In the dry eucalypt forests of north-eastern New South Wales, Australia, cattle grazing occurs at low intensities and is accompanied by frequent low-intensity burning. This study investigated the combined effects of this management practice on the ground-dwelling and arboreal (low vegetation) spider assemblages. Spiders were sampled at 49 sites representing a range of grazing intensities, using pitfall trapping, litter extraction and sweep sampling. A total of 237 spider morphospecies from 37 families were collected using this composite sampling strategy. The abundance, richness, composition and structure of spider assemblages in grazed and ungrazed forest sites were compared and related to a range of environmental variables. Spider assemblages responded to a range of environmental factors at the landscape, habitat and microhabitat scales. Forest type, spatial relationships and habitat variability at the site scale were more important in determining spider assemblages than localized low-intensity grazing and burning. However, it is possible that a threshold intensity of grazing may exist, above which spiders respond to grazing and burning. Although low-intensity grazing and burning may not affect spider assemblages below a threshold stocking rate, that stocking rate has yet to be established.
The summit of Mt Gower, Lord Howe Island (31 �33'S, 159�05'E), is a small area of 27 ha supporting mossy cloud forest. This study describes patterns in the floristic composition and structure of the vegetation of the summit, in relation to a range of environmental variables. A total of 42 vascular plant species was recorded, 86% of which are endemic to Lord Howe Island, and 17% of which are found only on the summit and upper slopes of Mt Gower and adjacent Mt Lidgbird. A complete species list for Mt Gower Is presented, including species from the present survey and all previously recorded species. The composition of the vegetation differed in gullies and on ridges, reflecting differences in substrate rockiness and soil moisture, and was also influenced by the number of bird burrows and aspect. The summit of Mt Gower is of high conservation significance, due to the restrIcted distribution of the habitat type it represents, its relatively undisturbed state and high levels of endemism. Potential threats to the summit vegetation include the impacts of climate change, seed predation by introduced rats, and the introduction of weed species and exotic pathogens such as Phytophthora cinnamomi.
To understand local and regional changes in Neotropical migrant songbird populations it is important to determine whether forest-breeders can use and persist in the dynamic, variegated landscapes created by modern forestry practices. We made detailed observations of a species classified as a mature-forest specialist, the black-throated blue warbler (Dendroica caerulescens), adjacent to clearcut edges and in intact forest in a large industrial forest landscape. We measured reproductive success, habitat use, resource abundance, the potential for inter- and intra-specific competition, and predator densities. Unlike most studies of edge effects, our study showed both positive and negative impacts of associations with edges. We recorded a lower density of potential avian competitors within intact forest, as well as a higher proportion of older male black-throated blue warblers at interior forest sites. In addition, proportionally more fledglings were observed in intact forest. However, males at edge sites had higher pairing success and edges had higher understory density (which is positively associated with reproductive success in other studies), evidence of higher abundance of their primary food source and lower densities of diurnal egg and nestling predators. The net result of these mixed patterns is that males gaining a territory at edge or interior sites appeared to have similar probabilities of producing fledglings.
The coastal areas of Florida, United States, are exposed to increasing risk of flooding due to sea level rise as well as severe hurricanes. Florida regulations suggest constructing stormwater retention ponds as an option to retain excess runoff generated by the increased impervious area and to protect the environment by reducing pollutants from new developments. Groundwater level rise can significantly lower the soil storage capacity and infiltration at retention ponds, in turn, reducing the pond's capacity to capture consecutive storms due to longer pond volume recovery time. Partial groundwater inundation can affect retention ponds' ability to decrease peak flow rates and keep the post-development outflow lower than or equal to pre-development conditions. In this paper, the reliability and performance of a retention pond near Tampa Bay, Florida, was evaluated under sea level rise conditions. An integrated surface water and groundwater model was developed, and the groundwater table was projected for future conditions as a function of sea level rise. The results showed that sea level rise could increase the seasonal high water elevation of the retention pond up to 40 cm by mid-21st century. This increase lowered the reliability of the retention pond by about 45%. The pond failed to recover the designed treatment volume within required 72 h because of the high groundwater table, increasing the risk of pollutant discharge. Furthermore, the peak flow and volume of runoff significantly increased under sea level rise and associated groundwater table rise conditions. The study results suggest that it is imperative to consider future sea level rise conditions in stormwater design in low-lying coastal areas of Florida and around the world to prevent poor pond performance and increased risk of flooding in the future.Most of the studies on climate change and flooding issues have addressed anthropogenic changes of rainfall intensity and frequency as well as land-use changes due to development and urbanization [8][9][10]. These changes substantially alter the peak flow, volume, and duration of flooding and exacerbate domestic inundation areas [11]. In addition to impacts due to rainfall and land-use changes, there is a significant marine flooding risk to highly-populated low-lying cities in coastal areas, including major economic centers such as London, New York, Shanghai, and Mumbai [12]. Globally, it is estimated that more than 20 million people live below the normal high tide elevation and more than 200 million people are under threat of extreme sea level events caused by storms [12]. The United States National Oceanic and Atmospheric Administration (NOAA) reports that about 3.2 billion people worldwide live and work within 200 km of a coastline [13,14], which can be adversely affected by SLR-related closure of access roads and reduced functionality of other infrastructure.In the United States, the state of Florida ranked 3rd for the number of National Flood Insurance Program (NFIP) claims in the last four decades [15]. T...
Successful cell division relies on the timely removal of key cell cycle proteins such as securin. Securin inhibits separase, which cleaves the cohesin rings holding chromosomes together. Securin must be depleted before anaphase to ensure chromosome segregation occurs with anaphase. Here we find that in meiosis I, mouse oocytes contain an excess of securin over separase. We reveal a mechanism that promotes excess securin destruction in prometaphase I. Importantly, this mechanism relies on two phenylalanine residues within the separase-interacting segment (SIS) of securin that are only exposed when securin is not bound to separase. We suggest that these residues facilitate the removal of non-separase-bound securin ahead of metaphase, as inhibiting this period of destruction by mutating both residues causes the majority of oocytes to arrest in meiosis I. We further propose that cellular securin levels exceed the amount an oocyte is capable of removing in metaphase alone, such that the prometaphase destruction mechanism identified here is essential for correct meiotic progression in mouse oocytes.
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