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Gavin Conochie, Henry Ford, Harriet Gillett, PhiL Trathan
The expedition, funded in part by the British Ecological Society and by a number of other sources, successfully completed its objectives outlined in the proposal which were to undertake a base line survey of the forest to provide data for future comparisons, and to try and understand the causes of the death of the forest. Phil Trathan (British Antarctic Survey) Harriet Gillet (World Conservation Monitoring Centre) Gavin Conochie ( translator and tree climber) and myself, spent 4 weeks in the field under the auspices of Djibouti Nature (Houssein Rayaleh) and Houmed Ali (Bakouale) and returned in April.
A previous expedition had reported the recent loss of the cloud forest of Juniperus procera in about 400 hectares of highland (1700m) in the Goda Massif in Djibouti. This area contains some 70 % of the terrestrial biodiversity in Djibouti which is primarily an arid volcanic desert. The forest provides limited grazing and the springs feed a number of terraced gardens growing fruit and vegetables, but there are fewer than 3000 people living in the area. It is home to the very rare Djibouti Francolin, a partridge like bird, and the Bankouale palm, of which only 400 individuals remain.
A modified English Nature protocol for woodlands was used to collect data from thirty eight 100 square metre quadrats, including a number of physical features as well as plant data, together with soil samples, diameter and breast height for trees and shrubs, and tree core samples in the forest. As there is currently no weather station in the area and the Djiboutiville weather station does not reflect the climatic conditions in the forest, we undertook a number of interviews to establish perceived changes in climate and in forest cover, as it was thought that a recent drought may have affected the forest. However, we know that Juniper is a hardy and slow growing species. Several previous floods and droughts were reported and some floods have produced catastrophic changes in the Wadi system, removing considerable areas of cultivable soil, and, on one occasion, destroying a complete village and terrace system, though without loss of life.
The French Government had previously (2003) established an exclosure in the forest to demonstrate the effects of grazing, but it had not been maintained. This year however we found that it had been restored for 18 months, and two further exclosures built. The results were dramatic and the herb and shrub layers were well on the way to complete restoration. More significantly, juniper seedlings which were non-existant elsewhere, were frequent under living juniper trees.
Our conclusion, based on the analysis of the data so far, is that extensive and prolonged grazing has been the cause of the decline of the forest, removing seedlings and preventing recruitment of the Juniper, and the death occurs primarily amongst old trees, though, as the canopy has opened and drought prevailed over the last 8 years, younger trees are becoming susceptible to dry conditions. No sign of any particular disease was found, and though the port of Djiboutiville is large, we doubt that pollution has much effect, though the soil analysis should reveal any results.