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Habitat Clearance (habitat + clearance)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

Birds on edge: avian assemblages along forest-agricultural boundaries of central Victoria, Australia

ANIMAL CONSERVATION, Issue 2 2001
Monica J. Campi
Habitat clearance generally produces fragmented landscapes. A major consequence is the creation of large amounts of new ,edge habitat', often of a kind not previously existing, such as abrupt forest- agricultural land interfaces. Much work from around the world suggests that proliferation of edge habitat seriously affects birds reliant on large forest blocks to persist, and the intrusion of edge specialists into areas they did not previously occupy. These processes often generate avifaunal gradients in which assemblages change from the interior to the edge. This effect is explored in the largest remnant block of box-ironbark forest of central Victoria, Australia (about 30,000 ha). Eight radially oriented survey lines were established around the periphery of the block. Along each survey line, five transects with long axes oriented parallel to the edge were positioned with midlines at 40 m, 160 m, 280 m and 400 m into the forest, and one transect 80 m into the agricultural land, yielding a total of 40 transects. Six identical transects were located deep within the forest (> 2 km). There was little evidence of a change in the avifauna from interior to edge, although mean richness was depressed in the edge habitats compared with forest interior transects. These results were essentially the same for ,all species' or ,forest dependent' species. Thus, there is little evidence for marked edge effects on the avifauna of these large forest blocks, although work in intermediate sized remnants (100-1000 ha) is needed to identify thresholds at which edge effects begin to be manifested. [source]

Microsatellites for the Tasmanian devil (Sarcophilus laniarius)

MOLECULAR ECOLOGY RESOURCES, Issue 2 2003
Menna E. Jones
Abstract The Tasmanian devil (Sarcophilus laniarius), a medium-sized predator/scavenger, is the largest member of the short-lived carnivorous marsupial Family Dasyuridae. Now restricted to Tasmania, populations are impacted by habitat clearance and anthropogenic mortality and genetic studies could be of value in informing levels of genetic diversity, mating system, dispersal and the effects of natural and anthropogenic landscape features on gene flow. Microsatellite markers were isolated from a partial, size-selected genomic library that was enriched for microsatellite sequences. Primer pairs were developed for 11 polymorphic dinucleotide microsatellite loci that conform with Hardy,Weinberg equilibrium and reveal moderate genetic variability across the species range. [source]

Spatial ecology of a threatened python (Morelia spilota imbricata) and the effects of anthropogenic habitat change

AUSTRAL ECOLOGY, Issue 3 2005
D. PEARSON
Abstract Large predators play important ecological roles, but often are sensitive to habitat changes and thus are early casualties of habitat perturbation. Pythons are among the largest predators in many Australian environments, and hence warrant conservation-orientated research. Carpet pythons (Morelia spilota imbricata) have declined across much of south-western Australia presumably because of habitat clearance and degradation. Information on habitat use, home range sizes and movements is needed to plan for the conservation of this important predator. We studied pythons at two study sites (Garden Island and Dryandra Woodland) with markedly different climates, habitat types and disturbance histories. We surgically implanted radio-transmitters in 91 pythons and tracked them for periods of 1 month to 4 years. Dryandra pythons remained inactive inside tree hollows during cooler months (May,September), whereas some (especially small) pythons on Garden Island continued to move and feed. Overall weekly displacements (mean = 100,150 m) were similar at the two study sites and among sex/age classes, except that reproductive females were sedentary during summer while they were incubating eggs. Home ranges averaged 15,20 ha. Adult male pythons had larger home ranges than adult females at Dryandra, but not at Garden Island. Radio-tracked snakes at Dryandra exhibited high site fidelity, returning to previously occupied logs after long absences and reusing tree hollows for winter shelter. Many of the logs used by snakes had been felled during plantation establishment >70 years ago, with little subsequent regeneration of source trees. In contrast, Garden Island snakes usually sheltered under dense shrubs. Habitat usage was similar among different sex/age classes of snakes at each site, except that juvenile pythons were more arboreal than adults. Although carpet pythons demonstrate great flexibility in habitat use, certain habitat elements appear critical for the persistence of viable populations. Fire plays a central role in this process, albeit in complex ways. For example, low-intensity fires reduce the availability of hollow logs on the ground at Dryandra and fail to regenerate shrub thickets required by prey species. Paradoxically, high-intensity fires stimulate shrub thickets and fell trees creating new logs , but might also threaten overwinter trees. Thus, the impact of disturbances (such as wildfires) on the viability of python populations will be mediated in complex ways by alteration to important microhabitats such as vegetation cover or log availability. At Dryandra, landscape management should include occasional fire events to generate new logs as well as shrub thickets used by prey. Strategic burning may also be required at Garden Island to regenerate some vegetation communities. [source]

Sex in Space: Pollination among Spatially Isolated Plants

BIOTROPICA, Issue 2 2004
Jaboury Ghazoul
ABSTRACT Plant distributions are changing at unprecedented rates, primarily due to habitat clearance and the spread of alien invasive species. Landscape pattern and local density can affect plant sexual processes, particularly those mediated by biotic vectors, by acting on the composition and behavior of pollinators and seed dispersers. Ecologists are now grappling with the likely effects of these altered processes on future forest composition as existing plant reproductive mutualisms break down or adjust to new spatial circumstances. Here, we introduce five papers that address pollinator responses and pollination outcomes in a variety of human-dominated landscapes and emphasize the need to better understand the dynamic nature of plant,pollinator interactions. [source]