New Zealand Ferns Research Articles

Epiphyte-host relationships of remnant and recombinant urban ecosystems in Hamilton, New Zealand: the importance of Dicksonia squarrosa (G.Forst.) Sw., whekī

ABSTRACT More than a thousand iNaturalist NZ observations were compiled and analysed to determine common vascular epiphyte-host relationships in Hamilton, North Island, New Zealand. Dicksonia squarrosa supported the most epiphytes, followed by Salix cinerea, Melicytus ramiflorus and Cyathea medullaris. Epiphytes displaying stronger host specificity, such as Tmesipteris elongata and Phlegmariurus varius, were often on D. squarrosa. In comparison, generalist epiphytes, including Pyrrosia eleagnifolia and Lecanopteris pustulata, were mainly on M. ramiflorus and S. cinerea. A detailed study of 60 D. squarrosa in a single gully investigated factors supporting the host quality of D. squarrosa. Dicksonia squarrosa diameter at breast height (DBH), height, caudex surface area, and distance to the stream and vegetation patch edge were measured. Dicksonia squarrosa that hosted epiphytes were significantly taller, further from the patch edge and had a larger surface area. Epiphyte species richness was higher on D. squarrosa further from the patch edge. The epiphyte communities examined are likely characteristic of highly modified urban ecosystems. Future research investigating the impact of host traits and microclimate on epiphyte-host networks is required to fully elucidate these relationships in urban environments.

Restoration Strategies for Three Dacrycarpus dacrydioides (A.Rich.) de Laub., Kahikatea Remnants in Hamilton City, New Zealand

Identifying appropriate restoration strategies is vital for successful urban remnant restoration, but projects often lack consistent methods that distinguish them. In New Zealand, there are unique opportunities to restore depleted Dacrycarpus dacrydioides (A.Rich.) de Laub. (kahikatea, white pine) semi-swamp forest remnants in numerous urban centres. To assess potential restoration strategies for three kahikatea remnants in Hamilton City, we compared their physical features, native vascular species composition, age structures, life forms and epiphytes with a notional reference site (Te Papanui). Numerous native vascular species gaps are revealed among Te Papanui (66 species), Totara Park (40 species), Hillcrest Park (15 species) and Grove Park (nine species). Age structure analyses suggest that Hillcrest Park comprises the oldest kahikatea population, with an average age of 82 years, followed by Grove Park (70 years), Te Papanui (60 years) and Totara Park (32 years). A native floristic analysis of thirteen life forms found that Te Papanui contains the most (11), followed by Totara Park (eight), Grove Park (six) and Hillcrest Park (five). Despite the abundance of invasive plants at Totara Park, its high-water table and favourable humid, sheltered conditions support more epiphytes (nine) than Te Papanui (six), Hillcrest Park (one; Pyrrosia eleagnifolia), and Grove Park (none). Epiphytes absent from Te Papanui found at Totara Park may be due to the loss of the once abundant tree fern and host, Dicksonia squarrosa (whekī). Totara Park requires careful manipulation of troublesome weeds, whereas Hillcrest Park and Grove Park necessitate buffer extensions and native understory plantings. This study provides a simple framework that uses biophysical differences among urban remnants and a reference site to reveal suitable restoration strategies that could guide other urban restoration projects regionally and nationally.

Glyphosate redirects wetland vegetation trajectory following willow invasion

AbstractAimsAerially applied glyphosate is an economic tool to deal with large areas of invasive plants. However, there are few studies investigating non‐target effects or rates of reinvasion, particularly over multi‐year time frames. The aims were to evaluate the effectiveness of aerial application of glyphosate for control of dense stands of the invasive grey willow Salix cinerea, and determine the vegetation trajectory over the subsequent 2 yr.LocationWhangamarino Wetland, Waikato, New Zealand.MethodsA before–after control–impact (BACI) experiment was conducted in a Ramsar‐listed wetland in New Zealand. Effects on S. cinerea cover, canopy light interception and non‐target damage were monitored over a 7.1 ha experimental area prior to, and for 2 yr following, aerial application of glyphosate. Vegetation classification, ordination and species richness analyses were undertaken to describe community‐level effects.ResultsAerial application of glyphosate to an established willow canopy was effective in reducing cover to <5% on average for up to 2 yr post‐spray when assessed using 100 m2 vegetation survey plots. Smaller 1 m2 plots were more sensitive for detecting willow reinvasion, which was noted from 1 yr post‐spray. Collateral damage to non‐target sub‐canopy species was generally minimal, except for the native tree fern Dicksonia squarrosa, which showed marked reductions in cover and no recovery over the study period. Species richness was higher in sprayed plots post‐spray and a shift towards a native Carex‐dominated sedgeland community was detected.ConclusionsAerial application of glyphosate to a dense canopy of mature willow was effective in reducing the cover and dominance of this invasive wetland tree species. Minimal collateral damage occurred, facilitating recovery and expansion of a native sedgeland community. The risk of secondary invasion did not eventuate, although exotic species richness spiked in the year following spraying. Sedgelands are susceptible to willow reinvasion via seed, so longer‐term trajectories will diverge depending on management intensity. Using currently available tools, the management options are either repeated cycles of herbicide application to redirect the trajectory from reinvasion to short‐statured sedgelands, or intensive initial management to establish an alternative, more resilient trajectory to native wetland forest.

