Landscape features associated with infection by a malaria parasite (Plasmodium mexicanum) and the importance of multiple scale studies

Parasitology ◽  
2001 ◽  
Vol 122 (5) ◽  
pp. 507-513 ◽  
Author(s):  
R. J. EISEN ◽  
N. M. WRIGHT
Keyword(s):  
Leaf Litter ◽  
Spatial Scales ◽  
Canopy Cover ◽  
Ground Cover ◽  
Sun Exposure ◽  
Water Source ◽  
Multiple Scale ◽  
Infection Prevalence ◽  
Landscape Features ◽  
Cover Type

In a 3-year study, we examined landscape features (aspect, slope, sun exposure, canopy cover, type of ground cover, and nearest water source) that were potentially related to prevalence of infection withPlasmodium mexicanumin fence lizards (Sceloporus occidentalis) within a 4.5 ha study area in northern California, USA. Logistic regression analysis showed that ground cover type was the primary mediator of the probability ofP. mexicanuminfection. Infected lizards were captured more often in rock and/or leaf litter locations than in grassy ones. In another experiment, the study area was divided into 9 sites (0.07–0.33 ha), and infection prevalence was calculated for each. Three sites with high (>30%) infection prevalence had significantly more rocky outcrops and leaf litter than those with low (<20%) or moderate (20–30%) infection prevalence (N= 3 sites each). We conclude that lizard site selection may influence the probability of exposure to infected vectors and thus the likelihood ofP. mexicanuminfection. We also demonstrate that studies at different spatial scales may be required to understand fully the relationship between landscape features and parasite distribution.

Microhabitat separation and niche overlap among five assemblages of tropical skinks

2007 ◽  
Vol 55 (1) ◽  
pp. 15 ◽  
Author(s):  
Brett A. Goodman
Keyword(s):  
Body Size ◽  
Leaf Litter ◽  
Null Model ◽  
Canopy Cover ◽  
Ground Cover ◽  
Niche Overlap ◽  
Microhabitat Use ◽  
Niche Space ◽  
North East ◽  
Species Packing

The niche axes of microhabitat use, activity and size for 21 skink species from five assemblages (Alligator Creek, Cairns, Chillagoe, Cooktown and Mt Bartle Frere) in the biodiverse tropics of north-east Queensland were examined. Species within the same assemblage separated predominantly along two structural microhabitat gradients; one that ranged from microhabitats dominated by large rocks to leaf litter and total ground cover, and a second defined by increasing leaf litter, ground cover, undergrowth, proximity to vegetation and increased canopy cover. All species used available microhabitats non-randomly, with species from the same ecotype (arboreal, generalist, litter-dwelling, rock-using) clustering in multivariate ecological space. Despite evidence of within-assemblage niche overlap, null-model comparisons revealed that only one assemblage (Chillagoe) had greater niche overlap than would be expected by chance. Assemblages with more species occupied smaller niche space, indicating species packing. However, species with more diverse niches were less evenly packed. While most species overlapped in activity time and body size, differences among species from the same ecotype were observed. Despite subtle differences in temporal activity and body size, differences in structural microhabitat use appears to be the dominant niche axis allowing the coexistence of species within these assemblages of tropical skinks.

scholarly journals Habitat preference of Himalayan musk deer (Moschus leucogaster Hodgson, 1839) at Lapchi of Bigu Rural Municipality, Gaurishankar Conservation Area

2021 ◽  
Vol 9 (1) ◽  
pp. 21-28
Author(s):  
Narayan Prasad Koju ◽  
Bijay Bashyal ◽  
Satya Narayan Shah
Keyword(s):  
Habitat Preference ◽  
Canopy Cover ◽  
Ground Cover ◽  
Water Source ◽  
Iucn Red List ◽  
Musk Deer ◽  
Human Settlement ◽  
Conservation Area ◽  
North West ◽  
Rock Exposure

