Suchergebnisse

The distribution of species on islands -- Patterns or fantasies? -- Species co-occurrences -- The night sky effect -- Patterns in nature -- Finding the null -- What this book is about -- How this book is organized -- Diamond's assembly rules -- Robert Macarthur, 1930-1972 -- Special islands and their birds -- What is a checkerboard distribution? -- Incidence -- The theoretical context -- The cuckoo doves -- Patchy distributions -- The response of Connor and Simberloff -- The backlash -- How likely are checkerboards? -- Prior expectations -- The analysis of Vanuatu -- A technical interlude -- How to incorporate constraints into incidence matrices -- Definitions and notation -- The numbers of null matrices and the effect of constraints -- The hypergeometric distribution -- The three ecological constraints proposed by Connor and Simberloff in their studies of birds and bats on islands -- Incidence -- Why constraints? and what does "representative" mean? -- How to fill the sample null space -- Null space creation algorithms -- Creating a uniform random sample null space -- The trial-swap algorithm -- How to characterize incidence matrices -- Then you need a metric -- The metric of Connor and Simberloff -- Wright and Biehl -- Harvey et al.'s (1983) review of null models in ecology -- Stone and Roberts (1990, 1992) and Roberts and Stone -- Why ensemble metrics fail: an example -- Reanalysis and extensions -- Vanuatu and the Galapagos -- The birds of Vanuatu -- The birds of the Galapagos -- The birds of the Bismarck and Solomon islands -- The issue of superspecies -- The patterns -- Taxonomic sieving and incidence effects -- Which genera develop checkerboards? -- Caveats -- When the incidences do not overlap -- Coda -- Species along a gradient -- The herptofauna of Mount Kupe, Cameroon -- Why do the results differ from previous results? -- The second question: do species form distinct communities? -- Applications to food webs: nestedness and reciprocal specialization -- Nestedness -- Groupings of species interactions -- Coda -- Macarthur's original vision -- The patterns themselves -- The need for null hypotheses

It is theoretically possible to protect large fractions of species in relatively small regions. For plants, 85% of species occur entirely within just over a third of the Earth's land surface, carefully optimized to maximize the species captured. Well-known vertebrate taxa show similar patterns. Protecting half of Earth might not be necessary, but would it be sufficient given the current trends of protection? The predilection of national governments is to protect areas that are "wild," that is, typically remote, cold, or arid. Unfortunately, those areas often hold relatively few species. Wild places likely afford the easier opportunities for the future expansion of protected areas, with the expansion into human-dominated landscapes the greater challenge. We identify regions that are not currently protected, but that are wild, and consider which of them hold substantial numbers of especially small-ranged vertebrate species. We assess how successful the strategy of protecting the wilder half of Earth might be in conserving biodiversity. It is far from sufficient. (Protecting large wild places for reasons other than biodiversity protection, such as carbon sequestration and other ecosystem services, might still have importance.) Unexpectedly, we also show that, despite the bias in establishing large protected areas in wild places to date, numerous small protected areas are in biodiverse places. They at least partially protect significant fractions of especially small-ranged species. So, while a preoccupation with protecting large areas for the sake of getting half of Earth might achieve little for biodiversity, there is more progress in protecting high-biodiversity areas than currently appreciated. Continuing to prioritize the right parts of Earth, not just the total area protected, is what matters for biodiversity.

Palm oil is the most widely traded vegetable oil globally, with demand projected to increase substantially in the future. Almost all oil palm grows in areas that were once tropical moist forests, some of them quite recently. The conversion to date, and future expansion, threatens biodiversity and increases greenhouse gas emissions. Today, consumer pressure is pushing companies toward deforestation-free sources of palm oil. To guide interventions aimed at reducing tropical deforestation due to oil palm, we analysed recent expansions and modelled likely future ones. We assessed sample areas to find where oil palm plantations have recently replaced forests in 20 countries, using a combination of high-resolution imagery from Google Earth and Landsat. We then compared these trends to countrywide trends in FAO data for oil palm planted area. Finally, we assessed which forests have high agricultural suitability for future oil palm development, which we refer to as vulnerable forests, and identified critical areas for biodiversity that oil palm expansion threatens. Our analysis reveals regional trends in deforestation associated with oil palm agriculture. In Southeast Asia, 45% of sampled oil palm plantations came from areas that were forests in 1989. For South America, the percentage was 31%. By contrast, in Mesoamerica and Africa, we observed only 2% and 7% of oil palm plantations coming from areas that were forest in 1989. The largest areas of vulnerable forest are in Africa and South America. Vulnerable forests in all four regions of production contain globally high concentrations of mammal and bird species at risk of extinction. However, priority areas for biodiversity conservation differ based on taxa and criteria used. Government regulation and voluntary market interventions can help incentivize the expansion of oil palm plantations in ways that protect biodiversity-rich ecosystems.