Long-term tree fern dynamics linked to disturbance and shade tolerance

Question: Do New Zealand tree ferns have recognizable shade tolerance niches? Location: Lowland temperate rain forest of New Zealand (41°20′S, 174°58′E). Methods: Growth, death and recruitment of five tree fern species were estimated from a 38-year record of stem heights, collected within a 2.25-ha block of forest, and electron transport rates (ETR) of photosystem II of fronds were measured. Results: Two species of Cyathea were comparatively common (603 and 351 stems in total) and two were comparatively rare (155 and 17 stems in total) on the site. The common species had lower rates of growth, recruitment and mortality than the rare species, had skewed age distributions typical of shade-tolerant species and were probably recruited soon after a catastrophic earthquake in 1855. The two rare species were failing to recruit under closed forests; their age distributions indicated that all had regenerated long after the earthquake. ETR were higher for faster-growing than for the shade-tolerant species. A tree fern that regenerates vegetatively from aerial buds, Dicksonia squarrosa, was common on the site (361 stems in total). Its age distribution suggested it was relatively shade tolerant, but its mortality and recruitment rates were much higher than those of the two shade-tolerating Cyathea species, suggesting that this multi-stemmed species functions differently from the monopodial Cyathea species. Conclusions: New Zealand Cyathea tree ferns occupy distinct niches along a shade tolerance spectrum and their relative abundances are strongly influenced by disturbance history. The study provides evidence that tree fern species differ strongly in their responses to canopy disturbance and are not ecologically equivalent.

Experimental study of terrestrial plant litter interaction with aqueous solutions

Quantification of silicon and calcium recycling by plants is hampered by the lack of physico-chemical data on reactivity of plant litter in soil environments. We applied a laboratory experimental approach for determining the silica and calcium release rates from litter of typical temperate and boreal plants: pine ( Pinus laricio), birch ( Betula pubescens), larch ( Larix gmelinii), elm ( Ulmus laevis Pall.), tree fern ( Dicksonia squarrosa), and horsetail (Equisetum arvense) in 0.01 M NaCl solutions, pH of 2–10 and temperature equals to 5, 25 and 40 °C. Open system, mixed-flow reactors equipped with dialysis compartment and batch reactors were used. Comparative measurements were performed on intact larch needles and samples grounded during different time, sterilized or not and with addition or not of sodium azide in order to account for the effect of surface to mass ratio and possible microbiological activity on the litter dissolution rates. Litter degradation results suggest that the silica release rate is independent on dissolved organic carbon release (cell breakdown) which implies the presence of phytoliths in a pure “inorganic” pool not complexed with organic matter. Calcium and DOC are released at the very first stage of litter dissolution while Si concentration increases gradually suggesting the presence of Ca and Si in two different pools. The dry-weight normalized dissolution rate at circum-neutral pH range (approx. 1–10 μmol/g DW/day) is 2 orders of magnitude higher than the rates of Si release from common soil minerals (kaolinite, smectite, illite). Minimal Ca release rates evaluated from batch and mixed-flow reactors are comparable with those of most reactive soil minerals such as calcite and apatite, and several orders of magnitude higher than the dissolution rates of major rock-forming silicates (feldspars, pyroxenes). The activation energy for Si liberation from plant litter is approx. 50 kJ/mol which is comparable with that of surface-controlled mineral dissolutions. It is shown that the Si release rate from the above-ground forest biomass is capable of producing the Si concentrations observed in soil solutions of surficial horizons and contribute significantly to the Si flux from the soil to the river.

Tree fern trunks facilitate seedling regeneration in a productive lowland temperate rain forest

