Patterns of air temperature and accumulation of snow in subalpine heathlands and grasslands on the Bogong High Plains,Victoria

On well drained sites in the subalpine tract of the Bogong High Plains, Victoria, the distribution of grassland, dominated by Poa spp., and closed heathland, dominated by Prostanthera cuneata, can be correlated with patterns of maximum and minimum air temperature, and the accumulation and persistence of snow. Both maximum and minimum temperatures are lower, and the accumulation and persistence of snow is less in grassland, the dominant community of gentle slopes and hollows, than in closed heathland, the dominant community on steeper, leeward slopes. On gentle slopes and in hollows, the development of closed heath may be limited by the accumulation of cold air, relatively low temperatures and exposure to strong winds. However, on leeward slopes where snow persists the longest (until mid-late December), the development of heath may be limited by a shortening of the growing season. The distribution of grassland and heathland, especially the limits to the distribution of the heath, may also be affected by infrequent climatic events, such as the co-incidence of unusually low temperatures during winters when snow cover is meagre.     

Looking to the future: key points for sustainable management of northern Great Plains grasslands

The grasslands of the northern Great Plains (NGP) region of North America are considered endangered ecosystems and priority conservation areas yet have great ecological and economic importance. Grasslands in the NGP are no longer self‐regulating adaptive systems. The challenges to these grasslands are widespread and serious (e.g. climate change, invasive species, fragmentation, altered disturbance regimes, and anthropogenic chemical loads). Because the challenges facing the region are dynamic, complex, and persistent, a paradigm shift in how we approach restoration and management of the grasslands in the NGP is imperative. The goal of this article is to highlight four key points for land managers and restoration practitioners to consider when planning management or restoration actions. First, we discuss the appropriateness of using historical fidelity as a restoration or management target because of changing climate, widespread pervasiveness of invasive species, the high level of fragmentation, and altered disturbance regimes. Second, we highlight ecosystem resilience and long‐term population persistence as alternative targets. Third, because the NGP is so heavily impacted with anthropogenic chemical loading, we discuss the risks of ecological traps and extinction debt. Finally, we highlight the importance of using adaptive management and having patience during restoration and management. Consideration of these four points will help management and restoration of grasslands move toward a more successful and sustainable future. Although we specifically focus on the NGP of North America, these same issues and considerations apply to grasslands and many other ecosystems globally.     

Feeding and movement of Anguilla australis and A. reinhardtii in Macleods Morass, Victoria, Australia

Feeding and movement of Anguitta australis Richardson, and A. reinhardtii Steindachner, were studied in Macleods Morass, Gippsland, Victoria from July 1975 to March 1977. Stomach fullness varied seasonally. Both species ingested a wide range of items with teleosts and insects forming the major group for A. australis and teleosts the major group for A. reinhardtii , which fed on a narrower range of items. No relationship between size of items ingested and size of eel was evident. Kendall rank correlation coefficients indicate that both intraspecific and interspecific differences in diets due to seasonal and size variations were usually insignificant.
Tagged eels were recaptured at the overall rate of 18·5 %; of 1051 eels released, a total of 194 eels was recaptured. Maximum linear distance travelled by two eels was 3715 m while maximum days at liberty was 643 days. Home range was in the order of 400m. No relationship between length of a tagged individual and days liberty or with distance moved was evident. Movement was closely related to fluctuations of water temperature with peaks being associated with feeding in the littoral zone of the Morass.     

Colonization by alpine native plants of a stabilized road verge on the Bogong High Plains, Victoria

Summary Although many native species are now used in the revegetation of soil disturbances in Australian alpine areas, exotic species were, until recently, the only components of seed mixes. The use of exotic species and fertilizer was justified by their availability and low cost, and the prediction that native species would replace the exotic sward, presumably once soil nutrient levels dropped to those found in native vegetation. There was no apparent regard for the invasive capacities of the exotic species used. An investigation of a road verge on the Bogong High Plains, revegetated with a mixture of exotic species in the late 1950s, has shown that colonization by native plants can be very slow. Although many native species had colonized by 1993, exotic species still provided 50% of the cover. Agrostis capillaris accounted for most of this. The major native colonizers were Carex spp., Colobanthus affinis , Euchiton spp., Leptinella filicula , Poa hiemata , Ranunculus victoriensis and Scleranthus biflorus . Poa hiemata provided by far the most cover of the native colonizers. There have been considerable increases in the cover and number of native species on the verge since 1989. Cattle grazing and trampling are likely to have limited colonization of native plants prior to the removal of livestock in 1991. Recommendations are made on approaches to future revegetation in the alpine area.     

