Sparse Ground Cover Research Articles

The topographic threshold of gully erosion and contributing factors

The topographic threshold is based on the power relationship between area and slope and is widely applied in gully-erosion research; however, this relationship requires further testing. Accordingly, the Alamarvdasht Lamerd and Fadagh Larestan regions in Fars Province, Iran, were selected as case studies to explore the topographic threshold for gullies. Thirty active gullies were identified in each study area during field surveys, and data describing land use and land cover, drainage areas, slope, and the physical and chemical properties of the soils were assembled. Multivariate analysis was conducted using SPSS to determine the effects of these factors. Using the power relationship between the catchment area and slope for each gully, the analyses explored critical controls for gully development. The results showed that surface runoff was the most significant effective factor for gullies in the study areas. Sparse ground cover, fine-textured soils, and inappropriate land use contribute to gully development. The results suggest that the relationship between slope and drainage area in the Fadagh Larestan case study is S = 0.0192 A−0.159 for gully headcut areas and S = 0.0181 A−0.258 at gully outlets. The corresponding values of the exponent β at the gully headcuts and outlets at Fadagh were − 0.15, and −0.25, respectively. The corresponding relationships for gullies in the Alamarvdasht Lamerd area for the gully headcuts and outlets were S = 0.0143 A− 0.061 and S = 0.0073 A−0. 18, respectively, with β values of − 0.06 and − 0.18. This study provides a basis for determining the thresholds for initiating gully development. Analyses of the effective factors provide clues to improve the management of bare lands to prevent the initiation of gully erosion.

Conservation of endangered Tipton kangaroo rats (Dipodomys nitratoides nitratoides): status surveys, habitat suitability, and conservation recommendations

The Tipton kangaroo rat (Dipodomys nitratoides nitratoides; TKR) is listed as endangered both Federally and by the state of California due to profound habitat loss throughout its range in the southern San Joaquin Valley of California. Habitat loss is still occurring and critical needs for TKR include identifying occupied sites, quantifying optimal habitat conditions, and conserving habitat. Our objectives were to (1) conduct surveys to identify sites where TKR were extant, (2) assess habitat attributes on all survey sites, (3) generate a GIS-based model of TKR habitat suitability, (4) use the model to determine the quantity and quality of remaining TKR habitat, and (5) use these results to develop conservation recommendations. We surveyed for TKR on 44 sites by live-trapping and detected TKR on 15 sites. Sites with TKR tended to have larger alkali scalds and no obvious sign of past tilling compared to sites without TKR. Also, sites with TKR usually had relatively sparse ground cover and seepweed (Suaeda nigra) was present. The non-protected Heermann’s kangaroo rat (Dipodomys heermanni), a larger competitor, was either absent or present in relatively low numbers at sites with TKR, and when present its abundance was inversely related to that of TKR. Based on our habitat suitability modeling, an estimated 30,000 ha of moderately high or high quality TKR habitat and 60,000 ha of lower or medium quality habitat remain. However, habitat is still being lost and conversion of at least one survey site with TKR occurred during this project. Recommendations for TKR conservation are to (1) conduct additional TKR surveys on unsurveyed but suitable sites, (2) conserve suitable habitat on unprotected lands, (3) manage vegetation on occupied sites if necessary, (4) restore disturbed lands to increase suitability for TKR, and (5) research methods and conduct translocations of TKR to unoccupied sites with suitable habitat.

Conservation of threatened San Joaquin antelope squirrels: distribution surveys, habitat suitability, and conservation recommendations

