Global no net loss of natural ecosystems

A global goal of no net loss of natural ecosystems or better has recently been proposed, but such a goal would require equitable translation to country-level contributions. Given the wide variation in ecosystem depletion, these could vary from net gain (for countries where restoration is needed), to managed net loss (in rare circumstances where natural ecosystems remain extensive and human development imperative is greatest). National contributions and international support for implementation also must consider non-area targets factors such as the capacity to conserve and the imperative for human development

Averting biodiversity collapse in tropical forest protected areas

The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon¹⁻³. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses⁴⁻⁹. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.Keywords: Ecology, Environmental scienc

Seasonal variation in hornbill abundance in a West African national park detected using analysis of acoustic recordings

Distance sampling, line transects and radio-tracking have been used previously to estimate population abundances and movements of hornbills. We used a large dataset of audio recordings made over 10 years to estimate seasonal variation in abundance of three species: Black-casqued Hornbill Ceratogymna atrata, Yellow-casqued Hornbill C. elata and Brown-cheeked Hornbill Bycanistes cylindricus, in Taï National Park, Côte d'Ivoire. The latter two species are Near Threatened. Recordings of hornbill wing-beats were used to control for potential seasonal variation in call production. Yellow- and Black-casqued Hornbill calls were 10 times as abundant from July to February as they were from March to June. Brown-cheeked Hornbills showed a similar trend, but less pronounced. From these data we concluded that large numbers of Yellow- and Black-casqued Hornbills had left the Taï National Park during this period. The significance of these findings is discussed in relation to the fragmentation and regeneration of the Upper Guinea forests and the relatively small size of the remaining forest habitat in the region. Les taux d'abondance et de mouvement des populations de calaos étaient auparavant estimés par un échantillonnage et des analyses sur le logiciel Distance, des transects linéaires et des repérages télémétriques. Nous avons eu recours è un grand ensemble d'enregistrements audio effectués sur plus de 10 ans afin d'estimer la variation saisonniàre de l'abondance de trois espàces rencontrées dans le Parc National de Taï, en Côte d'Ivoire : le Grand Calao è Casque Noir Ceratogymna atrata, le Grand Calao è Casque Jaune Ceratogymna elata et le Calao è Joues Brunes Bycanistes cylindricus. Ces deux derniàres espàces sont aujourd'hui considérées comme presque menacées. Nous avons procédé è des enregistrements de battements d'ailes pour tester une potentielle variation saisonniàre de la production des cris. Les cris des Grands Calaos è Casque Jaune et è Casque Noir étaient dix fois plus abondants entre juillet et février qu'entre mars et juin. En revanche, les Calaos è Joues Brunes n'ont présenté qu'une petite variation du taux d'abondance entre ces deux périodes. D'apràs ces données, nous avons conclu qu'un grand nombre de Calaos è Casque Jaune et è Casque Noir quittent le Parc National de Taï entre mars et juin. La signification de ces découvertes est discutée en tenant compte de la fragmentation et de la régénération des forêts de Haute Guinée ainsi que de la dimension relativement petite de l'habitat forestier subsistant dans cette région