Écologie, extinctions…

1. Mégafaune et biomasse aujourd’hui
Déclin des insectes et petits animaux aujourd’hui
Extinctions et déclins de mégafaune depuis le pliocène
Impact de la chasse aux trophées
Sujets d’écologie divers

Mégafaune et biomasse aujourd’hui

Introduced herbivores restore Late Pleistocene ecological functions
Lundgren et al.
PNAS, 2020

Many introduced herbivores restore trait combinations that have the capacity to influence ecosystem processes, such as wildfire and shrub expansion in drylands. Although introduced species have long been a source of contention, our findings indicate that they may, in part, restore ecological functions reflective of the past several million years before widespread human-driven extinctions.

Are we eating the world’s megafauna to extinction?
Ripple et al.
Conservation letters, 2019

Surprisingly, direct harvesting of megafauna for human consumption of meat or body parts is the largest individual threat to each of the classes examined, and a threat for 98% (159/162) of threatened species with threat data available. Therefore, minimizing the direct killing of the world’s largest vertebrates is a priority conservation strategy that might save many of these iconic species and the functions and services they provide.

The biomass distribution on Earth
Bar-On et al.
PNAS 2018

Biomass distribution current

Living Planet Index
WWF, 2018

Living planet index

A continent-wide assessment of the form and intensity of large mammal herbivory in Africa
Hempson et al.
Science, 2015

Hempson 2015 biomass to rainfall

Defaunation in the Anthropocene
Rodolfo Dirzo et al.
Science, 2014

Cliquer pour accéder à Collen_Dirzo%20etal%202014%20Science%20Accepted.pdf


Among terrestrial vertebrates 322 species have become extinct since 1500, while populations of the remaining species show 25% average decline in abundance. Invertebrate patterns are equally dire: 67% of monitored populations show 45% mean abundance decline. Such animal declines will cascade onto ecosystem functioning and human well-being. Much remains unknown about this “Anthropocene defaunation”; these knowledge gaps hinder our capacity to predict and limit defaunation impacts. Clearly, however, defaunation is both a pervasive component of the planet’s sixth mass extinction, and also a major driver of global ecological change.

Dirzo et al. 2014 Defaunation in the anthropocene

Diminution invertébrés depuis 1970

Wildlife comeback in Europe
Deinet et al.
Rewilding Europe, 2013

Cliquer pour accéder à Wildlife-Comeback-in-Europe-the-recovery-of-selected-mammal-and-bird-species.pdf

Harvesting the Biosphere: The Human Impact
Vaclav Smil
Population and development review, 2011

Cliquer pour accéder à PDR37-4.Smil_.pgs613-636.pdf

Smill 2011 biomass evolution

Impacts of Biodiversity Loss on Ocean Ecosystem Services
Worm et al.
Science, 2006

Cliquer pour accéder à AR-024.pdf

Worm et al. 2006

Déclin des insectes et petits animaux aujourd’hui

No net insect abundance and diversity declines across US Long Term Ecological Research sites
Crossley et al.
Nature ecology & evolution, 2020

Some taxa and sites showed decreases in abundance and diversity while others increased or were unchanged, yielding net abundance and biodiversity trends generally indistinguishable from zero. This lack of overall increase or decline was consistent across arthropod feeding groups and was similar for heavily disturbed versus relatively natural sites. The apparent robustness of US arthropod populations is reassuring. Yet, this result does not diminish the need for continued monitoring and could mask subtler changes in species composition that nonetheless endanger insect-provided ecosystem services.

Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances
Van Klink et al.
Science, 2020

Recent case studies showing substantial declines of insect abundances have raised alarm, but how widespread such patterns are remains unclear. We compiled data from 166 long-term surveys of insect assemblages across 1676 sites to investigate trends in insect abundances over time. Overall, we found considerable variation in trends even among adjacent sites but an average decline of terrestrial insect abundance by ~9% per decade and an increase of freshwater insect abundance by ~11% per decade. Both patterns were largely driven by strong trends in North America and some European regions. We found some associations with potential drivers (e.g., land-use drivers), and trends in protected areas tended to be weaker. Our findings provide a more nuanced view of spatiotemporal patterns of insect abundance trends than previously suggested.