The San Joaquin antelope squirrel (Ammospermophilus nelsoni: SJAS) is listed as Threatened pursuant to the California Endangered Species Act due to profound habitat loss throughout its range in the San Joaquin Desert in California. Habitat loss is still occurring and critical needs for SJAS include identifying occupied sites, quantifying optimal habitat conditions, and conserving habitat. Our objectives were to (1) conduct surveys to identify sites where SJAS were present, (2) assess habitat attributes on all survey sites, (3) generate a GIS-based model of SJAS habitat suitability, (4) use the model to determine the quantity and quality of remaining habitat, and (5) use these results to develop conservation recommendations. SJAS were detected on 160 of the 326 sites we surveyed using automated camera stations. Sites with SJAS typically were in arid upland shrub scrub communities where desert saltbush (Atriplex polycarpa) or jointfir (Ephedra californica) were the dominant shrubs, although shrubs need not be present for SJAS to be present. Sites with SJAS usually had relatively sparse ground cover with >10% bare ground and Arabian grass (Schismus arabicus) was the dominant grass. SJAS were more likely to occur on sites where kangaroo rats (Dipodomys spp.) were present and burrow abundance was greater, but SJAS were less likely to be present on sites with California ground squirrels (Otospermophilus beecheyi). Based on our habitat suitability model, an estimated 5,931 km2 of high or moderately high quality habitat and 4,753 km2 of lower quality habitat remain. To conserve SJAS, we recommend (1) conducting additional SJAS surveys on sites not surveyed but with suitable habitat, (2) conserving unprotected lands with suitable habitat, (3) managing vegetation on occupied sites if necessary, (4) restoring disturbed lands to increase suitability for SJAS, and (5) conducting translocations of SJAS to unoccupied sites with suitable habitat.

Characterisation of Hydrological Response to Rainfall at Multi Spatio-Temporal Scales in Savannas of Semi-Arid Australia

Rainfall is the main driver of hydrological processes in dryland environments and characterising the rainfall variability and processes of runoff generation are critical for understanding ecosystem function of catchments. Using remote sensing and in situ data sets, we assess the spatial and temporal variability of the rainfall, rainfall–runoff response, and effects on runoff coefficients of antecedent soil moisture and ground cover at different spatial scales. This analysis was undertaken in the Upper Burdekin catchment, northeast Australia, which is a major contributor of sediment and nutrients to the Great Barrier Reef. The high temporal and spatial variability of rainfall are found to exert significant controls on runoff generation processes. Rainfall amount and intensity are the primary runoff controls, and runoff coefficients for wet antecedent conditions were higher than for dry conditions. The majority of runoff occurred via surface runoff generation mechanisms, with subsurface runoff likely contributing little runoff due to the intense nature of rainfall events. MODIS monthly ground cover data showed better results in distinguishing effects of ground cover on runoff that Landsat-derived seasonal ground cover data. We conclude that in the range of moderate to large catchments (193–36,260 km2) runoff generation processes are sensitive to both antecedent soil moisture and ground cover. A higher runoff–ground cover correlation in drier months with sparse ground cover highlighted the critical role of cover at the onset of the wet season (driest period) and how runoff generation is more sensitive to cover in drier months than in wetter months. The monthly water balance analysis indicates that runoff generation in wetter months (January and February) is partially influenced by saturation overland flow, most likely confined to saturated soils in riparian corridors, swales, and areas of shallow soil. By March and continuing through October, the soil “bucket” progressively empties by evapotranspiration, and Hortonian overland flow becomes the dominant, if not exclusive, flow generation process. The results of this study can be used to better understand the rainfall–runoff relationships in dryland environments and subsequent exposure of coral reef ecosystems in Australia and elsewhere to terrestrial runoff.

Habitat Selection and Behaviour of a Reintroduced Passerine: Linking Experimental Restoration, Behaviour and Habitat Ecology

Habitat restoration can play an important role in recovering functioning ecosystems and improving biodiversity. Restoration may be particularly important in improving habitat prior to species reintroductions. We reintroduced seven brown treecreeper (Climacteris picumnus) social groups into two nature reserves in the Australian Capital Territory in south-eastern Australia. This study provided a unique opportunity to understand the interactions between restoration ecology, behavioural ecology and habitat ecology. We examined how experimental restoration treatments (addition of coarse woody debris, variations in ground vegetation cover and nest box installation) influenced the behaviour and microhabitat use of radio-tracked individuals to evaluate the success of restoration treatments. The addition of coarse woody debris benefited the brown treecreeper through increasing the probability of foraging on a log or on the ground. This demonstrated the value of using behaviour as a bio-indicator for restoration success. Based on previous research, we predicted that variations in levels of ground vegetation cover would influence behaviour and substrate use, particularly that brown treecreepers would choose sites with sparse ground cover because this allows better access to food and better vigilance for predators. However, there was little effect of this treatment, which was likely influenced by the limited overall use of the ground layer. There was also little effect of nest boxes on behaviour or substrate use. These results somewhat confound our understanding of the species based on research from extant populations. Our results also have a significant impact regarding using existing knowledge on a species to inform how it will respond to reintroduction and habitat restoration. This study also places great emphasis on the value of applying an experimental framework to ecological restoration, particularly when reintroductions produce unexpected outcomes.

