Can weeds save a rainforest? Fragmentation, Restoration and Succession.
Although seldom talked about, habitat fragmentation is one of the fundamental issues of our age. Secondary regrowth - where vegetation regrows naturally and spontaneously following a history of habitat loss, without human intervention or management - can restore much needed biodiversity and connectivity to fragmented landscapes. However, such "passive restoration" may be degraded in the sense of having reduced species diversity, and a dominance of exotic weeds. Intuitively, such "weed forests" seem a poor outcome, but in this talk he presented some surprising results from the Camphor Laurel forests that dominate regrowth on former rainforest lands in northern New South Wales.
Although these forests are indeed dominated by the exotic weed camphor laurel today, they already harbour a surprising diversity of native species, and - what is more exciting - there is clear evidence that over time they are likely to transition into a vegetation that increasingly resembles native rainforest. Far from being an ecological disaster-area, in this instance the weed-dominated regrowth may in fact represent an important conservation asset in the landscape.
(This information comes from a talk given by Dr John Hall at a CDEA public meeting on 28 February 2019)