I am wondering if a latitudinal gradient holds up for lichens as it does for just about all other forms of life. This is a difficult question. Interestingly, a google search mentions global hotspots in Alaska (1300) and New Zealand (over 2000).
On a local level, diversity is highest in areas well away from air pollution and in old forests.
I’d guess glaciers had less impact on lichens compared to other groups, plus most species living on rocks (probably), means the more rockier places would have more species. As they’re growing slower than plants, they thrive in places where plants feel not as good, so again rocks. So I think iNat map kinda shows it correctly for those places with enough observers.
I just found the answer. I did a search on “lichen diversity in the tropics” and came by this article: https://www.fungimag.com/summer-2014-articles/LR1%20V7I2%2028-31%20Jungle.pdf In the article, in Costa Rica, it is possible to find about 600 species per hectare.
Living in a temperate rainforest far from pollution, my own experience says that lichens are just about the predominant life form; they’re covering just about everything, including man-made things that have been outside a while. Their total mass and number of species must exceed those in the mountains, where they cover the rocks but there’s not as many trees to cover.
Yeah, that’s an interesting point, but also good old forests are nice hotspots for lichens, here in my area I’ve seen more lichens on tree trunks.
Part of the issue is that tropical lichens haven’t been studied nearly as much as temperate ones, especially ones in wealthy, easy to access developed nations with good science programs and the resources and training needed to accurately identify lichens and sus out new species.
Now I need to see if I still have a certain picture from years ago…
I absolutely agree. Here in Germany more than 1700 species of lichens have been recorded and it is definitely not a species hotspot. Sadly several hundred species are already extinct and i have only observed 96 of the 1700 species so far (probably more but was not able to identify them).
I think there are a lot of tropical species that still have to be discovered, but the biggest lichen diversity might be in colder climates. I think there is a fierce competition with mosses, bromeliads, orchids etc. in the tropics. Lichens usually need enough light, a lot of time and and relatively constant growth conditions.
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