Rehabilitation of an incised ephemeral stream in central New South Wales, Australia: identification of incision causes, rehabilitation techniques and channel response

The degradation of semiarid agricultural rangelands in Australia can be traced back to the 19th century when Europeans expanded into these areas. That environmental degradation remains today and continues to harm agricultural productivity. The rehabilitation of a strongly incised ephemeral stream, ‘Spring Creek’, in central New South Wales, as an example of what can be achieved readily by landowners, is described. The causes of environmental degradation and the main environmental factors leading to the stream erosion were identified, rehabilitation began and the behaviour of the regime for 5 years within Spring Creek and the adjacent floodplain was monitored. It was found that intrinsically unstable sub-soils and sparse ground cover due to persistent grazing by domestic livestock were the major factors leading to incision. Several physical and chemical properties were found to be the primary causes of the soil’s instability. Rehabilitation focussed on stabilising the soils alongside the stream, promoting sedimentation and re-vegetation of the stream bed, with a longer-term objective of increasing the transfer of water, sediments and nutrients between the stream and its adjacent floodplain. The measures, implemented by local landowners, included the provision of in-stream porous rock weirs and the lowering of the grazing pressure on the stream bed and adjacent floodplain. Monitoring in 2007, 2009 and 2011 indicated that sedimentation was substantially faster above weirs than where there were no weirs. The rehabilitative measures resulted in the retention of fine sediment (<0.2 mm) along the stream bed behind weirs.

Restoring Perennial Warm‐Season Grasses as a Means of Reversing Mesophication of Oak Woodlands in Northern Mississippi

AbstractFire suppression has removed an important ecological force previously responsible for shaping many plant communities throughout the world. Upland areas of north‐central Mississippi that have been protected from fire are now closed‐canopy forests including species known to be uncommon as bearing/witness trees in upland portions of the landscape (historically off‐site species) and sparse ground cover vegetation. Anecdotal evidence suggests that warm‐season grasses were prevalent in the understory of these communities, which could have provided more consistent fuel. We corroborate the historic presence of these grasses by looking at their natural co‐occurrence with oak regeneration (a requisite of self‐replacing stands of oaks found historically). Restoration of these communities has typically focused on burning and off‐site tree thinning. Utilizing a restoration experiment implementing these treatments, we found significantly reduced understory leaf litter in treatment areas. To test which variables associated with restoration treatments were most important for the survival of these grasses, we measured the effect of leaf litter removal and its interaction with environmental conditions on the survival of transplanted shoots. Survival of little bluestem increased with decreasing canopy density and decreasing leaf litter. Leaf‐litter removal did not increase survival, nor did it interact with either pre‐treatment leaf litter depth or canopy density. These results show that little bluestem benefits from conditions expected historically: increased light and possibly fire.

Evaluation of Coarse and Fine Particulate Sources Using a Portable Aerosol Monitor in a Desert Community

The purpose of this study was to use a portable aerosol monitor as a preliminary screening tool to identify local sources of coarse (PM(10-2.5)) and fine (PM(2.5)) particulate matter within the Coachella Valley, a low-elevation desert community. The portable aerosol monitor proved to be useful in identifying particle sources unique to the region, namely, sand dunes with sparse ground cover (vegetation), a river wash, and diesel truck and freight train traffic. The general limitations relate to discrepancies in the fraction of PM(10-2.5) when compared to regional air quality data and a lack of accurate mass-based data.

Fine Root Biomass and Its Relationship to Evapotranspiration in Woody and Grassy Vegetation Covers for Ecological Restoration of Waste Storage and Mining Landscapes

