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Offers a look at how to sustain biodiversity. Report that the coastal forests of Brazil hold the largest number of species at risk of extinction in the Americas; Depletion of the major fish populations worldwide; Increase of endangered and extinct species; Report that areas that have the most extinction include almost all species on islands, mammals in Australia, plants in the southern tip of Africa, and freshwater fish in the Mississippi Basin and East African Lakes; Degradation of tropical forests that hold the most endangered species; Discussion of how to protect areas in developing countries; Importance of alternatives to logging in developing countries; Reference to the book "Perverse Subsidies," by Norman Myers and Jennifer Kent; Uses of the Kyoto carbon-trading system in developing countries; Benefits of ecotourism. INSET: THE LAWS OF BIOGEOGRAPHY.

The article discusses the work of conservation biologists in connecting forest habitats to conserve animals with limited ranges. Topics include the mapping of the geographical ranges of species, research on forest habitat fragments, and species conservation efforts in Brazilian forests. Efforts to conserve birds are described.

Deforestation is a major driver of climate change and the major driver of biodiversity loss. Yet the essential baseline for monitoring forest cover—the global area of forests—remains uncertain despite rapid technological advances and international consensus on conserving target extents of ecosystems. Previous satellite-based estimates of global forest area range from 32.1  ×  106km2to 41.4  ×  106km2. Here, we show that the major reason underlying this discrepancy is ambiguity in the term ‘forest’. Each of the >800 official definitions that are capable of satellite measurement relies on a criterion of percentage tree cover. This criterion may range from >10% to >30% cover under the United Nations Framework Convention on Climate Change. Applying the range to the first global, high-resolution map of percentage tree cover reveals a discrepancy of 19.3  ×  106km2, some 13% of Earth’s land area. The discrepancy within the tropics alone involves a difference of 45.2 Gt C of biomass, valued at US$1 trillion. To more effectively link science and policy to ecosystems, we must now refine forest monitoring, reporting and verification to focus on ecological measurements that are more directly relevant to ecosystem function, to biomass and carbon, and to climate and biodiversity.

ABSTRACT We investigated survival for male, female, and first-year Cape Sable seaside sparrows (Ammodramus maritimus mirabilis, hereafter sparrows), a federally endangered bird restricted to the Florida Everglades, USA. Accurate estimates of survival are critical to improve management decisions and population estimates for this and other threatened species. We used Program MARK to evaluate effects of age, sex, population membership, temporal variation, and ground-water levels on annual survival from mark-recapture data collected across 3 sparrow populations from 1997 to 2007. We found little evidence that annual survival rates differed between the populations or across ground-water levels, but we found high variability between years for both adult and juvenile survival. Our results revealed female sparrows experienced 14–19% lower survival than males. Sparrows experienced much lower survival during their first year of life and were short-lived (2–3 yr). Our results highlight sparrows' susceptibility to population declines and suggest that management actions aimed at increasing survival may be effective for this species' management.

Early studies suggested that simple ecosystems were less stable than complex ones, but later studies came to the opposite conclusion. Confusion arose because of the many different meanings of ‘complexity’ and ‘stability’. Most of the possible questions about the relationship between stability–complexity have not been asked. Those that have yield a variety of answers.

The variability of population densities over time (henceforth called population variability) is one of several meanings of ecological stability1. Here we show that estimates of the variability of population densities increase as we increase the number of years included in their calculation. This result appears for the majority of populations surveyed and over almost all the time intervals over which we calculate the variability. This result has implications for the debate over whether populations have an equilibrium.

This paper considers the effects of different levels of resource predictability on niche widths, competition and diversity in a community of three hummingbird species. Three pairs of hypotheses are tested: whether decreasing predictability (a) increases or decreases niche width, (b) increases or decreases competition and (c) increases or decreases diversity. The results show that complementary increases and decreases in niche width occur with decreasing predictability, while competition and diversity decrease, at least with extreme unpredictability. A model, which assumes the species to have similar resource preferences, and its predictions are examined. The dominant species, Lampornis clemenciae, excludes a subordinate species, Archilochus alexandri, from preferred resources. This defense becomes unprofitable with decreasing predictability and Archilochus invades the resources once vigorously defended by Lampornis. When the spectrum of resources is altered in the direction of decreasing suitability for both species, Lampornis becomes even more specialized and sensitive to the effects of unpredictability. A third species, Eugenes fulgens, steals resources undefended by Lampornis. These characteristics seem to be common to a number of communities in very different taxonomic groups, and characteristic of communities in which species share a common preferred resource. The question of how a community organized with distinct resource preferences responds to decreasing predictability remains open.