In the April Green Pages, I asked the reader to consider what the Walsingham nature reserves look like now, how they looked like a few decades ago and what they looked like before man arrived in Bermuda.This month let’s direct our attention to the hillsides in Warwick, which are covered in a forest made up primarily of allspice trees. What grew there before the allspice?In pre-colonial Bermuda (before man) these hillsides would have looked very different then they do now. They would have been cloaked with a cedar monoculture (dominant) — like much of Bermuda — with, perhaps, a few palmettos, woodgrass and Bermuda sedge would have grown, filling the niche at ground level under the canopy of the cedar forest.How did we get from the cedar forest to the allspice forest that grows there today?It’s not known when allspice was introduced to Bermuda but it was mentioned in two books on Bermuda’s plants in the 1880s and was described by botanist NL Britton in 1918 as growing on hillsides and “very abundant in Warwick.”Warwick was the centre for the spread of allspice. Allspice was coming in before the cedars died out in the early 1950s but, when they did die, the allspice spread and became a monoculture on the Warwick hillsides. Today allspice is found in every parish and is considered invasive.Invasive plants are plants, introduced to Bermuda by man, that not only spread by themselves but spread aggressively into natural or semi-natural areas, displacing native and endemic plants and forming monopolistic thickets and woodlands and threatening our biodiversity.Over the decades, the Warwick hillsides remained an allspice forest because allspice is a monopolistic invasive. Nothing, other than the Chinese fan palm (another invasive) and allspice’s own seedlings, can grow under the dense under-canopy of allspice; Chinese fan palm is invading the allspice forest, but our endemic Bermuda palmetto can’t.Allspice is wind-resistant and, because of this, it is very seldom that an opening is created in the forest canopy, except in hurricanes.However, there have been “events” that have created openings in the allspice forest (Hurricane Emily, in 1987, stripped foliage off the allspice) that have allowed Brazilian pepper and fiddlewood to make inroads into the allspice forest. The sickle-thorn asparagus fern, perhaps taking advantage of these openings, is also starting to invade the allspice forest. The hoop vine is perhaps the next plant to be on the lookout for over the next decade or so.Consider, on the other hand, the Paget hillsides. They are primarily covered in Surinam cherry and fiddlewood. Why, you may be wondering, are these hillsides in adjoining parishes covered with forests made up of different plants? This question was posed to David Wingate several decades ago, who, in trying to answer the question, realised that although the climate and habitat are fairly similar throughout much of the Island (the coastal habitat is one exception) it was luck of the draw where plants got started first. The first invasive species of plant to start growing in an area became dominant and by its presence would suppress later invasives. Surinam cherry reached Paget before allspice and, as a result, cherry is dominant.Now, go for a walk through these two areas. Go back again in a decade (and then another decade) to see how they have — or haven’t — changed.