The effect of patch area on birds in central Australian mulga (Acacia aneura) woodland of different times-since-fire.

2013 ◽  
Vol 19 (1) ◽  
pp. 28 ◽  
Author(s):  
Adam J Leavesley ◽  
Geofferey J Cary
Keyword(s):  
National Park ◽  
Patch Size ◽  
Species Turnover ◽  
Bird Communities ◽  
Positive Density ◽  
Patch Area ◽  
Bird Density ◽  
Key Species ◽  
Fixed Area ◽  
Acacia Aneura

It is often assumed that a fine-scaled mosaic of different times-since-fire supports greater biodiversity than a coarsescaled mosaic — the fire mosaic hypothesis. A potential mechanism of the fire mosaic hypothesis is the effect of area on species diversity. We investigated the effect of patch area on bird communities in mulga (Acacia aneura) woodland in central Australia. The study was conducted at Uluru Kata-Tjuta National Park using 55 fixed-area sites classified to the time since last fire: burnt 2002; burnt 1976 and long unburnt. Birds were surveyed in the winter and spring of 2005 and 2006. Of 20 key species, two showed a positive density-area effect (i.e. higher density in larger patches). Patch area did not affect total bird density or species richness. However, species turnover (ß-diversity) was greater in large patches in the burnt 2002 treatment than it was in small patches. There was no effect of patch area on the composition of the bird communities in any of the time-since-fire classes. We concluded that patch area did affect the distribution of some birds in mulga woodland. However, patch area was not a mechanism of the fire mosaic hypothesis because the effects of patch size tended to increase avian diversity in larger patches rather than small.

The effect of fire on birds of mulga woodland in arid central Australia

2010 ◽  
Vol 19 (7) ◽  
pp. 949 ◽  
Author(s):  
Adam J. Leavesley ◽  
Geoffrey J. Cary ◽  
Glenn P. Edwards ◽  
A. Malcolm Gill
Keyword(s):  
Vegetation Structure ◽  
National Park ◽  
Arid Zone ◽  
Canopy Cover ◽  
Bird Community ◽  
Bird Communities ◽  
Time Since Fire ◽  
Central Australia ◽  
Acacia Aneura

The principal ecosystem driver in arid Australia is unpredictable rainfall, but it is hypothesised that fire also plays an important role in determining the distribution of animals. We investigated the effect of fire on birds in mulga (Acacia aneura) woodland in the central Australian arid zone. The study was conducted at Uluru–Kata Tjuta National Park using 63 sites classified into one of three time-since-fire classes: burnt 2002; burnt 1976; and long-unburnt. Birds were sampled in the winter and spring of 2005 and 2006 and vegetation structure was measured at all sites. Vegetation structure varied with time-since-fire. The burnt 2002 treatment was an early seral stage of mulga woodland and effectively a grassland. The burnt 1976 and long-unburnt treatments were both woodland, but the long-unburnt treatment had greater canopy cover and height. The bird community in the burnt 2002 treatment was characterised by granivores, whereas that in the burnt 1976 and long-unburnt treatments was characterised by foliar insectivores. All species showed monotonic responses to time-since-fire (i.e. none were at significantly highest density in the burnt 1976 treatment). Fire in mulga woodland changed the vegetation structure and consequently also changed the composition of the bird communities.

Heat/mass transport in shear flow over a heterogeneous surface with first-order surface-reactive domains

2015 ◽  
Vol 782 ◽  
pp. 260-299 ◽  
Author(s):  
Preyas N. Shah ◽  
Eric S. G. Shaqfeh
Keyword(s):  
Mass Transfer ◽  
Shear Rate ◽  
Shear Flow ◽  
Reaction Rate ◽  
Patch Size ◽  
Patch Area ◽  
First Order ◽  
Effective Boundary ◽  
Order Surface ◽  
Slip Distance

