Grassy Communities Research Articles

Native establishment improved and weed competition reduced by topsoil removal in direct‐sown native grasslands

SummaryAustralian temperate grasslands are among its most threatened plant communities. In agricultural landscapes, major barriers to their recovery are high soil nutrient levels that favour the growth of exotic pasture and other non‐native species, high standing weed biomass creating fierce aboveground competition, and rich weed seed and bud banks providing dense emergent seedling competition. Therefore, the return of grasslands to arable landscapes through restoration must rely on overcoming these challenges, ideally by reducing soil nutrients and mitigating the effects of weeds. This study demonstrates the effectiveness of topsoil removal for restoring diverse native grassy communities by direct seeding on sites with a legacy of elevated soil nutrients and competitive exotic vegetation. Conversely, it showed that repeated shallow cultivation (four times over 12 months) to stimulate weed emergence, followed each time by herbicide application, failed to achieve this outcome, at least in the short term (three years). Grassy community restoration is imperative in Australia, but importantly, it must utilise restoration protocols that are as effective as possible so that limited time, money, and resources are not wasted. In this light, the technique of topsoil manipulation may take us one step closer to achieving this goal in agricultural locations, where their loss is most pronounced.

Rational use of forest land honey reserve for honey collection of the Toratau geopark of the Republic of Bashkortostan

Besides obtaining valuable beekeeping products, bee families have a positive effect when pollinating forest plants, ensuring both high productivity of resources and promoting the conservation and favourable development of natural populations of forest species. The object of the study, the lands of the forest fund of the Toratau geopark of the Republic of Bashkortostan, serve as an optimization of the number, expansion of the range and maintaining the genetic purity of the population of the indigenous Burzyan side bee (Apis mellifera L). There needs to be more information on the inventory of honey resources on the territory of the Geopark. Therefore, the goal was to determine the honey stock of forest land for productive medical collection and rational use of resources. As a result of research, land with an area of 479,640 hectares was covered with forest, which includes significant territories of linden stands (213335 hectares - 44.5%) and broad-leaved forest that does not have nectarines of linden and maple (194924 ha - 40.6%). Lipnyak is characterized by a biological resource potential of 96117283.3 kg and a broad-leaved forest, respectively, 904447.36 kg. The total estimated honey reserve of the territory of the Republic of Belarus mountain-forest zone consists of 104 595 108 kg, which will allow for keeping up to 560,704 bee families. Small-leaved linden accounts for 89.3%, located extremely unevenly in the studied territory. In the years favourable for the production of linden, the organization of nomadic beekeeping is necessary. The share of nectar reserves of maple, willow and grassy communities relative to but is small and amounts to 9.6%. However, given the instability of colour and nectar release of linden, the presence of alternative sources of nectar allows the preservation of the number of stationary bee families in the “lean years.”

Изменения структуры и биоразнообразия лиственничных лесов в верхнем течении р. Хилок (бассейн оз. Байкал) под воздействием пожаров

The study results of changes in the larch forests’ structure and biodiversity in the upper Khilok River basin (right tributary of the Selenga River) affected by the climate change and forest fires in the period from 1996 to 2018 are presented. It was found that the area of closed forests decreased by an average of 51 %, the burnt forest area and burnt timber increased by 46%, dwarf birches decreased by 12 %, the natural reforestation of the sample areas is 90 % poor and unsatisfactory. It was revealed that due to fires in forest communities, the total number of plant species and lichens decreases, indices of species wealth and biodiversity concentration decrease in plant communities, and the ratio of species of latitudinal geographical groups (forest, steppe and meadow) changes. It is shown that with further climate aridization, an increase in the area of dwarf birches communities after fires can lead to the replacement of forests with shrubby, and later grassy communities. It is recommended to continue research on changes in the structure and biological diversity of plant communities in the selected model areas due to an increase in the amount of spring-summer precipitation in the region.