The Himalayan musk deer (Moschus leucogaster) is an endangered species listed in the IUCN Red List and Appendix I of CITES. It is widely but discontinuously distributed in Nepal. A Pellet sign survey was carried in April 2019 in Lapchi valley of Gaurishankar Conservation Area (GCA) in Nepal to assess the habitat preference of Himalayan musk deer. A total of 11 transects of 16348 m length and 10 m wide was surveyed. Seven Parameters: Elevation, Aspect, ground cover, distance from the water source, crown cover, rock exposure, and distance from settlement/cow sheds were recorded from the location where pellet (toilet) of musk deer were recorded to extrapolate the probable habitat map. We recorded a total of 157 musk deer pellet groups in the study area14.27 ± 2.91. The study concluded that the 38.4% (26.5 km2) area of Lapchi valley is the probable habitat of musk deer. The c2 – test suggested that the distribution of musk deer is significantly associated with elevation and aspect of the location. Musk deer mostly preferred habitat between 3600-4000 m elevations, with North-West aspect, ground cover less than 25%, and canopy cover between 25%-50%. Musk deer signs were recorded in areas with rock exposure ranging from as low as less than 25%. Distance from the water source and human settlement affect the distribution of musk deer. The indirect signs were higher near water sources and far from human settlement.

Forest and trees: Shade management, forest proximity and pollinator communities in southern Costa Rica coffee agriculture

2016 ◽  
Vol 32 (5) ◽  
pp. 417-427 ◽  
Author(s):  
S. Amanda Caudill ◽  
Julia N. Brokaw ◽  
Dejeanne Doublet ◽  
Robert A. Rice
Keyword(s):  
Costa Rica ◽  
Spatial Scales ◽  
Canopy Cover ◽  
Ground Cover ◽  
Forest Edge ◽  
Native Forest ◽  
Pollinator Diversity ◽  
Flower Visitation ◽  
Visitation Frequency ◽  
Bee Abundance

AbstractSustained pollinator services within coffee farms depend substantially on a diverse bee community. While studies have been conducted to understand the impacts of forest proximity and farm level management on pollinators, few have examined the interaction between these two spatial scales. We surveyed pollinator communities within 18 sites on a large organic farm surrounded by native forest in southern Costa Rica. We selected sites 0, 50 and 150 m from the forest edge within shaded and sparsely-shaded (sun) portions of the farm to quantify the influence of both shade management and distance to contiguous forest on pollinator communities. Contrary to similar studies, native bees dominated the composition of pollinators on this farm. Overall, pollinator diversity and activity did not differ significantly neither between the shade management types nor among the sites 0, 50 or 150 m from the forest edge. However, pollinator diversity was found to be significantly higher at sun sites near forest (0 m) compared with further away, whereas the diversity was the same for the shade sites regardless of forest proximity. We found that greater numbers of coffee flowers within each site increased bee abundance and flower visitation frequency. Bee abundance was greater in sites with less ground cover and bee diversity and visitation frequencies were higher in sites with greater amounts of shade canopy cover and trees in flower. Based on our results, we suggest including flowering shade trees that provide high levels of canopy cover, maintaining or re-establishing forested areas within or surrounding farms, and eliminating or reducing agrochemical use to increase native pollinator activity and diversity within coffee farms.

scholarly journals Applications of High-Resolution Imaging for Open Field Container Nursery Counting

2018 ◽  
Vol 10 (12) ◽  
pp. 2018 ◽  
Author(s):  
Ying She ◽  
Reza Ehsani ◽  
James Robbins ◽  
Josué Nahún Leiva ◽  
Jim Owen
Keyword(s):  
Vegetation Index ◽  
Ground Cover ◽  
Aerial Images ◽  
Support Vector ◽  
Inventory Data ◽  
Cover Type ◽  
Canopy Area ◽  
Resolution Imaging ◽  
Container Nurseries ◽  
The Stability

Frequent inventory data of container nurseries is needed by growers to ensure proper management and marketing strategies. In this paper, inventory data are estimated from aerial images. Since there are thousands of nursery species, it is difficult to find a generic classification algorithm for all cases. In this paper, the development of classification methods was confined to three representative categories: green foliage, yellow foliage, and flowering plants. Vegetation index thresholding and the support vector machine (SVM) were used for classification. Classification accuracies greater than 97% were obtained for each case. Based on the classification results, an algorithm based on canopy area mapping was built for counting. The effects of flight altitude, container spacing, and ground cover type were evaluated. Results showed that container spacing and interaction of container spacing with ground cover type have a significant effect on counting accuracy. To mimic the practical shipping and moving process, incomplete blocks with different voids were created. Results showed that the more plants removed from the block, the higher the accuracy. The developed algorithm was tested on irregular- or regular-shaped plants and plants with and without flowers to test the stability of the algorithm, and accuracies greater than 94% were obtained.

