scholarly journals Threatened species in a threatened ecosystem: the conservation status of four Solanum species in the face of ongoing habitat loss

Oryx ◽  
2019 ◽  
Vol 53 (3) ◽  
pp. 439-449 ◽  
Author(s):  
Roderick J. Fensham ◽  
Jason Halford ◽  
Chris Hansen ◽  
Boris Laffineur ◽  
Billie Williams
Keyword(s):  
Habitat Loss ◽  
Conservation Status ◽  
Strong Association ◽  
Solanum Species ◽  
Individual Plant ◽  
Exotic Grasses ◽  
Tomato Species ◽  
The Face ◽  
Plant Densities ◽  
Exotic Grass

AbstractPlant biodiversity is threatened by habitat loss, fragmentation and invasion by exotic species, but the effects of these disturbances on individual plant species are rarely quantified. Since the 1950s, brigalow Acacia harpophylla forests in Australia have been extensively cleared and converted to pastures dominated by exotic grasses. Here we assess the habitat requirements, population numbers and threats for four poorly known bush tomato species, Solanum adenophorum, Solanum dissectum, Solanum elachophyllum and Solanum johnsonianum. Herbarium records and surveys demonstrated a strong association of all four species with brigalow habitat, although S. elachophyllum also occurred in other habitat. We derived historical and current population estimates from plant densities at current sites and the area of mapped brigalow habitat. Density estimates are imprecise because the survey data vary greatly, but the assessment indicates the populations of all four species have declined > 93%. Solanum dissectum and S. johnsonianum did not persist in cleared brigalow habitat, whereas S. adenophorum and S. elachophyllum had some capacity to persist in clearings. None of the species occur where the exotic grass cover is > 40%. Between 27% and 57% of the records of the four species are in brigalow remnants with a high edge-to-area ratio or open canopy (< 50% cover), making them highly vulnerable to invasive grasses. We recommend the categorization of S. dissectum and S. johnsonianum as Critically Endangered, S. adenophorum as Vulnerable and S. elachophyllum as Near Threatened.

Density and activity patterns of ocelot populations in Yasuní National Park, Ecuador

Mammalia ◽  
2016 ◽  
Vol 80 (4) ◽  
Author(s):  
Julia Salvador ◽  
Santiago Espinosa
Keyword(s):  
Population Density ◽  
Habitat Loss ◽  
National Park ◽  
Conservation Status ◽  
Activity Patterns ◽  
Camera Trap ◽  
Oil Extraction ◽  
Density Estimates ◽  
Yasuni National Park ◽  
Ecuadorian Amazon

AbstractOcelots were historically hunted for their skins but habitat loss is now their most serious threat, causing rapid declines in populations throughout their range. Ocelot abundance has been estimated for various locations across the Neotropics, but we still lack this information from some countries, including Ecuador. Knowing whether ocelot abundance is increasing or decreasing is important to assess the conservation status of this species and the conditions of its habitats in the Ecuadorian Amazon and in the region. To determine whether ocelot abundance and its behavior are affected by human-related activities, camera-trap surveys were carried out in two localities of Yasuní National Park (YNP), one that has experienced hunting, oil extraction, and roads (Maxus Road) and one that is largely unaffected by these activities (Lorocachi). During the survey, 35 and 36 individual ocelots were photographed in Maxus Road and Lorocachi, respectively. Population density estimates were similar for both localities, ranging from 0.31 (SE±6) to 0.85 (SE±17) ocelots/km

Persistence of Plants and Pollinators in the Face of Habitat Loss

2015 ◽  
pp. 201-257 ◽  
Author(s):  
Julia Astegiano ◽  
Paulo R. Guimarães ◽  
Pierre-Olivier Cheptou ◽  
Mariana Morais Vidal ◽  
Camila Yumi Mandai ◽  
...  
Keyword(s):  
Habitat Loss ◽  
The Face

scholarly journals Increasing population density reduces soybean yield components and productivity