Terrestrial Mammal Conservation provides a thorough summary of the available scientific evidence of what is known, or not known, about the effectiveness of all of the conservation actions for wild terrestrial mammals across the world (excluding bats and primates, which are covered in separate synopses). Actions are organized into categories based on the International Union for Conservation of Nature classifications of direct threats and conservation actions. Over the course of fifteen chapters, the authors consider interventions as wide ranging as creating uncultivated margins around fields, prescribed burning, setting hunting quotas and removing non-native mammals.This book is written in an accessible style and is designed to be an invaluable resource for anyone concerned with the practical conservation of terrestrial mammals.The authors consulted an international group of terrestrial mammal experts and conservationists to produce this synopsis. Funding was provided by the MAVA Foundation, Arcadia and National Geographic Big Cats Initiative.Terrestrial Mammal Conservation is the seventeenth publication in the Conservation Evidence Series, linked to the online resource www.ConservationEvidence.com. Conservation Evidence Synopses are designed to promote a more evidence-based approach to biodiversity conservation. Others in the series include Bat Conservation, Primate Conservation, Bird Conservation and Forest Conservation and more are in preparation. Expert assessment of the evidence summarised within synopses is provided online and within the annual publication What Works in Conservation.

Assessing the numbers and distribution of threatened species is a central challenge in conservation, often made difficult because the species of concern are rare and elusive. For some predators, this may be compounded by their being sparsely distributed over large areas. Such is the case with the cheetah Acinonyx jubatus. The IUCN Red List process solicits comments, is democratic, transparent, widely-used, and has recently assessed the species. Here, we present additional methods to that process and provide quantitative approaches that may afford greater detail and a benchmark against which to compare future assessments. The cheetah poses challenges, but also affords unique opportunities. It is photogenic, allowing the compilation of thousands of crowd-sourced data. It is also persecuted for killing livestock, enabling estimation of local population densities from the numbers persecuted. Documented instances of persecution in areas with known human and livestock density mean that these data can provide an estimate of where the species may or may not occur in areas without observational data. Compilations of extensive telemetry data coupled with nearly 20,000 additional observations from 39 sources show that free-ranging cheetahs were present across approximately 789,700 km2 of Namibia, Botswana, South Africa, and Zimbabwe (56%, 22%, 12% and 10% respectively) from 2010 to 2016, with an estimated adult population of 3,577 animals. We identified a further 742,800 km2 of potential cheetah habitat within the study region with low human and livestock densities, where another ∼3,250 cheetahs may occur. Unlike many previous estimates, we make the data available and provide explicit information on exactly where cheetahs occur, or are unlikely to occur. We stress the value of gathering data from public sources though these data were mostly from well-visited protected areas. There is a contiguous, transboundary population of cheetah in southern Africa, known to be the largest in the world. We suggest that this population is more threatened than believed due to the concentration of about 55% of free-ranging individuals in two ecoregions. This area overlaps with commercial farmland with high persecution risk; adult cheetahs were removed at the rate of 0.3 individuals per 100 km2 per year. Our population estimate for confirmed cheetah presence areas is 11% lower than the IUCN's current assessment for the same region, lending additional support to the recent call for the up-listing of this species from vulnerable to endangered status.

The classic papers that laid the foundations of modern ecology alongside commentaries by noted ecologists. The period of 1970 to 1995 was a time of tremendous change in all areas of ecology—from an increased rigor for experimental design and analysis to the reevaluation of paradigms, new models for understanding, and theoretical advances. Edited by ecologists Thomas E. Miller and Joseph Travis, Foundations of Ecology II includes facsimiles of forty-six papers from this period alongside expert commentaries that discuss a total of fifty-three key studies, addressing topics of diversity, predation, complexity, competition, coexistence, extinction, productivity, resources, distribution, abundance, and conservation. The result is more than a catalog of historic firsts; this book offers diverse perspectives on the foundational papers that led to today's ecological work. Like this book's 1991 predecessor, Foundations of Ecology edited by Leslie A. Real and James H. Brown, Foundations of Ecology II promises to be the essential primer for graduate students and practicing ecologists for decades to come