Seedling regeneration on forest floors is often impaired by competition with established plants. In some lowland temperate rain forests, tree fern trunks provide safe sites on which tree species establish, and grow large enough to take root in the ground and persist. Here we explore the competitive and facilitative effects of two tree fern species, Cyathea smithii and Dicksonia squarrosa, on the epiphytic regeneration of tree species in nutrient-rich alluvial forests in New Zealand. The difficulties that seedlings have in establishing on vertical tree fern trunks were indicated by the following observations. First, seedling abundance was greatest on the oldest sections of tree fern trunks, near the base, suggesting that trunks gradually recruited more and more seedlings over time, but many sections of trunk were devoid of seedlings, indicating the difficulty of establishment on a vertical surface. Second, most seedlings were from small-seeded species, presumably because smaller seeds can easily lodge on tree fern trunks. Deer browsing damage was observed on 73% of epiphytic seedlings growing within 2 m of the ground, whereas few seedlings above that height were browsed. This suggests that tree ferns provide refugia from introduced deer, and may slow the decline in population size of deer-preferred species. We reasoned that tree ferns would compete with epiphytic seedlings for light, because below the tree fern canopy photosynthetically active radiation (PAR) was about 1% of above-canopy PAR. Frond removal almost tripled %PAR on the forest floor, leading to a significant increase in the height growth rate (HGR) of seedlings planted on the forest floor, but having no effects on the HGRs of epiphytic seedlings. Our study shows evidence of direct facilitative interactions by tree ferns during seedling establishment in plant communities associated with nutrient-rich soils.

The annual diet of feral goats (Capra hircusL.) in lowland rimu-rata-kamahi forest on eastern Mount Taranaki (Mt Egmont)

Abstract The diet of the feral goat (Capra hircus) in rimu-rata-kamahi forest on Mt Taranaki was examined over 1 year from monthly rumen samples. Seasonal changes in diet, relative plant preference ratings, and differential fragmentation and digestion rates of plant species, were measured. Individual rumens contained 19 plant species on average and sometimes more than 30. Two species, (Asplenium bulbiferum and Ripogonum scandens), made up 44.8% of the total volume eaten over the year. Foods which were eaten in significantly different proportions by season included Coprosma grandifolia, Coprosma tenuifolia, Griselinia littoralis, Melicytus ramiflorus, Ripogonum scandens (fruit and vine), Weinmannia racemosa, and Dicksonia squarrosa. Goats selected or rejected different plant species largely independently of plant availability. Schefflera digitata was relatively scarce in the habitat, but was possibly the most preferred food. In contrast, the very abundant Microlaena avenacea, Uncinia spp., moss, Alsophila ...

Biogeochemical exploration for tungsten at Barrytown, New Zealand

Biogeochemical prospecting for tungsten was carried out at a mineralised area near Barrytown, New Zealand. The tungsten content of the ash of the shallow-rooted tree ferns Cyathea medullaris and Dicksonia squarrosa correlated well with the concentrations of this element in the soil. Sampling of these species therefore provides a possible method of detecting general soil anomalies and moreover is considerably faster than soil sampling under local conditions. Trend surface analysis of the concentrations of tungsten in the trunks of all species of common large evergreen trees sampled on belt transects, could be used to delineate extensions of known tungsten mineralisation in bedrock, and was to some extent superior to soil geochemistry in this respect.

Prothallia of the Cyatheaceae

1. Under favorable conditions the plate stage follows very quickly after germination; there is ordinarily no filament left at the base of the prothallium. The mature prothallium usually is longer and the cushion heavier than in the Polypodiaceae. Forking of the cushion of the prothallium occurs frequently in old cultures, and in certain species may occur in relatively young prothallia. 2. Multicellular hairs were found to develop more or less abundantly on mature prothallia of all species of Alsophila, Hemitelia, and Cyathea, and to occur rarely on Lophosoria. None were found on Thyrsopteris, Culcita, Cibotium, or Dicksonia. The multicellular hair arises from a special initial, a wedge-shaped cell cut from the anterior face of a superficial cell near the apical meristem. The hairs are found on both dorsal and ventral surfaces, on or near the cushion, but not on the margin. The hairs may reach a length of 2 mm. 3. The wall of the antheridium typically consists of five cells: an oblique basal cell, a lower ring cell with a "binding wall" on one side; an upper ring cell, an opercular cell, and a crescent-shaped cell formed by the division of the cap cell. Many variations from this type occur. The antheridia of Lophosoria are larger and less symmetrical than those of Alsophila, Hemitelia, and Cyathea. Those of Thyrsopteris are the largest and least symmetrical of the family, ordinarily not conforming to the type just given. The antheridia of the Dicksonieae are usually larger than those of the Cyatheae. 4. The necks of the archegonia in the Cyatheae are straight or slightly curved; they have more cells in the neck and are longer than those of the Polypodiaceae. Those in the Dicksonieae and Thyrsopteris are longer than those of the Cyatheae, and are more apt to be recurved. The walls of the neck cells are more or less cutinized. The neck contains two neck canal nuclei not separated by a wall. Archegonia with four neck canal nuclei were found in all species. 5. Apogamous growths were found in Lophosoria quadripinnata, Alsophila excelsa, A. armata, Hemitelia parvula, Cyathea medullaris, C. dealbata, Thyrsopteris elegans, Dicksonia squarrosa, Cibotium barometz, and C. schiedii. 6. The evidence from the gametophyte indicates that the family Cyatheaceae, in the broader sense, is not a natural group, but is of polyphyletic origin.