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Biomass

Measuring Biomass

Species diversity and count is an important metric, but only one metric, of ecosystem health. By raw biomass, Earth is a planet of plants. Among large animals, humans and livestock dominate. There is additionally a large, not yet well understood, bacterial ecosystem deep within the Earth's crust 1.

The image: "earth_biomass.svg" cannot be found!

Source: Bar-On et al. 2.

The population of life on Earth has been estimated as follows.

The image: "earth_pop.svg" cannot be found!

Estimated populations of various taxa of living creatures. Estimates of trees are taken from 3 and the others from 2. See also a PDF rendition of this data.

Since the Paleolithic, human activity has led to a dramatic shift of Earth's biomass composition.

The image: "biomass_change.svg" cannot be found!

Source: Bar-On et al. 2.

Human modification of the biosphere predates industrialization and agriculture. Hunting, and perhaps competition with other animals for food and habitat modification, are the major factors behind the Quaternary extinction event, or the loss of a large fraction of the world's large animal species, starting 50,000 years ago 4.

Insect Populations

Worldwide, populations of insects have been sharply declining, though the exact amount is unclear.

RegionMetricTime FrameChange
Southern Scotland 5Number of Insects1970-2002- Two Thirds
Southern England 5Number of Insects1970-2002No Change
Worldwide 6Number of Insects1970-2008-30%
Worldwide 6Number of Vertebrates Besides Insects1970-2008-75%
Germany 7Number of Flying Insects1989-2016-76%
Germany 7Number of Flying Insects, Midsummer1989-2016-82%
Puerto Rico 8,9Ground-foraging arthropods--2.7% annually
Puerto Rico 8,9Canopy-welling arthropods--2.2% annually
Netherlands 10Number of Butterflies1890-2017-84%
Sweden 11Insects at Risk-60%
Worldwide 9 (conclusion disputed 12)Insects at Risk-40%
Worldwide 13Insects at Risk-10%
Worldwide 14 (Methodology Disputed 15,16)Number of Terrestrial Insects--9% per decade
Worldwide 14 (Methodology Disputed 15,16)Number of Freshwater Insects-+11% per decade
United States 17 (Methodology Disputed 18,19)Number and Diversity of Insects4-36 years, depending on monitoring siteNo change

These observations can be confirmed by the "windshield effect": the observation that there are many fewer insects splattered on one's windshield after a rural drive today than a few decades ago 5.

The precise causes of the decline are not clear. Land use change for agriculture 9 and the use of pesticides 20 are suspected to be the leading culprits.

Colony Collapse Disorder

Colony collapse disorder (CCD) is the disappearance of most worker bees in a colony. The cause of CCD remains unclear, and it is likely that CCD results from a combination of several stresses on colonies 21. A class of pesticides known as neonicotinoids have been found to cause neurological damage to honeybees and is a suspected contributing factor to CCD 22, but the importance of neonicotinoids at environmentally relevant concentrations is uncertain 23.

The winter mortality rate for honeybee colonies for 2007-2014 is 29.6%, and it was 14% prior to the emergence of CCD 24. Nevertheless, this increased mortality has not led to a significant reduction in the number of colonies, as beekeepers have responded with increased breeding 24. The economic cost in increased fees for pollinator services for almond crops in the United States has been estimated at $120 million in 2013 24. For crops other than almonds, no impact economic impact has been identified 25.

Wildlife Mortality

Following are estimates of the human causes of deaths among birds in the United States.

The image: "bird_deaths.svg" cannot be found!

Numbers are highly approximate; for example, Loss et al. 26 put the numbers of deaths by cats significantly higher. Source: 27.

References

  1. McMahon, S., Parnell, J. "The Deep History of Earth’s Biomass". Journal of the Geological Society 175(5). September 2018. ↩

  2. Bar-On, Y., Phillips, R., Milo, R. "The biomass distribution on Earth". Proceedings of the National Academy of Sciences of the United States of America 115(25), pp. 6506-6511. June 2018. ↩ ↩2 ↩3

  3. Crowther, T. et al. "Mapping tree density at a global scale". Nature 525, pp. 201-205. December 2015. ↩

  4. Koch, P., Barnosky, A. "Late Quaternary Extinctions: State of the Debate". Annual Reviews of Ecology, Evolution, and Systematics 37, pp. 215-250. 2006. ↩

  5. Vogel, G. "Where have all the insects gone?". Science, pp. 576-579. May 2017. ↩ ↩2 ↩3

  6. Dirzo, R., Young, H. S., Galetti, M., Ceballos, G., Isaac, N. J. B., Collen, B. "Defaunation in the Anthropocene". Science 345(6195), pp. 401-406. July 2014. ↩ ↩2

  7. Hallmann, C. A., Sorg, M., Jongejans, E., Siepel, H., Schwan, H., Stenmans, W., Müller, A., Sumser, H., Hörren, T., Goulson, D., de Kroon, H. "More than 75 percent decline over 27 years in total flying insect biomass in protected areas". PLoS One 12(10): e0185809. October 2017. ↩ ↩2

  8. Lister, B. C., Garcia, A. "Climate-driven declines in arthropod abundance restructure a rainforest food web". Proceedings of the National Academy of Sciences of the United States of America. 115(44), pp. E10397-E10406. October 2018. ↩ ↩2