Composition and seasonal flux of the soil seed bank of species-rich Themeda triandra grasslands in relation to burning history

Abstract. Most species-rich grasslands dominated by Themeda triandra in southeastern Australia have been ungrazed and frequently burnt for decades. The seedling emergence technique was used to determine the size and taxonomic composition of the soil seed bank of five grasslands that had different fire histories (i.e. burnt at 1 yr, 3 yr and > 10 yr intervals) and this was compared to the standing vegetation at each site. A nested sampling design (subplot, plot, site) was used to determine the effect of spatial scale on the patterns observed in both the vegetation and the seed bank. Temporal variation in the seed bank was assessed by repeated soil sampling over a two year period. 61 native and 30 exotic species were recorded in the vegetation. Richness varied more between sites than within sites. Sites were therefore internally homogeneous for species richness. However, no correlation between burning frequency and richness was found. DCA ordination separated the sites into distinct groups, but sites with similar fire history did not necessarily group closely. 60 taxa germinated from the soil seed bank, comprising 32 native and 28 exotic species; 11 species, mostly therophytes, were restricted to the seed bank. The richness of the seed bank was significantly lower than the vegetation at all spatial scales. No correlation between seed bank richness and fire history was found. The seed bank of species-rich grasslands is dominated by a limited number of widespread, highly clumped, annual, native and exotic monocots. Most native hemicryptophytes, and perennials in general, were represented in the soil by a transient seed bank. Only 12 % of study species, all therophytes, were considered to form large, persistent seed banks, the size of which was greater in unburnt grasslands at all times of the year. The distinct floristic patterns observed in the vegetation are less clearly represented in the seed bank. The seed bank represents a floristically distinct (and less variable) component of the vegetation when compared to the standing flora. The size of the long-term soil seed bank suggests that it has little functional importance for many native species and probably contributes little to seedling regeneration processes following disturbance. Altering established fire regimes is likely to only change the composition and small-scale richness of the existing site vegetation and will not re-integrate species previously lost from the vegetation due to past management. It is suggested that the maintenance of vegetation remnants and processes that encompass a range of long-term burning histories will be necessary if the flora is to be conserved in situ. Restoration of degraded grasslands cannot rely on the soil seed bank but rather, will be dependent on the reintroduction of propagules.     

Discriminating and mapping the C3 and C4 composition of grasslands in the northern Great Plains,USA

There is uncertainty about the extent and distribution of grasslands following the C3 and C4 photosynthetic pathways. Since these grasses have an asynchronous seasonal profile it should be possible to estimate and map the C3–C4 composition of grasslands from multi-temporal remote sensing imagery. This potential was evaluated using 30 weekly composite MERIS MTCI images for South Dakota, USA. Derived relationships between the remotely sensed response and composition of grasslands were significant, with R² ∼ 0.6. It also appears possible to map broad classes of grassland composition, with a three class (high, medium and low C3 cover) classification having an accuracy of 77.8%.     

Abundance,species richness and feeding preferences of introduced molluscs in native grasslands of Victoria,Australia

Abstract Introduced molluscs have invaded endangered, remnant native grasslands of south‐eastern Australia, but few studies have investigated their distribution, abundance or potential impact. Molluscs were surveyed in grassland sites across an urban to rural transect west of Melbourne, Australia. It was confirmed that several introduced mollusc species have invaded these areas. Three snail and five slug species were identified, none of which was native to Australia. The most common species was the brown field slug (Deroceras panormitanum). Mollusc capture and species richness were positively related to the degree of urbanization in the surrounding landscape. There was also a negative relationship with fire frequency. Feeding trials revealed selective herbivory by the black‐keeled slug (Milax gagates) among native plants. Anecdotal evidence that variable glycine (Glycine tabacina) and button wrinklewort (Rutidosis leptorrhynchoides) are palatable to molluscs was supported. Mollusc herbivory may potentially lead to reduced fitness of palatable species, and changes in community composition and structure.     