Production and distribution of fine roots (≤2.0 mm diameter) are central to belowground ecological processes. This is especially true where vegetation serves as a pump to prevent saturation of soil and possible drainage of excess water into or from potentially toxic waste material stored underground or in mounds aboveground. In this study undertaken near Sydney in Australia, we determined fine root biomass and evapotranspiration (ET) on a waste disposal site restored with either a 15-year-old grass sward or plantations of mixed woody species that were either 5 years old (plantation-5) with a vigorous groundcover of pasture legumes and grasses, or 3 years old (plantation-3) with sparse groundcover. These sites were compared with nearby remnant woodland; all four were located within 0.5-km radius at the same site. Ranking of fine root biomass was in the order woodland (12.3 Mg ha−1) > plantation-5 (8.3 Mg ha−1) > grass (4.9 Mg ha−1) > plantation-3 (1.2 Mg ha−1) and was not correlated with nutrient contents in soil or plants, but reflected the form and age of the vegetation covers. Trends in root length density (RLD) and root area index (RAI) followed those in root biomass, but the differences in RAI were larger than those in biomass amongst the vegetation covers. Annual ET in the dry year of 2009 was similar in the three woody vegetation covers (652–683 mm) and was at least 15% larger than for the grass (555 mm), which experienced restrained growth in winter and periodic mowing. This resulted in drainage from the grass cover while there was no drainage from any of the woody vegetation covers. In plantation-5, root biomass, RAI and RLD were reduced in the rain shadow side of the tree rows. Similarly, the amount and depth of rooting in the groundcover were reduced close to the trees compared to midway between rows. Differences in the root variables were larger than those in ET, which suggested that more roots were produced than were needed for water uptake and/or presence of considerable amounts of necromass. We conclude that vegetation covers, such as plantation-5 consisting of widely spaced trees and a heavy groundcover containing winter-active pasture legumes, will promote year-round water-use with a reduced risk of deep rooting that could breach buried wastes. This function could be sustained through progressive thinning of trees to account for not more than 25% of the whole canopy cover; this will minimize competition for limited soil-water and thereby constrain deep rooting as vegetation ages and attains climax.

Habitat use by the jacky lizard Amphibolurus muricatus in a highly degraded urban area

Abstract Over time native vegetation remnants in urban areas are typically eroded in size and number due to pressures from urban expansion and consolidation. Such remnants, frequently neglected and invaded by weeds, may constitute the last remaining habitat for some species' populations in urban areas. In the restoration of remnants for biodiversity, weed removal is often a high priority but there is a dearth of information on the role that exotic vegetation plays as habitat for fauna such as small reptiles. We investigated the vegetation type preference of urban remnants at the edge of a Sydney golf course by Amphibolurus muricatus, the native jacky lizard. The three vegetation types present were Eastern Suburbs Banksia Scrub (an Endangered Ecological Community) with sparse groundcover, dense stands of the introduced Eragrostis curvula African love grass, and open fairways of lawn: three structurally different habitats. Captured jacky lizards were spooled and their movements traced by following the thread left as they moved through their home range. Jacky lizards preferred areas that afford them most cover. While they foraged throughout the stands of love grass, they tended to avoid the edge of native vegetation remnants. They also basked on the lawn close to the vegetation where they had recently foraged, or traversed it to enter natural vegetation or grass. We concluded that introduced love grass offered additional habitat because of the relatively dense vegetation cover, and that areas should not be managed with the assumption that invasive weeds are detrimental to native species without appropriate assessment.

Effect of ground cover on splash and sheetwash erosion over a steep forested hillslope: A plot-scale study

The contributions and relationships of erosion by splash and overland flow over a steep slope in a Japanese beech forest in plots with different percentages of ground cover were examined. Three erosion plots (2 m wide × 5 m long) with average understory coverage of 1%, 45%, and 94% were installed. Sediment transported by rain splash and by overland flow was sampled separately. For the plots with sparse, moderate, and high understory coverage, the average proportions of splash soil to total soil erosion during the monitoring period were 16%, 32%, and 18%, respectively. A significant correlation between the amount of splash soil and precipitation was found in the plots with 1% and 45% understory coverage, whereas no statistical relationship was identified for the plot with high understory coverage. At the sparse ground cover plot showing the largest sediment movement, the contribution of splash transport decreased with increasing precipitation. The amount of sheetwash erosion was significantly correlated with the amount of splash soil under the condition of sparse ground cover. This relationship was more pronounced during high precipitation events and the rainy season. Splash contribution to the sediment transport was in the range of 0.8%–76.7%, 2.8%–81% and 2.1%–60.8% for plot with high, moderate and low ground cover, respectively. The sparse ground cover showed the largest variation of splash and sheetwash contribution in soil erosion. This variability was due to variation in ground cover and soil surface wetness condition which led to a variation of detachment and non-linear relationship of sheetwash splash.

