scholarly journals How Do Landscape Structure, Management and Habitat Quality Drive the Colonization of Habitat Patches by the Dryad Butterfly (Lepidoptera: Satyrinae) in Fragmented Grassland?

PLoS ONE ◽  
2015 ◽  
Vol 10 (9) ◽  
pp. e0138557 ◽  
Author(s):  
Konrad Kalarus ◽  
Piotr Nowicki
Keyword(s):  
Habitat Quality ◽  
Landscape Structure ◽  
Habitat Patches

scholarly journals Critical threshold effects of benthiscape structure on stream herbivore movement

2007 ◽  
Vol 362 (1479) ◽  
pp. 461-472 ◽  
Author(s):  
Julian D Olden
Keyword(s):  
Functional Connectivity ◽  
Current Velocity ◽  
Landscape Structure ◽  
Species Interactions ◽  
Animal Movement ◽  
Critical Threshold ◽  
Future Research ◽  
Threshold Effects ◽  
Habitat Patches ◽  
Critical Thresholds

Abstract In landscape ecology, substantial theoretical progress has been made in understanding how critical threshold levels of habitat loss may result in sudden changes in landscape connectivity to animal movement. Empirical evidence for such thresholds in real systems, however, remains scarce. Streambed landscapes provide a strong testing ground for studying critical thresholds because organisms are faced with substantial environmental heterogeneity while attempting to overcome the physical force of water. In this study, I report on the results from a series of experiments investigating the influence of habitat abundance and current velocity on the movement dynamics of two stream herbivores (caddisfly larva Agapetus boulderensis and snail Physa sp.) that differ substantially in how they perceive landscape structure. Specifically, I ask whether critical thresholds to herbivore movement exist in streambed landscapes. By exploiting the pattern recognition capabilities of artificial neural networks, I found that the rate, sinuosity and directionality of movement by Agapetus and Physa varied nonlinearly according to the abundance of habitat patches, current velocity and habitat–current interaction. Both the study organisms exhibited threshold responses to habitat abundance, yet the location and slope of these thresholds differed between species and with respect to different current velocities. These results suggest that a critical threshold in functional connectivity (i.e. the connection of habitat patches by dispersal) is not an inherent property of the landscape, but in fact emerges from the interplay of species' interactions with landscape structure. Moreover, current velocity interacted with habitat abundance to elicit strong upstream-oriented movement for both the species. This suggests that dispersing individuals may be polarized in the upstream direction and therefore functional connectivity is not equal in all directions. Such results highlight the need for future research addressing the sources of variability of critical threshold effects in ecological phenomena.

scholarly journals Genetic Variation of Typical Plant Species in Hay Meadows: The Effect of Land Use History, Landscape Structure, and Habitat Quality

2020 ◽  
Vol 8 ◽  
Author(s):  
Ellen Pagel ◽  
Theresa A. Lehmair ◽  
Peter Poschlod ◽  
Christoph Reisch
Keyword(s):  
Genetic Diversity ◽  
Land Use ◽  
Genetic Variation ◽  
Plant Species ◽  
Habitat Quality ◽  
Landscape Structure ◽  
Land Use History ◽  
Global Changes ◽  
Hay Meadows ◽  
Starting Point

Global changes in land use are threatening the diversity of many ecosystems on both the intra- and interspecific levels. Among these ecosystems are the species-rich hay meadows, which have drastically declined in quality and quantity, due to land use intensification or abandonment in recent decades. The remaining genetic resources of their plant species must therefore be protected. To determine the driving forces impacting genetic variation in common hay meadow species (Dactylis glomerata, Heracleum sphondylium, and Trifolium pratense), we used data on the land use history, historic and present landscape structure and habitat quality. Our results showed average genetic diversity within the study sites, with low differentiation levels and a high gene flow among grasslands. Land use history, landscape structure and habitat quality were found to be related to the distribution of genetic diversity in the studied species, highlighting the complex forces acting in these ecosystems and showing the specific impact of litter accumulation on genetic diversity. Both historic and current environmental variables influence genetic diversity, demonstrating the importance of the land use history of a habitat. The most important group of variables impacting genetic variation in all three species was the landscape structure (e.g., distance to the nearest-located urban area or grassland). Also important was the influence of litter cover on genetic diversity in D. glomerata, which provides an interesting starting point for further research.

scholarly journals Does Body Size Affect a Bird's Sensitivity to Patch Size and Landscape Structure?

The Condor ◽  
2006 ◽  
Vol 108 (4) ◽  
pp. 808-816
Author(s):  
Maiken Winter ◽  
Douglas H. Johnson ◽  
Jill A. Shaffer
Keyword(s):  
Body Size ◽  
Tallgrass Prairie ◽  
Landscape Structure ◽  
Patch Size ◽  
Bird Species ◽  
Threshold Effect ◽  
Conservation Strategy ◽  
Woody Vegetation ◽  
Habitat Patches ◽  
Surrounding Landscape

Abstract Abstract Larger birds are generally more strongly affected by habitat loss and fragmentation than are smaller ones because they require more resources and thus larger habitat patches. Consequently, conservation actions often favor the creation or protection of larger over smaller patches. However, in grassland systems the boundaries between a patch and the surrounding landscape, and thus the perceived size of a patch, can be indistinct. We investigated whether eight grassland bird species with different body sizes perceived variation in patch size and landscape structure in a consistent manner. Data were collected from surveys conducted in 44 patches of northern tallgrass prairie during 1998–2001. The response to patch size was very similar among species regardless of body size (density was little affected by patch size), except in the Greater Prairie-Chicken (Tympanuchus cupido), which showed a threshold effect and was not found in patches smaller than 140 ha. In landscapes containing 0%–30% woody vegetation, smaller species responded more negatively to increases in the percentage of woody vegetation than larger species, but above an apparent threshold of 30%, larger species were not detected. Further analyses revealed that the observed variation in responses to patch size and landscape structure among species was not solely due to body size per se, but to other differences among species. These results indicate that a stringent application of concepts requiring larger habitat patches for larger species appears to limit the number of grassland habitats that can be protected and may not always be the most effective conservation strategy.

Sign in / Sign up

Export Citation Format

Share Document