Understanding patterns and pathways of exotic perennial grass invasion in South‐eastern Australian grassy communities

AbstractAimExotic perennial grasses (EPGs) are significant invaders of native grassy communities. We sought to determine how the profile of invading perennial grasses varies among different climatic regions and different grassy communities, to understand at which scale management is best undertaken. We investigated whether invader occurrence was related to specific plant traits.LocationNew South Wales, Australia.MethodField surveys of EPGs at 139 sites from nine grassy communities across four regions were assessed for variation in invasion profiles amongst regions and communities. We used a ranking of invasion risk based on plant characteristics to identify grasses likely to be more invasive and tested whether this ranking predicted the level of invasion in the survey.ResultsUsing multivariate analysis, we found that all communities were significantly invaded. These assemblages were distinct regionally, and for most plant communities. Five widespread invaders were established in all regions and communities. Invasion by pasture grasses (termed trade‐off species) was the most significant threat, coupled with capacity to develop long‐term seed banks and use allelopathy. Species with higher risk rankings were recorded in more sites, although a few grasses had much greater occurrences than their ranking predicted.ConclusionsGrassy communities across all regions were invaded by a suite of EPGs, some that have not been considered as problematic previously. Higher levels of invasion were associated with higher ranked species based on plant traits, indicating that our risk assessment is valuable as a management prioritization tool. Findings support community level management, although some species are important widespread invaders and could be managed at larger scales. Differences in species assemblages compared to nearby agricultural areas confirm different invasion pathways, with significant invasion from pasture grasses. Aided by the risk assessment tool, we propose that EPG management in native communities considers the climatic, community (including surrounding) and species level for prioritization.

Natural and anthropogenic extensive destruction of the spruce forest community of the European part of Russia: main trends of biodiversity dynamics

We analyzed the main trends of the change in the species richness of plant communities after catastrophic natural (beetle outbreaks, windfalls) and anthropogenic (clear cutting) disturbances. We examined the dynamics of the structural diversity of species richness of herb-dwarf scrubs layer with different reforestation technologies after the death of spruce stands. The study of similarity and ordination of vegetation showed the proximity of the undamaged forest to the unharvested stand, and the difference of these plant communities from clear-cut. The main determining factor of species richness was the intensity of plant community disturbance after catastrophes. We analyzed the reforestation dynamics of plant communities after catastrophic disturbances. Clear cutting led to the formation of grassy communities with a sharp increase in the species and structural diversity of plant community.

IDENTIFYING UPPER MIOCENE – LOWER PLIOCENE LACUSTRINE SEDIMENTS IN DRY TUNKA BASIN OF THE BAIKAL RIFT ZONE

We present results of lithogeochemical, diatomic and palynological studies of sediments from the Tunka-13 well that was drilled in the southeastern part of dry Tunka basin in the Baikal rift zone. At the base of the section, there is an eroded basaltic flow of 16–15 Ma. From lithogeochemical signatures, we identify nine sedimentary units. The seven lower ones (interval 7.2–86.5 m) belong to the Tankhoi formation, the eighth (interval 2.7–6.6 m) to the Anosov formation, the ninth (interval <2.4 m) to the sandy stratum. We determined local sources of clastic material of basaltic and silicic compositions for units 1 and 2, respectively, and remote sources of silicic compositions for the overlaying units. The section shows a change from alluvial facies (units 1–3) through avandelta (unit 4) and lacustrine ones (units 5–7), again to alluvial facies (unit 8) and then to lacustrine-eolian ones (unit 9). Spore and pollen spectra from sediments of units 1–7 are divided into three palynozones (PZ), reflecting the vegetation change in the Late Miocene – Early Pliocene: PZ-1 – coniferous and deciduous forests with a small participation of thermophilic broadleaved species in moderately warm, humid climatic conditions; PZ-2 – enhancing the role of hemlock and more diverse thermophilic deciduous rocks in more humid and warm conditions; PZ-3 – a gradual reduction in the number of hemlock and other dark coniferous species, removing broad-leaved species by birch and alder, growing grassy communities in wetlands due to climate cooling. We identified layers of lacustrine facies by occurrence of fossil diatoms that are absent in the layers of the alluvial and avandelta facies. In lacustrine sediments, we distinguish four diatom zones: DZ-1 denotes a relatively deep Late Miocene paleolake, marked by planktonic species, DZ-2, DZ-3 and DZ-4 – a shallow Early Pliocene lake with a developed littoral zone and short transgression. The Late-Miocene paleolake transgression, indicated by changing facies, is associated with structural reorganization, accompanied by volcanic extinction in the Tunka valley about 9–8 Ma, and the Early Pliocene short transgression with a new reorganization, reflected in volcanic rejuvenation about 4.0 Ma.