  9. Sánchez-Bayo, F., Wyckhuys, K. A. G. "Worldwide decline of the entomofauna: A review of its drivers". Biological Conservation 232, pp. 8-27. April 2019. ↩ ↩2 ↩3 ↩4

  10. van Strien, A. J., van Swaay, C. A. M., van Strien-van Liempt, W. T. F. H., Poot, M. J. M., Wallis De Vries, M. F. "Over a century of data reveal more than 80% decline in butterflies in the Netherlands". Biological Conservation 234, pp. 116-122. June 2019. ↩

  11. Altermatt, F., Pauli, D. "Disparition des insectes en Suisse et conséquences éventuelles pour la société et l’économie". Académies suisses des sciences (in Swedish). 2019. ↩

  12. Pensoft Publishers. "'Insectageddon' is 'alarmist by bad design': Scientists point out the study's major flaws". ScienceDaily. March 2019. ↩

  13. Fan, H., Yang, Z., Wang, H., Xu, X. "Estimating willingness to pay for environment conservation: a contingent valuation study of Kanas Nature Reserve, Xinjiang, China". Environmental Monitoring and Assessment 180(1-4), pp. 451-459. September 2011. ↩

  14. van Klink, R., Bowler, D. E., Gongalsky, K. B., Swengel, A. B., Gentile, A., Chase, J. M. "Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances". Science 368(6489), pp. 417-420. April 2020. ↩ ↩2

  15. Desquilbet M., Gaume L., Grippa M., Cereghino R., Humbert J. F., Bonmatin J. M., Cornillon P. A., Maes D., Van Dyck H., Goulson D. "Comment on “Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances”". Science. 370(6523):eabd8947. December 2020. ↩ ↩2

  16. Jähnig S. C., Baranov V., Altermatt F., Cranston P., Friedrichs‐Manthey M., Geist J., He F., Heino J., Hering D., Hölker F., Jourdan J. "Revisiting global trends in freshwater insect biodiversity". Wiley Interdisciplinary Reviews: Water 8(2):e1506. March 2021. ↩ ↩2

  17. Crossley M. S., Meier A. R., Baldwin E. M., Berry L. L., Crenshaw L. C., Hartman G. L., Lagos-Kutz D., Nichols D. H., Patel K., Varriano S., Snyder W. E. "No net insect abundance and diversity declines across US Long Term". Ecological Research sites. Nature Ecology & Evolution. 4(10) pp. 1368-1376. October 2020. ↩

  18. Welti E. A., Joern A., Ellison A. M., Lightfoot D. C., Record S., Rodenhouse N., Stanley E. H., Kaspari M. "Studies of insect temporal trends must account for the complex sampling histories inherent to many long-term monitoring efforts". Nature Ecology & Evolution 5(5), pp. 589-591. May 2021. ↩

  19. Desquilbet M., Cornillon P. A., Gaume L., Bonmatin J. M. "Adequate statistical modelling and data selection are essential when analysing abundance and diversity trends". Nature Ecology & Evolution. 5(5), pp. 592-459. May 2021. ↩

  20. Croft, D. ("The effects of insecticides on butterflies: A review")[https://radar.brookes.ac.uk/radar/items/fddc88d3-25f2-4274-9321-2f9b3b72047a/1/]. Environmental Pollution 242, pp. 507-518. November 2018. ↩

  21. Williams G. R., Tarpy D. R., Chauzat M. P., Cox-Foster D. L., Delaplane K. S., Neumann P., Pettis J. S., Rogers R. E., Shutler D. "Colony collapse disorder in context". Bioessays 32(10), pp. 845-846. October 2010. ↩

  22. Lu, C., Hung, Y., Cheng, Q. "A Review of Sub-lethal Neonicotinoid Insecticides Exposure and Effects on Pollinators". Current Pollution Reports 6, pp. 137-151. March 2020. ↩

  23. Carreck, N. L., Ratniecks, F. L. W. "The dose makes the poison: have “field realistic” rates of exposure of bees to neonicotinoid insecticides been overestimated in laboratory studies?". Journal of Apicultural Research 53(5), pp. 607-614. 2014. ↩

  24. Rucker, R. R., Thurman, W. N., Burgett, M. "Colony Collapse and the Economic Consequences of Bee Disease: Adaptation to Environmental Change". January 2016. ↩ ↩2 ↩3

  25. Ferrier, P. M., Rucker, R. R., Thurman, W. N., Burgett, M. "Economic Effects and Responses to Changes in Honey Bee Health". United States Department of Agriculture, Education Research Service. Economic Research Report Number 246. March 2018. ↩

  26. Loss, S., Will, T., Marra, P. "The impact of free-ranging domestic cats on wildlife of the United States". Nature Communications 4, Article Number 1396. January 2013. ↩

  27. Erickson, W., Johnson, G., Young, D. "A Summary and Comparison of Bird Mortality from Anthropogenic Causes with an Emphasis on Collisions". In: Ralph, C. John; Rich, Terrell D., editors 2005. Bird Conservation Implementation and Integration in the Americas: Proceedings of the Third International Partners in Flight Conference. 2002 March 20-24; Asilomar, California, Volume 2 Gen. Tech. Rep. PSW-GTR-191. Albany, CA: U.S. Dept. of Agriculture, Forest Service, Pacific Southwest Research Station: p. 1029-1042. 2005. ↩