The Relative Importance of Patch Area and Perimeter-Area Ratio to Grassland Breeding Birds

Helzer, Christopher J.

doi:10.2307/2641409

Cited by 52 publications

(89 citation statements)

References 23 publications

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“…area and perimeter) and soil edaphic (e.g. salinity, redox, moisture, texture) characteristics of the transition zones might reflect changes in species' richness and distribution (Cantero et al, 1998;Helzer and Jelinski, 1999). Since transition zones might be important for specific species (Morrison et al, 2001), and are sensitive to climate changes and human activities (Peters, 2002a;Puyravaud et al, 1994;Gehrig-Fasel et al, 2007), they have become a hotspot landscape unit for ecologists.…”

Section: Introductionmentioning

confidence: 99%

The role of sexual vs. asexual recruitment of <i>Artemisia wudanica</i> in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

et al. 2016

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Abstract. Artemisia wudanica is an endemic, perennial, pioneering psammophyte species in the sand dune ecosystems of western Horqin Sand Land in northern China. However, no studies have addressed how sexual and asexual reproduction modes of A. wudanica perform at the transitional zones between active dune inter-dune lowlands and active dunes. In early spring, quadrats were randomly set up in the study area to monitor surviving seedling and/or ramet density and frequency coming from sexual/asexual reproduction of A. wudanica. Iron sticks were inserted near each quadrat to determine wind erosion intensity (WE). Additionally, soil samples were collected nearby each quadrat to test for soil moisture (SM), organic matter (OM) and pH. Surviving seedlings of A. wudanica showed an inverse response in comparison with ramets to SM, OM and WE. Soil moisture showed the most positive effect, and WE the negative effect, on surviving, sexual reproduction seedlings. Contrarily, WE had the most positive effect, and SM the negative effect, on asexual reproduction ramets. This suggests that increases in SM and decreases in WE should benefit recruitment of A. wudanica seedlings. On the contrary, ramets coming from asexual reproduction showed a different response to environmental factors in transition zone habitats. While SM was not a key constraint for the survival of seedlings, they showed a better, positive response to wind erosion environments. Overall, various study environmental parameters could be improved to foster A. wudanica invasion and settlement in the plant community through different reproductive modes, thereby promoting vegetation restoration and rehabilitation.

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Section: Introductionmentioning

confidence: 99%

The role of sexual vs. asexual recruitment of <i>Artemisia wudanica</i> in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

et al. 2016

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“…Even if a linear relationship exists, our area regression was very sensitive to the bird density values of the two largest fields (outlying points). This does not appear to be an artifact of our range of field sizes, as some previous studies of area sensitivity in grassland birds include area ranges similar to ours (e.g., Helzer and Jelinski 1999), and the effect persisted when area was log-transformed. This suggests that chance values at the largest sites may determine whether or not a study finds a significant effect of area.…”

Section: Statistical Considerationsmentioning

confidence: 59%

“…Bobolinks are declining across much of their range due to habitat loss and fragmentation, and area sensitivity could be contributing to this decline (e.g., Vickery et al 1994). Area sensitivity has been reported for Bobolinks in some studies (Vickery et al 1994;Helzer and Jelinski 1999;Johnson and Igl 2001;Renfrew and Ribic 2002), but not in others (Ribic and Sample 2001;Bakker et al 2002;Ribic et al 2009a). This suggests that, while area may play a role in habitat selection, a different measure that is related to area but has a different underlying mechanism, such as openness, might better explain Bobolink habitat selection.…”

Section: Introductionmentioning

confidence: 93%

“…A variety of alternatives have been proposed, such as core area (as defined by distance from habitat edge) (Temple 1986), perimeter to area ratio (e.g., Helzer and Jelinski 1999;Bakker et al 2002), edge sensitivity (e.g., Fletcher et al 2007), and total habitat available in a landscape (e.g., Bakker et al 2002;Davis 2004;Ribic et al 2009a;Shustack et al 2010). One correlated variable proposed as a cause of area sensitivity is openness (here as a binomial assessment of open or not; Renfrew and Ribic 2002).…”