On the problem of preservation of inundated ecosystems of the planet

In article the question of value of inundated ecosystems of the planet for the biosphere, importance of preservation of their steady state in the conditions of the escalating pressure of an anthropogenic factor is considered. Authors within several years made monitoring of the vegetable communities of the floodplain of the Yutsa River subject to pollution by an unauthorized dump of solid household and construction waste. Change of a specific variety of grassy communities of the studied territory subject to anthropogenic influence has been as a result registered. The group of the plants which are most adapted (tolerant) for observed changes of the surrounding environment which is probably the so-called destructive link which is a basis for the subsequent restoration of the studied grassy community in these changed conditions is found. It is revealed that the changes in the specific structure of vegetable community which have led to loss of stability of the damaged territory continued some time and after elimination of anthropogenic influence, becoming populated by invasive types.

A Model of Vegetation Cover in Conditions of Resource Scarcity: Fairy Rings in Namibia

A mosaic of barren grounds (bars) and areas covered by vegetation often forms in grassy or shrubby communities in conditions of scarcity of environmental resources (e.g., water). Such landscapes have been named “two-phase mosaics”; this term emphasizes the discreteness of vegetation cover units. Fairy rings (FRs) are an example of such structures. There are two sets of competing hypotheses on the reasons behind FR formation: insect activity and self-organization. One of the main arguments against the second set of hypotheses is their inability to explain the FR life cycle: their emergence, ripening, maturation, and disappearance (death). The article proposes a simple cellular-automaton model of the vegetation cover formation. The model imitates the scarcity of resources (water and ash constituents) and generates different variants of the two-phase mosaic. The results depend on two parameters: limitation of resource inflow and plant growth rate. Sixteen percent of combinations of these parameters result in the formation of structures similar to FRs. The model reproduces not only the vegetation distribution pattern observed in the nature but also individual FR life cycles that are consistent with field descriptions. Thus, the model removes the main objection to self-organization as the main mechanism of FR formation.

Noah's Ark conservation will not preserve threatened ecological communities under climate change.

BackgroundEffective conservation of threatened ecological communities requires knowledge of where climatically suitable habitat is likely to persist into the future. We use the critically endangered Lowland Grassland community of Tasmania, Australia as a case study to identify options for management in cases where future climatic conditions become unsuitable for the current threatened community.MethodsWe model current and future climatic suitability for the Lowland Themeda and the Lowland Poa Grassland communities, which make up the listed ecological community. We also model climatic suitability for the structurally dominant grass species of these communities, and for closely related grassland and woodland communities. We use a dynamically downscaled regional climate model derived from six CMIP3 global climate models, under the A2 SRES emissions scenario.ResultsAll model projections showed a large reduction in climatically suitable area by mid-century. Outcomes are slightly better if closely related grassy communities are considered, but the extent of suitable area is still substantially reduced. Only small areas within the current distribution are projected to remain climatically suitable by the end of the century, and very little of that area is currently in good condition.ConclusionsAs the climate becomes less suitable, a gradual change in the species composition, structure and habitat quality of the grassland communities is likely. Conservation management will need to focus on maintaining diversity, structure and function, rather than attempting to preserve current species composition. Options for achieving this include managing related grassland types to maintain grassland species at the landscape-scale, and maximising the resilience of grasslands by reducing further fragmentation, weed invasion and stress from other land uses, while accepting that change is inevitable. Attempting to maintain the status quo by conserving the current structure and composition of Lowland Grassland communities is unlikely to be a viable management option in the long term.

