Seed rain and soil seed banks limit native regeneration within urban forest restoration plantings in Hamilton City, New Zealand

Restoration of native forest vegetation in urban environments may be limited due to isolation from native seed sources and to the prevalence of exotic plant species. To investigate urban seed availability we recorded the composition of seed rain, soil seed banks and vegetation at native forest restoration plantings up to 36 years old in Hamilton City and compared these with naturally regenerating forest within the city and in a nearby rural native forest remnant. Seed rain, soil seed banks (fern spores inclusive) and understorey vegetation in urban forest were found to have higher exotic species richness and lower native species density and richness than rural forest. Both understorey vegetation and soil seed banks of urban sites >20 years old had lower exotic species richness than younger (10–20 years) sites, indicating a developmental threshold that provided some resistance to exotic species establishment. However, the prevalence of exotic species in urban seed rain will allow reinvasion through edge habitat and following disturbance to canopy vegetation. Persistent soil seed banks from both urban and rural sites were dominated by exotic herbaceous species and native fern species, while few other native forest species were found to persist for >1 year in the seed bank. Enrichment planting will be required for those native species with limited dispersal or short-lived seeds, thus improving native seed availability in urban forests as more planted species mature reproductively. Further research into species seed traits and seedling establishment is needed to refine effective management strategies for successful restoration of urban native forests

Effect of Coriaria arborea on seed banks during primary succession on Mt Tarawera, New Zealand

An experiment was conducted over two years to investigate the effect of Coriaria arborea, a native nitrogen-fixing shrub, on soil seed banks at sites representing a post-volcanic successional sequence on Mt Tarawera, New Zealand. The sites ranged from bare volcanic ash and lapilli substrate, through low-growing pre-Coriaria vegetation, to dense stands of Coriaria scrub. Soils (to a depth of 50 mm) under recently established Coriaria and older stands had more seedlings (1096 and 1585 seedlings 0.4 m-2, respectively) and species (37 and 45 species 0.4 m-2, respectively) emerge than where there was no Coriaria (243-320 seedlings 0.4 m-2, 14-25 species 0.4 m-2) and were the only soils with Coriaria seedlings. In total, 3488 seedlings representing 63 taxa were recorded. Seeds were still germinating after 24 months but rates declined markedly in the second year. For example, Coriaria reached a germination peak at 8 weeks but continued to germinate sporadically over the 2-year period. Tree species present in young forest within 0.5 km of the sites were absent. Establishment of Coriaria greatly accelerated an underlying trend of gradually increasing abundance and diversity of seeds in the soil with vegetation age. Adventive, wind-dispersed, and annual species were over-represented in the seed banks compared with the regional evergreen forest-dominated flora. These proportions are expected to decline as succession to forest gradually occurs

A review of Leptospermum scoparium (Myrtaceae) in New Zealand

Information about Leptospermum scoparium (Myrtaceae), the most widespread and important New Zealand indigenous shrub species, is reviewed. L. scoparium is a variable species, requiring more study of the genetically based differences between New Zealand populations and the affinity of these populations to Australian populations and other closely allied Australian species. Improved understanding of the species’ variation will assist both its conservation roles and economic uses, and the need to sustain genetically distinct varieties is emphasised. Ecologically, the species has a dominant role in infertile and poorly drained environments, and a wider occurrence as a seral shrub species in successions to forest where it may be regarded as a woody weed of pasture or a useful species for erosion control, carbon sesquestration, and vegetation restoration. The main economic products derived from the species are ornamental shrubs, essential oils, and honey. The species’ development as an ornamental plant and further definition of the pharmacologically active components are recommended as priority areas for research

TRY plant trait database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Are current ecological restoration practices capturing natural levels of genetic diversity? A New Zealand case study using AFLP and ISSR data from mahoe (Melicytus ramiflorus)

Sourcing plant species of local provenance (eco-sourcing) has become standard practice in plant community restoration projects. Along with established ecological restoration practices, knowledge of genetic variation in existing and restored forest fragments is important for ensuring the maintenance of natural levels of genetic variation and connectivity (gene flow) among populations. The application of restoration genetics often employs anonymous ‘fingerprinting’ markers in combination with limited sample sizes due to financial constraints. Here, we used two such marker systems, AFLPs and ISSRs, to estimate population-level genetic variation of a frequently used species in restoration projects in New Zealand, māhoe (Melicytus ramiflorus, Violaceae). We examined two rural and two urban forest fragments, as potential local source populations, to determine whether the māhoe population at the recently (re)constructed ecosystem at Waiwhakareke Natural Heritage Park (WNHP), Hamilton, New Zealand reflects the genetic variation observed in these four potential source populations. Both marker systems produced similar results and indicated, even with small population sizes, that levels of genetic variation at WNHP were comparable to in situ populations. However, the AFLPs did provide finer resolution of the population genetic structure than ISSRs. ISSRs, which are less expensive and technically less demanding to generate than AFLPs, may be sufficient for restoration projects where only a broad level of genotypic resolution is required. We recommend the use of AFLPs when species with a high conservation status are being used due to the greater resolution of this technique

A provisional survey of the interaction between net photosynthetic rate, respiratory rate, and thallus water content in some New Zealand cryptogams

The effect of water content on photosynthetic and respiratory rates in eight lichen species and one bryophyte species were studied using an injection infrared gas analyser technique. All species snowed a strong relationship between net assimilation rate (NAR), respiration rate, and water content similar to relationships reported in published studies overseas. Species from moist habitats showed negative NAR at low water contents. Species from high-light areas showed a depression in NAR at high water contents which could be alleviated by higher light intensities. The experiments confirmed the suitability of New Zealand species for these studies

Manual of tropical bryology

Bryophytes belong to the oldest land plants. They existed already in the Palaeozoic 300 mio years ago in forms which were hardly different from the extant species. They remained relatively unchanged with relatively low evolution rates (and are thus often called a „conservative“ plant group), but could successfully establish themselves in an always varying environment from Devonian swamps to Permian forests, Mesozoic deserts and as epiphytes in Tertiary rainforests. They are not eaten by snails or insects, and are resistant against fungi and bacteria

Coordination of Foliar and Wood Anatomical Traits Contributes to Tropical Tree Distributions and Productivity along the Malay-Thai Peninsula

Drought is a critical factor in plant species distributions. Much research points to its relevance even in moist tropical regions. Recent studies have begun to elucidate mechanisms underlying the distributions of tropical tree species with respect to drought; however, how such desiccation tolerance mechanisms correspond with the coordination of hydraulic and photosynthetic traits in determining species distributions with respect to rainfall seasonality deserves attention. In the present study, we used a common garden approach to quantify inherent differences in wood anatomical and foliar physiological traits in 21 tropical tree species with either widespread (occupying both seasonal and aseasonal climates) or southern (restricted to aseasonal forests) distributions with respect to rainfall seasonality. Use of congeneric species pairs and phylogenetically independent contrast analyses allowed examination of this question in a phylogenetic framework. Widespread species opted for wood traits that provide biomechanical support and prevent xylem cavitation and showed associated reductions in canopy productivity and consequently growth rates compared with southern species. These data support the hypothesis that species having broader distributions with respect to climatic variability will be characterized by traits conducive to abiotic stress tolerance. This study highlights the importance of the well-established performance vs. stress tolerance trade-off as a contributor to species distributions at larger scales