1, the lowest EC(50) value was exhibited by stem extracts of Podocarpus elongatus (5.02 μg/ml) and leaf extract of Podocarpus latifolius showed the lowest EC(50) against COX-2 (5.13 μg/ml). All extracts inhibited tyrosinase activity in a dose-dependent manner with stem extract of Podocarpus elongatus being the most potent with an EC(50) value of 0.14 mg/ml. The total phenolic content ranged from 2.38 to 6.94 mg of GAE/g dry sample. The significant pharmacological activities observed support the use of these species in traditional medicine and may also be candidates in the search for modern pharmaceuticals in medicine, food and cosmetic industries.

Diversity and distribution of fungal foliar endophytes in New Zealand Podocarpaceae

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.

Environmental controls and patterns of cumulative radial increment of evergreen tree species in montane, temperate rainforests of Chiloé Island, southern Chile

AbstractWe investigated the local environmental controls on daily fluctuations of cumulative radial increment and cambial hydration of three dominant, evergreen tree species from montane, Coastal rainforests of Chiloé Island, Chile (42° 22′ S). During 2 years (1997–1998 and 1998–1999) we recorded hourly cumulative radial increments using electronic band dendrometers in the long‐lived conifer Fitzroya cupressoides (Cupressaceae), the evergreen broad‐leaved Nothofagus nitida (Nothofagaceae), and the narrow‐leaved conifer Podocarpus nubigena (Podocarpaceae). We also measured soil and cambial tissue hydration using capacitance sensors, together with air and soil temperature and rainfall during the period of the study. In addition, we collected cores of these tree species to evaluate how dendrometer measurements reflect annual tree ring width. One‐year long daily time series of cumulative radial increments suggests that radial growth of Fitzroya cupressoides was initiated slowly in early spring, with a maximum in early summer. Multiple regressions showed positive relations between daily precipitation and radial index (i.e. the difference in cumulative radial increment of two consecutive days) in the three species. According to path analysis there was a significant direct effect of changes in tree hydration on radial index of the three focal species. In emergent, pioneer species such as Nothofagus and Fitzroya, radial index was negatively affected by changes in maximum air temperature and photosynthetically active radiation, probably because of high evapotranspiration demand on warm sunny days. The shade‐tolerant species Podocarpus nubigena was positively affected by photosynthetically active radiation. Our diel scale findings support the use of tree ring widths for reconstructing past climate in these southern temperate forests and provide evidence that rainforest trees may be highly sensitive to future declines in rainfall and temperature increases during summer.

Susceptibility of South African native conifers to the pitch canker pathogen, Fusarium circinatum

Fusarium circinatum is an economically important pathogen of Pinus species, which also occurs on Douglas fir (Pseudotsuga menzeisii). It causes pitch canker of mature trees and root and collar rot of seedlings and cuttings. In 2007, pitch canker was observed on Pinus radiata in the Western Cape and this was the first outbreak of this disease in South Africa. The Cape flora in this area includes native coniferous species of Podocarpus and Widdringtonia. In this study, seedlings of P. latifolia, P. elongatus, P. henkelii, W. schwartzii, W. cederbergensis and W. nodiflora were inoculated with a virulent isolate of F. circinatum, to assess their susceptibility. Six weeks after inoculation, there was no lesion development in any of the species inoculated. Pinus patula seedlings used as a positive control were severely affected. Results of this study show that species of Podocarpus and Widdringtonia, native to the Western Cape, are not threatened by the pitch canker fungus.