Light pollution is a driver of insect declines
Owens et al.
Biological conservation, 2019

Habitat loss, pesticide use, invasive species, and climate change all have likely played a role, but we posit here that artificial light at night (ALAN) is another important—but often overlooked—bringer of the insect apocalypse.

The effect of intensified illuminance and artificial light at night on fitness and susceptibility to abiotic and biotic stressors
Dyllan May et al.
Environmental pollution, 2019

Overall, changes in light conditions, in particular ALAN, significantly impacted an amphibian model in laboratory conditions. This work underscores the importance of considering not only the direct effects of light on fitness metrics but also the indirect effects of light with other abiotic and biotic stressors. Anthropogenic-induced changes to light conditions are expected to continue increasing over time so understanding the diverse consequences of shifting light conditions will be paramount to protecting wildlife populations.

Arthropod decline in grasslands and forests is associated with landscape-level drivers
Seibold et al.
Nature, 2019

In annually sampled grasslands, biomass, abundance and number of species declined by 67%, 78% and 34%, respectively. The decline was consistent across trophic levels and mainly affected rare species; its magnitude was independent of local land-use intensity. However, sites embedded in landscapes with a higher cover of agricultural land showed a stronger temporal decline. In 30 forest sites with annual inventories, biomass and species number—but not abundance—decreased by 41% and 36%, respectively. This was supported by analyses of all forest sites sampled in three-year intervals. The decline affected rare and abundant species, and trends differed across trophic levels. Our results show that there are widespread declines in arthropod biomass, abundance and the number of species across trophic levels. Arthropod declines in forests demonstrate that loss is not restricted to open habitats. Our results suggest that major drivers of arthropod decline act at larger spatial scales, and are (at least for grasslands) associated with agriculture at the landscape level. This implies that policies need to address the landscape scale to mitigate the negative effects of land-use practices.

Evidence for Recent Decline of Arthropods in Germany is Not Yet Robust
Hambler & Henderson, 2019

What has been demonstrated is a decline in the relative activity-abundance of a limited selected set of taxa in a selected period of years. Use of a small number of years to detect trends is statistically problematic, and highly dependent on start and end dates of the time series.

“Insectageddon”: A call for more robust data and rigorous analyses
Thomas et al.
Global change biology, 2019

As members of that subset of the human population who love insects, we have been alarmed by a recent publication reporting their global decline and impending extinction (Sánchez‐Bayo & Wyckhuys, 2019), and the accompanying media furore. Indeed, there has been a growing tide of concern over the magnitude and potential consequences of diminishing insect populations (e.g., Hallmann et al., 2017; Lister & Garcia, 2018). However, we respectfully suggest that accounts of the demise of insects may be slightly exaggerated. Bad things are happening—we agree—but this is not the whole story. We call for hard‐nosed, balanced, and numerical analysis of the changes taking place, and for calm and even‐handed interpretation of the changes, rather than rushing headlong into the hyperbole of impending apocalypse.

Cette publication lie le déclin des coléoptères dans des zones préservées de l’activité humaine du New Hampshire au réchauffement climatique.

Decline in beetle abundance and diversity in an intact temperate forest linked to climate warming
Jennifer E. Harris et al.
Biological conservation, 2019

Beetle capture rate was least when and where climate was warmest. Capture rate was significantly lower in the 2010s when mean daily temperature was about 1.8 °C warmer, and sampling during 2016–2017 at low, mid and high elevations (320, 540, and 810 m asl, respectively) revealed lowest beetle captures at low elevation where climate was warmest. Most importantly, beetle capture rate was significantly lower after winters with less snow cover during the previous winter, indicating that snow cover in northern hardwood forest is essential for sustaining the beetle community. These results imply that additional climate warming might further reduce the abundance and diversity of beetles and other arthropods inhabiting the forest-floor, potentially affecting critical ecosystem processes such as decomposition and carbon storage.

