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Life Under An Urban Log - Gardiner’s Creek This Morning

Biodiversity is everywhere…rainforests, the ocean’s abyssal plains, New York sidewalks, arctic tundra. Like all these places, urban parks are full of biodiversity…most of it inconspicuous and rarely seen.

So this-morning-tea-time I went for a walk - from my lab (in Melbourne, Australia) down to the nearby re-vegetated creek line - 325 steps. My brain was in slow mode and it needed speeding up. Under the first log I rolled there were piles of creatures and my brain switched back on when the first one I focused on, an isopod hunting spider (Dysdera crocata: Dysderidae), bit me…or tried to. Although they have large chelicerae, they are not a danger to humans like almost all of the tens of thousands of species of spiders inhabiting the planet. Dysdera is introduced to Australia and it is widely established in parks and gardens in the southeast of the country.

There were dozens of millipedes of three or four species, dominantly  Portuguese millipedes (Ommatoiulus moreleti) and several other introduced species (like the little bubbas above) including one native species thought to be introduced to Melbourne from central New South Wales. Even natives can be invaders.

But even in this urbanised habitat dominated by non-native species there are still indigenous species on the ground. Ground dwelling species are apparently much less resilient to invaders it seems, but that is an entirely different story. The larva of scarab beetles and their relatives are common under logs and in the soil where they feed on the roots of plants. Beetles feed on decaying wood and other detritus - the cossonine weevil (fourth image) is an example. Native ground beetles (Carabidae) predate on the invertebrates, presumably mainly introduced species. Even the occasional native landsnail (a member of the Charopidae in this case) can be found amongst the introduced slugs and snails.

Is the ongoing ecological development (‘gardening’) of these reconstructed habitats going to improve the lot of the native invertebrates that inhabit them?

I doubt it but its worth keeping an eye on the Many Little Things that live there!