the astonishing decline in the insect population
I do think people are beginning to notice this at last. But it's a very data poor area - new species are being identified and described all the time. We can hardly make comparisons if we don't have historic data. Car number plates is a useful index, but only of insects that are relatively big, black, and inhabit places where roads go through, together with old people's memories of having to wash squished insects off car windscreens more or less frequently, compared with no longer finding that necessary. It's not a great baseline.
Hitherto bigger animals have hogged most zoological attention (and funding) and most invertebrates are damned difficult to spot - they've been perfecting their camouflage for hundreds of millions of years, because they're food for so many other species, including chickens - how many of us have commented on this thread that despite our best efforts, we can't see what exactly the chickens are eating when they forage? The recent finding of an enormous 41 cm long, 44g weight stick insect in Australia really displays the level of oversight and ignorance the entire invertebrate kingdom has suffered.
It's quite sobering. Since I have been trying to identify all the flora, fauna and funga in the garden, I have discovered that most of what I hitherto thought were bees are, in fact, other things mimicking bees, including a fly that's bigger than any bumble bee here, and all predatory wasps I've found were only in the 'I was here' form of what they leave behind.
This insect population decline is in part why the field looks so brown; we haven't cut the grass much anywhere. Not cutting will hopefully help with insect habitat
Yes. Don't clear it all away in autumn. It's essential overwinter habitat. Short grass is necessary for some species. Variety is the key to success, as usual.
eight to twelve inches of soil and then it's rocks
This can build up quite quickly with leaf litter left in situ. And it helps with moisture retention. Rain is held temporarily, better allowing it to seep into the ground, instead of flowing off as it does in areas left without leaf litter, often taking the topsoil with it. It's leaf litter that sustains the decomposers and detritivores that recycle the nutrients that went into the plant. 'Tidying up', an autumn gardening ritual I was brought up with, turns out to be really detrimental to the garden, stripping off nutrients and microlife essential to soil health, which then requires imported fertilizers of some sort to replace what was already there, before it was 'tidied' away. I have found you can get a good growing medium in just 2 years *just on tarmac* if you leave the autumn leaves where they fall. It has made me question the extraordinarily long timespans said to be required to 'make' soil. They must be counting from igneous rock simply exposed to the weather I think. Organic matter creates humus annually and once something has a foothold, it makes it easier for others to follow.
It's all incredibly complicated this environment we live in and we have not got a clue about what we are doing and the long term consequences of our doings.
Yes. Absolutely.