Seasonal Dynamics of Small Mammals and Vegetation in A Gulf Cordgrass Community

Abstract We compared small mammals in Gulf cordgrass (Spartina spartinae) to coastal-prairie and low-marsh, Spartina alterniflora communities, and we considered the effect of standing-crop biomass and nutrient concentration in plants in the Gulf cordgrass community on dynamics of populations of small mammals. We predicted lower species richness and density of small mammals and shorter residence time in Gulf cordgrass because of little vertical habitat structure, sparse ground cover, and low abundance of dicots, plants that contain nutrients necessary for reproduction by hispid cotton rats (Sigmodon hispidus). Richness in Gulf cordgrass (seven species of rodents) was similar to coastal prairie (six species plus three non-native rodents) with S. hispidus and fulvous harvest mice (Reithrodontomys fulvescens) numerically dominant in both communities. Density of S. hispidus was higher in Gulf cordgrass likely reflecting high standing-crop biomass; however, lack of ground cover contributed to low residence time...

Influence of historic sheep grazing on vegetation and soil properties of a Desert Steppe in Inner Mongolia

Grazing intensity and grassland degradation in China has increased with a growing livestock population. The Desert Steppe is vulnerable to the impacts of livestock because of relatively short and sparse ground cover and sandy soil. This study investigates the effects of historic sheep grazing on the vegetation and soil properties of a Desert Steppe community. The experiment was conducted at three sites (replicates) in Siziwang Banner in Inner Mongolia with four treatments defined along an historic grazing gradient: ungrazed (control), lightly grazed (LG), moderately grazed (MG) and heavily grazed (HG). The grazing treatments were classified based on species composition and ground cover. The vegetation and soil properties in each treatment and replicate were assessed in fall 2005. The vegetation total N (TN) and P (TP) concentrations and δ 15N levels were not affected ( P > 0.05) by grazing. Grazing increased ( P = 0.02) soil bulk density but had no effect on soil TN and TP concentrations or δ 15N levels ( P > 0.05). However, HG resulted in 16.4, 11.4 and 7.6% reductions in soil organic carbon (OC), TN and TP concentrations, respectively. Grazing had no effect ( P > 0.05) on the concentrations of soil available P, available N (NO 3 − and NH 4 +), electrical conductivity, pH or soluble ions (Na +, K +, Ca 2+, Mg 2+, Cl − and SO 4 2−). The vegetation of the Desert Steppe is generally tolerant of grazing pressure but is relatively unproductive, supporting a smaller number of livestock than the more mesic grasslands. Therefore, treatment differences were generally not detected. However, the combination of sandy soils (∼70%) and generally reduced litter and plant cover with increased grazing pressure suggests that the Desert Steppe is vulnerable to soil erosion. This risk may be reduced by ensuring appropriate grazing pressure and animal distribution with judicious herding.

Habitat choice of Red-breasted Flycatchers Ficedula parva is dependent on forestry management and game activity in a deciduous forest in Vienna (Austria)

Capsule Forest management and game populations have a major impact on the distribution of Red-breasted Flycatchers. Aims To improve the understanding of habitat choice by Red-breasted Flycatchers and to provide a basis for nature conservation measures. Methods The abundance and distribution of Red-breasted Flycatchers were investigated on 23 survey areas of approximately 150 ha. Habitat structure was measured at 42 points in territories and at 151 control points outside territories. Differences in forest structure between territories and control points were highlighted using discriminant function analyses. Results Territories of Red-breasted Flycatchers correlated positively with the portion of hornbeam, the age of the stands and volume of lying dead trunks. Territories were mainly found in stands with high levels of mammalian game activity and accordingly a more sparse bush layer and less ground cover. Territories were closer to ditches than to control points. Red-breasted Flycatchers avoided stands under intensive forestry management. Conclusion Along with forestry management, the activity of mammalian game has major impacts on forest structure. Accordingly, the effect of mammalian game activity can have important implications for nature conservation.

Habitat Selection by Swainson's Warblers Breeding in Loblolly Pine Plantations in Southeastern Louisiana

Abstract Although Swainson's warbler (Limnothlypis swainsonii) is typically associated with bottomland hardwood forests, they also breed in even-age pine (Pinus spp.) plantations. We used mist nets and point counts from 1998–2000 to survey intensively managed even-age loblolly pine (P. taeda) plantations of different age classes and management histories to determine breeding status and stand structure preferences of Swainson's warbler in southeastern Louisiana, USA. We detected Swainson's warblers in 23 of 124 sampled loblolly pine stands. We also confirmed breeding in 7–24-year-old pine stands. We found Swainson's warblers in pine stands that had well-developed canopy closure, abundant understory vegetation, and sparse live ground cover. Floristic differences between hardwood and pine breeding habitats demonstrate that Swainson's warblers do not require specific vegetation composition, although they discriminate within habitats based on physical structure of vegetation. Although management of Swainson's ...