Effects of logging and fire on small mammals in Mumbulla State Forest, near Bega, New South Wales

1987 ◽  
Vol 14 (2) ◽  
pp. 163 ◽  
Author(s):  
D. Lunney ◽  
B. Cullis ◽  
P. Eby
Keyword(s):  
Small Mammals ◽  
New South ◽  
New South Wales ◽  
Canopy Cover ◽  
Ground Cover ◽  
First Year ◽  
Severe Effect ◽  
South Wales ◽  
Antechinus Stuartii ◽  
Rattus Fuscipes

This study of the effects of logging on small mammals in Mumbulla State Forest on the south coast of New South Wales included the effects of a fire in November 1980 and a drought throughout the study period from June 1980 to June 1983. Rattus fuscipes was sensitive to change: logging had a significant impact on its numbers, response to ground cover, and recapture rate; fire had a more severe effect, and drought retarded the post-fire recovery of the population. The three species of dasyurid marsupials differed markedly in their response to ground cover, canopy cover, logging and fire. Antechinus stuartii was distributed evenly through all habitats and was not affected by logging, but fire had an immediate and adverse effect which was sustained by the intense drought. A. swainsonii markedly preferred the regenerating forest, and was not seen again after the fire, the failure of the population being attributed to its dependence on dense ground cover. Sminthopsis leucopus was found in low numbers, appeared to prefer forest with sparse ground cover, and showed no immediate response to logging or fire; its disappearance by the third year post-fire suggests that regenerating forest is inimical to the survival of this species. Mus musculus showed no response to logging. In the first year following the fire its numbers were still very low, but in the next year there was a short-lived plague which coincided with the only respite in the 3-year drought and, importantly, occurred in the intensely burnt parts of the forest. The options for managing this forest for the conservation of small mammals include minimising fire, retaining unlogged forest, extending the time over which alternate coupes are logged and minimising disturbance from heavy machinery.

scholarly journals The conservation value of South East Asia's highly degraded forests: evidence from leaf-litter ants

2011 ◽  
Vol 366 (1582) ◽  
pp. 3256-3264 ◽  
Author(s):  
Paul Woodcock ◽  
David P. Edwards ◽  
Tom M. Fayle ◽  
Rob J. Newton ◽  
Chey Vun Khen ◽  
...  
Keyword(s):  
Species Richness ◽  
Leaf Litter ◽  
Oil Palm ◽  
Species Turnover ◽  
Spatial Scales ◽  
Forest Conversion ◽  
Conservation Value ◽  
Natural Forests ◽  
Ant Communities ◽  
Logged Forest

South East Asia is widely regarded as a centre of threatened biodiversity owing to extensive logging and forest conversion to agriculture. In particular, forests degraded by repeated rounds of intensive logging are viewed as having little conservation value and are afforded meagre protection from conversion to oil palm. Here, we determine the biological value of such heavily degraded forests by comparing leaf-litter ant communities in unlogged (natural) and twice-logged forests in Sabah, Borneo. We accounted for impacts of logging on habitat heterogeneity by comparing species richness and composition at four nested spatial scales, and examining how species richness was partitioned across the landscape in each habitat. We found that twice-logged forest had fewer species occurrences, lower species richness at small spatial scales and altered species composition compared with natural forests. However, over 80 per cent of species found in unlogged forest were detected within twice-logged forest. Moreover, greater species turnover among sites in twice-logged forest resulted in identical species richness between habitats at the largest spatial scale. While two intensive logging cycles have negative impacts on ant communities, these degraded forests clearly provide important habitat for numerous species and preventing their conversion to oil palm and other crops should be a conservation priority.

scholarly journals Scales of Food Availability for an Endangered Insectivore, The Hawaii Akepa

The Auk ◽  
2002 ◽  
Vol 119 (1) ◽  
pp. 166-174 ◽  
Author(s):  
J. Scott Fretz
Keyword(s):  
Food Availability ◽  
Prey Availability ◽  
Spatial Scales ◽  
Canopy Cover ◽  
Distribution Patterns ◽  
Prey Population ◽  
Suitable Habitat ◽  
Population Declines ◽  
Loxops Coccineus ◽  
A Site

