Frontiers in Ecology and the Environment最新文献

Managing ecosystems to sequester soil carbon requires a thorough understanding of complex soil processes. Here, we integrate these soil processes through the metaphor of a game—one that moves through multiple dimensions (from macro-aggregates to micropores and clay particles) and scales (from centimeters to nanometers) of the soil. The rules of the game are based on current understanding of soil carbon persistence, which differs from the classic humus concept of molecular complexity. The game's objective is to win points, by keeping “tokens” (plant-derived organic compounds) within the soil organic matter for as long as possible. The game begins when tokens enter different “pool-levels” (plant litter, particulate organic matter, dissolved organic matter, and mineral-associated organic matter) of the soil, either directly or after metabolic transformation by soil biota. Points are lost through either respiration by soil biota or leaching. We invite readers to play this game and explore different natural ecosystems and land-use scenarios to better comprehend complex soil processes.

Information on natural resource exploitation is vital for conservation but scarce in developing nations, which encompass most of the world and often lack the capacity to produce it. A growing approach to generate information about resource use in the context of developing nations relies on surveys of resource users about their recollections (recall) of past harvests. However, the reliability of harvest recalls remains unclear. Here, we show that harvest recalls can be as accurate to data collected by standardized protocols, despite that recalls are variable and affected by the age of the recollecting person and the length of time elapsed since the event. Samples of harvest recalls permit relatively reliable reconstruction of harvests for up to 39 years in the past. Harvest recalls therefore have strong potential to inform data-poor resource systems and curb shifting baselines around the world at a fraction of the cost of conventional approaches.

Large-scale tree planting on global rangelands is promoted as a natural climate solution (NCS), but there is little scientific evidence to support this narrative. The presumed benefits of rangeland afforestation originate from five major misconceptions: (1) conflation between reforestation and afforestation, (2) overestimation of carbon (C) sequestration potential, (3) insufficient recognition of rangeland ecosystem services, (4) potential for adverse ecological outcomes, and (5) neocolonial tendencies of afforestation programs. Rangeland afforestation possesses minimal potential for additional C storage, but it has high potential to reduce vital rangeland ecosystem services that benefit rangeland residents and non-residents alike. Conservation of existing C—most of which is stored belowground, where it is less vulnerable to loss—may prove to be the most appropriate NCS for extensively managed rangelands. Stewardship strategies promoting rangeland multifunctionality will not only contribute to climate-change mitigation but also support biodiversity conservation and sustainable production of high-protein foods for marginalized populations.

Female crab spiders (Thomisus spp) are able to camouflage themselves as flowers not only to successfully avoid being preyed upon by birds but also to ambush flower-visiting insect prey (Nature 2002; doi.org/10.1038/415133a). This mimicry manipulates flower signals and may vary from species to species. However, do male crab spiders, which are usually much smaller in size and darker in coloration than females, also camouflage themselves in this way?

In a tropical rainforest in Xishuangbanna (Yunnan, China), we observed one male and one female crab spider (Thomisus guangxicus; Thomisidae) in an apparent partnership, to jointly mimic a single Hoya pandurata (Asclepiadaceae) flower. In this image, where the male crab spider lies on the back of the conspecific female, the male appears to mimic a flower's pistils and stamens while the female appears to mimic that same flower's fused corolla. The flower's complex color is matched as a whole only when individual spiders of both sexes are present. This could be an example of “cooperation” that expands the niche of both females and males in mimicry systems, and cooperating individuals may have improved survivorship and predation efficiency. It would also be interesting to investigate the co-evolution between male and female crab spiders.

The world's largest extant fish, the whale shark (Rhincodon typus), is a docile giant that occurs in tropical and subtropical regions globally. It prefers to feed on plankton, which it filters through its wide mouth. Adult whale sharks have been reported to occur in large numbers during warm summers off the Azores, an isolated archipelago on the mid-North Atlantic ridge (PLoS ONE 2014; doi.org/10.1371/journal.pone.0102060). As this oceanic region is oligotrophic, the whale shark's favorite food is not abundant. Instead, we found that they prey on snipefish (Macroramphosus sp) that have been corralled into “bait balls” at the surface by large schools of bluefin (Thunnus thynnus) and tropical tunas, including bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis), and yellowfin (Thunnus albacares). A feeding frenzy often ensues. With the baitfish corralled, the whale sharks then rely on powerful suction to fill their massive mouths with prey. This shark–tuna feeding association has rarely been observed elsewhere, yet in these islands it is the norm when both whale sharks and tunas are present. We have tagged whale sharks with high-resolution biologgers (with accelerometers, cameras, and gauges to measure location, pressure, and temperature) to help elucidate the ecological importance of this unique associative behavior.

