Other peoples' holiday photographs are usually painful, and I have five hundred images from chiefly Ecuador which I need to name before posting for general availability. Volunteers welcome: there seem an inordinate number of Sobralias, one twice the size of my hand. I will patch together a web page somewhere in the next weeks or two, but as I came back with both memories and malaria I am a bit slow at the moment.
General comment on what I saw is as follows. Orchid biodiversity seems to peak at around 1500m, 3000' more or less wherever you are in the world. Plants occur in clusters, with wide gaps in which there seem no orchids at all, or a very repetitive flora. South American plants have formidable competitors in the Bromeliads which is not the case in Asia, and many niches therefore do not exist for orchids. Old trees have disproportionate numbers of orchids on them, and old emergents most of all. The absolutely ideal situation seems to be a 7m tree with a very open canopy and corky bark, situated on an 80 degree slope. Such trees may have 20-30 species growing on them. The Humboldt current turns away from land close to the Northern Peru border, meaning that the utterly dry Sechura desert gives way to the Cerros the Amotape, and then the Ecuadorian Andes. In 50 km one goes from loose dunes to dense mist forest. Climbing through scrub that gets a few centimetres a year - sometimes - one finds a surprising array of orchids. None were in flower so I guess at the their being Epidendrons and Oncidiums. (One such was in flower somewhat higher up, pictures as above.) Mist forest, which occurs in isolated patches where the clouds spill between valleys in the late afternoon, has a much denser flora and there are accretions of literally tonnes of gunk in the upper branches, with orchids spotted through this. Both the Peruvian and Ecuadorian lowlands have a limited flora, so far as I could see: many plants, but always the same ones. The higher humid jungle or selva alta is very different as between Northern Peru and Ecuador. The former - Tarapoto, Jaunjui, Tingo Maria - is densely wooded with small scrub trees, and has limited to local orchid cover until one rises 250-500m. The Ecuador strip that occupies the same altitude and geography - Puyo, Macas, Zamora - is quite different: larger trees, clearings, uniform dense cover with orchids from a (fairly) limited range of species. The 'eyebrow of the jungle', the ceja de selva which starts at about 700m and rises to 2500m is the absolute focus for orchids in both countries. I cannot judge relative species count, but I would suspect that because Peru is much more climatically varied (and far larger) its ceja de selva is more diverse. However, as mentioned above, I have never seen anything like the Ecuadorian Sobralias, each one of which seems different from its predecessor. Like Arundina in Asia, a hybrid swarm. Why two unrelated genera should wind up both looking like each other but also displaying the same genetic traits is not clear. One unusual day was spent in the hot and humid coastal mist forest, which occurs where sea fogs hit the shallow coastal ranges of Southern Ecuador. One goes from arid scrub to dense Sumatra-like coastal forest in a few hundred metres of climb. Despite a diverse and colourful Bromeliad population and the presence of many other epiphytes, the orchid population seemed limited to an Oncidium species - not in flower, but with twining 3-4 m inflorescences - which was restricted to the edges of this forest. It seems to me that orchids do not like dense forest, more or less everywhere that I have traveled in the humid tropics. No doubt the world expert on this region will now refute what I have said, but I can only report what I saw. ______________________________ Oliver Sparrow +44 (0)1628 823187 www.chforum.org _______________________________________________ the OrchidGuide Digest (OGD) orchids@orchidguide.com http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
