Climate-driven declines in arthropod abundance restructure a rainforest food web

By B. Lister, Andrés García. Proceedings of the National Academy of Sciences of the United States of America, 2018

622 citations recorded by the source corpus.

Significance Arthropods, invertebrates including insects that have external skeletons, are declining at an alarming rate. While the tropics harbor the majority of arthropod species, little is known about trends in their abundance. We compared arthropod biomass in Puerto Rico’s Luquillo rainforest with data taken during the 1970s and found that biomass had fallen 10 to 60 times. Our analyses revealed synchronous declines in the lizards, frogs, and birds that eat arthropods. Over the past 30 years, forest temperatures have risen 2.0 °C, and our study indicates that climate warming is the driving force behind the collapse of the forest’s food web. If supported by further research, the impact of climate change on tropical ecosystems may be much greater than currently anticipated. A number of studies indicate that tropical arthropods should be particularly vulnerable to climate warming. If these predictions are realized, climate warming may have a more profound impact on the functioning and diversity of tropical forests than currently anticipated. Although arthropods comprise over two-thirds of terrestrial species, information on their abundance and extinction rates in tropical habitats is severely limited. Here we analyze data on arthropod and insectivore abundances taken between 1976 and 2012 at two midelevation habitats in Puerto Rico’s Luquillo rainforest. During this time, mean maximum temperatures have risen by 2.0 °C. Using the same study area and methods employed by Lister in the 1970s, we discovered that the dry weight biomass of arthropods captured in sweep samples had declined 4 to 8 times, and 30 to 60 times in sticky traps. Analysis of long-term data on canopy arthropods and walking sticks taken as part of the Luquillo Long-Term Ecological Research program revealed sustained declines in abundance over two decades, as well as negative regressions of abundance on mean maximum temperatures. We also document parallel decreases in Luquillo’s insectivorous lizards, frogs, and birds. While El Niño/Southern Oscillation influences the abundance of forest arthropods, climate warming is the major driver of reductions in arthropod abundance, indirectly precipitating a bottom-up trophic cascade and consequent collapse of the forest food web.

Subfields: Ecological Modeling, Ecology, Evolution, Behavior and Systematics, Social Psychology

View Paper: https://www.semanticscholar.org/paper/f29ff7e7a9333947b0aaf530f499f518c503d9e1

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Citations in the corpus

Insect responses to global change offer signposts for biodiversity and conservation (2020, methodology): “Intermittent temporal “snapshots” of communities or populations have also been employed (Lister & García, 2018; Harris et al., 2019).”
Further evidence for a global decline of the entomofauna (2020, background): “…recent publication of several reports on the decline of insects and other arthropods in areas of Europe and Central America (Hallmann et al. 2017; Lister and Garcia 2018; Seibold et al. 2019; van Strien et al. 2019; Hallmann et al. 2020) as well as our review of patterns at the global level…”
Declining abundance of beetles, moths and caddisflies in the Netherlands (2019, background): “Comparison of the presented abundance trends with the German (−76% in biomass) and Puerto Rico (−98% in abundance) results (Hallmann et al., 2017; Lister & Garcia, 2018) remains difficult because insect traps vary widely in which groups of insects are sampled (Russo et al., 2011).”
Keeping invertebrate research ethical in a landscape of shifting public opinion (2019, background): “However, there also needs to be space for well justified studies which use non-selective trapping throughout the year as these can be the only way to collect critically important data with important conservation outcomes (Hallmann et al., 2017; Lister & Garcia, 2018).”
Worldwide decline of the entomofauna: A review of its drivers (2019, background): “There is also clear evidence that climate change is reducing arthropod biomass in the rainforests of Caribbean islands (Lister and Garcia, 2018).”
Interpreting insect declines: seven challenges and a way forward (2020, background): “The quality of some of these papers has been relatively weak, either due to misinterpretation of data (Lister & Garcia, 2018) or due to overzealous claims (Sánchez-Bayo & Wyckhuys, 2019).”
The human imperative of stabilizing global climate change at 1.5°C (2019, background): “There are indications that climate change has already contributed to observed declines in insects and arthropods in some regions (21, 22).”
Insect Declines in the Anthropocene. (2020, methodology): “One unfortunate conclusion of this review is that many declines are occurring inside preserves (28, 68, 87, 109, 148, 159).”
Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction (2020, neutral): “More recently, climate disruption is becoming a major cause of species endangerment (10, 11, 14 – 17).”
Geographical, temporal and taxonomic biases in insect GBIF data on biodiversity and extinction (2021, background): “One consequence of this asymmetry is that the dataset of vertebrates is more robust (with more georeferenced records and abundance data) than that of invertebrates (Lister & Garcia, 2018).”