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Amphibian Declines
This benchmark volume documents in comprehensive detail a major environmental crisis: rapidly declining amphibian populations and the disturbing developmental problems that are increasingly prevalent within many amphibian species. Horror stories on this topic have been featured in the scientific and popular press over the past fifteen years, invariably asking what amphibian declines are telling us about the state of the environment. Are declines harbingers of devastated ecosystems or simply weird reflections of a peculiar amphibian world? This compendium—presenting new data, reviews of current literature, and comprehensive species accounts—reinforces what scientists have begun to suspect, that amphibians are a lens through which the state of the environment can be viewed more clearly. And, that the view is alarming and presages serious concerns for all life, including that of our own species. The first part of this work consists of more than fifty essays covering topics from the causes of declines to conservation, surveys and monitoring, and education. The second part consists of species accounts describing the life history and natural history of every known amphibian species in the United States.
eBook
Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines
The population extinction pulse we describe here shows, from a quantitative viewpoint, that Earth’s sixth mass extinction is more severe than perceived when looking exclusively at species extinctions. Therefore, humanity needs to address anthropogenic population extirpation and decimation immediately. That conclusion is based on analyses of the numbers and degrees of range contraction (indicative of population shrinkage and/or population extinctions according to the International Union for Conservation of Nature) using a sample of 27,600 vertebrate species, and on a more detailed analysis documenting the population extinctions between 1900 and 2015 in 177 mammal species. We find that the rate of population loss in terrestrial vertebrates is extremely high—even in “species of low concern.” In our sample, comprising nearly half of known vertebrate species, 32% (8,851/27,600) are decreasing; that is, they have decreased in population size and range. In the 177 mammals for which we have detailed data, all have lost 30% or more of their geographic ranges and more than 40% of the species have experienced severe population declines (>80% range shrinkage). Our data indicate that beyond global species extinctions Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. We describe this as a “biological annihilation” to highlight the current magnitude of Earth’s ongoing sixth major extinction event.
Journal Article
Urban Shrinkage and Depopulation Dynamics for Sustainable Urban Governance: The Case of Guadalajara
This analysis has the objective of addressing the shrinkage of the Municipality of Guadalajara in the state of Jalisco, México treated here as the counterpart of suburban expansion, which has been caused mainly by the depopulation the city and determines a tendency that defines the dynamics of the great contemporary metropolis in terms of urban sustainable governance. The methodology used consisted of tours to neighborhoods and communities, the observation of structure and the opinion of qualified informants, in addition to the review of documents of municipal government institutions and publications in the local press. The analysis concludes that the great challenges of the policy based on sustainable urban governance of territorial distribution of the population to reverse the depopulation and shrinkage of the municipality of Guadalajara are to achieve a balance of the same within the territory in accordance with a sustainable territorial order, and take advantage of the competitive advantages that the city offers, framed so much in the local economy as a state.
Journal Article
Climate tipping points - too risky to bet against
The growing threat of abrupt and irreversible climate changes must compel political and economic action on emissions.
Journal Article
The diversity of North American shrinking cities
Demographically and economically, there is an ongoing global shift that has resulted in the uneven development and distribution of monetary, human and knowledge capital. This paper first examines and consolidates economic, social and urban theories of growth and decline and demonstrates how globalisation has conceptually shifted the spatial scale and trajectory of urban change theories. The examination of the population trajectories of the 100 largest American cities from 1980 to 2010 demonstrates that the majority either grew or shrank continuously. This trend counters early cyclical models and supports the argument that globalisation has altered population trajectories. Second, conceptualisations of urban shrinkage trajectories are reviewed and a two-dimensional trajectory typology encompassing both economic and demographic change is presented. The diversity of urban shrinkage experiences is demonstrated through the application of the typology to the 20 largest shrinking American cities, 12 of which experienced overall population loss and simultaneous economic growth.
在人口和经济层面，一项持续的全球转变导致了货币资本、人力资本和知识资本的不均衡 发展和分配。本文首先审视并统合了关于增长和衰退的经济、社会及城市理论，并证明了 全球化如何在概念层面改变了城市变革理论的空间尺度和轨迹。对美国100个大城市从1980到2010年的人口变化轨迹考查证明，大多数城市持续增长或持续衰退。这一趋势反 早期的周期循环模式，支持以下论点：全球化改变了人口变化轨迹。其次，我们考核了城 市收缩轨迹的概念表述，并提出了一种涵盖经济和人口变化的二维轨迹类型学。通过将该 类型学应用于美国前20大收缩城市（其中12个出现了总体人口收缩与经济增长同步发生 的现象），我们证明了城市收缩经验的多样性。
Journal Article
Butterfly abundance declines over 20 years of systematic monitoring in Ohio, USA
Severe insect declines make headlines, but they are rarely based on systematic monitoring outside of Europe. We estimate the rate of change in total butterfly abundance and the population trends for 81 species using 21 years of systematic monitoring in Ohio, USA. Total abundance is declining at 2% per year, resulting in a cumulative 33% reduction in butterfly abundance. Three times as many species have negative population trends compared to positive trends. The rate of total decline and the proportion of species in decline mirror those documented in three comparable long-term European monitoring programs. Multiple environmental changes such as climate change, habitat degradation, and agricultural practices may contribute to these declines in Ohio and shift the makeup of the butterfly community by benefiting some species over others. Our analysis of life-history traits associated with population trends shows an impact of climate change, as species with northern distributions and fewer annual generations declined more rapidly. However, even common and invasive species associated with human-dominated landscapes are declining, suggesting widespread environmental causes for these trends. Declines in common species, although they may not be close to extinction, will have an outsized impact on the ecosystem services provided by insects. These results from the most extensive, systematic insect monitoring program in North America demonstrate an ongoing defaunation in butterflies that on an annual scale might be imperceptible, but cumulatively has reduced butterfly numbers by a third over 20 years.
Journal Article
Pollination by hoverflies in the Anthropocene
Pollinator declines, changes in land use and climate-induced shifts in phenology have the potential to seriously affect ecosystem function and food security by disrupting pollination services provided by insects. Much of the current research focuses on bees, or groups other insects together as 'non-bee pollinators', obscuring the relative contribution of this diverse group of organisms. Prominent among the 'non-bee pollinators' are the hoverflies, known to visit at least 72% of global food crops, which we estimate to be worth around US$300 billion per year, together with over 70% of animal pollinated wildflowers. In addition, hoverflies provide ecosystem functions not seen in bees, such as crop protection from pests, recycling of organic matter and long-distance pollen transfer. Migratory species, in particular, can be hugely abundant and unlike many insect pollinators, do not yet appear to be in serious decline. In this review, we contrast the roles of hoverflies and bees as pollinators, discuss the need for research and monitoring of different pollinator responses to anthropogenic change and examine emerging research into large populations of migratory hoverflies, the threats they face and how they might be used to improve sustainable agriculture.
Journal Article