Influence of rocky landscape features and fire regime on vegetation dynamics in AppalachianQuercusforests

AbstractQuestion: How do interactions between rocky landscape features and fire regime influence vegetation dynamics?Location: Continental Eastern USA.Methods: We measured vegetation, disturbance and site characteristics in 40 pairs of rocky and non‐rocky plots: 20 in recently burned stands, and 20 in stands with no evidence of recent fire (‘unburned’ stands). Two‐way analysis of variance (ANOVA) was used to assess the main and interaction effects of fire and rock cover on plant community composition.Results: In burned stands, rock cover had a strong influence on vegetation. Non‐rocky ‘matrix’ forests were dominated byQuercus, and had abundant ground cover and advance regeneration of early and mid‐successional tree species. Burned rocky patches supported greater density of fire‐sensitive species such asAcer rubrum, Sassafras albidumandNyssa sylvaticaand had little advance regeneration or ground cover.Quercushad fewer fire scars and catfaces (open, basal wounds) on rocky patches, suggesting that rocky features mitigate fire severity. In unburned stands, differences between rocky and non‐rocky patches were less distinct, with both patch types having sparse ground cover, little tree regeneration, and high understorey densities of relatively shade tolerantA. rubrum, N. sylvaticaandBetula lenta.Conclusion: Under a sustained fire regime, heterogeneity in rock cover created a mosaic where fire‐adapted species such asQuercusdominate the landscape, but where fire‐sensitive species persisted in isolated pockets of lower fire severity. Without fire, species and landscape richness may decline as early‐mid successional species are replaced by more shade tolerant competitors.

Hedera helix L.

Araliaceae, Schefflereae. Climbing, sometimes reaching 30 m, or prostrate and creeping, forming extensive carpets. Woody stems up to 25 cm diameter, young twigs pubescent with stellate to peltate hairs, and densely furnished with adventitious roots. Leaves petiolate, simple, alternate, exstipulate, coriaceous, glabrous, evergreen; those of climbing or creeping stems 4–10 ( − 25) cm, palmately lobed with 3–5 triangular, entire lobes; leaves of flowering stems 6–10 cm, entire, ovate or rhombic. Leaves shining, dark green above, often with pale veins, paler green below; may become pale green/ yellow in late summer, and upper surface sometimes tinged with purple in winter. Flowers actinomorphic, c. 20 in terminal globose umbels, which may be arranged into panicles. Sepals 5, very small, deltate. Petals 5( − 6), yellowish-green, 3–4 mm, triangular-ovate, somewhat hooded at apex; free. Flowers hermaphrodite, stamens 5; ovary inferior, 5-celled, styles joined into a column. Nectar secreted by a domed disk surrounding the styles. Peduncle, pedicels and receptacle stellate-tomentose; pedicels not jointed. Fruit a berry, bluishor greenishblack (rarely yellow or white), globose, 6–8 mm. Pulp purple, seeds 1–5, c . 35 mg dry mass, rugose, whitish; embryo small, endosperm ruminate. There is considerable disagreement over the taxonomy of the ivies ( Hedera spp.), with the number of European species being cited as between one and six. Three subspecies of Hedera helix L. (hereafter ‘ivy’) are recognized in Fl. Eur.: ssp. helix , ssp. poetarum and ssp. canariensis . ‘ Hedera hibernica ’ (‘Irish ivy’) is recognized only as a horticultural form that is somewhat intermediate between H. helix ssp. helix and ssp. canariensis . Stace (1997) places ssp. canariensis with H. algeriensis Hibberd, and recognizes ‘ H. hibernica ’ as a subspecies of H. helix – ssp. hibernica (G. Kirchn.) D.C. McClint, along with ssp. helix (the common British ivy) and the yellow-fruited garden-escape ssp. poetarum Nyman, from the Mediterranean. Recent molecular data suggest that ssp. helix and ssp. hibernica may represent distinct species, with ssp. helix being the (diploid) maternal parent of the tetraploid ssp. hibernica (Ackerfield & Wen 2003). They are distinguishable by their cpDNA phylogeny, by their trichome morphology and by aspects of their ecology (McAllister 1981; McAllister & Rutherford 1990; Ackerfield & Wen 2002, 2003; Grivet & Petit 2002). Throughout this account Irish ivy will be treated as ssp. hibernica of H. helix , as in much of the older literature the subspecies concerned have not been distinguished. Hundreds of cultivars of H. helix and its subspecies are recognized in the horticultural trade.

