canary islands I la gomera I the ecotone

Aerial photo, showing the abrupt transition from green to brown

Aerial photo, showing the abrupt transition from green to brown

Despite its much lower elevation (the highest point, Alto de Garajonay, rises to only 1487m), La Gomera displays a much more dramatic wet-dry ecological transition - between cloud forest and near-desert - than does Tenerife.   One reason is that La Gomera's laurisilva is better-preserved and more contiguous.  Another is that because of the island's lower topography, there is no intervening pine forest along the central ridge dividing the north and south, as there is along the ridgeline extending eastward from Tenerife's Caldera de las Canadas and surrounding the caldera itself.  Finally, whereas the two ecosystems do occur directly adjacent to one another along the narrow Peninsula de Anaga  at Tenerife's eastern end,  the topography is so steep that the transition from forested ridge to desert slopes appears as though it could result as much from differences in water retention as precipitation.  In contrast, the topography at the top of La Gomera is relatively gentle, making the transition seem even more exceptional, and more clearly climate-induced.  

Remnant patch of transitional forest, with semi-desert beginning at the right side (my photo)

Remnant patch of transitional forest, with semi-desert beginning at the right side (my photo)

Path of the 2012 fire

Path of the 2012 fire

This ecotone may be the most dramatic of any I've experienced anywhere.  But, as I mentioned earlier, it was disappointing in its own way.  In 2012, a fire beginning at the mouth of the Valle Gran Rey in the southwest swept across the island, just to the south of the central ridge, destroying nearly all the southern fringes of the cloud forest where it meets the arid southern slopes.  From what I could tell, only a tiny segment of the transition remains largely intact, and unfortunately it can't be accessed continuously along a single route.  But I was able to walk through a patch of low (about 2m high), very dense "forest" of large shrubs that seems to be a transitional environment between the two extremes:  the semi-arid landscape sloping away to the south just a few meters beyond, and the full-fledged cloud forest about a 10-minute walk in the other direction.   The low stature, gnarled trunks, tiny thick leaves, and prevalent mosses make the interior somewhat reminiscent of an elfin cloud forest atop a windy ridge.  The experience of standing in such a forest at the edge of a semi-desert was electrifying, perhaps even more so knowing that at present, it can be had nowhere else on the island (or perhaps in the entire archipelago).  

Charred transitional forest with Alto de Gajaronay in the distance (my photo)

Charred transitional forest with Alto de Gajaronay in the distance (my photo)

Of course, though, I would have preferred the experience to have been much more widespread and accessible, at the cost of its feeling only slightly less exceptional.  In walking the gentle slopes up to the island's highest point, it was disheartening to see for myself the mostly charred and leafless transitional forest lining the trail (save a layer of new growth on the ground surface) and falling away to the south into a layer of fog.  A display at the summit featuring an image of a clear, pre-fire view to the south, showing the tantalizing transition from green to brown within a short hike , didn't help matters.   But I do wonder now whether, on a clear day, the sight of the short trees - even if leafless - and green carpet of new growth fading into rock and scrub in the distance would have brought some measure of excitement or additional aggravation. 

Darren

Display showing pre-fire transition from green to brown (my photo)

Display showing pre-fire transition from green to brown (my photo)