Section: Introductionmentioning

confidence: 99%

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Testing the role of patch openness as a causal mechanism for apparent area sensitivity in a grassland specialist

et al. 2011

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Area sensitivity, species being disproportionately present on larger habitat patches, has been identified in many taxa. We propose that some apparently area-sensitive species are actually responding to how open a habitat patch is, rather than to patch size. We tested this hypothesis for Bobolinks (Dolichonyx oryzivorus) by comparing density and occupancy to a novel openness index, patch area, and edge effects. Bobolink density and occupancy showed significant relationships with openness, but logistic models based on an openness occupancy threshold had greater explanatory power. Thresholds remained approximately consistent from June through August, and shifted to be more open in September. Variance partitioning supported the openness index as unique and relevant. We found no relationships between measures of body condition (body mass, body size, circulating corticosterone levels) and either openness or area. Our findings have implications for studies of area sensitivity, especially with regards to inconsistencies reported within species: specifically, (1) whether or not a study finds a species to be area sensitive may depend on whether small, open sites were sampled, and (2) area regressions were sensitive to observed densities at the largest sites, suggesting that variation in these fields could lead to inconsistent area sensitivity responses. Responses to openness may be a consequence of habitat selection mediated by predator effects. Finally, openness measures may have applications for predicting effects of habitat management or development, such as adding wind turbines, in open habitat.

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“…Another patchlevel index based on the perimeter-area ratio is the Fractal Dimension Index (FRAC). It is well known that the more compact shape a patch has, the more stable habitat it can provide for -as it is less affected by the so-called edge effect (Helzer and Jelinski, 1999). Shape Index has an interval of 1 to +∞, while Fractal Dimension Index has an interval of 1 to 2 (Szabó, 2009).…”

Section: Introductionmentioning

confidence: 99%

Assessment of ecological values of greening landscape elements in the Great Hungarian Plain

Máté

2017

Journal of Environmental Geography

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The research examines the effects of agricultural subsidies on the landscape structure. According to the hypothesis, greening -which has been introduced as part of the European Union's Common Agriculture Policy (EU CAP) reform -, if it is properly controlled and applied, can be a suitable tool for habitat network development. Landscape elements eligible for greening can function as significant landscape structural elements, and can promote the achievement of goals e.g. in the preservation of biodiversity. As part of this research, field surveys were performed in 2016 and 2017 in the Great Hungarian Plain, where significant landscape elements were assessed and documented in the sample area. During the research, Shape Index and Fractal Dimension Index values for polygonal elements were calculated based on their current extensions in 2016 and in 2017. In line with my basic hypothesis, eligible landscape elements (such as hedgerows, stonewalls, shadoofs and infield trees) do not possess extraordinary ecological values, nor can their persistence be guaranteed solely with greening subsidies. Therefore, they may also not be able to fill their role in the protection of landscape structure and biodiversity in the long term.

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The Relative Importance of Patch Area and Perimeter-Area Ratio to Grassland Breeding Birds

Cited by 52 publications

References 23 publications

The role of sexual vs. asexual recruitment of <i>Artemisia wudanica</i> in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

The role of sexual vs. asexual recruitment of <i>Artemisia wudanica</i> in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

Testing the role of patch openness as a causal mechanism for apparent area sensitivity in a grassland specialist

Assessment of ecological values of greening landscape elements in the Great Hungarian Plain

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The Relative Importance of Patch Area and Perimeter-Area Ratio to Grassland Breeding Birds

Cited by 52 publications

References 23 publications

The role of sexual vs. asexual recruitment of &lt;i&gt;Artemisia wudanica&lt;/i&gt; in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

The role of sexual vs. asexual recruitment of &lt;i&gt;Artemisia wudanica&lt;/i&gt; in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

Testing the role of patch openness as a causal mechanism for apparent area sensitivity in a grassland specialist

Assessment of ecological values of greening landscape elements in the Great Hungarian Plain

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The role of sexual vs. asexual recruitment of <i>Artemisia wudanica</i> in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China

The role of sexual vs. asexual recruitment of <i>Artemisia wudanica</i> in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China