2021 ◽  
Vol 37 ◽  
pp. e37042
Author(s):  
Marcelo De Almeida Silva ◽  
Ana Carolina De Santana Soares ◽  
Melina Rodrigues Alves Carnietto ◽  
Alexandrius De Moraes Barbosa
Keyword(s):  
Grain Yield ◽  
Yield Components ◽  
Spatial Arrangement ◽  
Plant Population ◽  
Row Spacing ◽  
Individual Plant ◽  
Growth Type ◽  
Soybean Yield ◽  
Plant Densities ◽  
Plant Yields

Studies addressing the interaction of different spatial arrangement in soybean are needed in order to achieve management that leads to higher grain yield associated with rational seed use. The objective of this work was to evaluate the yield components and productivity of an undetermined growth type soybean as a function of different row spacing and plant densities. The treatments consisted of three row spaces (0.25, 0.35 and 0.45 m) and three plant population densities (30, 40 and 50 plants/m²). There was no interaction of row spaces and plant population on soybean yield. Regarding the overall spacing average, the grain yield of the population of 30/m² plants was higher than the productivity of the populations of 40 and 50/m² plants. The largest populations reduce plant sizes due to greater competition between plants. In addition, smaller populations promote higher individual plant yields due to the increase components of the production. This characteristic is defined as the ability of the plant to change its morphology and yield components in order to adapt to the conditions imposed by the spatial arrangement.

scholarly journals Carnivores (Mammalia) from areas of Nearctic–Neotropical transition in Puebla, central Mexico: presence, distribution, and conservation

Check List ◽  
2016 ◽  
Vol 12 (1) ◽  
pp. 1833 ◽  
Author(s):  
Osvaldo Eric Ramírez-Bravo ◽  
Lorna Hernandez-Santin
Keyword(s):  
Habitat Loss ◽  
Conservation Status ◽  
The State ◽  
Lynx Rufus ◽  
Risk Category ◽  
Central Mexico ◽  
Leopardus Pardalis ◽  
Lethal Control ◽  
Hunting Pressure ◽  
Carnivore Species

The Nearctic and Neotropical realms converge in central Mexico, where many areas have not been adequately characterized. Our objective was to revise the distribution and conservation status of carnivores in the state of Puebla, central Mexico. Between September 2008 and January 2011, we conducted interviews and fieldwork on seven previously selected areas. We complemented our data with bibliographical research. We obtained 733 records for 21 species, representing 63% of the carnivores reported for Mexico. We expanded known ranges of three species: Ocelot (Leopardus pardalis), Bobcat (Lynx rufus), and Tropical Ringtail (Bassariscus sumichastrii). Fifty percent of the carnivore species we recorded in Puebla are considered under some risk category. We found that carnivores in our study area are vulnerable to hunting pressure, human-carnivore conflicts that result in lethal control practices, and extensive habitat loss.

Pasture-scale vegetation predicts Dickcissel nest-site selection and success in native and exotic grass pastures

The Condor ◽  
2019 ◽  
Vol 121 (3) ◽  
Author(s):  
Adrian P Monroe ◽  
L Wes Burger ◽  
James A Martin
Keyword(s):  
Site Selection ◽  
Nest Site ◽  
Nest Survival ◽  
Nest Site Selection ◽  
Schizachyrium Scoparium ◽  
Beef Production ◽  
Exotic Grasses ◽  
Nest Sites ◽  
Exotic Grass ◽  
Tall Structure

