Native Vascular Plant Species Research Articles

Interaction of multiple disturbances: importance of disturbance interval in the effects of fire on rehabilitating mined areas

Abstract Multiple disturbance regimes are increasingly common as novel anthropogenic disturbances are added to existing natural disturbances. However, it is generally unknown whether simultaneous or sequential effects of different forms of disturbance are predictable from the independent effects of each disturbance. This study examines the short‐term effects of sequential disturbance by mineral sand‐mining followed by fire in a forest community in south‐eastern Australia. Four combinations of disturbance were sampled: unburned mined, burned mined, unburned forest (unmined) and burned forest (unmined, with between‐fire interval matching the disturbance interval between mining and fire of the burned mined treatment). All combinations were sampled approximately 12 months following fire on the burned sites. The impact of fire after mining depended on disturbance interval. Sites burned 0.5–2.4 years since mining had fewer native vascular plant species than unburned mined sites of the same mined age, whereas sites with 10–16 years or 20–26 years between mining and fire had greater native species richness than unburned mined sites of the same age. Burning 20–26 years after mining brought native species richness within the range of burned forest. For both unmined and mined sites native seedling densities increased with burning, and with longer disturbance intervals. Weed species richness and weed seedling densities were greater on mined sites than in forest, and burning mined sites elevated weed seedling densities further, particularly for short intervals. Both disturbance interval and fire intensity are likely to have contributed to these results, as intensity on mined areas increased with interval, and at 20–26 years post‐mining was equivalent to unmined forest. These results suggest that fire could be used to promote rehabilitation of these mined areas after at least 10 years, but should be excluded from earlier stages of post‐mining regeneration. However, other sources of spatial and temporal variability should be considered in addition to interval and intensity, as variation among mined areas was correlated with post‐fire weather conditions and available weed sources. Finally, the combined effects of mining and fire could not be predicted from knowledge of the disturbances operating separately, indicating that effects of multiple disturbance may be synergistic rather than additive.

Scottish vascular plants in a global conext

Summary A recent reassessment of the flora of Scotland has provided an estimate of 1000 native vascular plant species, excluding c. 350 microspecies in the genera Hieracium, Rubus and Taraxacum. The figure can only be approximate, as there are uncertainties about what constitutes a species and which accepted species are native. The total is lower than the equivalent totals for tropical or warm-temperate regions of similar area, and this almost certainly reflects the climatic differences between the regions as well as the recent glacial history of Scotland. The 50 oceanic species in Scotland are clearly important on a world scale; Scottish populations of species which are more widespread but currently declining in Europe may also be important but are difficult to identify in the absence of Europe-wide data on such floristic trends. Compared to other groups, the British ferns and fern-allies are extremely well represented in Scotland and flowering plants moderately well represented. The ferns include a large proportion of species in predominantly tropical genera. Scottish vascular plant species which are rare or scarce in Britain fall predominantly into the northern floristic elements. Of the eleven Scottish endemic vascular plant species currently recognised only Primula scotica appears to be manifestly distinct, thus calling into question the current very great emphasis on the conservation of endemic species.

Species richness and endemism in the Western Australian flora

AbstractAim Estimates of endemic and non‐endemic native vascular plant species in each of the three Western Australian Botanical Provinces were made by East in 1912 and Beard in 1969. The present paper contains an updated assessment of species endemism in the State.Location Western Australia comprises one third of the continental Australian land mass. It extends from 13° to 35° S and 113° to 129° W.Methods Western Australia is recognized as having three Botanical Provinces (Northern, Eremaean and South‐West) each divided into a number of Botanical Districts. Updated statistics for number of species and species endemism in each Province are based on the Census of Western Australian Plants data base at the Western Australian Herbarium (Western Australian Herbarium, 1998 onwards).Results The number of known species in Western Australia has risen steadily over the years but reputed endemism has declined in the Northern and Eremaean Provinces where cross‐continental floras are common. Only the isolated South‐West Province retains high rates of endemism (79%).Main conclusions With 5710 native species, the South‐West Province contains about the same number as the California Floristic Province which has a similar area. The Italian mediterranean zone also contains about this number but in a smaller area, while the much smaller Cape Floristic Region has almost twice as many native species. The percentage of endemic species is highest at the Cape, somewhat less in south‐western Australia and less again in California. Italy, at 12.5%, has the lowest value. Apart from Italy, it is usual for endemism to reach high values in the largest plant families. In Western Australia, these mainly include woody sclerophyll shrubs and herbaceous perennials with special adaptations to environmental conditions. While those life forms are prominent in the Cape, that region differs in the great importance of herbaceous families and succulents, both of which are virtually absent from Western Australia. In California and Italy, most endemics are in families of annual, herbaceous perennial and soft shrub plants. It is suggested that the dominant factor shaping the South‐West Province flora is the extreme poverty of the area’s soils, a feature that emphasizes sclerophylly, favours habitat specialization and ensures relatively many local endemic species.