Abstract The Hawaii Akepa (Loxops coccineus coccineus) is an endangered bird that has declined dramatically in the last 100 years, and is now rare or absent from many areas that appear to support suitable habitat. Food availability may play a role in these distribution patterns, but differences in food between sites may arise from different sources. I compared prey availability between a site supporting a large, stable Hawaii Akepa population, and a site from which Hawaii Akepa have declined in the last 100 years for unknown reasons. I used three spatial scales to compare food between sites to explore the basis of differences in food between sites. At a scale appropriate for comparing prey population dynamics (scale 1), I found that prey population densities are similar between sites, suggesting that introduced (or native) predators or parasitoids have not affected prey populations differently between sites. At two larger scales incorporating habitat structure, I found that food availability is much lower at the site of Hawaii Akepa declines. Differences in canopy density per square meter (scale 2), and in canopy cover per square kilometer (scale 3), result in lower food availability that may have effects on individual foraging birds as well as on potential Hawaii Akepa population density. These findings illustrate the importance of explicitly incorporating spatial scale into inquiries about food for Hawaii Akepa, and suggest that the site of population declines may not be suitable habitat with respect to food for this species.

scholarly journals The Influence of Prey Availability and Vegetation Characteristics on Scent Station Visitation Rates of Coyotes, Canis latrans, in a Heterogeneous Environment

2004 ◽  
Vol 118 (3) ◽  
pp. 341 ◽  
Author(s):  
Lynda A. Randa ◽  
John A. Yunger
Keyword(s):  
Canis Latrans ◽  
Prey Availability ◽  
Canopy Cover ◽  
Ground Cover ◽  
Heterogeneous Environment ◽  
Visitation Rates ◽  
Foliage Density ◽  
Grassland Habitats ◽  
The Relationship ◽  
Habitat Variables

We investigated the effects of local prey fluctuations and habitat variables on the scent station visitation rates of the Coyote (Canis latrans) in northern Illinois within a heterogeneous environment. Availability of small mammalian prey was assessed by monthly mark-recapture sampling and visual counts conducted along three, 192-m transects in each of seven habitats that ranged from grassland to wooded sites. Habitat metrics, which included foliage density, ground cover, and canopy cover, were also collected for the same seven habitats. Visitation rates of Coyotes were determined from scent station lines parallel to the small mammal trapping transects. A multiple regression analysis indicated that Coyote visitation rates across the study site were influenced positively by vole (Microtus spp.) abundance and negatively by canopy cover. When Coyote visitation rates were regressed on vole abundance for only the habitats in which voles occurred, the relationship was not significant. This may be attributed to the general avoidance of wooded areas by Coyotes. Coyotes did, however, respond to experimentallyinduced abundant patches of Peromyscus. These findings suggest Coyotes selectively use grassland habitats within a heterogeneous environment and may modify their use according to prey availability.

Structure and composition of unmanaged riparian forests in the coastal mountains of Oregon, U.S.A.

1999 ◽  
Vol 29 (10) ◽  
pp. 1557-1573 ◽  
Author(s):  
Robert J Pabst ◽  
Thomas A Spies
Keyword(s):  
Spatial Scales ◽  
Canopy Cover ◽  
Basal Area ◽  
Tree Regeneration ◽  
Riparian Forests ◽  
Stream Order ◽  
Third Order ◽  
First Order ◽  
Hardwood Tree ◽  
Stand Attributes

We characterized the structure and composition of unmanaged riparian forests in three river basins in Oregon's coastal mountains. Our objective was to evaluate stand attributes at three spatial scales: streamside (site), drainage network (stream order), and basin (subregion). Data on basal area, species composition, snag density, canopy cover, and tree regeneration were collected along transects at 124 sites. Conifer basal area increased with distance from stream, a trend similar among subregions, and was highest at sites along first-order streams. Hardwood basal area was relatively constant with distance from stream and was proportionally higher at sites along second- and third-order streams than at sites along first-order streams. Conifer and hardwood tree regeneration occurred infrequently and varied by topographic position, stream order, and subregion. Conifer regeneration was associated with basal area of shade-tolerant conifers and appeared to be limited by shrub competition. The unmanaged forests we studied were characterized by a patchy mosaic of structure and composition. Hardwoods and shrubs were major components of the near-stream environment in these forests, whereas dominance of conifers was limited to hillslopes. It appears that fine-scale patterns associated with proximity to the stream are influenced by coarser scale factors such as valley-floor width and climate.

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