Surfaces that include heterogeneous mass transfer at the microscale are ubiquitous in nature and engineering. Many such media are modelled via an effective surface reaction rate or mass transfer coefficient employing the conventional ansatz of kinetically limited transport at the microscale. However, this assumption is not always valid, particularly when there is strong flow. We are interested in modelling reactive and/or porous surfaces that occur in systems where the effective Damköhler number at the microscale can be $O(1)$ and the local Péclet number may be large. In order to expand the range of the effective mass transfer surface coefficient, we study transport from a uniform bath of species in an unbounded shear flow over a flat surface. This surface has a heterogeneous distribution of first-order surface-reactive circular patches (or pores). To understand the physics at the length scale of the patch size, we first analyse the flux to a single reactive patch. We use both analytic and boundary element simulations for this purpose. The shear flow induces a 3-D concentration wake structure downstream of the patch. When two patches are aligned in the shear direction, the wakes interact to reduce the per patch flux compared with the single-patch case. Having determined the length scale of the interaction between two patches, we study the transport to a periodic and disordered distribution of patches again using analytic and boundary integral techniques. We obtain, up to non-dilute patch area fraction, an effective boundary condition for the transport to the patches that depends on the local mass transfer coefficient (or reaction rate) and shear rate. We demonstrate that this boundary condition replaces the details of the heterogeneous surfaces at a wall-normal effective slip distance also determined for non-dilute patch area fractions. The slip distance again depends on the shear rate, and weakly on the reaction rate, and scales with the patch size. These effective boundary conditions can be used directly in large-scale physics simulations as long as the local shear rate, reaction rate and patch area fraction are known.

INVERSE PATCHWORK TRANSFORM

Fractals ◽  
1994 ◽  
Vol 02 (03) ◽  
pp. 429-431
Author(s):  
P. D. CHARLES ◽  
C. A. BROWN ◽  
W. A. JOHNSEN
Keyword(s):  
Surface Topography ◽  
Surface Area ◽  
Patch Size ◽  
Basis Functions ◽  
Patch Area ◽  
Mathematical Basis ◽  
Surface Design ◽  
Surface Data ◽  
Design And Manufacture

The patchwork method uses triangular patches to estimate surface area as a function of patch size. The patch area can be interpreted as a scale of observation. Using the patchwork method, one can identify crossover scales, or thresholds, which distinguish scales where a surface is best described by Euclidean or fractal geometries. An inverse patchwork transform is proposed by which a set of relative areas and crossover data can be transformed to derive topographical data. The inverse patchwork transform and patchwork method provide mathematical basis functions for conversion between two domains-scales of observation and surface topography, providing a system for synthesizing surface data with desired characteristics. This method can also serve as a tool for aiding in surface design and manufacture.

scholarly journals Effects of transhumance route on the richness and composition of bird communities in Tsimanampesotse National Park

2015 ◽  
Vol 10 (3) ◽  
pp. 110 ◽  
Author(s):  
Lalatiana O. Randriamiharisoa ◽  
Daniel Rakotondravony ◽  
Marie Jeanne Raherilalao ◽  
Amadou Ranirison ◽  
Lucienne Wilmé ◽  
...  
Keyword(s):  
National Park ◽  
Bird Communities

scholarly journals Composition and Functional Diversity in Bird Communities in a Protected Humid Coastal Savanna

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Alfan A. Rija ◽  
Abubakari S. Mgelwa ◽  
Robert B. Modest ◽  
Shombe N. Hassan
Keyword(s):  
Species Richness ◽  
National Park ◽  
Bird Species ◽  
Bird Communities ◽  
Large Mammals ◽  
Feeding Guild ◽  
Bird Species Richness ◽  
Heterogeneous Landscape ◽  
Species Lists ◽  
Associated Species

Our current understanding of the vertebrate communities of a newly gazetted Tanzanian coastal national park is limited and strongly taxonomically biased towards large mammals. We conducted bird assessments in three sites in Saadani National Park using species lists to analyze some parameters to inform biodiversity conservation in the area. We recorded 3112 individuals in 268 species falling in 66 families, including 2 endangered, 2 vulnerable, and 6 near threatened species. Both species richness and species diversity varied between sites. Species relative abundances were not different between the sites although some functional groups, especially granivores, were more abundant than others. Bird assemblages included 21 forest specialists (FF-species), 35 forest generalists (F-species), and 68 forest visitors (f-species) overlapping among bushland, wooded grassland, grassland, and thickets suggesting presence of important microhabitats for the forest-associated species in this ecosystem. Bird species richness in a feeding guild also showed marked overlap between habitats suggesting availability of rich food resources for the birds. This paper highlights the importance of maintaining a structurally heterogeneous landscape to sustain diverse bird communities in the area.