Leaf domatia in Korean plants: floristics,frequency, and biogeography

Leaf domatia, specialized structures on the undersides of leaves, appear to promote mutualism between plants and those mites that protect leaves from pathogenic fungi and small herbivorous arthropods. Their occurrence was surveyed on 425 plant species (368 native species and 57 species introduced from other regions of northeastern Asia), comprising 177 genera and 59 families of woody Dicotyledonae in the Korean flora. Domatia, primarily of tuft or pocket forms (84% of species), were present in vein axils on leaves of 152 species (36%) within 66 genera (37%) and 39 families (66%). Overall, we report leaf domatia in nine new families and 25 additional genera. Mites, primarily from families or suborders (e.g., Acaridida, Phytoseiidae, Tydeidae) in which arboreal representatives are primarily fungivorous or predaceous, were found in domatia on leaves of 78% of all species sampled. Domatia frequency depended upon both growth form and habit of species. They were especially common among tree species (55%), but less so on shrubs (20%) and woody vines (22%). Domatia were much more frequent on species of deciduous plants (40% of those sampled) than on evergreen species, of which only 10% had leaf domatia. This difference was consistent across a number of local deciduous and broadleaf evergreen forests in South Korea. The high frequency of leaf domatia in this survey indicates that plant-mite mutualism may be widespread in Korean plant communities. The floristic affinities of plants with domatia in Korea to those in other regions of East Asia, eastern North America, and Europe suggest that these plant-mite associations characterize the temperate broadleaf deciduous forest biome in the Northern Hemisphere.     

A late pleistocene and holocene vegetation and environmental record from Lake Wangoom, Western Plains of Victoria, Australia

Pollen, microfaunal and sedimentological evidence from the top 20 m of sediment in a closed volcanic crater lake is used to construct a detailed record of vegetation and environmental conditions through the Holocene and a substantial part of the Late Pleistocene. Radiocarbon dating suggests that the sequence covers tha last 51,000 yr or so. High lake-levels and the presence of forest or woodland vegetation indicate that the Holocene and the basal few thousand years of the record experienced wet and warm conditions. The earliest period was succeeded by a long phase of lower but variable moisture levels before more arid conditions resulted in the replacement of forest and woodland by herbaceous vegetation and frequent lake drying. Periods of slight amelioration occurred between about 27,000 and 19,000 and before 15,000 radiocarbon yr ago. Maximum aridity occurred between about 19,000 and 10,000 yr B.P., a period incorporating the height of the last glacial. During the Pleistocene, the lake became gradually more saline but has been fresh during the Holocene, even under low lake-levels.

An increase in charcoal values is recorded, probably around 20,000 years ago, and this could have resulted from increased burning as a result of the activities of Aboriginal people. This may have also caused a change in understorey vegetation from one composed largely of Asteraceae, to grassland.

The record is compared with others from southeastern Australia and there is good correspondence through the last 20,000 or 30,000 yr but, before this, problems of dating and the condensed nature of most sequences prevent detailed correlation.     

The composition,structure and distribution of heathland and grassland communities in the subalpine tract of the Bogong High Plains,Victoria

In the subalpine tract of the Bogong High Plains (37°S, 147°E; altitude 1600–1800 m a.s.l.) the vegetation consists of a mosaic of snow gum (Eucalyptus pauciflora) woodland, heathland, grassland and wetland communities. Classification (polythetic-agglomerative) and ordination (principal co-ordinates analysis) of quadrat data from heathlands and grasslands on relatively well drained sites allowed the identification of four main heathland and grassland vegetation units. These units may be ranked in a structural and floristic continuum, from closed heath variously dominated by Prostanthera cuneata, Orites lancifolia and Phebalium squamulosum to closed heath dominated by P. squamulosum and Grevillea australis, open grassy heath of G. australis and Poa hiemata. and grassland of P. hiemata. The transition from Prostanthera closed heath to Poa grassland is correlated with gradients of decreasing steepness and rockiness of terrain, and increasing exposure and frost.     

The seedbanks of the Breckland heaths and heath grasslands, eastern England, and their relationship to the vegetation and the effects of management

The vegetation and the associated germinable seedbank of a range of heath and grass heath communities in Breckland, eastern England, were compared. The composition of vegetation and seedbank were similar for heather-dominated communities due to the predominance of Calluna vulgaris . Recent rotovation of previously heather-dominated communities invaded by Deschampsia flexuosa reduced the number of emerging C. vulgaris seedlings by more than 80%. The composition of seedbanks of calcicolous grasslands differed considerably from the vegetation, with a significant contribution from many ruderal species not present in the vegetation and an absence of important species such as Pilosella officinarum. Acidic grasslands were intermediate between calcicolous grasslands and heather-dominated heathlands, with seedbanks characterized by high densities of Rumex acetosella and a number of ruderal species that were absent or rare in the vegetation. The composition of the seedbank of more mesotrophic grasslands suggests that the imposition of some form of disturbance may recreate more open grasslands typical of Breckland.     