Fine‐scale habitat preferences and habitat partitioning by three mycophagous mammals in tropical wet sclerophyll forest, north‐eastern Australia

Abstract Fine‐scale habitat preferences of three co‐occurring mycophagous mammals were examined in a tropical wet sclerophyll forest community in north‐eastern Australia. Two of the three mammal species responded to fine‐scale variation in vegetation and landform around individual trap locations. At a broad scale, the northern bettong (Bettongia tropica), an endangered marsupial endemic to the Australian wet tropics region, showed a preference for ridges over mid‐slopes and gullies, irrespective of forest type. In contrast, the northern brown bandicoot (Isoodon macrourus), a widespread marsupial, displayed a preference for Eucalyptus woodland over adjacent Allocasuarina forest, irrespective of topographic category. The giant white‐tailed rat (Uromys caudimaculatus), a rodent endemic to the wet tropics, showed no particular preference for either forest type or topographic category. A multiple regression model of mammal capture success against three principal habitat gradients constructed from 21 habitat variables using principal component analysis indicated strong species‐specific preferences for fine‐scale vegetation assemblages. Bettongs preferred areas of Eucalyptus woodland with sparse ground cover, low densities of certain grass species, high density of tree stems and few pig diggings. Bandicoots, in contrast, favoured areas in both forest types with dense ground cover, fewer tree stems and greater numbers of pig diggings; that is, characteristics least favoured by bettongs. The striking differences in fine‐scale habitat preferences of these two mammals of similar body size and broad habitat requirements suggest a high degree of fine‐scale habitat partitioning. White‐tailed rats did not show preference for any of the habitat gradients examined.

FOOD AND PREDATION RISK AS FACTORS RELATED TO FORAGING LOCATIONS OF NORTHERN FLICKERS

Foraging site selection by birds may be related to foraging efficiency, food availability and abundance, and predation risk. We identified selectively used foraging habitat within home ranges of 29 adult radio-tagged Northern Flickers (Colaptes auratus) in British Columbia during the nestling period. We compared habitat characteristics of flicker foraging locations to randomly selected locations in their home range using discriminant function analysis. Foraging plots were located in grassland and were characterized by a lack of tall vegetation, a large percentage of bare ground, and a high density of small anthills. Foraging plots had five times more anthills than random plots. Foraging plots also were closer to trees and forest edges than random plots. The random plots had significantly more medium and tall vegetation than foraging plots, and litter (dead grass) was the most abundant type of cover. Mortality of adult flickers attributed to avian predation while foraging was 14% during 1999 and 3% during 2000. The sparse ground cover of foraging plots likely increased access to food, whereas foraging near trees likely decreased avian predation. The marked selectivity of foraging areas by flickers suggests that foraging ability could be negatively affected by land use practices that alter the structure of ground cover.

Population dynamics of, and habitat use by, Austrlian native rodents in wet sclerophyll forest, Tasmania I. Rattus lutreolus velutinus (Rodentia : Muridae)

A local population of velvet-furred rats, Rattus lutreolus velutinus, was studied for 15 months in wet sclerophyll forest in south-eastem Tasmania using mark-recapture techniques. Individuals in the trappable population were readily caught with 90% of captures being recaptures (73 individuals caught 706 times). During winter and the summer breeding season, all individuals had an equal likelihood of recapture, irrespective of sex, age, season or previous capture history. Habitat use was investigated by analysing floristic and structural variation within a 4-ha trapping grid using TWINSPAN. Four heterogeneous habitat groups were defined and population data are compared among these groups. Areas of densest ground cover were preferred by R. 1. velutinus; open areas were avoided. Throughout the study, female rats were captured in the areas with most cover to 50 cm in height; during winter, males were caught in areas of the trapping grid with more sparse ground cover, in lower numbers than females. At the onset of breeding in summer, numerous males were captured in the areas of thickest ground cover occupied by females. These data are discussed in relation to social spacing, habitat utilisation and female choice.