Decline of the North American avifauna*
Rosenberg et al.
Science, 2019

Using multiple and independent monitoring networks, we report population losses across much of the North American avifauna over 48 years, including once common species and from most biomes. Integration of range-wide population trajectories and size estimates indicates a net loss approaching 3 billion birds, or 29% of 1970 abundance. A continent-wide weather radar network also reveals a similarly steep decline in biomass passage of migrating birds over a recent 10-year period.

Declines in insect abundance and diversity : We know enough to act now
Forister et al.
Conservation science and practice, 2019

Recent regional reports and trends in biomonitoring suggest that insects areexperiencing a multicontinental crisis that is apparent as reductions in abundance,diversity, and biomass. Given the centrality of insects to terrestrial ecosystems andthe food chain that supports humans, the importance of addressing these declinescannot be overstated. The scientific community has understandably been focusedon establishing the breadth and depth of the phenomenon and on documenting fac-tors causing insect declines. In parallel with ongoing research, it is now time forthe development of a policy consensus that will allow for a swift societal response.We point out that this response need not wait for full resolution of the many physi-ological, behavioral, and demographic aspects of declining insect populations. Tothese ends, we suggest primary policy goals summarized at scales from nations tofarms to homes.

No Simple Answers for Insect Conservation: Media hype has missed the biggest concern that ecologists and entomologists have about six-legged life: how little we know about it
Manu E. Saunders
American Scientist, 2019

Widespread, consistent insect declines are a real concern. Yet there is little published evidence that worldwide decline of all insects is happening. The aforementioned studies were localized and skewed toward particular taxa. The authors of the Krefeld and Luquillo studies tried not to overextend their results in their journal articles, but the press releases from the lead authors’ institutions, media coverage, and the recent review paper were less cautious. Sanchez-Bayo and Wyckhuys claimed that their review showed that « almost half of the [world’s insect] species are rapidly declining. » Yet their data show declines for only about 2,900 species–a tiny fraction of the estimated 5 million insect species on Earth.
The Krefeld study is based on trap samples from 63 nature reserve sites in Germany, collected over a 27-year period. But more than half the sites were only surveyed once during the study period, and only 26 sites were surveyed in multiple, though not consecutive, years. The lack of repeated sampling at exactly the same locations over a long period of time limits understanding of the true extent of declines across Europe, let alone in the rest of the world. Moreover, biomass is a poor proxy for abundance or species richness.

Worldwide decline of the entomofauna: A review of its drivers
Sanchez-Bayo & Wyckhuys

Biological conservation, 2019

The main drivers of species declines appear to be in order of importance: i) habitat loss and conversion to intensive agriculture and urbanisation; ii) pollution, mainly that by synthetic pesticides and fertilisers; iii) biological factors, including pathogens and introduced species; and iv) climate change. The latter factor is particularly important in tropical regions, but only affects a minority of species in colder climes and mountain settings of temperate zones. A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically-based practices, is urgently needed to slow or reverse current trends, allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide. In addition, effective remediation technologies should be applied to clean polluted waters in both agricultural and urban environments.

Climate-driven declines in arthropod abundance restructure a rainforest food   Bradford C. Lister & Andres Garcia
PNAS, 2018

Cliquer pour accéder à E10397.full.pdf

Analysis of long-term data on canopy arthro-pods and walking sticks taken as part of the Luquillo Long-TermEcological Research program revealed sustained declines in abun-dance over two decades, as well as negative regressions of abun-dance on mean maximum temperatures. We also document paralleldecreases in Luquillo’s insectivorous lizards, frogs, and birds. While ElNiño/Southern Oscillation influences the abundance of forest arthro-pods, climate warming is the major driver of reductions in arthropodabundance, indirectly precipitating a bottom-up trophic cascade andconsequent collapse of the forest food web.