Changes tropical monsoon higt-stem forests in the Vietnam

Tropical ecosystems are the major component of the biosphere rendering global influence to atmospheric conditions on our Planet and determining it well-being. Tropical forest communities are the most difficultly organized and rich of animal and plant species biological systems with internal cyclic of metabolism and regenerative processes. On a background of growing human intensification of tropical forest resources using profound and deep researches, understanding, monitoring and prognostic of reactions of tropical primary forest ecosystems on external and internal impact and destruction are represented extremely urgent now. Vietnam monsoon tropical forests are very ancient and evolutionary vegetative formations. A species composition of the tropical forests includes not less than 7000 plant species, from which more than 3000 species - trees. The greatest variety of plant species and complex vertical structure are characterizing for high-stem tropical forests. Tropical forest ecosystems represents the climatic climax and ones are in dynamic balance. This balance is determined internal and external infringements, evolutionally characteristic for these plant communities. For monsoon primary forests, natural kinds of tree canopy destructions are different forest gaps, which form as a result of fall down whole trees, break tree trunks, crowns or branches. Such phenomena as a burning or fire is not characterize for these forests. Strong storms are quiet rare events too. Forests in mountain there is a gravitation movement of a soft soil substratum or a solyphluction (landslide) is adding to gaps. Inside forest gap there is a change of a microclimate in a direction increasing insulation, temperatures of air and soil. A reforestation on gaps goes due to realization of adaptive abilities of forest trees and lianas with the minimal participation of pioneer plants. A restoration of the primary forest structure and plant species composition may be named like a demutate succession. Uses by the man for agriculture a small forest area (up to 2-4 ha) can be considered as the external factor initiating demutate succession process. However, a Man also is carrying into a tropical nature life such global destructions as cutting down and clearing on forest areas for fields and plantations and apotheosis of human destruction - military destruction forests by herbicide spraying, napalm and fire bombs during The Second Indochina war. Our research in primary and human-transformed tropical forest ecosystems in Southern, Central and Northern Vietnam has shown that forest reactions to human intervention are very specific. Reactions are determined by a complex of factors, in particular the species composition of plants, spatial structure of the forest community, presence of the main forest species of trees, phenology and physiology of forest plants, features of forest microclimate, relief, structure of the soil and its hydrology. The district Linh Thuong in province Quang Tri (Central Vietnam) - is one of the most destroyed during the War. To the present time, after more than thirty years after War grasslands, which were appeared on the place primary forests, have not undergone changes in the party of change by their tree or bush communities. Our researches in this area are proved. That, the occurrence not forest open territories has resulted in change of a microclimate, hydrological regime, properties of soil and development of erosive processes. So, in July - a most hot month - the day time temperatures of air under the forests canopy (on a point 120 cm above a surface of the ground) reached 33oC, whereas on grasslands the maximal meaning was 43oC. The temperature of a ground surface under the forest canopy rose up to 28oC, whereas on grasslands maximum was 36oC. The humidity of air under the forests canopy changed from 85 up to 100%, on grasslands - from 55 up to 95%. So, in result of the military influence to primary forests have appeared atonal savanna-like grassy communities. The complex and multi-species forest communities were replaced for the simple and mono-species communities. The main forest tree species and pioneer trees, by virtue of their biological features and changes of microclimate, are not adapted to growth and development on these territories. The global human destructions are occurred a reason of interruption successions in the forest ecosystems. The existence of such grassy communities is uncertainly long, since there are no factors - except a human factor, - capable to change a trend of their development. Using of these grassy areas for agricultural cultivation or planting forest cultures will be demanded the special scientific knowledge for development of competent and ecologically responsible technological receptions on a background of an investment of significant financial means.

Trade‐offs in resource allocation that favour resprouting affect the competitive ability of woody seedlings in grassy communities

Summary 1. Differences in the competitive ability of plant functional groups at early life‐history stages can have important consequences for community structure. In particular, trade‐offs in allocation to roots by woody plant seedlings may influence competitive ability with grasses in fire‐prone vegetation. 2. We followed post‐fire survival of seedlings of facultative resprouter and obligate seeder (fire‐killed) shrubs for 3 years in adjacent communities with a grassy/graminoid ground stratum (54 plots, 20 m2) or a non‐graminoid ground stratum (54 plots, 20 m2). 3. The competitive effect of a grass (Poa) on seedlings of three congeneric pairs of resprouters and obligate seeder shrubs was tested in a factorial experiment where nutrients and the grass competitor were manipulated. The effects of grass (+,−) and nutrients (+,−) on the growth response, biomass allocation and root carbohydrate storage were measured after harvest at 26 weeks and the relative neighbour effect calculated. 4. Post‐fire shrub seedling survival was high with about 50% (2163 seedlings) surviving over 3 years, but this varied between habitats and functional groups. In the grassy/graminoid ground layer communities 27% of shrub seedlings survived, whereas in the habitats with a more open ground stratum 55% of seedlings survived. In grassy habitats, obligate seeder survival was lower (23% survival) than that of resprouter seedlings (35% survival). Similarly, in open habitats, obligate seeder seedling survival was lower (51%) than that of resprouter seedlings (64% survival). 5. Growth of both resprouters and obligate seeders in our manipulative experiment was strongly reduced in the presence of a grass competitor. Moreover, the addition of nutrients increased the relative difference in mass and height between those seedlings exposed to a grass competitor and those grown without a competitor. Resprouter species allocated more to roots under competition and were less affected by grass competition than obligate seeders. 6. Synthesis. The results of seedling survival and of the experiment on the effects of grass competition on woody plant seedlings suggest that early life‐history trade‐offs in allocation influence seedling survival. Allocation to resprouting appears to enhance the ability of shrub seedlings to survive grass competition. We propose that grass competition across productivity gradients plays an important role in influencing landscape‐level distribution patterns of woody resprouters.