围封对草地的影响研究进展

围封是草地管理的重要手段.围封通过排除家畜的践踏、采食及排便等干扰,从而使其群落向着一定方向演替.由于草地生态系统本身的复杂性和放牧历史、环境因子等的迭加作用导致退化草地群落围封后出现3种可能的演替模式,即单稳态模式、多稳态模式和滞后模式.由于围封后种群的消长、某些种群的消失及新种的进入导致草地在围封后的植物多样性也发生变化.从"中度干扰"理论、对放牧敏感性植物种消失、以及特殊环境因子下群落恢复缓慢等方面总结了草地围封后植物多样性的3种可能变化方向.总结了围封对土壤种子库的影响及其在草地恢复中的作用.阐述了围封对草地土壤理化性质的作用机制.总之,围封对草地的作用具有两面性.对围封作用要有全面的科学认识,把握好围封的时间尺度,以充分发挥其在退化草地恢复中的作用,避免由于利用不当而对草地产生的负面影响.建议加强对已有相关研究成果的总结与分析,对不明确和有争议的课题进一步深入研究,并建立长期的围封研究项目,增加围封研究的站点建设.     

Long-term effects of grazing on subalpine and alpine grasslands in the Central Alps,Austria

The effects of grazing exclusion on species diversity and functional diversity were analyzed along an elevation gradient from the subalpine (1960 m a.s.l.) to the lower and upper alpine zone (2275 m–2650 m a.s.l.) in the Austrian Central Alps for 15 years. Nine sites were chosen, including grasslands at different elevations, a bog and a glacier foreland site at the lower alpine zone and a snowbed at the upper alpine zone. Data were acquired by frequency counts in 1 m² permanent plots inside each fenced area (three plots per site) and outside in grazed areas (three plots). Diversity indices and functional diversity were analyzed by means of generalized linear mixed models (GLMMs). Exclosure, duration of exclusion and exclosure*years (interaction effect) were defined as predictor variables. Multivariate ordination techniques were used to (i) determine species responses to grazing exclusion (pRDA, partial redundancy analysis) and (ii) to create a distance matrix representing the changes between exclosures and control plots per year (NMDS, non-metric multidimensional scaling). At the subalpine grassland, first differences between exclosure and control plots occurred already only after three years, at the upper alpine zone after four and five years. Contrary to our expectation, dwarf shrubs did not increase within the exclosures of the subalpine grassland. Instead, mainly the tall forb Geranium sylvaticum increased. Species richness significantly decreased at the exclosures of the subalpine zone, the snowbed and at one upper alpine grassland sites. The communities of the glacier foreland and the bog were hardly affected by grazing exclusion.We conclude that plant species and communities react individually depending on elevation and grazing animals. Grazing exclusion studies at high elevations should definitely be carried out in the long-term.     

Restoring Western (Basalt) Plains grassland. 2. Field emergence, establishment and recruitment following direct seeding

Summary   Both reservation of small remnants and ecological restoration of degraded areas will be crucial if the Victorian Western (Basalt) Plains grassland community is to be conserved in the long term. This study examined the potential of direct seeding as a technique for grassland restoration by recording the initial establishment and subsequent recruitment success of 64 (predominantly perennial) grassland species direct sown onto a constructed site. Forty-three (67%) of the sown species emerged and established during the 2-year study and a further three species were recorded in subsequent years. In the second year, 32 species increased their number either through seedling or vegetative recruitment and 30 species dispersed beyond their original sown plot. Seed size was not correlated with field emergence but life form did influence initial field success for some groups. The finding that many species are able to establish and recruit under the study conditions supports the need for further investigation of direct seeding in the restoration of grassland communities.     

Comparison of butterfly communities and abundances between marginal grasslands and conservation lands in the eastern Great Plains

The alteration and fragmentation of native tallgrass prairie in the Midwestern United States has created a need to identify other land types with the ability to support grassland butterfly species. This study examines butterfly usage of marginal grasslands, which consist of semi-natural grasslands existing within in a larger agricultural matrix, compared to grasslands managed for conservation of prairie species. Using generalized linear mixed models we analyzed how land purpose (marginal vs. conservation grasslands) affected butterfly abundance. We found grassland butterfly species to be significantly more common on conservation grasslands, whereas generalist species were significantly more common on marginal grasslands. Results of ordination analyses indicated that while many species used both types of habitats, butterfly species assemblages were distinct between habitat types and that edge to interior ratio and the floristic quality index of sites were important habitat characteristics driving this distinction. Within conservation grasslands we examined the relationship between butterfly abundance and the planting diversity used in restoring each site. We found higher diversity restorations hosted more individuals of butterflies considered habitat generalists, as well as species considered to be of conservation concern.