Status, diversity and trends of the bird communities in Volcanoes National Park and surrounds, Rwanda

2019 ◽  
Vol 30 (1) ◽  
pp. 1-20 ◽  
Author(s):  
MIA A. DERHÉ ◽  
DEO TUYISINGIZE ◽  
WINNIE ECKARDT ◽  
FAIDA EMMANUEL ◽  
TARA STOINSKI
Keyword(s):  
National Parks ◽  
National Park ◽  
Mixed Forest ◽  
Basal Area ◽  
Bird Community ◽  
Bird Communities ◽  
Population Pressure ◽  
Bird Diversity ◽  
Albertine Rift ◽  
1960S And 1970S

SummaryThe Volcanoes National Park (VNP) in Rwanda, part of the Virunga massif in the Albertine Rift region, boasts some of Rwanda’s best remaining natural vegetation and is home to many endangered and endemic species. The park has suffered from high levels of degradation and destruction, reducing in size by 50% during the 1960s and 1970s, and remains under threat from illegal activities, human population pressure and climate change. This study is the first to investigate the status and trends of bird communities in the VNP, using a multi-year dataset. We use a five-year dataset, totalling over 3,200 point-counts, both within and around the VNP, to assess the conservation value of the VNP for birds in comparison with other national parks and non-protected areas. We assess bird communities and population trends within and around the parks and identify important habitat factors for birds within the VNP. We found that the VNP hosts a unique bird community compared to other localities, with several Albertine Rift endemics and threatened species occurring in the VNP. Hagenia/ Hypericum woodland, herbaceous vegetation, brush ridge and mixed forest host the highest levels of bird diversity in the VNP, whilst the park’s waterbodies provide key habitat for the endangered Albertine Rift endemic Grauer’s Swamp-warbler (Bradypterus graueri). Elevation had a negative effect on bird diversity in the VNP, whilst the basal area of dead trees, Hagenia and vines had a positive effect. Both inside and outside the VNP, there was a significant decline in abundance and species richness over the sampling years; however, we advocate for further monitoring to confirm these trends. Based on our findings, we recommend effective, targeted management of key habitats for birds within the park, including those identified in this study, in order to mitigate bird declines and conserve the unique bird communities in the VNP.

scholarly journals Scale dependence of biotic homogenisation by urbanisation: a comparison of urban bird communities between central Argentina and northern Finland

2017 ◽  
Vol 3 (2) ◽  
pp. 1-18 ◽  
Author(s):  
Lucas M. Leveau ◽  
Jukka Jokimäki ◽  
Marja-Liisa Kaisanlahti-Jokimäki
Keyword(s):  
Species Turnover ◽  
Regional Scale ◽  
Bird Species ◽  
Bird Community ◽  
Bird Communities ◽  
Urban Habitats ◽  
Suburban Areas ◽  
Biotic Homogenisation ◽  
Community Dissimilarity ◽  
The Town

AbstractRecent studies showed contrasting results about the homogenising force of urbanisation on bird community composition at large and regional scales. We studied whether urbanisation promotes the homogenisation of wintering bird communities and if this varies when comparing towns located within a specific region and towns located in two different biomes of two countries. We used both similarity indices based on the presence/absence data and the abundance data in comparing communities. Processes governing bird community dissimilarity between urbanisation levels were examined with the partitioning of Sörensen index in species turnover and nestedness. We made bird surveys in town centres and suburban habitats of three cities located in the Pampean region of Argentina and in the boreal region of Finland using a single-visit study plot method. Rarefacted species richness did not differ amongst the town centres between the countries, but it was higher in the suburban areas of Argentina than in Finland. At the country-level comparison, we found a higher similarity amongst the town centres than amongst the suburban areas; whereas at the regional comparison, similarity between town centres was comparable to the similarity between suburban areas. The use of an abundance-based index produced a higher similarity between town centre communities of both countries than when using a presence-based index. The dissimilarity between habitats in Argentina was related to nestedness and to species turnover in Finland. Our results indicate that urban-based biotic homogenisation of bird communities is dependent on the scale used, being more evident when comparing cities of different biomes where the same and abundant bird species, such as sparrows and doves, dominate. At the regional scale, quite a high beta-diversity can still be found within urban habitats. Processes of community dissimilarity between urban habitats may differ according to the regional pool of species, being more related to nestedness toward the tropics.

scholarly journals Sea to sky: impacts of residual salmon-derived nutrients on estuarine breeding bird communities