Spatial and temporal patterns of recent forest encroachment in montane grasslands of the Valles Caldera, New Mexico, USA

AbstractAim Recent forest encroachment into montane and subalpine grasslands has occurred in the Rocky Mountains and many other mountain ranges globally. The timing, rate, and extent of tree invasion can depend on interactions among topography, positive spatial feedbacks, and temporally variable factors (especially climate, grazing, and fire). Here we examine spatial and temporal patterns of tree invasion in the Valles Caldera of the Jemez Mountains.Location This study was conducted in the Valles Caldera (35°50′–36°00′ N; 106°24′–106°37′ W), a 24‐km‐wide volcanic basin in northern New Mexico, USA. Grasslands in this otherwise forested region occur in broad valley bottoms of the caldera floor between 2575 and 2700 m, and on south‐facing slopes and mountain tops up to 3300 m.Methods We used a GIS analysis of orthorectified aerial photos taken in 1935 and 1996, covering a 40,000‐ha study area, to quantify the extent of tree invasion and to assess its relationship to spatial factors. We obtained dates of establishment from 299 increment cores and basal disks from 50 sites in the Valles Caldera National Preserve (VCNP) to reconstruct temporal patterns of tree invasion.Results The area of grasslands in our study area declined from 11,747 to 9336 ha (nearly 18%) between 1935 and 1996. Tree invasion increased with slope, elevation, and proximity to the previous tree line, but showed no relationship to aspect. Tree invasion was more rapid and continuous on upper mountain slopes, while the invasion of valley‐bottom grasslands below reversed tree lines was more episodic, and appeared to track mean summer minimum temperatures.Main conclusions The rapid and continuous invasion of steep, high‐elevation slopes suggests that frequent fire was the single most important factor in maintaining grassy communities in these sites. The slower, episodic invasion of valley‐bottom grasslands, and the apparent relationship between increased invasion and years of higher summer minimum temperatures are consistent with the hypothesis that these grasslands have been maintained by low temperatures or frosts damaging to tree seedlings. We encourage prescribed fire to restore and maintain grasslands in the VCNP, especially small patches on steep, high‐elevation slopes.

Mapping Prairie Pothole Communities with Multitemporal Ikonos Satellite Imagery

We evaluated the ability of Ikonos imagery from August and October 2000 to classify prairie pothole community types of the Missouri Coteau of North Dakota. Classification tree analyses were conducted to create land-cover maps at three levels of detail. The analyses successfully distinguished broad cover types (potholes including emergent vegetation versus upland vegetation) at 92 percent overall accuracy. Overall accuracy dropped to 80 percent when upland vegetation was segregated into woody and grassy communities and to 71 percent when we attempted to classify at the species or near-species levels. The use of two image dates was of importance in the classifications; the failure to acquire early season imagery, therefore, might have impaired our results.

Emergence and survival of herbaceous seedlings in temperate grassy woodlands: Recruitment limitations and regeneration niche