New or rediscovered native vascular plant species in British Columbia

New or rediscovered native vascular plant species in British Columbia

Species turnover on a protected subtropical barrier island: a long‐term study

Abstract. The commercial development that threatens the biodiversity of coastal habitats is particularly severe along the sandy shores of subtropical Florida. The objective of our study was to test the applicability of the equilibrium theory of island biogeography to Cayo‐Costa Island, the largest protected barrier island remaining in peninsular Florida. Our null hypothesis was that there would be no change in the number and composition of native vascular plant species on Cayo‐Costa 15 years after the first inventory of the island's flora. Our reinventory documents a total of 230 native species in 1990–92 compared to 255 native species in 1975–77. Immigrants were represented by twenty‐eight new species, while extinctions totalled fifty‐three species. These results indicate a turnover rate of approximately 2.7 species yr‐1 with an extinction rate of 3.5 species yr‐1 and an immigration rate of 1.9 species yr‐1. The net loss of 1.6 species yr‐1 suggests a non‐equilibrium condition that is not readily explained by changes in habitat diversity associated with the documented patterns of shoreline erosion and deposition. Cayo‐Costa's net loss of twenty‐five native species (including one tree species and four shrub species) was localized mainly in those habitats where there had been a significant increase in the relative abundance of the naturalized weedy exotic species Schinus terebinthifolius and Casuarina equisetifolia. We conclude that the spread of naturalized weedy species limits the applicability of the equilibrium theory of island biogeography to species‐rich subtropical barrier islands, even in cases where the islands are protected from human disturbance.

The Reservation Status of Plant Species and Vegetation Types in the Northern Territory

The terrestrial conservation reserve system of the Northern Territory comprises 83 reserves covering 3.79% of the land area. This system includes representation of only 63 of the 112 vegetation types recognised in the Northern Territory at 1:1000000 scale. Of these, only 31 are represented to at least 5% of their extent. The reserve system has a strong geographic bias, with very poor representation of vegetation types occurring across a broad band in the mid-latitudes of the Northern Territory. Broad vegetation categories which are particularly poorly reserved include tussock grasslands, chenopod shrublands, Acacia woodland and hummock grasslands: by contrast, closed forests and floodplains have > 20% of their extent reserved. In some contrast to the poor reservation extent of vegetation types, 80% of the 3632 named native vascular plant species known from the Northern Territory have been recorded from reserves. The distribution of the 743 unreserved plants is mapped, and coincides reasonably well with the pattern of unreserved vegetation types. The high proportion of the flora which is reserved is due in part to judicious (or fortuitous) reserve placement-for example, one reserve, Kakadu, contains almost half of the plant species known from the Northern Territory. There are substantial taxonomic and ecological biases in the reported reservation rates for NT plants. Rainforest plants tend to be reasonably well reserved (80% of 585 species), but designated threatened plants are poorly reserved(44% of 553 species). Due to its largely intact environment, the Northern Territory offers an unusually good opportunity for the establishment of a comprehensive reserve network. However, most of the unreserved plants and vegetation types occur on either freehold Aboriginal lands or pastoral leaseholds, suggesting that substantial enhancement of the existing reserve network may not be simple.

Vegetation and flora of Womens Island, Foveaux Straft, New Zealand

Abstract Womens Island of 8 ha, one of the muttonbird islands north-east of Stewart Island, has a flora of 44 native species of vascular plants plus 12 adventives. Its steep sides support several coastal communities: Poa astonii on rock headlands, P. foliosa on deep peat fringing sheltered clifftops, mats of Disphyma australe on cliffs with thin soil, and the last two species codominant over several other coastal herbs on exposed shores. Hebe elliptica scrub covers the north end, but low forest of Olearia angustifolia encircles the rest of the island. The gently sloping top is dominated by low Myrsine chathamica scrub, scattered O. × traillii, and dense ferns, especially Asplenium obtusatum and Phymatodes diversifolium. The Myrsine community, which may have resulted from a fire in about 1926, and the presence or absence of many plant species make Womens Island botanically distinct from nearby islands. The origin of O. × traillii is discussed.