As their name implies, ground birds typically spend much of their time foraging on the ground. Regardless of their capacity to fly, ground birds all use their legs more than their wings; for those that can fly, they usually do so to escape predators or reach areas that are inaccessible by walking. This is the case of the red-legged seriema (Cariama cristata; Cariamidae), avian symbol of the Cerrado (Brazilian savanna). Capable of reaching 90 cm in length and weighing up to 1.5 kg, seriemas search for and prey on insects and small vertebrates on the ground (Rev Bras Ornitol 2016; doi.org/10.1007/BF03544333). If pursued, seriemas can run at speeds up to 70 km per hour before taking flight. But how does this imposing bird deal with muscle fatigue in its legs?

In the Cerrado of Minas Gerais, Brazil, this adult specimen—after a long walk, in search of food—climbed onto a termite mound and, after raising and placing its right foot onto its left leg, remained static for about 15 minutes while observing the landscape before returning to hunting. To the best of my knowledge, the behavior captured in this photograph has not been previously reported in seriemas.

Does this posture allow a bird to distribute its weight without requiring muscle work by the supporting leg? Does the bird take turns standing on each of its legs? Do seriemas expend less energy when standing on one leg than when standing on two legs, similar to flamingos (Phoenicopteridae) (Biol Lett 2017; doi.org/10.1098/rsbl.2016.0948)? Does this behavior help regulate body temperature? Standing on one foot may be an important strategy for energy regulation in these birds.

Three major taxa comprise the bulk of the diet of the common octopus Octopus vulgaris (class Cephalopoda). Besides mollusks and crustaceans, some small fishes (infraclass Teleostei) are also typically found in octopus stomachs (Thalassas 2018; doi.org/10.1007/s41208-018-0084-z). In June 2020, we witnessed a predation event of O vulgaris on the common guitarfish or shovelnose ray Rhinobatos rhinobatos (class Chondrichthyes, subclass Elasmobranchii) off the coast of Cabo de Palos (southeastern Spain, western Mediterranean). To the best of our knowledge, this observation is the first documented record of predation between these two species.

We observed the predation event while hovering at a depth of 15 m in the ecotone between a seagrass (Posidonia oceanica) meadow and the sandy bottom. The very large octopus had completely immobilized the guitarfish, which was on its back on the seafloor with no chance of escape. How did these two animals initially encounter each other? Did the octopus actively prey on the fish? Given the peculiarity of the event, we hypothesize that the guitarfish was presumably injured or weak, especially considering the opportunistic feeding behavior of the octopus. This recorded event is especially relevant from a conservation viewpoint, given that R rhinobatos is considered extirpated from Spanish Mediterranean waters and is globally cataloged as Critically Endangered on the IUCN Red List of Threatened Species (see also Newell 2017; https://repository.library.noaa.gov/view/noaa/16215).

Protecting wildlife movement corridors is critical for species conservation. Urban planning often aims to create corridors for animal movement through conservation initiatives. However, research on connectivity for urban wildlife is limited. Here, we assessed connectivity for coyotes (Canis latrans) dynamically across temporal scales and demographic traits, parametrized using the habitat selection of 27 global positioning system (GPS)-collared coyotes in the city of Toronto, Canada. The habitat selection models accounted for human population density, impervious area, vegetation density, and distance to different linear features. Results indicated that (1) vegetation-dense areas were key for connectivity in urban areas; (2) riverbanks, railways, and areas below power lines were predicted as movement corridors; and (3) commercial and industrial clusters strongly disrupted connectivity. Spatiotemporal differences in connectivity were associated with time of day and coyote social status but not with climate and biological seasonality or coyote age and sex. Residential roads were pivotal in the temporal dynamism of connectivity. The maintenance and enhancement of plant structural complexity along key infrastructure (for example, highways, waterways, and parking lots) should be considered when managing connectivity corridors in cities.

Predicting species extinction is challenging in the context of climate change. The International Union for Conservation of Nature (IUCN) Red List of Threatened Species assesses species extinction risk by accounting for population size and global range of taxa, but this approach neglects the importance of genetic variability. Here, we propose a life strategy index (LSI) for predicting the extinction risks of species under climate change. The LSI is composed of three fundamental and independent components: namely, evolutionary potential, ecological potential, and colonization potential. The LSI constitutes a so-called “cask” theory of species extinction, which predicts that extinction likelihood is determined by the relative deficiency of any of the three components. The indicative variables used to construct the proposed LSI make the index applicable to assessments of (and predictions for) the extinction risk of different taxa in the face of climate change, which can inform management and conservation of imperiled species in a more scientific and precise manner.