2011 ◽  
Vol 278 (1721) ◽  
pp. 3081-3088 ◽  
Author(s):  
Rachel D. Field ◽  
John D. Reynolds
Keyword(s):  
Pacific Salmon ◽  
Bird Communities ◽  
Oncorhynchus Gorbuscha ◽  
Oncorhynchus Keta ◽  
Breeding Bird ◽  
The North ◽  
Bird Density ◽  
Post Spawning ◽  
The North Pacific ◽  
Forest Habitats

Pacific salmon ( Oncorhynchus spp.) returning to streams around the North Pacific Rim provide a nutrient subsidy to these ecosystems. While many species of animals feed directly on salmon carcasses each autumn, salmon-derived nutrients can also be stored in coastal habitats throughout the year. The effects of this storage legacy on vertebrates in other seasons are not well understood, especially in estuaries, which can receive a large portion of post-spawning salmon nutrients. We examine the effects of residual salmon-derived nutrients, forest habitats and landscape features on summer breeding birds in estuary forests. We compared models containing environmental variables and combined chum ( Oncorhynchus keta ) and pink ( Oncorhynchus gorbuscha ) salmon biomass to test predictions concerning bird density and diversity. We discovered that total bird, insectivore, golden-crowned kinglet and Pacific wren densities and Shannon's diversity in the summer were strongly predicted by salmon biomass in the autumn. For most metrics, this relationship approaches an asymptote beyond 40 000 kg of salmon biomass. Foliage height diversity, watershed catchment area and estuary area were also important predictors of avian communities. Our study suggests that the legacy of salmon nutrients influences breeding bird density and diversity in estuaries that vary across a wide gradient of spawning salmon biomass.

Dry grasslands in Wood Buffalo National Park: reply

1999 ◽  
Vol 77 (7) ◽  
pp. 918-921
Author(s):  
A G Schwarz ◽  
Ross W Wein
Keyword(s):  
National Park ◽  
Vascular Plant ◽  
Summer Rainfall ◽  
Dry Grassland ◽  
Dry Grasslands ◽  
Key Species ◽  
Stipa Comata ◽  
Wood Buffalo National Park ◽  
Trees And Shrubs ◽  
Special Protection

In examining dry grassland areas of Wood Buffalo National Park (WBNP), we used vascular plant indicators commonly found in the grassland landscapes in the southern and central parts of the Prairie Provinces. With distance northward the landscapes become increasingly tree-dominated and the dry grasslands have fewer dry grassland indicator species (about 40 in the area of WBNP) and become smaller in size (about 1 ha in WBNP). Key species are Stipa comata Trin & Rupr., Stipa curtiseta (A.S. Hitchc.) Barkworth, and Stipa columbiana Macoun on the drier sites. Paleontological records and historical documents suggest that these remnant dry grasslands must expand during decades of drought and must contract during decades of higher summer rainfall. We hypothesize that fires might enhance dry grassland expansion by stressing and killing trees and shrubs. Southern dry grassland vascular plant species represent over 7% of the total in WBNP. It is reasonable to hypothesize that these represent special ecotypes that deserve special protection through prescribed burning.Key words: remnant grasslands, Stipa spp., climate change.

scholarly journals Role of delinquent young "orphan" male elephants in high mortality of white rhinoceros in Pilanesberg National Park, South Africa

Koedoe ◽  
2001 ◽  
Vol 44 (1) ◽  
Author(s):  
R. Slotow ◽  
G. Van Dyk
Keyword(s):  
South Africa ◽  
National Park ◽  
Young Male ◽  
Individual Identification ◽  
Historical Sources ◽  
Record Keeping ◽  
Significant Bias ◽  
Key Species ◽  
White Rhinoceros ◽  
First Occurrence

We describe white rhinoceros (Ceratotherium simum) mortality at Pilanesberg National Park, South Africa, focussing on mortality caused by African elephant (Loxodonta africana). We reconstructed records from a range of historical sources, and estimated that up to 49 rhino were killed by elephant. There was confirmed mortality in 1994 and 1996, and based on patterns, we suggest a set of rhino mortality from elephant in 1992. Both sexes and all age classes were victims. There was no significant bias to older animals, but given the rhino population structure, there was a significant bias towards males in adult deaths. The culprits were identified as young male elephants that entered musth about 10 years younger than expected, and maintained musth for a full term at first occurrence. We attributed this to the lack of a mature bull hierarchy in the park, because these elephants were the product of translocation of young animals (<10 years old) remaining from culls in Kruger National Park. We emphasise the need for accurate monitoring and record keeping, and a focus on individual identification of key species in small reserves.

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