Is there evidence of the idea that biodiversity has been declining for some time?

Yes, there is evidence for that.However, I must say that the group that is thought to be the fastest extinction, namely the insects, is also a group of which few large-scale data are available.

For example, a literature study has been developed that has looked at all the studies that have been carried out over the past few years, and concluded that 40% of all insects worldwide decrease by 2.5% each year.[1 If this trend continues, it would be done within a hundred years with the insects.All bad and well, but can you say that it is a global trend, if there are only 3 out of China compared to more than a hundred studies from the US and Europe? If entire continents, namely Africa and South America, are missing from your data? Well, that’s hard. But if we look closer to home, it is already more reliable, and we can see clear evidence.

When looking at insect counts, there are two ways most popular.The first is the volume counting, in which case you set up a tent and look at how many insects fly in (thus mainly about flying insects), i.e. put a container in the field and look at how many (species) of insects run in it at any given time. The first method was used in the now famous German study, which looked at 63 natural areas over a period of 27 years, and the findings were that the volume of insects decreased by 76%. [2 that is a huge decline.Moreover, there was no consideration of the number of species but of the biomass, but you can imagine that if the number of insects has decreased so drastically, the number of species also decreases.

I can imagine that you are not satisfied with that, and that is your good right.The second method to look at biodiversity is the types of census. In order to be more definitive about the types of reductions, it is useful to look at the measurements of the various red lists in the Netherlands. For example, if we look at the wild bees, the Red List of 2018 suggests that 55% of the 359 species of Dutch bees have been threatened or disappeared since the last RL from 2003. [3 However, the number of species that disappears is roughly balanced with the number of southern species that can settle down here by climate change.Since 1990, the number of species seems stable in the Netherlands, but the homogeneity of species in Europe is increasing.

Other studies found an equal decline in species of flora and species pollinators in the Netherlands and the UK, [4 Although the more specialised insects such as bees and butterflies were mainly affected, gliding flies seemed to do better.Also volunteer-driven counts such as the National Butterfly Count show a decline in species, “of the 47 species of which we can calculate trends, 23 go backwards, 11 ahead and 13 remain stable since 1992. 芒 鈧?a href=”#YpGur”>[5 This is a valuable census, because it assumes fixed routes which are counted, which are unchanged since 1992.This was a critical point on other studies, that measuring tents and bins were not always in the same places.

However, there are studies that show that the Dutch insect species are declining.The studies that can be most obvious about types of decline are those from the nature reserves, because most of the data has been collected here. But the Netherlands also knew a great biodiversity in its pastures, and although we have fewer dates, we can see, for example, the huge decline in meadow birds that these areas have become less species rich. Since the years 芒 鈧?虄 90 There is a decrease of 47% to see, some species like the Skylark have even decreased by 60%. [6 that makes their populations extremely fragile, we already saw that the Klapekster and Ortolan from the Netherlands disappeared.

The most interesting report on the Dutch biodiversity that I could find comes from 2014, a balance sheet for the living environment of the same Plan agency mentioned:

In the Netherlands, biodiversity decreased from approximately 40 percent in 1900 to around 15 percent in 2010.

Biodiversity is expressed here as MSA: Mean Species Abundance. An MSA of 15 percent means that the populations of indigenous plant and animal species have an average size of 15 percent of the natural situation. [7

It states that biodiversity in the Netherlands is lagging harder than in the rest of Europe, and more species are disappearing than that.The reason for this is the increasing homogeneity of the living environment.

Well, and that is where the meadow birds and insects are struggling.Thanks to the intensiation of agriculture, fields are overfertilised and overgrazed, which means that the plants and animals that lived in this habitat will no longer be able to stand. Also the emergence of 芒 鈧?虄megastallen芒 鈧劉 contributes to this. Monoculture crops such as corn and sugar beet are fortunately less than in countries like the USA, simply because the Netherlands is too small for this, but still disappear wild flowers, and the insects that depend on them. Thanks to changing agriculture, traditional aspects of Dutch agriculture, such as flowering cornfields (and species such as cornflower, Bolderic, and Cornwolf), the wood walls, the sand hills (and thus birds as partridges) disappear…

Well, but there are also farmers and organizations that try to bring them back, so there is a large-scale Dutch-Belgian project started last year to bring back The partridge.

You’ll probably think, the cornflower disappeared?De Bolderik? Are they in just about every flower seed mixture you can get? Yes, that’s right, but within species biodiversity has also decreased. As the natural populations disappear, only a few 芒 鈧?虄gene Pools芒 鈧劉 about where seed can be extracted from. Many klaproos seeds, for example, do not come from the Netherlands, but from large farms elsewhere in Europe. This means that regional variants disappear and the overall species become more homogeneous and thus more vulnerable to disease. This can be a kind of completely deleted. I am not exaggerating, that is also what happened to the Dutch elm. This applies double to rarer plants such as a thousand guilder and the Rhine Centaurie.

Um, which I want to go to, is that there is too little good data at the moment to be able to say: biodiversity is so and so hard to reverse per that and that species.Studies that make large-scale proclamations can be taken with a grain of salt. However, it can be argued that trends are visible at the local level, and they show a decrease in species and numbers. This is due to a changing climate and a less diverse landscape. There are also signs that exots have an influence on indigenous species (such as the New Zealand land platworm that aast on European earthworms, and is already feared in a number of countries), but for the moment Exots can only Weaken, do not eradicate.

I hope I have answered your question a little.

Footnotes

[1 BBC Radio 4-More or Less: Behind the Stats, Insectageddon

[2 Three-quarters of total insect population disappeared in protected natural areas

[3 wild Bees threatened

[4 Parallel Declines in pollinators and Insect-pollinated Plants in Britain and the Netherlands

[5 The Butterfly Foundation | Measuring net butterflies still show deterioration

[6 https://www.natuurmonumenten.nl/. ..

[7 biodiversity and causes of loss in Europe

Every time there is a kind of dying out, biodiversity decreases; And we are experiencing a global surge in extinction as it has not occurred in the last 65 million years.In addition, the amount of insects in western Europe has declined sharply over the last decades, even if a large number of species can still be found somewhere; But there are just too many fewer individuals. When I was small 50 years ago, your car window was after a long drive on the holiday to France full of crushed insects; Nowadays you don’t see that at all.

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