Many fungi have prefered habitats and/or substrates, or are mycorrhizal with associated trees. An understanding of this can not only help in finding them but also aid their identification. The Auckland region has a number of different forest types as well as man made habitats. Our forests are not pure stands of any one tree, but generally a mixture of several types.
Lowland Broadleaf / Podocarp
Podocarps are our big forest trees, found at low altitude throughout the country except in the drier eastern parts of the South Island. Within the Auckland region, there are no undisturbed stands of these to be found, having most long since been cut over. Never the less, in the Waitakere, as elsewhere, these are regenerating. Such forests, with their diversity, offer some of the best opportunities for fungi hunting.
The Kauri tree is one of our most impressive trees for its long life span and large size. It's unfortunate that the vast kauri forests once found in the Auckland region are no more. With only isolated pockets of mature trees to be found, those were usually too difficult to extract and mill. I have had mixed results with finding fungi under these. Generally there are few to be found, but on occasions I have come across some nice displays of waxgills.
The Tea tree bush is one of the most common forest types found in the Auckland region due to the milling and clearing of Auckland's Kauri and Podocarp forests earlier this century. These are pioneer species, and one of the first trees to become established in the process of regeneration. due in part to their mycorrhizal fungi and ability to set seed when only a few years old. Once established, they provide shelter for many other tree species.
A large number of mycorrhizal fungi are found under Tea trees and some of these are also found under Nothofagus (beech), such as Amanita australia.
Nothofagus or beech forests are not common in the Auckland Region because we are at the northern limit of their range, with only Hard Beech ( Nothofagus truncata ) found this far north, if you know where to look, particularly in the Hunua Rangers, beech trees can be found. These tend to be much dryer and lack the large mossy ground cover that can be found in the southern beech forest.
Beech trees, being mycorrhizal, tend to be dominated by Cortinarius and, to a lesser extent, Amanita, Russula, and Laccaria species, but not restricted to just these. Many of these fungi only accrue under beech, so it's well worth seeking these out.
These tend to be places where many exotic mycorrhizal fungi can be found, usually accidentally introduced with imported trees. Unfortunately, many of these are also poisonous, including the Death Cap (Amanita phalloides), which is associated with oak trees. This fungus is one of the worst to eat, with immature fruiting bodies being mistaken for field mushrooms, with the result that poisonings (kidney/liver damage) and sometimes death are not uncommon.
Oddly, one species, Birch bolete (Leccinum scabrum) which is associated with silver birch, is a tasty fungus and easily identified, even though few know of it and would not consider eating a bolete.
Open grasslands or farmland is home to some of our best fungi for eating Meadow mushrooms ( Agaricus campestris ) and Horse mushrooms ( Agaricus arvensis ) being top of the list with lesser known Shaggy ink cap (Coprinus comatus) not far behind. Still, some care is needed to make sure you do not pick any of the white, similar species like Smooth parasol (Leucoagaricus leucothites ).
Unfortunately, many of these species are now on the decline due to modern farming practices. The application of fertiliser and fungi don't mix. Many are now restricted to grass verges, urban parks, and unimproved farmland.
Wood chip mulch has in recent years become a very popular landscaping material seen in many urban parks, along road verges, and in private gardens. There are many fungi that just love this environment, and some impressive mass fruiting can be seen during autumn and sometimes right through winter.
Many of the fungi are cosmopolitan species found throughout the world, while others are native to New Zealand, having fled the bush for this much more agreeable habitat.
Coprophilous fungi are a small and diverse group of saprobic fungi which help to break down animal dung. Although most are microscopic in size, a few have large fruiting bodies that are found during wet conditions. The dung of herbivores consists mostly of undigested plant remains due to the inefficiency of the animal's digestive system. These plant remains are only partly broken down, making them an excellent source of nutrients for the growth of fungi.
The dung of carnivores and omnivores contains a lot more sugar and is usually broken down by bacteria. During wet conditions, fungi can also be found on these too.
There is another small group of fungi which attack and kill insects; the fungus lives within the insect for a time before killing it. At which point it produces fruiting bodies to spread their spores.
In Auckland, two species are very common, the Vegetable Cicada (Isaria sinclairii) which attacks the cicada grub while underground and sends up a stalked fruiting body to the surface to release its spores; and The other is the sugar icing fungus (Cordyceps bassiana) which attacks a wide range of hosts, most commonly mature cicadas but also beetles, wasps, and stick insects.