Abstract Field experiments examined herbaceous seedling emergence and survival in temperate grassy woodlands on the New England Tablelands of New South Wales. Effects of intensity of previous grazing, removal of ground cover by fire or clearing, burial of seeds, grazing and seed theft by ants on seedling emergence and survival were studied in two field experiments. Thirteen species with a range of traits were used in the experiments and their cumulative emergence was compared with laboratory germination studies. Field emergence correlated to laboratory germination but all species had lower emergence in the field. Little natural emergence of native species was observed in the field in unsown treatments. Short‐lived forbs had the highest emergence, followed by perennial grasses; rhizomatous graminoids and perennial forbs had the lowest emergence. Soil surface and cover treatments did not markedly enhance emergence suggesting that intertussock spaces were not prerequisites for forb emergence. No consistent pattern of enhanced emergence was found for any treatment combination across all species. Seedling survival varied among species, with perennial grasses and short‐lived forbs having the highest seedling mortality. Low mortality rates in the graminoids and rhizomatous forbs appeared partially to compensate for lower seedling emergence. All perennial grasses and some short‐lived forbs showed increased risk of mortality with grazing. Differences in emergence and survival of species were related to ground cover heterogeneity, soil surfaces and, to some extent, herbivory. The complexity of these patterns when superimposed on temporal variability suggests that no generalizations can be made about the regeneration niche of herbaceous species groups. Strong recruitment limitation and partitioning of resources in the regeneration niche may reduce competition among native species and explain the high species richness of the herbaceous layer in the temperate grassy communities of eastern Australia.

Potential impacts of fire and grazing in an endangered ecological community: plant composition and shrub and eucalypt regeneration in Cumberland Plain Woodland

Exclosure plots were used to determine the effect of fire and grazing on the structure of a grassy-woodland community. Eighteen months after fire and fence treatments were applied, the species richness, cover and composition of shrubs, trees, herbs and grasses were assessed and compared to pre-treatment censuses. Unburned plots had fewer shrub species and a lower abundance of shrubs, indicating the importance of fire in promoting regeneration of shrub species. Eucalypt species were more abundant and richer following the wildfire burn in summer, suggesting timing of fires is an important aspect in the establishment of the canopy species. Interactions between fire and grazing were found for the abundance of eucalypts (although weak) and resprouting eucalypts, suggesting a subtle interaction between fire and grazing shortly after fire. There was no effect of grazing and no interaction effect between fire and grazing on shrub species richness and abundance or tree species richness and seedling abundance.All plots showed a change in species composition despite treatment, and 46 species (32% of total richness) were recorded only in the final survey. The high rainfall during the 18-month study is likely to be an important factor in facilitating the establishment of species following all disturbances. This may have ameliorated the impact of grazing as abundant food was available throughout the woodland. The interaction between fire and grazing may be more important in structuring these grassy communities during periods of lower rainfall.

The role of small ground‐foraging mammals in topsoil health and biodiversity: Implications to management and restoration

Summary Many early Australian records indicate that at the time of European settlement there were extensive tracts of highly productive, and species‐rich, grassy communities and chenopod shrublands. Topsoils in many areas were soft and friable. The rapid development of livestock industries led to most changes to the environment being simplistically ascribed to domestic stock grazing, land clearance, introduced pests (such as rabbits) or changed burning practices. It has also commonly been assumed that the hoof action of domestic stock was the principal cause of the compaction and surface sealing of soils in many areas. However, the rapid soil deterioration also coincided with the dramatic decline or complete extinction of many small native ground‐foraging mammals and the consequent cessation of the soil disturbances and interactions that they created. This paper reviews the role of small mammals in disturbing soils, and implications for incorporation of organic matter, aeration, improvement in infiltration and the provision of suitable sites for seed germination and seedling establishment. This can aid topsoil formation and health by providing substrate for microorganisms, improved water balance and mineral cycles and enhanced soil structure. Seeds and mycorrhizal fungi, that are integral to the establishment and growth of many plants, are spread. Such intermittent disturbance may be an important driving force in determining the pathway of succession and lead to greater biodiversity. Further ongoing research on Australia's small mammals is needed, especially in areas where they are able to move freely in a natural environment and are protected from introduced predators.

Grazing response groups among understorey plants in arid rangelands

Abstract.We analysed attributes of the understorey flora in different plant communities along two grazing gradients in arid Australian rangelands. We aimed to determine if there were patterns among species in response to grazing, and easily recognizable ‘indicator response types’ for monitoring grazing‐induced change in community composition. Measurements were stratified by vegetation patch type, in woody groves and open patches. Trait selection and analyses followed a hierarchical approach which searched for patterns within major plant life forms. Patch type exerted a dominant influence on both life forms and species attributes, but interacted with grazing. Grazing was associated with loss in differentiation of species composition between patch types, rather than loss in numbers of species overall. Heavy grazing was variously associated with small size, prostrate habit, low meristems, small leaves, coated leaves, high regrowth potential, plasticity in response to grazing, and high fecundity; and light grazing with opposing attributes. Many attributes tended to vary independently of each other and grazing‐related attribute syndromes were recognisable only among grasses. This could be because the environmental filters acting on the communities have given rise to many different species with different natural attribute combinations, few of which are closely associated with grazing resistance. For grassy communities ‘large, erect tussocks branching above‐ground’ and ‘small, sprawling basal tussocks’ may have potential as response types indicative of light and heavy grazing respectively, but no response types could be identified for herbaceous communities.