Abstract Exotic grasses such as bermudagrass (Cynodon dactylon) and tall fescue (Schedonorus arundinaceus) are widely established across the southeastern United States as livestock forage, but their structure and management can limit avian reproductive success. Native warm-season grasses (NWSG) are promoted as sustainable forage alternatives. To examine nesting suitability for tall structure specialists such as Dickcissels (Spiza americana) we established an operational-scale study in northeastern Mississippi, USA, with 4 treatments along a gradient of beef production intensity. Treatments included grazed exotic forages, 2 grazed NWSG treatments including Indiangrass (Sorghastrum nutans) monoculture and NWSG polyculture of Indiangrass, little bluestem (Schizachyrium scoparium), and big bluestem (Andropogon gerardii), and an ungrazed NWSG polyculture treatment. We monitored 208 Dickcissel nests in 2011 and 2012 to evaluate effects of treatment, vegetation structure, fire ants (Solenopsis spp.), and arthropod prey biomass on nest-site selection and nest survival. Survival rates varied among treatments and increased with pasture-scale visual obstruction reading (VOR), being lowest among grazed exotic grass, intermediate in grazed NWSG, and highest in ungrazed NWSG. Although Dickcissels selected nest sites with greater VOR, we found little support for effects of nest-site vegetation on survival. However, nest survival was lower for nests in shrubs that also occurred in pastures with greater shrub cover, and selection for shrubs declined as pasture-scale VOR increased, suggesting a functional response in selection. We found little support for food availability influencing nest survival. These results suggest NWSG pastures increase Dickcissel nest success through greater pasture-scale VOR by reducing Dickcissel selection of shrubs for nest sites, and possibly by reducing predator efficiency. Incorporating NWSG into beef production systems while maintaining availability of tall vegetation could benefit Dickcissels and other tall structure specialists.

The effect of plant density on populations of the cabbage root fly (Erioischia brassicae (Bch.)) and the cabbage stem weevil (Ceutorhynchus quadridens (Panz.)) on cauliflowers

1976 ◽  
Vol 66 (1) ◽  
pp. 113-123 ◽  
Author(s):  
S. Finch ◽  
G. Skinner
Keyword(s):  
Plant Density ◽  
Unit Area ◽  
Individual Plant ◽  
Cabbage Root Fly ◽  
Plant Densities ◽  
Equivalent Area ◽  
Concentric Circles ◽  
The Absolute ◽  
Absolute Population

AbstractTo study the effects of plant density on populations of the cabbage root fly (Erioischia brassicae (Bch.) ) and the cabbage stem weevil (Ceutorhynchus quadridens (Panz.)), cauliflowers were planted in 24 concentric circles to achieve spacings of 10–90 cm at 22 plant densities (1·5–83/m2). Some plants were treated with a root drench of chlorfenvinphos. Each week female cabbage root flies laid approximately three times as many eggs per individual plant at the lowest than at the highest plant densities tested. This was equivalent to approximately 350 and 5000 eggs/m2, respectively. The numbers of cabbage root fly pupae produced ranged from 11/m2 at the lowest to 210/m2 at the highest plant density. In the absence of an insecticide, increasing the plant density considerably increased the absolute population of the pest without affecting cauliflower yield. Approximately seven times as many flies were produced per unit area of untreated mini-cauliflowers as from an equivalent area of plants growing at a conventional density. When chlorfenvinphos was not applied, damage by the cabbage stem weevil occurred in 30% and 70% of the plants grown at the lowest and highest densities, respectively.

The design of nature reserves in the face of habitat loss

2017 ◽  
Vol 358 ◽  
pp. 50-58 ◽  
Author(s):  
Haoqi Liu ◽  
Weide Li ◽  
Guanghui Lv
Keyword(s):  
Habitat Loss ◽  
Nature Reserves ◽  
The Face

scholarly journals The conservation status in 1982 of the Aldabra White-throated Rail Dryolimnas cuvieri aldabranus

1993 ◽  
Vol 3 (4) ◽  
pp. 299-305 ◽  
Author(s):  
N. J. Collar
Keyword(s):  
Leaf Litter ◽  
Habitat Loss ◽  
Conservation Status ◽  
World Heritage ◽  
World Heritage Site ◽  
Heritage Site ◽  
Terrestrial Habitats

SummaryThe Aldabra White-throated Rail Dryolimnas cuvieri aldabranus is confined to Middle Island (c. 7,700 birds), lie Polymnie (c. 270) and De aux Cèdres (c. 80) on Aldabra Atoll (now a World Heritage Site) in the Seychelles. It uses all available terrestrial habitats, but chiefly occurs in scrub cover and particularly in the densest types, where leaf-litter (and hence litter fauna) is richest. Its extinction on Assumption, Astove and Cosmoledo is attributable to widespread habitat loss and disturbance, and to human utilization as food; the extent to which rats and cats affect the form, which is flightless, is debatable.

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