Une réponse à l’article :

Populations are not declining and food webs are not collapsing at the Luquillo Experimental Forest
Willig et al.
PNAS, 2019

Canopy arthropod density does not decline between 1994 and 2009 but does increase significantly with increasing temperature (figures 5 and 6 of Supplementary Materials), even for the 10 most abundant taxa (tables 1 and 2 of Supplementary Materials), which Lister and Garcia claimed to have used (3).

Long-term data do not suggest a simple decline in adult frogs from 1987 to 2017 (figure 7 of Supplementary Materials) but do document an increase in numbers with increasing temperature (figure 8 of Supplementary Materials). Numbers vary in a consistent and nondirectional manner, except for short-term increases after Hurricanes Hugo and Georges, which modified habitat structure

Et une réponse à la réponse :

Reply to Willig et al.: Long-term population trends in the Luquillo Rainforest
Brad Lister and Andres Garcia
PNAS, 2019

Exposure of Insects to Radio-Frequency Electromagnetic Fields from 2 to 120 GHz
Arno Thielens et al.
Nature Scientific Reports, 2018

All insects showed a dependence of the absorbed power on the frequency. All insects showed a general increase in absorbed RF power at and above 6 GHz, in comparison to the absorbed RF power below 6 GHz. Our simulations showed that a shift of 10% of the incident power density to frequencies above 6 GHz would lead to an increase in absorbed power between 3–370%.

Artificially lit surface of Earth at night increasing in radiance and extent
Kyba et al.
Science advances, 2017

A central aim of the “lighting revolution” (the transition to solid-state lighting technology) is decreased energy consumption. This could be undermined by a rebound effect of increased use in response to lowered cost of light. We use the first-ever calibrated satellite radiometer designed for night lights to show that from 2012 to 2016, Earth’s artificially lit outdoor area grew by 2.2% per year, with a total radiance growth of 1.8% per year. Continuously lit areas brightened at a rate of 2.2% per year. Large differences in national growth rates were observed, with lighting remaining stable or decreasing in only a few countries. These data are not consistent with global scale energy reductions but rather indicate increased light pollution, with corresponding negative consequences for flora, fauna, and human well-being.

More than 75 percent decline over 27 years in total flying insect biomass in protected areas
Hallmann et al.
Plos One, 2017

Global declines in insects have sparked wide interest among scientists, politicians, and the general public. Loss of insect diversity and abundance is expected to provoke cascading effects on food webs and to jeopardize ecosystem services. Our understanding of the extent and underlying causes of this decline is based on the abundance of single species or taxonomic groups only, rather than changes in insect biomass which is more relevant for ecological functioning. Here, we used a standardized protocol to measure total insect biomass using Malaise traps, deployed over 27 years in 63 nature protection areas in Germany (96 unique location-year combinations) to infer on the status and trend of local entomofauna. Our analysis estimates a seasonal decline of 76%, and mid-summer decline of 82% in flying insect biomass over the 27 years of study. We show that this decline is apparent regardless of habitat type, while changes in weather, land use, and habitat characteristics cannot explain this overall decline. This yet unrecognized loss of insect biomass must be taken into account in evaluating declines in abundance of species depending on insects as a food source, and ecosystem functioning in the European landscape.

Cette publication suggère que les parasites et les pathogènes sont les responsables directs de la mort d’abeilles domestiques et sauvages, mais que les pesticides, particulièrement les néonicotinoïdes, sont responsables de leur affaiblissement, qui les rend plus sensibles aux parasites.

Are bee diseases linked to pesticides? — A brief review
Sanchez-Bayo et al.
Environment international, 2016

Wild and managed bees have been declining in recent years.
Parasites and pathogens are the main cause of the current bee demise.
Stress agents acting on bees can promote pathogen spread and virulence.
Sublethal doses of immunosuppressive pesticides favour the diffusion of bee diseases.
Pesticides and their interactions contribute to stress-induced colony losses.

