Insects are by far the most varied and abundant animals, outweighing humanity by 17 times, and are essential to the ecosystems humanity depends upon. They pollinate plants, are food for other creatures and recycle nature’s waste.Damian Carrington, Environment editor, The Guardian, 24 April 2020
Nearly two years ago Alloporus first noted some worrying research on the decline of insects in Europe. with the key finding
More than 75% decline over 27 years in total flying insect biomass in protected areasHallman et al (2017)
Alloporus’ comment was this
When an observation so dramatic and material to so many key ecological processes becomes known we dismiss it at our peril. If we ignore these numbers just because we like the idea of fewer midges at summer evening picnics without looking deeper to find out what is going on, we increase the risk to our already precarious food security.
At around the same time this post and research came out, two US researchers returned to a forested conservation reserve in Puerto Rico after 35 years and this is what they said…
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.
They published their results in a peer-reviewed journal of the US National Academy of Sciences
Lister, B. C., & Garcia, A. (2018). Climate-driven declines in arthropod abundance restructure a rainforest food web. Proceedings of the National Academy of Sciences, 115(44), E10397-E10406.
The declines the authors put down to climate. It was too hot too often for the ground-dwelling invertebrates creating an upwards cascade through the food web.
In Europe insecticide use and habitat change, in a rainforest, climate change. Either way a serious problem.
Just to make sure this was not just an isolated result, Roel van Klink of the German Centre for Integrative Biodiversity Research, together with colleagues from around Germany and Russia completed a meta-analysis and
‘compiled data from 166 long-term surveys across 1,676 globally distributed sites and confirmed declines in terrestrial insects, albeit at lower rates than some other studies have reported and concluded that ‘Patterns of variation suggest that local-scale drivers are likely responsible for many changes in population trends, providing hope for directed conservation actions.’
So it’s happening. Roughly 25% declines in insects across the board in a generation, with insects faring only slightly better in nature reserves than outside protected areas.
The conclusion, terrestrial insects are declining in numbers and variety and, as is typical for nature, this loss is patchy, occurs at differing rates and from multiple causes.
Klink and his colleagues took hope from this result. You can see why. If climate change was the cause everywhere, then there is a serious global catastrophe in the offing where the rates of decomposition and nutrient transfer are altered across a wide range of biomes and habitats affecting many land uses, especially primary production.
This would not be about species loss in the way it is for the koala. A cute thing that we like to see in the zoo and maybe take a selfie with one held up by a zookeeper, the cuddly critter that might become extinct. This is about the loss of function, loss of ecosystem services that we cannot do without or easily replace.
Instead, Klink and his colleagues found multiple, often local causes. This they interpret as a solvable problem. Conservation and restoration efforts could help local populations recover.
As regular readers will know, Alloporus has to work hard to be this optimistic.
Until the economy through the supply chains feels the hit of the loss of services little will be done. The efforts of the few with the koala saving gene will be epic, they will try their best, but it will not be enough.
If lockdown with its boredom, ingenuity and the appearance of clean air all around the place tells us anything, it should be that we can survive on relatively little.
Only part of that little has to be food and water.
Imagine lockdown with the supermarket shelves empty of food. That would put toilet paper shortages into perspective for us.
It is trite to say it, and sad that it has to be said again and again, but it is true — nature matters to our very existence.
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