Natural Grassy Vegetation and Native Forbs in Temperate Australia: Structure, Dynamics and Life-Histories

This paper describes aspects of the structure, floristics and dynamics of natural grassy vegetation in temperate Australia. The community structure of this vegetation type can be conceptualised using a matrix-interstitium model which may be useful in studies of the dynamics of forb populations and the role of disturbances in grassland management. Disturbance alters the balance between the matrix and interstitial components and is important for herbaceous communities as an agent in changes to, and losses of, native species. Life history characteristics conferring tolerance of disturbance upon native forbs are discussed, and the ruderal nature of the exotic component is suggested as a characteristic leading to the replacement of native forbs by exotic species, where substantial exogenous disturbance occurs. Despite the demonstrated importance of exogenous disturbances in influencing native species diversity and exotic invasions, there is still a poor understanding of the specific and interactive effects of various disturbances and the roles of particular plant traits in determining forb survival. Further research, utilising comparative or functional group approaches, is required to explain responses of natural grassy communities and native forbs. Such studies would provide opportunities for developing ecological theory and improving the management of natural grassy communities and their native forbs.

Life-History Attributes of Plants in Grazed and Ungrazed Grasslands on the Northern Tablelands of New South Wales

The composition, diversity and structure of unfertilised temperate grassy communities were compared, after adjacent areas had been grazed or left ungrazed for 16 years. Life-history attributes of species in the two communities were also compared. Most species in both treatments were forbs, but these generally occurred with low frequencies and grasses formed the vegetation matrix. Native and perennial species predominated, reflecting pre-European conditions. Long-term, continuous grazing by sheep had opened the grass and litter canopy, promoted species richness and favoured a suite of morphological plant characteristics. Thus, species with dormant meristematic tissue at or below ground level, forbs of low stature and small tufted grasses were relatively common. The ungrazed treatment was densely vegetated, relatively species-poor and plants tended to have morphological attributes opposite to the above. A later, double-peaked flowering period in the ungrazed community was explained by the greater proportion of native perennials, versus the more common early-flowering exotic annuals in the grazed community. The larger proportion of vegetatively reproducing forbs in the ungrazed treatment reflected the density of the vegetation and the possible absence of appropriate sites for regeneration by seed, or the heterogenous distribution of resources available to interstitial plants.

The genus Betula in Greenland‐Holocene history, present distribution and synecology

After its arrival in E Greenland c. 8000 C‐14 years B.P.Betula nanaspread rapidly to become a dominant plant. A climatic change c. 5000 B.P. almost exterminated it at more oceanic sites, whereas inland it only lost little ground. Today it is common inland in many kinds of heath and other vegetation types. When it spread to Middle W Greenland around 6500 B.P. it only took two to three centuries to become dominating in the continental inland whereas the spreading to the coastal areas began later and was more gradual. After the Holocene climatic optimum it decreased here but kept its dominating position inland, where today it is a main plant in mossy heaths on N slopes and dry, grassy communities on S slopes.Betula glandulosaarrived in SW Greenland c. 5 700 B.P., later on in S Greenland. It is a lowarctic, oceanic plant, missing only on the outer skerries, but being common in mossy heaths all through the fjords, where it also occurs in grassland vegetation types and, at the head of the fjords, as undergrowth in the subarctic, usually 4–5 m high birch woodlands formed byB. pubescens, which did not arrive until c. 3500 B.P. The most common plant communities, in which the threeBetulaspecies occur in different parts of Greenland are summarized, partly by referring to other publications, partly by presenting six new tables of vegetation analyses, stored in the Botanical Museum or published in “grey literature”. Where the species meet, hybridizing and introgression take place. Distribution maps of the three species and two hybrids are presented, and the taxonomy summarized.