The new world atlas of artificial night sky brightness
Falchi et al.
Science advances, 2016

Artificial lights raise night sky luminance, creating the most visible effect of light pollution—artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world’s land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights.

Effects of roads on insects: a review
Muñoz et al.
Biodiversity and conservation, 2015

We found that roads negatively affect the abundance and diversity of insects due to two main factors: (1) the high mortality of some groups when crossing the road, with more impact at higher traffic volumes. (2) The unwillingness of many species to cross a road or live close to it. Roads are major barriers for small or flightless species, although the response varied for flying species. Finally, both experimental and observational evidence support the idea that air pollutants and de-icing salt used for the road maintenance negatively affect insects.

The impact of free-ranging domestic cats on wildlife of the United States
Loss et al.
Nature communication, 2013.

We estimate that free-ranging domestic cats kill 1.3–4.0 billion birds and 6.3–22.3 billion mammals annually. Un-owned cats, as opposed to owned pets, cause the majority of this mortality. Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals.

Long‐term changes in the abundance of flying insects
Shortall et al.
Insect conservation and diversity, 2009

1. For the first time, long‐term changes in total aerial insect biomass have been estimated for a wide area of Southern Britain.

2. Various indices of biomass were created for standardised samples from four of the Rothamsted Insect Survey 12.2 m tall suction traps for the 30 years from 1973 to 2002.

3. There was a significant decline in total biomass at Hereford but not at three other sites: Rothamsted, Starcross and Wye.

4. For the Hereford samples, many insects were identified at least to order level, some to family or species level. These samples were then used to investigate the taxa involved in the decline in biomass at Hereford.

5. The Hereford samples were dominated by large Diptera, particularly Dilophus febrilis, which showed a significant decline in abundance.

6. Changes in agricultural practice that could have contributed to the observed declines are discussed, as are potential implications for farmland birds, with suggestions for further work to investigate both cause and effect.

Extinctions et déclins de mégafaune depuis le pliocène

La section commençant à devenir très volumineuse, elle a gagné une page dédiée.

Impact de la chasse aux trophées

Local perceptions of trophy hunting on communal lands in Namibia
Angula et al.
Biological conservation, 2018

Our results suggest that in Namibia, a trophy hunting ban would be viewed very poorly by conservancy residents, and would seriously weaken their support for wildlife conservation. The imposition of trophy hunting policies by countries far from where rural land managers are conserving wildlife would not only restrict communities’ livelihood options, but may have perverse, negative impacts on wildlife conservation.

Banning Trophy Hunting Will Exacerbate Biodiversity Loss
Di Mimin et al.
Trends in ecology and evolution, 2016

International pressure to ban trophy hunting is increasing. However, we argue that trophy hunting can be an important conservation tool, provided it can be done in a controlled manner to benefit biodiversity conservation and local people. Where political and governance structures are adequate, trophy hunting can help address the ongoing loss of species.

Une réponse :
Does Trophy Hunting Support Biodiversity? A Response to Di Minin
et al.
Ripple et al.
Trends in ecology and evolution, 2016

Di Minin et al. [1] are correct in stating that trophy hunting can increase funding for conservation (this is well known), but they have failed to address the effects of trophy hunting on the suite of mechanisms driving species interactions, plant community dynamics, natural selection, trophic cascades, and ecosystem structure and function. While there are many issues relating to the pros and cons of trophy hunting, we suggest that the ecological and evolutionary discussion should focus on relevant variables and interactions that can be linked to trophy hunting.

Une réponse à la réponse :

Trophy Hunting Does and Will Support Biodiversity: A Reply to Ripple et al.
Mimin et al.
Trends in ecology and evolution, 2016

Conservation or the Moral High Ground: Siding with Bentham or Kant
MacDonald et al.
Conservation letters, 2016

5. Sujets d’écologie divers

Déplacé ici